Multichannel Mezmerize B1 or Pass B1 - diyAudio
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Old 5th August 2015, 02:33 AM   #1
ORNJ is offline ORNJ  United States
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Default Multichannel Mezmerize B1 or Pass B1

Hey all,

I am wanting to make a B1 into a Multi channel solution similar to the Parasound P7.

My question though, is how do I go about this? Can I take the board that is offered on diyaudio store and modify it or do I need to look more into an all new board? Or is it way more complicated than that?

My dream machine would be 9.1 input for the "Home Theater" input...9 channels just in case I ever go to Atmos/DTS X and get an Oppo that has that many outputs...not made yet but I figure it's only a matter of time.

And 2x two channel inputs for my turntable and maybe a DAC hooked up to a PC.

I think it would also be nice to modify this circuit to have a ".1" output for the sub since I am in a small place I can't do anything to give me bass like nice big floor standing speakers.

It may even be nice to have a zone 2 output if possible but this may be making too complicated.

I am leaning on going this route as MiniDSP has their Dirac room correction box now that you insert between preamp and amp so there is no need for an AVR anymore. Honestly, I don't usually use the built in EQ anyways as I don't care for the results. They are just different...not better....some areas are improved while others are worse.

I also think that it would be nice to have some gain/balance adjustment but I think that might be better on some DIY amps.

So what do you guys think? In a nutshell I am looking for a passive home theater preamp with a Light Speed Attentuator.

I have never taken on such a big project but I figure if I get the right help from someone I could wind up with something that may work out great for what I am wanting.
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Old 5th August 2015, 03:32 PM   #2
AndrewT is offline AndrewT  Scotland
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The B1 and the DCB1 are both 2 channel Buffers.
The B1 has a switchable choice of two 2 channel inputs.
The Mezmerise has a relay selected choice of six 2 channel inputs.

If you wanted to Buffer the output of a 2.1 you would need 3 channels, for a 5.1 you need 6 channels and for 7.1 you need 8channels.

6, 8 or 10channels of LED/LDR seems too unwieldy to be sensible.
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Old 6th August 2015, 02:16 AM   #3
ORNJ is offline ORNJ  United States
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Yep, I know the B1 is just two channel. But it would be n ice to take such a simple circuit and add more channels to it for my purposes.

I undersstand your point about the 8 channels for 7.1 etc. That is exactly what I was expecting. However, I don't understand your point about the LED/LDR, that's just the attentuator, why would that make such a stability problem?
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Old 6th August 2015, 07:49 AM   #4
AndrewT is offline AndrewT  Scotland
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a 2channel LED/LDR needs to be set up to "balance" the two channels.

Trying to do this "balance" for 6, 8 or 10 channels might prove to be impossible.
I never mentioned "stability" !

It is hard enough just getting good balance from a 6track vol pot.
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Old 6th August 2015, 02:44 PM   #5
BigE is offline BigE  Canada
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Quote:
Originally Posted by AndrewT View Post
a 2channel LED/LDR needs to be set up to "balance" the two channels.
Is there a schematic somewhere for this?
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Old 6th August 2015, 04:51 PM   #6
AndrewT is offline AndrewT  Scotland
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Yes, George shows it in his Thread.
It is also shown in the other LED/LDR circuits where the designer has decided not to keep the IP secret.
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Old 6th August 2015, 10:28 PM   #7
ORNJ is offline ORNJ  United States
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AndrewT, you seem to know a lot about LDRs.

What would you say would be better to use with so many channels?

Even though I would like the LDR, since I have been hearing such great things about it, I don't see any issue with giving it up in order to have a completely passive line stage that can be used for not only 2 channel but also Home Theater uses.
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Old 7th August 2015, 09:03 AM   #8
AndrewT is offline AndrewT  Scotland
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a ganged 6way vol pot can control the volume of a 5.1 system.
I have not come across an 8way or 10way.

That leads me to guess that different control system is the way to go.
eg. a relay attenuator with switchable volume settings. the relays are controlled by a single multi-way switch or controlled with software.
Alternatively a software controlled volume attenuator could work.

There is a newish LED/LDR using digital chips to measure and match the outputs of the two channels. I suspect this could be extended to many channels. Ask the designer if it can be extended and for a time budget and price budget. He has been working on it and reporting on progress for the past year.
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Old 9th August 2015, 03:19 AM   #9
ORNJ is offline ORNJ  United States
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link?
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Old 11th August 2015, 12:04 AM   #10
ORNJ is offline ORNJ  United States
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What about implementing something like this to control the LDRs?

http://www.dact.com/8-channel_passive_preamp.pdf

Or even just using the DACT instead of an LDR? I am not sure about the sound quality of them but I have heard in the past that they are very good.
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