Dennis Had Inspire Amps

[cgn-dt-n]

Oh it's cute, the little GK6 with the globe rectifier looks nice. if it has a similar sonic signature as Dennis' other devices, then that's definitely a big hit.

[Isaacc7]

I’m curious if Dennis uses the same output transformers for the 6k6 amp as the Firebottle kt88. Does he have a bunch of transformers he chooses from or has he standardized on just a few?

[Analog Addict]

Originally Posted by Isaacc7

I’m curious if Dennis uses the same output transformers for the 6k6 amp as the Firebottle kt88. Does he have a bunch of transformers he chooses from or has he standardized on just a few?

That falls back into the tube theory domain. Different output tubes need output transformers (OPT) of different impedance to match their electrical characteristics. A 6GK6 will require a very different OPT than a KT-88. However, a family of tubes like the 6V6/6L6/6550/KT-88 etc can all use the same OPTs if the tube itself can handle the typical operating points of the amp. That's why you would usually change rectifiers when changing output tubes in some of Dennis' amps.

For example, the KT-88 can handle more plate voltage than a 6V6G. So, if you use a rectifier that drops a lot of voltage, like a 5R4, the 6V6G will be happy. If you use a 5AR4, (which drops the least voltage of standard rectifiers) with 6V6Gs, you may wind up buying new tubes. Instead, use the 5AR4 with KT-88s and up.

All in all, I think Dennis uses at least seven different OPTs due to the wide variety of output tubes in his designs....

[Analog Addict]

One quick note on the GK6'er - Dennis just informed me that it will come stock with a globe 80, since this is the rectifier tube that he likes best.

[kd4ylq]

Did you buy the parts alone from Dennis and build it yourself?

[Analog Addict]

Originally Posted by kd4ylq

Did you buy the parts alone from Dennis and build it yourself?

Yes and no. Dennis is busy filling orders, so besides supporting him as best I can, I spend my time fooling around with tubes and designs to see what sounds good and what might catch Dennis’ fancy. The 6GK6 prototype was built from a chassis that Dennis rejected because the manufacturer didn’t weld the seams. The iron was sourced from Inspire stocks so that if Dennis liked what he heard, he wouldn’t have to chase weird or unobtainium transformers. Most everything else like sockets, caps and resistors were out of my stock/parts bin.

I’m working on finalizing a PSE GK6’er design as to be able to see what it might be capable of, although my power supply won’t be commercially viable. I want this next amp to light up like the Vegas strip at night, so I’m gonna use some bright blue Hg rectifiers and a number of VR glow tubes. Call it a proof of concept if you will…

[kd4ylq]

I'm a newbie here so I don't know anything about your connections with DH, but you seem to be a dyed-in-the wool DIYer like myself, and audio enthusiast as well (it should go without saying). I met Dennis at the DurHAMFEST back around 1998 when he came to my table and (among other things) told me that Hams can't, won't or don't appreciate good sound. I thought it strange for him to say that (and still do) but heck it was just his opinion at that moment. I'd love to put together one of his KT88 SE amps myself - do you think he'd consider selling one in DIY form? I'm very experienced and punctilious in electronics construction (HV especially).

[Showme]

Allan, I'm anxious to see your new design. The light show should be great. Match that with the sound and wow!

[Analog Addict]

Originally Posted by Showme

Allan, I'm anxious to see your new design. The light show should be great. Match that with the sound and wow!

Heh, well don’t get your hopes up too much. Talk is cheap, but I do have one great advantage and that is an excellent tutor. Also, I can’t build an amp in an afternoon either, and given all my commitments this month it will be a slow process. However, it anyone is interested, I can post the build here instead of Audiokarma like I usually do…

[Analog Addict]

Originally Posted by kd4ylq

I'm a newbie here so I don't know anything about your connections with DH, but you seem to be a dyed-in-the wool DIYer like myself, and audio enthusiast as well (it should go without saying). I met Dennis at the DurHAMFEST back around 1998 when he came to my table and (among other things) told me that Hams can't, won't or don't appreciate good sound. I thought it strange for him to say that (and still do) but heck it was just his opinion at that moment. I'd love to put together one of his KT88 SE amps myself - do you think he'd consider selling one in DIY form? I'm very experienced and punctilious in electronics construction (HV especially).

Dennis reads every post in this thread, so I’m sure he will provide an answer one way or another