Nelson Pass B-1 preamp kit

wushuliu · « **Reply #120 on:** 16 Mar 2010, 04:30 am »

Quote from: Mariusz on 12 Mar 2010, 05:18 pm

Awesome.
Surely there must be at least few fellow members speculating about this option.
Having owned (still using) few components with BPS, I can see why someone would like to explore this option or even implementing it into basic design.

That is probably what I like about this project.

- you can start with basic design
- refine it as you get better and more comfortable with DIY essentials
- spend as much (or as little) as you like/can afford

Mariusz

Absolutely. There are now spin-off designs based on the B1 on diyaudio that are suppose to
sound even better. Many thanks to Nelson Pass for making this design 'open source'.

Mariusz · « **Reply #121 on:** 16 Mar 2010, 04:42 am »

Quote

Many thanks to Nelson Pass for making this design 'open source'.

Obviously his contributions to DIY audience and forums are priceless.... literally.

P.S
you're doing great job with your tutorial

Cheers
Mariusz

wushuliu · « **Reply #122 on:** 16 Mar 2010, 05:31 am »

PS caps and battery power now covered in the reserved on page 5...

yammy1688 · « **Reply #123 on:** 17 Mar 2010, 02:02 am »

I've built this exact combination and it is indeed excellent. Used one of the ebay B1 kits, but bypassed the POT, and using the LDR /LSA kit from udailey. The B1 fleshes out the sounds and the LSA just helps keep things nice and clear.

Quote from: sondale on 15 Mar 2010, 09:39 pm

wushuliu,

I published a few photos of my B1 / LSA build a few days ago specifically to show how I used batteries. I had started building another B1 for this thread but stopped because of your excellent contribution.

As far as sound quality is concerned I think the B1 is excellent, as far as a simple 'pre-amp' is concerned the B1 takes a lot of beating. I have used valve pre-amps and switched to a Promitheus TVC (Transformer Volume Control) Pre-Amp - I found the B1 better (using ALPs pots) and the LSA/B1 even better.

The sound is open, detailed (but not agressively so) with a wide and fairly deep soundstage. Neither the B1 nor the LSA seem to add anything to the signal. A good test is to listen to some music through headphones and then insert the B1 into the signal path with the volume at maximum (the signal should be roughly what is was before) and listen again - you will be surprised at the very small change (if any) that there is.

The B1 without a potentiometer is very useful as a pure buffer - as far as I am aware (but I could be wrong) Nelson Pass designed the B1 for use with the original LightSpeed Attenuator - which may explain why they go together so well.

Sorry to push the LSA but I think once people have built the B1 and are feeling adventurous then it is the next logical step. I will start another thread for this shortly.

I have not seen the Ebay board - do you have a link?

Alan

atroder · « **Reply #124 on:** 17 Mar 2010, 02:49 am »

Quote from: yammy1688 on 17 Mar 2010, 02:02 am

... and using the LDR /LSA kit from udailey.

Can you please provide a link to the udailey kits? - Thanks.

mgalusha · « **Reply #125 on:** 17 Mar 2010, 02:52 am »

Quote from: atroder on 17 Mar 2010, 02:49 am

Can you please provide a link to the udailey kits? - Thanks.

Uraih's site

xecluded · « **Reply #126 on:** 17 Mar 2010, 04:38 am »

Quote from: atroder on 17 Mar 2010, 02:49 am

Used one of the ebay B1 kits, but bypassed the POT, and using the LDR /LSA kit from udailey..

How do you bypass the pot. I have the LDR from udailey as well and want to do the same. Do you feel that the sound would be a lot better for not using the pot. Thanks.

sondale · « **Reply #127 on:** 17 Mar 2010, 09:52 am »

Quote from: xecluded on 17 Mar 2010, 04:38 am

How do you bypass the pot. I have the LDR from udailey as well and want to do the same. Do you feel that the sound would be a lot better for not using the pot. Thanks.

There are two ways to 'bypass' the pot on the B1, firstly you can put the LDR-based circuit in the same position as the pot, secondly you can effectively short the pot and put the LDR-based circuit at the input to the B1.
I did the latter as I wanted to switch more than two sources. I think it is defintely time to start a new thread on the LDR-based attentuator.
I will do so this evening - I had been waiting for some new parts to arrive and to start new builds but I think that a new thread will allow people to post without taking up space in this B1 thread.

To answer your other question - yes either using an LDR-based attenuator or no pot at all will sound better - I built the B1 originally in the same way as wushuliu had demonstrated and liked it a lot but the LDR-based version is better.

Alan

xecluded · « **Reply #128 on:** 17 Mar 2010, 06:15 pm »

Great. I will try the "short the pot and put the LDR-based circuit at the input to the B1" way too. Thanks Alan.

sondale · « **Reply #129 on:** 17 Mar 2010, 06:26 pm »

Quote from: xecluded on 17 Mar 2010, 06:15 pm

Great. I will try the "short the pot and put the LDR-based circuit at the input to the B1" way too. Thanks Alan.

I will quickly draw a diagram and send it - please wait!

sondale · « **Reply #130 on:** 17 Mar 2010, 06:55 pm »

xecluded,

If you do as you say then you can only use one input, on the board the volume control is after the input selector, so shorting the pot means that both inputs are running full tilt, the one with the LDR-based attentuator will function normally.

As a temporary measure this is OK - just connect one input.

By shorting I mean take the wire on the output leg of the pot (the one that goes to W on the pcb) and move it to the input leg on the pot (the one that goes to CW on the pcb) so now you have two wires on the input leg of the pot - you have to do it this way rather than simply connecting input to output on the pot. I am not sure what would happen if the pot is still in circuit and you twiddle it.

The alternative is to change the pot to a resistor - detail in the new thread - when I can it together!

Alan

sondale · « **Reply #131 on:** 17 Mar 2010, 07:07 pm »

diagram: -

sondale · « **Reply #132 on:** 17 Mar 2010, 08:06 pm »

Please note that I have started a new thread 'Optocoupled Attenuator Build' in which I will try to answer the various questions relating the much mentioned LSA.

Alan

xecluded · « **Reply #133 on:** 18 Mar 2010, 04:25 am »

Quote from: sondale on 17 Mar 2010, 06:55 pm

xecluded,

If you do as you say then you can only use one input, on the board the volume control is after the input selector, so shorting the pot means that both inputs are running full tilt, the one with the LDR-based attentuator will function normally.

As a temporary measure this is OK - just connect one input.

By shorting I mean take the wire on the output leg of the pot (the one that goes to W on the pcb) and move it to the input leg on the pot (the one that goes to CW on the pcb) so now you have two wires on the input leg of the pot - you have to do it this way rather than simply connecting input to output on the pot. I am not sure what would happen if the pot is still in circuit and you twiddle it.

The alternative is to change the pot to a resistor - detail in the new thread - when I can it together!

Alan

Thanks Alan. I will try that this weekend.

sondale · « **Reply #134 on:** 18 Mar 2010, 09:46 am »

Quote from: sondale on 17 Mar 2010, 08:06 pm

Please note that I have started a new thread 'Optocoupled Attenuator Build' in which I will try to answer the various questions relating the much mentioned LSA.

Alan

I have asked that this thread be deleted whilst I am trying to resolve some (non-technical) issues.

earplay · « **Reply #135 on:** 24 Mar 2010, 08:06 pm »

So, can I hook up in series a 12v SLAB and a 6v SLAB to use as a 18v source?

sondale · « **Reply #136 on:** 24 Mar 2010, 08:12 pm »

Quote from: earplay on 24 Mar 2010, 08:06 pm

So, can I hook up in series a 12v SLAB and a 6v SLAB to use as a 18v source?

Yes, no problem with doing that.

Alan

earplay · « **Reply #137 on:** 24 Mar 2010, 09:22 pm »

OOOPS! That's bad!

The resistor at C2, the big one adjacent the power input, just blew smoke when I powered the unit. Is that resistor polarized?

wushuliu · « **Reply #138 on:** 24 Mar 2010, 09:41 pm »

Quote from: earplay on 24 Mar 2010, 09:22 pm

OOOPS! That's bad!

The resistor at C2, the big one adjacent the power input, just blew smoke when I powered the unit. Is that resistor polarized?

?

C should stand for capacitor. What board are you using ebay or Pass?

earplay · « **Reply #139 on:** 24 Mar 2010, 09:46 pm »

Well, maybe it is a capacitor, but it looks like a resistor to me. It's color coded like a resistor.

I'm using the ebay kit. There is no other component that fits the layout. I'm dizzled!