2. amps-preamps
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Need suggestion on VTL TL-5.5 tubes

I've been using TL-5.5 preamp and I like it a lot. Recently I'm trying a different amp, which has much higher gain than the current amp, and noticed I'm hearing a lot of background noise now. The source of the background noise turned out to be my preamp. With preamp off, or out of the chain, there is no noise. My speakers are 93dB efficient, and the new amp has about 25dB of gain. The background noise is loud enough it's heard/felt at the listening seat at 8 ft away. It's clearly heard about 1 ft away from the speakers.

I really like my preamp and I'd like to keep it if possible, but I must eliminate the noise. I'm not sure if the noise is due to aging tube or other part of the component, or simply noisier nature of tube gear. My questions are:

Are there other TL-5.5 users with sensitive speakers that can comment on how much noise they are hearing? It's also dependent on the gain of the amp, as with my previous amp with 15dB of gain I don't hear ANY noise even when ear pressed against the tweeter, maybe except for slight hint of hiss.

Should I try new set of tubes? If so, any recommendation on 12AX7 and 12AT7 with very low noise floor?

Third question, somewhat tangential to the issue is the need to reduce overall gain. The useful range of volume knob is now from 0 to 10 o'clock. It needs fine adjustment by hand and it's not feasible to use remote control any more. Is it possible to reduce the gain on the preamp with a different set of tubes?
jylee
armstrod
609 posts
 
Jylee,

You should also be aware that not every preamp circuit will really change total gain by switching tubes. My Jolida Music Envoy barely changes gain at all when I switch from 12AX7s to 5751s. I generally like the sonics of the 5751s better, but the preamp gain stays roughly the same. No experience with the VTL, so not sure what would happen there. It's always worth a try; like me, you may like the 5751s better regardless of the gain.

David
tpsonic
1,092 posts
 
Find a tube vendor who grades the tubes:line/phono/MC phono.I suggest contacting Vintage Tube Services/Andy Bauman.Have had excellent results using his phono-grade miniture triodes (12ax/au/at).
jylee OP
306 posts
 
Thanks all for the suggestions. Looks like I have some shopping to do.
cheesehead
16 posts
 
I just received my 5.5 back from VTL with the V3 upgrade, and with it was a new set of o.e.m. tubes (jj tesla).
I let her burn for about 100 hours and then pulled the tubes, put in a nos set of RCA gray plates, which I prefer sonically, but was suprised to hear how much quieter they are. The back ground was nice and black with either set, but the RCA's can't be heard @ 1 foot away through my signature 185 mono's and 102db speaks.
jylee OP
306 posts
 
Cheesehead, did you replace the tubes with the same types, or have you tried different type of tubes in 5.5? I've ordered a pair of NOS JAN Philips 5751 and two pairs of EH 17AY7 hoping to reduce the gain on the preamp. If that works out well I'll try higher quality tubes.
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