http://i1108.photobucket.com/albums/h408/7Ambo707/HPIM14051_zpsf27732c2.jpg
http://i1108.photobucket.com/albums/h408/7Ambo707/HPIM14071_zps9764c030.jpg
Schematic and layout are in the description of the video as well. If you feel like building it yourself please do. Its great for room volume noodling. about like a tv at normal volume. you can still talk and have a conversation while playing. Just thought some of the low voltage tube peeps on here might like it. I dont have a bom drawn up or detailed instructions but will have them posted soon. I plan on doing a construction vid of this kit this week sometime.
Cheers,
Greg
That sounds pretty damn good to me...
Some suggestions:
Use a "proper" SMPS, something like this (http://i210.photobucket.com/albums/bb292/frequencycentral/555SMPSNegative33.jpg). It gives the option for higher voltage (more output, more clean headroom) and is regulated (note the feedback with the voltage divider to the base of the transistor).
If you have a 12AT7 lying around, give that a try in place of the 12AU7. You'll get slightly less output but more distortion and the distortion will sound different
Bypass the cathode resistor of the 12AU7 with a capacitor, say 47uF. You'll get more output and more distortion.
All of the above are true, however, I was trying to make an amp that was quieter than normal for indoor, late night use. Also wanted to keep the voltage low for first timer tube folks. something like a step up after the valvecaster. Nothing to advanced or scary. I also wanted it to be a bit more on the clean/break up cranked old school sound. I figure everyone has a tube screamer or some boost pedal that will make it distort if they want. I get the most comments and requests for this type of amp and had never put it into kit form or offered it before. I finally caved in and this is what I settled on. I just wanted to make the schem etc. available here for the diy crowd thats helped me get started. I use the 1363/4 smps when i want higher voltage and some 30 to 50 ma. any more than that I just use a power xformer.
And btw thank you! I hope I didnt sound snooty or anything :icon_redface:
That's great! I already have a Firefly but building one of these seriously tempts me.
Well done, Zambo! Sounds nice! I love those little tubey projects...each one seems to come with its own personality, and yours does too!
Shoeman, you north, mid or southern Maine? I'm over in the mountains near NH....cold winter, isn't it? ;o)
Nice! What's the name of the project?! It has to have one!!! is that a 1054 as a multiplier!?
I've never studied that sort of PS design. Any threads here we could reference? GibsonGM, I'm in Bangor, and yeah, it's been cold. Best time of year for electronics projects though.
I always called this amp The Gooneybird .... long story... Still open for names lol!! This is a LT1054 voltage multiplier that I borrowed from The Murder One by Frequency Central. It puts out the right amount of voltage and the 1054 puts out a lot of milliamps . Ive had one up around 120 volts with no issues. Its more sturdy than the max1044. To be honest I only half understand how it works. I believe Frequency Central (aka Rick Holt) designed it. Many thanks to you FC!! I have used this on so many different tube projects its silly. I built 2 or 3 just to use as prototype power supplies.
Any problem with just plugging in some headphones?
I tried it and it was remarkably underwhelming. the headphones lived though. I would think some dropping resistors and a headphone jack would be good though. Like a 47k in series from + lead on the speaker jack to the + headphone jack and a 1k pot from + headphone to ground lug on the head phone jack. that would give you a reduced signal to headphones with a volume control. I dont know what actual value the series resistor would need to be and you would also need a dummy load for the speaker jack while its un plugged. I think a 10 ohm 5 watt resistor would do the trick without getting to hot. Ideas anyone?
that sounds really good man
keep it up
Quote from: zambo on January 29, 2014, 04:50:24 PM
Ideas anyone?
Plugging ordinary headphones into a scaled down guitar amp output isn't going to sound at all the same as having the amp plugged directly in to the speaker. The headphones, to start with, don't have the same frequency response as a guitar speaker, so will sound very different. Also, a speaker is an inductive load, and has an impedance that rises with frequency. This also means that the output valve sees an impedance that rises with frequency, which is an effect you won't get as much of loading the output with just a plain resistor.
Your idea with a dummy load+series resistor would work fine, if you really wanted a headphone output. A 10 ohm, 5 watt (1 watt would probably be fine with an amp this size) resistor would work well as a dummy load, but 47k in series with the headphones would be WAY too high. Don't forget that the resistor and the impedance of the headphones (32 ohms is pretty common, IIRC) form a voltage divider, and the output of your amp is not particularly high to begin with. Try 33 ohms in series with the headphones, and if it's too loud, increase the value, if it's too quiet decrease the value. You could also consider adding 330uH or so inductors in series with the dummy load and the headphone+resistor string. The inductor would make the headphone load "look" a little more like a speaker to the amp.
You might consider adding something like this (http://www.aronnelson.com/gallery/main.php/v/DougH/amp/Firezog.gif.html) rather than/as well as a headphone output.
Yeah the Firzog is perfect for that! Thanks phsycedelicfish!! I forgot about that one. Will it still drive headphones? I guess it would and if it was lacking volume you could start changing the 150k series resitor? I still think someone needs to develop guitar specific headphones. dont know what it would take but I think you could sell a but load of them instantly and every christmas after that!! Maybe I will take some cheap ones and cover the speakers with light glue or something. I wonder......
150k is way too high for a series resistor, and a 1M pot won't be much use anywhere below max.
When you tried headphones before, was the volume level OK? If the volume was fine, or slightly too loud, try running the headphones in parallel with a 10 ohm or so dummy load. If you want it to sound more similar to a speaker, then connect the line out of the firezog to a cabinet simulator and then into a headphone amp. For cabinet simulators, try this (http://www.runoffgroove.com/condor.html).
PS: a 240V:5V mains transformer can also be used for the output transformer, if anyone is wondering
The volume seemed pk but my headphones have a volume control. not sure how it works on those. sound was blah though. Love the cab sim you mentioned. Might have to build a pcb. it would be nice if someone built a reactive dummy load with cab sim and headphone out all in one box. that would solve a bunch of problems all at once.
It would be nice, but it would be incredibly difficult to do from a design perspective without active circuitry. If you wanted it to be nice and small, you'd need the active circuitry to be solid state. This sort of thing has been done with valves, but all the designs I've seen have been big and expensive.
Thank you Greg, brilliant as always! I only have a PP OPT around, can I use a PP design for output?
I like the sound of this, and happens to have a 12au7 and a 12ax7 tube lying around, so I might get to it eventually.
I look forward to some more instructions and advice. Would love hi-res gut shots too.
@ Sajy - yes you can. and it sounds great as a push pull. you build it the same except for the opt you put one wire on plate a and the other on plate b. voltage goes to the middle. also instead of hooking the grids toigether one gets grounded. its just like the firefly at that point. http://ax84.com/media/ax84_m276.gif Learned most of what I know playing with firefly schematics. Long live DougH! Let me knbow if you get stuck, glad to help :)
Thanks alot Greg.
I found the correct Hammond OT in my stash today. I have a bunch of terminal lug strips too. All I need is the tube sockets, the LT1054 and a few of the caps and I'll be building one of these next. Gooneybird..... Hmmmm.... not very elegant ;D
I'm very new to this but this is still possibly stupid question,
What OT is that? and what diodes are the ones in the power supply?
I'm planing on building a project soon, currently a tube cricket /w bridged LM368s, active 3 band EQ and a lot of small mods. But if this is in the same price range I'll build this instead.
Thanks in advance ;D
Quote from: solderburn on February 03, 2014, 04:17:19 PM
What OT is that? and what diodes are the ones in the power supply?
The OT is any transformer that with its secondary connected to an 8 ohm load will have a primary impedance of roughly 20K. A fender reverb transformer will work well, and I suspect this is what Greg used. A 240:5V mains transformer will work as well. You can also use any of the hammond 125*SE transformers if you connect an 8 ohm speaker across the black and orange leads. The power rating of the transformer shouldn't matter too much, this amp probably puts out less than 500mW (0.5W).
As for the diodes, 1N400X would be good, I'd go for 1N4004. They all cost the same, though, so it doesn't matter too much.
Quote from: psychedelicfish on February 03, 2014, 05:27:25 PM
The OT is any transformer that with its secondary connected to an 8 ohm load will have a primary impedance of roughly 20K. A fender reverb transformer will work well, and I suspect this is what Greg used. A 240:5V mains transformer will work as well. You can also use any of the hammond 125*SE transformers if you connect an 8 ohm speaker across the black and orange leads. The power rating of the transformer shouldn't matter too much, this amp probably puts out less than 500mW (0.5W).
As for the diodes, 1N400X would be good, I'd go for 1N4004. They all cost the same, though, so it doesn't matter too much.
Will a Hammond 1750A work?
Datasheet link:
http://www.hammondmfg.com/pdf/EDB1750A.pdf (http://www.hammondmfg.com/pdf/EDB1750A.pdf)
Sure will. 22K primary and 8ohm secondary is perfect. I have the same tranny I'll be using for my build.
Awesome! Hopefully I'll get the parts in the next couple of weeks.
lol!! Ive made these with a 1k/8 ohm audio trans from radio shack quite a few times and never melted anything. The correct one is the 22k reverb or line trans, but it only has 60-70 volts going through it. I used the reverb trans in the kits because I know it wont melt. the 3 dollar rat shack pp trans does work though.
keep in mind though, i just came home from work after drilling a 1/4 inch hole in my hand......Not to be trusted... :icon_sad:
Ouch!
Two more quick questions, Can i use 1/2w resistors? And will 24v caps work for every thing other than the power supply caps?
you can use 1/2 watt resistors. i use a heavier watt cathode r though. 2 watts that i have around. use caps at least 100v. safety margins are good. cathode bypass caps are 25 volt electrolytic. all others should be 100 or up. the diodes i used are 1n4148 btw. i revised the board to be a bit better and added a fe reservoir caps to cure some of the sag. just a bit. will post new pics asap.
Thanks! now i have all the info that in need, Btw your guitar playing in the video is fantastic!
Hey thanks! I havent been doing enough of it latley so thats good to hear ;D
I can't wait to see new schematic, Btw how about biasing second preamp stage with a 47K Ra as merlin suggested in his book?
I will leave the schematic the same except for the reservoir caps being added. Changing the plate resistor to 47k would be a simple thing though. I am actually going to take this kit I am starting so I can film and photo the build and modify it afterwards to have a treble and bass only eq with bright switch. I may also modify it to have an el84 or 6v6 ( will have to swap ot out) but still run it at low voltage. I think it will still work.
Quote from: zambo on February 04, 2014, 01:47:41 PM
I will leave the schematic the same except for the reservoir caps being added. Changing the plate resistor to 47k would be a simple thing though. I am actually going to take this kit I am starting so I can film and photo the build and modify it afterwards to have a treble and bass only eq with bright switch. I may also modify it to have an el84 or 6v6 ( will have to swap ot out) but still run it at low voltage. I think it will still work.
That's a good idea. Can this supply handle PA section powered by el84?
And one other rookie question: Can I use this type of supply for getting more voltage? I'm trying to build a 4 stage 12AX7 overdrive pedal and cannot find a good PS, I've tried 555 smps but I got only oscillations and fried MOSFETs! I just want about 150V @ 6mA. Please help me through it.
Thanks
you can make this supply do it, you just need to make sure the supply caps are of the right voltage. So at the end of the power supply you will be using 175 to 200 volt caps. You could use a 1363/4 smps from taylor electronics and get 150 up to 200 volts pretty easily. you just have to load it down enough to not whine. Oscillations usualy mean you need to use sheilded wire for the signal path. there are a lot of reasons but thats a big one. the 555 should work but i have always used the 1363. 12ax7 will run fine at 100 volts. you could built this supply using 19 or 21 caps and get 100 volts. it would just be biig.
Thanks for the quick reply, unfortunately I don't access to Tylor Electronics, so I guess I need to buy lots of 10Us and 4148s...
Thanks again Greg.
if you have access to step down transformer they work to. a 120 to 12v coupled to a 12v to 120 for b+ works well from what i hear. i havent tried it yet but should.
Do the tubes glow? ;D
Frequency Centrals murder one glows, but with sublimini tubes. I dont know if the bigger tube means less/no glow.
Here's a thought I just had for an alternative power supply for this mini amp:
If you used a 24v+24v 12VA PT, wired it for a half-wave voltage doubler from rail to rail (that is, grounding one of the 24v leads and feeding the doubler with the other one), and connected the 12AU7 and 12AX7 filaments in series (wired for 12v), you could use the center tap to feed the filaments, and the voltage doubler would give you over 130v unloaded (probably more if you use large values for the voltage doubler and filtering caps).
What do you think? Worth a try?
[EDIT]
Here's a schematic to help visualize what I meant: http://imageshack.com/a/img855/7152/4wu0.png
Quote from: zambo on February 07, 2014, 01:21:54 PM
if you have access to step down transformer they work to. a 120 to 12v coupled to a 12v to 120 for b+ works well from what i hear. i havent tried it yet but should.
Thanks, that would be something like Real Mc Tubes, but I don't want to use transformers becouse of their weigth and size. How about a SMPS design using LT1054?
@ solderburn- they glow but not a ton. led light in the center of the socket works good though.
@ Blackcorvo- Sounds good, but when the voltage goes above 70v or so they get to loud for a quiet amp all of a sudden.
@Sajy ho- thats what the current ps is. you could use smaller 10uf 100v caps, just dont add more stages to it or you could have a blow up. I only used 160v because i was selling them to someone else. more of a cover your a$$ type of thing.
Quote from: zambo on February 09, 2014, 02:00:56 PM
@Sajy ho- thats what the current ps is. you could use smaller 10uf 100v caps, just dont add more stages to it or you could have a blow up. I only used 160v because i was selling them to someone else. more of a cover your a$$ type of thing.
:icon_mrgreen: Sorry my bad, I thought SMPS is only called for those with a MOSFET switch!!
I wouldn't say this is a SMPS, it's a charge pump or switched capacitor voltage converter if anything.
Frequency Central did a SMPS design using a MAX1044 if you search the forum.
Quote from: Scruffie on February 10, 2014, 03:51:25 PM
I wouldn't say this is a SMPS, it's a charge pump or switched capacitor voltage converter if anything.
Frequency Central did a SMPS design using a MAX1044 if you search the forum.
It is an SMPS in a sense, because it does chop up the DC input at a high frequency in order to convert it to a higher voltage. It differs from a boost converter in that it increases the voltage by putting the chopped up DC through a voltage multiplier rather than pulsing current through an inductor.
A boost converter would be better, I think, because the output would be regulated, but the current design is simple enough and seems to work fine.
i still hope for some gut shots.
Quote from: zambo on February 09, 2014, 02:00:56 PM
@ Blackcorvo- Sounds good, but when the voltage goes above 70v or so they get to loud for a quiet amp all of a sudden.
You could always just make it a half-wave rectifier instead, still using both 24v leads to get 48v AC. I'm guessing it would give a B+ of something around 60v.
How are the Power supply caps supposed to be oriented?
I have Polarized capacitors, Will they work, and if so how am i supposed to orient them? ???
Anything?
Quote from: solderburn on February 18, 2014, 05:53:42 PM
How are the Power supply caps supposed to be oriented?
I have Polarized capacitors, Will they work, and if so how am i supposed to orient them? ???
All the upper lids in the schem are positive. Something like this:
http://i210.photobucket.com/albums/bb292/frequencycentral/ValvecasterHead.jpg
yes exactly like that. thats the exact power supply. Thank you Sajy!
I got the voltage multiplier to work with polarized caps the other day and today I wired up the rest of it, and I Works!! :icon_cool: Sounds like a crunchy Marshall.
The sound is great accept it has absolutely no headroom. It instantly clips, But I play Hi gain stuff mostly but for the sake of versatility how could I decrease gain without affecting volume?
And when I play a chord, say a G major or E 5 It has a extreme loss of volume, kinda think a wire might be loose. Is there anything else that would cause this to happen?
Id like to fix these problems soon because I did not paint the chassis :icon_rolleyes: So, I have to disassemble a lot of it. and Id like to have the peace of mind that i got all of the issues worked out.
Ill post pics when I'm done too!
Hi,
i have build a similar amp with the same problem, I think the problem is that the charge pump can't maintain the B+ voltage because bassy notes require more current to move the speaker.
Try to play very agressive but only hiting the sixth string and you will see the same thing happening, and the sound getting louder after that. I don't know if that's was sag supposed to be, but my amp bass gets really flabby.
Look for the voltage at the charge pump and if all the capacitor's are working properly, maybe adding a larger reservoir capacitor will correct that.
At lower volume setting the problem disappear right?
I tried again, had the same problem and wiggled a cathode wire by accident, And it fixed volume loss the problem accept for when i plugged my homemade Telecaster in(tuned to E with single coils) and ripped on the low e string it lowers the volume a little bit, not much. Which is weird because i plugged my strat knock off in (modded with humbuckers and tuned to Eb) ,Dean ML (also with humbuckers tuned to A#) and my bro's Epiphone (P-90s tuned to D) there was no volume loss, but with the Dean it was a little flabby, i think i can facilitate this by changing the cathode capacitor somehow. I made a Big Muff Pi and had almost the same problem, then re did the off board wiring thus fixing it. I narrowed it down to adjusting cathode caps and poor off board wiring.
But still the lack of headroom is a little annoying.
Adding a reservoir cap will help the volume sag a ton! I noticed it on mine when its cranked ( hahaha cranked ...) all the way up. a 20uf worked. I dont play it turned all the way up though. im a halfway guy and use a pedal for super gain. If you want more headroom, dont bypass the cathode on the power tube. It will distort less. you wont notice a ton of volume loss. If you want more headroom, you need more voltage. thats all there is to it. Im going to modify one to use this voltage but use an el84 power tube. I dont know if it will work out well but... yeah. im going to try it any way haha. If you just gotta have more headroom and you used all high voltage parts, the 13 dollar 1364 smps from taylor electronics works and has enough ma. still needs the reservoir caps though. Remember, this was built for quiet nighttime practice. Borderline headphone material.
Quote from: zambo on February 22, 2014, 11:39:43 AM
Im going to modify one to use this voltage but use an el84 power tube. I dont know if it will work out well but... yeah. im going to try it any way haha.
I've tried something like that on my breadboard, only using a 6AQ5 (7 pin mini 6V6 equivalent) and a 32V supply. It worked, and more importantly sounded good, but the volume was a little on the low side (ok, scratch that, it was a lot on the low side). With your 62V supply you should have no problems with volume. I think a 5k load should work nicely, but you should play around with this if you can. At this low of a voltage you don't have to worry too much about the valve's max dissipation, and I seriously doubt your supply can put out 12W to overheat the anode anyway.
Hey,
why don't you use a Max1771 circuit instead? 240V and it's pretty loud;
I made one, and it's too loud to crank at night, but headroom is a little better.
take a look:
(http://i1303.photobucket.com/albums/ag159/Thomas_Eduardt_Hafemann/ObsessionSchematic_zps0cd78dc9.png)
Based on Frequency Central Obsession amp
I reinstalled it yesterday and gave it a good testing today and both problems i had before are fixed! They where caused by bad terrible off board wiring. I was excited to see what it sounded like and went way to fast. But i re wired it and all is good, It sounds great!! no headroom issuses or volume drop. I'll post pictures tomorrow. the only two anomaly's are when i plugged my strat and tele in the low end is flabby/farty, but when i tried a LP with P-90s (tuned WAY lower i may add) the flabbyness was eliminated. OD did Stop the flabbyness with the strat and telecaster. Could this be fixed by adding a buffer or by changing Cathode cap values? And when i drive the amp hard with a pedal and take my hands off the strings it makes a for a lack of a better term a hissing/tire deflating noise. his one has me stumped. Both of these minor issues don't really bother me cuz it sounds so good with a little OD, but i would be nice to fix'em.
thomasha- Thanks for your suggestions! the BMP tone In the circuit gives me ideas! And did you make the amp in the video? it looks great!!
And thanks zambo! this is by far my best piece of gear I have ever made! :icon_mrgreen:
Thanks again zambo!
(http://i95.photobucket.com/albums/l148/permanent2112/Mobile%20Uploads/IMG_20140223_150506_zpsdddbf953.jpg)
In the spring I'll put finish on it. If i can remember to.
Now hears a gutshot (sorta). hard to see because of the multiplier caps. all of the parts are placed randomly as you can see. this is my third or fourth project. first in a long time actually.
WARING TERRIBLE SOLDERING SKILLS IN FOLLOWING PICTURES
(http://i95.photobucket.com/albums/l148/permanent2112/Mobile%20Uploads/IMG_20140220_155404_zps5df07afa.jpg)
(http://i95.photobucket.com/albums/l148/permanent2112/Mobile%20Uploads/IMG_20140223_150912_zps8acfbb18.jpg)
Quote from: thomasha on February 22, 2014, 11:07:19 PM
Hey,
why don't you use a Max1771 circuit instead? 240V and it's pretty loud;
I made one, and it's too loud to crank at night, but headroom is a little better.
take a look:
(http://i1303.photobucket.com/albums/ag159/Thomas_Eduardt_Hafemann/ObsessionSchematic_zps0cd78dc9.png)
Based on Frequency Central Obsession amp
Nice, Unfortunately I can't find MAX1771 anywhere! In the LT1054's datasheet was mentioned that it can deliver 100mA too; so why not design a SMPS with that instead of MAX1771?
Solderburn- I love it! I am glad you got it working! I love the enclosure! Thanks for posting the pics :) Glad to give back!
@ Thomasha, Thats a sweet sounding amp! Ive built them around 200 volts with 1363 a lot of times and various versions and spinoffs of the firefly and 4-4-0. all of them are to loud. great headroom etc. but i always end up turning them up to the its to loud point. I saw Frequency Centrals post about turning your valvecaster into an amp. he stated voltage equals volume. I have lived by this mantra ever since. Most of my bigger amps (18 watts usualy) I build with a vvr inside to drop the dc rail for a master volume. This one seems just loud enough to be usable at night or around people talking etc. about like an acoustic guitar.
How many ma does the 1771 put out? I would love to try and build with one! I may try a push pull 6v6 amp with the LT1054 just to be ridiculous ::) I have one I can wire it into just to see.
here is a gutshot of an incomplete one. I will try to post a done one pretty quick here. (http://i1108.photobucket.com/albums/h408/7Ambo707/022414131212_zpsdacd7721.jpg) (http://s1108.photobucket.com/user/7Ambo707/media/022414131212_zpsdacd7721.jpg.html)
I still have to solder in a bright cap on the volume pot, but here it is right before testing it.
(http://i1108.photobucket.com/albums/h408/7Ambo707/022414210252_zps15b58d6f.jpg) (http://s1108.photobucket.com/user/7Ambo707/media/022414210252_zps15b58d6f.jpg.html)
Quote from: zambo on February 25, 2014, 01:02:31 AM
I still have to solder in a bright cap on the volume pot, but here it is right before testing it.
(http://i1108.photobucket.com/albums/h408/7Ambo707/022414210252_zps15b58d6f.jpg) (http://s1108.photobucket.com/user/7Ambo707/media/022414210252_zps15b58d6f.jpg.html)
Is it a new one?
I had a question; Why to use 22k OPT? two sides of 12AU7 are in parallel connection, so each of them will see twice of the load impedance. I have a 7k-5R OPT from an old Grundig radio, if I use it with 8 ohm speaker it'll give me about 11.2k load impedance; so can I use it instead?
Thanks
Sajad
Quote from: sajy_ho on February 26, 2014, 01:38:54 AM
I had a question; Why to use 22k OPT? two sides of 12AU7 are in parallel connection, so each of them will see twice of the load impedance. I have a 7k-5R OPT from an old Grundig radio, if I use it with 8 ohm speaker it'll give me about 11.2k load impedance; so can I use it instead?
Thanks
Sajad
22K:8r is a (relatively) common transformer, it comes in the form of a reverb transformer. I suspect this is why Greg used one. At this low of a voltage, you don't really need to worry much about what load you use, so your radio transformer should be fine.
Quote from: psychedelicfish on February 26, 2014, 01:42:02 AM
22K:8r is a (relatively) common transformer, it comes in the form of a reverb transformer. I suspect this is why Greg used one. At this low of a voltage, you don't really need to worry much about what load you use, so your radio transformer should be fine.
Oh, now I get it! so as long as my load line does not go far the tube limits I can use any transformer.
Thanks man.
Exactly! At this low of a voltage you could pretty much use a meatball and some duct tape and get it to work ( grass fed organic beef of course ) . As I said before I used a small audio trans from radioshack that is 100k to 8 ohm and it worked fine. 3 bucks well spent? Your radio trans will work great. Use it in push pull like on the firefly and it will sound as good as any of these little tiny amps. You can also get crazy and make it with an eq etc. it does work. another tube stage would help that too. This amp that i put gut shots of was finished last night. it sounds pretty good. I put a 250pf bright cap across lugs 1,2 of the volume pot. I also added 2 10uf reservoir caps to help the sag. it worked well. I will post some vid clips later if i can get to it.
Hi, it's me again; with another issue! I've built the PSU and added some more stages to get about 100 volts. My problem is finding a SE OT, I'd just found a PP transformer around,(I'm living in the middle of nowhere!). So what do you think? Can I use this PP transformer (7k-5R rated at 40W and weights like a ton!) in this parallel SE design? or the transformer's core will sature and make noise?
And I don't know how to bias a firefly type self-split output stage, so I caould go for a PP stage.
Please share your knowledge.
Thanks
Sajad
Might have been asked but what's the OPT input?
I believe they are referring to the Out Put Transformer. Some of the other terms are PP -push pull transformer and SE- single ended transformer.
lil while back I found this guy on ebay selling what looked like decent transformers for a decent price
http://stores.ebay.com/musicalpowersupplies/
http://www.musicalpowersupplies.com/ordering/
I haven't tried any of them yet , so far I've only built a superfly with a hammond 125b.
So what's the Doreen e between OUT And OPT?
Quote from: sajy_ho on March 02, 2014, 05:14:51 AM
Hi, it's me again; with another issue! I've built the PSU and added some more stages to get about 100 volts. My problem is finding a SE OT, I'd just found a PP transformer around,(I'm living in the middle of nowhere!). So what do you think? Can I use this PP transformer (7k-5R rated at 40W and weights like a ton!) in this parallel SE design? or the transformer's core will sature and make noise?
And I don't know how to bias a firefly type self-split output stage, so I caould go for a PP stage.
Please share your knowledge.
Thanks
Sajad
Hey Sajy, use it. if its there just do it and see. i am sure it will be fine. big, but fine. use a 390 to 500 ohm cathode reistor. if you have a 1 ohm resistor put it in series with the power tube cathode resistor ( 1 ohm first then 390-500 ) . you can measure across the 1R in millivolts and that number is the milliamps your drawing. you can figure the bias from that. just use the firefly self split design and you should be fine. just follow the schematic. I believe it uses a 440 ohm resistor for the power tube cathode.that should be great.
@ Mustachio- I have heard those are decent transformers but never used them. I ccaros has and he makes good stuff.
@ Will- I dont know what Doreen e between input and output means. Sorry, Im may be dumb on this one.
Thank you Greg; I'll go with the Firefly and when finished will report the results...
Thanks again
Sajad
Quote from: sajy_ho on March 03, 2014, 04:39:17 AM
Thank you Greg; I'll go with the Firefly and when finished will report the results...
Thanks again
Sajad
I think the 7k:5R OPT you found would be an overkill for this project, see if you can find/salvage a small mains transformer say 120-0-120V (for 240V mains) to 5V or something close it, this will give you a good match for the 12AU7s and be much smaller than the 40W OPT.
Quote from: jazbo8 on March 04, 2014, 02:36:02 AM
I think the 7k:5R OPT you found would be an overkill for this project, see if you can find/salvage a small mains transformer say 120-0-120V (for 240V mains) to 5V or something close it, this will give you a good match for the 12AU7s and be much smaller than the 40W OPT.
Hey jazbo8, thanks buddy; That OPT is so old and the writings on it's secondary taps has been removed; the only writing has remained on the primary side says 6k.
The other day I measured turn ratio of that OPT using 3.5V ac on secondaries and measured 350V p-p, and 175V from center tap to each plate!!
The numbers are so extraordinary; so using 8R speaker, it gives me 80k P-P and 20k P-CT. So what do you think? That iron is faulty or it was designed for an exotit speaker!?
And also looking at its huge size I think it's core will not even get close to saturation with SE operation, so can I use half of the primary side(20k P-CT) for a SE amp?
Thanks
Sajad
100:1 turns ratio! That's an odd one, wonder what it was used for? ??? There was an interesting project using a PP OPT in an poor-man's UL amp (a la Dumble SSS) over at TAG that might be worth a look, with 40W you are not going to saturate it easily... another project for you! :D
There is an interesting page here:
http://diyaudioprojects.com/mirror/members.aol.com/sbench/50c5.html
on using cheap power toroids as audio output and input transformers. Most toroids have the equivalent of a very limited gap so push-pull is where they are best but some have significant binder thickness that translates into a larger gap and these are suitable for single-ended use. The 50C5 has a relatively low output impedance and will take a 2500 ohm output transformer, but a triode output should be lower. BTW the Steve Bench site is awesome for tube stuff. the Tubecad site is another good one.
Hi guys, here's mine:(http://i587.photobucket.com/albums/ss312/sajy_ho/23012012511.jpg)
(http://i587.photobucket.com/albums/ss312/sajy_ho/23012012510.jpg)
I did a few changes, raised B+ to 100V, added a simple headphone out:http://www.sophtamps.ca/images/headphonebox/headphonebox1.4.jpg
As I could find only a pp OPT, I'm using only a half of the primaris; so I used a dpdt to swith between Greg's amp and a pp class A Firefly type amp.
The sound is cool in SE mode, rich with harmonics and totally awsome, In the pp mod at high volume it sounds like a jtm45 fully cranked.
Maybe not the loudest but definitely the best sound of my gear! Thank you Greg
Sajad
Sweet! Thats a good looking amp! Would you mind posting a quick schematic for your amp switching between se and pp? thats very cool!
Quote from: zambo on March 08, 2014, 11:05:46 AM
Sweet! Thats a good looking amp! Would you mind posting a quick schematic for your amp switching between se and pp? thats very cool!
Hey Greg, glad you liked it:
(http://i587.photobucket.com/albums/ss312/sajy_ho/12.jpg)
Awesome! ;D
Soundclips please!
Quote from: thomasha on March 08, 2014, 12:26:58 PM
Awesome! ;D
Soundclips please!
Thanks, I wish I was a good player. :icon_rolleyes: I'll post a clip as soon as I find someone to play.
Quote from: sajy_ho on March 08, 2014, 12:02:13 PM
Quote from: zambo on March 08, 2014, 11:05:46 AM
Sweet! Thats a good looking amp! Would you mind posting a quick schematic for your amp switching between se and pp? thats very cool!
Hey Greg, glad you liked it:
(http://i587.photobucket.com/albums/ss312/sajy_ho/12.jpg)
Very clever idea! Been humming and haring over building another AU7 power amp build but I think this might make a project very much worth it.
Might be a good idea to make it an internal DIP to make sure it's not flicked when the powers on... seems like it might not be good for the tube/transformer.
I have a ton of 12au7s laying around, like 200 ish 100V 10uf caps, and around 100 diodes. I think this amp is definitely going to happen. Just waiting on an order of maxx1044 to get here. I'm sure I will have plenty of questions regarding this build when it finally gets started as I am new to diy amps and high-er voltage stuff.
For instance, can I split the 12V from a wallwort to power the tubes as well as the maxx, or do I need separate 12V sources?
Quote from: DefiantAudio on March 09, 2014, 01:06:47 AM
For instance, can I split the 12V from a wallwort to power the tubes as well as the maxx, or do I need separate 12V sources?
Of course you can, but that wall wart needs to be at least 1A.
I'm using a 12V-1A switching adaptor.
I built this over the weekend - my first amp build! Sounds good but I've got a couple of issues.
(https://lh6.googleusercontent.com/-BZTICAg4rHs/Ux1y8cOx52I/AAAAAAAAAP0/aNuaF-ocOXk/w759-h567-no/IMG_0061.JPG)
Yes, i did put too many turrets in!
There's a high pitched whine which is fine at about half volume but gets intrusive when it's cranked. Is this the charge pump? I'm using a 7660s. Anything I can do to reduce it? I've got an indicator LED and two 'tube glow' LEDs hooked up to the 12v supply as well (with 4.5k limiting resistors) - would this be an issue?
The amp seems to rely on a guitar with grounded strings to work properly - it's fine with my strat (as long as I'm holding the strings) but it buzzes like crazy with my Les Paul. Have I missed something obvious with the grounding? I've checked continuity of ground between input jack, output, power and board and all seems OK.
Any help/advice gratefully received - it's so close to being right it's frustrating!
Quote from: JustinFun on March 10, 2014, 04:22:43 AM
I built this over the weekend - my first amp build! Sounds good but I've got a couple of issues.
(https://lh6.googleusercontent.com/-BZTICAg4rHs/Ux1y8cOx52I/AAAAAAAAAP0/aNuaF-ocOXk/w759-h567-no/IMG_0061.JPG)
Yes, i did put too many turrets in!
There's a high pitched whine which is fine at about half volume but gets intrusive when it's cranked. Is this the charge pump? I'm using a 7660s. Anything I can do to reduce it? I've got an indicator LED and two 'tube glow' LEDs hooked up to the 12v supply as well (with 4.5k limiting resistors) - would this be an issue?
The amp seems to rely on a guitar with grounded strings to work properly - it's fine with my strat (as long as I'm holding the strings) but it buzzes like crazy with my Les Paul. Have I missed something obvious with the grounding? I've checked continuity of ground between input jack, output, power and board and all seems OK.
Any help/advice gratefully received - it's so close to being right it's frustrating!
I wish someone more knowledgeable like Greg would answer your question, but I think that whining you said is related with the chip you're using, replacing it with another chip that could handle more power(like LT1054) will help.
As for the background noise, using shielded wire in grid paths will help a bit. if you can't use shielded wire, adding a 10-68k grid stopper resistor before the first grid would help too.
^There's a high pitched whine which is fine at about half volume but gets intrusive when it's cranked. Is this the charge pump? I'm using a 7660s.
If the noise is coming from the charge pump (which it may or may not be):
Are you sure it is the 7660S and not the 7660?
If it is the 'S' model, do you have pin 1 connected to pin 8?
Thanks both.
Samhay: It's definitely a 7660s (unless it's an ebay fake - can't remember where i got these from, they've been in my stash for a while). Pins 1 & 8 are connected (I've just checked continuity).
Sajhy - are these the wires I would need to replace with shielded ones (highlighted in purple)?
(https://lh6.googleusercontent.com/-ukS5GAxA0AM/Ux3INkrV1UI/AAAAAAAAAQo/Jt4K9lQNMg0/w695-h521-no/43ab30af-bcfa-4ec9-b191-6c3b9b04f278)
Not sure if this will solve my problem though, it feels like something is up with the grounding - when I'm using the Les Paul the buzz goes away if i touch the enclosure.
Quote from: JustinFun on March 10, 2014, 10:26:47 AM
Sajhy - are these the wires I would need to replace with shielded ones (highlighted in purple)?
Yes exactly those wires, plus the one comming from input jack (green) and those two green wires connected to tone and volume. Don't forget to connect ONLY ONE SIDE of the wire's shield to ground.
Quote from: JustinFun on March 10, 2014, 10:26:47 AM
Not sure if this will solve my problem though, it feels like something is up with the grounding - when I'm using the Les Paul the buzz goes away if i touch the enclosure.
If your problem is only with les paul and doesn't get away even with touching the strings, you probably need to make sure that guitar's bridge is tighed to ground.
Quote from: sajy_ho on March 10, 2014, 11:10:11 AM
Yes exactly those wires, plus the one comming from input jack (green) and those two green wires connected to tone and volume. Don't forget to connect ONLY ONE SIDE of the wire's shield to ground.
Quote from: JustinFun on March 10, 2014, 10:26:47 AM
Not sure if this will solve my problem though, it feels like something is up with the grounding - when I'm using the Les Paul the buzz goes away if i touch the enclosure.
If your problem is only with les paul and doesn't get away even with touching the strings, you probably need to make sure that guitar's bridge is tighed to ground.
Thanks, will give that a try.
My Les Paul (a 90s Standard) emphatically does *not* have its bridge tied to ground - lots of gibsons from that period (and earlier) do not. It's not an issue on any other amp.
It looks good, is the chassis grounded? The chassis is a big sheild for the amp innnards. I use a jack that is grounded to the chassis. I have had smps whine when they arnt loaded down enough. The lt1054 hasnt been an issue like this so i dont know what tro say other than sheided wire from input to the first cap and sheilded wire from the cap and grid leak resistor ( 1m 2nd turret over ) to the tube socket. If your wires are running kinda funky they can pick up noise. Using a chopstick ( something non conductive ) to move them arouind while its on and whining helps. You have to be REALLY CAREFUL!! The voltages may not kill you but they cant be good for you so one hand in back pocket while chopsting so the shock doesnt make it across your chest cavity. Im not kidding it can F@#$ you up bad! I will see if I can get one to start whining. I suspect the chip though.
After looking at it some more, check your lead dressw and see if shortening up the wires to the tubes does it. They will pick up stuff being that close to eachother. sheilded wire helps but is not a replacement for good lead dress. I suck at it, i should know :icon_redface: sorry i havent been on much, doing a bathroom remodel in a hurry for a client. went from tubes to tubs overnight. dont like the change :icon_wink:
Just built this and it sound good. (http://i61.tinypic.com/a0gdnc.jpg). I wondering if it is possible to get this to push 1 watt? I read if you bypass the 380r resistor you would get more output and distortion but I don't need more distortion. My power is smps I can get up to a 190v but it starts sputtering so 100v max for me. Just wondering what I could do. Thanks
Hi,
this is a nice amplifier!
If you are using a higher voltage you need to change 380r to a lower value.
When you say bypass the 380r resistor you're talking about the bypass capacitor or you shorted the tube cathode to ground with a wire?
If you shorted the cathode to ground the sputtering could be a cause of current draw.
If you change the 380r to a lower value maybe it would work without the SMPS suffering from too much current draw.
I would start with 190r and see how it sounds.
Which SMPS are you using? Has the mosfet a heatsink? is the noise coming from the inductor? How big is the transistor? can it handle current enough to run the amp?
I would expect at least 25mA with a higher voltage. (two tubes in parallel)
Good luck!