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Old 27th January 2013, 05:48 PM   #11
osscar is offline osscar  Latvia
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b1 is relatively simple - This should not sound bad if you do everything correctly.
Here's my b1 of all scrap that I had (matched Jfets) :
160Khz square wave, 1Kand 10K spectrum with EMU USB card ( simple LM317 PSU).
sound sweet
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Old 27th January 2013, 06:43 PM   #12
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Quote:
Originally Posted by Telstar View Post
Well, your signal is passing through several more components, it's obvious that a slight degradation will occur. In your case is quite more than that, so probably something is not right in your B1.

But, did you need a buffer in the first place? Maybe redoing the output stage of the Buffalo would have been a better option (along the lines of the D1 perhaps)?
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.

Last edited by murphythecat8; 27th January 2013 at 06:45 PM.
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Old 27th January 2013, 06:46 PM   #13
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Quote:
Originally Posted by Nelson Pass View Post
I take it that you did not measure the Idss of the Jfets before putting them in?

no I didnt, but they were matched though...
however, my B1 do not sound wrong, its just aht I have a slight degradation all over the bandwidth but I know its normal but its affecting a bit the tonality and the clarity and the inner details...

should I still take them out and measure them?

Last edited by murphythecat8; 27th January 2013 at 06:52 PM.
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Old 27th January 2013, 07:15 PM   #14
tinitus is offline tinitus  Europe
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must be a biasing issue ?
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Old 27th January 2013, 07:25 PM   #15
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Quote:
Originally Posted by murphythecat8 View Post
hi everyone
I have build a pass b1 and I'm not totally convinced. I have however used good quality caps but I have used regular resistors.
The pre amp really take away inner details, resolution, clarity. the bass is less defined, the highs more strident. It is not a night and day difference. lets say, it goes from a 10/10 to a 8.5/10
What can I do. would changing the resistors could really bring back everything, or the design simply hold me back?
What are the most important resistors in the pass b1? if anyone can point me to the most critical resistors, that would be great, I use a noble pot, good interconnects.

My chain is quite ordinary for now: buffalo-- ckIIII-- ath m50

any help would be great!
If the B-1 you built is "taking away inner details" along with "resolution" "clarity" and "less defined bass" it has a problem. What board did you use, might post some pics of its construction and wiring.

The B-1 is a super simple circuit, and when properly working should take virtually nothing away in terms of details, clarity, bass and resolution....this circuit, properly done excels in these areas. Its only fault for me is that being a buffer, it has little or no gain.

In some of my setups, this lack of gain is a little problematic. Even when the overall volume is basically sufficient, the system can sound like its missing some "drive" for lack of a better word, something that is there in spades with a pre with gain.

In other setups, (power amp of normal gain, unlike my standard F-5's 15 dB) it does not seem to have this problem, and there is plenty of volume knob to get past "too loud."

If you are driving a power amp that isnt particularly high gain, or speakers are not very sensitive, perhaps this is the effect you are experiencing? This pre should be very transparent, warm and not strident at all, with powerful bass. Some of the "Bass power" suffers in the above mentioned setups lacking gain, that big pressurized rolling bass effect and its reverberation are reduced when compared to the same setup with a pre with gain. With a power amp that has higher sensitivity, and or speakers with similar high sensitivity this is not a problem in my experiences with B-1.

Mine is a Pass Labs board with the matched fets from the Pass site.

Russellc
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Old 27th January 2013, 07:31 PM   #16
tinitus is offline tinitus  Europe
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please quit the nonsense about component quality
and read Nelson's post again
just because the jfets are matched doesn't mean they are right
might be able to 'adapt' them(adjust), but I will leave that to others
why do think the master ask you about the idss
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Old 27th January 2013, 07:33 PM   #17
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ok. It doesnt sound harsh at all, but the highs are a little more strident. the bass is plenty and powerful, but again, not as perfect, but its huge bass none the less. I'm talking here about the last 5% os perfromance Im lacking. I know that its impossible to have a totally transparent pre since I use a nobel pot, and theres caps and intereconnect that will change minimally the sound.
honestly, with my speakers, the difference is minimal and hardly noticeable, but with headphones, I can hear a slight difference, but just to be sure, what should I do to clear my head of this? What do I need to measure, the jfets? what else? Also, I had used cheap wires to wires the preamp, I need to redo everything to replace all the connection, that should help.
I did not use any board, its point to point builded
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Old 27th January 2013, 07:34 PM   #18
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Quote:
Originally Posted by tinitus View Post
please quit the nonsense about component quality
and read Nelson's post again
just because the jfets are matched doesn't mean they are right
might be able to 'adapt' them(adjust), but I will leave that to others
why do think the master ask you about the idss
k, thanks, I will measure the idss. but isnt that non sense since im not saying the pre sounds wrong...
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Old 27th January 2013, 07:42 PM   #19
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by murphythecat8 View Post
.... im not saying the pre sounds wrong...
no, but you don't know if it sounds like it should either
from fooling around with biasing the simple jboz, it sounds to me like it could relate to the voltage-current balance, and resulting in wrong biasing
but I'm only guessing, yes
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Old 27th January 2013, 09:43 PM   #20
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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.
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