Dennis Had Inspire Amps

[FloridaBoy]

Originally Posted by Musica Amantem

I've read the max anode plate dissipation of the KT-88 is 42 watts, whereas the equivalent spec in the KT-66 is 50 watts. Does this mean that, other things being equal, the KT66 yields almost 20% more power? If so, why no Inspire amp comes stock with KT-66's? If so, maybe Dennis prefers the sound of the KT-88 over other kinkless tetrodes (KT-66, KT-77, etc.), but giving up an extra 2 watts or so in these amps is a tradeoff.

Yet, here's an argument which contradicts the above conclusion (from Wikipedia): "The KT88 was introduced by GEC in 1956 as a larger variant of the KT66. It was manufactured in the U.K. by the MOV (Marconi-Osram Valve) subsidiary of G.E.C, also labelled as IEC/Mullard, and, in the U.S., Genelex Gold Lion".

I'm assuming a "larger variant" means more power? Should we assume the larger the number after "KT" in their designation, the more power ceteris paribus?

Thanks for any enlightenment.

Dennis sold some amps with GL KT66's.

[FloridaBoy]

Comzee,

Where did you purchase the TS 6550's? If they are truly NOS they will need more hours to settle down. Be patient.

[x3workshop]

Just dropped a pair of NOS Mullard EL34 xf2's into my KT88 SE HO with a NOS Philco 5U4G BP. Not too shabby! Will have to leave these in for a couple weeks.

[Comzee]

Originally Posted by FloridaBoy

Comzee,

Where did you purchase the TS 6550's? If they are truly NOS they will need more hours to settle down. Be patient.

Ebay seller, said they were matched 105/105 on a Jackson 684s tester.
Here's a pic
Same seller has a 90/91 tested pair for $200.

Yea, I've only had them in for maybe 20 or so hours.
Also, does the ST shaped 6v6 apply over to these NOS 6550 regarding rectifier use?

I only ask because they crackle/pop in the first 5 minutes of amp power on.
I used a 274B which is directly heated, maybe not good for NOS?

[Bombadil]

Does your amp only crackle/pop with the TS 6550s? And this is using the same driver stage tube and rectifier as when used with other power tubes and there is no crackle/pop with them?

[Bombadil]

Originally Posted by Musica Amantem

Can anybody tell if the KT66 is detailed and transparent relative to other alternatives? Thanks!

I only ran my Genalex KT-66 tubes for a few hours in my amp, right now running the KT88s on a longer audition. However in those few hours the KT66 impressed with having very good detail, especially bass detail.

I evaluated two different brands of vintage 6V6, vintage Tung-sol 5881, new Genalex Gold Lion KT66, vintage Sylvania 6CA7, JJ KT77, new Genalex Gold Lion KT88. Out of this bunch, my two favorites were the KT66 & KT88.

For these evaluations I used a Sylvania bottom getter 6SN7 and a vintage 5V4 rectifier ... which just happened to be AA's favorite tubes in those positions in his listening sessions with Dennis about a week after I ran my comparisons. I also like these same tubes when used with a Preferred Series 274B rectifier.

[Bombadil]

Originally Posted by BearCityUSA

I asked Dennis about weather it was better to leave them on or turn off every evening and have the wear and tear of warm up. I have heard opposing arguments over the years. His response,"if you want your tubes to last longer, take them out of the socket and put them back in the box. They will last forever." He leaves his on 24-7.

I don't hear any difference between having them on for 15 minutes or having them on for 48 hours. So I don't see any reason to leave them on 24x7. They eat up electricity, heat my house when I have A/C on, and shorten tube life ... for no apparent benefit.

I ran mine for 2 days and took detailed notes as to how they sounded. Then turned it off until trannies & tubes reached room temperature. Turned it back on for 15 minutes, relistened to the same music. As far as I could tell, there was no difference.

[Comzee]

Originally Posted by Bombadil

Does your amp only crackle/pop with the TS 6550s? And this is using the same driver stage tube and rectifier as when used with other power tubes and there is no crackle/pop with them?

The answer to both those questions is yes/yes.

I've tried 274B, gz34 and just now 5v4. 6550 warm up pops using any of those.
Maybe not even 5 minutes, more like 2.5. Just until they get close to nominal temperature. Audio doesn't crack or pop, this is coming from the tubes themselves.

Same thing actually happens for 30 seconds after powering the amp off too, while they're cooling down they "pop" a few times. Audibly they seem to work as designed with no issues. idk?

[Bombadil]

And when you use your other power tubes, in the same configurations, they do not snap or pop?

This isn't a good thing from your TS 6550 tubes. Sometimes the noise can be from a bad driver stage tube, or dirty sockets or a bad solder joint. Or even a failing capacitor or resistor (which is highly unlikely in this case). But in the case of those things, it should be happening with all of your power tubes. If it happens only with the 6550s, then one (or both) of those tubes could be arcing / shorting. If it is just one of the tubes, then the noises should be coming out of just one channel / speaker.

If it is pinpointed to one of your 6550s, then that tube may have some life left in it, but it isn't a good sign at all. If the tube had any warranty / guarantee, I would return it. I recently tossed a vintage 6SN7 into the trash for having the same problem.

[Musica Amantem]

Originally Posted by Bombadil

I only ran my Genalex KT-66 tubes for a few hours in my amp, right now running the KT88s on a longer audition. However in those few hours the KT66 impressed with having very good detail, especially bass detail.

I evaluated two different brands of vintage 6V6, vintage Tung-sol 5881, new Genalex Gold Lion KT66, vintage Sylvania 6CA7, JJ KT77, new Genalex Gold Lion KT88. Out of this bunch, my two favorites were the KT66 & KT88.

For these evaluations I used a Sylvania bottom getter 6SN7 and a vintage 5V4 rectifier ... which just happened to be AA's favorite tubes in those positions in his listening sessions with Dennis about a week after I ran my comparisons. I also like these same tubes when used with a Preferred Series 274B rectifier.

Reason I asked is these are supposed to resemble the 6L6 family, which in my 6P3S-E version is the most detailed and balanced output tube I've heard in my system so far. The only area it comes relatively short is evidently in body and density of sound as well as the extra "oomph" from the larger KT88's, which sound also very neutral and nice but to me the density of the sound is veiling micro details slightly.