[straitwire]

Hey roscoe65, I modify/upgrade my amp to the latest circuit that we're building so Dennis and I can discuss it's performance and characteristics.
 I like the IIPS and I've switched back and forth several times.
 

[roscoe65]

Would you characterize the IIPS as a worthwhile upgrade?

Could you relay your experiences with the different circuits?

Thanks,
R

[straitwire]

My experience with all of these circuits is that they all sound different but saying one is "better" than another or is an "upgrade" really isn't the way to look at it.
 I like to use the ice cream analogy.
 The flavors I like may not be the ones you like but as a new flavor is introduced one could say it's "better" to them than another.
 This is subjective so I have to choose my words carefully.
 I have listened to just about all of Dennis's designs, and some of them work well with my system and some not so much, but only in presentation not sound quality.
 As for me, I tend to prefer Pentode operation over strapped Triode.
 But having said that, I appreciate strapped Triode's midrange presentation.
 The midrange "hump" from strapped Triode can bring voices and solo instruments to the front, producing more intimacy with singers or instruments.
 Pentode operation tends to produce more articulate lower midrange and bass, and puts things in there "place".
 But once again this is subjective and depends on a lot of different factors.
 Your choice of music, your system, your room, your preferences, and too many other factors to list here.

 To answer your question about updates (I really shouldn't call them upgrades), Dennis is really busy building amps and many of these updates require tearing down the unit and that just isn't practical.

Sorry to be so long winded.
If you have any more questions or if I haven't fully answered your questions let me know.
 

[ilikerecords]

Trying to get in touch with you @straitwire.

[straitwire]

Hey ilikerecords, whatsup?

[ilikerecords]

Hey ilikerecords, whatsup?

I've messaged you.  Was just giving you a heads up.

[ilikerecords]

I give up.

[BearCityUSA]

I give up.

Straitwire went and got himself a day job.🤪 not sure how often he checks these threads. I’ll nudge him and see if I can get you a response.

[Tom Bombadil]

A post I may published elsewhere:


We switched to the KT88 SET (triode) amp next with the KT170s.  BTW, same OPTs in both amps I was told. I will preface this with this statement. I have yet to meet a pair of KT 88/120/150s I cared for. I know there are many out there who love this class of tube but I always seem to prefer the 6f/l/v6 Pentodes. The KT 170s are the same for me. I switched them out for a pair of 6f6g from the mishmash of tubes there on the coffee table.  There was the sound I know so well and absolutely love from my other Inspire amps (custom Universal, PSE, and 6V6er). d they each had to get home to their families.

To clarify, you found the KT170 to sound very similar to the KT88 / KT120 / KT150 family of tubes?

That's what others have told me.   I own GL KT88, TS KT120 and TS KT150.   There are some subtle differences, but I find all three of these to sound more alike than different in my Inspire KT88 HO and in my Inspire PSE.  I never popped for KT170 and now a quad of them costs a small fortune.  I just didn't have faith that they would sound all that different and they would produce no extra power in either amp. 

[Opus Flatus]

I think you're spot on about the KT 170. If you like KT 88 strapped in triode or single-ended, then the KT 170 gives you a wee more bloom, imaging, and space (insert your favorite adjective) IMHO. It was an excellent option but not at these current prices. I got mine pre-sanctions at $170 for a matched pair. Even at the presanction price, I would argue they are overkill for my Universal Amp. Prior to the KT 170's, I rolled in a pair of KT 120's which were similar as I would imagine the KT 150's would be. The upside is that these tubes will last a long time in an Inspire amp. They are not run all that hard in comparison to their rated output.

[Tom Bombadil]

I was fortunate to pick up some slightly used (roughly 150-200 hours claimed) KT120 and KT150 after they had been used at an audio show.  This was last year.  $30 each for the KT120, $40 each for the KT150.  They tested & looked new. 

I like both types.  Not as warm or midrange sweet as some other tubes but big open soundstage, neutral and well-defined with the strongest, clear bass I've heard from any tube in my gear.

[Opus Flatus]

You got an excellent deal, especially on the KT150's. I would agree with your experience with the KT 120 tube; I'm a big fan of the 88 series tubes -big tube = big sound.

[Tom Bombadil]

Another tube I really like in both of my Inspire amps is the Gold Lion KT66.   It produces a punchier, more dynamic sound.  I've liked all of the 6L6-type tubes I've used, this one is my favorite of that group.   While some always favor vintage, and for good reason, the Russian factories do a good job on 6L6 tubes.  The Tung-sol 7581a & KT66 are both very good and the GL KT66 (which is significantly different from the T-S) is better yet, IMO. 

I've read posts from three or four long-term and well-regarded tube amp builders who all sang the praises of the new production Russian 6L6-types.  Saying that on their test gear and to their ears, they are right there with the vintage GE and other old production.

Several Inspire owners prefer the smaller 6V6, and even 6F6.  I have several of each and I find them to be fine tubes which produce a pleasant sound, but they don't sound as "magical" to me as they seem to do for others. 

[Opus Flatus]

I rolled in some NOS RCA metal can 6L6's and they were very good. I have also tried some metal can 6F6, also a sweet-sounding tube.  I preferred the 6L6 over the 6F6; especially when driving my speakers full range (GR Research NX Studio Monitors).

Since I listen mostly nearfield I prefer the larger pentodes when listening in full range. Crossed over to subs; I find it doesn't matter much which tubes I roll in. I also have a pair of the original Soundfield Monitors, with KEF COAX's built-in sealed subs. Any tubes I roll in with these speakers sound great.