Dennis Had Inspire Amps

[Bombadil]

Lucky me.

I have this box of old tubes. Tried to sell it twice last year for $40 and the buyers backed out both times. I knew it had some good tubes in it. Now that I have the Inspire KT88 HO, I went back through it and found five 6SN7s and 4 6V6GTs. All test and sound good. So I'm lucky that I didn't sell it.

Now double lucky, I have a friend with lots of old tubes. I went over today and sorted through his box and found 4 more 6V6GTs, all vintage USA tubes ... Tungsol, RCA, and Magnavox. He said he thought they were good as he throws out bad tubes. Offered them to me at $5 each. So I bought all of them for $20.

Got them home and ran them through my tester. Turns out that between the 8 tubes, I have 4 matched pairs on transconductance, with all of them testing as new or close to new on emissions. I may now be set for life on 6V6 tubes.

[Bombadil]

About 45 minutes ago, I swapped in a matched pair of old stock USA Tung-sol 6V6GTs, along with a 5V4GA rectifier and an old Westinghouse (rebranded) 6SN7 from the 1950s.

Wow! Does this sound different than my first listen to 6V6GTs a few days ago. Much more detail, much more refined bass, throws up a wide, deep soundstage. Very, very nice.

Then I kicked in my subwoofer and filtered out everything under 80Hz, to ease up the load on the 6V6s. They were doing pretty good but I was driving them hard into 89dB speakers. This cleaned up the presentation a bit more. Now able to drive this setup to fairly loud levels.

I don't know how much output I get from the 6V6 in my amp, I saw the earlier posts which showed the Inspire amp which gets 12 watts from KT88s, got only 5 watts from 6V6s with a 5Y3 rectifier and 7 watts with a 5AR4. As my amp gets 17 on KT88s, I imagine it drives the 6V6s a bit harder too.

I am liking the 5V4GA in this amp. A little more relaxed from the 5AR4 / GZ34. I also like the 5U4 and 274B. Will be giving longer listens to the GZ34 in the future.

[FloridaBoy]

If you like 6V6's consider a pair of Pope 6V6GT's from Upscale. They are outstanding. YMMV.

[Comzee]

Just picked up a Fire-Bottle kt88 version from Dennis a few weeks ago.

He was telling me I could roll 6v6 + 5u4gb, of which I have.

I was wondering though, can I mix and match the rectifier and output tubes?

For example, can I use KT88 + 5U4GB OR, 6v6 + gz34.
If I can, what are the implications, if any?

[Bombadil]

Yes, those Pope 6V6GTs have been mentioned several times earlier in this thread. There's a lot of good information buried in these 200+ pages.

However at those prices, I will likely stay with what I have.

[Comzee]

Thanks for the info @Bombadil

Here's another curious thing to me.

I know these amps are somewhat related, my "Fire-Bottle" and the "Inspire IHA-1"

An interesting quote from the Moon Audio write up.

"the rectifier tubes should be of the direct heater type like the 5Y3, 5U4, 274B or NOS and factory fresh direct heated filament types. The indirect filament type like a 5AR4 are fine to use but to his ear they do not even come close to a directly heated filament type."

My Fire-Bottle shipped with 5AR4/GZ34, which I can assume is "indirect filament type" based on the above quote.

I'm wondering why Dennis would say indirect filament rectifiers are bad, then use one in his Fire-Bottle. Thoughts?

[jdandy]

Comzee.......Welcome to Audio Aficionado.

[nhparrot]

Originally Posted by Comzee

Just picked up a Fire-Bottle kt88 version from Dennis a few weeks ago.

He was telling me I could roll 6v6 + 5u4gb, of which I have.

I was wondering though, can I mix and match the rectifier and output tubes?

For example, can I use KT88 + 5U4GB OR, 6v6 + gz34.
If I can, what are the implications, if any?

you can use a 5U4G with the 6V6GT tubes, but need a 5Y3 for the vintage 6V6. I produced somewhat of a guide for the amp I have, which was built on 1/2/15. There is a tube chart in it

https://drive.google.com/open?id=0Bw...EYza1l5SDhQNzA

[FloridaBoy]

Originally Posted by Comzee

Just picked up a Fire-Bottle kt88 version from Dennis a few weeks ago.

He was telling me I could roll 6v6 + 5u4gb, of which I have.

I was wondering though, can I mix and match the rectifier and output tubes?

For example, can I use KT88 + 5U4GB OR, 6v6 + gz34.
If I can, what are the implications, if any?

Some 6V6GT's can handle a GZ34. I've not tried it as the 5U4G sounds quite good.

[FloridaBoy]

Originally Posted by Comzee

Thanks for the info @Bombadil

Here's another curious thing to me.

I know these amps are somewhat related, my "Fire-Bottle" and the "Inspire IHA-1"

An interesting quote from the Moon Audio write up.

"the rectifier tubes should be of the direct heater type like the 5Y3, 5U4, 274B or NOS and factory fresh direct heated filament types. The indirect filament type like a 5AR4 are fine to use but to his ear they do not even come close to a directly heated filament type."

My Fire-Bottle shipped with 5AR4/GZ34, which I can assume is "indirect filament type" based on the above quote.

I'm wondering why Dennis would say indirect filament rectifiers are bad, then use one in his Fire-Bottle. Thoughts?

The 5AR4 is indirectly heated.