Burning Amps

[Magura]

I've read the articles but never done any matching. I would think that you *must* use a socket of some sort to put each DUT into the test rig, or you risk shorting it out (or the test rig) with alligator clips. Anybody done this either way?

- Eric

Sockets are ok if you need to match 25 parts, but too much trouble if you have hundreds. Isolated alligator clips does the trick.


Magura

 

[Eric Weitzman]

Thanks for the pics, steenoe.

Magura, wouldn't it be faster & easier to just plug 'em in a socket than hook up three clips?

- Eric

 

[Magura]

Thanks for the pics, steenoe.

Magura, wouldn't it be faster & easier to just plug 'em in a socket than hook up three clips?

- Eric

Depends how you intend to do it. If done like I described earlier, 3 clips are the easy way.


Magura

 

[Eric Weitzman]

Magura,

Do I get this right, then? You'd clamp 100 transistors between two bars and run down the line, moving the clips from one to the next?

- Eric

 

[Nelson Pass]

Nelson Pass: " ... BA #1 will launch as soon as DIYAudio is ready to post it, probably in about 10 days. ..." Got advance pictures??

Surely one of the recipients has a camera. The finished product looks
just like those.

 

[Nelson Pass]

Do I get this right, then? You'd clamp 100 transistors between two bars and run down the line, moving the clips from one to the next?

You are far overestimating the effort involved. It's really not that
critical unless you are planning something special, like no
ballast resistors at all.

And even then......

 

[Variac]

Rear view of finished Single-ended Burning Amp
30 WPC

Sounds like a dream....

 

[PSz.]

Quick cell pic of the guts.

 

[FastEddy]

I also have one of the amp chassis (#28) ... Sorry, I misunderstood and assumed you were using a completely new design = "look and feel".

Are we going to be able to buy the chassis separately? Its a great idea / concept = straight forward and completely adjustable, very versatile ... good looking too! =

 

[PSz.]

I was just looking over my BA chassis, and realized that it has IRF240s on one side with 1.0R source resistors and IRF244s on the other side with 1.8R source resistors. Probably not a huge deal, but if anyone else took home a similarly equipped chassis I would be interested in trading one side. I would prefer both sides of my amp to be identical.

Nelson, I am quite excited to see what you have designed for the lucky few who got to bring these chassis home. I was starting to worry that this thread had gone dormant and began thinking about stuffing an F series amp into mine.

best regards,
psz.

 

[Variac]

Sorry, I misunderstood and assumed you were using a completely new design

Aw, we was jist funnin' you

 

[Nelson Pass]

I was just looking over my BA chassis, and realized that it has IRF240s on one side with 1.0R source resistors and IRF244s on the other side with 1.8R source resistors. Probably not a huge deal, but if anyone else took home a similarly equipped chassis I would be interested in trading one side. I would prefer both sides of my amp to be identical.

If you can't find a swap, then put the 244's on top (ot bottom) of both
sides, that way you'll have the symmetry that allows audiophiles to
sleep at night.

From a performance standpoint, they are identical, but the 240's have
fatter pins.

If you are building BA1 you will want to keep the 1 ohm and dump the
1.8 ohm resistors.

 

[PSz.]

Thanks for the reply Nelson. I am actually one of those with complementary output stages awaiting "a similar but different design." So swapping the devices around wont help, but if the performance is identical then I will try not to fret about it.

I do have serious symmetry issues.

I will definitely be checking all the existing parts values when I build this beast up. Still trying to decide what would be the best amp to build for my speakers. A big transconductance amp is what the big JBL woofers seem to be asking for.

The upcoming Firstwatt F6 and B4 have me on the edge of my seat already. Now the BA series is going to induce insomnia, and I will enjoy every moment of it.

best regards,
psz.

 

[Variac]

A big transconductance amp

It really seems that there would be a use for a powerful transconductance amp- with an active crossover I think I have mentioned this before somewhere..

I suppose the advantages would be better low response and maybe more control of the cone in all frequencies. I think it would affect MY 15" JBL woofers positively because they are highly damped..

I also suppose that one doesn't get the low response for free- it must take lots of power? more? less? better ? worse? - than equalization.

Even if the power required is similar to EQ requirements, perhaps the entire bass quality is improved. Anyone?

Mark

 

[Nelson Pass]

A powerful transconductance amp would be easy to do.

 

[PSz.]

Build one I would.

 

[Andersonix]

Please forgive me for I know not quite what I'm asking for.

Can BA1 be optimized to drive the ESL panels on my ML SL3? (4 ohm nominally, passive 250Hz 12dB/oct high-pass xo begins with a 30uF cap and 1 ohm resistor, has a LCR notch filter and LR in parallel, then to the transformer.) I have a huge encapsulated Threshold-labeled Bando transformer (>800VA? two secondaries 114VCT and 31.6VCT when wired for 120VAC, Thanks Nelson!) that just fits inside my shorter BA chassis.

 

[Nelson Pass]

The single-ended nature of the output stage will cause lower power
when the impedance dips. BA2 is probably a better candidate with
push-pull operation.

 

[Nelson Pass]

Build one I would.

And so you shall.

 

[Variac]

Does this idea that the transconductance amp would have advantages as a bass driver seem reasonable? I guess you would have said something otherwise-especially as you probably have F1's and F2's laying around to try...