Dennis Had Inspire Amps

[bwilson51]

I am running Gold Lion KT-66’s with 6sn7’s and a 5y3 and that combination sounds the best. I have also used KT-88’s with sovtek 5ar4 and the amp chassis was hot to the touch with them to.

[sfleming]

I've got a 5y3 coming, and am also looking online for some 6v6gt for now.
Hey dumbish question for the PSE owners: I know I can mix in different tube types in this. Anyone have some favorite combos they'd like to share ?
Also, I know there's comments in the thread of people having a lot of sonic changes as a result of rectifier swaps, but maybe not so for the PSE w/diodes in the rectification stage like I have. Does that sound about right ? I've tried contacting Dennis via Ebay messaging on a couple topics but he's clearly busy.

[Bombadil]

Have been doing a lot of tube rolling, testing, and reconfiguring during the safer at home period. Have had a lot of fun.

Continuing to play around more with my Inspire SE EL84. Moved it into my bedroom, 12' x 12', where I don't need a lot of power and I don't tend to play music as loudly there. I'm driving Focal Aria 906 bookshelf speakers, spec'ed at 89.5db but which measure at 87.5. The Focals received very positive reviews from The Absolute Sound, What Hi-Fi?, and Soundstage.

Normally I wouldn't think to drive a speaker like this with just 4-5 wpc, but it works nicely. When I tried the same pairing in my large living room a few years ago, it failed, with the Inspire frequently going into clipping on low bass notes. In my smaller bedroom and positioned closer to walls, the bass is surprisingly full and satisfying.

While tube rolling, I found a new favorite, the new production Genalex Gold Lion EL84. I have a number of vintage and new EL84/6BQ5, some which fetch fairly high prices when they are real NOS. I haven't finished my comparisons in my new setup, but so far I'm really liking these new tubes.

I also found that I get a fuller bass when using a 5U4GB rectifier as compared to a 5Y3 or 5V4GA. I know the 5U4GBs are rated to provide more voltage and current, so I guess that isn't a big surprise, but at times with some tubes I perceived that there was a little more goodness/sweetness with the 5V4GA. With the Gold Lion EL84 I don't hear that difference, the 5U4GB matches the tonality while providing more bass.

Just finished listening to Linda Ronstadt, beautiful vocals, nicely balanced bass without that annoying mid-bass boominess, and good detail & imaging on highs without being harsh. Very pleasant.

[bwilson51]

I need to try my 5u4 tubes, I have really been enjoying my kt-66’s with a 5y3 rectifier tube.I am going to try the 5u4 and see if the bass response is deeper.

[Rosco65]

Originally Posted by sfleming

I've got a 5y3 coming, and am also looking online for some 6v6gt for now.
Hey dumbish question for the PSE owners: I know I can mix in different tube types in this. Anyone have some favorite combos they'd like to share ?
Also, I know there's comments in the thread of people having a lot of sonic changes as a result of rectifier swaps, but maybe not so for the PSE w/diodes in the rectification stage like I have. Does that sound about right ? I've tried contacting Dennis via Ebay messaging on a couple topics but he's clearly busy.

I own one of the first PSE’s. As soon as it arrived I sent it back for the then-new IIPS mod. I did not listen to the amp prior to installation of the IIPS.

During transients the four output tubes of the amp can draw quite a bit of current. This can cause a momentary drop in B+ voltage. A rectifier tube is good for smoothing this transient and providing good overload characteristics. However, this imperfect rectified DC plays havoc on the grid supply. Even with the zener diode string we experience some unwanted ripple/distortion, which gets magnified at the output.

Dennis’s IIPS mod replaces the rectifier tube in the circuit with SS diodes. This provides more instantaneous current, at the expense of “tube sound”. The rectifier tube is relocated in the fire unit to the grid supply. It now serves as the first [tube] diode in the regulated PS string. It now functions as a DC-DC rectifier, further smoothing the grid supply while buffering it from changes in the B+ supply. Additionally, we would expect to see some tube buffering of the B+ supply from the tube as well.

I do hear changes in rectifier tubes in my amp. It will not be as dramatic as it would be without the IIPS, but it is appreciable. One point to remember is that the rectifier tube is no longer passing a lot of current, and some tubes may sound better coasting along than others.

[FloridaBoy]

Originally Posted by Rosco65

I own one of the first PSE’s. As soon as it arrived I sent it back for the then-new IIPS mod. I did not listen to the amp prior to installation of the IIPS.

During transients the four output tubes of the amp can draw quite a bit of current. This can cause a momentary drop in B+ voltage. A rectifier tube is good for smoothing this transient and providing good overload characteristics. However, this imperfect rectified DC plays havoc on the grid supply. Even with the zener diode string we experience some unwanted ripple/distortion, which gets magnified at the output.

Dennis’s IIPS mod replaces the rectifier tube in the circuit with SS diodes. This provides more instantaneous current, at the expense of “tube sound”. The rectifier tube is relocated in the fire unit to the grid supply. It now serves as the first [tube] diode in the regulated PS string. It now functions as a DC-DC rectifier, further smoothing the grid supply while buffering it from changes in the B+ supply. Additionally, we would expect to see some tube buffering of the B+ supply from the tube as well.

I do hear changes in rectifier tubes in my amp. It will not be as dramatic as it would be without the IIPS, but it is appreciable. One point to remember is that the rectifier tube is no longer passing a lot of current, and some tubes may sound better coasting along than others.

I find that to be the case with my PSE too.

[FloridaBoy]

Originally Posted by sfleming

I've got a 5y3 coming, and am also looking online for some 6v6gt for now.
Hey dumbish question for the PSE owners: I know I can mix in different tube types in this. Anyone have some favorite combos they'd like to share ?
Also, I know there's comments in the thread of people having a lot of sonic changes as a result of rectifier swaps, but maybe not so for the PSE w/diodes in the rectification stage like I have. Does that sound about right ? I've tried contacting Dennis via Ebay messaging on a couple topics but he's clearly busy.

The Winged C's are well regarded. So, tune them to taste with the input tube and rectifier. I tried mixing power tubes EL34 & 6L6 etc....nah and meh.

Personally, I like 6L6G's and the Pope 6V6GT's with a 5Y3 in my IIPS PSE. The Pope tubes are pretty expensive now but I've had these for many years. The amp runs warm with these tubes. Not at all hot.

The new Tung Sol and Gold Lion 6V6GT's are quite clean and modern sounding.

You can go nuts rolling power tubes in these amps. The input tube has a LARGE impact on the sound.

[sfleming]

That reminds me I need to check and make sure I still have those 6n1p.

Stereo sounds great at the moment but I've not been able to get back to a position where I like my Lowthers again. I used to like them pretty well with my 2a3s, but I got restless and I could never get my amps down to hum silent, so I took those amps apart and so on. I learned long ago that I like tinkering around with this stuff about as much as I like listening to music.

Anyway, right now using some old GR Research standmounts and subs. I need to get my a/d/s 810s back from my buddy at some point I bet they'd sound great with these amps. Also have those Heresy Is in the wings that are itching for a chance to be wired up.

[Analog Addict]

Dennis has been busy...

Untitled by Allan Shang, on Flickr

New 6V6'er running some 8417s I brought over...

Untitled by Allan Shang, on Flickr

And running some US made WE 350Bs sent in by a customer...

Untitled by Allan Shang, on Flickr

A mirror image set of QMBs running metal 6F6s

Untitled by Allan Shang, on Flickr

Untitled by Allan Shang, on Flickr

A new fresh off the bench pre amp, tentatively named the CJ5 since it will run both 6C5s and 6J5s...

Untitled by Allan Shang, on Flickr

Untitled by Allan Shang, on Flickr

Untitled by Allan Shang, on Flickr


And lastly, the mythical Inspire phono pre amp...

Untitled by Allan Shang, on Flickr

[FloridaBoy]

WE 350B's? At $2K+ a pair I'd have to sell both kidneys. So, I'll have to pass. What's the story on the 6V6'er Very cool amp.