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Messages - lefizz

You need two speakers tripath amps are internally bridged so you cant bridge them yourself externally
Not sure fi this has been posted before sorry if it has.

Thats completly fixed the preamp,to little capacitance between the virtual ground and 0v, sound great and totally stable at any gain setting.
I am so happy!!

The 100 watt class-D really gives this setup a hell of a kick. Utterly deafening in a flat, my neighbours must be getting a little annoyed. Thanks for all the input guys, even though this thread has turned into a bit of a monologue of late.
The Newcomer's Forum / Re: A general power supply?
November 02, 2007, 06:47:20 PM
In DIY audio many people also sound they say great. I know many cases where people have used them for LM3886 and clss-D kits after using traditional transformer setups and got an improvemnt in performance. I have used them with some of the Tripath kits and they do seem to sound better than the traditional toroid/ diode setups.

The main advantage is that you can boost rather than just cut frequencies. This means a wider range of tones can be produced by the preamp, i cant think of any disadvantages.
My amp is still pumping at high gain levels. Could this be because i haven't got enough capacitance on the preamp board? i have eliminated the speakers, tried a hifi one and got the same effect, replaced the 25watts class-t with a 100 watt board. And removed the mixer amp temporarily. The only thing the same as the first test is the preamp so i guess this is where the issue originates. At the moment the virtual ground is only decoupled with 1uf and the 25v to gnd with 10uf? I think i might put some decent 100uf in both locactions to see what happens.
The boards from this site look very interesting and not difficult very difficult to implement.
I change input settign resistor int he second stage (r15) from 1m to 50k. This seems to have clear the sound up a lot, more test to follow tonight.
Well i guess that you get tone control on your amp??

And an active one will allow you to shape the sound more however i think that this cicuit as it stand doesnt give enough gain
Then i was thinking but this would mean that the second 11 x section from the initial design would be removed so i imagine i would have to stick this back on after the active tone. Does that make sense?
Right i was reading a section over on DIYaudio when a guy called minion posted an active tone control section. I thought this combined with the 2 stage preamp i was working on would probably work quite well.

This was my first thoughts on the idea
Preamps and Effects / Motor Boating?
October 30, 2007, 06:35:39 AM
My amp setup uses a 100 watt class T amp and the TL071 based preamp many people here have help me with.

The issue is this, at high gain setting, i.e. when i want to play loud, the amp ocassionally gets stuck it a sort of weird feedback loop with the Bass driver pumping in and out slowly with no input from the guitar. Is that called motor-boating? Even totally dampening the strings doesnt stop it, the only way to control is it to either turn of the amp or cut the volume right down for a moment.

I was wondering what causes this and what could be done to reduce/eliminate it.

Any feedback(no pun intented!) greatfully recieved.

LJ King, i found that a couple of the pot were broken, replacing them fixed the issue, thanks a lot.

Well it is defientely connected, however i did have to bend some of the pins on the pot back into place after bending them 90 degrees back to wire point to point. This is probably the issue, i will check it out tonight.

Thanks a lot.

Oh also i set the input impedance of the first section to 1m, the second section is set the same. I imagine this isnt needed since the issue with the guitar pick has already been dealt with. What would a suitable value be for the second input impedance settign resistor? 100k?

Hello all,

I have been workign on my preamp again this weekend with less than stella results.
I wanted to change the setup so i had a fixed gain of 2 in the first section, then a volume pot and tone tones between it and the final fixed 11 x gain section. To this end i took the schematic from 'Tone stack generator' software and built this with a pot on the front for gain control.

I put this back in and the only thign that works is the volume/gain control none of the tone controls are doing anything.

Any ideas?