[Kw6]

A well designed amp with PuriFi modules is sweet in the sense of having extremely low distortion and being load-invariant, meaning that it won't exhibit frequency irregularities when driving reactive loads. Since I find distortion and FR bumps to be as un-sweet as anything, I would call my amps sweet, though it's not a term I habitually use for audio gear. As an illustration, I can (and do) listen to decent commercial recordings of harpsichords, sopranos, and violins with pleasure. The amps are not sweet in the sense of having audible high-frequency rolloff or added warmth.

Some comparisons to other amps I've heard for weeks, months, or years: I consider the Apollon amps similar in tonality to the Bryston 4B3, Classe CA-2300, and AVA FetValve 400R. On the other hand, the Apollons are perhaps a little cooler than the Pass X250.8. (One person would say "less colored," another "less beautiful," but compared to a tube amp, the differences are small.) Despite its wide acclaim, the Sanders Magtech sounded cooler than neutral to me; the Apollon amps do not sound like that at all.

What I've noticed with the Apollons (and another "D" I tried) was remarkable clarity, which I like.

Good luck!

Thanks for sharing! Are you saying Apollon is closer to a tube amp without the high frequency roll off?

I went to Apollon website but since I am in North America  do you think Nad c298 will sound like your Apollon?

You also mentioned Apollon don't sound cool like Magtech. So they sound more like the new Bryston 4b3? BTW the 4b3 on Magneplaner 1.7i sounded great. Smooth full and airy!

[Kw6]

Ok gotcha! I was thinking of Adcom 565se but need long term reliability. I want camp to last at least 10 yrs. Btw I am not to talented enough to diy with active crossover!

[Chewbacca]

Ok thanks! But I heard Klaus was difficult to deal with!

I've had the exact opposite experience with him. I've dealt with him for about 8 years, and he's been a pleasure throughout! Always willing to go the extra mile, and not just in it to shake the money out of your pockets.

Yup, he can be a pain to get ahold of sometimes. He generally calls me back within an hour though. You're best off calling him later at night 6-9pm central time. Also - he's not Amazon Prime... You won't get your amps next day after your order. He's swamped with orders... but there's a good reason for that!

[Kw6]

Ok good  to know thanks!😊

[Mike-48]

Thanks for sharing! Are you saying Apollon is closer to a tube amp without the high frequency roll off?

I went to Apollon website but since I am in North America  do you think Nad c298 will sound like your Apollon?

You also mentioned Apollon don't sound cool like Magtech. So they sound more like the new Bryston 4b3? BTW the 4b3 on Magneplaner 1.7i sounded great. Smooth full and airy!

I meant that differences among the SS amps I listed were small compared to the difference a tube amp might make. That was not a value judgement (good or bad), just that tube amps, because of their typically higher output impedance, can vary a lot from speaker to speaker. Perhaps I should not have mentioned tubes at all, as I've not owned a power amp with tube output stage for decades.

Sorry, I don't know what the NAD sounds like. I would not assume that all amps with PuriFi modules sound the same, because there are other parts to the amplifier than the modules, and even aspects like parts layout can make a difference.

Yes, I was trying to say that the Apollons had tonality similar to the Bryston 4B3 (as far as sweetness or warmth), but with some additional clarity. The 4B3 is what I owned before buying the Apollons, so I have several years' worth of experience with it paired with the Janszens.

All the above, of course, is with my ears in my system. Others might not agree with my tastes.

It seems like your next step would be to make a short list and try to audition some of the contenders, in your own system if possible.

[tull skull]

Why is OTL better? I thought  transformers vat output like tube amps and McIntosh amps make ESL sound better?

Well there is no better really when you have a budget. You can choose what priorities matter most to you and go from there.

It really would help to know what speakers you have. Some amps work better based on what they see from the speaker load.

Also AUTOFORMERS can be your friend and are worth trying in your system.

Transformers are a big source of distortion. If you value low volume fidelity then OTLs are one of the best, along with DHT's. OTLs usually have simpler circuits and higher bandwidth. Simpler is usually better.

If I were going to simplify the description; they have a purity that is complimentary to stats.

you can read more about their advantages (and disadvantages) at the company sites I mentioned.

[Bemopti123]

Henry Ho's S250 Signatures.  Check out the reviews ,his amps were designed to deal with electrostatic speakers in mind. Class D with massive traditional power supplies. 

[twitch54]

Hi everyone!

Yes I have the Martin Logan Electromotion ESL!

easy speaker to drive, no need to sweat over too much. 50-100 watt 8 ohm rating and the ability to dbl down(SS topology) will be plenty

[Kw6]

I meant that differences among the SS amps I listed were small compared to the difference a tube amp might make. That was not a value judgement (good or bad), just that tube amps, because of their typically higher output impedance, can vary a lot from speaker to speaker. Perhaps I should not have mentioned tubes at all, as I've not owned a power amp with tube output stage for decades.

Sorry, I don't know what the NAD sounds like. I would not assume that all amps with PuriFi modules sound the same, because there are other parts to the amplifier than the modules, and even aspects like parts layout can make a difference.

Yes, I was trying to say that the Apollons had tonality similar to the Bryston 4B3 (as far as sweetness or warmth), but with some additional clarity. The 4B3 is what I owned before buying the Apollons, so I have several years' worth of experience with it paired with the Janszens.

All the above, of course, is with my ears in my system. Others might not agree with my tastes.

It seems like your next step would be to make a short list and try to audition some of the contenders, in your own system if possible.

Ok thanks for the clarification! If Purifi is close to 4b3 than what a bonus. Yes Apollon probably uses better input buffer but we don't know audible unless side by side  test. So for sure no hard unrefined lean sound. I kinda get that from my Nad c390dd but keep in mind I am using their Bluos dac. I have Denafrips Ares II which I feel is more analog sounding.And also probably adding a tube preamp.

[Kw6]

Henry Ho's S250 Signatures.  Check out the reviews ,his amps were designed to deal with electrostatic speakers in mind. Class D with massive traditional power supplies.

Ok I will try to Google that thanks 😊

[Kw6]

easy speaker to drive, no need to sweat over too much. 50-100 watt 8 ohm rating and the ability to dbl down(SS topology) will be plenty

Ok cool 😌

[Kw6]

Well there is no better really when you have a budget. You can choose what priorities matter most to you and go from there.

It really would help to know what speakers you have. Some amps work better based on what they see from the speaker load.

Also AUTOFORMERS can be your friend and are worth trying in your system.

Transformers are a big source of distortion. If you value low volume fidelity then OTLs are one of the best, along with DHT's. OTLs usually have simpler circuits and higher bandwidth. Simpler is usually better.

If I were going to simplify the description; they have a purity that is complimentary to stats.

you can read more about their advantages (and disadvantages) at the company sites I mentioned.

Ok I will research it as I thought OTL had a pure sound but lean and no bass!

[jsm71]

I also use the JansZen Valentinas that Mike-48 has.  They are a simple load as far as electrostatic loudspeakers go.  I use Linear Tube Audio's ZOTL40 amp.  It was the fourth amp I tried with these speakers and I'm done searching.  LTA licenses the ZOTL design from David Berning and support linear frequencies in both directions similar to SS, but with tubes.   https://www.lineartubeaudio.com/

The only SS amp I tried was a Sanders Magtech, left over from my days using Maggie 1.7s.  Lots of power, but totally lifeless sound with the JansZens. 

[Mike-48]

The only SS amp I tried was a Sanders Magtech, left over from my days using Maggie 1.7s.  Lots of power, but totally lifeless sound with the JansZens.

Interesting! I tried one, too, and I strongly disliked it with the Janszens. I found it cold and uninvolving. I was quite surprised, given the many rave reviews. It's one of those audio mysteries.

[Jazzman53]

The different types of commercial and DIY ESL's present different loads to an amplifier.

The most difficult ESL's to drive are large unsegmented panels like Martin Logan SL3's, many DIY types, and Quad ESL 57's; all of which present a totally capacitive load with huge phase and impedance swings.   

Slightly less difficult are unsegmented hybrid types like most Martin Logan and Janzen models.     

The easiest ESL's to drive are the Quad ESL-63 types which use segmented stators connected as an LC transmission line.  These are a predominantly resistive load.

The segmented line source types connected as an RC transmission line (the current state of the art in DIY types) present a load that's only partially capacitive and mostly resistive. 

Class D amps drive capacitive loads quite well but some consider their sound a bit sterile and lifeless.

I think a load invariant amplifier like a Sunfire or Sanders Magtech would be excellent choices for driving the more capacitive ESL's.   

I personally use class G amps (basically class A/B solid state amps with 3 power rails) and I never had any problems driving my older unsegmented hybrid ESL's or my newer RC segmented hybrid ESL's
         

[Don_S]

The different types of commercial and DIY ESL's present different loads to an amplifier.

The most difficult ESL's to drive are large unsegmented panels like Martin Logan SL3's, many DIY types, and Quad ESL 57's; all of which present a totally capacitive load with huge phase and impedance swings.   

Slightly less difficult are unsegmented hybrid types like most Martin Logan and Janzen models.     

The easiest ESL's to drive are the Quad ESL-63 types which use segmented stators connected as an LC transmission line.  These are a predominantly resistive load.

The segmented line source types connected as an RC transmission line (the current state of the art in DIY types) present a load that's only partially capacitive and mostly resistive. 

Class D amps drive capacitive loads quite well but some consider their sound a bit sterile and lifeless.

I think a load invariant amplifier like a Sunfire or Sanders Magtech would be excellent choices for driving the more capacitive ESL's.   

I personally use class G amps (basically class A/B solid state amps with 3 power rails) and I never had any problems driving my older unsegmented hybrid ESL's or my newer RC segmented hybrid ESL's
       

Jazzman53,

Thanks for the education. Where do current generation Sound Labs fit into that picture?

[Mike-48]

The different types of commercial and DIY ESL's present different loads to an amplifier.  [...snip...]

Class D amps drive capacitive loads quite well but some consider their sound a bit sterile and lifeless.

I think a load invariant amplifier like a Sunfire or Sanders Magtech would be excellent choices for driving the more capacitive ESL's.  [...snip...]

Great post, and I enjoyed reading about your system in your later message. The tech info on various types of stats (in the original post) was really interesting and useful.

The business about Class D amps sounding lifeless is an unfortunate bit of audiophile dogma, in my opinion. As you say, load invariant amps are excellent for capacitive loads, and the newer Class D amps are as load invariant as they come.

Of nine different amps I've tried with the Janszens, I liked the nCore and PuriFi based ones as much as any and more than most. The one that tied them was a Classé, but that had a noisy fan.

Your system sounds amazing and a lot of fun on your part. My soldering and construction skills started out mediocre and have not improved with age, so I buy things already made. I am a little jealous of those with a knack for building. I can only imagine that it adds a lot of satisfaction to getting great sound.

[Jazzman53]

Jazzman53,

Thanks for the education. Where do current generation Sound Labs fit into that picture?

I don't know much about the Soundlabs, and I've never heard them.  The following is only speculation based on what I can glean from the limited information given in Soundlab's sales brochures:

The stators appear to be vertical wires on plastic support grids.  And the grids appear to be arranged as many small flat cells, which are faceted in the vertical plane to approximate a curve, rather than an actual continuous curve like a Martin Logan panel.   

I suspect the Soundlab stators are unsegmented/high-capacitance because I see no reason to employ both curvature and electrical segmentation when either alone would suffice for dispersion.  And if so; the load would be predominantly capacitive and the impedance would fall linearly with rising frequency-- becoming <2 Ohms in the top octaves. 

Fortunately; most music doesn't have a lot of energy in the top octaves.  Even so; if the Soundlab panels are unsegmented (electrically), they would be a rather nasty load; requiring a robust and stable amp.

The interesting thing about the Soundlab speakers is how the diaphragm is segmented to use it's fundamental resonance (i.e. the "drum head resonance") to augment the bass output.  Whereas a large unsegmented diaphragm would have a single loud resonance peak over a narrow bandwidth; the Soundlab's diaphragm is segmented into many cells which become progressively larger from top to bottom, such that the drum head resonance is broken up into many smaller-amplitude resonances spread out over a wider bandwidth, and in a way that mimics the logarithmic energy curve of natural bass.  This is quite ingenious in theory but, considering that a resonance is by definition uncontrolled motion (hence; undesireable), I suspect the intent is not fully realized. 

Martin Logan likewise uses multiple unequal diaphragm segments to break up the drum-head resonance, except the diraphragm is tensioned very high to raise the resonance frequency and use it to augment the upper bass. 

Soundlab merely took this idea to a higher level of sophistication and bandwidth.

Among DIY hybrid designs, there are basically two schools of thought for dealing with the drum head resonance:
One school uses unequal, progressive diaphragm segments to break up and use the resonance (ala Martin Logan).

Another tensions the diaphragm lower and uses wider/equally spaced segments giving a single narrow resonance at a lower fequency, and then crosses the panel over to the  woofer at least one octave above the diaphragm resonance using a steep filter slope (at least 24db/octave via a digital crossover).  The intent here is to avoid exciting the drum head resonance by chopping of the energy to the panel significantly above the resonance.  This is the method I use in my DIY speakers.     

Jazz

[BruceSB]

Let me throw a power amp into the mix.
One that no one has mentioned so far.
I have been using a Quad 606 with my spectra 22s for 35 years and have been very satisfied.
I do however have a new power amp on order (but it has a 24 week wait!!) for my new electrostats.
I suspect that someone could get a second hand Quad 606 and get it re-capped for a very reasonable price.
Bruce

[Stimpy]

I also have Martin Logan Electromotion ESL speakers.  They don't seem too difficult a load.  I've used my Adcom GFA-5400 without issue.  I now use an Aragon 2004 MK ii, and that works very well.  The Adcom is a bit more warm and spacious, but the Aragon sounds more neutral, with better high end extension, with good micro detail.