My integrated Decware dual-mono Mini Torii has the OA3 voltage regulator tubes (one per channel) designed so it would reduce noise by filtering it at the cathode jump of the signal through those regulator tubes (same principle). But, it is wired for 6V6's as a Pentode, and maybe for that reason it does not compete with my Inspire KT-88 Triode amp in SQ.

One thing I strongly believe in, as a somewhat experienced observer and user, is that the simple SET amp circuit is more direct and natural and less prone to unpleasant distortions relative to more complex designs. The only real trade-off seems to be heat dissipation and power inefficiency, secondary considerations when one primarily seeks SQ. Lower power levels are negotiable through the right speaker sensitivity choice and the listening room geometry and sizing. I'm sure someone more enlightened could correct me, for example, explaining why the so-called improved dynamic response in a Pentode arrangement beats the old man's Triode amp :), or how could a Pentode sound as good as a Triode, as in the proposed Universal design discussed earlier, assuming the same quality designer/considerations are applied in each case ...

From DH, “radical output transformers”!

Attachment 54668

Well, that would definitely help. Sound quality of some of the best Japanese amps of this kind can be traced to their meticulously designed and assembled silver wiring transformers, a big chunk of their high price. But, what would happen if the same transformers were to be applied in a very simple (purist), Triode SET design? I'm fascinated with this topic, which I know too little about :( The trick is, once you have a decent Pre/Amp setup, signal source fine-tuning yields the most improvements, as now every little tweak is tangibly magnified by amplification. One needs to balance out these two aspects to achieve a very nicely sounding rig within budget constraints.

Thanks for the info. I was thinking that some of the stepped attenuators (from Poland or eastern Europe companies?) came with remotes and are less expensive then I had thought.

Methinks that was tongue in cheek on Dennis' part. Tubes are what he was referring to. :D

Actually, the transformers are a new design... The improvements never stop...:thumbsup:

Hey YB-2, If you have a name for the attenuator manufacturers you mentioned that would be great, I would love to find a nice remote set-up for Inspire preamps. Thanks!!

As long as those improvements don't push the new offerings outside the current market niche, I'm all for it! :yes:

Elna & Khozmo are two that come to mind. Bentaudio offers add-on motorized controls for the attenuators used in Goldpoint passive preamps.

Here is a motorized potentiometer that competes with Alps: https://www.hificollective.co.uk/pot...ntiometer.html

Thanks for the info YB-2, That TKD motorized pot looks sweeeeet!!, I'll use the TKD's sizing specs and do some measuring in a chassis to see whats what, the motor housing on the TKD is not offset like the Alps is, so it will be a little closer to the left hand tube socket, but it should still fit. I will keep you posted. That remote kit looks nice too, and runs off 6.3v, so no seperate power supply needed! I had looked at a BentAudio/Danish Audio ConnecT combo with a Danish Audio ConnecT selector switch awhile back, but I think I had to buy in quantity to get a good price, so I never pulled the trigger.
thanks again for the help, it is much appreciated...Tony

Tony - you're welcome. Please keep me (us) posted. I'm preamp shopping and will probably do a piece of Schiit ;) for the short-term. Am hoping Dennis will do me a pair of 6922s feeding a pair of 6SN7s with tube rectification. And a remote volume control, of course. :thumbsup:

My lp-2 upgraded to lp-3a has 6h1ns feeding a single 6cg7. I rolled some 6922s and ended up back with the Russian Rockets. Of course Dennis originally designed the pre around those RRs. The point I really want to make is that I love that Preamp. It is a great piece. I have an Lp-27a special edition which does have some clarity and refinement the other does not but those little tubes sure do sound nice. I have no plans to get rid of either one.

My new-to-me Schiit Valhalla 2 uses a pair of 6N1Ps (6922, etc.) feeding a pair of 6N6P tubes. Should be interesting to listen to as it breaks-in (arrives next Wed).

Would you kindly explain what are the differences between your "Special Edition" and our normal LP-27a? Thanks!

Sorry, I wish I new more. My wife got the 27 for me for Christmas a couple years ago. I gave her Dennis # and had been in discussion earlier with DH and said that I wanted one with " the works". A stepped attenuator and some upgraded parts as I remember but I do not recall the particulars if I ever new them. It is signed as a LP-27a 'Special Edition'. I can post a picture of the innards if you would like to compare.

The LP-27a is a nice little preamp. I have a standard build one in the copper color. I just wish my black PSE amp matched it.

I have an early LP-27a (and early PSE - I actually had to send it back immediately to have the IIPS mod installed). I requested a DACT attenuator, but Dennis did not suggest any other changes. Mine have Mundorf coupling caps, but he may have changed to Auden True Copper afterward, and IIRC, he may have added an additional choke stage to the PS at a later point.

I’m not sure if any Inspire products are truly standard. There appear to be default circuit and parts choices, but running changes appear to be the norm.

Thanks for the info. Mine also has a DACT stepped attenuator. No big deal, I was just curious.

This may have been asked before, but do any of you LP-27a owners have a favorite tube combination you prefer to use in it.

I go for the balloon-type 56's (any brand, these just sound more transparent than the 27's in my system), with a Pope 80. I've returned to the original 6BX7 for the input from a Psvane 6SN7. YMMV

I too go for 56s but have not found a pair of balloons which were listenable due to noise. Manuf. not important. I run a tall bottle Westinghouse 6sn7 with the copper posts and any 80 will due.

Does anyone have a list of the different types of output tubes that can be used with the Inspire KT150 Hot Rod amp?


I recall a hand-written list Dennis took a photo of and someone posted it here or another forum. Cannot find it.
There are some old 2013 posts that talk bout different tubes but I thought Dennis handwritten list was more extensive.
Reached out to Dennis too, to see what he can provide, and maybe it's in the gallery here or something, cannot find it.

Hey decooney, if yours is one of the new Triode-strapped KT-150 Hot Rods then asking Dennis for output numbers would be best.
straitwire

Think I might have just found it. Saved a copy. I forgot, some times he adds this as a photo to the sale ads.



https://lh3.googleusercontent.com/A8...A=w968-h726-no

I believe this list is for Pentode configuration, looking at the bias resistor value and the power levels.

Thanks so much for the list. In my PSE, I’ve always just stuck to either KT88’s or 6550’s.

Okay, maybe you can help answer a few questions. This is the tube list Dennis offers with the Inspire Fire Bottle KT150 Triode Hot Rod sale ad, one of the last pages on the auction. This is where I re-found the photo. I have a note out to Dennis, he may see it next week.

My amp has "Triode" listed on the face, and runs KT150s, and many of these same tubes,

...so does that make it a pentode or triode configuration? And, will some these tubes not work on my KT150 Triode Hot Rod amp?

Hey decooney, your amp is configured in the latest Triode strapped circuit, I went to eBay and pulled down the old/sold listing for your amp and there isn't a picture of a tube list for that amp, but there may be a list by now. With what I know about the circuit I can say that you can run KT-150-120-90-88, and 6550's,...all the big tubes, the KT-77-66, and 6L6-6CA7/E34L and the 6V6 I don't know for sure but probably, the 6V6 might red plate though. Dennis will get back to you as soon as possible, thanks for your patience...straitwire

UPDATE:
Okay, may have a answer. Dennis got back to me and clarified why I'm having trouble finding the correct tube list for my recent amp purchase of the Inspire KT150 Hot Rod amp":

"Sorry for the confusion …. I have not done a tube chart for the Triode Hot-Rod version. I will gather up a bunch of tubes next week and make a chart for the “Hot-Rod” version. The chart you may have seen was for the triode SET “Fire-Bottle”. This is the lower powered version of your amp. Talk to you next week."

I let Dennis know I would post it here once he creates it for others who may want it too. I thought my amp was 10wpc. Then I see HO again on the front.
So now I'm even more curious, what is the power of my "HO" Hot Rod amp then with two KT150s in it?

https://lh3.googleusercontent.com/AJ...=w1218-h913-no

This forum seems kind of "dormant", so I'll step in with some observations on my current system (rig is on my signature):

1. Even though I have yet to get me a larger Subwoofer (Rythmic LS-12), the sound in my system has tangibly gone to a higher level through modest source modifications (Schiit EITR and JPlay SW). Now I'm not even sure I need that sucker :)

2. The above additions have made me reconsider the KT-77´s (definitely my favorites up until now) for the KT-88's (all Genalex, of course), just because the neatness of JPlay through a virtual network using Linn Kazoo and MinimServer through JPlay makes the sound so much detailed and transparent sometimes I miss some more body (not that it is required, but it is just my preference).

3. The combination of the KT-88's with the new sourcing components (other things being equal) is fantastic! Similarly, I can use the KT-77's with JPlay Mini instead of the cited virtual network and get roughly the same results. At this point I'm not sure what I like best, I guess it depends on the recording quality of each music selection.

I've always been a nut for transparency and detail, along with musicality and body of sound. I'm getting there so fast I cannot believe it! For the first time in years I feel I'm sitting on the platform which will witness my last audio days ... Dennis Had Inspire Pre's and Amp's (in Triode) rule! I'd like to urge you to chase your sound objectives through converging gradual mods and improvements until you really feel you are close enough to that envisioned Holy Grail and can finally relax and harvest the results of your efforts. It is worth it!

Well............. if hasn't been said in 4400 and some odd posts............ ;)
Is this the longest thread on AAf?

Have you tried any other rectfiers with an adapter in place of the 80 tube?

I've only used 80's in the LP-27a. I've been assuming this rectifier is the one the Pre was designed for. Since a Pre is quite delicate and easy to derail from the intended design aimed at avoiding adding noise, color and other nasties to the signal before amplification, and since mine is quite transparent (in my view), I've never even thought about experimenting with other rectifiers (as opposed to the Amp's case).

... What other alternatives are there with/without adapters?

Oh sure, this has been a very rich and resilient thread ... I just meant it seemed quiet recently :D

I have some nice 5Y3's I was thinking of trying in the LP27a with adapter. It seems most of the 5 volt rectifiers can be used with the amps.

On the Amp? Surely! The 5Y3 GT, for example, is virtually electrically identical to the older four-pin type 80 tube, but with an octal base. In the Amp I pair different rectifiers with the kind of output tubes in each case.

My point is the Preamp may not feel happy with an adapter as this in itself is another source of signal path intrusion. Of course worth trying to compare, but in my book it is not necessary. The 80 is remarkably inconspicuous. The beauty of this Pre is its contribution to body and gain with barely a tradeoff. Part of this achievement stems from the 80's traits. By all means give it a try and please report back.

You are so right. I think I will just stay with the 80 on the LP-27a. I've got plenty different ones to roll.

The LP27a is designed for an 80 or 5Y3. You will likely have an early 4th of July if you try anything else. The Inspire amps are where you can experiment with rectifiers.

Not sure about that. If you go back a couple years here you will find that those of us with octal rectifier sockets in our linestages have tried every rectifier we have tried in our amps to varying degrees of satisfaction. That being said I have not with my lp-27a. If I was still rolling like a mad man as before I would confirm with DH and have at it.

I would confirm with DH :thumbsup: