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Old 14th January 2006, 10:16 PM   #1
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Default Balanced Zen V4 Questions

I am in the process building a pair of Zen V4 monoblocks. I have previously built BoSoZ preamp and paralleled Return of Zen biamped monoblocks with outboard power supplies. (These projects are posted on Pass Lab’s DIY Gallery http://www.passdiy.com/gallery/zen-p5.htm .) I am not a EE and hope to borrow some insight from this forum. I have the following questions, and I solicit opinions:

• Should I build these monblocks balanced or parallel single-ended? I am leaning to balanced, as my preamp is balanced and Nelson’s articles hint that it sounds better that way. My speakers "Homebrew" Focal Daline MTM transmission line tower speakers. These are similiar to JMLabs' Daline 6.1 using two Focal 6V415 midbass’s and one Focal TC-90tdx tweeter, and supposed to be 8 ohm nominal.

• If balanced, I assume that the +input corresponds to the –output. Is my assumption correct?

• If balanced, should I eliminate the output capacitors, C1 and C4?

• If balanced, I assume that voltage regulating Q5 should be doubled up, with their outputs connected, and MOSFETs should be matched in order to even out the current flow and heat dissipation between the MOSFETs. Is my assumption correct?

• If balanced, I assume that transistors for the + and – should be matched. What is the order of importance of closeness of matching (e.g. is Q1 most important)?

• If my set of monoblocks require 12 IRFP044’s, is the purchase of 20 sufficient to get enough matched pairs?

• I am going to wire my circuitry point-to-point. Should I use sheets of 1/16” Teflon (not very rigid and foam like) or fiberglass perf board? I tried the Teflon on a set of Aleph 2, but I never got the amps to work and never could find an error in my wiring. I am worried the Teflon is not a good enough insulator.

I have already completed the following:

• Each monoblock’s chassis is composed of 6, 5.25” sections of what seems to AAVID #61570 heatsinks (surplus from MECI 3 years ago, 0.60 degC/W) connected by 1/8” thick aluminum angle. These sinks form the 4 sides, with 2 sides being 2 sinks wide and the other 2 sides being 1 sink wide. The exterior size of each chassis is 20”x13” (including fins) by 6” tall.

• Power supplies for both channels are outboard in single aluminum box attached to the amps via an umbilicals composed of four 12-gauge solid copper conductors with a Neutrik 3-connection Powercon connector (+47V, +47V, & signal ground) and a 4th conductor for the chassis ground. The aluminum box is constructed of 1/8” thick aluminum sheet and 1/8” thick aluminum angle. Power supply is composed of a single Plitron 1000VA, 35+35V transformer with a Pi filter (2 - 68,000uF caps, with a 2.5mH inductors per channel). There is also 20A EMI filter between the 20amp IEC chassis connector and the transformer. This filter can be switched in or out via a DPDT on/off power switch.
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Old 15th January 2006, 08:36 PM   #2
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I have an additional question:

* With an unregulated supply voltage of 47-48 volts, should I have the Z1-5 zener diode stack?
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Old 16th January 2006, 02:48 AM   #3
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Default Going Balanced?

If you're going balanced in monoblock form, what you're basically doing is building 4 single ended amps. Are you building from the PCB you can buy direct from Passlabs? If so, you'll need 4 boards (2 for each balanced channel).

http://www.geocities.com/lelamjade/ZEN4.html

Those are my twin Zen v4 that I built 2 or 3 years ago. It's currently my main ss amp and I do use the Balanced Line Stage preamp to drive it.

In both monoblocs, none of the capacitors were omitted. Actually I can't remember altering any parts on the PCB as i've set the amp up to run either 4 channel single ended or 2 channel bridge.

If you search the posts, many have had troubles getting the Zen v4 running right. I was lucky to have zero problems. Perhaps it could be that all my components were matched. Fets, caps, and even the resistors were matched. Note that you only have to match per monobloc. So out of the 20 IRFP044 you buy, you only need to have a quad set matched, the other 2 IRFP044 don't have to be matched as they are for voltage regulation (if my memory serves me right). Again, depends on how picky you are.

BQ
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Old 16th January 2006, 04:48 PM   #4
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Default Re: Going Balanced?

Quote:
Originally posted by Super_BQ
If you're going balanced in monoblock form, what you're basically doing is building 4 single ended amps. Are you building from the PCB you can buy direct from Passlabs? If so, you'll need 4 boards (2 for each balanced channel).

http://www.geocities.com/lelamjade/ZEN4.html

Those are my twin Zen v4 that I built 2 or 3 years ago. It's currently my main ss amp and I do use the Balanced Line Stage preamp to drive it.

In both monoblocs, none of the capacitors were omitted. Actually I can't remember altering any parts on the PCB as i've set the amp up to run either 4 channel single ended or 2 channel bridge.

If you search the posts, many have had troubles getting the Zen v4 running right. I was lucky to have zero problems. Perhaps it could be that all my components were matched. Fets, caps, and even the resistors were matched. Note that you only have to match per monobloc. So out of the 20 IRFP044 you buy, you only need to have a quad set matched, the other 2 IRFP044 don't have to be matched as they are for voltage regulation (if my memory serves me right). Again, depends on how picky you are.

BQ
Super_BQ nice Amps!

I am lean towards balanced, and if I go that way I will probably exclude the output capacitors. Also I am going to wire point-to-point, enabling each MOSFET to be on its own heatsink (which should be more efficient in dissapating the heat). Your heatsink look similar to mine, except yours must be about 8" sections, while mine are 5.25" sections. It sounds like your amps can be switched between balanced and bi-amped single-ended, and thus need the output caps for SE.

I have not read about the problems with the Zen V4. Are the problems with the amps as balanced?

Thanks for the post.
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Old 16th January 2006, 09:32 PM   #5
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Default Balanced Source?

Hoping your cd player (or source) is a balanced too. As you may have read, i've tried the zen v4 in both SE and balanced setups and there's no doubt that balanced is the way to go.

For my SE tube amps, the house electrical mains wires flicker with a constant 'flick... flick.. flick" which I can hear through the speakers. But when going balanced, all such nasties are gone.

Your 5.25" heatsink sections should be fine AS LONG as you space your FETs out. On the hottest summer day, the middle heatsinks do get toasty. It may be worth reading how 'extending trasistor leads' off from a PCB may not be the best idea. Something to do with the extra leads picking up RF signals. Though I doubt such problems would apply if you're all balanced.

As of now, I don't know of anyone else on the forum that has built monobloc 'balanced' zen v4. But I do know that there are a few of those that built them as a SE amp and have had problems firing them up (parts overheating). If the boards don't work alone in SE, then it's fat chance getting another board for balanced operation to work it together.

When you do tie say the + channel to the - channel on the speaker outputs. Make sure that connection is a solid connection using heavy guage wire and soldered or tightly held down.

I can assure you that once you have them built, I think it even beats the old SOZ hands down.

BQ
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Old 16th January 2006, 10:44 PM   #6
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Default Re: Balanced Source?

Quote:
Originally posted by Super_BQ
Hoping your cd player (or source) is a balanced too. As you may have read, i've tried the zen v4 in both SE and balanced setups and there's no doubt that balanced is the way to go.

For my SE tube amps, the house electrical mains wires flicker with a constant 'flick... flick.. flick" which I can hear through the speakers. But when going balanced, all such nasties are gone.

Your 5.25" heatsink sections should be fine AS LONG as you space your FETs out. On the hottest summer day, the middle heatsinks do get toasty. It may be worth reading how 'extending trasistor leads' off from a PCB may not be the best idea. Something to do with the extra leads picking up RF signals. Though I doubt such problems would apply if you're all balanced.

As of now, I don't know of anyone else on the forum that has built monobloc 'balanced' zen v4. But I do know that there are a few of those that built them as a SE amp and have had problems firing them up (parts overheating). If the boards don't work alone in SE, then it's fat chance getting another board for balanced operation to work it together.

When you do tie say the + channel to the - channel on the speaker outputs. Make sure that connection is a solid connection using heavy guage wire and soldered or tightly held down.

I can assure you that once you have them built, I think it even beats the old SOZ hands down.

BQ

My source in NOT balanced (its a SCD-777es), but my preamp is a BoSoZ which is supposed to convert SE to balanced. I have mounted the MOSFETs off the circuit board in my current bi-amped parallel Zen V2 (Zen Revisited) without any problems. I believe in Nelson's articles he stated that these designs do not have problems with RF and can be built in a wooden box. Mine will be within an aluminum enclosure composed on my heatsinks and 1/8" aluminum sheet (somewhat similiar to yours). This signal box is separate from my outboard powersupply and the chassis is connected to ground (separate from signal ground).

I am glad to find you have tried SE and balanced and have a strong opinion that balanced is better.

THanks!
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Old 16th January 2006, 11:37 PM   #7
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Of course the best results I ever got from Zen and ZV4 is
balanced and paralled, using 4 channels.
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Old 16th January 2006, 11:41 PM   #8
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Why is balanced better?
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Old 16th January 2006, 11:49 PM   #9
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Linearity
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Old 17th January 2006, 12:16 AM   #10
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Quote:
Originally posted by Nelson Pass

balanced and paralled, using 4 channels

4 channels for the left speaker
Another 4 channels for the right
Total 8 ?
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