Buffer.

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Nick
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#16 Re: Buffer.

Post by Nick »

But, as I have other pre's it would be nice if they were capable of driving the MoFo's as well
I think you may be a little confused about the idea of "drive" The MoFo is a very easy load, so a passive will drive it perfectly well. What you are missing is gain, not drive (assuming we agree drive means the ability to work into a low impedance or reactive load). The MoFo has a voltage gain of just about 1. So if you need 1W RMS into your 8 ohm speakers, it will need to produce a output voltage of 2.82v RMS. So the MoFo will need a input voltage of 2.82v RMS. Assuming you have a CD as a source that will nominally produce a output voltage of 2v RMS, you will need to multiply the voltage to get to 1W out.

From that you can work out what gain you need or want. All the talk of "drive" is just confusing matters.
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Ray P
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#17 Re: Buffer.

Post by Ray P »

Hi Phil - wot Nick said!

As I pointed out, the general theme on the DIY Audio thread is for people to drive their MoFos with gain stages, with the amount of gain varying depending on their specific context.

If you want to demonstrate this empirically I could loan you my buffered passive - the one I built recently using the vintage BUF-03 devices - it has no voltage gain but provides current drive, which manifests itself as the sound having more weight and authority, (along with the ability to use longer cables should that be required).
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pre65
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#18 Re: Buffer.

Post by pre65 »

My Pre3 is OK with the MoFos. :D

The "noise" that Pre3 suffers from was evident on start up, but at the moment it's seemingly OK. :?
Life is what happens to you while you're busy making other plans. John Lennon

G-Popz THE easy listening connoisseur. (Philip)
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pre65
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#19 Re: Buffer.

Post by pre65 »

On re reading the Pre3 assembly instructions, I'd forgotten that the gain can be x6, or x12 depending how the transformers are wired.

At the moment it's x6, so there is the option to increase gain if necessary.
Life is what happens to you while you're busy making other plans. John Lennon

G-Popz THE easy listening connoisseur. (Philip)
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rowuk
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#20 Re: Buffer.

Post by rowuk »

</Start pride of ownership post>
I use a Pass DIY B1 buffer as a preamp. It is not valve but is absolutely neutral (the highest compliment that I can give), has gain and has been part of my personal reference system for many years. The only modification that I made was bigger caps in the power supply.

Neutrality was tested by inserting it between my previous preamp and power amp for comparison. The reason that I wanted it was the much lower output impedance - to drive passive line level crossovers.
</End pride of ownership post>
:D
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