Thanx Teemuk, great info.  :tu:

Quote from: Enzo on October 18, 2008, 02:30:12 AM
Pull the chassis.  There will be a pair of main filter caps standing near the center of the board, if I recall the layout.  Dismount the board flip it over and resolder them.  I'd bet my lunch money that is your problem.

After restirong hte board to poistion, run a large glob of silicone sealer or hot melt between them to glue them together into one mass.  Also run a bead around the base of each.  Those measures will help prevent them shaking around and cracking their solder in the future.

And for the record, that would be 120Hz hum in this case.

Good advise from Enzo , that is the best place to strat ,since your allready in there check all the other solder joints and clean all input and outputs(1/4 " jacks) and do all the general inspection stuff , a small hum is common in most amps, but this amp is usually pretty quiet. Good Luck


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Generally the higher the impedance the better the sound quality. It all depends on how many speaks your going to use and how you plan on wiring them in(parallel or series) myself I usually buy the 8 ohm speaks , they are easier for me to cofigure.

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Quote from: Number_47 on October 15, 2008, 12:59:56 AM
So I've just gotten a hold of a Peavey Supreme XL head. I also have a Carvin SX300-H head, both amps are S.S. I've placed them side by side and done a comparison, and to my ears the Carvin sounds more "tube-y" than the Peavey does. Why is that?...is there some magic involved?..or does it really just boil down to the resistors, capacitors, transformers used? I've played through them both out of a 2x12 Avatar speaker cabinet, along with & without a fuzz pedal on my Fender Standard Strat...sorry for the stoopid questions but i have to know! Also if it IS just a matter of different components is there any way to make the Peavey sound like the Carvin? maybe by switching out parts?....any advice would be greatly appreciated

Thanx!

Eddie Hendrixx

First they are total different circuits ,no the peavey cannot be made to sound like the Carvin(not simply anyway). The Carvin was built to sound tubish , the Peavey was not. Finally , If you want to do a real taste test of these to amps , I would recommend using the speaker cabs that are designed for them(different speakers change the tone of any amp).

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Great info Teemuk, but if your amp is a peavey , and you are wanting to replace with a speaker that is not peavey , I recommend a 75 Watt. Peavey amps are rated at RMS(average output, a old standard) however , most new amps are rated at peak values(speakers as well)

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I would lean towards the 50 Watt because of price.

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A lttle more info is needed bro, is this a solid state amp or tube , does it hum with the cord not pluged in , is it a loud hum or does the hum change pitch, is your wall outlet grounded? some amps have a slight hum to them this is called the amps breath.

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The Texas Heat is a good speaker ,however 150 Watts is a bit more than a 18 watt amp needs , I can't see it breaking up well. Try the Jensen Mod or the Celestion
vintage 30 both great speakers.

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All I can add to Teemuks great list, is check out Gerald Webers books(mostly about tube amps but tons of info on tone) , and Check out musiciansfriend.com last time I looked there where a few books there , good luck in your designs bro.

                                           
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Quote from: Marek on September 30, 2008, 05:07:11 AM
I'm looking for a good SS parallel loop schematic. I want to plug in a DSP effect just before a power amp input and to be able to mix the effect with the original signal. I could only find Marshall schematic but I've seen bad opinions about this loop (I'm not sure whether they are justified). Any ideas?

Mark

What Teemuk says is perfectly correct however let me understand what your after , do you what a wet dry mix between your effects from a effects lloop? If so do you have a dual channel or a single channel amp(see where I am going with this)?

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Teemuk is dead on bro, I would say the high impedance is your problem.

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It's a bad pot , if you can half #$% solder it's pretty hard to incorrectly solder in a pot.

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I have not built this amp myself( not enough time) however , I will say all of armstrom's suggestions are a good start , however , looking at the diagram of this little amp , I would think it would a small amount of hiss , I would start with changing the 100uf cap (which is recommended on the web page) also I would increase the supply voltage to 12 volts as recommended ( more headroom less hiss).
Also the FET sometimes you get a noisy one , the 386 what can ya say maybe , but I doubt it. there's just not a lot that can go wrong with this little amp. Good Luck

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Shield may grounded wherever it is easiest for you , keep leads as short as possible, watch lead dress, and try not to cross supply lines with signal lines if possible. AS far as 1/4 input jacks go I use 2 conductor shielded and unshielded , in most cases it is rather unimportant.

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Try the Roland Micro Cube , it has Chorus , Flange ,Phase Tremelo Delay and Reverb built in and work fairly well , it also has 6 amp models that are ok . This little amp is AC or DC powered and sound pretty good , and cost $125 retail.

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