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

Showing 3 responses by jylee

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.
I've spent last couple of months tube rolling. I just replaced the 12AX7 input tubes and left 12AT7 alone. I tried the following.

JAN 5751
Telefunken 12AX7 ribbed plates
RCA 12AX7 Wurlitzer branded
Philips Miniwatt 12AX7

RCA tubes are remarkable. It's must more quieter than any of the tubes I've tried. The tonal balance is more on the neutral side. It's not as tubey or mellow as others, but crispier and cleaner. There is still plenty of midrange bloom, and the tubed sound is unmistakable. Very happy with the result, especially the lowered noise floor.