Preamp choices for the tube amps

nooshinjohn · Post by **nooshinjohn** » Mon Jul 23, 2012 3:59 pm

I am loving the power and performance of my tube amps so far, but when I am using my Sunfire Tube Pre, all of the detail I have come to expect has completely vanished from the top end. The recording may as well no have cymbals, or other elements of a high frequency nature at all. When I am using my Pioneer SC37 as a pre, they sound spectacular, but I am also using the MCACC setup program as well. Is it that my room just flat out sucks (13x15 with the big Maggies 5ft apart) or that I should be looking for better tubes in the pre? Perhaps I need solid state for the pre instead?

Any suggestions on this guys?

Snoop65 · Post by **Snoop65** » Mon Jul 23, 2012 4:04 pm

It might be time for some new tubes. My prefered tubes are Amperex PQ 6922 white labels, Siemens Cca 6922, and Amperex orange globe 6DJ8's.

angelod307 · Post by **angelod307** » Mon Jul 23, 2012 5:01 pm

no issue like that for me. the tube amp sounds incrediable with my pre. it sounds more open than the tfm55 going to my carverfest speakers. it is very good i say. wish i could hear your setup on the maggies and then compare notes.

nooshinjohn · Post by **nooshinjohn** » Mon Jul 23, 2012 5:36 pm

The amps sound fantastic when run through the Pioneer, but lack any sparkle at all when played with the Sunfire. The initial tap on a cymbal, and the resulting decay are completley missing, and my Maggies have a 6 foot tall ribon in them! verything else apppears to be good from the bottom up through the mids.

I am going with some Bugle Boy 12AT7's and Telefunken smooth plate halo getter 12AX7's and see what this does for the amps. hopefully this wakes up the upper end. If it does, then I will be putting the Sunfire back in the mix.

TNRabbit · Post by **TNRabbit** » Mon Jul 23, 2012 6:00 pm

Sounds like there's a problem somewhere. Are you using the same interconnects with the pioneer and sunfire? Perhaps There is some kind of Impedance mismatch...

Snoop65 · Post by **Snoop65** » Mon Jul 23, 2012 6:06 pm

nooshinjohn wrote:The amps sound fantastic when run through the Pioneer, but lack any sparkle at all when played with the Sunfire. The initial tap on a cymbal, and the resulting decay are completley missing, and my Maggies have a 6 foot tall ribon in them! verything else apppears to be good from the bottom up through the mids.

I am going with some Bugle Boy 12AT7's and Telefunken smooth plate halo getter 12AX7's and see what this does for the amps. hopefully this wakes up the upper end. If it does, then I will be putting the Sunfire back in the mix.

Are you just playing records because 12AX7 are used in the moving magnet section of the phonostage. If you are playing Cd's you will need to change the 6DJ8/6922 tubes in the line section too.

Snoop65 · Post by **Snoop65** » Mon Jul 23, 2012 6:07 pm

TNRabbit wrote:Sounds like there's a problem somewhere. Are you using the same interconnects with the pioneer and sunfire? Perhaps There is some kind of Impedance mismatch...

Good point.

nooshinjohn · Post by **nooshinjohn** » Mon Jul 23, 2012 6:18 pm

The tubes I have ordered are going into the amplifiers themselves, and I will check it again. I spin mostly vinyl, but CD's are an option. If I am going to crack the case on it, I am going to replace the broken contour controls and replace all the tubes at the same time. The combination of the Pioneer and the tube amps sounds phenomenal on teh big Maggies, but the Sunfire Pre everything sounds as of sumebody stuffed cotton in my ears... heavily veiled. Bob was using a Carver C 4000 for his pre when I was there, and had everything hooked through an EQ and a spectrun analyzer.

Snoop65 · Post by **Snoop65** » Mon Jul 23, 2012 7:00 pm

The Telefunken smooth plates should make you REAL happy. I have a set but my preferred tube is the GE black plate triple mica 5751 by a small margin. Just got some Sylvania black plate triple mica 5751's from a good friend and I think they will become my new standard.

MRHP · Post by **MRHP** » Mon Jul 23, 2012 9:48 pm

I had this exact problem with my Sunfire tube pre. The problem was that I had a set of F-Mod high pass filters running thru the second set of outputs for my subs. Do you have anything hooked to the second set of outputs on the Sunfire pre? Or maybe some odd combo of IC's.

angelod307 · Post by **angelod307** » Mon Jul 23, 2012 9:57 pm

by far, the telefunkens sound awesome in the amps. way better than oem. now the 6bq5, leave them alone, there is no advantage in swapping them like the 12ax7. bob was amazed at the change in it all, as the engineer in says there should be no difference like that, yet it was night and day and brought a tear to his eye cause it sounded that awesome playing his symphony music on the new amazings with a c1 pre, 2020, and a hk cd player. we tried many 12ax7s that evening and all agreed that the tele's were the favorite tubes there. interestingly though, they were not as dramatic in the 305's, althought still very good.

Snoop65 · Post by **Snoop65** » Mon Jul 23, 2012 10:17 pm

Sunfire Classic tube pre+ NOS tubes =AWESOME!!!!!

stereo_buff · Post by **stereo_buff** » Tue Jul 24, 2012 2:04 pm

Did you say whether or not you were listening to vinyl when you noticed the 'lack of sparkle'? I noticed something similar when listening to LPs (using an MM cartridge) until I replaced the 5751 (12AX7) on the phono PCB of my Sunfire Tube Preamp. According to Bob, the circuitry requires every bit of gain available from the 12AX7 (the 5751 is a ruggedized 12AX7, but with slightly less gain, according to Bob; 30% less, according to Tube Depot), In addition, Bob told me that the frequency response on the bottom end was also slightly degraded when using the 5751 in the phono circuitry. Replaced with an Amperex 12AX7 and everything was cool.

Snoop65 · Post by **Snoop65** » Tue Jul 24, 2012 2:22 pm

stereo_buff wrote:Did you say whether or not you were listening to vinyl when you noticed the 'lack of sparkle'? I noticed something similar when listening to LPs (using an MM cartridge) until I replaced the 5751 (12AX7) on the phono PCB of my Sunfire Tube Preamp. According to Bob, the circuitry requires every bit of gain available from the 12AX7 (the 5751 is a ruggedized 12AX7, but with slightly less gain, according to Bob; 30% less, according to Tube Depot), In addition, Bob told me that the frequency response on the bottom end was also slightly degraded when using the 5751 in the phono circuitry. Replaced with an Amperex 12AX7 and everything was cool.

Which 5751's were you using?

stereo_buff · Post by **stereo_buff** » Tue Jul 24, 2012 2:36 pm

Snoop65 wrote:
stereo_buff wrote:Did you say whether or not you were listening to vinyl when you noticed the 'lack of sparkle'? I noticed something similar when listening to LPs (using an MM cartridge) until I replaced the 5751 (12AX7) on the phono PCB of my Sunfire Tube Preamp. According to Bob, the circuitry requires every bit of gain available from the 12AX7 (the 5751 is a ruggedized 12AX7, but with slightly less gain, according to Bob; 30% less, according to Tube Depot), In addition, Bob told me that the frequency response on the bottom end was also slightly degraded when using the 5751 in the phono circuitry. Replaced with an Amperex 12AX7 and everything was cool.
Which 5751's were you using?

RCA, 1974 manufacture, NOS

CarverAudio.com

Preamp choices for the tube amps

Preamp choices for the tube amps

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