Commercial Gainclone kit- building instructions

[joshuajoshua]

Originally posted by Peter Daniel
In a past I tried some larger transformers, but the effect wasn't that good and presently 400VA would be maximum I recommend for either stereo or dual mono version.

Thanks for the advice!

Joshua

[AndrewT]

Bi-amp your speakers.
Build a bass oriented chipamp for the bass driver.
Keep Peter's version for Mid/Treble.

Changing the transformer to bigger than 225VA for a single channel is unlikely to extend or lift the bass response.
Increasing the smoothing and the NFB cap is very likely to increase the extent of the bass comensurate with the increase in the input cap.

[joshuajoshua]

Originally posted by AndrewT
Bi-amp your speakers.
Build a bass oriented chipamp for the bass driver.
Keep Peter's version for Mid/Treble.

True, I thought about the bi-amp setup previously but to put (active) crossover before the amp is not my preference since somehow I feel it degrades the signal more.... ..

[/QUOTE]Changing the transformer to bigger than 225VA for a single channel is unlikely to extend or lift the bass response.
...... [/QUOTE]

Yeah, with my current setup I'm not sure how big the improvement would be.......

Joshua

[Peter Daniel]

Originally posted by joshuajoshua
True, I thought about the bi-amp setup previously but to put (active) crossover before the amp is not my preference since somehow I feel it degrades the signal more.... ..

What speakers are you using?

[joshuajoshua]

Originally posted by Peter Daniel


What speakers are you using?

I use 2 way setup : Fostex-87E and Eminence Alpha 15, all are arranged in open baffle.

Joshua

[Peter Daniel]

So I assume, there is some type of crossover in a speaker. You can easily replace it by passive filter components in each amp, no need to go active. And because those parts can be much smaller now, you could use better quality parts.

[joshuajoshua]

Originally posted by Peter Daniel
So I assume, there is some type of crossover in a speaker. You can easily replace it by passive filter components in each amp, no need to go active. And because those parts can be much smaller now, you could use better quality parts.

That is correct, I use 12db/octave crossover at the speaker.
I can try that passive crossover, which one do you think better, to incorporate that crossover at NOS DAC or at GC? Or just built them in separate box..?

Joshua

[Coreyk78]

Well for some reason I am still unable to start a new thread of my own. This isn't related to your kits Peter, but since I have already bought and built one of your kits I thought it might be ok, hehe.

I've built a LM3886 GC using BrianGTs boards and I have an extra set of boards and components that I would like to add to my amp to make a PA100 amp.

The reason I would like to do this is I have my eye on a pair of new Acculine A2 MTM configured speakers that have 4 ohm impedance and I thought this could be a good way to drive them without stressing the chips.

I've looked at national's schematic for the PA100, and to be honest I'm not that good at reading a schematic just yet. Would it be as simple as just adding a .1 ohm resistor at the speaker outputs of each board or am I missing something?

Any advice is greatly appreciated.

[AndrewT]

Originally posted by joshuajoshua


True, I thought about the bi-amp setup previously but to put (active) crossover before the amp is not my preference

No, Bi-amp your speakers.
Use one amp to drive the Bass half of the passive crossover, use a second amp to drive the Mid/Treble half of the passive crossover.

[Peter Daniel]

Originally posted by Coreyk78
I've looked at national's schematic for the PA100, and to be honest I'm not that good at reading a schematic just yet. Would it be as simple as just adding a .1 ohm resistor at the speaker outputs of each board or am I missing something?

I assume you want to use 2 LM3886 in parallel? Just follow 'red option' in this schematic: http://audiosector.com/lm4780%20amp.pdf