I've been liking my CJ5 preamp a great deal. I am going to let the LP-27a go. If there was a strong interest, I would consider letting the Firebottle amp go along with it. For the sake of a proper set of equipment.

Tried a 7f7 as an input tube for my Firebottle kt88 the other night. It is the equivalent of a sylvania 6sl7. This one is known as a "chrome dome" because of the way the silver on the inside of the tube extends to cover most of the tube. I've kept my Ferranti 807 tubes in for a while now.

I was initially blown away by the bass this new tube gave me. It was significantly tighter and had more impact than the various 7n7 (sylvania 6sn7) tubes I had been using before. With extended listening I found the higher frequencies to be harder, or at least annoying lol. Went back to the short 7n7 with the small top getter. It is much better tonally and goes just as deep but I do miss that bass crispness.

Sigh, the quest for the perfect input tube continues!

Went back to the 7f7. Sounds amazing. Have to keep reminding myself that I am the biggest variable when it comes to subtle differences!

I went down to my father's place for the first time in over a year thanks to covid. I finally retrieved my tube stash after 12-13 years. I had gone on a tube buying frenzy and then moved out of the country.

I, uh... bought a lot of tubes. Lol. I must have 200+ here. All of them were bought with the idea of doing DIY stuff. All of them are useful audio tubes but only a handful are useable in commercial equipment.

In particular I have a bunch of old 6v6 and 7c5 tubes, mostly Sylvania. I do also have some 6sn7 and 6sl7. All of these can be used in my Firebottle. As a tube roller enthusiast I'm stoked to try them out. Now what to do with all the other ones....

Hello Forum Friends,

I have heard of people on other forums using 46 and 71A tubes with an adapter with their 45 tube amps. Has anyone tried this? Can this be done with my Inspire 45?

Thanks rmlowz

On my Firebottle KT88 HO, when I used a 6SL7 there was a LOT of high frequency detail. At first I was amazed by the detail and big soundstage, but over time it literally gave me headaches.

Briefly tried a 6BX7 and the Inspire tube magic disappeared. Harsher, less natural, less midrange magic.

Over the past 2 years I've exclusively used 6SN7 in both of my Inspire amps. The better ones sound great to my ears. Open, transparent, great midrange, big soundstage, well defined bass. Good high frequency detail without being harsh or bright.

I have gone back to the 6sl7 and been enjoying it. Think the music I was listening to originally didn't pair well with it. That is something to keep in mind though, not sure if sounding amazing on some music overcomes being annoying with other music especially since the 6sn7 doesn't offend at all.

Once I get back home I'll do more listening. I'll have a whole slew of new tubes to try too.

The latest and greatest...
 

Dennis has been perfecting an upscale version of a pre amp that we have been monkeying around with for the better part of 3 years, and as some of you may already know, is called the LP-71A.

Before I go any further, let me tell you all what Dennis has said about this new design, and I quote...

"Not only is this the best pre amp I've ever designed, but it is the best pre amp I've ever heard"

What more is there to be said?

One of the nice things is that it will run three different types of tubes interchangeably, the 12/112, the 01A and variants, and of course the 71A and it's variants. I won't try and describe how it sounds. Let Dennis' comment speak for itself...

https://live.staticflickr.com/65535/...1e73ac29_b.jpgUntitled by analog addict, on Flickr

https://live.staticflickr.com/65535/...d6073d53_b.jpgUntitled by analog addict, on Flickr

https://live.staticflickr.com/65535/...e5e71d7d_b.jpgUntitled by analog addict, on Flickr

Amps for today were a 45 SET and a PSE 6V6 prototype wired in pentode.

https://live.staticflickr.com/65535/...51aa1544_b.jpgUntitled by analog addict, on Flickr

Here's my preamp, which I suppose one could call the original prototype on the bench. Check out that square wave... Perfect! Even with the gain turned up to 11, the sine wave is perfect and undistorted.

https://live.staticflickr.com/65535/...8e94ffd0_b.jpgUntitled by analog addict, on Flickr

Finally a shot with some thoriated filament globes installed. These tend to be a bit more finicky because of the microphonics and the fragility of the innards, but they do shore look nice...
https://live.staticflickr.com/65535/...b81a9677_b.jpgUntitled by analog addict, on Flickr

I listened to a 71a based preamp at a dealer last month. Sounded amazing but if you flicked the tube with your finger it rang like crazy! Make sure you can isolate the preamp if you get this one. What are the other tubes?

Oh yeah, you can tap out a tune on the pre amp chassis if you want. Nothing in life is 100% perfect.

Mine uses a single 0A3, a 5AR4 rectifier, the two signal tubes, and a 6SN7 for the center channel mixer. The official LP-71A uses two signal tubes, a 5U4G rectifier and an 0A3 for each channel.