amp recommendation

Lico · 23rd March 2010, 10:54 PM

I would like to try building a new amp. The son of zen and related designs look very interesting, but since I've never built anything like it I haven't the slightest idea how to start messing with the schematics.

I've done a tube amp that I love and a chip amp that sucked. However, the chip amp required a pretty expensive power transformer that I would like to reuse if possible. It is 225VA, 2x24v. Does anybody have a design that would work well with this power?

I don't have any speakers for it yet, but I will be using full range drivers in a small-ish package (sealed maybe?)

Lico

Bill Fuss · 24th March 2010, 01:12 AM

If you are dead set on reusing that trafo then you will have to find an AB class amp of around 60watts/ch. The Pass forum is pretty much geared towards class A operation which generally uses much larger power supplies with lower rail voltages. You should pose the same question on the Solid State forum where you should get many proposals and suggestions. There's plenty of good sounding AB amps out there.

Best, Bill

juma · 24th March 2010, 10:23 AM

Quote:

Originally Posted by Lico

... power transformer that I would like to reuse if possible. It is 225VA, 2x24v. ...

SymAsym5 - Project

Search in Solid State section of the forum, there are numerous threads about this amp.

Bigun · 25th March 2010, 04:52 PM

If you want to build a design by Nelson then I don't see why the trafo you have can't be pressed into use. You can build a Class A amplifier with this trafo.

I'm not familiar enough with Nelson's amplifiers to suggest the 'best' one for you, but I would suggest that you choose one with an available pcb (again, not sure of what's available)

One option for a simple amplifier is Zen4, it recommends a 300VA trafo, but if you can accept a more limited headroom and lower bias current you could at least start with your 225VA.
http://www.passdiy.com/pdf/zen-v4.pdf

Or look at one of the Aleph's.

EUVL · 25th March 2010, 05:05 PM

225VA 2x24V will do ONE channel of F5 if you add a regulated power supply as per Zen Version 3.
Too much voltage and too little current for 2 channels I am afraid.

If a 225VA transformer is expensive for you, then maybe you should find something else other than Class A.
This is certainly not the only costly item and most likely not the most costly item.

Patrick

Bigun · 26th March 2010, 02:10 AM

this thread is so disappointing... where is the DIY spirit, can people only build things exactly as an original, nobody with any vision here as to how to make something with a given trafo ?

perhaps the Solid State forum would be a better choice afterall.

Bill Fuss · 26th March 2010, 02:48 AM

It has nothing to do with the DIY spirit. It has everything to do with basic math.

34V rails with an 8ohm speaker requires 4.5 Amps per channel. x 2 x 68v total = over 600 va

DougL · 26th March 2010, 04:32 AM

I agree with Bill.
If it was a 600 VA transformer, I would suggest a regulator to lower the rails to 24V and build an F5. But 225 VA is really not enough, especially if you burn some off in the regulator. And Choke input would help, but spending $50 to use a $30 transformer seems a bit silly. On the other hand, we are silly types hereabouts!

Doug

juma · 26th March 2010, 11:20 AM

With that transformer (2x24V, 225VA) two channels of F2 could be built with somewhat lower bias - one channel per secondary. Some regulation can be added to lower the voltage to +24V (CRC or active, F3 style).
It's simple, it's class A ...

First Watt: Downloads

Bigun · 26th March 2010, 04:30 PM

That's more like it !!!

23rd March 2010, 10:54 PM	#1
Lico diyAudio Member Join Date: Oct 2003 Location: New Jersey	amp recommendation I would like to try building a new amp. The son of zen and related designs look very interesting, but since I've never built anything like it I haven't the slightest idea how to start messing with the schematics. I've done a tube amp that I love and a chip amp that sucked. However, the chip amp required a pretty expensive power transformer that I would like to reuse if possible. It is 225VA, 2x24v. Does anybody have a design that would work well with this power? I don't have any speakers for it yet, but I will be using full range drivers in a small-ish package (sealed maybe?) Lico

25th March 2010, 04:52 PM	#4
Bigun diyAudio Member Join Date: Jan 2009 Location: K-W Ontario Blog Entries: 2	If you want to build a design by Nelson then I don't see why the trafo you have can't be pressed into use. You can build a Class A amplifier with this trafo. I'm not familiar enough with Nelson's amplifiers to suggest the 'best' one for you, but I would suggest that you choose one with an available pcb (again, not sure of what's available) One option for a simple amplifier is Zen4, it recommends a 300VA trafo, but if you can accept a more limited headroom and lower bias current you could at least start with your 225VA. http://www.passdiy.com/pdf/zen-v4.pdf Or look at one of the Aleph's. __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

26th March 2010, 02:10 AM	#6
Bigun diyAudio Member Join Date: Jan 2009 Location: K-W Ontario Blog Entries: 2	this thread is so disappointing... where is the DIY spirit, can people only build things exactly as an original, nobody with any vision here as to how to make something with a given trafo ? perhaps the Solid State forum would be a better choice afterall. __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

26th March 2010, 04:32 AM	#8
DougL diyAudio Member Join Date: Feb 2004 Location: Wheaton IL. Blog Entries: 25	I agree with Bill. If it was a 600 VA transformer, I would suggest a regulator to lower the rails to 24V and build an F5. But 225 VA is really not enough, especially if you burn some off in the regulator. And Choke input would help, but spending $50 to use a $30 transformer seems a bit silly. On the other hand, we are silly types hereabouts! Doug __________________ Scienta sine ars nihil est - Science without Art is nothing. (Implies the converse as well) Mater tua criceta fuit, et pater tuo redoluit bacarum sambucus

26th March 2010, 04:30 PM	#10
Bigun diyAudio Member Join Date: Jan 2009 Location: K-W Ontario Blog Entries: 2	That's more like it !!! __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.


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24th March 2010, 01:12 AM	#2
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	If you are dead set on reusing that trafo then you will have to find an AB class amp of around 60watts/ch. The Pass forum is pretty much geared towards class A operation which generally uses much larger power supplies with lower rail voltages. You should pose the same question on the Solid State forum where you should get many proposals and suggestions. There's plenty of good sounding AB amps out there. Best, Bill

25th March 2010, 05:05 PM	#5
EUVL diyAudio Member Join Date: Oct 2003	225VA 2x24V will do ONE channel of F5 if you add a regulated power supply as per Zen Version 3. Too much voltage and too little current for 2 channels I am afraid. If a 225VA transformer is expensive for you, then maybe you should find something else other than Class A. This is certainly not the only costly item and most likely not the most costly item. Patrick

26th March 2010, 02:48 AM	#7
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	It has nothing to do with the DIY spirit. It has everything to do with basic math. 34V rails with an 8ohm speaker requires 4.5 Amps per channel. x 2 x 68v total = over 600 va

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