Pass B1

[shafic]

Hi shafic sir
It was my b1 which joshua got to your place.
I can confidently say after the resistor mods the bass, overall weight in the sound has improved quiet substantially along with very good details in the highs

Yes sir,

I knew it was your B1 i heard. I still remember the clean highs which surprised me. I am sure the resistor mods must have improved the bass section. I have also been following the threads on B1 mods. Would like to listen to the modded version some day.

regds,
shafic

 

[captrajesh]

@Dr. Bass, before sinking in your top dollars, why don't you borrow a fully made DIY preamp and see if it floats your boat? Unfortunately, you are in Singapore and shipping it back and forth would cost a bomb.

Just realised that the above post could be construed to be having negative connotations actually I didn't mean it that way. I have one and it is a fantastic performer. Having said that, I empathise with one poster who said it matched one amp superbly while was not so great sounding with the other because I did the same experimentation with Acoustic Portrait and Class D Audio SDA 254 Power amps. It matched the AP superbly while the performance was kind of mediocre with the Class D. The AP has an output impedance way higher than that of the Class D amp and that could be the reason.

I do not know about the implementation in the commercial preamp but in the DIY stuff, the signal goes straight to the pot, gets attenuated and goes into the buffer stage of the B1; so that may have something to do with this anomaly so to speak.

I have the B1 kit with lightspeed attenuator and r-core trafo lying around - I purchased from OMisra but don't plan to build it anymore. but its with one pcb.

You need a second one to put in front of the attenuator.

That is applicable only if you want the LSA in the circuit. I made one with SSP in front of the attenuator. Yet to test it though.

 

[Santy]

I have heard a few systems with Pass B1 and it was too good.
But the B1 that I built was not matching well with the Genelec monitors.
Vocals became kind of edgy and constricted. The sound appeared to be coming from very small drivers like in satellite speakers.
May be it was because of two preamps in the chain or a lack of synergy.
I eventually sold it off.

 

[sachu888]

B1 performs best with standalone power amp. It sometimes has a problem with few of the integrated amps. You can easily alter output impedance by swapping two 1k output resisters to as low as 100r.
Those big output caps especially Russian petps take very long approx 100 hrs to fully break in, so give enough time before reaching any conclusion.
I using B1 close to 3 years and it matches perfectly with my DIY Amp Camp.

Regards
Sachin

 

[sachu888]

I have the B1 kit with lightspeed attenuator and r-core trafo lying around - I purchased from OMisra but don't plan to build it anymore. but its with one pcb. You need a second one to put in front of the attenuator.

G0bble

You can use SSP to overcome this problem. It will provide you enough gain without colouring the sound with right opamp.
I am looking for another Light speed attenuator, let me know whenever you deside to sell.

Regards
Sachin

 

[rikhav]

B1 performs best with standalone power amp. It sometimes has a problem with few of the integrated amps. You can easily alter output impedance by swapping two 1k output resisters to as low as 100r.
Those big output caps especially Russian petps take very long approx 100 hrs to fully break in, so give enough time before reaching any conclusion.
I using B1 close to 3 years and it matches perfectly with my DIY Amp Camp.

Regards
Sachin

So basically what dr. Bass will need to do is that get resistors fitted from the factory itself so that output impedance is suitable to his power amp

Rather have a direct talk with guys at first watt / pass labs. I think they will have better idea what value they use in factory assembled b1s and is a change needed

 

[sachu888]

I think commercial Pass lab products are better. I am not sure though. I don't think he should worry about swapping resisters at very first stage.

Regards
Sachin

 

[dheerajin]

B1 performs best with standalone power amp. It sometimes has a problem with few of the integrated amps. You can easily alter output impedance by swapping two 1k output resisters to as low as 100r.
Those big output caps especially Russian petps take very long approx 100 hrs to fully break in, so give enough time before reaching any conclusion.
I using B1 close to 3 years and it matches perfectly with my DIY Amp Camp.

Regards
Sachin

Hi Sachin,

Yesterday I wrote my observation to Yamaha and they replied with answer what you and jai1611 are saying.
"this yamaha amp is degined on balance topology concept , so any other pre-amplifier will hardly do the justice with its power amp. In your developed pre amplifier, do some modification by resister change and see if it improves the sound."

So now it explains all, and guys, no need to conclude anything about Pass B1.
It is just matching of the components thats all.

Cheers

Dheeraj

 

[dheerajin]

I have the B1 kit with lightspeed attenuator and r-core trafo lying around - I purchased from OMisra but don't plan to build it anymore. but its with one pcb. You need a second one to put in front of the attenuator.

G0bble

Hi G0bble,

There are many takers for the Pass B1 in the forum. So please let us know when you are selling the kit.

Cheers

Dheeraj

 

[gobble]

You can use SSP to overcome this problem. It will provide you enough gain without colouring the sound with right opamp.
I am looking for another Light speed attenuator, let me know whenever you deside to sell.

Regards
Sachin

Ok. I've got a 3 month listening test to do with another speaker and see if I really want my current amplifier for life or if I will switch eventually. Because if I switch I may need a preamp. It may be a bit of a wait...

G0bble

 

[spirovious]

Hi,
I would like to know few details about B1 and SSP-
1.What is the minimum current required to run B1 and SSP? (voltage I know)
2.What is the minimum transformer requirement?(say 12-0-12V enough for smooth operation?)

I am just asking it as I found with another DIY device that changing power supply makes a certain sound improvement.Overkilled specifications of power(or other) can change or downgrade sound quality.So curious to know.

 

[omishra]

Hi,
I would like to know few details about B1 and SSP-
1.What is the minimum current required to run B1 and SSP? (voltage I know)
2.What is the minimum transformer requirement?(say 12-0-12V enough for smooth operation?)

I am just asking it as I found with another DIY device that changing power supply makes a certain sound improvement.Overkilled specifications of power(or other) can change or downgrade sound quality.So curious to know.

B1 -> 18-24V, 20mA
DCB1 (my PCB) -> +10,-10; 18mA

SSP -> ~25mA-40mA (OPAMP biased default)

12-0-12 is okay with SSP, DCB1
18-0-18 is optimal for B1.

 

[manniraj]

I did the polish for the face plate of the B1 cabinet couple of months back. I used the oil used for cricket bats applied 4 to 5 quotes and sanded. Then couple of quotes of sheenlac for the shiny finish. Hopefully it looks good. Here are the pictures taken from my mobile camera.

 

[kaushik]

need to learn a lot from you on finish

 

[manniraj]

need to learn a lot from you on finish

Thanks kaushik, its the forum and its knowledgeable members from whom I have learned the simple techniques of DIY and enjoy replicating the same :clapping:

 

[keith_correa]

Then couple of quotes of sheenlac for the shiny finish.

What is sheenlac?

 

[manniraj]

What is sheenlac?

Its a brand name and I believe its a liquid form of shellac mixed with alcohol, but not sure. Let me Google more on it.

 

[sarith]

What is sheenlac?

Paint Companies in india, Home Colour Painting, paint - sheenlac paints

 

[keith_correa]

Paint Companies in india, Home Colour Painting, paint - sheenlac paints

I'd already seen that and it does not help any. It's like saying "I used Nerolac".

 

[manniraj]

I'd already seen that and it does not help any. It's like saying "I used Nerolac".

As I quoted in my earlier post its a plain transparent liquid in which you can mix color as per your choice. If you have seen my post in the Frugal horn thread on the polish, my carpenter had used a "Torquise" chalk powder and mixed with the sheenlac to get the matching finish as per my furniture.