The Brymus amp

sean k · October 16, 2009, 04:53:15 PM

The man asked so I've done it and I've done these two, the others the okko, simply because it's been raining quite a bit and I had some spare time. So please don't see me as the man who does free plans because they do actually take quite a bit of time and thats something I can hardly find for myself... if I want to rest here and there.

That said I am open to swaps if people want project plans and I'm even kinda hopin' that Brymus and Caspercody are goin to offer to send a few bits and peices accross the seas to the southern hemisphere.

God, I hope they are right!

Bubesz · October 17, 2009, 04:00:50 AM

Oooh... If you post this just 2 days earlier, I could use this layout

I designed my own board and etched it 2 days ago... And I think you have more experience in designing boards than me

Do you think this works OK? http://img86.imageshack.us/i/kp070.jpg/
This is the second version of the preamp, with one-pot tone control. http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/386PreAmp_2.jpg This one.
Oh, and imagine more space between signal path and feedback loop.

sean k · October 17, 2009, 03:11:52 PM

Hey Bubesz, I think I may have blundered as I've done the original, rev 1, preamp with the febder style tonestack and not rev2 which has the muff style TS. I find it helps if you do the drawings as close to scale as possible so that the intertwinings work out right when you come to working on copper but if it works for you then it works. I couldn't get a size on your drawing that made it easy for me to follow, it was either too small or too big... having the drawing about 800 x 600 makes them easier to follow.

I have done alot of arty stuff in my life so I'm fairly good at drafting but that doesn't mean I'm any good at electronics... It's still 98% mystery to me so don't count my skill with a pencil as a prerequisite to my success. I just have nice looking failures

Brymus · October 17, 2009, 07:30:58 PM

Hey thanks Sean !
Yeah it was the latest version with the Marshall tonestack I was hoping for.
That looks good ,like I said layouts arent easy for me I breadboard it then use perf and Bubz wanted a PCB.
I have been using the latest pre-amp http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/PreAmpAsPedal.jpg
As a pedal in front of my amps and it works for so many sounds from clean and bright to dark and hard.
I just ordered from Tayda when it gets here I will send you some ICs,I ordered TDA2009 for next amp with this preamp.
If you like I will get some more TDA1519B from Apex Jr and send you one of those instead.But I will send you all 3 ICs so you can build one since you drew the PCB layout.

I know it may look like a TS and a Big Daddy with a Marshall stack inbetween but thats not how it came to be.
I only lifted the FET stage from the Big Daddy (thanks again ROG)
The tonestack is from a tube amp I built.And the rest came from the data sheets.
I did try the Smash Drive when I noticed how similiar they were and tried moving various tonestacks in front of the 386 like the Smash Drive.
But in the end this is what I thought sounded the best,What I didnt draw(forgot) was a 47uf bypass on pin 7 of the 386 and the 25k pot in series with the 2x 1N34a diodes to ground.
Oh and I also added a 100K pot in series with the 1M pot on the OD channel this way I set the 100K pot to "just breaking up" then turn the 1M pot up or down to make the "heavy" sounds.
I plan on adding a rotary switch with different diode options but these are all pretty standard op amp clipper mods.

sean k · October 19, 2009, 02:09:00 AM

If you want to send me some 1519B's that'd be great and I'll send you the original dawing and also do a scaled version for pcb printing. I'd most probably do it 2/1 so it could be scaled down and get finer. I'll put my address in a message and you give me yours. Cool, I'm glad your happy.

Thomeeque · October 19, 2009, 04:56:20 AM

Quote from: Brymus on October 17, 2009, 07:30:58 PM
...
I have been using the latest pre-amp http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/PreAmpAsPedal.jpg
...

Hi! May I just ask what is a purpose of the U1B stage here? Does the U1A stage have to buffered? Thanks, T.

sean k · October 19, 2009, 04:39:56 PM

No body noticed that I missed the source to ground resistor on the first stage. I did when I started on the new drawings. Oops

Brymus · October 19, 2009, 07:45:25 PM

Quote from: Thomeeque on October 19, 2009, 04:56:20 AM
Quote from: Brymus on October 17, 2009, 07:30:58 PM
...
I have been using the latest pre-amp http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/PreAmpAsPedal.jpg
...

Hi! May I just ask what is a purpose of the U1B stage here? Does the U1A stage have to buffered? Thanks, T.

The idea was to feed the tonestack from a voltage follower,I think it improves the sound but no way of proving it.
And it also seems to make the diodes to ground clip better,again not sure but after much trial and error this is what sounded best to me.

sean k · October 23, 2009, 03:57:18 AM

Bubesz · October 23, 2009, 04:09:54 PM

I successfully built the preamp

There are still a few problems with it, it has a loud hiss, the gain controls behave a bit strange (you get a LOT of change with a little modification, then nothing for a while, then big change again) and... the clean channel is not really clean and has an octave-like effect

Apart from that, this preamp is great, it has SO fat sound.

Any suggestions to improve it?

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The Brymus amp