Grounded Grid Preamp

[ray bronk]

Hi mach1,

This sonic character is one that I'm trying to investigate. So what's wrong with the 12AU7 that Ysaudio is using? Prefferable to these tubes is a 6688, or a 10Y, according to the Brits that were on the forum.

Ray

 

[pchw]

Hi Fred,

I'm also considering this tube preamp. This is not a kit.

http://www.ys-audio.com/sp+.htm

This might just sound better than the GGP.

Ray

I think that's the one I auditioned before which means I still prefer GG. This is just my opinion, you shall treat that as grain of salt as you may have a different personal preference. I always value others opinions but only trust my ears what sounds good to me

 

[pchw]

Hi Ray,

12AX7 and 12AU7 are 2 different tubes. GG and Foreplay use 12AU7, whereas YS-audio's use 12AX7. Many members don't like the 12AU7 because of the non-linear characteristics. While that is the case, Bruce chose the operating point very carefully with the GG. If there is any, I certainly can't hear in my GG's. But then my ears are not of any authority by any means I have quite a few commercial and DIY tube pre's. They all sound different from each other. That's why I said I let my ears to decide what sounded good in previous post. After all, I just want to enjoy music and the experience of different presentation by various gears.

Since you will need someone to help building your preamp, I don't recommend to go with the uncommon tubes because that may require different level of skills and knowledge from the builder. You didn't mention what amplifier you would use. That can also be a deciding factor.

 

[ray bronk]

Hi Fred,

Well, here's the deal. Since I am blind, I don't have the wherewithall to see the schems for any of the kits out there.

YS-audio uses the 12AX7 tube. Probably would sub it with a 7551 tube. Sounds better.

Anywho here's the problem. I am using a Greg Ball SKA GD150D amp.

http://www.ska-audio.com

Now, he has a feedback circuit that likes to see certain impedances of preamps. Anything under 800 ohms. He does suggest other remedities if the preamp is over 800 Ohms.

So I saw an AES with 6SN7 for about 550 new without remote. It's output impedance is 560 Ohms. The GGP is 200 Ohms. The two preamps from Ys audio that I'm looking at are 600 Ohms. So ... that's where I'm at. I don't remember what the Bottlehead preamp output Impedance is. I think it is using a 6x4 rectifier. So there you have it.

I am presently using a TVC, which the impedance will vary all over the place depending where the volume knobs are placed.

Ray

 

[Cobra2]

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I am presently using a TVC, which the impedance will vary all over the place depending where the volume knobs are placed.

Ray

So a Chathode-follower/buffer after the TVC may be all you need...?

Arne K

 

[ray bronk]

Hi, Well, I thought of that. I think I'd rather get a good active preamp. Any of these preamp configurations mentioned in this thread have to be better than the TVC. If not, don't want to waste my time.

Ray