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Is there such a thing??-- Tube Preamp Question

Hello All,

I have recently acquired my first tube preamp. Its a Blue Circle 21.1 with the stepped attenuator. From the start its been a journey. When I received it there was a distinct buzz/hum. I sent it out for repair and they found it was the power transformer. They made me a spiffy new external power supply which solved the problem. I truly love what it does for tonality, richness of voices and my sound stage appears deeper to me with good placement of instruments within it. However, and maybe my expectations are just to high, the hiss and tube replacements (needed to replace tubes after 6 months) along with a generally fussy nature in terms of the need to pop the top and clean to get the fuzzy sounds out occasionally just seems a bit much. Are all tube pres susceptible to this level of need an "fussy" temperament? Another issue, is when I am watching TV and/or using TV as a source, between songs there are strange sounds(bleeps and squeaks) and moments of scratchy sounds noted in quiet passages and seem triggered by moving from one song to the next. It seems very sensitive to picking up TV noise which I have never noted using solid state gear.  While it isn't evident at medium to high volume it just bothers me and I know that its there. 

Can I have all that this does for me in terms of tonality and sound stage along with a less fussy nature? Does such a thing exist for a reasonable price($1000-$2000). I would like a more silent background with less need for constant attention. 

Does such a thing exist?
128x128birdfan
elliottbnewcombjr
5,610 posts
 
I have 30 wpc tube monoblocks made in 1956. I still have two 35 wpc fisher 500c, 1 35 wpc fisher 800c, have had other tube stuff, and friends with tube stuff. I just bought an old McIntosh tuner/preamp from the 60's. One of these

https://www.ebay.com/itm/McIntosh-MX110z-Vintage-Tube-Preamplifier-FM-Tuner-Very-Good-Condition/264282601872?hash=item3d88787990:g:mAEAAOSwvcBch~My

Plugged it in, play: noiseless. Nice FM antenna, awesome radio. TT, fab sounding phono eq, ...

Just bought a tube amp, 22/45 wpc, NO NOISE.

Tube amps and tube preamps SHOULD NOT MAKE NOISE! If so, something is wrong. I would never mess around like you have. It's not your fault. Tube life is much longer than most people understand, typical power tubes rated for 10,000 hours. Smaller preamp-tuner tubes much longer than that. Military spec tubes have ridiculously long lives, your grandchildren will still be playing them, unless they read too much.


elliottbnewcombjr
5,610 posts
 
IF you are driving low sensitivity speakers with tubes, probably not enough power, you will get noise, then perhaps no sound!
bigkidz
3,404 posts
 
This sounds like tube issues if you are using old NOS tubes or tubes that are just no measuring good any longer. Also could be the tube sockets. You may want to clean the sockets and tube pins first.

Removing the transformer into a separate chassis was a good idea as it
isolates the transformer noise from the tubes.

If cleaning doe snot work, I can repair the unit or my suggestions would be:

1) Counterpoint SA-2000 or 3000 preamps. Send them to me and I will upgrade them and you will have a preamp that competes with almost anything out there.  The upgrades are volume control, Nichicon capacitors, Amtrans and Caddock resistors, and V-caps - read the review of the new V-Cap that just came out.  I also rewire some of the internal design to improve the sound. 

2) My friend purchase a Prima Luna 6922/6DJ8 tube preamp that I thought sounded very good for the money $2300?

If I can be of any help, send me a message through Agon.

Happy Listening.
birdfan's avatar
birdfan OP
175 posts
 
Thanks all for your feedback. Removing the tv removed the problem. I also am using the low gain setting on all the speakers except the Maggie’s. Cleaned the tube sockets and tube pins as well as everything in the preamp with deoxit. It’s dead quite now. Thanks for all the guidance!! 

@curiousjim  do you have a recommendation on which brand 7308’s to look into?
porscheracer
132 posts
 
The 7308’s are the  Cadillac of the 6DJ8‘s  tubes  and therefore are priced  accordingly.  They don’t last as long as the 6922’s but will sound the best of all the  6DJ8 line.

Where this incorrect information coming from? Brent Jesse??? If you actually listen to the tubes and to people that have, there are very few 7308 tubes that rank highly in the 6DJ8/6922 application. Especially compared to the CCa tubes from Siemens and Telefunken. 

But, I like using the Western Electric 396A/JW 2C51with a 5670 to 6922 adapter. That tube beats every 6922 variety I tried.
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