Bride of Zen, Bride of Son of Zen

I believe this has been discussed from all different pespective and there isn't any one answer.

I would suggest ....... do a search on the subject ...... even though I know that the search feature would not necessary gives you all the thread that you want ....... so ... may be try different search using different wording .....

I have a BOSOZ and I like it very much.
 
If you are looking for an unbalanced to balanced converter, the BOSOZ will perform better with a CCS in place of R3-R6. You won't need more than 20V on the negative rail for that.

There are also X versions and cascoded versions around as well as Cascoded, CCSed and Xed. If you go far enough tarting it up it pretty much becomes an Aleph-P1.7. The standard version sounds pretty darned good, even using it as SE to balanced converter.
 

vdi_nenna

Member
Paid Member
2000-10-10 7:27 pm
PA, USA
I've built both. The BOSOZ is the better choice, but is at least 3 times as complicated being that it's balanced and will need associated parts and an expensive volume control or multiple volume controls. (Dont go cheap on volume controls. It has a great deal to do with the sound of a preamp.) The power supply is more complex and needs more parts and transformers.

There's more depth to the BOSOZ in terms of imaging and delivery of tones from what I remember, and with using unbalanced connections, so it was a head to head comparison.

I have the BOZ boxed in my garage and looking for a home. :D
My BOSOZ was sold last winter.
 

MNYankee

Member
2015-11-12 10:04 pm
Hi guys,

I am building a BOSOZ preamp with my son. Already have a B1 that we built. My son needs more gain. I have some questions about the 5 Pots. I am building this version-

http://www.firstwatt.com/pdf/art_bosoz.pdf

with boutique components such as Mundorf M-Lytic and Obbligato gold caps. Resistors are Audio Note non magnetic tantalums and shinkoh tantalums, Kiwame, Amtrans and Takman Reys.

Which pot do I use as a volume control and can I use an alps or tkd pot? I want a remote volume control. I already have a spare TKD 2CP-2511 MC motorized 50K pot and an Alps Blue Velvet 50K motorized pot.

Can I combine some of the pots into 1 two channel pot?


I see from the schematics and parts list that the pots are linear. The Alps and TKD's are logarithmic. Does it matter?

I have read that this preamp has a lot of gain. Would it be better to use lower value pots at P3 and P4?

I am a novice at this. This build is probably a little over my head. The B1 was easy and came out sounding great. Any help is greatly appreciated.
 

vdi_nenna

Member
Paid Member
2000-10-10 7:27 pm
PA, USA
BOSOZ requires 10k pots. 50k might be too high.

TKD and Alps will work. You'll need 4 monos, 2 stereo pots or a 4 deck pot.
Discrete stepped attenuators are the way to go. Discrete costs more, but you'll know where your money went. On the low end of cost, 4 mono wiper type pots will probably be more accurate since you can dial them in independently.

Log pots are ok. They are configured to have an increase in volume that's more natural to our ears. Linear will work, but when you turn it up, it will be a more abrupt volume adjustment.

Adjusting the gain isn't hard. I don't know how to do it. Probably require scaling the a pair of resistors. one of the resident rocket scientist could probably figure it out easily by looking at the schematic. ;)
 

MNYankee

Member
2015-11-12 10:04 pm
put 10K pots there

that's your volume pot

instead of P3 and P4 put 5k fixed resistors ...... or leave them out and replace R11 and R12 with 5K

P5 is trimpot for gain setting

For P1 and P2 can I just use 1 stereo Alps Blue Velvet pot as I want a motorized remote volume control.

If I use 5K fixed resistors for P3-4, what wattage?

Thanks for the help,

Larry
 

MNYankee

Member
2015-11-12 10:04 pm
Got I think! I will use a stereo 10K motorized pot for p1 and p2 and 5K resistors for p3 and p3. Then another pot for p5.

Pass recommends a 500K pot for P5. If I use an Alps, will 250K be ok or should I just buy the recommended cheap 500K pot that is in the original parts list?

I would like to use ladder type pots but I already have too much money in the boutique caps and resistors. I can always add them latter on if we don't like the sound.

The preamp is going to be paired with a Parasound A21 amp and a DAC with 2.1mv input.