Dennis Had Inspire Amps

[x3workshop]

Absolutely, but I do think power tubes become a part of the varying speaker impedance, damping, OT equation. I could be wrong.

[Musica Amantem]

Right. I think the only reasonable way for me to decide if the KT-150 may be a good option in my case would be to know what other tube type you preferred (or still prefer) before trying the KT-150's. For example, KT-66, KT-77, 350B, 6L6 variants, etc. The idea is to anticipate the effect of the KT-150 based on your rig and my familiarity with those other more likely tube candidates in my rig. Thanks so much for your patience.

[x3workshop]

Originally Posted by Musica Amantem

Right. I think the only reasonable way for me to decide if the KT-150 may be a good option in my case would be to know what other tube type you preferred (or still prefer) before trying the KT-150's. For example, KT-66, KT-77, 350B, 6L6 variants, etc. The idea is to anticipate the effect of the KT-150 based on your rig and my familiarity with those other more likely tube candidates in my rig. Thanks so much for your patience.

Hard to answer really.

Well, pre IIPS, I was going between A) RCA 807's matched with an RCA VT-229 and an RCA 5U4G, and B) GL KT88's with a Sylvie 6SN7GT and Mullard 5AR4 and C) Amperex EL34's with the VT-229 and the 5AR4.

The 807's are a very nice tube for this amp with solid bass, good mids and not too shiny HF and a nice overall airiness. Excellent overall balance. I like this very much, but...

The KT88 setup had better overall top to bottom performance with great detail, staging, dynamics and authority. My favorite setup.

The EL34 setup was a very strong - really shines in the vocal department with a sweet, not too forward midrange and a nice top end. Just not as much oomph in the low end and maybe just a bit lazy.

Post IIPS, I would say the KT88, Sylvie 6SN7GT and 5R4GY rectifier has been stellar in all respects. I tried the Amperex EL34 setup, and it was very good as well. The 807's still come in second, but liked the KT88's best. I do need to try more combos with the PS upgrade. I just haven't had that much time with it.

I will try other driver combos with these KT150's to see if I can tailor the sound a bit more.

I have rolled and rolled. Some only briefly, and others for a good amount of time. If I like the sound initially, I will leave them for a few weeks at least to get a good overall feel before moving to something else.

6V6 - Pope, RCA, GE, TS, and the odd Westinghouse. Nice balanced sound, but lacked the drive, control and authority I like.

EL34's from Mullard, Tele and Sylvania 6CA7's all sound equally nice along with new GL KT77's - a very nice tube! I need to give the KT77 more listening in the future. I like this power tube in the amp.

6L6GC's including NOS RCA Blackplates, GE, Winged C, New Issue Tung Sol 6L6G's, and RCA 807's. I like the 807's at lower listening levels as they have a slightly fatter sound.

GL KT66 is really nice, but I haven't given them enough time to form a good opinion.

Vintage Tung Sol 6550's are great - along the same lines as the GL KT88's, maybe better.

TS KT120's are a very good tube - somewhere between the KT88 and a 6L6GC in sound sig, but they can be overly harsh if driven hard. No special magic for me here, but a good everyday tube.

All of the above were used with:

Rectifiers - 5U4/GZ34/5R4/5Y3/80/5V4, etc

6SN7 Drivers - Vintage TS blacks , Sylvie Chrome domes/Sylvie 3 hole/RCA BP's/RCA VT-231/GE/CBS/Reissue TS/Shuguang CV-181

6SL7 - RCA VT-229/ RCA Blackplates/Sylvies/GE's/CBS


Have I confused you? Having looked at all the tubes I've run, I'm a bit confused! I'll be editing this post, I'm sure.

[Musica Amantem]

x3workshop: No confusion here, I think you have pretty much covered the entire range! Interesting to see how I share your impressions on the 6V6's and KT-77's. I believe you should give the KT-66's some listening attention, as these are quite balanced and sound excellent, especially with a 274B (5U4G).

In my experience, the KT-88's are very musical, offering great body of sound but masking some detail through its boldness. On the other extreme, the 6V6's are just anemic. The 6L6 (6P3S-E variant) was my favorite until I tried the KT-66 and KT-77, with the latter particularly interesting in the mid-range at the expense of some loose bass (not unlike the El34 signature).

In this picture, I don't see how the powerful KT-150 would fit, yet. Although I have no IIPS mod in mine, my speakers are nominally 98 dB /1 W/1 M, so in my smallish listening room it is likely I'll never be getting close to clipping, therefore the power mods are not too appealing to me.

I'm about to try the VA 350B and VA 6550 for the first time this week-end and then I'll have a more informed view of the range in my rig, except for the "extreme" KT-150. The 807 are not well reviewed for audio applications according to some stuff I read somewhere. Evidently that's not the case in your experience, so that's another possibility.

You seem to prefer the boldness in output tubes, and it is probably due to your special system settings, which are quite different to mine. This may explain your inclination to the KT-150. In my case, KT-66 and KT-77 (with their inherent tradeoffs) are the best because these combine the good things of the KT-88 without any of its drawbacks, but that is in my system so YMMV. All the cited impressions are based on the use of the LP-27a preamp combining 56's and 27's depending on the output tubes in the amp. Thanks so much for your kind support!

[x3workshop]

Originally Posted by Musica Amantem

x3workshop: No confusion here, I think you have pretty much covered the entire range! Interesting to see how I share your impressions on the 6V6's and KT-77's. I believe you should give the KT-66's some listening attention, as these are quite balanced and sound excellent, especially with a 274B (5U4G).

In my experience, the KT-88's are very musical, offering great body of sound but masking some detail through its boldness. On the other extreme, the 6V6's are just anemic. The 6L6 (6P3S-E variant) was my favorite until I tried the KT-66 and KT-77, with the latter particularly interesting in the mid-range at the expense of some loose bass (not unlike the El34 signature).

In this picture, I don't see how the powerful KT-150 would fit, yet. Although I have no IIPS mod in mine, my speakers are nominally 98 dB /1 W/1 M, so in my smallish listening room it is likely I'll never be getting close to clipping, therefore the power mods are not too appealing to me.

I'm about to try the VA 350B and VA 6550 for the first time this week-end and then I'll have a more informed view of the range in my rig, except for the "extreme" KT-150. The 807 are not well reviewed for audio applications according to some stuff I read somewhere. Evidently that's not the case in your experience, so that's another possibility.

You seem to prefer the boldness in output tubes, and it is probably due to your special system settings, which are quite different to mine. This may explain your inclination to the KT-150. In my case, KT-66 and KT-77 (with their inherent tradeoffs) are the best because these combine the good things of the KT-88 without any of its drawbacks, but that is in my system so YMMV. All the cited impressions are based on the use of the LP-27a preamp combining 56's and 27's depending on the output tubes in the amp. Thanks so much for your kind support!

I'm sure my current affinity for the 150's is due to the loudspeakers I'm using and the McIntosh C100A pre. I have not tried these tubes with the LP-27a. I know the sound will be very different when I do. I may not like it so much.

The 807 is a nice tube - essentially a 6L6 with a top cap config. The RCA blackplate version is inexpensive so I wouldn't write it off without trying it.

One tube I've been curious about trying in the amp is the EL84. I generally like this tube very much and have several pp amps that use it. I may give them a try as I have adapters that would work. I know this means much less power output. Still

Contact me if you want a pair of 807's to try for a little while. Happy to lend you a pair.

[FloridaBoy]

X3, if your amp is triode wired EL84's may be 2 watts or so.

[Rosco65]

Unrelated to the current discussion, but I just noticed a circa 2013 KT150 FIrebottle amp (6DJ8 type input) for sale for $1,800. I didn't realize our collector item amplifiers were appreciating in value so quickly.

[pstrisik]

Originally Posted by Rosco65

Unrelated to the current discussion, but I just noticed a circa 2013 KT150 FIrebottle amp (6DJ8 type input) for sale for $1,800. I didn't realize our collector item amplifiers were appreciating in value so quickly.

They may or may not be. The answer will be in the sales price, not the asking price. And, FWIW, my KT150 was not much less than that with the extra $ for special color request.

Is it on ebay?

edit: post searching, I see one on US Audio Mart for $1900 from 2014 in the standard black with walnut face. California seller. Same amp listed on AudioAsylum. May be a different one than you found.

[x3workshop]

Originally Posted by FloridaBoy

X3, if your amp is triode wired EL84's may be 2 watts or so.

Yeah, I figured it was 2-4 awesome watts.

[Rosco65]

Originally Posted by pstrisik

They may or may not be. The answer will be in the sales price, not the asking price. And, FWIW, my KT150 was not much less than that with the extra $ for special color request.

Is it on ebay?

edit: post searching, I see one on US Audio Mart for $1900 from 2014 in the standard black with walnut face. California seller. Same amp listed on AudioAsylum. May be a different one than you found.

Audio Asylum Trader. Price is $1,750. It appears to be a stock model. My KT88HO is identical other than color and KT88's instead of KT150's, but that should only add about $70 to the price. I paid $1,250 for mine in early 2016. These are 15W models, not 20W models that sell for $1,800 or so.