The 807 do need an adapter. They are a great value tube! A great way of getting vintage 6l6 sound for a lot less money. The 6bg6 is essentially the same tube with a different pin out. The 6bg6ga got some more powerful guts put in them towards the end. I think the 6bg6 route is an even better deal unless you want to collect the likes of GEC, Mullard, etc. then go 807.

There has been a lot of raving about the metal 6f6 in the Firebottle. My first experience with some RCA 6f6 wasn't a good one. They were bright and lightweight in general. Wasn't impressed. I eventually decided that with so many people liking them I should give them another try.

Got some KenRad 6f6 metal tubes. They along with the cv1102 and RCA 5y3 sound great! I might try some other input tubes but then again I might not lol. Certainly a great deal. I think that low powered pentodes are the place to be money wise in these crazy tube times. Lots of great deals to be had!

Visseaux 6V6GT come up for sale rarely and the asking price is around $300+ a pair when they do

807s and 6bg6s need adapters. Do a search for the Visseaux 6V6 on epay. I just saw a NOS pair that sold on 6/27 for $199 but it now. That was a super deal.

Thanks. Just pulled the trigger on Fivre and Ferranti’s from your recommended seller.

Now I need to buy a 5Y3 rectifier since I recall that the 5U4G that I’m currently using is not a good match for the 6V6G type although I suspect it will be fine for the 807’s.

Speaking of 807’s, who makes good quality adapters for it?

I’ve bought some off of eBay and they work fine. If you want another option that isn’t Chinese I now use a guy in Bulgaria that can literally build you any adapter you want. I just bought a system of his that allows me to use other heaters voltages so I can use my 12sn7 stash on the Inspire amp. He hangs out on Head-Fi where all the tube loonies are. https://www.head-fi.org/classifieds/...dapters.11214/

Thanks Isaacc7! Lots of good reviews. I just reached out to him. Now to figure out the 5Y3 rectifier for the Fivre’s…

Thanks nhparrot and OldTubeGuy on confirming the going rate of the Visseaux. The guys who sold me his Popes also has a pair of Visseaux and was willing to let it go for $350. I wasn’t sure about that price so I decided to pass. I may revisit.

For now, the Fivre and 807’s are on their way and I am trying to decide whether I want to cough up $60 for the 807 adapter from the Bulgarian builder Isaacc7 recommended and also get a 5Y3, which shouldn’t be difficult.

Like I mentioned before I also use Chinese adapters from ebay and they're fine. So if you want to save a few bucks that's an option. I think Deyen's connector is a little gentler on the top cap. One of the caps on my Cossor/GEC 807 got stuck in the cap of the Chinese adapter. So that tube is out of commission until I figure out how to fix it.

Which 807 are you ordering?

I ordered the Ferranti 807’s that OldTubeGuy recommended. They were cheap enough to give them a try. I havn’t given up on Deyen yet. Just evaluating options. I looked at another source and they were selling one for $30, so his price isn’t necessarily outrageous.

Try getting some dielectric lubricant into the top cap. I've had no issues with the Chinese adapters so far.

Just get a 5Y3G and be happy. There is a nice Silvertone 5y3G on the auction site for $22.95, $7 shipping.

Those Ferranti’s are a steal! Sound great. I think I have bought my last 807s, at least for a while lol. I now have the Ferranti, Cossor, Mullard, and just today I got in some Fivre and Mazda as well. Also have some funky loctal 807 from STC that needs an adapter. I will definitely get some more 6bg6ga tubes in the future though. They are related to 807.

Well....
 

First off a disclaimer.

Tube amps that are powered up contain LETHAL voltages. One must always be very careful when sticking your hands or tools attached to your hands inside one, even one that has been powered down. The big power supply capacitors can maintain lethal charge for quite some time, especially if the power supply has no bleeder resistor to drain off the accumulated charge. Always better to stick one hand in your pocket when working on one, and to wear shoes with rubber soles, even flip-flops. Bare feet on a concrete floor like my workshop is asking for it. I would also wrap any needle tipped probes with some shrink tube so that only the most distal tip of the probe is uncovered. Shorting out components under full operating voltage may very well let out the magic smoke.

Can you read a schematic? Solid State schematics differ somewhat from toob schematics due to different types of components used. Anyway, to measure the power transformer output, you measure the high voltage output leads as they connect to the rectifier socket. This will be ACV.

Then you measure the output voltage, either at the socket or the + terminal of the first capacitor after the rectifier. This is DCV, and measured w.r.t ground, i.e., measure with the red meter lead on the positive terminal and the black lead on the negative . That will give you the voltage drop of the rectifier. Simple, no?

Is it ok to use a 5Y3GT rectifier with 6V6GTs?

Instead of taking the bottom of the amp off and poking around a live amp, could I use something like this?

https://www.amazon.com/Nobsound-Vacu...ps%2C77&sr=8-4

If that gives me the bias current couldn't I use that number to figure out the voltage somehow? Isn't this built into the current Firebottle amps now?

3 for 3 now. I just bought it even though I was contemplating other more expensive alternatives. Brent Jesse was very high on Bendix, Mazda, and Brimar all at $99 each.

Messaged Dennis as well. He said, while the Bendix would work, he isn’t a fan. So there’s that. He had suggested a coke bottle shaped RCA of GE 5Y3G and the Silvertone (is that a manufacture or relabel) fits that criteria and seemed in line with the price I paid for the Fivres.

Oh this just occurred to me, which rectifier for the 807’s (still finalizing the adapter)—the 5U4G or the just bought 5Y3G?

You can use either. The 807 can handle more voltage. Giving it less with the 5y3 is bound to change the sound but it won't harm anything.

I use an RCA 5y3 and 5u4gt. Also have a Japanese 5ar4 and a Russian one along with the one that came with the amp. I don't use the 5ar4 though.

Yes, you can use a 5U4G or 5Y3GT. Let your ears decide.

That's why I'm asking. 5U4G sounds great...5Y3GT sounds sublime!

Any updates on the phono pre? Would love to get my hands on one.

Thanks OldTubeGuy and Isaacc7–noted. I learned that the Silvertone I ordered yesterday was a Sears label, made by RCA.

Correct, tubes were relabeled back in the day. Have you tried a 6BX7 as the input tube? I put a GE in with the Pope 6V6 and 5Y3. Nice, and they are inexpensive.

I've had a pair of Russian Gold Lion 6V6s for years and did not care for them...until I put them in the KT88 SE. Big ballsy sound.

All of my input tubes are NOS 6SN7’s at the moment, but I’ll take a closer look at the 6BX7 especially if it’s inexpensive.

Speaking of Gold Lion, have you or anyone else has any experience with their new production 5AR4/GZ34 rectifier? One has come up for cheap and I was wondering whether to pull the trigger or hold out for a NOS Mullard perhaps?

I have a Mullard and never use it with the Inspire. No experience with the GL.

Does anyone know if an original tube box from Upscale Audio has a Cryo’d sticker, does it mean it was cryo’d or do they put these stickers on all their boxes? I think its the former based on the following two sets of tubes I purchased used:

1) 1950’s CBS Hytron 5692 - Kevin’s Stash sticker but no Cryo Sticker
2) 1960’s Pope 6V6 - Only a Cryo sticker

I recall someone telling me that they only put those stickers on if they were actually cryo’d but wanted to know if anyone else has a similar experience?

Does the input impedance of the amp change when we use different input tubes? Finally getting a chance to try an ecc81 and I'm getting a really weird result. I'm used to tubes giving me a different sound but this takes it to another level. I'm getting a big boost in the lower treble and a complete suckout of the midrange. I'm guessing that my passive preamp can't drive it properly and/or the ecc31 can't properly drive either the 807 or 6f6 that I've tried. Any guesses?

Hey C10, the fabricators are making the chassis, I'm not sure how long that will take.
Then they go to the powder coater which take's about a week.
After that it's just a matter of getting the parts in and building them.

Appreciate the update! Thank you!

If anyone os thinking bout getting one of Dennis's amps he has an older one up on ebay at a great price. https://www.ebay.com/itm/15506501971...cAAOSwKn5iw0vZ

Lol, you just beat me to this Public Service announcement. Sounds like a great deal!

Update 1: Closed on a deal for NIB/NOS (original box) Visseaux 6V6 for $230 yesterday.

Update 2: Expecting to receive the Silvertone 5Y3GT and Fivre 6V6 tomorrow.

Went back to using the cv1102 and Cossor 807. An amazing combo, well recorded music is downright eerie sounding it's so realistic. The Andrew Bird song "Fiery Crash" has a guitar that comes in on the left side towards the end of the song. Heard the song many times before but this time I got goosebumps when it came in. Couldn't help but smile!

So received the Fivre’s, Ferranti 807’s and Silvertone 5Y3 rectifier. First up, I wanted to test the Fivre’s with the 5Y3.

As soon as I turned the amp on after switching the power and rectifier tubes, I noticed that the rectifier was rattling but it quieted down in a minute but then I started hearing slight popping sounds from my left speaker. Messaged Dennis and he suggested that the Fivre 6v6 tubes might be noisy and to take out the rectifier and let them burn in after a few hours as they might have been just sitting unused for decades.

Burned in this manner for 3 hours. Plugged the rectifier again and again the same rattling sound for only a min and then then starting hearing the popping sounds. This time I figured I’d play some light jazz to see if I can pick up the noise and good news, I can’t. However, between the tracks, I can detect the small popping noise though it seems to be dissipating, not entirely sure at this point. Will keep testing tomorrow to see how it fares.

That said, everything I’ve played so far sounded wonderful. I am assuming the initial rattle of the 5Y3 rectifier is normal?

Maybe the rattle won't harm anything but I wouldn't call it normal. I've never noticed any noise coming from the rectifier before.

The 'official' input tubes for the KT88 SE are 6SN7,6SL7 and 6BX7.

What's going on isn't normal. Return the tube.

Update: The tapping of the left speaker had vanished by midnight. Today, I turned the amp on at noon, there was that initial rattle of the rectifier that subsided to a faint hum, which I can only hear if I put my ear right next to the tube. Not sure if all rectifiers have a hum if you listen up close (I never tried doing that with the GE 5U4 so not sure). Left speaker was noisy again for less than a minute but it’s fine for the past 6 hours. Good thing is the Fivre’s sound wonderful. Initial impressions is that I am liking them better the Popes but haven’t had much time to do critical listening. I will contact the seller of the Silvertone and send him a video I made of the initial rattle of the 5Y3 upon start-up and gauge what he is willing to do.

Update 2: The Visseaux arrived early and probably has one of the most beautiful original tube box I’ve seen to date. See pictures I linked in this post (hope they come through). I won’t have a chance to test them until the weekend so let’s see if they sound as good as the boxes look.https://share.icloud.com/photos/0af2...JB9RHym5nGqq_w
https://share.icloud.com/photos/02fc...YbCi06qxg0XxSg
https://share.icloud.com/photos/09cJ...n6gt2X1Wsl8vIQ
https://share.icloud.com/photos/092z...okwdyDlLCkGDMw

Crossover day...
 

I went by the shop yesterday to see what Dennis had been up to. He told me that he had been working on the crossovers for a pair of my speakers that had been sucking up space in the back of the shop. These are most likely buried in this thread somewhere, but were a quick mock up of an open driver set up of a vintage Altec 604-8G pair I had lying around.

Here is Dennis soaking it all in...

https://live.staticflickr.com/65535/...5aa34cba_b.jpgUntitled by analog addict, on Flickr

https://live.staticflickr.com/65535/...fa8479f6_b.jpgUntitled by analog addict, on Flickr

And here is the bad boy powering the set up...The Mighty 46 Amp!
Pure sonic bliss with a mighty 2 watts. Sounds like a 45 on steroids to me. Dennis likes it better than the 45 tube.

https://live.staticflickr.com/65535/...2f5e8d32_b.jpgUntitled by analog addict, on Flickr

And then, there's this....

https://live.staticflickr.com/65535/...03b1131d_b.jpgUntitled by analog addict, on Flickr

The brand new phono pre featuring a separate power supply. Dennis said that he has ordered 25 sets of these chassis, so get in line quick before they're all gone. Who knows if he'll make any more?...

Lastly, the crossovers.

https://live.staticflickr.com/65535/...b241d4b6_b.jpgUntitled by analog addict, on Flickr

Dennis absolutely loved the 604's with his custom crossover. He said the sound became "real" once he got it dialed in...

So, since we were messing with Altecs, I toted out the second set of Altec loaded speaker hiding in the back of the shop. These are EV Aristocrat cabinets loaded with a 416A woofer and a 902 compression driver loaded on a (I believe) 9344 small horn. There was a set of old crossovers that had been built earlier, but Dennis said don't waste your time with them. The "Altecrats" sounded very nice, but couldn't match the classic duplex. I will have to fiddle with them more....

https://live.staticflickr.com/65535/...175b815e_b.jpgUntitled by analog addict, on Flickr

Oh man, I had no idea I wanted a 46 based amp lol. Would love to hear it. By my reckoning I am rarely ever going over 2 watts with my system. Luckily for me I doubt this will be priced low enough to make it an impulse buy. But who knows, maybe Dennis will surprise me? Lol.

That used to be my amp that was my first Inspire amp. I really liked it. I bet it sounds even better with the updates