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-   -   Dennis Had Inspire Amps (https://www.audioaficionado.org/showthread.php?t=24170)

FloridaBoy 08-02-2015 05:39 AM

Quote:

Originally Posted by jimi55 (Post 717455)
You might want to try the 807 tube. It is quite nice too! 807 to 6L6 adapters are available on that auction site.

Ditto for 6BG6's. :thumbsup:

Beatlebum 08-02-2015 06:43 AM

Quote:

Originally Posted by FloridaBoy (Post 717559)
Ditto for 6BG6's. :thumbsup:

FloridaBoy,

Just want to make sure I'm following you correctly here. Are you suggesting the use of the 6BG6 and the previously mentioned Tung-Sol's as power tubes in lieu of KT88, KT77. 6L6's? My Inspire IFA-1 came with Sovtek KT88's and I've also got the GL KT88 reissues (very nice) as well as some RCA 6L6GB's that sound great too!

FloridaBoy 08-02-2015 10:43 PM

Quote:

Originally Posted by Beatlebum (Post 717562)
FloridaBoy,

Just want to make sure I'm following you correctly here. Are you suggesting the use of the 6BG6 and the previously mentioned Tung-Sol's as power tubes in lieu of KT88, KT77. 6L6's? My Inspire IFA-1 came with Sovtek KT88's and I've also got the GL KT88 reissues (very nice) as well as some RCA 6L6GB's that sound great too!

Yes, the 6BG6 is a 6L6G with an anode cap. It needs an adapter as does the Tung Sol. The adapters and a pair of tubes are not a lot of $$$ and sound great.

As another poster said, you can also use 807's with adapters. There is voltage under the cap of the adapter so be careful if you have small children around.

FloridaBoy 08-03-2015 11:02 AM

Tube substitution handbook
 
You can Google 'tube' substitution handbook and find PDF's that give direct substitutes for various tubes, power, rectifier etc. or you can purchase a hard copy. It's a great reference. Just don't try something unless you are certain it is a direct sub. :D

FloridaBoy 08-03-2015 04:52 PM

Just a word of caution. Don't pay a lot for the 6BG6 and 807's. They may be NOS but they can be microphonic and gassy.

Not so the Tung Sol 6AR6 at least for me. Knock on wood.

Aercool 08-03-2015 11:51 PM

Microphonic I understand - but can someone describe how a "gassy" tube manifests itself? Seems like if the vacuum was failing and air was getting in, the shiny getter would begin to turn chalky, all internals would suffer a swift fate. What does a gassy tube sound like?

FloridaBoy 08-04-2015 08:08 AM

Quote:

Originally Posted by Aercool (Post 717958)
Microphonic I understand - but can someone describe how a "gassy" tube manifests itself? Seems like if the vacuum was failing and air was getting in, the shiny getter would begin to turn chalky, all internals would suffer a swift fate. What does a gassy tube sound like?

I'm not an engineer or tube expert, and I don't want to be. I am just an experienced user. Glass can 'leak' a little over time and cause a tube to be gassy. This happens when a tube is stored for a long period of time and not used. This is not good sonically or electrically. It seems to occur more often in power tubes than small signal tubes. Perhaps because of the larger bottle? I have read posts about NOS Tung Sol 6550's being gassy. A gassy tube can arc and there is a possibility of losing a transformer. They sound distorted and you will see swirls of blue and purple. The best insurance is to buy these older tubes from a dealer that tests them for these issues or avoid them altogether. The Russian 807's are pretty well regarded, are of more recent manufacture, and don't have this problem. Ditto for the Tung Sol 6AR6..but get them from a dealer to be sure.

Google gassy vacuum tube.

FloridaBoy 08-04-2015 10:20 AM

Seller's description
 
CBS HYTRON JAN 6BG6G TIGHT MATCH PAIR NOS NIB MINTY VINTAGE 1952...This pair is NOS in original box and in excellent condition and they test right in the NOS range...One has a couple of glass floaters in the bottle which is not uncommon for these types of tubes, and because glass is not electrically conductive they should perform perfectly...

Tested NOS range...This does not necessarily mean that the tube is new, but tests at or above new tube typical minimums...New tubes typically test 80-85 for quality on my tester with a minimum good reading of 65...It is also possible that new tubes can test below this minimum, but again, on average most new tubes test in or around that range ...

Tester: Calibrated and very consistent B&K 606 DynaJet where NOS typically test 85-90...


Tube"s test as follows...

Tube 1 tests...87

Tube 2 tests...93

Shorts, Gas, Grid Emissions-None

I bought these on the auction site from a seller I trust and have purchased from before. The tubes were thoroughly tested but I will keep an eye on them for the first few hours of use. Also, I plan to use them in rotation.

FloridaBoy 08-04-2015 06:15 PM

Inspire 6AR6 amp
 
I told Dennis how much I was enjoying the 6AR6 tubes. So he decided to build a 6AR6 amp. :D

Here is an excerpt from and e-mail he sent:

Now look what you have done !!! ..... Holy Crap ... Now what do I do????
With a dedicated design for the 6AR6 or 6384 tubes I am in Hi Fi heaven. As
I mentioned the output transformers are specifically designed for the 6AR6
plate curve impedance. The driver is the 6922 with a regulated B+ supply
and dual auto bias system on each of the 6AR6 output tubes. All I can say
is Holt Crap ..... this is a life time amplifier. Oh, I might mention ...
the 6AR6 and especially the 6384 ain't no 6L6 sub ... the sonic merits along
with the plate impedance in the triode mode is completely different along
with the sonic merits.

http://i57.tinypic.com/27zdgld.jpg

pstrisik 08-04-2015 06:21 PM

Very cool! Did he offer any opinion about running these with adapter in his pentode UL amps (as if a 6L6 sub)? I'm tempted to try since it would be a relatively inexpensive experiment.


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