Sorry, input
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
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
4 responses Add your response
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 |
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 1980s, and you purchase as a dealer demo in the late 1990s. 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, its easy to see the 3 tubes closest to the power supply (left side in picture) are 12AT7s. 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 cant tell about the tubes from the picture, but the description says it uses 3 - 12AX7s, 2 - 12AU7s, and 1 12AT7 (6201). I did also find one that had 6922s, but it had been modified for them. If you havent already, its probably going to be a good idea to post in some other audio forums on the net. |