tubeman.com has 807/CV124 tubes Ferranti Brimar British Military for $39.99 a matched pair.

Have you tried it with a 6SN7 instead of a 5691/6SL7? The 6SL7 is a much higher gain tube. When I tried one in my Inspire, the sound was much more harsh than with a 6SN7.

I might give up on using 807s entirely given your results, but you could try using a 6SN7 and a 5V4GA rectifier (lower voltage, lower current).

Got a big surprise from my Inspire KT88 HO amp tonight. I picked up a couple of the 1970s Russian military 6H8C tubes, which are 6SN7 equivalents. I decided to burn one of them in, leaving the other in the box for an eventual comparison of brand new vs burned in. I didn't want to burn up a lot of hours on a set of the good power tubes, so I installed a pair of new production EH 6CA7. I listened to them for a few hours many months ago and found them okay but nothing special.

Popped in a CD and to my surprise, a big warm tubby bass sound came out. By far the most bass emphasis I've ever heard out of the amp. My vintage USA 6CA7 fat bottles have always had a bit of extra mid-bass energy, I like using them when listening to blues and three piece jazz combos. This combo goes well beyond that.

The bass isn't as powerful, deep or well-defined as when I'm using KT150 or KT120 tubes.

When I had the 6H8C paired with the KT150s, I had noticed a bit more bass emphasis.

I'm going to let this combo run for a few days. Run in these tubes. Already listened to two CDs taking note of the different presentation. Need to get out some blues and turn my living room into a nightclub.

I picked up an assortment of 22 6sn7gt tubes and in the mix was 4 gray glass RCA’s, 2 black glass tung-sol and 2 ken rad black glass.I tested them and they all test strong.I put the tung sol in the preamp and the a single ken rad in the amp and the bass response is the best I have had with these pieces.I was thinking of selling the amp and preamp but not now.

I need to find deals like that, better bass response nothing like hearing and feeling a kick drum or a cello ! I guess I don't search the right places LOL
rmlowz

Finding the right tubes for your rig makes a HUGE difference. Trial and error plus some dumb luck usually works for me. :thumbsup:

And ironically for me, about 50/50 for recs read on the internet [emoji848][emoji6]

In the end I pulled all of these back out of my amp. The 6H8C were decent, listenable, but not the best I've heard. Certainly value at $9 each.

I now like the EH 6CA7 better than I did before, but still not all that much. They produce a warm presentation, but vocals aren't as magical, the soundstage is diminished. Overall just not worthy to be in an Inspire amp. Perhaps okay in a ST70 or inexpensive amp.

The tube asylum on Audio Asylum is a great place to search for tube information. You can get a general idea of what may work for you.

I have a kt88 inspire amp and have been noticing some transformer hum through my speakers. Amp is plugged into a audioquest niagra 1200
Any recommendations ok how to mitigate this ?