2. amps-preamps
  3. 1366645727

Tubes in VTL Deluxe Preamp

I have a VTL deluxe preamp, purchasing it from an authorized dealer in the late 1990's, it was purported to be a demo unit.

Whats a bit odd in comparing the various related threads, is that the unit has 6 tubes. It is fitted with 3 - 12AX7 and 3 - 12AT7's. All of the other threads convey a different mix. The split, looking at the unit from the front - on the side of the circuit board facing front, is 3 - 12AX7, then 2 12AT7's, and then on the other side of the board, a 3rd 12AT7 on the far left, again looking at the unit from the front.

Is this the correct mix/order?

The volume level of the system is slowly decreasing, there are 2 VTL-MB250 amps which have recently been retubed, so I suspect its the preamp tubes that may be needed replacement.

The unit currently has TungSol 12AX7's, and Jan Phillips for the 12AT7's. I have seen other types available, to inlcude mullard. While I dont want to go nuts, I would rather retube this so that it actually provides improvements. The amps hook up to Martin Logan Request speakers.

Thanks
Ron
128x128alphlulu2
tls49's avatar
tls49
1,351 posts
 
Ron, your thread caught my interest because I have a VTL Maximal preamp from the same era stuffed away in a closet. I would also be concerned about the correct mix/order of tubes. To start with, Audiogon Bluebook states manufacturing date as late 1980’s, and you purchase as a dealer demo in the late 1990’s.

Looks like units with M/M phono had 5 tubes and with M/C phono had 6 tubes. Check out the links below, and look at the serial number plates on each.

http://www.ebay.com/itm/VTL-Tube-preamplifier-Hand-Built-with-Phono-input-NO-RESERVE-AUCTION-/121096825950?pt=Vintage_Electronics_R2&hash=item1c31eeec5e

On this unit at ebay, it’s easy to see the 3 tubes closest to the power supply (left side in picture) are 12AT7’s. The other 2 appear to be either a 12AX7 or 12AU7.

http://www.canuckaudiomart.com/details/43224-vtl_deluxe_preamp_with_optional_builtin_tube_mc_stage

On this unit at Canuck Audio Mart, I can’t tell about the tubes from the picture, but the description says it uses 3 - 12AX7’s, 2 - 12AU7’s, and 1 – 12AT7 (6201).

I did also find one that had 6922’s, but it had been modified for them.

If you haven’t already, it’s probably going to be a good idea to post in some other audio forums on the net.
alphlulu2's avatar
alphlulu2 OP
2 posts
 
Very interesting, I did check the tag on the back, Model - Deluxe M/C, Serial AD3202M/C. Your right that the MC has 6 tubes, and I confirmed that the first 3 in the ebay unit, and the one I have are the 12AT7's.

The other listing indicates 3 12AX7's.

I have never used the MC output, do you know what it stands for and how its used?

Thanks

Ron
tls49's avatar
tls49
1,351 posts
 
I have never used the MC output, do you know what it stands for and how its used?
Is yours labeled MC output?

M/C generally means moving coil phono which should be an input.
More to discover