Dennis Had Inspire Amps

[BearCityUSA]

An interesting conundrum, to IIRPS or not to IIRPS? For me I guess it comes down to if it is a good value? I own a PSE with and a 2013 KT w/o so I do not have a real clear idea what the exact subjective auditory improvement is from the IIRSP or from the PSE circuit. I have a theory that a specific difference is a top end which is beyond any limit I have heard before. Certain high notes seem to go be completely unrestrained. Never heard such a thing from anything other than a live performance. Almost piercing but still pure. From Dennis' description of the improvement in somewhat technical terms, the root of my theory is based. (Sorry for the Yoda speak) I am curious what you that have had the mod could offer as to the difference between before and after. I look at the $350 recently quote for the cost as something that is likely a good value. Reflecting on the amount I have spent on tubes since getting my KT the mod cost is not that much. I know the Dennis upgrade from the LP-2 circuit to the LP-3a circuit was a good value. I don't know of any other audio upgrade for a similar price have had near the improved performance. Anyway, I look forward to more of you all's further analyses. I am torn. I do have a sense I will miss my tube rectification but maybe I would not care.

[Rosco65]

Bear,

I have the same two amps you do, with the same IIPS/non-IIPS status. The tubes I have in my KT88HO (GEC U52 rectifier, Voskhod 6N1P, Pope 6V6's) cost me more than the upgrade to IIPS would. I suspect that the PS upgrade may offer better sound per dollar than my fancy pants tubes. On the other hand, it may not be an either/or situation: the IIPS may make the great tubes even better.

[x3workshop]

Originally Posted by Rosco65

Bear,

I have the same two amps you do, with the same IIPS/non-IIPS status. The tubes I have in my KT88HO (GEC U52 rectifier, Voskhod 6N1P, Pope 6V6's) cost me more than the upgrade to IIPS would. I suspect that the PS upgrade may offer better sound per dollar than my fancy pants tubes. On the other hand, it may not be an either/or situation: the IIPS may make the great tubes even better.

Rosco65, I think your last statement hits it on the nose. It makes fancy pants tubes even better.

Here's how it applies to me - I don't have incredibly efficient speakers so that little extra cleanness when the amp is driven makes a difference to me and I hear it a moderate listening levels.

Everyone has a different system setup so it's really hard to quantify how much of a difference it will make, but it will be noticeable.

[BearCityUSA]

Well yea, likely no one on this thread will see it as an either IIRPS or more and better tubes. I only bring this up as a way to put the $350 into a different perspective.

Rosco,
i believe you were contemplating set up using 2 amps pushing 2 pair of Omega speakers, one facing the ceiling. Any progress?

[Rosco65]

Originally Posted by BearCityUSA

Well yea, likely no one on this thread will see it as an either IIRPS or more and better tubes. I only bring this up as a way to put the $350 into a different perspective.

Rosco,
i believe you were contemplating set up using 2 amps pushing 2 pair of Omega speakers, one facing the ceiling. Any progress?

I currently own three tube amps, one of which can be used without a preamp and two Inspire amps (KT88HO and PSE). I am planning with experimenting with the Omega speakers using the custom 421A amp, not the Inspires. The Inspire amps will be running either a pair of Omega Super Alnico's and/or set of Altec 414A/802D/32A speakers that can be biamped if necessary.

As simple as this hobby can be, it has become increasingly more complicated as I play with options. I have two rooms that can accommodate two-channel systems: A small dedicated listening room that currently houses Omega Super Alnico's and which will ultimately house the custom Altec-based system. I also have a larger (but still modestly sized) living room that has a decent but not great HT system. I would also like to have a tube based listening system in this room as well.

Here are my current components:

1. Kenwood KD550 turntable with Nagaoka cartridge. Currently using a Superphon preamp as phono stage. Awaiting the day when Dennis makes one available.
2. Schiit Bifrost Multibit DAC.
3. DB Audio Labs Tranquility DAC.
4. DB Audio Labs Tranquility SE DC.
4. Inspire LP-27a preamp.
5. Inspire KT88HO amp.
6. Inspire PSE amp.
7. Custom SE 421A amp using the Fi circuit and Hashimoto output transformers.
8. Omega Super Alnico Monitors with Skylan Stands.
9. Omega wide baffle Super 3's with RS5 drivers.
10. Second set of RS5 drivers and a smaller vented enclosure into which they will work.
11. Altec 614 cabinets.
12. One pair of Altec 414-8C alnico drivers.
13. Two pair of Altec 414A alnico drivers.
14. One pair of Altec 802D (8ohm) with GPA diaphragms.
15. One pair of Altec 32A horns.
16. NOS Gudeman PIO capacitors for Altec crossovers.
17. Werner Jagusch autoformers for Altec crossovers.
18. WE 14 ga. and SUpra speaker wire.
19. Zenwave audio interconnects.
20. Various stands, supports and Isoacoustics isolation products.
21. About $2,000 of NOS and vintage tubes for all three amps.
22. EDIT: pair of Goodmans 12" Triaxiom 16 ohm coaxial drivers with matching ARU aperiodic vents.

As you can imagine, putting together this jigsaw puzzle of current and vintage components into two or three quality systems will take some trial, error and experimentation, not counting the amount of possible tube-rolling. And while my SO is understanding and enthusiastic about quality music reproduction, there still remain the constraints of domestic acceptability.

[x3workshop]

Originally Posted by Rosco65

I currently own three tube amps, one of which can be used without a preamp and two Inspire amps (KT88HO and PSE). I am planning with experimenting with the Omega speakers using the custom 421A amp, not the Inspires. The Inspire amps will be running either a pair of Omega Super Alnico's and/or set of Altec 414A/802D/32A speakers that can be biamped if necessary.

As simple as this hobby can be, it has become increasingly more complicated as I play with options. I have two rooms that can accommodate two-channel systems: A small dedicated listening room that currently houses Omega Super Alnico's and which will ultimately house the custom Altec-based system. I also have a larger (but still modestly sized) living room that has a decent but not great HT system. I would also like to have a tube based listening system in this room as well.

Here are my current components:

1. Kenwood KD550 turntable with Nagaoka cartridge. Currently using a Superphon preamp as phono stage. Awaiting the day when Dennis makes one available.
2. Schiit Bifrost Multibit DAC.
3. DB Audio Labs Tranquility DAC.
4. DB Audio Labs Tranquility SE DC.
4. Inspire LP-27a preamp.
5. Inspire KT88HO amp.
6. Inspire PSE amp.
7. Custom SE 421A amp using the Fi circuit and Hashimoto output transformers.
8. Omega Super Alnico Monitors with Skylan Stands.
9. Omega wide baffle Super 3's with RS5 drivers.
10. Second set of RS5 drivers and a smaller vented enclosure into which they will work.
11. Altec 614 cabinets.
12. One pair of Altec 414-8C alnico drivers.
13. Two pair of Altec 414A alnico drivers.
14. One pair of Altec 802D (8ohm) with GPA diaphragms.
15. One pair of Altec 32A horns.
16. NOS Gudeman PIO capacitors for Altec crossovers.
17. Werner Jagusch autoformers for Altec crossovers.
18. WE 14 ga. and SUpra speaker wire.
19. Zenwave audio interconnects.
20. Various stands, supports and Isoacoustics isolation products.
21. About $2,000 of NOS and vintage tubes for all three amps.

As you can imagine, putting together this jigsaw puzzle of current and vintage components into two or three quality systems will take some trial, error and experimentation, not counting the amount of possible tube-rolling. And while my SO is understanding and enthusiastic about quality music reproduction, there still remain the constraints of domestic acceptability.

I think you have quite a pleasant puzzle solving task ahead. I'd love to be able to hear some of the combinations of those components. Especially the loudspeakers.

How long did it take you to acquire that specific collection of components? Curious what your upgrade & evolution path was.

I'm blessed/cursed to have very limited space for gear as I live in a 950 sq ft apartment with my 12 year old son. Having said that, I've gone amp crazy.

Current component collection:

1. McIntosh C100 Preamp Controller
2. Bryston BP-25 Preamp
3. Inspire LP-27a Preamp
4. Inspire KT88HO SE w/IIPS upgrade
5. HK Citation II (currently on my bench)
6. McIntosh MC225 (rebuilt)
7. 2 x McIntosh MC240's monbloc setup(rebuilt)
8. 4 x McIntosh MC30's Biamp setup(rebuilt)
9. 4 x Heathkit UA1/2 Biamp setup (substantial upgrades & true giant killers)
10. Schiit Bifrost Multibit DAC
11. Oppo BDP 105 Universal player/DAC
12. Sony XF1 HD Tuner w/xdrguy mods
13. QNap Network Server
14. ML Electro Motion ESL's
15. Rega R7 Transmission Line
16. Desopren Systems folded horns w/Frazier & Morel drivers
17. ML Dynamo 700sub
18. Close to 3000 New, NOS & Vintage Vacuum tubes - too many
**No room for vinyl

I have 2 systems setup, one in the living room and one in my bedroom. I use both systems almost every day and rotate the amps based on any number of irrational or rational reasons and mood swings. Surprisingly, my space isn't cluttered and 12' high ceilings help with this feeling (and sound).

I love all the gear and have tuned the sound to my tastes, but am going to de-amp relatively soon. Same for the tube collection. I'll keep the prime glass to last the rest of my life (and my son's) and sell the rest next year. I've never liked owning too much stuff. It's like being overweight, you lose your agility.

OK, enough OT rambling

[Rosco65]

X3,

I edited my post to include the pair of Goodmans Triaxiom 212C drivers and ARU's. They are alleged to go head to head with Altec 414's, but need an even bigger even when equipped with the ARU's. They need 7,800 cubic inches with the ARU's and 11,200 without. They do, however, give better bass than the Altecs.

I'm in a tiny ranch house in a close in NYC suburb of about 800 square feet. My listening room is about 140 sqwuare feet and the living room is an open space of 15 x 22 feet with vaulted 12 foot ceilings.

The living room has a media wall, painted dark gray with a 65 inch TV and wall mounted shelves in a console arrangement. A Marantz 7.2 receiver feed GR Research front and center speakers and two pairs of Audioengine P4's serve surround duties. Two Dayton Subs from Parts Express fill out speaker duties. Sources include an Xbox One S, Mac Mini running Tidal and Roon into either the Marantz or into the Schiit DAC. I can also use Airplay to stream to the Marantz.

I just brought in the Altec 614 cabinets into the living room. They slide perfectly into the media wall with 1/2" to spare and when raised to the appropriate height will blend nearly seamlessly into the wall shelves. I have options in how to drive them: They can be fed completely separately by the 421A amp directly from the DAC connected to the Mac Mini or they can be driven by the two-channel pre outs of the Marantz, which means I can use a "spare" Inspire amp to drive them while still using the "easy" system in the living room.

I can load the 614's with Altec 414A's (99dB) or 414-8C's (96dB). Both will run out to 3-4kHz with no crossover. I will then need something for high frequencies. If I use 414A's, a horn and 802D driver would be necessary. If I use the 414-8C's, I think I could get away with using a spare pair of Omega RS5 4.5" drivers (94.5dB) cut it with a single 3.3uF cap at 6kHz or so. I would need to make a pod to top mount either option.

[Bombadil]

No serious power tube rolling as yet, but over the past 14 days I've run the amp with new Gold Lion KT88, Tung-sol KT120, Russian 6P3S-e, Gold Lion KT66, and JJ KT77. All of this in my new apartment and through my Von Schweikert tower speakers. The VS speakers are too big for this space, but as I'm the only one living here, that's the way it is going to be.

All of these tubes have sounded fabulous. The amp melds so well with these speakers. Many would consider my system to be underpowered, as the speakers are spec'ed at 91dB. But there is no sense of this at all. I have a 260 wpc SS amp and, at my listening levels, there is little discernible difference in power. If I jack the volume up to where it is too loud for me, the Inspire runs out of steam on deep base notes, and I'm sure there is some clipping on peaks. But even at what I consider to be pretty loud, the amp does great.

I'm sure I'll be able to discern some differences between the power tubes (I did before when I was driving Focal Aria 906 monitors) but I'm thoroughly enjoying all of them. Right now enjoying female jazz vocals & using the KT77s. Beautiful.

[Analog Addict]

Originally Posted by x3workshop

I think you have quite a pleasant puzzle solving task ahead. I'd love to be able to hear some of the combinations of those components. Especially the loudspeakers.

How long did it take you to acquire that specific collection of components? Curious what your upgrade & evolution path was.

I'm blessed/cursed to have very limited space for gear as I live in a 950 sq ft apartment with my 12 year old son. Having said that, I've gone amp crazy.

Current component collection:

1. McIntosh C100 Preamp Controller
2. Bryston BP-25 Preamp
3. Inspire LP-27a Preamp
4. Inspire KT88HO SE w/IIPS upgrade
5. HK Citation II (currently on my bench)
6. McIntosh MC225 (rebuilt)
7. 2 x McIntosh MC240's monbloc setup(rebuilt)
8. 4 x McIntosh MC30's Biamp setup(rebuilt)
9. 4 x Heathkit UA1/2 Biamp setup (substantial upgrades & true giant killers)
10. Schiit Bifrost Multibit DAC
11. Oppo BDP 105 Universal player/DAC
12. Sony XF1 HD Tuner w/xdrguy mods
13. QNap Network Server
14. ML Electro Motion ESL's
15. Rega R7 Transmission Line
16. Desopren Systems folded horns w/Frazier & Morel drivers
17. ML Dynamo 700sub
18. Close to 3000 New, NOS & Vintage Vacuum tubes - too many
**No room for vinyl

I have 2 systems setup, one in the living room and one in my bedroom. I use both systems almost every day and rotate the amps based on any number of irrational or rational reasons and mood swings. Surprisingly, my space isn't cluttered and 12' high ceilings help with this feeling (and sound).

I love all the gear and have tuned the sound to my tastes, but am going to de-amp relatively soon. Same for the tube collection. I'll keep the prime glass to last the rest of my life (and my son's) and sell the rest next year. I've never liked owning too much stuff. It's like being overweight, you lose your agility.

OK, enough OT rambling

Funny how this topic has come up. During the tail end of my afternoon session with Dennis last Friday, we spent a lot of time talking over the music, over an hour and a half of serious heat to heart discussion. One of the topics we discussed was my collection of audio gear and how at this point (with his help and guidance) I can build equipment that sounds better than any of this TOTL vintage gear. I sold my MC 225 not too long ago, and will most likely liquidate almost all of my acquired equipment. I have a bunch more Mc gear, and the complete H/K Citation series (I-V), plus a number of Altec amps, Dynaco Mk VIs, etc. I will prolly keep a few of the high output pieces, but unless I were to rebuild the vintage pieces completely, with all new passive components, I could never have the complete reliability I have with my own custom built from the ground up amps and pre amps. Plus the sound is sublime, better than anything I've heard out of the vintage pieces. Yeah, I prolly won't get the amount of cash for one of my amps that I could for my pair of MC 75s or Cit II, but what exactly is the goal here?

[Bombadil]

Over this past year I considered purchasing any number of classic amps. I do like many of them. But I backed off on several Mc's, Cit II, various ST70 riffs, and more because I just wasn't convinced that any of them would sound as good as these modernized SE amps. Why drop $3K or more on an amp which I would probably not use much?

Now if I was going to spend $10K+, I'd certainly look at other newer production amps. But I believe I've left my desire for the vintage stuff behind me.