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

straitwire 12-06-2020 12:08 PM

Hello everyone, I was too busy yesterday to relay any detailed information about amplifier heat.
The KT88's are the reason the unit is slightly hotter than with smaller tubes, this is normal and the amp is fine.
The power transformer is rated to 103° Centigrade (217° Fahrenheit).

khill007 12-06-2020 12:10 PM

Quote:

Originally Posted by rmlowz (Post 1023632)
I was wondering has anyone tried 7581 tubes? I want to buy some different tubes for my Inspire Universal.
Thanks
Rich


The Philips ECG 7581a is one of the best sounding 6l6 variants on the planet in these amps. The only tube I’ve used in both my 6FLV and my universal that bested them (and I have tried everything out there in both amps) were WE350b’s in the 6FLV. The Philips are pretty rare and pricey but worth it if you can find them. (Green letters, dual top getters, 80’s production)

Believe it or not the Tung Sol new production 7581a is no slouch either.

straitwire 12-06-2020 04:48 PM

Ok, forget everything I said...
The power transformers are rated to 103° Centigrade which is 217° Fahrenheit.

rmlowz 12-06-2020 06:51 PM

Believe it or not the Tung Sol new production 7581a is no slouch either.[/QUOTE]

That's the ones I ordered from Viva be here Tuesday
Thanks
Rich

paulmlemay 12-07-2020 06:17 PM

Straightwire, you seem to know what's what. Will the amp tend to run cooler running KT77 or KT66?, or EL34?

straitwire 12-08-2020 11:26 PM

Hey paulmlemay, If you run a tube with a lower filament current the unit will run cooler.
The filament current on the KT88 is 1.6 amps the KT77 is 1.4 amps and the EL34 is 1.5 amps.
The 6L6 is one of my favorites and draws .9 amps.
The 6V6 draws .45 amps.
The 6F6 draws .7 amps. (try some metal ones, you might like 'em)
Use 5U4 and 5Y3 rectifiers with the 6L6, 6V6, and 6F6.
And on a side note concerning rectifiers, the difference in voltage on the plates of the output tubes (B+) is a 5AR4 is around 35 volts higher than a 5U4 and a 5U4 is around 30 volts higher than a 5Y3.
The input tube plate voltage is regulated so it doesn't really change much (a couple of volts) when you change rectifiers.
Hope this info helps.

FloridaBoy 12-09-2020 07:27 AM

Quote:

Originally Posted by bearcity (Post 1023735)
The 6FLV is optimized for 6F6, 6L6 and 6V6 tubes but it can be run with any beam powered pentode. I have a new model 6V6er which is a 6FLV with a different PT. I like the lower power tubes the best in it but I like the lower power tubes best in all my Inspire amps (Custom Universal, PSE, and 6V6er).

I also have 3 Inspire Preamps. An LP-3a, Lp-27a and a new CJ5. I have bypassed the pre with my 6V6er in that it has a volume control but I have found it fatiguing. My ears seem to like the softer touch that Dennis's preamps offer. Like Florida says they are all very good but the CJ5 is a significant step up from the others. I have heard it head to head with the LP-3.1 as well and my feelings are the same about the CJ5 being superior.

What is the difference between the 6V6er and the Universal?

I prefer the lower power tubes too. However, KT88's in triode are sweet.

FloridaBoy 12-09-2020 07:54 AM

Quote:

Originally Posted by straitwire (Post 1024540)
Hey paulmlemay, If you run a tube with a lower filament current the unit will run cooler.
The filament current on the KT88 is 1.6 amps the KT77 is 1.4 amps and the EL34 is 1.5 amps.
The 6L6 is one of my favorites and draws .9 amps.
The 6V6 draws .45 amps.
The 6F6 draws .7 amps. (try some metal ones, you might like 'em)
Use 5U4 and 5Y3 rectifiers with the 6L6, 6V6, and 6F6.
And on a side note concerning rectifiers, the difference in voltage on the plates of the output tubes (B+) is a 5AR4 is around 35 volts higher than a 5U4 and a 5U4 is around 30 volts higher than a 5Y3.
The input tube plate voltage is regulated so it doesn't really change much (a couple of volts) when you change rectifiers.
Hope this info helps.

You could try a 5U4G or 274B with KT88's. That works for me with my triode strapped Inspire. The Tube Store has a Preferred Series 274B that is well liked. Old production, US made, 5U4G's won't break the bank.

bearcity 12-09-2020 07:56 AM

Quote:

Originally Posted by FloridaBoy (Post 1024566)
What is the difference between the 6V6er and the Universal?



I prefer the lower power tubes too. However, KT88's in triode are sweet.



As I understand it, Universal is a triode wire amp with opt NOT optimized for any given tube. 6V6er is Pentode optimized for tubes like 6v6, 6f6 and 6l6. The PT on the 6v6er is the significant difference from the 6flv. Dennis once told me the design changes but I do not remember them.

FloridaBoy 12-09-2020 08:51 AM

Quote:

Originally Posted by bearcity (Post 1024570)
As I understand it, Universal is a triode wire amp with opt NOT optimized for any given tube. 6V6er is Pentode optimized for tubes like 6v6, 6f6 and 6l6. The PT on the 6v6er is the significant difference from the 6flv. Dennis once told me the design changes but I do not remember them.

Thanks, a 6V6'er may be my next amp.


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