Complementary zen (zenv5)

[gregjpeters]

Hello diyers,

I wish to build a class A amp, and do not wish to buy/make PCBs. So I am contemplating making the Complementary Zen (zen v5), which can easily be point to point wired. Now the question:

I have 6 ohm speakers which I do not wish to replace. How well will this amp work with 6 ohm speakers? Will I need to lower the output impedence? How can I do this? Can I parallel output devices? How (details please)? Or do I really have to bridge two amplifiers?

Looking at the schematic included with this post, it seems I can easily parallel more output devices. However, I'm not sure which parts of the circuit need to be "doubled". I guessing I need to add another set of R9 & R10 and R11 & R12, but what else? It also seems I could get more power this way. What do you think. I'm pretty new to this so require answers in english not ampish

Your help is most appreciated.

Cheers.


The pic was removed. This is a link to the Complementary Zen article at the PassDIY site. See Figure 3.

[BobEllis]

You should also "double up" R7 and R8 - these prevent oscillation and should be as close to the gate of each FET as possible.

[ingvar ahlberg]

I think the Zen v5 is sufficient for 6 ohm load as it is, but if You want to add output devices the "doubbling" of mentioned resistors R7-12 is right, should be close tollerances (matched).
If You change Yor mind about PCB this layout works good:
Note that R numbers are not consistent with schematic, but easy enogh to see what´s what. R1 equals R9+R10

[gregjpeters]

Thanks for the replies. Just wondering:

1. Do I need to halve R5 and R6 to provide more current to feed the additional fet gates?

2. So, does "doubling up" on the output devices halve the output impedence (and double the power if rail voltage and bias is the same - per device, but doubled in total, right)?

3. I assume I will need twice the power supply as well, assuming I use the same rail voltages and bias per device (but total bias current would be near 4 amps, or double original value). Seems it would be good to lower the rail voltage with the same bias value (per mosfet) to reduce the power dissipation of each device while still maintaining a decent output.

4. How do these amps sound anyway? Pretty good? (Just been reading about the DOZ amp, and heard some harsh words about them).


Thanks alot guys. Most helpful. Will post my proposed schematic in my next post.

[gregjpeters]

Will this work?

What overall value do I need for the power resistors? NP suggested 0.1 - 0.5 ohms in his original article. What do I need here?

[BobEllis]

Originally posted by gregjpeters
Will this work?

Only if your FETS are perfectly matched. Instead. connect 2 source resistors to each device's source pin, with no connection between the source pins. This will reduce the effects of transistor mismatching, but they still ought to be closely matched in pairs (IRFP240 to IRFP240, etc.)

You could use higher value source resistors for even better mismatch protection. Four parallel 1 ohm resistors gives you roughly the same resistance as the original.

[ingvar ahlberg]

That wont work, You have to use separate source resistor for each transistor as Bob says. Paralleling output devices has nothing to do with output power, thats purely a product of rail voltage divided by load, You can connect any number of transistors in parallel, +/- 35V rails still produce the same output power but with lower output impedance and of course a lighter dissipation task on each transistor.

[Nelson Pass]

Say guys, I just finished *****ing about DIYZONE posting
exactly the same schematics without permission.

I officially give you this permission here and now, but I think
we need to consider how this is to be done in the future,
otherwise other sites can point to DIYAudio as an example
of why it's OK.

[Sandy H.]

For reference, in the following, I only linked to a picture of a pile of stuff in my garage, but this could be substituted for copyrighted info as well. But, at this time, I hereby release the image of my messy garage to the public domain. . .)

The typically accepted, most honest way of doing this is to post a link to the source site directly, correct?

Such as:

http://www.tshouston.net/shop/spares2.jpg

instead of using the IMG tag (unless it is an embedded picture of your own without copyright from your own site to save on DIYAudio's bandwidth), such as:

.

Is it typically proper to alias the link such as:

Pile of junk

or is this also in bad taste, even though it goes to the source site?

Questioning the proper etiquette.

Best Regards to all,

Sandy.

*edit: Resized the picture to reduce wasted bandwidth. Sorry.

[Michael Rothacher]

IMHO

The method which most appropriately denotes the source of your reference and drives traffic to the intended site accordingly is:

See Nelson Pass Complimentary Zen Amp

Many websites have very specific policies about linking to their material and PassDIY may need to adopt same.