Review: Pass B1 Buffered Preamplifier

[ddk]

Have you tried Lundahl problem solvers? They make larger better transformers but I haven't seen them in a product just for conversion. It wouldn't be cheap as they cost more than Jensen by a good bit.

No, the Jensen's work as advertised for my purposes and their phono SUTs are one of the best kept secrets of high-end audio, great sound and real world pricing.

david

 

[Al M.]

Al M,

Can you tell us more details about what is exactly the DC-coupled 2015 version ? As far as I remember there was the original Pass designed capacitor coupled B1 and then a modification carried by DIY people, the DCB1. I would love to have more details on your 2015 Pass version.

A picture of the inside of your unit would be greatly welcome!

Hi Micro,

here is from the manual:

The circuitry is now DC coupled, removing two coupling capacitors in the signal path.

The DC offset value for the output voltage is less than 1 mV, and it will pass a DC signal as well as audio signal. The output impedance has ben reduced to 125 Ohms, and the distortion has been reduced at all frequencies.

The supply voltages have been increased and the supply noise had greater filtering for lower noise.

There is also a schematic, but it might take me a few days before being able to upload a picture. My connectivity is somewhat from the stone age

 

[Al M.]

By the way, you can always contact Nelson Pass by email, his address is on the First Watt website,

http://www.firstwatt.com/

 

[microstrip]

Hi Micro,

here is from the manual:



There is also a schematic, but it might take me a few days before being able to upload a picture. My connectivity is somewhat from the stone age

Thanks - the manual and schematic on the site http://www.firstwatt.com/ is still that of the old capacitor coupled B1. I will wait for your pictures and schematic.

 

[microstrip]

I have built units using Lundhal and Jensen top transformers and, long ago, one using the transformers taken from my old Sony XA-7. I use them just to mix SE and XLR units. They all sound very different and none of them approaches the sound quality of the SMC Flex Connect unit. http://smcaudio.com/products/flex-connect/. Curiously this unit is the worst measuring in terms of distortion of the four!

 

[Al M.]

Thanks - the manual and schematic on the site http://www.firstwatt.com/ is still that of the old capacitor coupled B1. I will wait for your pictures and schematic.

I am afraid I can't send you pictures because the unit is on loan to someone else Also, for some reason my hex keys don't work on the unit, it may be a metric format rather than inch derived.

I'll work on the schematic.

 

[microstrip]

No, the Jensen's work as advertised for my purposes and their phono SUTs are one of the best kept secrets of high-end audio, great sound and real world pricing.

david

David,

Do you prefer the JT436 or the JT437? The 6800 ohm loading requirement is not an issue in my case.

 

[Al M.]

Hi Micro,

here is the requested schematic: