[sflai]

I am looking for a SET amp (especially interest in 45 or 2A3). Can anyone share your experience with or comment on Promi 45 or 2A3 SET Mono? How it compare with other option such as yamamoto A08s?

[Christopher Witmer]

I have no experience with any Promitheus product but I know there are some very happy users of 45/2A3 SE amps with Feastrex drivers. I would strongly recommend that you consider enquiring about the possibility of upgrading from EI core (M6) to C core (M2) iron and EVEN MORE IMPORTANTLY see if you can have an even higher impedance tap added to the OPT, in addition to the 16-ohm tap. I suggest 22 ohms. Then you can try driving them from both 16-ohm and 22-ohm to see which you prefer. I don't know what the cost difference between EI and C core is but if cost is a limiting factor for you, start replacing EI with C cores from the OPTs and work back from there toward the choke and power transformer as your budget permits.

I also encourage you to enquire concerning possibilities for using nanocrystalline (Finemet) core material . . . this material is more expensive but I believe you may be able to use smaller cores, thus partially offsetting the additional cost. People I have spoken to who have tried Finemet now say they don't want to use anything else, at least in their OPTs. (Finemet power transformers can get pretty pricey and perhaps there is less of a return on one's investment than in the OPTs.)

There is information on Finemet core material on pages 6 and 7 of the following brochure:
http://www.mkmagnetics.com/dataSheets/pdf/brochure051104.pdf

-- Chris

[PromitheusAudio]

Sflai
person to speak to is Stanton, Feastrex dealer in Hong Kong. He has used our amp with the Feastrex drivers. He used to use Sun audio as i recall. Do note he is our dealer in the HK. You can search for One C Audio, from the feastrex page to get his email.

Chris
you are exceptionally right on the finemet/ nanocrystalline material, i send you a thank you email letting you know how well it works for personal rig. Sounds is really great, so was the price. Chris introduce me to this material and i have to agree with him.
As i recall, i recommended Stanton to put in the 16ohms tap should have done 22 ohms then for him

When the ecomony picks up and i have spare catch would have to consider the Feastrex speakers, playing around with an AER for now first

[Christopher Witmer]

  I had forgotten completely that Stanton Tin, Feastrex's representative for Chinese-language markets, is a happy user of Promitheus amplifiers.

I'm glad the Finemet/nanocrystalline cores turned out to be "keepers" . . . Promitheus may eventually be getting some orders from me too . . .

We're all just one big happy audiophile family!

-- Chris

[sflai]

"We're all just one big happy audiophile family!" - Absolutely agree with you, Chris.  In fact, I know Stanton Tin I am from HKG, too. He also recommends me to try the nanocrystalline version of Promi 45 SET. Nick, is the nanocrystalline version officially released?

[fr338]

I am the happy user Chris mentioned. 

I have some updates on my Promi 45 amp. After using the amp for three months, I decided to do some tube changing to see how it performs. I do not have idea of the Siemens D3a input tube, so I change the  rectifier tube. I have done a lot of these exercise when I still own the Sun Audio 2A3 amp, so I have a stock of tubes that can just do a plug and play. I bypassed to use the most popular 5U4g and do a plugging with 5AS4. I love this tube so much for its value for money. Not surprising, it gives a quantum jump in the performance. When I first received the Promitheus 45 amp, I felt it sounds a bit slow, though a lot more neutral and greater headroom than Sun Audio amp. 5AS4 gave life to the Sun Audio amp, and it is on it that I heard the lightning speed Feastrex D5nf for the first time. Now on Promi 45 amp the magic plays again. I recalled the thundering feeling I once got before, and at a even more massive extent due to the excellent headroom of Promi 45 amp. The bass has substantial extension too. For this I mean a real bass note information, and not a out of control booming.  For a 5 inches speaker it may not stretch beyond the physics, but the bass such produced is  so realistic.

After two days of adaptation to the excitement, I decided to plug in the WE422a. I do not have the practice of using exotic rectifier tubes, essentially because I believe rectifiers are consuming items as they are at the front line guarding the amp. But I am distracted to do so as the headroom of the promi 45 amp drives me to believe it is a platform with unexplored potential. So it went the plugging in of WE422a. After turned on again for 5 minutes, I can only sit still on the sofa. Being professionally trained in electronics( ok, I am a solid state guy basically), I have absolutely no idea why a rectifier tube have such profound change to the overall performance. If there is something called full range speaker driver, then there must have full range rectifier too. On WE422A I have heard the bass extension I never heard from Feastrex before. I am using the triple reflex box. I love it much more than the later floorstanding box for the bigger box has traded speed to certain extend. And on this triple reflex box, I get the bass performance that is better than a driver that has a Fs of 40Hz in a mass loaded TQWT box, and comparatively D5nf has a measured Fs of 80Hz or higher( my own measurement way back one and a half year ago). The background is much darker too. The liveliness such presented is quite shocking to me. The HF performance is about the same as 5AS4, or maybe I have overwhelmed already by the surprising results. Now I am tempted to get  274a/b .    But putting hands on my wallet  my rationality tell me they are just diodes.

[PromitheusAudio]

Good to hear about the rectifer change. Our amps and preamps responds really well to rectifer or any tube rolling effect. So i am not suprise but now on the hunt for this tubes

THe d3a can be swap for e180F. Different sound. Its a more dynamic sound. Less gain though

[supergroverd]

I am the happy user Chris mentioned. 

I have some updates on my Promi 45 amp. After using the amp for three months, I decided to do some tube changing to see how it performs. I do not have idea of the Siemens D3a input tube, so I change the  rectifier tube. I have done a lot of these exercise when I still own the Sun Audio 2A3 amp, so I have a stock of tubes that can just do a plug and play. I bypassed to use the most popular 5U4g and do a plugging with 5AS4. I love this tube so much for its value for money. Not surprising, it gives a quantum jump in the performance. When I first received the Promitheus 45 amp, I felt it sounds a bit slow, though a lot more neutral and greater headroom than Sun Audio amp. 5AS4 gave life to the Sun Audio amp, and it is on it that I heard the lightning speed Feastrex D5nf for the first time. Now on Promi 45 amp the magic plays again. I recalled the thundering feeling I once got before, and at a even more massive extent due to the excellent headroom of Promi 45 amp. The bass has substantial extension too. For this I mean a real bass note information, and not a out of control booming.  For a 5 inches speaker it may not stretch beyond the physics, but the bass such produced is  so realistic.

After two days of adaptation to the excitement, I decided to plug in the WE422a. I do not have the practice of using exotic rectifier tubes, essentially because I believe rectifiers are consuming items as they are at the front line guarding the amp. But I am distracted to do so as the headroom of the promi 45 amp drives me to believe it is a platform with unexplored potential. So it went the plugging in of WE422a. After turned on again for 5 minutes, I can only sit still on the sofa. Being professionally trained in electronics( ok, I am a solid state guy basically), I have absolutely no idea why a rectifier tube have such profound change to the overall performance. If there is something called full range speaker driver, then there must have full range rectifier too. On WE422A I have heard the bass extension I never heard from Feastrex before. I am using the triple reflex box. I love it much more than the later floorstanding box for the bigger box has traded speed to certain extend. And on this triple reflex box, I get the bass performance that is better than a driver that has a Fs of 40Hz in a mass loaded TQWT box, and comparatively D5nf has a measured Fs of 80Hz or higher( my own measurement way back one and a half year ago). The background is much darker too. The liveliness such presented is quite shocking to me. The HF performance is about the same as 5AS4, or maybe I have overwhelmed already by the surprising results. Now I am tempted to get  274a/b .    But putting hands on my wallet  my rationality tell me they are just diodes.

Hi Fr338,

I am an Promitheus 45/2a3 owner (and 300B by the way) and pretty happy with my set-up. I use Tonian TL-D1's which are just great speakers (with an incredible pricetag). I am now looking to get some new tubes and hope you can help me out a bit. At the moment I use the standard tubes. Now I am wondering If you can give me some advise The 422a's look very nice, but 400+ USD....(worth it..or maybe EML's)! And for driver tubes, and power tubes ...? Any suggestions maybe?


Cheers,
Supergroverd

[tanchiro58]

Good to hear about the rectifer change. Our amps and preamps responds really well to rectifer or any tube rolling effect. So i am not suprise but now on the hunt for this tubes

THe d3a can be swap for e180F. Different sound. Its a more dynamic sound. Less gain though

Nick,

I would like to ask you about the current price of 45/2A3 monoblock amp and how can I change from 2A3 to 45 (I know I have to specify my order) if I need to do it once I get a 2A3 amp? Let me know.

Thanks,
Tan

[PromitheusAudio]

Tan
just send you a PM

thanks