Pass B1 CLONE build completed and happy - diyAudio
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Old 24th October 2012, 08:10 AM   #1
omishra is offline omishra  India
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Default Double Decker: Pass B1 CLONE build completed and happy

This is my first build I am posting here. I would like to thank Nelson Pass for making this available for us.

Let's start! I won't describe it in words. Rather than let pictures speak themselves.

All PCB boards were assembled for mounting in chassis. All PCB layouts are designed by me except source selector and of course PASS B1 Clone is from NP. Thanks to Uriah offered significant help during initial build of LSA.
Image591.jpg

I started with metal box and perforated screen for making DIY chassis.

Image592.jpg

After cutting in sizes time to bend and make it in shape to fit in everything.

Image593.jpg Image594.jpg

There was some issue with one source (CDP) causing drop of LF because of LSA impedance of 13KΩ exposed to source. To hide the LSA behind buffer I added SSP - DIY Super Simple preamp (from another forum). This is another version from previous one where I used SSP at the input to accept selected source and drive LSA within PASS B1 where B1 driving output power amp.

e.g. Source -> (SSP->[LSA->B1])->Power amplifier

Image732.jpg Image733.jpg

This sounded excellent. But SSP is having unity gain which was not my requirement, I wanted no (zero) gain, pure buffer. Hence I replaced SSP with another bulky B1 (shared PS with first B1).

Image745.jpg Image746.jpg Image747.jpg Image748.jpg

Now it looked like: Source -> (B1->[LSA->B1])->Power amplifier
in above statement, PS is not shown but present there and
() - inside preamplifier
[] - second B1

This made input impedance of B1 exposed to source (1MΩ) and first B1 drives to LSA. Second B1 shows output impedance of 50Ω, drives power amplifier. This make it B1 buffer at both the ends, make any source in the world happy by means of very high input impedance. All power amps are drivable with very low output impedance and LSA in control of volume level.

This made no loss of frequency response and adequate driving of source and power amp made life easy with net result cleanest possible I listened in my setup.

Last edited by omishra; 25th October 2012 at 06:47 AM.
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Old 24th October 2012, 08:16 AM   #2
omishra is offline omishra  India
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This is the final outcome of the project.

Image749.jpg Image750.jpg Image751.jpg

Knobs were sourced from fleabay and Faceplate was homemade by me. I used 6mm Aluminum plate which is fixed by 4X M3 screws from behind. I have plan to anodize it but so far put one thin layer for metal primer, 2 thin coats of silver color spray (available for Car paint shop) and 2 coats of clear coat.

Last edited by omishra; 24th October 2012 at 08:24 AM.
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Old 24th October 2012, 12:11 PM   #3
adason is offline adason  United States
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nice
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Old 24th October 2012, 01:47 PM   #4
Marra is offline Marra  United Kingdom
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Is the R core from Schilchar?
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Old 24th October 2012, 02:38 PM   #5
omishra is offline omishra  India
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Quote:
Originally Posted by adason View Post
nice
Thanks!
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Originally Posted by Marra View Post
Is the R core from Schilchar?
Yes, its from franchise of Schilchar.
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Old 24th October 2012, 03:16 PM   #6
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Very nice. how does the LSA work out? Is it a good match?
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Old 25th October 2012, 06:46 AM   #7
omishra is offline omishra  India
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Quote:
Originally Posted by vdi_nenna View Post
Very nice. how does the LSA work out? Is it a good match?
Thanks!
LSA do match nicely. Only problem is it exhibits low impedance for source if exposed to source without any buffer. I could not figure out why LF was getting lost for CDP but addition of source buffer solved that issue. Definitely it was working fine with all other sources in absence source buffer too.
Now how LSA works? Its very smooth and transparent. I used linear pot so I can have better control at lower volume levels. Matched LDRs do trick for balancing stereo image.

Uriah offered significant help during initial build of LSA which was part of group buy we ran at another Indian forum.

Last edited by omishra; 25th October 2012 at 06:48 AM.
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Old 25th October 2012, 07:24 PM   #8
KT is offline KT  United States
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Very nice! But how does it sound?
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Old 26th October 2012, 04:04 AM   #9
omishra is offline omishra  India
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Very nice! But how does it sound?
Thanks! It sounds very clean. Background is dead silent. Frequency response is flat and no gain - no loss of signal level. Overall total transparant within chain. No coloration of sound, I can listen every detail of Music. And this exposed limitation of speakers which are DIY. Now working on GR research speaker DIY as well as F5turbo V2.
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Old 30th October 2012, 05:55 AM   #10
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which is the board you used for input switching?
i'm ideally looking for a IR remote input selector to use with my B1
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