The 17 watt version is the high output (HO) amp that has one output tube per channel, widely space apart as opposed to the amp which has everything bunched pretty tightly together. If you check past pics and the auction site for completed auctions you can see both types. I had the 17 watt version before getting the PSE, in fact had both together for a bit to compare. I had wrongly assumed the simpler circuit SET HO would be better but the PSE was quite a step up, as Dennis had said it would be.

The "17 watt" amp is Dennis' tweaked up Inspire SE KT88 HO amp which normally produces 12 watts per channel, the one he has sold many of this past year. Larger output transformers, a few circuit modifications, higher voltages. It pushes the KT88 tubes to close to their maximum output in single-ended mode. I don't think he has made many of these.

Well said! And they are very nice amps also!

"new mono-blocks", do tell!

I've really missed good old Denn. The hospital is letting me out on day release now, so I penned this ditty;

Dennis Had dennis Had riding through the glen
Dennis Had dennis Had and his 40 AA men,
He takes from the wealthy, gives little to the poor, does deh dehhnis Had,

He inspires Chinese water torture treatment,
Rad's sanity is taking an elopement
He cared nothing for the Olympics in Rio,
But his stuff sounds nicer than a FiiO
We must never lose track of Dehhhhhhnis Had.

Is Dennis going to be selling his own line of monoblocks in addition to those being sold under the Moon Audio Dragon Inspire label? Those are marketed as only 6v6 amps.

The Moon Audio description includes the following: "Each amplifier is hand-built with point to point wiring by Dennis Had himself. Each amplifier is hand signed by him on the botom plate. Dennis considers this his form of art. Each amp is like a newly sculpted masterpiece.

He personally listens to each amplifier, both in the shop listening room and his home listening room, before it is shipped out. "

Thanks! I needed a confirmation. The one you described is my amp. I can't honestly believe it can be improved so tangibly, as you have attested, because mine sounds so great I thought it would be hard to beat. That must be something worth listening to in my future. More power and better sound quality at the same time ... Dennis seems to be at his best working at home without the business pressures he had all those years. I wonder how would his 45 SET compare in sound quality ... I guess less dynamics and better mid-range tone?

The dynamics and tone of an amp are not strictly related to the output power, but rather the characteristics of the amp and the amp/speaker relationship. The 45 tube can be a very dynamic tube given the appropriate speaker. I've owned a 45 amp, and its had both great dynamics and perhaps the best midrange tone of any amp I've heard. It does, however, constrain the speakers you can reasonably use in a typical (>150 sq ft) listening room.

The 45 tube is generally a less romantic and more revealing tube than a 300B or 2A3. It also requires a 5K output transformer, which helps in controlling the speaker and in my experience allows for better bass, given a speaker of >97dB sensitivity.

I can't speak to Dennis' 45 amps. I know in the realm of SE beam power amps Dennis' amps seem to occupy a unique place (maybe along with Shindo) and have a modern sound that still retains great tone. However, the DH DET amps are the deep end of the pool, and there are some very talented designers (e.g., Gary Dews, Gary Dahl, Joseph Esmilla, Hiro Kondo, Gordon Rankin, Herb Reichert, Jeff Korneff, Don Garber) who have refined their designs for decades. I have no experience with an Inspire 45 amp, know that the bar is pretty high when competing with the likes of Fi, Korneff, Border Patrol and Wavelength. However, when cost is taken into consideration it may be very close.

One appeal to the Firebottle series of amps is that with pentode connection the output power ranges from 5-20 WPC. That kind of power allows for use with most speakers with a sensitivity of 90 db or greater. That means we no longer have to rule out some great speakers with low 90's sensitivity (like Devore Gibbons) to use a SE amp. In contrast, SET amps require us to go with a 300B or 845 to get 5 watts or more, or resort to the more difficult path of PSE. Both of these options are more expensive than using a 45 or 2A3 amp.

Thanks for the thorough explanation! I believe the Triode-strapped Beam Tetrode configuration is an optimal compromise between the DH SET and Pentode-strapped SE configurations. This approach gets some of the magic of a DH SET and some of the dynamics of the Pentode-strapped SE. Tradeoffs are unavoidable, of course, but the less expensive output tubes and amp design of a Triode-strapped Beam Tetrode makes it quite appealing.

Enter the Parallel SE design and all of a sudden you get more power and drive, but I'm still not sure (theoretically) why would it be better-sounding than its single output tube per channel version. I know Dennis explained this somewhere but whatever it accomplished it could also be applied to the single tube per channel design because the only difference is the extra tube per channel in parallel and the different output transformer design.

If the aforementioned PSE design requires such special transformers to nail the trick without affecting SQ (apparently in fact, improving it), then I would assume equivalent special transformers may work for the single tube per channel option and be even better sounding (simpler = better) if one is not interested in the extra power (like me).

The choice/design of the output transformers make the difference, and I think Dennis should offer even more beefed-up transformer options for the Triode-strapped Beam Tetrode (single ouput tube per channel).

The other avenue I was considering for the future is the 45 SET, which, as you rightly pointed out, is the best SQ compromise among DH Triode output tube SE's if one can live with the restricted power and speaker limitations. Is good to learn 45's can be as dynamic as other options.

I'm not sure I 100% agree with your position. The special output transformers Dennis implies are necessary for PSE may also be in part responsible for the improved performance of the PSE specifically because they are special, just as the 20w transformers in the higher output KT88 amp may be responsible for its reported improved performance over the standard version. The quality of output transformers has a lot to do with sound quality (in PP and SE), and in a typical SE amp comprise the major cost (look up the price of Lundahl, Magnequest, Tango, Tamura, Electraprint, or Hashimoto outputs).


The PSE also allows for a lower impedance, theoretically allowing for greater control of bass drivers. Dennis also implies that the amp sounds best operating at less than maximum power, preferring either the 5U4/KT88 at 15 watts or - preferably - 5U4/6V6 at 10 watts. Running the amp this easy may allow it to run in a more linear region. To put this in perspective, getting more than 10 watts from a single tube in SE requires cranking a KT88 pretty hard. This may sound great in a different way but perhaps not the best it can. To get 17 watts from a single KT88 requires running it at maximum output. For most of us with speakers with sensitivity less than 95dB, a linear 10 watt 6V6 PSE may be much better than a 5 watt 6V6 SE (equal to a 3dB difference) depending on room and musical tastes.

Now, as to true SET's, I didn't say that a 45 is the best compromise among SET's. In fact, the 45 is probably the lowest power common SET and has a reputation of "highlighting" the music, especially in the upper registers. It can be dynamic, but needs to be appropriately matched with the right speakers, usually horns of >100dB. In contrast, the 300B has a more typical rounded triode sound (in typical applications), but outputs an 8wpc that is usable by many speakers of 90dB sensitivity or more. The most common compromise between these two is the 2A3, with a 3.5 watt output. Another compromise, albeit less common (with tubes out of production) is a 421a/5998 amp (though this tube is indirectly heated, which can make it quieter) which gives about 4.5 wpc and leans more to the 45 side than 300B side. This doesn't count European tubes such as the AD1 which are beyond my knowledge and experience. In any case, to get more than 8-10 watts requires us to either parallel the triodes or go to transmitting tubes (845, 211) that run at much higher voltage and have much more complicated power supplies and circuits.

I don't think that a triode-connected pentode is better than a true DHT, but it can sound great in the right circumstances (the Decware SE84 triode connected EL84 punches way above its weight class). I also don't think that getting into the pentode/triode-connected pentode/DHT dogmatic argument is all that productive. There are legendary amps - both PP and SE - that use all tube configurations to deliver world-class sound. Each may have a different character but the end result is great musical reproduction. Shindo Audio offers a number of configurations: PP, PSE, SE using both triode and pentode tubes, though not triode-connected pentode to my knowledge. Each of these amplifiers is magical in its own way, and none can be said to be absolutely better than the other, only different and inevitably appealing to different musical tastes.

TL;dr - the quality of output transformers is very important, and may be partly responsible for the superiority of the PSE over the Firebottle SE. Additionally, the extra power of the PSE is difficult to achieve using a single tube unless you whip it hard, possibly into higher levels of distortion. PSE lets you get a good 15-20 wpc (nominally 12 dB) which means you can use almost any reasonably sensitive speaker, and there are a lot of great sounding ones out there.

As far as a 45 SET, I think it is one of the best tube ever (along with the VT52 and 50) but requires your to accept certain compromises: your speakers with need to be extremely efficient to satisfactorily fill larger spaces, very efficient (>93dB) when used in the near field or in smaller spaces, and in both cases you may want or need active bass support depending on your expectations.

If you do want to go the 45 route (or anything < 3wpc) then your speaker game needs to be appropriate. I've found that speakers with highish impedance and minimal crossovers work well. I have personal experience with Cabasse (older DIY models of 94 dB sensitivity) and various Omega speakers. The latter really work well and begin at $600 with the most expensive models topping out at $4k. Where it would really shine is with ultra high efficiency horns. I'm partial to Altec, but I am biased.