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The "$250" Amp? - 6LU8 Compactron SE, UL

I am working on possible designs,

One question I have for the people who might know,

What is a good simple pre-amp design to go with the compactron?

I plan to run a CD mostly and end up allowing my daughter to use it for her room.

Which is why I want to build the compactron with a simple pre, so it would work for her, she is cd only.

thanks.
 
Just put a volume pot on it and if you want, two sets of RCA inputs with a toggle switch. Don't really need a pre if it is for a BR set......depending on your speakers I guess..
 
Right now I have infinity SL-30's (92 dbl@1 watt, 1meter; 6ohm) and B&W DM570's (91 dbl@1 watt, 1meter; 8ohm) as candidates for her room, so it won't need a preamp in this case?
 
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You won't need a preamp if you have something to adjust the volume. I just used the output level adjustment on the source.
 
Thanks, I am learning and the compactron is going to be the vehicle I try to learn on.

I probably would need a volume control pot cause the cd player she has has no such ability.

If I wanted to add a volume control pot to the design, where would I put it?

Near R9 position or R10 position?
 
Hey all,

I'm joining you gentlemen in the build.

Ordered two of the Antec power toroids. Planning to build mono-blocks.

Looking forward to the project! Now to get some OPTs ordered and other various parts.

Thanks everyone!
 
These Antec toroids are huge!

Seems like a lot of power supply for the money.

Itching to get these started.
 
So in UL we are looking at around 5wpc?

Are there any here that actually prefer solid state rectification?
 
rage said:
So in UL we are looking at around 5wpc?

Are there any here that actually prefer solid state rectification?
Click to expand...

I do, in a way. I come from the guitar amp side of things and tube rectification is desired by many over there because of the pleasing compression-like tendencies of tube rectification. But for hi-fi reproduction, I feel like that any compression or sag would be detrimental. Of course, the design of the amp/power supply comes into play here. I do have to say that I have not noticed any sag with this 6LU8 amp. But I don't push it wide open either.
 
Hey Goya, how would you explain the sonic qualities of sag or compression??? I've heard the terms forever but don't really know how those two things sound. Cheers.
 
I'm thinking of making my mono-block chassis out of diamond plate. Mount the outputs beneath and the toroid + compactron tube up top.

This gives me kind of a cool industrial look plus only one tube, but it kind of makes me run with SS rectification. I'd like to try it, worst case I get to try a tube rectifier later for comparison.

My Fisher 400 uses a silicone bridge, and at least one other amp I am familiar with (and like the sound of) is also SS rectifier.

Will the schematic of the power supply change much going that route?
 
where you running the compactron with your tweeters during the smac meet?

I split early and missed your presentation unfortunately, but your system sounded (and looked) great!
 
djnagle said:
Hey Goya, how would you explain the sonic qualities of sag or compression??? I've heard the terms forever but don't really know how those two things sound. Cheers.
Click to expand...

I have been toying with the idea of posting a thread with links to 24/96 wav files uncompressed and compressed for just such a demonstration. It's better to hear it for yourself than to read a description. And what I mean here is the use of a studio compressor as opposed to raw recorded tracks. There are several folks here that are musicians and record their own music but most here are likely unfamiliar with the difference.

But for sag, the term usually applied to instrument amps, it simply means that when the amp is hit hard with a transient, or even a loud sustained signal, the power supply "sags" under the workload. Dynamics are lost and the whole amplified signal sounds weighed down. (for lack of a better phrase) The best way to hear it is to turn an amp up loud and hit a hard, full power chord on a guitar and let it sustain. As the chord starts to ring softer and lowers to a certain threshhold, you can hear the "life" come back into the amp. It's really just a harsh form of compression. And again, it's easier to hear it for yourself than to read a description.

Edit for a little more clarity: Of course, the overdriven power tubes play a part in this effect as well. And when I mention the chord becoming quieter until it reaches a threshhold, it may be quieter acoustically, but the amplified signal is still as loud as the amp can be until it reaches that threshhold. This, in effect, is what a compressor/limiter does. It will smooth out the peaks in the signal.
 
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(Thanks for helping Goya)
Also different rectifiers have more sag then others. (high resistance/voltage drop)

For the purposes here and the amount of current drawn plus being class a se amp
your not going to get any sag and or compression based around this power supply.
 
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