FYI, for anyone following this thread, I've decided to sell my Atoll IN200 SE. If you're interested, feel free to p.m. me.
suggestion for a SS class AB amp that sounds like a class A ... if such a thing exists
Looking for an amplifier below 2K for my Altec 620A (99 db efficiency). My actual amp is a Sugden A25B, which has 34 watts/chanel in class AB. Although quite musical, it lacks transparency and details. Of course, the best amplifier would be tube or class A but I'm trying to avoid these because of the heat and the electricity bill (my amp is on all day long). My short list include :
NOTE : please, no class D since I'm not familiar with it (and pretty skeptic too).
- Audio by Van Alstine Set-120
- Ayre AX 7e (used)
- Sugden Mystro (class AB)
- Benchmark AHB2 (used)
NOTE : please, no class D since I'm not familiar with it (and pretty skeptic too).
61 responses Add your response
The Benchmark distortion at low power, i.e. where crossover distortion comes into play is every bit as good and probably better than most Class-A. Same would be true of several new Class D amps.
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Thank you all for your suggestions ... they are greatly appreciated ... I am researching each of them and added to my list the Belles Aria, Plinius 8100, Portal Panache and Odyssey khartago ... Apart from the Belle Aria, all have 100 watts / channel (or more) ... as my speakers are 100 db efficient, I won't use all that power ... my current amp is 34 watts / channel and it can drive my Altec hard enough ... I'd rather have a great sounding amplifier of 50 watts (plus or less 10 watts) than a 100 watts (or more) ... thanks! |
a SS class AB amp that sounds like a class AThis thread is going nowhere. As it doesn’t address the OP’s thread title Nothing repeat nothing! solid state A/B (low bias A) sounds like a 20w> high bias Class-A amp. As there is no xover distortion in Class-A when the top and bottom transistors switch over from each other, because they’re still both biased into Class-A. The transistor xover distortion is most noticeable in the highs, (strings, piano, tops of female high notes etc) on a low bias Class-A/B amp when it switches to B, after a couple of watts. You need around 20w of Class-A to make it disappear on a A/B amp, then it gets too hot because of the rail voltage to get it to be 100w in Class-B. The A’s heat goes up exponentially. compared to just having a 20w class-A push pull with no Class-B So go back to my first post, bi-amp with a simple 20w Class-A for the highs (no B and not very hot). Then an A/B for the bass. https://forum.audiogon.com/posts/2065044 PS: last weekend we listened to Wilson Alexia MkII’s driven by a Class-A/B Gryphon Antillion Evo (it’s got 3 Class-A bias settings 10w 30w and 100w, switchable on the fly), we were listening mainly to streaming v cd, and at the end of the session we decided to go from 30w to 100w, all of us heard the improvement within seconds, and felt the room heat up after 1/2hr. (Didn’t change the streaming v cd outcome though). Cheers George |
Not as well know, but I recently acquired an LFD LE VI. Hand built in UK Extremely smooth and liquid, kick ass bass, and pleasent top end. 50 solid watts of AB, drives my 84 db spendor A4s with absolute ease. It would really pack a punch in some sensitive speakers as mentioned. Think, handbuilt smoother sounding Naim. |
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@jtgofish +1 On the other side of four Class A amplifiers, I found the amps I was looking for, and they run in Class AB. Class A amplifiers are not necessarily better than anything else and maybe not with all speakers or on all music. Decide what sonic attributes you value most and then find an amplifier that delivers those while providing enough power to really make your speakers really come alive. |
@ decooney according to the Altec catalogue, their sensitivity is 100db with 1 watt at 4’ on axis... when I had VOT (A-7), I had a pair of 14 watts Leak mono tube amps and it was plenty... and the VOT we’re 101 db... so yes, a low wattage amp if fine... Any thought on the Audio Sector products (gain clone) ? |
alaindexe’s Altec 620A speakers are close to 100db sensitivity @1w, 4-feet away, right?. Can operate well with two (2) really good watts. Low watt delicacy of targeted 20-30w musical amplifiers like Firstwatt, Sugden, Pucini sound would be the ticket for these speakers. Quality watts needed more than quantity watts in this case. @ebmGood grief, is that 28 Mosfets (14 per side) in that Stremento #4? 250/500 watts? https://www.hifinews.com/images/719audia.ins.jpg |
The BellesAria is 75watts, is really open sounding and has good grip on the bass. Its a beefy 75 watts for sure. It might be slightly rolled off on top but has a nice warm sound that is not fatiguing at all. It is lightweight and unassuming but is of great quality. @hilde45, the inside of that atoll is top notch 👍 |
@zm Thx... the Pucini was on my list for quite some time... but after reading reviews about it, I concluded that it was pretty similar to my Sugden... |
@zm Which FirstWatt model are you comparing to? Each of them have a different circuit topology and output transistor types, SE, PP, different impedances, and wattage power output. Interested if your AA Pucciini sounds more like a SIT-3, F6/F7, or J2, etc. Also dependent on what preamp you are using too. Thx. |
I have an Audio Analogue Puccini Settanta Rev 2.0 that compares very favorably to the class A amps I currently own (Line Magnetic, First Watt). It is by far the most euphonic solid state integrated I’ve had (others would say “colored”), extremely warm and rich in the midrange. Not the last word in transparency, of course. A brand that flies under the radar here in the states, but a beautiful sounding amplifier IMO. Hand made in Italy, first rate build quality. |
@decooney I hear you... I used to have very good cross overs that a friend did for me, when I had Altec Stonehenge III (also with a 604 8G)... they we’re made with oil condenser and military grade parts and weighed about 20 pounds each... they we’re SO MUCH better then the junk that came with the 620A... I’ve been missing them greatly ever since... I sold the Stonehenge III because the inner volume of the enclosure wasn’t sufficient... I had to sell the cross over as well in order to get the money to buy the 620A... it was heart breaking because I built them myself (they were grooved)... but the 620A are MUCH better since they have the perfect volume for the 604 8G... |
@alaindexe FYI, for some added inspiration - peeking over on the DIYaudio site, members were commenting about before and after results from upgrading and refreshing the old Altec 604/620 crossovers with GPA crossovers and replacement parts. Quote, "it added a sense of spaciousness and clarity to the speakers", unquote. |
Extra long speaker cables and extra long interconnects with high capacitance can be impactful. Particularly as noted earlier when gear/voltages are not designed to be used with long runs. A simple test is to pull all the gear super close together in a room, even with short low grade cables, make everything super short (for a test). Listen and see if you can hear any difference. |
@audioguy85 : my place gets way too hot in summertime to use a class A... also, it seems pretty irrational to me to waste so much electricity... I was told by a tech that what damages an amplifier was everytime you turn it on and off... when an amp consume very little at idle (or on a stand-by mode), why not simply leave it on all the time? |
In taking a closer look at your setup I noticed the Sugden only has single-ended inputs and you’re running a 12’ interconnect between it and your DAC. I’m not sure how much impact this might have on your sound or if the Benchmark has the juice to push the signal that far without it degrading, but if I was running interconnects that long I’d be using balanced interconnects — obviously not possible in your case. Maybe others can opine more in depth about this, but just thought I’d bring it up as a potential issue. That aside, I think you’re pursuing something of a unicorn given what you’re looking for at under $2k and excluding both Class-A amps and tubes. |
alaindexe OPGreat way that will sound very good, would be a $799 Schiit Aegir 20w Class-A for the highs and a $699 Schiit Vidar 100w a/b for the bass, horizontally bi-amped. Which if you look at the Altec xover is a snack to do. Before http://i10.photobucket.com/albums/a137/actke/Capture2_1.jpg After https://ibb.co/jVpKGvy You will need though a Schiit $49 Sys passive on the Vidar input as it has more gain than the Aegir and needs to be lowered just a bit, and this will allow you to tune the sound a little to your room or yourself. https://ibb.co/SwfGBm5 Cheers George |
Why not just buy a class A integrated and turn it off when not in use? Why are you leaving it on 24/7? I have a sugden A21se and am very happy. I hardly notice an increase on my electric bill. It’s no different than leaving maybe 2 60 watt bulbs on for long periods, ok maybe 3 60 watts....🙄. When not listening I turn it all off. It only takes about 30 minutes for mine to completely warm up and sound its best. This question reminds me of another on here....mainly, what dac sounds most like analog....ugh, you know my answer to that one.... |
The Benchmark will be by far and away the least class A-sounding, so delete immediately from your list. That's an interesting comment, since Class-A "sound" is far more influenced by design goals. A low feedback Class-A will have much different distortion products versus Class-A with more feedback, and that is not even taking into account voicing. If someone makes a transparent sounding Class-A, i.e. neutral, not voiced, and no intentional distortion, then it would be closer to the Benchmark who has very low distortion at low power, somewhat negating any advantage of say Firstwatt and the justification for most ClassA, i.e. removing zero crossing distortion. |
No worries, @alaindexe , all in good collaboration - you have a nice amp and speakers worth investing in. Fwiw, a few years back, helped a few locals to spec/design/build some very large Altec (Onken, custom) fridge size speakers (3 pairs). It was another new learning experience, before & after results with updated crossovers and GPA updated drivers, along with some other JBL drivers in another project. Listened to two pairs driven by 2-watt to 8-watt true class A amps. The results were beyond expectations. Much of the credit went back to the upgraded speaker components. |
@decooney : yes it’s an original A25B... and I just change the Alp potentiometer (with an original part - no worry)... I will eventually have to change the caps on this one... The Altec 620A is the enclosure model... speakers are 604 8G (Alnico magnet) ... never heard of surrounding becoming stiff with that kind of speakers... but the cross over needs work, that’s for sure... I’ve wanted to upgrade it for quite some time but it’s quite an investment.... I know of Great Plain Audio, thx... The Sugden is a great little amp... As I mentionned before, it does play quite well with my vinyl set-up... but it still isn’t as transparent as my previous amp, a CM lab 911 that I got rid of because it required too much maintenance (I had it entirely rebuilt twice). I bought the Sugden because I need an amp until I got something to replace the CM lab but end up keeping it... Even if I were to get something else, I’d probably keep it as a back up amp... thx for taking the time to kick my a--... and sorry for not selling the Sugden : ) |
@alaindexe alaindexe, Thx, we will see. Said the old way, "the proof of the pudding is in the eating". Disclaimer: Assuming your current amp is factory original Sudgen and not a copy clone, some have copied that circuit in the A25B, read on if interested. "Transparency" and "details" is the Goal, correct? Was thinking before you move past the cool Sudden A25B amp, are your Altec 620As original, 43 years old? Old dried up caps in the crossovers? Time for updated crossovers, maybe? Speaker surround stiff, maybe needing a refresh or proper update. As many like to say, start with the speakers. It applies here too, worth re-checking. Contact these guys, maybe send them your crossovers inside your speakers or send your crossovers and the speaker drivers, both. If you are not sure, have a local shop pull it all for ya, box it up, ship it out. Hey, gotta tell ya...You might love that "musical" Sudgen amp all over again with some other upgrades first starting with your speakers, then some good speaker cables and really good IC interconnect cables after, wallah! A modern speaker crossover update, with really good parts can be transforming for a 40+ year old speaker. Followed by great cables after. If this does not interest you, and you "MUST" jump right now and go buy another amp, send me a message, maybe I’ll take that Sudgen amp off your hands so you can go buy another amp - which might NOT help gain you more transparency. Maybe start here as option-B, just a thought. Root cause analysis can truly pay off some times, start here just for grins :) https://greatplainsaudio.com/jeff-markwarts-corner/ |
You can get a used Unison Unico Due Integrated for under 2K. https://powermodules.com/aria-integrated |
@onhwy61 it is true that when I play vinyl, it sounds much better although I don’t have a truly high-end turntable. I just have an old Garrard 401 with an Ortofon OM 20 and it does sing... I guess I’m gonna have to refigure my whole setting... this won't be easy since my computer is on the opposite wall from my system, and my room, 14’ long... |
@hilde45 ... thx for the picture... the model I look for wasn't the same, it was the IN 100 so my comment may not apply to yours... in one article I read (I forgot which one) the reviewer explained that the chassis was made of pretty thin metal and that it bent when he was plugging the cable at the back... this is a problem I've had with my Hafler DH 101 and it usually isn't a good sign... |
