I m too not sure about my pass b1

[tinitus]

To me it sounds fine, maybe even nice but somehow flat and uninvolving.

when that happens I usually blame the speakers

 

[murphythecat8]

I built B1 some 1,5 years ago and also wasn't satisfied with it sonically.

I used the best parts with Caddock resistors Siemens MKV coupling caps, cardas wire, Cardas solder, Matched J fets etc.. I powered it off batteries and used stepped attenuator as volume control.

To me it sounds fine, maybe even nice but somehow flat and uninvolving. The music does not flow, no emotion, no extreme 3D and separation.
Classic Aleph P 1.0 I have sounds much better to me.

I tried to come back to B1 many times but it's always the same. I still have it somewhere laying around.

Just build another /diffrent project, maybe it's not for you.

k thanks for that, what would be a better project for sure?

 

[zygibajt]

when that happens I usually blame the speakers

But not if that doesn't happen with another preamp in the same system.

 

[zygibajt]

k thanks for that, what would be a better project for sure?

I have no idea, it probably all depends, i belive some are extremely happy with B1 and it depends on the system and preferences probably, it is just you are not alone what i wanted to say. I'm not impressed with B1 that's it, does not work for me. I belive some Pass production preamps to be better than B1, maybe not in every system but most. I have no idea what to recommend, maybe others can help what other preamp might be worth of building if B1 does not work for some.

 

[Nelson Pass]

Assuming that it is working correctly, the B1 is very neutral. It's not even
really a preamp - it's a buffered volume control. There are plenty of people
who aren't looking for that, and it's no problem by me if they prefer something
else.

 

[AndrewT]

no I didnt,..............................

should I still take them out and measure them?

I told you many posts ago to measure the Vgs. See post4.
Have you done that yet?

 

[tinitus]

But not if that doesn't happen with another preamp in the same system.

on the contrary

..... what would be a better project for sure?

to bring life to dull sound... 6V6 tube line pre (by Salas)

 

[kroyin]

You use a pot with the B1 ? If yes is it mono/stereo and what is the rated impedence of the pot(s).

I had a lifeless B1 (again very subjective opinion totally based on one's chain) with optical volume control (impedance of ~13k). Swapped the optivol with 2 mono Log Pots of 25K impedance each and things became a LOT better

 

[tinitus]

...... with 2 mono Log Pots of 25K impedance each and things became a LOT better

which I guess makes it more a matter of your source output

 

[kroyin]

Well i'm not so sure, with DCB1 and the same source and the same optivol, the performance is extremely good.

But then what do i know

 

[tinitus]

a different power supply most likely makes a small difference, yes

 

[Telstar]

how can you know if mine have a problem? As I said, the sound is good, they is no obvious flaws. However, the high are slight more harsh, the vocal seems a bit more in the background. its small differences really. goignj from 100% to 90$ I would say...
yes I do need a preamp. I have two outputs (one for my mid and tweeter and one for my bass, im bi-amping my speakers) and I added a crossover in one of the outputs.

Well, you stressed the flaws to the sound with the buffer inserted, therefore most people thought you have a problem in your B1.
According to your signature I assumed you were using headphones.

 

[murphythecat8]

k thanks guys, I'm in the middle of my three-way project, so I will be playing with my pre within a month.
I'll report back.
I use a 100k noble pot

 

[tinitus]

....and I added a crossover in one of the outputs.

..... I do hear degradation when the sound oes thru the preamp versus going straight to my headphone amp...

ahh...I take you mean when using your headamp as pre....and you have the same biamp/xo setup on your head amp ?

 

[KatieandDad]

There's a lot of ground there being covered by the impedance of the volume pot. I experimented quite extensively with mine and 100K at the input gave the best results.

If you go to the pass DIY web site and look at the original design the pot should be at the input of the B1. It does work at its best there.

LDR was rubbish. ALPS was better, decent Ladder Attenuator was best.

 

[murphythecat8]

ahh...I take you mean when using your headamp as pre....and you have the same biamp/xo setup on your head amp ?

I have a selectable swicth that allow me to run fullrange or to cross the signal around 300hz. this output is for my mid/tweet, and I ahve another output going in my subamp with crossover .

 

[tinitus]

did you considered a trafo for signal splitter ?

 

[ra7]

Do you know the input input impedance of the two amps the b1 is trying to drive?

 

[murphythecat8]

lol, no. thanks for the help now, I may have asked a bit too early for guidance.
thing is, right now, as we are speaking, I am rebuilding my push pull tube amp with a whole new design and also just finishing my three-way project (I actually finished the crossover yesterday!). I will be back to the preamp situation once everything is done and that im ready to really concentrate on the pre amp situation. I will probably build a tube pre to compare to get my conscience clear.

 

[AndrewT]

Murph,
have you measured Vgs yet?