The Fuzz Face and the Rangemaster
How do you think its best to place them with all your other effects. I have some "ideas" but I am not sure about that.
1) Guitar -> Fuzz Face -> Other effects -> Rangemaster -> Tube amp
Because of Gus Law (Guitar is part of the effect in the FF circuit) and because of the Rangemaster high output signal pushing the amp (not the effects)
Is that a good way to think ??? .
2) Guitar -> A/B box -> Other effects -A/Bbox -> Tube amp
| |
Fuzz Face --> Rangemaster
3) Guitar-> A/B/C Box -> Other effects -> A/B/C box -> Tube amp
| |
----------Fuzz Face---------------
| |
-- --------Rangemaster-----------
- Is it safe to place an "standard-modern" effect after the rangemaster of it should really be at the end of the chain ?
- Is it useless to put the Rangemaster in front of the Fuzz Face :icon_rolleyes: ?
- Are there other impedances issues (and/or other issues) with the RM and the Fuzz Face (other than the front end FF issue) ?
- Do you have other ideas or preferences ?
Thanks
F.H.P.
I usually put the rangemaster in a separate loop from other fx. It doesn't play well with buffers before or after it. It probably works okay in front of a fuzz face and you could probably put them in the same loop. The RM essentially becomes the first stage of the amp, like any booster, so using time delay fx after it is useless IMO, unless you put them in the fx loop of your amp and you don't rely on power amp distortion.
I usually run my FF clone after the wah, before other distortions/boosters so I can pump up it's voulme and run my rangemaster last after mods and delays for extra needed volume boosts.
Seems to work out real well this way with minimal noise.
YMMV.
Didn't one of Joe Gagan's confections consist of a Rangemaster into a FF? Having said that, a RM generally ought to see amp the way Adrian Peterson sees end zone.
Quote from: DougH on January 08, 2009, 01:46:42 PM
I usually put the rangemaster in a separate loop from other fx. It doesn't play well with buffers before or after it. It probably works okay in front of a fuzz face and you could probably put them in the same loop. The RM essentially becomes the first stage of the amp, like any booster, so using time delay fx after it is useless IMO, unless you put them in the fx loop of your amp and you don't rely on power amp distortion.
That seems backwards to me Doug. Delays always sound bad in FRONT of an amp unless the amp has lots of headroom and is ultra clean. Therefore, to me, the delay will sound really bad in front of a RM because those delayed repeats will still be getting crushed by the RM just like the front of a gainy amp would. I always run my RM first in my chain and my delays last and that way the delays stay clean. This doesn't work with my Trainwrecks (not much sounds good in front of them really) but it works great with my old Bassmans and my white Showman which all have lots of headroom.
Andy
Quote from: Ben N on January 08, 2009, 09:32:55 PM
Didn't one of Joe Gagan's confections consist of a Rangemaster into a FF? Having said that, a RM generally ought to see amp the way Adrian Peterson sees end zone.
The Skyripper, Ben ?
http://www.diystompboxes.com/smfforum/index.php?topic=53669.0
http://www.aronnelson.com/gallery/main.php/v/cathexis/Veroboard+Layouts/Skyripper/Skyripper.jpg.html
Did not find his other ones: Nitroburner, BrontoBoost, Dinausor, etc...
I wonder what Joe is doing, hope he is fine...
I don't know anything about football. Yeah if it ought to see the pickup it would score at the wrong place...
It would perhaps do like an electromagnetic gun... Damn where are my polepieces... ???
-----Fuzz---Other FX--------
Guitar- -A/B/Y (with blend if possible)--- -------Delay-------------Front of Amplifier
------------Rangemaster-----
(or run the delay in the FX loop if you have one)
This setup will alow you:
1 to have consistent delay between both channels.
2 To get a decent sound with a finnicky rangemaster that doesnt get along with your newly built phaser...
3 to get your main tone from the fuzz/other FX and be able to blend in some nice top end with the rangemaster
Keep in mind "Jimi's law".....Do I want to distort my wah tone or wah my distorted tone? Each will result in two completely different sounds. And this goes for any effect.
j/k about jimis law hehe
Quote from: hairyandy on January 09, 2009, 12:41:34 AM
Quote from: DougH on January 08, 2009, 01:46:42 PM
I usually put the rangemaster in a separate loop from other fx. It doesn't play well with buffers before or after it. It probably works okay in front of a fuzz face and you could probably put them in the same loop. The RM essentially becomes the first stage of the amp, like any booster, so using time delay fx after it is useless IMO, unless you put them in the fx loop of your amp and you don't rely on power amp distortion.
That seems backwards to me Doug. Delays always sound bad in FRONT of an amp unless the amp has lots of headroom and is ultra clean. Therefore, to me, the delay will sound really bad in front of a RM because those delayed repeats will still be getting crushed by the RM just like the front of a gainy amp would. I always run my RM first in my chain and my delays last and that way the delays stay clean. This doesn't work with my Trainwrecks (not much sounds good in front of them really) but it works great with my old Bassmans and my white Showman which all have lots of headroom.
Andy
I'm not suggesting running the delay in front of the RM. I'm saying that delays don't really work in a signal path with a RM. In general, the best place for a delay is to mic the amp and then run
that through a delay. Barring that, run the amp clean and put the delay at the end of the pedal chain or if the amp is a preamp-distorter you can probably put it in the fx loop.
The way I use the RM is to create distortion by boosting an amp that breaks up easily, so the distortion is really coming from the amp. The RM really becomes
part of the amp. I think most people don't realize that, but it helps you work out your signal chain if you think of it that way. Inserting a delay between the RM and amp doesn't sound very good. Also, my delay has a buffered bypass and the RM doesn't work well with a low Z signal anywhere in the chain (before or after), in the way I use it. BTW, my ToneSource (brown source derivative) has the same problem.
Quote from: DougH on January 10, 2009, 09:17:09 AM
I'm not suggesting running the delay in front of the RM. I'm saying that delays don't really work in a signal path with a RM. In general, the best place for a delay is to mic the amp and then run that through a delay. Barring that, run the amp clean and put the delay at the end of the pedal chain or if the amp is a preamp-distorter you can probably put it in the fx loop.
The way I use the RM is to create distortion by boosting an amp that breaks up easily, so the distortion is really coming from the amp. The RM really becomes part of the amp. I think most people don't realize that, but it helps you work out your signal chain if you think of it that way. Inserting a delay between the RM and amp doesn't sound very good. Also, my delay has a buffered bypass and the RM doesn't work well with a low Z signal anywhere in the chain (before or after), in the way I use it. BTW, my ToneSource (brown source derivative) has the same problem.
Gotcha. Another way I've gotten around this issue with my Trainwreck Express and Liverpool, which have no headroom whatsoever and break up pretty much immediately, is to use my DIY Airbrake attenuator. I added a line out to it and I run that signal back through the time-based stuff (delays and reverb) and then into a power amp and cab or something pretty clean like my Blonde Showman. That way you have a wet/dry thing with two cabs and you can put the boost stuff early in the chain in front of the TW.
Andy
If I remember correctly, the Keeley Fuzzhead is a variation of a RM feeding into a Fuzz Face type of circuit with a buffer that end. And I've heard one in the local music shop, it sounds pretty sweet to me.
Quote from: hairyandy on January 10, 2009, 10:49:06 AM
Gotcha. Another way I've gotten around this issue with my Trainwreck Express and Liverpool, which have no headroom whatsoever and break up pretty much immediately, is to use my DIY Airbrake attenuator. I added a line out to it and I run that signal back through the time-based stuff (delays and reverb) and then into a power amp and cab or something pretty clean like my Blonde Showman. That way you have a wet/dry thing with two cabs and you can put the boost stuff early in the chain in front of the TW.
Andy
Yeah, that's a good idea. I was working on something where I ran the mic signal through delays and etc and then give that to the soundman for the p.a, but it was tricky getting all the levels right. I like your wet/dry idea better, just using two amps. :icon_cool:
Gonna try this with my Hot-Plate this week. Good idea !
I think it's time to add that line out to my attenuator that I have been meaning to do. :icon_wink:
my girlfriend runs:
wurlitzer 200a > RM > fuzz face > DL4 > pt80 > holy grail > ampeg gemini 1x15
sounds great... the rangemaster has an input attenuator and a tone control (to get a little more lows) to get the wurlitzer to play well.
:icon_eek:
The attenuator method works great. Sounds REALLY good with the Rangemaster. The best sound I got was with my Traynor 15 in. bass ported cab at the output. Like this :
Guitar ->Rangemaster-> Fender Princeton -> Hot Plate line out -> PA with graphic EQ (with delay and other effects in the effect loop) -> Traynor 15 in. ported cab.
Didn't try with the wah yet
Wonderful ! When I crank the Princeton, I cut the bass on the tube amp and give back the bass with the PA. With smaller speaker or open cab, it sounded a bit fizzy. But now it's crunchy, creamy and punchy !
I am surely going to use this method now (at least for practice at home it's perfect).
I still have problems with the Fuzz Face. Perhaps I should put some lower gain trannies in my DIY Fuzz Face...
I added the line-out to my attenuator and agree- the wet/dry method sounds great! :icon_wink:
I never even got to the Rangemaster, but I'm certain it will sound good. I was using my 2W Dragonfly amp which gets plenty of distortion on its own- and cleans up with a twist of the guitar volume control. So I ran that into the attenuator, then a line to the 1x12 cab. Then the line-out went through my chorus/delay/roto-machine pedals into my SS amp. The SS amp had the para EQ tuned for a 100hz peak which adds a nice kick to the open back 1x12. It sounded really great and the difference between the two speakers is very cool. Enjoyed the stereoization of the fx too. With the attenuator and line-out volume control it was real easy to control levels of everything. I'll try it again with a tamer amp and the Rangemaster (and other boosters).
Thanks to Andy for suggesting this. :icon_cool: I've heard of this before but never really knew how people set it up.
Quote from: DougH on January 11, 2009, 07:59:08 PM
Thanks to Andy for suggesting this. :icon_cool: I've heard of this before but never really knew how people set it up.
Nice. Glad yer all having fun! Lots of guys used variations of this idea with different amps in rack setups in the 80's. The line out was a common amp mod and some amps even came with a line out from the factory. God, could you imagine still lugging around a 16-space rack with a Crown DC-300 in the bottom of it?
Andy
Long ago I did something like that with my late-70s Deluxe Reverb, which came with a line out, and a similar sized hybrid amp with an fx loop right between the SS preamp and the tube phase inverter. I ran the line out, somewhat padded down, through chorus & delay, including an Alesis Nanoverb, into the other amp's fx return. Sounded great. With a so-called "stereo" chorus (the kind that splits wet and dry into separate outputs), I just ran the wet signal into the slave.
Quote from: hairyandy on January 11, 2009, 09:36:24 PM
Quote from: DougH on January 11, 2009, 07:59:08 PM
Thanks to Andy for suggesting this. :icon_cool: I've heard of this before but never really knew how people set it up.
Nice. Glad yer all having fun!
Andy
Yes forgot to say: thanks Andy.
Playing with the EQ of the second amp and trying different cabs does make a good difference on how good it will sound.
Quote from: hairyandy on January 11, 2009, 09:36:24 PM
Lots of guys used variations of this idea with different amps in rack setups in the 80's. The line out was a common amp mod and some amps even came with a line out from the factory. God, could you imagine still lugging around a 16-space rack with a Crown DC-300 in the bottom of it?
NIGHTMARE ! But that's why I said -for home practice- . Can not imagine carrying my tube amp, the PA system and the 15 in. speaker cab. for each practice neither...
But if you practice in a studio where they have a "sound system" you could bring a low power tube amp head (something light) and your effects and attenuator without a big backache !
The next thing I want to try is just using the amp as a "distortion pedal". Just use the attenuator as a load box and run the line-out through the fx, then tap off the stereo buss there to two different clean amps. The stereo processing of the tonecores is pretty good and it would be fun to put the "stereoization" in their hands instead of going wet/dry.
This would be a ridiculous amount of equipment to carry around. :icon_wink:
I thought of an idea I may work on later this year- Get a couple chip amp kits from qkits.com and build up a stereo SS power amp. Then build up a stereo speaker cabinet- one cabinet with a speaker per side with a corner between them (90 deg apart). Someone mentioned doing this last year and IIRC it dispersed the stereo sound real well. For low volume and/or ease of transporting this could be a ported cab with a couple 8" speakers. Then run the tube amp (or amp and booster, RM, whatever "pre" amp pedals you want, etc) with the attenuator as the dummy load & run the line-out through the stereo fx and out to the stereo SS amp/cab. Then come up with some kind of box, rack, whatever to put the tube amp, SS amp, and attenuator in for easy setup...
That's a good idea...
But for me, if I enter an other cab. or combo in the house, I am gonna get killed. :P
I can only use what is already there. :icon_mrgreen:
Unless I sell or... hmmm... convert something.
I have two 8in. alnico speaker with closed back aluminium army cabs.
One speaker is broken. I'll have to find something similar to the other one.
Doug do you think that a guitar could sound good in a stereo 8in. speaker with this attenuator setup ? ;D
I might need some kind of bass booster in the SS amps (?)
Well, I'm getting ready to build a simple ported 8" cabinet to see how it sounds. I experimented with the speaker in its original cab closed back and then open back with a cardboard box behind to get different sounds and I think I can get a decent low-volume sound out of it. So after that I'll think about the stereo idea some more.
Cool !
:)
Just to follow this up- I tried the "wet-wet" setup (using the attenuator as a load only and running the line out through the stereo fx buss to two amps) last night. It sounded real nice too. For stereo fx like the Tonecores, that do more than just divide the signal into wet/dry outputs, this works real well and allows the fx to do the "stereo imaging".
If I had a third speaker cab I would connect it to the attenuator and try "wet-dry-wet" too. :icon_wink:
All these techniques are pretty hardware-intensive. I think it would be a nightmare to drag all this stuff around have to set it up and break it down. But for home/studio it works well and sure sounds great. And a side benefit is you really have control of your volume level. You can really get a "big" stereo sound at a reasonable volume level for "at home" playing.
For me that drove (is that the right word) me to question myself about what's going on before and after the attenuator (and by extension, in the amp, but I don't have a scope for high voltage...). I think I will do some scoping this week and compare the wave shapes before and after the attenuator, and that for different amps. Playing in different output cabs (and SS amps) made me realise how raspy and fizzy some of my tube amps are sounding when listened at low volume with the attenuator. I suspect that many of my tube amps have more of a rather "hard clipping" behavior than I think. So I wonder if it's coming out of the amp or it is due to the attenuator. It might also be the way that the ear (or brain) perceive distortion at different volumes. Anyway, the question is that I am now in doubt in my belief that tube amps always have a softer clipping than the SS apparatus. Perhaps what is going out of some of my amps is more clipped or "squared" than I would have guessed at a first tought. So by cutting some hights on the output SS amp, I am just, perhaps putting together the same idea that what is in the tubescreamer (?).
The THD hot plate is not a purely resistive device as opposed to the Z airbrake. I opened it a wile back and there are some inductances in there, I don't know if it's for filering or impedance matching or simulation of the voice coil. I also remember that the Z Airbrake got better reviews than the Hot-Plate. So I wonder if the complexity of it's circuit really bringed something to it in comparison with other attenuators that are less complex.
Now I am in front of so many variables that can affect why the distorted tone do sound a bit raspy at lower volume. I really wonder if the wave shapes are similar out of the tube amp and out of the attenuator. If so, my religious belief that tube amps all have smooth clipping in the power amp will come to an end.
Now, if the waves are really more clipped what would it be due to (?) : "bad" design of the power amp in relation to the power supply or the output transformer ? Perhaps some of my amps are not well biased ? I don't know for the moment. But it's a moment of doubt.
If I wanted to do a frequency and amplitude sweep on my attenuator, in the goal of scoping what's going on out of there, would I have to drive it ? If so, what would be a good method ? A SS amp, a power opamp or a power transistor ?
I think I could go in endless experimentation with that stuff...
There are too much things I don't understand for now.
The gain of the Fuzz Face is roughly the 100k feedback resistor divided by the input impedence of the source signal (your guitar or the preceeding effect).
Because the feedback resistor 'starts' at the emitter of Q2, it is analogous to placing it from the collector to base of Q1, the only difference being the Vbe drop of Q2.
It may be an interesting experiment to install a DPDT switch that allows one to switch in/out a 50k log or 20k-25K linear pot, that way if you are going direct from the guitar you can bypass the pot, but if you are connecting it after an effect with a buffered output you can switch the pot in series with the FF input and manipulate the gain by raising the signal's input impedence to the base of Q1.
Regards,
Jay Doyle
Frank, from my experience a lot of it comes down to how the ear-brain perceives freq response at lower volume (less bass). More bass in the sound tends to warm it up and mask some of the highs, in my perception of it.
I did a comparison once with an attenuator using my mass motor vs. a purely resistive load. The mass load had more high-freq response, kind of like a speaker. The resistive load sounded rolled-off and more "middy". Maybe people like the high freq rolloff when they turn it down and lose the perception of bass too in the Airbrake- maybe that "equalizes" it in their mind. Some of the trainwreck amp clips sound kind of spikey and raspy to me. Maybe the rolloff of the purely resistive load in the attenuator helps that, I don't know. That's just speculation on my part.
I agree that EQ-ing for less treble on the "slave" amps in the wet-dry or wet-wet configurations sound better. But then, you don't need "more EQ-ing" since you are already doing that with the amp that is being attenuated. Otherwise you are exaggerating the EQ (2 EQ's in series). I'm guessing that's why so many just use SS power amps as "slaves" in these kinds of setups- flat EQ and just there to drive the speakers. I'm speculating that may be a better solution than using a guitar amp. But guitar amps seem to work too, as long as they have enough headroom and you set the EQ fairly flat. I did "flatten" the EQ of my SS amp before I quit last night and noticed the sound vastly improved and smoothed out. I'm going to experiment with this some more.
Quote from: DougH on January 14, 2009, 04:17:53 PM
Frank, from my experience a lot of it comes down to how the ear-brain perceives freq response at lower volume (less bass). More bass in the sound tends to warm it up and mask some of the highs, in my perception of it.
I did a comparison once with an attenuator using my mass motor vs. a purely resistive load. The mass load had more high-freq response, kind of like a speaker. The resistive load sounded rolled-off and more "middy". Maybe people like the high freq rolloff when they turn it down and lose the perception of bass too in the Airbrake- maybe that "equalizes" it in their mind. Some of the trainwreck amp clips sound kind of spikey and raspy to me. Maybe the rolloff of the purely resistive load in the attenuator helps that, I don't know. That's just speculation on my part.
Ok Thanks for your input.
Quote from: DougH on January 14, 2009, 04:17:53 PM
I agree that EQ-ing for less treble on the "slave" amps in the wet-dry or wet-wet configurations sound better. But then, you don't need "more EQ-ing" since you are already doing that with the amp that is being attenuated. Otherwise you are exaggerating the EQ (2 EQ's in series). I'm guessing that's why so many just use SS power amps as "slaves" in these kinds of setups- flat EQ and just there to drive the speakers. I'm speculating that may be a better solution than using a guitar amp. But guitar amps seem to work too, as long as they have enough headroom and you set the EQ fairly flat. I did "flatten" the EQ of my SS amp before I quit last night and noticed the sound vastly improved and smoothed out. I'm going to experiment with this some more.
The slave amps I used this week were mono mixing-PA amps and my keyboard amp with different sort of cabs. I don't have any SS guitar amps and never had one (except fof my Rolland mini cube).
The first SS combo I bought was a Keyboard amp (Peavey KB 60) because at the time I was playing a diatonic nylon strung Paraguayan harp (36 strings). So the salesman at the music store sold me that: it was perhaps a better idea to mike the harp in a keyboard amp.
Anyway, I never succeded to amplify the harp convinently. The damn harp is a feedback monster; with 36 strings and a spurce top that is so thin that you can see the sunlight when looking in the sound holes, it's really difficult to play in an electric band with it. I have a plan to build an electric harp "in the future".
The PA-mixer with graphic EQ in it is great for experimentation with the attenuator.
Thanks Doug for all your time explaining me some stuff.
Quote from: JDoyle on January 14, 2009, 02:47:50 PM
The gain of the Fuzz Face is roughly the 100k feedback resistor divided by the input impedence of the source signal (your guitar or the preceeding effect).
Because the feedback resistor 'starts' at the emitter of Q2, it is analogous to placing it from the collector to base of Q1, the only difference being the Vbe drop of Q2.
It may be an interesting experiment to install a DPDT switch that allows one to switch in/out a 50k log or 20k-25K linear pot, that way if you are going direct from the guitar you can bypass the pot, but if you are connecting it after an effect with a buffered output you can switch the pot in series with the FF input and manipulate the gain by raising the signal's input impedence to the base of Q1.
Regards,
Jay Doyle
And for the Fuzz Face, it's opened on the operation table. Thanks also Jay. :)
My experiments continues...
QuoteThanks Doug for all your time explaining me some stuff.
Hey, no problem Frank. A lot of it is just speculation so take my advice for what it's worth (i.e. what you paid for it :icon_wink:).
Just to clarify one point- I don't think there's anything special about SS vs tube on the slave side, and I believe the "flat EQ" is probably a good idea either way.
Quote from: DougH on January 15, 2009, 10:44:29 AM
Just to clarify one point- I don't think there's anything special about SS vs tube on the slave side, and I believe the "flat EQ" is probably a good idea either way.
Two qualifiers:
1) There is nothing special about tubes
assuming you are running pretty much in the linear region, either because your SS slave has plenty of headroom (like 100 watt hifi amps that are functionaly equivalent to 2x6L6, because God forbid the SS power amp ever hit saturation), or because the dynamic range of the signal going in is limited. I think it is a good idea to include some kind of limiter (perhaps switchable) at the input of the slave--maybe something like the old Vox SS amps? Personally, I think limiting (that tube amps do organically) is actually preferable to high headroom, since a lot of dynamic range is not necessarily a good thing in a performance (as opposed to a listening) situation.
2) Flat EQ--again, assuming either of two situations: (a) that your slave is driving a cab that rolls off frequencies pretty much the same as the master amp does or would (a la EVH's 80s setup, with the power amps driving 4x12s), or (b) if your cab is full-frequency, like a PA cab, that your line out has some filtering to roughly simulate a speaker cab. When I used the line out on my old Deluxe reverb, it was unusable into a PA, but worked ok into the fx return of a guitar amp. I guess the most versatile solution would be a full range cab with a switchable cab sim built into the amp.
Quote from: Ben N on January 15, 2009, 11:29:43 AM
...I think limiting (that tube amps do organically)...
Just to be nitpicky - all amps 'limit' as you are using it, it's just that tube amps do so in a much more pleasing manner than solid state. Plus, especially in the realm of hifi, the amount of negative feedback is the determining factor in the abruptness of the onset of the 'limiting'. Because the transfer curve of a tube is much more linear than either FETs or BJTs, less negative feedback is needed to correct the distortions created in the amplifying process. BUT there are other advantages to negative feedback, especially in the case of hifi, such as desensitizing the gain across the frequency spectrum, increasing the bandwidth and altering the input and output impedences up or down (which is what makes 'emitter/source degeneration' similar to, but in the end, different from, negative feedback; not that anyone cares).
And as an aside, placing a limiter of some sort in an amplifier restricts the available output power. Baxandall has a good article about this in Wireless World from 1980, I think...
Jay Doyle
Quote from: JDoyle on January 15, 2009, 11:58:17 AM
Quote from: Ben N on January 15, 2009, 11:29:43 AM
...I think limiting (that tube amps do organically)...
Just to be nitpicky - all amps 'limit' as you are using it, it's just that tube amps do so in a much more pleasing manner than solid state.
OK, Jay, you know that's what I meant, but you did put it more precisely. :)
QuoteAnd as an aside, placing a limiter of some sort in an amplifier restricts the available output power. Baxandall has a good article about this in Wireless World from 1980, I think...
Even if the limiter really just precedes the amp?
Apropos of this discussion, http://www.diystompboxes.com/smfforum/index.php?topic=73342.0;topicseen (http://www.diystompboxes.com/smfforum/index.php?topic=73342.0;topicseen)--the "passive speaker sims" discussed are passive filters used to tone down the line outs of various amps so they are usable. This simplest, of course, is just a RC.
For my purposes I'm not interested in purposely getting distortion in the slave units. I'm using guitar speakers so I'm not interested in the slaves doing EQ-ing either. I'm mainly looking for a lot of headroom and enough power to play "loud enough" while the power slaves stay clean. Basically I just want to amplify a facsimile of the loaded tube amp at the beginning of the chain (with/without additional fx processing), then let it get EQ-ed by the guitar speakers. So for me, I don't really care what the form of the slaves are as long as they meet those requirements. (In this instance I don't think limiting is necessary for SS.) I think an SS power unit is probably the easiest way of doing it esp if you want to make it a compact unit for transport. Other than that I don't think it makes much difference to me.
Quote from: Ben N on January 15, 2009, 11:29:43 AM
2) Flat EQ--again, assuming either of two situations: (a) that your slave is driving a cab that rolls off frequencies pretty much the same as the master amp does or would (a la EVH's 80s setup, with the power amps driving 4x12s), or (b) if your cab is full-frequency, like a PA cab, that your line out has some filtering to roughly simulate a speaker cab. When I used the line out on my old Deluxe reverb, it was unusable into a PA, but worked ok into the fx return of a guitar amp. I guess the most versatile solution would be a full range cab with a switchable cab sim built into the amp.
I think that is why it sound good in the bass cab on my side.
Quote from: JDoyle on January 15, 2009, 11:58:17 AM
BUT there are other advantages to negative feedback, especially in the case of hifi, such as desensitizing the gain across the frequency spectrum, increasing the bandwidth and altering the input and output impedences up or down (which is what makes 'emitter/source degeneration' similar to, but in the end, different from, negative feedback; not that anyone cares).
Ouch Jay... Do you have some reading to suggest me. With graphs and equations. There is a lot of stock in that phrase...
Quote from: DougH on January 15, 2009, 01:06:54 PM
For my purposes I'm not interested in purposely getting distortion in the slave units. I'm using guitar speakers so I'm not interested in the slaves doing EQ-ing either. I'm mainly looking for a lot of headroom and enough power to play "loud enough" while the power slaves stay clean. Basically I just want to amplify a facsimile of the loaded tube amp at the beginning of the chain (with/without additional fx processing), then let it get EQ-ed by the guitar speakers. So for me, I don't really care what the form of the slaves are as long as they meet those requirements. (In this instance I don't think limiting is necessary for SS.) I think an SS power unit is probably the easiest way of doing it esp if you want to make it a compact unit for transport. Other than that I don't think it makes much difference to me.
I think I didn't explain myself clearly. I just said I don't have any SS GUITAR amps. I used SS pa-mixer amp and SS keyboard amp (No SS guitar amp as slave).
I need to cut high in any case. Tube guitar amps do it by themselves it seeems, not the keaboard amp (thats why the keyboard combo don't sound good). I think that when everything is set "flat" on a SS guitar amp, it's not a flat response that you finally have (well, less than a keyboard amp). That's perhaps why it sound better with a guitar amp: there is already some treble cut.
The best result I had was with the SS PA-mxer amp and bass cab (to cut high requencies at low volume).
QuoteI think I didn't explain myself clearly. I just said I don't have any SS GUITAR amps. I used SS pa-mixer amp and SS keyboard amp (No SS guitar amp as slave).
I need to cut high in any case. Tube guitar amps do it by themselves it seeems, not the keaboard amp (thats why the keyboard combo don't sound good). I think that when everything is set "flat" on a SS guitar amp, it's not a flat response that you finally have (well, less than a keyboard amp). That's perhaps why it sound better with a guitar amp: there is already some treble cut.
Frank, I think my comments were directed more at Ben and maybe Jay. I think the reason your pa and keyboard rigs need highs cut is probably due to the speakers. That's why for me I like to use guitar speakers as they already provide the rolloff.
Exactly. OK sorry, Doug.
For the Fuzz Face:
Quote from: JDoyle on January 14, 2009, 02:47:50 PM
It may be an interesting experiment to install a DPDT switch that allows one to switch in/out a 50k log or 20k-25K linear pot, that way if you are going direct from the guitar you can bypass the pot, but if you are connecting it after an effect with a buffered output you can switch the pot in series with the FF input and manipulate the gain by raising the signal's input impedence to the base of Q1.
Jay Doyle
Just like late 60's Fuzz and with a switch, OK. I don't know why I didn't remembed that. RG explained it already in the technology of the fuzz face. (the Fulltone 69 mod).
Making the front end like a current source instead of a voltage source. This is perhaps a good project for measuring and doing some maths.
Like this (late 60's on GGG):
http://www.generalguitargadgets.com/pdf/ggg_ff5_sc_b69.pdf
I think I'll just build a new one.
Quote from: frank_p on January 15, 2009, 02:39:40 PMJust like late 60's Fuzz and with a switch, OK. I don't know why I didn't remembed that. RG explained it already in the technology of the fuzz face. (the Fulltone 69 mod).
Gotta admit I didn't remember R.G. talking about it in the Tech of... article, or that fuller had done it either. It honestly has been quite a while since I've looked at commercial schematics or read that article. I just know that the fuzz face topology is an old circuit, a really old circuit. Ghausi (I think I'm spelling it right) wrote a few articles delving into it back in the 60s; it was considered to be a 'wideband' amplifier (if you think about it, because the signal at the emitter of Q2 is almost exactly the same as the signal at the collector of Q1, the parasitic Miller capacitance of Q1 has the same signal appear at both ends of it, and therefore its effect is reduced considerably, extending the bandwidth). The only thing missing in the Fuzz Face schematic is an input series resistor, and that can be replaced with either the impedence from the preceding effect or that of your guitar.
Multi-transistor feedback threory can get dizzyingly heavy on the math (I'm an ignorant American, math is singular to me ;) ) but one of the better articles, if you are up for it, is here:
http://users.ece.gatech.edu/~mleach/ece3050/notes/feedback/fdbkamps.pdf
As for the other comment about you wanting me to post some stuff about my negative feedback comments earlier, I don't have anything I can find online about neg. fdbk vs. emitter degeneration. My statement stems from the definition of feedback, in that it does those things I've mentioned, where as emitter/source degeneration only reduces the gain and just because something exhibits one aspect of something else does not mean that it IS that something else. Even The Art of Electronics states that emitter degeneration is a 'form' of negative feedback (but then admittedly gets a bit foggy later on). Further, the basic definition of negative feedback requires a portion of the output signal to be sent to the input, and while the action within a transistor EFFECTS what happens at the input, the OUTPUT of the transistor, the portion that has 'gain', is NOT sent back to the input by adding a emitter/source resistor. Therefore, inserting an emitter/source resistor may reduce the gain, but any reduction in distortion is secondary to that effect; and all of the other postitive aspects of negative feedback are essentially missing. But don't worry, it's probably all semantics anyway. :D
ANYWAY:
As for articles on distortion in power amplifiers, the following really deal with solid state
HIFI amps, and amplifiers utilizing negative feedback, but are the best available online by far and should keep you or anyone busy for quite some time.
(Plus, lots of graphs, math, and experiments! :) )
Here is a great series of articles by Baxandall:
http://www.linearaudio.nl/Documents/Baxandall%20power%20amp%20design.pdf
And a long series from Douglas Self adapted from his book "Self on Audio":
http://www.audiodesignline.com/showArticle.jhtml;jsessionid=QJI2ZCP0FRZ5KQSNDLPCKH0CJUNN2JVN?articleID=205207238&queryText=distortion+in+power+amplifiers
http://www.audiodesignline.com/showArticle.jhtml;jsessionid=QJI2ZCP0FRZ5KQSNDLPCKH0CJUNN2JVN?articleID=205601405&queryText=distortion+in+power+amplifiers
http://www.audiodesignline.com/showArticle.jhtml;jsessionid=QJI2ZCP0FRZ5KQSNDLPCKH0CJUNN2JVN?articleID=205801115&queryText=distortion+in+power+amplifiers
http://www.audiodesignline.com/showArticle.jhtml;jsessionid=QJI2ZCP0FRZ5KQSNDLPCKH0CJUNN2JVN?articleID=205917273&queryText=distortion+in+power+amplifiers
http://www.audiodesignline.com/showArticle.jhtml;jsessionid=QJI2ZCP0FRZ5KQSNDLPCKH0CJUNN2JVN?articleID=206100517&queryText=distortion+in+power+amplifiers
http://www.audiodesignline.com/showArticle.jhtml;jsessionid=QJI2ZCP0FRZ5KQSNDLPCKH0CJUNN2JVN?articleID=206105223&queryText=distortion+in+power+amplifiers
http://www.audiodesignline.com/showArticle.jhtml;jsessionid=QJI2ZCP0FRZ5KQSNDLPCKH0CJUNN2JVN?articleID=206503400&queryText=distortion+in+power+amplifiers
http://www.audiodesignline.com/showArticle.jhtml;jsessionid=QJI2ZCP0FRZ5KQSNDLPCKH0CJUNN2JVN?articleID=206800813&queryText=distortion+in+power+amplifiers
And here is one that (first) hit on the fact touched in each of the above, that while negative feedback is overall a good thing, if you are going to use it, a little bit is worse than a lot:
http://www.linearaudio.nl/Documents/feedback%20fallacy%20scroggie.pdf
Enjoy!
Jay Doyle
P.S. - Ben N.: you are right, if the limiting is at the beginning, it will only effect the dynamic range of the input signal, not the output ability of the amplifier itself. I apologize, I read your post incorrectly. - JD
Another thing worth mentioning, Jay, is when you mention negative feedback I think you are referring to global negative feedback. :icon_wink:
Yours in nitpickery,
Doug
:icon_wink:
OK, guys... I can't reply... For now...
I am reading Mr. Doyle's documentation.
And I am overwhelmed.
And I am REALLY happy with it. There will be no negative feedback from my side.
Didn't find find Ghausi's articles on wideband amps on the net, but hey, I have already a lot of stuff to read.
Plus found more things on feedback in Ch. 8 of my Sedra Smith's book.
And:
http://en.wikipedia.org/wiki/Asymptotic_gain_model#Two-stage_transistor_amplifier
http://en.wikipedia.org/wiki/Negative_feedback_amplifier#Two-port_analysis_of_feedback
Sedra
Ch 8.2:
- Gain Desensitivity (desensivity factor)
- Banwith extension
- etc.
Multi-transistor feedback threory can get dizzyingly heavy on the math (I'm an ignorant American, math is singular to me Wink ) but one of the better articles, if you are up for it, is here:
http://users.ece.gatech.edu/~mleach/ece3050/notes/feedback/fdbkamps.pdf
I have some bases in maths, but I am rusted... And I know that even with knowledge of maths, those circuits can be very hard to analyse.
If you're an ignorant, you'll be happy to know that I live in an igloo and I eat beavers up in Canada.
Great ! There are even examples at the end of the paper. Plus: the link at the top:
http://users.ece.gatech.edu/~mleach/ece3050/notes/feedback/FBExamples.pdf
And more (to read till I die) at the same site:
http://users.ece.gatech.edu/~mleach/ece3050/
As for the other comment about you wanting me to post some stuff about my negative feedback comments earlier, I don't have anything I can find on-line about neg. fdbk vs. emitter degeneration.
I found nothing either in french on that subject. I don't even know if I can translate it by "dégénerescence d'émetteur" or it's an other term or expression in french. All google is giving me is psychology papers...
Even The Art of Electronics states that emitter degeneration is a 'form' of negative feedback (but then admittedly gets a bit foggy later on). Further, the basic definition of negative feedback requires a portion of the output signal to be sent to the input, and while the action within a transistor EFFECTS what happens at the input, the OUTPUT of the transistor, the portion that has 'gain', is NOT sent back to the input by adding a emitter/source resistor. Therefore, inserting an emitter/source resistor may reduce the gain, but any reduction in distortion is secondary to that effect; and all of the other postitive aspects of negative feedback are essentially missing.
I have the book, I have to search (more) in it...
But don't worry, it's probably all semantics anyway.
Yes, electrons are negative also.
I'll continue tomorrow, it's getting late, and it's been four hours I've been on you post Jay. :D
It's really OVERLY GENEROUS : these papers are REALLY great ! I do not understand everything, but enough to understand their values.
I'll continue to read the papers on feedback in power amps tomorrow (and in the next weeks).
All this will be usefull.
Big thanks.
Hugo-Franc. P.
P.S.: Yes, Vbe is not VBE... But can I write V_be ? ;D
Quote from: DougH on January 15, 2009, 09:34:31 PM
Another thing worth mentioning, Jay, is when you mention negative feedback I think you are referring to global negative feedback. :icon_wink:
Yours in nitpickery,
Doug
:icon_wink:
;D
BUT - when I mention 'negative feedback' it could refer to
either global (output to input of an entire amplifier with anything in between, as long as there is gain) or local (collector to base, drain to gate) - in either case a portion of the output is sampled and 'sent back' to the input, whereas with emitter/source degeneration, one is altering the input node's 'sensitivity' to signals presented to it.
I admit that it is mostly nitpickery - but I think it is an important distinction none the less. For example, you can have an emitter degenerated stage and still use negative feedback from the collector to the base, or to use a more concrete example, do something like one of the stages in the Big Muff with diodes facilitating the negative feedback, yet the stages are still emitter degenerated. If placing a resistor from the emitter to ground is negative feedback, how would one replace the resistor with diodes to achieve the same/similar result as in the stages of a Big Muff? If you placed them anti-parallel with the emitter resistor and fed them with a cap, you would get the opposite effect as in the Big Muff: once the Vth of the diodes was crossed, the gain would
increase as they would then present a lower resistance than the emitter resistor.
Still, it IS nitpicky. ;)
Jay Doyle
Hey Jay, I wasn't accusing you of being nitpicky, I was just making a joke because I thought my response sound nitpicky. :icon_wink:
Anyway, I completely agree- degenerative feedback is different and has different effects than both global or local negative feedback.
One often makes a remark and only later sees how true it is. - Ludwig Wittgenstein
Quote from: DougH on January 16, 2009, 12:13:32 PM
Hey Jay, I wasn't accusing you of being nitpicky, I was just making a joke because I thought my response sound nitpicky. :icon_wink:
Anyway, I completely agree- degenerative feedback is different and has different effects than both global or local negative feedback.
No harm, no foul at all Doug - I was laughing even though I misunderstood!
Oh, one last thing for Frank - skip the Ghausi papers altogether, in my opinion. Brutal, mind numbing math. Though at one point he does say something to the effect of 'I'm not going to solve the equations any further because it gets too complex and the result is fairly useless.' I remember laughing at that...and then thinking 'Damn, I need to get out more...'
Have a great weekend all!
Jay Doyle
Quote from: JDoyle on January 15, 2009, 05:49:25 PM
(...) just because something exhibits one aspect of something else does not mean that it IS that something else. (...)
When in doubt, don't forget to read this Jay:
http://web.archive.org/web/20051210213153/http://budni.by.ru/oncertainty.html
Have a good weekend too.
HFP
QuoteThough at one point he does say something to the effect of 'I'm not going to solve the equations any further because it gets too complex and the result is fairly useless.'
If you ever want a mind-numbing good time, try plotting a Bode plot for a pedal circuit doing the calculations manually. There's a reason we use computer sims! :icon_wink:
I've not touched bode plots, poles and zeros, and all that stuff since about seven years. Two weeks ago, I've found my copies of class notes from my maths classes and control-modelisation for mechatronics... Ouf... I've forgotten a lot of that stuff. And what we had studied was not for "real electronic circuits". It was for control: PIDs, stability, etc... All my teachers worked in the vibro-acoustic research group so they were very enthusiasts of that kind of stuff. So, since I liked sound theory, I took one master class (postgraduate) in vibro-acoustic. I recall, it was tough theory (and I don't remember of most of what I've done there). At that time in the lab they were conducting researches in vibration control in airplane structures, so there was a big model of a fuselage and one of it's wing (aluminium) of a commercial airplane, and all that structure was connected with tons of accelerometers and solenoids-actuators (I don't remember the real name) to develop a system that would control noise and vibration in real time by injecting impulsions in the real aluminium model. It was impressing. But, in fact the last time I touched that stuff was when I returned in school and it was for models of rheological and visco-elastic behavior of polymers. Since molten plastics behavior models are often constituted of ensembles of masses, elastic elements (springs) and viscous elements (dampeners), the models are similar to filters.
A bit similar to that stuff:
http://www.it.uu.se/research/publications/lic/2005-005/2005-005.pdf
But for circuits with active components other than ideal opams and RCL, I really don't know what to do. And still, I've lost the hand for that kind of things. I would have to revise and study (a lot). Perhaps one day, you guys will give me help for the electrical side.
So I understand, when you guys say that it is complex. Even in my field I find it complex (and I am not a math addict). :icon_neutral:
P.S.: And for bode plots I used Matlab, not my hand, neither electronic softwares.
:D
See you soon !
Oh ! I have a HP gain-phase meter (3575A), it should help in that kind of stuff.
(http://www.amplifier.cd/Test_Equipment/Hewlett_Packard/HP_meter/images/3575A.jpg)
http://www.amplifier.cd/Test_Equipment/Hewlett_Packard/HP_meter/HP3575A.htm
Quote from: hairyandy on January 09, 2009, 12:41:34 AMDelays always sound bad in FRONT of an amp unless the amp has lots of headroom and is ultra clean
I'd say that U2's The Edge it's a brilliant example that what you say it's not completely true: he always uses delays in front of Vox AC30s pushed in overdrive.. :)
Brian May, too. Maybe AC30s are the exception!
Quote from: nooneknows on January 17, 2009, 04:32:52 PM
Quote from: hairyandy on January 09, 2009, 12:41:34 AMDelays always sound bad in FRONT of an amp unless the amp has lots of headroom and is ultra clean
I'd say that U2's The Edge it's a brilliant example that what you say it's not completely true: he always uses delays in front of Vox AC30s pushed in overdrive.. :)
Well yes and no. You are partially correct, maybe I shouldn't have said "always". Edge has done that in the past, mostly in the studio where it's easier to control just how hard he hits the amp with the delay. He uses the old Korg SDD-3000 delays and the TC2290s for most of his delay sounds. Since U2 has moved into bigger arenas at the end of the 80's he's relied less on the front end of the amp being crushed to achieve his distorted sound. Here's a great explanation of his recent rig by his tech Dallas where he somewhat touches on this subject:
http://www.youtube.com/watch?v=RGHqoUOT_z4 (http://www.youtube.com/watch?v=RGHqoUOT_z4)
An AC30 (at least a good, old one) is definitely a little more forgiving of this as well. I think what I said does hold true in most situations though. Try running a Memory Man through the front of a raging Marshall or, like I've done, a Trainwreck Express. You probably won't like it much! :)
Andy
If you don't use a lot of distortion you can get away with the delay first in the chain. A lot of the 60's guys plugged echoplexes into the front of their amps. Check out "James Gang Live" for an example. (In that case a lot of the echo was used for "freak out" stuff, not necessarily in a "musical" way like the syncopated stuff Edge and Gilmour do.)
There's no hard and fast rule for anything and you should always experiment. However, you'll find that putting the delay behind the distortion gives you a "cleaner" and more controlled sound, independent of the amt of distortion you use.
Quote from: DougH on January 19, 2009, 09:56:20 AMThere's no hard and fast rule for anything and you should always experiment.
So true - I put my compressor (Ross inspired) AFTER all of my distortions. This goes against nearly everything ever written down about where to put a comp in the chain.
HOWEVER, in a live, paying, I'm-playing-with-other-people-on-a-stage-not-in-my-boxers-on-my-bed, situation, it was indespensible for keeping my clean and dirty rhythm tones the same level on stage, allowing me to kick it off for my solos at a higher level to cut through the mix.
Is it an ideal situation tone-wise? No, maybe not - though I didn't notice that as much as those I was playing with, and especially the soundman, would have noticed the jumping levels everytime I wanted a different tone - and the overall quality of the SONG and PERFORMANCE by the ENTIRE band is more important than any ethereal, perfect, rhythm tone I could create - especially if getting that tone meant degrading the whole.
In my opinion, anyone who proclaims a 'rule' of any sort in relation to music is admitting that they are looking backward - music is about innovation and change. But then we ARE guitarists, most of whom would spend more time, and be genuinely more interested in, the manufacturer and specific model number of a germanium transistor than a new tone control topology...
Regards,
Jay Doyle
Getting back to the thread topic, I much prefer a fuzz followed by the treble booster, especially if you have some way of controlling the amount of low end cut on the TB... I like a pot better than the more common switch that chooses different input caps. Anyway the reason I prefer it is that fuzz can get kind of tubby and flat and gets lost in a live playing situation... the TB adds a little mids and can be set to perfectly attenuate the low end of the fuzz. On the other hand, I think a TB going into a fuzz sounds like crap, at least it does with my pedals. Also I have some buffered pedals later in the chain and it doesn't seem to be hurting anything... go figure.