New (to me) D120 - power tube recommendations?

[jc986]

I bought a Deliverance 120 and it just arrived yesterday. I’m loving it so far. I’ve never played a single channel amp that is so versatile before. My serial number looks to be A070137, but it is a bit faded. Would that serial make this a 2007 production? It has the VHT badge.

The amp appears to still have the original Sovtek KT88’s installed as they have the VHT stickers on the bass of the tubes. Preamp tubes are all Ruby Chinese 7025SS 12AX7A except for V1 which is a Sovtek 12AX7WB and the 12AT7 which is also Ruby Chinese.

I have an assortment of preamp tubes on hand but don’t have any backup KT88’s. What are you guys using for power tubes these days? I have read the manual and see that Fryette recommends EH, Sovtek, or Svetlana. It seems that the Sovtek and Svetlana are difficult to find anywhere.

[metalhobo]

sovtek tubes are no longer in manufacture, unfortunately.

EH KT88s are alright but the two pairs I tried seemed to be short lived. could be bad luck.

my favorite so far have been gold lion KT88s, but they're not cheap.

also I recommend a tung sol 12ax7 in the V1 position

[jc986]

Cool. I have a couple Tung Sols on hand so I’ll pop one into V1. I was looking at the Gold Lions and was hoping someone had some experience with them. May order a set to see how they compare to the Sovteks. Are there any instructions on biasing the D120? I have a bias probe and assume there is a bias pot internally? What should the bias be set to for these amps?

[stephen sawall]

I think mine are EH. I bought my tubes from Fryette.

[jc986]

Didn’t know you could buy them directly from Fryette. That’s good to know. Do I just email them to do so, or is there a number I can call?

Still waiting on a response on buying an effects loop for the D120 to have a local tech install.

[stephen sawall]

If it has the original Fryette tubes in there you will find a number on the tube. Let them know the number and you normally would not need to bias. I would bias anyway since you just got it.

I think there is a number on their site....maybe ?

[jc986]

I was able to find the phone number by searching for the location on Google Maps. Called and spoke with them, but they are currently out of stock of KT88’s. They recommended EH. Mine do have the number, but not a big deal. I planned to re-bias anyway since the same tubes have been in the amp over a decade.

Just out of curiosity I took some ma readings for each tube just to see, and looking at the amp from behind, the readings were 45ma, 34ma, 37ma, 49ma. When I first tried to get the readings, the left 2 sockets gave me no reading. All the tubes are lit and look the same but I found it very concerning that 2 of the tubes weren’t giving a reading. I’m just using a bias probe and standard multimeter that I’ve used to bias other amps at least a dozen times. The amp sounds great though so it made me wonder if there’s an issue with my bias probe by chance. I did the readings from the right initially, so I swapped the far left and far right tubes and took a reading in the far right spot. This time the tube gave me a reading... I have no idea what would cause 2 of the tube sockets not to give a reading. I swapped the middle 2 tubes and took a reading and also got a reading from the other tube in that socket. So it seems the tubes are ok (albeit not very well matched or the age has caused them to drift), but the left 2 sockets don’t give me any reading whatsoever with my bias probe.

[metalhobo]

there is a bias trimpot inside, and moreover there is a current resistor in series with the cathodes and some silkscreened text telling you what the target voltage should be.

[jc986]

Cool, thanks. I ordered the FX loop kit from Fryette and a quad of EH KT88’s from Doug’s Tubes.

[stephen sawall]

How much was the effects loop kit ?

I'm thinking about putting one on my D120.