Zen Balanced Line Stage Balanced vs Unbalanced


2001-12-15 3:07 am
I have recently been trialing my new Balanced Line Stage in either balanced or unbalanced output to the Aleph 5.

Firstly, I have to say this is the best sounding pre I've heard for some time. Its quite a smart performer.

Why I did not build this ages ago is beyond me. Cheers Nelson.

Unbalanced in/out appears to sound a bit warmer, and unbalanced in/balanced output less warm and more crisp and clinical in comparison.

I maybe correct in assuming balanced output mode cancels some of the second harmonic disortion of SE operation?

I prefer a bit of 2nd harmonic maybe

As to my choice of parts its straight out of the article.

I'm using an Allen Bradley conductive plastic 25K dual gang pot on the input (unbalanced input mode) and the shunt attenuator (Aleph P) using (2) Lorlin 2 pole 6 position rotory switches with resisitors of 4.3K, 2K, 1K, 499R, 240R 120R.

This seems to work and does not appear to effect sound quality.

I intend to build Panos's relay version of the attenuator for 64 step multi stepped attenuation.

My output caps are Black Gate C series 10uf 50 volt, they are billiant!


You're right,it's a wonderful sounding unit.
Why not try some SCR capacitors for the output?I realized 2 versions of the ZLS,one with SCR capacitors and one with Arcotronics film cap grey version.I much prefer the SCR version than the other...
Some Blackgate types are not for coupling use.But I guess the Silmic silk separator series is OK for the purpose,and we can find some special for coupling use Blackgates.I would use a small MKP decoupling cap parallel however.



2001-12-15 3:07 am
This is interesting but the BOSOZ is a much simpler design than the Aleph P and the extra complexity hardy seems warranted.

A quick question for Nelson.

The idea of the shunt relay driven volume network like the P is appealing for means of construction and precision rather than say two 5K dual gang pots.

Do you consider any performance penalities over the 5 K pot other than reduced voltage swing?


I've since arranged proper cannon leads and terminations for the pre and power amp with the input - negative shorted on the input of the pre amps.

I trust this is the correct way to run the pre with unbalanced inputs.

To my ears the sound is quite clean and dynamic.



This a good question so why not just ask for an A/B on the factory floor during lunch hour!

I suppose this is what diy is all about though, you have to make it to find out.

But from what I can see the P 1.7 is a commercial offering designed operate in either balanced/unbalance mode without any penalties referring to "optimal operation" in either mode according to the manual.

I think this refers to the additional components for best common mode rejection with unbalanced in/ and say balanced out.

However, the inherant SE operation appears in both designs so on paper one could only assume subjectively they would be slightly different but not major league, ie using fet current sources, input cap etc.

I'm still not sure why, but un bal in, unbal out sounds noticably different to unbal in , balanced out and would like to hear from the others if they have similar experience?.

The mids are cooler and recessed, the bass is much tighter and the top end is more agressive.

Perhaps I have a diy cremlin in there some where


Hey Guys,

DIY Boo boo.

Balanced mystery solved.

I found out why my Balanced operation was sounding so different..

I was in a hurry to commision the BOSOZ for balanced mode and recently discovered my balanced cable and XL connectors were wired incorrectly (I think I had hot and earth crossed at least).

I'm surprised it worked at all.

As to the sound now.. its magic!


Speaking of BOSOZ balanced output ....

Recently I have tried different set up of some of the stuff that I've built so far. I have mentioned a couple times in the other threads that my $500 Magneplanar MMG speakers sounds a little light in the bass region and I have always supplement the Maggies with a subwoofer.

Today, I hook up my BOSOZ (balanced out) to my Aleph 2 (balanced in) and I could not believe the amount of bass that I'm hearing from the $500 Maggies. I have used the Aleph 2 with some other pre-amps for the Maggies before but today is the first time I tried it with the BOSOZ. So, I'm very sure the much improved bass is due to BOSOZ. I'm beginning to wonder why BOSOZ makes such a big difference.

I was wondering if you guys have the same experience with your BOSOZ that are hooked up to "non-conventional" speakers.

And by the way, there isn't any turn on/off thump with this set up.

My speaker are a dynamic piston range system but hardly conventional.

My previous pre out source was a Harman Kardan AV preamp model PT2500.

The BOSOZ slaughtered it, particularly in the bass clarity and dynamics, the sound is just so real.

By the way the Harman/Kardan uses NE5532 chips throughout, yuk says Nelson and rightfully so, they really suck compared the IRF610 Diff pair combo.

I have not A/B'd recently with the old preamp, but when the program material demands it , I can almost count the cycles on the bottom end.

PS I am waiting for Waynes remote passive volume control article which I hope I can incorporate into the BOSOZ. (For my Xmas stocking please)

These switched attenuators are way over the top, and there's no remote option. and my Lorlin 2 pole 6 position rotary switches just won't do.




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diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
martinschki said:
sorry for the stupid question:

how can i use the advantage of the BOSOZ + Aleph5 connected balanced when my CD Player and my turntable has unbalanced Output (Cinch)??

Or should I build another Pre? (But everyone here praises the BOSOZ, so I also want to go for one!)


Yes, you can take advantage of the BOSOZ and Aleph 5 connected balanced with an unbalanced input to the BOSOZ. It can essentially be used as a unbalanced to balanced convertor. Read the article...


I assume you have not built the pre yet, if so would run with the BOSOZ as this is proven design with boards available or simple enough to make point to point wiring.

Here is a shot of my Aleph 5 with Hi Cap power supply, it runs very nicely and I may convert to the Aleph 60 or a small Alpeh X!

The Aleph 5 is still a great amp though and practical for most to contruct.



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