Forums - Tube recommendations for CSP3 and Rachel

thevinoman

Senior Member

Posts: 81

Tube recommendations for CSP3 and Rachel
Yesterday at 22:05:16

I just acquired an excellent CSP3 with Miflex caps (2022 build) from a very nice gentleman to go along with my 34i.5 Rachel. In the CSP I have 3 6N1P in all the slots and a very nice USAF RCA 5U4G. However, I'm thinking it's a tiny bit thin on the bass (I'm running Klipsch Industrial La Scalas, and Klipsch KPT-904s) . It might just be me, but I'm wondering if another tube combo would boost the low end a little. This is the first experience I have with the CSP, so I'm looking forward to the experts' advice here. Thanks very much.

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will

Seasoned Member

Posts: 3151

Re: Tube recommendations for CSP3 and Rachel
Reply #1 - Yesterday at 22:59:44

Fun! The first thing I would do if you have not already, is not consider the CSP3 as a preamp, but instead as a sound shaper. It has such a wide range of voltage output, you can do a lot to tune your overall sound with just the individual tube pots and the CSP3 gain.

I might suggest starting by setting the front right/left pots at 7, and the back ones at 8. Then, set the Rachel attenuator at whatever level you are used to for a satisfying volume for your room and tastes, and bring the CSP3 attenuator up to where it sounds about as loud as you were used to with just the Rachel. Then try "riding the gains" between the CSP3 and SE34 while keeping close to the same volume, to hear how the CSP3 voltage (and all the rest of it) adjusts the sound, when increasing CSP3 voltage, emboldening your sound, and reducing it in the blend likely opening and leaning the sound. This can be really useful for tuning to different recordings.

Toward your end of bringing up bass some... for example...if you liked your amp at half volume, maybe start setting it there without music, and the CSP3 turned down. Then with music, bring the CSP3 master gain up to fit that volume you liked in your room... Then, to amp up the signal, keeping the volume as close as possible to the same, turn the CSP3 up while riding the Rachel gain down at the same time.

This will give a good sense of how the increased voltage of the CSP3 can embolden the CSP3 and SE34 sound qualities, likely including bass, weight, lucidity, dynamics, space, etc, while introducing the fun of using the CSP3 as a sound refinement tool rather than a great sounding volume device.

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CAJames Seasoned Member "I've run every red light on memory lane." Posts: 3194	Re: Tube recommendations for CSP3 and Rachel Reply #2 - Today at 00:44:53 I don't have a CSP, but if you are looking for more low frequency in my experience the best small signal tube for the job would be a Mullard UK PCC88.
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Dominick

Seasoned Member

Still like that old
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Posts: 1534

Re: Tube recommendations for CSP3 and Rachel
Reply #3 - Today at 02:49:03

I was originally running three 6N1P Decware red tipped tubes in my fully modified CSP2+ and enjoyed the sound. Since I run a ZRock2 before the CSP, I am able correct the bass output. But I do know what you are saying about the bass being a bit thin when my ZRock is at unity gain. I would say the bass is not as punchy with less authority.

Anyway…I have recently switched the two rear tubes with some NOS 6SN7 RCA VT smoked glass tubes. As Will described the CSP as a sound shaper…I would say that these tubes make the bass present itself as warmer, holographic, with more authority. It’s not slow nor is it syrupy..it gives female vocals a more natural sound. That’s the good news. Now the bad…those tubes are not cheap and you need converter bases for them. And to top that off..the tube socket screws prevent the base converters from fully seating….so you may also need socket savers to help the converter bases clear the screws. Does that make sense? Hers a pic to give you a better visual. Hope this helps.

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will

Seasoned Member

Posts: 3151

Re: Tube recommendations for CSP3 and Rachel
Reply #4 - Today at 15:38:45

When I was using 6SN7s with Decware, I got several pretty nice 6SN7 to 6922 converters from a Chinese makers over time. One is similar to one I saw today on Amazon, made in what looks like a brass ring, with a ceramic tube socket and gold pins. I was careful, but it was pretty easy to use a Dremel tool to dig out some spaces on each side that were just big enough to accommodate the Decware screws that stick up from the plate.

I have not tried any for quite a long time so a little vague, but as I recall, Dom is making a good call, 6SN7s used in Steve's 9 pin settings tending to a little fuller bigger sound that might help in your setting. I did not have RCA VTs, and likely different sounding, but the early RCA black glass 6SN7s I had were pretty well resolved, but for me a little masked from being a little too dark flavored here, and a little soft lower down for my tastes.

Unfortunately, there are lots of the type, and in use by lots of folks, the popular ones are not cheap. All I have sound different, so a potential labyrinth. Here, though I always like things about them, they never seem to stay in a long time so far. At the same time, I have never felt my CSP3 was lean or lacking in bass either, though I have never fallen for 6N1Ps either and it has been so long since I have used them, I can't articulately recall exactly why they did not fit in for me. But many folks seem to like them, and many seem to really benefit from 6SN7s. If you don't have some around, and search, I recall there was a time when converting to 6SN7s was a big area of interest on this forum and you might gather some insights from others experiences in their systems that could help in your particular setting.

A tube I do use, mostly in my DAC, but also in the power position of the CSP3 a times, is a 6CG7, a 9 pin variation that does not need adapters but is supposed to be the same as 6SN7s electrically. I tend to prefer them in my settings over 6SN7s, to me 6SN7s tending to be a little forceful/dense in presentation, and preferring the, in general (here), more open/complex tending sound of the 6CG7s I have tried. There are quite a few out there that are pretty low cost comparatively to popular 6SN7s also, so less risk to experiment. These tubes have been discussed on this forum as well and may be worth looking at people's impressions on different ones.

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thevinoman Senior Member Posts: 81	Re: Tube recommendations for CSP3 and Rachel Reply #5 - Today at 16:58:33 Thank you to all who replied. Really appreciate it. Will, when you say the "power position", are you referring to the input tube on the CSP3? If so, what were you using for the output tubes? Thanks.
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thevinoman Senior Member Posts: 81	Re: Tube recommendations for CSP3 and Rachel Reply #6 - Today at 17:00:37 I think I also have to come to the realization that I'm not pushing very many watts, and of course compared to my McIntosh MC240 or Scott LK-150, it's not going to be the same.....
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