Mesmerize B1 vs Original Pass B1 - please guide me! - diyAudio
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Old 3rd September 2012, 05:54 PM   #1
KT is offline KT  United States
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Default Mesmerize B1 vs Original Pass B1 - please guide me!

Hi!

After being too busy for DIY audio for several years, I'm finally able to join you guys again. Yippee!

I wanted to pick up with some projects I was planning to build back then. First up is the Pass Labs B1.

When I checked the Pass forum after a long absence, I noticed that there is now a symmetrical version of the B1 called the Mesmerize. I went ahead and ordered a board from the store.

The Mesmerize can be run direct coupled, so no caps in the signal path. I like that idea, but I also know I like the sound of certain caps in certain circuits. Ei., the VTV Ultratones and various Audio Note and Jensen oil caps in my tube preamp and amps. So I'm not adverse to using caps as long as they sound nice to my ears.

Direct coupling removes those caps from the signal path so the signal is cleaner.

So in real life practice, and after many have had a chance to build and compare both, which one sounds better and why? Is there a clear winner, or are they both good? And is it just a matter of choice?

I'm wondering which one I should start building. Both seem great, but what are the differences in sound?

Thanks!
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Old 3rd September 2012, 06:55 PM   #2
tinitus is offline tinitus  Europe
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..... but I also know I like the sound of certain caps in certain circuits.
sounds like you might prefer the B1
I say 'might', because I havent heard any of them
hey, noones stopping you from putting a cap in the 'mez' too

but 'no cap' might be somewhat misunderstood
you will have to make sure there is no DC in the signal, so the cap may have be in there, somewhere, anyway
but that not the real big deal with 'the mez'
its more the shunt regulated power supply
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Old 3rd September 2012, 07:05 PM   #3
AndrewT is offline AndrewT  Scotland
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Put the cap in the Power Amp. That makes it compatible with any Pre-Amp/Buffer.
You can be clever and have a second input on the Power Amp that bypasses the input cap leaving just the RF filter.
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Old 6th September 2012, 01:40 AM   #4
KT is offline KT  United States
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Yes, I suppose if I want that oil cap "flavor" I could always put some in the mez. So maybe the Mesmerize board will be more flexible for my needs.

Does anyone have any strong preference for one circuit over the other? I'd find it helpful to know your impressions of how one sounds vs. the other. Based on your personal listening and comparison of both.

From what I understand, the original design from Nelson sounds very, very good. I can see, however, how a circuit that removes the caps can result in more transparency and neutrality. But it is also a different circuit, with its own electrical characteristics.

In the final analysis does the Mez circuit succeed in achieving the added transparency and neutrality while keeping all the good characteristics of Nelson's original design? Or does the Mez circuitry introduce its own flavor that may or may not be preferable?

Just wondering what folks think of each of these different designs once it playing music in their setups.

Thanks!

Last edited by KT; 6th September 2012 at 01:51 AM.
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Old 6th September 2012, 08:26 AM   #5
AndrewT is offline AndrewT  Scotland
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I can see, however, how a circuit that removes the caps can result in more transparency and neutrality. But it is also a different circuit, with its own electrical characteristics.
The DCB1 and the B1 are not different circuits. Both have a source follower device and both have a CCS load device. Both work identically in that the source follower is biased at Idss.

The only difference between the two is that the B1 must be AC coupled on both the input and the output, whereas the DCB1 can optionally have or not have AC coupling on either the input or the output.
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Old 6th September 2012, 04:51 PM   #6
KT is offline KT  United States
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The DCB1 and the B1 are not different circuits.
Thanks, Andrew. I was pretty sure the basic circuit was the same, yes.

What I'm curious about is whether the electrical scheme that allow the caps to be removed adds any of its own sonic artifacts, good or bad.

Just curious as to how each implementation sounds, generally. And how each may differ from the other sonically.

I'll most likely build up the Mez and go with that. I like that it gives the flexibility to add oil or other signal caps if one prefers that flavor.
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Old 6th September 2012, 05:13 PM   #7
tinitus is offline tinitus  Europe
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there is one important difference beteen the two
I think one uses the complementary jfet pair, and the other k170 only
k170 might be easier to find
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Old 6th September 2012, 05:23 PM   #8
Salas is offline Salas  Greece
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No, both are non symmetric n junction only.
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Old 6th September 2012, 05:40 PM   #9
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you even need no PCB at all if you have a +9/15V and a -9/15V regulated supply . with just 4 JFEt, and 6 resistor.
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Old 6th September 2012, 05:57 PM   #10
tinitus is offline tinitus  Europe
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No, both are non symmetric n junction only.
ups, sorry, I remembered wrong
I guess thats good then
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