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CSP2 Tube questions (Read 2536 times)
Ex Member

CSP2 Tube questions
07/18/07 at 08:12:22
This unit is supplied with 3x 6922-type tubes and a rectifier.
1.  What is/are the functions of the 6922 tube/s?
2.  Why 3?
3.  If these tubes perform different functions in the circuit, would it not be better to use different tubes depending on their function?
4.  There are a lot of other small triode amplifiers that use this pin set, why was the 6922 selected?
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Posts: 21
Re: CSP2 Tube questions
Reply #1 - 07/18/07 at 11:19:39
From the owners manual:

The CSP2 uses a single 6N1P/6DJ8, or 6922 (which is a dual
triode) to drive both the left and right channels.
This tube is located at the front just behind the
volume control. Changing this tube will change
the sound of both channels. Because of this, it
is arguably the most popular tube to roll if you
enjoy hearing how one brand of tube sounds
different from the next.
The two other 6N1P/6DJ8, or 6922ís which are being driven by
the front input tube, are wired one tube for
each channel. The left tube for the left channel,
right tube for the right channel. These can also
be rolled with different brands and have an
equal effect on how your CSP2 sounds. Just remember
that whatever you do on the left side,
you should also do on the right - meaning the
tubes should be of the same type and brand.

To answer your 3rd question, the answer is not necessarily especially in a pre-amp where the voltages are lower, but most power amplifiers will have different type tubes for each function. I own a different pre-amp that costs more than the CSP 2 where there are two input tubes (one per channel) two output tubes that are different than the input tubes (one per channel) and two rectifier tubes (one per channel) and CSP 2 blows it away period! Grin

To answer your 4th question Iím sure the answer is that those are the tube type that works best within the electrical parameters needed to build the unit. If Iím wrong Iím sure someone more knowledgeable will correct me.
Congrats on the purchase of a very fine product indeed.8-)
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Ex Member

Re: CSP2 Tube questions
Reply #2 - 07/18/07 at 14:01:33
Take a look at the articles tab on the website. There is a paper on the CSP2. I also am quite sure Steve D. would answer those questions if you gave him a call Wink
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Ex Member

Re: CSP2 Tube questions
Reply #3 - 07/18/07 at 16:16:58
I haven't bought it yet.  I am trying to understand it.  I own a Singelpower MPX3 Slam SE (OTL/SE) and a MAD Ear+ (Transformer coupled ouput stage).   I am looking at this amp because it can also be used as a preamp.  So, I wonder how good it is at preamping?

Quiet.  Low distortion (for tubes)?

The question I am getting to is: does anyone roll other tube types (not just brands) into these positions?  For example, could one use 6CG7s as output tubes?  The Singlepower I have takes a multitude of tube types and there are 3-4 socket adapters that expand the number of combinations a lot more.

Frankly i am not familiar with tubes that use this pin set, although they can be used in the SP.

I'm just wondering how adventurous people can get with this amp in tube rolling.

Actually since I have small fortune already invested in tubes for other preamps, headamps, and power amps, I am not sure how adventurous I want to be.

I am located near Copenhagen.
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Posts: 12608
Re: CSP2 Tube questions
Reply #4 - 07/18/07 at 17:29:27
Hi! I had a CSP2 built without a headphone output for the sole intention of using as a preamp.

This is the very best preamp I have ever heard in a system of my own.  It is astonishingly quiet, dynamic and exciting to listen to.

As for swapping out tubes. . . I think without going in and modifying the amp's "circuitry" you can really only use those three tube types mentioned and one other that is a 6N1P with much more gain (can't remember the name right now. . .6N2P maybe?)  These type of tubes are fairly common as preamp or input driver tubes. . . and they work very very well in this preamp/headphone amp, you won't need to roll other types.
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