New at runoffgroove.com: The English Channel

[Paul Marossy]

According to some articles I have read, the only place where tubes really matter is in the output section of a guitar amp. I have seen some amps designed like this - Peavey has at least one amp that uses that topology.
I'm sure someone could come up with a killer DIY hybrid amp.  

[petemoore]

The Runoff Groove project articles are great reads.
 By looking at the many schematics, it's great  reading the accompanying texts, And...listening to the SoundClips!. visiting Runoff Groove gives a hands on feel to the learning experience.
 From the Fetxer Valve to all the amp sims, experiencing the information in the well presented articles allow me to compare schematics, sounds, and commentary. It really enables 'reading between the lines of the schamtic with the reverified cuase and effect comments and soundclips.
 It's too kool just looking at the way the amps are basically laid out !!!
 It shows to go there are many ways to do it.
 Well I'm torn between the Matchless, the English Channel [a long ways across ], and the Supreaux.
 I'ts hard to tell exactly from the soundclip what the x effect will sound like through 'your amp...but they can be listened to and 'altered mentally' or adjusted for...if you know your amp real good and have been using the soundclips so your sort of familiar with building for it...I think they really help give a reference point to what's up with X effect!
 I think the EC soundclip is very well done...nice arrangement!
 what with the output at ROG, I want to give you a hye..your kickin my ass with all this!!!...I'm going to have to start a Jfet Farm...

[David]

Oh, masters of amp simulation:

We insist that you can't do another simulation project until you create a PIC-based front end to select a simulator and feed its output to a power amp.

This would be the height of DIY amp simulation! We could put ALL those simulators in one box and bounce back and forth between them!

Just zoomin' you, guys!

[RDV]

Although I'd never say anything was "the cat's pajamas."  :wink:

How's about: 'The Bee's Knees'.

Regards

RDV

[Gary]

We insist that you can't do another simulation project until you create a PIC-based front end to select a simulator and feed its output to a power amp.

We'll leave the switching system up to anyone that wants to tackle it.  Maybe include a power amp of some sort?

This would be a great project for one or several of you to take on.  Any takers?

[Gringo]

Maybe include a power amp of some sort?

This would be a great project for one or several of you to take on.  Any takers?

Maybe Joe D's vulcanized power amp (when he comes up with the high output one)

[Ge_Whiz]

In the words of the late Douglas Adams, "The Wasp's Nipples".  

[free electron]

We'll leave the switching system up to anyone that wants to tackle it.  Maybe include a power amp of some sort?

This would be a great project for one or several of you to take on.  Any takers?

hey! I have my old switching project laying somewhere in papers. It was before the time i started to play with uC, so no programming, only TTL & CMOS. Never bulit, but simulated and it worked. Maybe could be useful.
The circuit is not very complicated, I used 8bit priority encoder 4532 latched by 74ls75 to get binary code from input pushbuttons. That gives us address for  1to8/8to1 analog mux/demux. One mux/demux pair for switching effects, additional mux for LEDs... I'll post the schematic of this idea soon.
Regards
Peter

[Fret Wire]

Brian and Gary, have you, for testing purposes, been measuring your trimmers after you've set your bias?  I imagine you use 100k to cover all the variations in specs of 201's & mpf102's.

So far, I've been using reg. 100k lin. pots to set the bias, measuring, and putting in the nearest value resistor. I haven't hit over 50k yet with MPF102's. At least with my current batch. Trimmers are a godsend though. Since the size and price of 50k & 100k trimmers is the same, it's probably safer to go with 100k, and not have to worry about the variations, plus a dose of Murphy's Law.

I guess I just answered my own question, but I'd like to hear your thoughts on that. I like the Piher round, horizontal-mount (laydown), vertical adjust trimmers. You see these on MXR Phase 90 reissues and the like. They have a small footprint, and seem to have decent quality. I think I'll do the legwork and find out the exact part numbers, then post them if anyone is interested.

[B Tremblay]

Yes, the drain resistance is usually pretty low with MPF102 and 2N5457, but can be quite high for J201.  100k covers all the bases (hopefully) for most FETs that people may want to try.

I've measured the resistance at times, but since it is so relative to that specific FET, decided it's not the most valuable information.

The trimmer footprint I now use for the perf layout has a generic spacing, which will allow use of the Small Bear or RadioShack trimmers without too much hassle.

[Gilles C]

Wow again!

Last week, after a few testing with a smaller amp to carry with me, and going back to my Hot Rod Deluxe, I decided to stay with the HRD.

I still love the sound more than anything else, and my back seems to be able to support more than in the last years. It's getting better cause my HRD seems lighter in weight than before.  

Anyway, as someone said,  I could use the power amp section of the tube HRD, and change the preamp section to sound more like a Vox, Marshall, or else, when I want to.

And, good news for me, I'm almost assured to go back to the evening shift  at work. And that means I would be able again to build effects (or simulators, now...) in my iddle time, which I don't have right now on the day shift. It means, making a pcb to build the English Channel, etc... I really prefer pcbs (me too...)

>>>We insist that you can't do another simulation project until you create a PIC-based front end to select a simulator and feed its output to a power amp. <<<

>>>This would be the height of DIY amp simulation! We could put ALL those simulators in one box and bounce back and forth between them! <<<

Agreed... That's what I would like to do... I have my PIC based switching box waiting to be finished.  :twisted:

Keep on bringing your nice designs guys, it's very inspiring.

Gilles

[David]

HEY, GILLES!

How close is that thing to being ready?   :twisted:  :twisted:  :twisted:

[Gilles C]

Check the PIC project nfo in this page.

http://members.tripod.com/gillcar/id19.htm

When I had to put all my projects in boxes 2-3 years ago, when I started on the day shift, the PIC switch was working. But it was popping when I was switching the 5053 analog swithes.

I had resistors on the in/outputs, and the dc level for the analog switches was 4.5V

I was controlling the sequence "A only, A to B, B only, B to A, etc...) with one foot-swith, and the with/without effect with another foot-switch.

The PIC software was working well, but the popping was my only problem. It shouldn't pop, but it does??? That's where I stopped.

My goal was to have a pcb layout for the PIC swithing section (to be able to change the swithcing order easily) and another one for the analog switches (for the switching itself).

I also have a footswitch in a separate box (à-la-Fender amp...) that I would like to connect just like the foot-switches we use with amps. With a stereo 1/4" plug to connect it to the switch-box.

Oh, and now, I would like to add a preamp/simulator inside the same box  :wink:

[R.G.]

To get the 4053 to not pop:

- terminate the inputs and outputs to half the total power supply on the chip with 100K to 1M. The lower the resistance, the lower the chances of popping happening. Terminating the output of the effect in 100K is a really good step forward.

- watch your grounding. If the switch transient current from switching the chip flows in the analog ground line, you will have a pop that cannot be removed. This is layout determined, not circuit determined. It's best if there is an analog ground, and a digital ground, and they meet only one place, at the CD4053.

[petemoore]

And to who it may concern...
 To save on trimmers, buy a batch of 100k's and hook wires to them for use as Variable resistor, then use that to find the Drain resistor value for your Fet's...I just 'socket' the end of the 100k's wires...actually I tin the ends, then tape them on a slotted piece of popsickle stick...poke that in the Drain R socket holes...or connect temporarily somehow...then try your Jfet in that position, then measure and replace the 100k pot with a fixed value.
 I've been getting so many 100k trimpots from these VCR's and Puter monitors, I've just been installing them and leaving 'em in there.
Very kwik, EZ, sure fire...there ARE yes differences from on Jfet to another, having extras is a 'helpful thing when using them, IME.

[Gilles C]

I think I started with 1M and went down to 330K for the pull-up resistors, with half the supply (4.5V) on the IC. I didn't want to load the guitar with a too low impedance input, so I don't think I went down to 100K.

But the idea of 2 separate grounds could be it.

I'll take the unit out this week and check what I have down with the ground itself. I think I have a large commun ground  :roll:

Thanks R.G. for your suggestions about the PICs... again  

[StephenGiles]

It's worth bearing in mind that this stretch of sea can be very rough, very rough indeed, as I have experienced on a few occasions. However, rough this design is not! It sounds very good indeed. I might even lurch over to Maplins on Croydon to buy some FETs.

[Ge_Whiz]

I might even lurch over to Maplins on Croydon to buy some FETs.

No! Don't do it! Get a Rapid Electronics catalogue and buy twice as many for the same money! //www.rapidelectronics.co.uk

[RDV]

I thought I would give my impression of this little buggeroo. I tried my English Channel through a big amp for the 1st time last night. I used it at a rehearsal with my old dull sounding 84' Peavey Bandit 65. It really sounded wonderful, so nice and bright and tubey sounding. I don't know if it'll work with my JCM900( I guessing that it may be too bright) but it's definitely found a home with my rehearsal rig! I ran my HMP into it for high-gain leads and it was downright psychodelic! I would recommend this one to anyone looking to brighten up a dull sounding SS amp. I'm tempted to gig with this and my old Bandit it sounded so good!



RDV

[Lonestarjohnny]

Ricky, now you see what i'm talking about on the old Peavey classic of mine, these Emulater's sound very good right through the front end, can't wait to get the Mace and my Multi/Emulater board going,      
Johnny