ESP Death of Zen preamp vs BOZ

[gretzteam]

Hi!
I'm about to build a preamplifier and I'm wondering which of these two I should choose :
1) The Bride of Zen from Passlabs
2) ESP project#37 Death of Zen Preamp

Both preamp have great specs. I already built a Leach amplifier and I'd like to build the best preamp that would goes with it. I read that the Bride of Zen has a high gain (15db) to match the Son of Zen that doesn't have a high gain for an amplifier. The Esp project has a lower gain (10db). Should I take the ESP project for this reason (I guess my leach amplifier doesn't need a high input).

Thanks a lot for your ideas!
David

[Lisandro_P]

Originally posted by gretzteam
Both preamp have great specs. I already built a Leach amplifier and I'd like to build the best preamp that would goes with it. I read that the Bride of Zen has a high gain (15db) to match the Son of Zen that doesn't have a high gain for an amplifier. The Esp project has a lower gain (10db). Should I take the ESP project for this reason (I guess my leach amplifier doesn't need a high input).

Well, both amps have a low input sensitivity (much lower than the Leach)... you can tweak with both preamps' gain (i beleive that the DOZ pre had info on doing just that; haven't checked on the BOZ), without problem. On the sonics.... well, i haven't heard either, but they're both superb designs for sure.

[bawang]

Having built both DoZ and BoZ preamps, yes, both the preamps' gain are adjustable by changing the value of one resistor (the 1K 3W resistor in the BoZ). In the BoZ, by changing the value to 600 ohms (parallel 2 units of 1.2k), this will solve the unsymmetrical clipping problem too, giving you a gain of about 5 (about 14dB, if I'm not mistaken) unloaded. Nelson Pass recommends a pot at the input to eliminate the clipping problems that may occur with too high an input level to the BoZ (for example a CD player at 2V!). The output of the BoZ will clip at around + - 15V peak.

Unless you are using a source with low output (ie below 500mV), a gain of 3 (10dB) is more than enough for the Leach Amp, which needs an input of 2V for full output.

All things said, both are good, solid designs and sounds good too! I'm using both, but I may prefer the DoZ preamp just for its negligeble heat dissipation (in 30 degree C weather, it IS a major consideration) and extremely compact size (if you buy the boards from ESP).

As for the "another few zeros after the decimal point" distortion, I have to confess I can't hear the difference between 0.1% distortion and 0.01% distortion. Maybe I need to upgrade my ears for a change......

[grataku]

I built the DoZ, sounded like crap (IMHO), very bright, dry, definitely annoying to my ears. That's not to say that Rod did a bad job. I used off the shelf components and I made my own pcb. Maybe it requires very careful component selection to sound better, I don't know. From my experience I can't recommend it.

[gretzteam]

Having built both DoZ and BoZ preamps, yes, both the preamps' gain are adjustable by changing the value of one resistor...

I'm not too sure what you guys mean when you're talking about tweaking the preamp gain. I'm a hardware guy so I don't know much about the theory of audio preamplifiers.

Do you mean that since the Leach does not need a high input, I should diminish the gain of the preamp I decide to build? If so, what would be the gain I'm looking for?

Thanks a lot

[Lisandro_P]

Originally posted by gretzteam
I'm not too sure what you guys mean when you're talking about tweaking the preamp gain. I'm a hardware guy so I don't know much about the theory of audio preamplifiers.
Do you mean that since the Leach does not need a high input, I should diminish the gain of the preamp I decide to build? If so, what would be the gain I'm looking for?

Well, this is the idea: input sensitivty is the signal voltage needed to drive the amp at full power; for the leach amp that's about 1,5 - 2V and for the DOZ, it was something like 6V... So, yes, you need to reduce the gain (or keep the volume pot down ). Gain in preamps is usually set by one or two resistors, so it's no big deal; it's just a matter of changing them. As bawang said, a gain of 3 or 4 would allow a 500mv signal to drive the Leach to full output, so i beleive that would fit your requirements.

The exact details for this mod escape me (i haven't built either... yet atleast), but i'm sure they're explained on their respective web pages.

BTW, bawang, how would you compare both preamps sonically? I'm curious, having to build a preamp in the near future...

[bawang]

Lisandro, I may be blasted off the earth for saying this, I am a true believer of double-blind AB comparison where you keep all other parameters (or devices, including volume level) constant, changing ONLY the component under test, and trying to identify which component is being used. That said, it is a bitch trying to keep all else constant, especially the volume. A decibel meter and a pink noise generator will help tremendously, but I have neither.

What you can't hear won't hurt you (or your wallet!), this is the final judge. In all my years of indulging in HI-FI (or HI-FIey, if you will), the component that really stands out in the double-blind AB comparison test, assuming all other components are competently designed, manufactured and operating within their designed limits, are the loudspeakers. But of course, each one of us have our own preferences in the quest for the perfect sound (for our own ears).

What is perfect for one may be lousy for another. As long as you're happy with it, so be it! Enjoy it for as long as you can, until you decided to change. But of course, the art of tweaking is always a pleasure...........

[JoeBob]

Well considering the fact that all the ESP projects I've undertaken have turned out wonderfully (unfortunately I haven't built the DoZ though) I can say that Rod does an amaizing job and will answer your questions too (and I didn't even buy any boards from him). Although I hear that the BoZ is really good as well. But when it comes down to it, how you build your pre-amp and what components you use will probably matter more then which of these two projects you choose to embark on, since they're both apparently excellent...

[Lisandro_P]

Originally posted by bawang
(...)

What is perfect for one may be lousy for another. As long as you're happy with it, so be it! Enjoy it for as long as you can, until you decided to change. But of course, the art of tweaking is always a pleasure...........

Of course... i just wanted to know how they sounded to YOU. Anyway, i haven't built neither as i said before, but i am sure they both perform excellent.
On the subject of preamps, "Surf, Sun & Sound" recently pointed me to a series of simple, discrete preamps by John Linsey Hood that look quite promising too, so i'm still trying to make up my mind on that

[bawang]

Good luck, Lisandro. And don't forget, enjoy it! Don't let the technicalities cloud your eyes.... There's always something to be said about stuff that you built with your own hands..... what I refer to as sentiments...... Oh, keep us all informed.