B1 builders thread

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I'm driving an Aleph 4 which sounds perfect with nothing in the signal chain..

At the input is an Arcam CD36.. again transparent.

Both have a sonic signature. The Aleph especially. But i think you are right that these are quality components. What was your pre?

Caps it is then.

I would get Obbligatos over the Mundorf you showed. Solen is another good choice at reasonable cost

Why do some guys recommend massive transformers, and others regulators ?

You say Tomato, I say Tomato.
 
I did have a Pumpkin Pre before but it was faulty. Some guys have been saying that the fault may well have coloured the sound - brightened it up even.

The CD36 playing directly into the Aleph 4 is what I am after. I had a stepped ladder attenuator but it was too coarse and introduced problems of its own.
 
I believe those bypass caps are used specifically for HF performance. The obbligatos wold cost you about $20 shipped. The Solens would be about $15 shipped from PartsExpress. You may see improvement with Mundorf. Wait and see and decide then. I chose DCB1 so caps were not a problem. Top end is not a problem with mine at all and i have very critical speakers.
 
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The B1 sounds great running off a pair of standard 9v batteries in series... I ran mine that way to test it. It ran for hours... I lost track of how many. I now use a wall wart supply (Panasonic phone) I had in my tool box. It tested smooth and stable so I thought I'd try it. It supplies 100ma. Sounds great.
 
Are these what you are talking about ?

They don't do 10uF, only 6.8uF or 15uF at £18 GBP each.

15uF should do the trick I think.
 

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Are these what you are talking about ?

They don't do 10uF, only 6.8uF or 15uF at £18 GBP each.

15uF should do the trick I think.

Here is what I am using at the output of the BA3.

http://www.partsconnexion.com/capacitor_film_obbligato_oil.html

To brighten things up, maybe the ones you picture will work. I haven't tried them. Solen MKP are cheap and easy to obtain. Oil ones i showed may be taking you in the wrong direction. I the Mark Audio Alpair A7.3 drivers and top end is plentiful. I find myself wanting to smooth it over sometimes. Using the Alpair 10.2, which is smoother, different story. End of the day, B1 may not work. Too bad your not in the states or i would send you my DCB1. I am about to do a dual mono version and will have the SE sitting around while I listen.
 

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OK I've gone for the Obliggato 10uF Paper in Oils.

BOY. They are HUGE. 95mm long and 40mm Dia.

This is going to be fun trying to get them to fit.

There is space but I'm going to have to raise them off the board to clear the other components.

This is going to be mini re-build.

The transformer is being replaced by a 30VA toroid. I'm going to replace the capacitive multiplier with a CRC circuit and the output caps are being replaced with the coke cans. The outline of the PIOs is shown highlighted in PINK.

I'm wondering wether to retain the regulator or just let the B1 run with a good CRC filter. Its 4700uF + 1R0 + 4700uF. More than sufficient for the B1.

I originally didn't have the regulator, it doesn't seem to have made much difference.
 

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I've just received the Chinese Audiophile caps from E-Bay.

On inspection they are very small compared with the 1uF WIMA MKS4 caps that I'm currently using.

(Yes I know the value in the photo is wrong - it's a stock photo)

Looking at the original Pass B1, the input caps are simple blue dots.

I'm still going for the Obligatto 10uF PIOs for the outputs, but has anyone any experience of these Audiophile (Yellow Caps) compared to the MKS4's as input caps ?

I've got some 3.3uF 750V WIMA MKP4's that I could use as input caps but they are much bigger than the MKS4's that the board was designed for.
 

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You shure do ask a lot of questions considering your experience. From what littl ei know of Mr Pass, he tends to place his emphasis on the active devices and the topology more so thatn the individual components. This is not to say he doesn't have preferences, but realizes that each person has his or her own opinions and tastes. Most of his schematics leave great freedom in part selection based upon personal opinions. Both caps are in the signal path, so they both have an affect. The only way you are going to know is to try. Search the forum for preferences in your price range and swing away.
 
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