6505+ Tube Question

[Stratman95]

I recently bought a used 6505+ head. The amp sounds great but I noticed there was some background noise that I thought was a little excessive. I don't know how old the head is, and don't know it's history. I thought that new tubes may be needed so I looked at them to see if anything looked out of the ordinary. It has a 6L6 tube in the leftmost position but the other three are EL34 tubes. I was under the impression that you could modify this amp to use EL34 tubes but that it was an all or nothing arrangement. Doing some research I saw that you could modify the amp to use EL34 tubes but that you couldn't just mix and match them. Does anyone have any input into this? I've attached a picture for reference.

 

[RaceU4her]

Yikes

 

[LP Freak]

WTF? I’m not sure about the mod but you definitely can’t run 1 6L6 and the rest EL34’s. I’m surprised it hasn’t blown a fuse.

 

[Stratman95]

I thought this was odd as well and am pretty concerned as to why they chose to do this. It does power up and play with no issues but I think I'll be taking a trip to a local shop to see if they can't figure out why this was done.

 

[the4thlast1]

Wow ! Get those tubes out of there asap. I like either the Ruby/TAD 6L6s or Sovtek 6L6 Wxt+ both sets sound great in that amp.

 

[fusedbrain]

The only mod for that amp to run el34's is a new power transformer.
The stock pt can't handle the heater current draw of a quad of el34's.
Switch to a quad of 6l6's asap!

 

[Stratman95]

I've got a set on order now and will replace them asap. Thanks for all of the input!

 

[GregM]

I finally just bought one too so I'll tag along on this thread.

Mine will be used mainly for metal and will see mostly EMG's and probably some Fishman actives with an OD808 in front of the amp. Any recommendations for preamp and power tubes? I just got it last week used and haven't had time to open it up and see what's in it yet or check bias.

 

[indespise]

Those are biased so cold and there's so little travel in the pot that you don't have to worry about biasing unless you do a bias mod. But as said earlier, stick to 6l6 tubes.

 

[Bad.Seed]

Sounds like the guy stuck whatever spare tubes he had laying around in it when he sold it. People are known to do this, that's why I always try to ask what tubes are in it, and I confirm it when I see it. Something you pick up when buying used gear and getting screwed. Haha.

I wouldn't continue to run it like that, get yourself some matched 6l6's to throw in it

 

[Exo-metal]

A real friend musta sold that to you. My advice, get a new friend.

 

[Metal1977]

All power tubes in your amp are 6L6's, some are just mislabeled as EL34's. I also noticed that the last tube on the right doesn't look aligned like the others. You should check if the guide key is broken on that one just to be safe. Anyway it wouldn't hurt if you change them.

 

[itsme]

All power tubes in your amp are 6L6's, some are just mislabeled as EL34's. I also noticed that the last tube on the right doesn't look aligned like the others. You should check if the guide key is broken on that one just to be safe. Anyway it wouldn't hurt if you change them.

I agree. Those are not EL34's. I know the BHT 34's are fatter than normal ones, but not that fat. Nonetheless, I'd probably replace them with a fresh set anyway...

 

[Stratman95]

I bought this amp from a national retailer store that happened to be local to me, not a friend or Craigslist. For that reason I couldn't follow up with the previous owner. This is my first tube amp and I must admit I don't know much about the different tubes apart from what I've read online. Just out of pure curiosity, why would you assume the tubes with the label marked EL34 are 6L6 tubes? I admit the size difference isn't much. No disrespect intended, it just struck me as strange that an amp designed for 6L6 tubes would have an EL34 sticker on three of the tubes.

 

[Metal1977]

I bought this amp from a national retailer store that happened to be local to me, not a friend or Craigslist. For that reason I couldn't follow up with the previous owner. This is my first tube amp and I must admit I don't know much about the different tubes apart from what I've read online. Just out of pure curiosity, why would you assume the tubes with the label marked EL34 are 6L6 tubes? I admit the size difference isn't much. No disrespect intended, it just struck me as strange that an amp designed for 6L6 tubes would have an EL34 sticker on three of the tubes.

I don't know why some of your power tubes are mislabeled, i've never experience something like this. You clearly have 4 Ruby 6L6 GCMSTR in the amp.

Ruby - 6L6 GCMSTR


Ruby - EL34 BHT

 

[Stratman95]

After seeing the pictures of the two tubes next to each other, I can see why you guys are saying they are all 6L6. The black piece on top is much smaller on the 6L6 tubes. I still find it strange that they are marked incorrectly, just makes me wonder how many have had this issue.

 

[SQUAREHEAD]

Yep, those are all 6L6 tubes, check that fourth one, I agree, it’s not lined up properly…

 

[FourT6and2]

lol well now that's something you don't see every day

 

[sg guy]

Those are biased so cold and there's so little travel in the pot that you don't have to worry about biasing unless you do a bias mod. But as said earlier, stick to 6l6 tubes.

----TRUTH!!!----------------
-a bias mod will be a much bigger benefit to your tone than replacing those tubes...

 

[SQUAREHEAD]

Those are biased so cold and there's so little travel in the pot that you don't have to worry about biasing unless you do a bias mod. But as said earlier, stick to 6l6 tubes.

----TRUTH!!!----------------
-a bias mod will be a much bigger benefit to your tone than replacing those tubes...

Absolutely… Those things idle around 10 - 15 mA, it’s just crazy frigidly cold !