Low powered SS amps for high efficiency speakers

[atharva]

Interesting experiences. I've read/heard many conflicting comments (even from experts and designers) on 2A3/300B, OPTs, SS vs tubes and all things audio. And I'm sure all those views are true. That was their experience. Several years ago I heard a pair of Maggies paired with a Jolida CD and integrated amp at a friend's place. I was so blown away by it that I picked up that exact setup (including all cables) and got it home. But it didn't sound the same! Back at my friend's place the magic was still there. I wondered if I had developed a confirmation bias! But with room acoustics playing a major role it is little wonder how our experiences can be different. The best way (if possible) is to experience for yourself in your listening space. This is just an attempt to try an SS amp and it is possible I might prefer the tubes in the end. Unfortunately we don't have 30 day home evaluations.

Sorry, enough rambling, back to low power SS options

 

[Deleted member 15865]

Interesting experiences. I've read/heard many conflicting comments (even from experts and designers) on 2A3/300B, OPTs, SS vs tubes and all things audio. And I'm sure all those views are true. That was their experience. Several years ago I heard a pair of Maggies paired with a Jolida CD and integrated amp at a friend's place. I was so blown away by it that I picked up that exact setup (including all cables) and got it home. But it didn't sound the same! Back at my friend's place the magic was still there. I wondered if I had developed a confirmation bias! But with room acoustics playing a major role it is little wonder how our experiences can be different. The best way (if possible) is to experience for yourself in your listening space. This is just an attempt to try an SS amp and it is possible I might prefer the tubes in the end. Unfortunately we don't have 30 day home evaluations.

Sorry, enough rambling, back to low power SS options

Did you check with the Rethm designer? What’s their recommendation? There’s value in Prem’s point that the amp needs to play to the speaker’s strength (accentuating strengths rather than compensating weaknesses - that could make them lose their distinction). And who better than the speaker designer to guide on this - he’d have tried matching more amps than anyone else.

Then again, you have been using the speakers with the amp that’s most suggested. And as you wrote, you want to ‘experiment’ with other kinds. So you’d be prepared to be surprised - either ways. Do post the findings - it will only add to the collective know how of the forum.

 

[prem]

Atharva, I have owned lots of speakers. IME, Rethm was probably the most sensitive to speaker placement as compared to others that I have owned.

 

[atharva]

@prem I learnt that the hard way. It was interesting how this happened. I had started with a placement that "fit" without disturbing the living room FM @dheerajin had invited me over to listen to his setup and we had a great session. I decided to experiment and found the sound improve with some changes. Now, I'm waiting to redo the interiors to suit the listening and I've brought on the wrath of you know who!

Sachin, I hate to quote a designer but I think the suggestion was to use any good SET tube amp. In fact, Rethm's own Gaanam amp was neither a 2A3 or 300B. Jacob certainly likes more power.

 

[prem]

Atharva, look up LTA ZOTL 10 integrated. Should work. You will get as close to SS as possible but with the magic of tubes. I have owned the Berning 6b4g class A amp. It’s a good match.

 

[atharva]

I approached First Note Labs and they said they can build me a 15W or 30W Class A SE amp. First, I'm glad that we have more Indian brands coming up. Have been emailing them and they've been super responsive and very professional.

Would love if some owners chip in with feedback especially if they're using high sensitivity speakers.

 

[Arajsriv93]

I am planning to get a 2.2 stereo amp build from scratch and considering using lm3886 ics and a good preamp board. Lets see how how it goes.

 

[drlowmu]

Keeping away from Tubes for now just to try an SS. I've been bugging Jacob to come up with a Gaanam alternative.

I'd love to try an ACA. Correct me if I'm wrong but I assume the J2/F3 etc would be much better albeit at a higher price.

Is the ACA the Nelson Pass AMP CAMP amps, a DIY kit? If so, we run DC 2A3s, and two of my friends bought and built ACA amps, and they both individually sent their Amp Camp Amps to me, to sell for them on eBay.

You would be better off learning how to build GOOD DC amps with 2A3s. A good 2A3 amp in our experience, is only of one design : a two stage DC amp. Even when Nelson talks on the phone to my mentor, Nelson says privately ........" triode tubes are better ". He will not say that in public places I bet.

Jeff

iMO, Try PSE 6AS7G and you will be blown !!! Makes about 5 watts per channel. Bass is most amazing you would have ever heard from an SET. Mine are monoblocks and Pure Class A.

Is PSE " parallel single ended ". If so, you need to know that ANY time you parallel tubes, Finals, it is a compromise. A good single 2A3 that the original poster uses, is superior. If you have to run PSE, you simply have a speaker efficiency problem. Get the speaker correct first..... and good things in hi fi happens .......101 dB does it.

Jeff

I will try and answer it as best as I can. I have heard the Rethms with a variety of tube amps from a 45 to a 2a3 to a 300 to a 845 to a 6c33. A 300 tube is not as agile or quick as a 2a3 which in turn loses out to a 45 tube when it comes to speed and agility. Rethm likes amps which are very agile. Unfortunately a 1.5 watt 45 tube amp for some reason doesn’t work too well with Rethm. The 2a3 which is 3.5 watter works perfect. The 50 tube which is the grandfather of the 45 tube will probably work even better with a Rethm. Similarly there will be speakers which prefer a 300 over a 2a3. The synergy between amp and speaker is more critical. On even higher sensitivity super expensive speakers like Pnoe, the 45 or 46 tube amp work the best. And that’s just a 1.5 watter. A 45 tube amp is different sounding from a 2a3 tube amp which is very different sounding from a 300 tube amp. Each SET tube sounds very very different from each other unlike pentodes where there is a little more similarity.

I'd like to express my opinions on tubes.

In my building experience, the Type 45 is a bust.

An ST 45 tube can never in a million years ever play the lower registers of a grand piano effectively. It has a non linear playback in that range. Advanced audiophiles may know this. Read Joe Esmilla's SIMPLE 46 amp blog of 2017, when he experienced his very first 46 at home for 90 days.

JE Labs Simple 46

jelabs.blogspot.com

or, Thomas Meyer in Germany. http://vinylsavor.blogspot.com/2016/12/the-46-back-in-black.html

The 46 is better. A single plate 2A3 can be very good, such as a JJ 2A3-40, or EML or the NLA VAIC mesh plate.

A 45 is non linear, due to its cheap too-thin internal wiring, from the plate's assembly to the tube socket pins. A 45's best use is in vintage radios. It was massed-produced in the day, to be as cheap as possible.

More modern tubes are made better. Type 50s are similar to the 45s, nice highs etc., non-linear bass response. No thanks, been there / built that / done that.

I use 101 dB horns for testing, with ALTEC drivers, 515B and 802D. A more modern-built 2 dollar 6AQ5 or a 10 dollar NOS 6005, will murder many of these tubes people discuss, when evaluated in a single amp, full-range playback - on a highly-efficient speaker. I love testing tube amps on grand piano playback !!

300B amps, in my opinion, are a mistake. They require DC on their filaments, and this bucks-out the ultimate in fidelity that you can obtain from a AC operated 2.5 volt 2A3 tube. The real mistake of a 300B amp, is that the owner did not start the audio journey with a 101 db or higher speaker, so they are forced to use amps over two Watts, which are clunky - sounding. The 300B amps are by their nature, slightly inferior in terms of the highest possible audio performance.

( Yes, I know, many rooms are small in a densely populated country like INDIA ).

All of this I write and share with is " only in my experience, in my opinion. " My background : I have been listening - to 15 inch ALTEC drivers for 76.8 years now. Have fun in the audio hobby. I do.

Very respectfully submitted to you.

Jeff

 

[Yogesh]

I approached First Note Labs and they said they can build me a 15W or 30W Class A SE amp. First, I'm glad that we have more Indian brands coming up. Have been emailing them and they've been super responsive and very professional.

Would love if some owners chip in with feedback especially if they're using high sensitivity speakers.

What did you get in the end?

First Note Labs

We don't seem to talk about First Note Labs nowadays! :Thinking:

 

[Hari Iyer]

What you need is a new pair of output transformers. Be prepared to spend a minimum of 40k on the OPTs. The difference will be profound. I am speaking from personal experience. Most 2A3 designs are simple and similar, the key differentiators are the OPTs(resistors and capacitors matter too) and the layout/grounding scheme. Sometimes superior OPTs and sensitive speakers reveal issues related to hum.

For getting good speed the OPT can't help much imo. The problem lies with the powersupply. Most tube amp power supplies use C-L-C filtering with around 5H to 10H of inductance for the L with a DCR of 100+ ohns This makes the amplifier sluggish and slow to respond. Also the capacitors are around 200 uF + which also is a culprit for speed.

To achieve good speed try L-C-L-C filter topology for power supply with L around 400 mH and 6 ohms DCR and C not more than 30 uF to 50 uF. This will help the amplifier in better dynamic response and speed.

 

[300b]

If interested in Lyrita Audio set GM70, you may come home, listen,
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[lowpoweraudio]

Hello friends,

Hope you and your loved ones are safe.

Thanks to the lockdown the idle mind has started to imagine what-ifs . I'm using 2A3 tubes right now and am considering experimenting SS amps with my Maargas. A 300B is still on the cards but may be later.

First Watt amps were the only ones I could find. More than 15 Watts would be wasted watts and heat. The SITs are unobtainable so the F1, F3, F7 look like the best candidates. The J2 is also current production although more power. The J2 is $4K, F7 is $3K and SIT3 is $4K.

If I were to take the DIY route looks like there are 3 choices. J2 Clone, F3 and SissySIT. There seems to be not much activity on the F3 any more. The J2 clone will be expensive because of the Semisouths (still cheaper than the original J2). I don't think there is a DIY F7. BTW, I don't mind paying more for a "better amp".

Any experiences? Suggestions? Other options worth considering?

Thanks for your time and be safe.

Hi Atharva,

A Pass Labs Aleph 3 or 5 would be nice. I use a Aleph 3 and am very happy with it. I believe there are a couple part substitutions / upgrades that can be done relitively simple if you want to tweak it a bit. I believe there is only a couple resistors and 1 electrolytic cap in the signal path. The imput resistor could be upgraded to a Tantalum or wirewound and the cap to a Elna Silmic. Also Coda made a 25w Class A amp called Coda 2.5 pretty rare but also wonderful sounding amp.