I am researching possible amplifier kits to be used with an Orion type loudspeaker. As with the Orion, I would require either 6 channels with the woofers getting 100 watts or 8 channels of 60 watts or so.
I've checked out the AKSA 55 (and 100) and the ESP P3A. Both seem like good options and are within my projected budget (under 1500 US$). Has anyone had a chance to compare the two for quality of sound? Also, are there any other designs I should consider? I wish to have as good sonics as possible, though I've pretty much ruled out Class A amps due to the excessive heat (with a certain amount of regret).
Thanks.
Paul Ebert
I've checked out the AKSA 55 (and 100) and the ESP P3A. Both seem like good options and are within my projected budget (under 1500 US$). Has anyone had a chance to compare the two for quality of sound? Also, are there any other designs I should consider? I wish to have as good sonics as possible, though I've pretty much ruled out Class A amps due to the excessive heat (with a certain amount of regret).
Thanks.
Paul Ebert
millwood said:
Yes, I have checked them out and am still doing so.
I agree that there doesn't appear to be a big price differential. According to the $200 price for an ATI module, an ATI '1806' would cost $1800 and would be suitable, if not ideal. Mr. Linkwitz recommends the ATI 6012 since it provides 12 channels allowing one for each woofer which drives them better. But the 6012 costs $2k.
Part of the problem is the fact that I need either 6 or 8 channels, instead of 5 or 7 as the commercial products are typically configured. Going commercial basically limits me to 6 channels (except for the 6012). I then either have too much power for the mids and tweets or too little for the woofers. Otherwise, I'd just buy used. I may do that anyway if I find a good deal. I suppose I could limit the output to the mids and tweets using the Behringer DCX-2496 I plan to use.
I'm really stretching to save money here. My thought is to build the amps into the bottom of the woofer cabinets. That way, I may save on casework, cables and connectors. My current pricing has the P3A route costing me less than $1200 and the ASKA route between $1100 and $1400.
Paul
The AKSA is very well reviewed and is in kit form.
Altough I never built one I think it can be a excellent choice.
The P3A is also very good sounding, I've built a pair myself with off-the shelf components and it was comparable (altough less powerful) with the Holton's Symamp.
With an accurate component selection I tink it can take off, but if you aren't willing to experiment and to search go for the AKSA, Hugh Dean will thank you
and provide a complete kit.
Also Rod Elliot is very helpful, if you decide to go for the P3A, but AFAIK he only sells the PCBs (at a attractive price!), so the component choice is up to you.
Cheers
Andrea
Altough I never built one I think it can be a excellent choice.
The P3A is also very good sounding, I've built a pair myself with off-the shelf components and it was comparable (altough less powerful) with the Holton's Symamp.
With an accurate component selection I tink it can take off, but if you aren't willing to experiment and to search go for the AKSA, Hugh Dean will thank you
and provide a complete kit.Also Rod Elliot is very helpful, if you decide to go for the P3A, but AFAIK he only sells the PCBs (at a attractive price!), so the component choice is up to you.
Cheers
Andrea
Hi Paul,
IMHO.
I have both the AKSA 55 and Elliott P3A amps. Both are good amps. I built them using exactly the same power supply and output transistors so I could get a direct comparison. I was interested in their different design philosophies, ie EF vs CF output stages, different constant current feed cct, and generic components vs higher quality components.
The AKSA is well burnt-in as it is over 18 months old now and the P3A would have had a few weeks burn-in. The AKSA is built with components supplied by Hugh and the P3A is build from generic components (other than the output transistors).
While I find it difficult to put in words the difference between the two amps, suffice to say, the last time I plugged the AKSA in, I promptly logged onto the net and bought another one with the Nirvana upgrade.
For more info on the AKSA see http://www.audiocircle.com/circles/viewforum.php?f=19
IMHO.
I have both the AKSA 55 and Elliott P3A amps. Both are good amps. I built them using exactly the same power supply and output transistors so I could get a direct comparison. I was interested in their different design philosophies, ie EF vs CF output stages, different constant current feed cct, and generic components vs higher quality components.
The AKSA is well burnt-in as it is over 18 months old now and the P3A would have had a few weeks burn-in. The AKSA is built with components supplied by Hugh and the P3A is build from generic components (other than the output transistors).
While I find it difficult to put in words the difference between the two amps, suffice to say, the last time I plugged the AKSA in, I promptly logged onto the net and bought another one with the Nirvana upgrade.
For more info on the AKSA see http://www.audiocircle.com/circles/viewforum.php?f=19
My small collection of Aussie amps includes a P61 (early 55W AKSA, no longer available, my version uses non standard transistors), a 100W AKSA Nirvana (dual mono) and P3A (dual mono with Sanken output transistors, Toshiba drivers + VAS and proper power supplies).
The 55W amp sounds sweet, clear and musical but has insufficient grunt for medium or low efficiency speakers with extended bass response. It works very well as the treble amp in an active system.
I marginally prefer the sound of the P3A to the AKSA 100N. Both are capable of very good sound quality, the AKSA is slightly warmer and more colourful (coloured?) the P3A is clearer and more controlled at the frequency extremes. OTOH, I believe I saw a post by Nelson Pass stating he marginally preferred the AKSA and he has collosal amounts more audio cred than me!
To put this into perspective the AKSA and P3A are vastly superior to a Linn LK140 (UK£750) I used to own, they also outperformed a Lindsley Hood 80W Mosfet amp and various Borbely imposters I have built.
Please also note that unlike Greg's my P3A has (what I would consider to be) a better power supply than the AKSA 100N.
Dave
The 55W amp sounds sweet, clear and musical but has insufficient grunt for medium or low efficiency speakers with extended bass response. It works very well as the treble amp in an active system.
I marginally prefer the sound of the P3A to the AKSA 100N. Both are capable of very good sound quality, the AKSA is slightly warmer and more colourful (coloured?) the P3A is clearer and more controlled at the frequency extremes. OTOH, I believe I saw a post by Nelson Pass stating he marginally preferred the AKSA and he has collosal amounts more audio cred than me!
To put this into perspective the AKSA and P3A are vastly superior to a Linn LK140 (UK£750) I used to own, they also outperformed a Lindsley Hood 80W Mosfet amp and various Borbely imposters I have built.
Please also note that unlike Greg's my P3A has (what I would consider to be) a better power supply than the AKSA 100N.
Dave
Paul,
As an alternative how about a modified ART SLA-1? PeAK has a good overview at www.angelfire.com/ca/rchau/audio/sla-1.html#1.3
Donald Nance does a modded version for $1200 (you still have to buy and supply the SLA-1!). As DIYers, surely we must be able to get somewhere between (in the performance stakes) for a lot less $$$$?
Brian
(No connection with ART or DN; just a very happy modified ART DI/O owner who is considering an SLA-1 )
As an alternative how about a modified ART SLA-1? PeAK has a good overview at www.angelfire.com/ca/rchau/audio/sla-1.html#1.3
Donald Nance does a modded version for $1200 (you still have to buy and supply the SLA-1!). As DIYers, surely we must be able to get somewhere between (in the performance stakes) for a lot less $$$$?
Brian
(No connection with ART or DN; just a very happy modified ART DI/O owner who is considering an SLA-1
)
David,
Thank you for your post comparing the two power amplifiers.
The AKSA uses 9,400uF per rail per module on the 100W Nirvana, and ultrafast soft recovery diodes. Considering the P3A uses the same capacitance, and a run-of-the-mill, 35A rectifier bridge, but a back-to-back diode/10R resistor/100nF cap all in series between signal and power earth.
I am guessing, but would like confirmation, that it is the diode/R/C link between power and signal earth which you believe makes the P3A supply 'superior'.
Have you tried the UFSR diodes against a conventional 35A bridge? I believe you would be surprised, though I suspect you have already,
Cheers,
Hugh
Thank you for your post comparing the two power amplifiers.
The AKSA uses 9,400uF per rail per module on the 100W Nirvana, and ultrafast soft recovery diodes. Considering the P3A uses the same capacitance, and a run-of-the-mill, 35A rectifier bridge, but a back-to-back diode/10R resistor/100nF cap all in series between signal and power earth.
I am guessing, but would like confirmation, that it is the diode/R/C link between power and signal earth which you believe makes the P3A supply 'superior'.
Have you tried the UFSR diodes against a conventional 35A bridge? I believe you would be surprised, though I suspect you have already,
Cheers,
Hugh
Hi David,
I'd be interested in a bit more details on your power supplies for the P3A. I'm always interested in trying a few new things. I'm guessing you didn't build the standard P3A power supply.
How do the Sanken output devices compare to the Toshiba ones?
On a side note: One thing I don't understand is, I've found my AKSA 55 more than powerful enough to drive my inefficient 84db speakers. Even my LM1875 gainclones (< 20 watts?) are capable of driving my speakers to a level loud enough for day to day listening. Is 84db considered to be medium or low efficiency? Are my speakers incorrectly rated? Or does the fact that the crossover is only used on the tweeters make the difference?
I'd be interested in a bit more details on your power supplies for the P3A. I'm always interested in trying a few new things. I'm guessing you didn't build the standard P3A power supply.
How do the Sanken output devices compare to the Toshiba ones?
On a side note: One thing I don't understand is, I've found my AKSA 55 more than powerful enough to drive my inefficient 84db speakers. Even my LM1875 gainclones (< 20 watts?) are capable of driving my speakers to a level loud enough for day to day listening. Is 84db considered to be medium or low efficiency? Are my speakers incorrectly rated? Or does the fact that the crossover is only used on the tweeters make the difference?
Hi Hugh and Greg,
The P3A is built on the standard pcb with some track modifications to allow dual mono construction. I used different power semiconductors – the VAS transistor (BD140) was replaced by 2SA1360, the drivers (BD139, BD140) were replaced by 2SA1306/2SC3298 and the output devices are 2SC2922/2SA1216. The Sanken output transistors were used to enable 4 Ohm loads to be driven with 42V rails without resorting to paralleled devices. The power supply for each channel consists of a 225VA 30-0-30VAC toroid with MUR820 diodes (one bridge per rail) and BHC ALS20A 10,000uF 63V capacitors (one per rail). I found it necessary to add a 10uF capacitor across the Vbe multiplier to provide sufficient drive to the negative side of the output stage when driving low impedance or capacitive loads. Using a bench power supply with 1ft long leads the on-board decoupling capacitors (0.1uF) were found to be inadequate, resulting in oscillation into capacitive loads. I replaced these with 56uF 63V Panasonic HFQ capacitors (in the chassis this may not be necessary due to the close proximity of the main reservoir capacitors, however I left them in place). I also added an output inductor and resistor to ensure stability into highly reactive loads, without this the amplifier could be provoked into oscillation. No input coupling capacitor is fitted since my preamp’s output is capacitively coupled.
Greg - my comment about the power versus efficiency is not related to loudness, rather to subjective scale, power and depth in the bass. The AKSA 55 just is not as convincing here as the AKSA 100, even at medium volume levels. I have not compared the Sankens to the Toshs directly (in an identical amp), so I don't feel able to state the differences athough I can conclude it's possible to get both to sound excellent. BTW how does the AKSA compare to the gainclone? - I gave up with chip amps after getting average results from TDA1541s.
Hugh - I did not use an RC snubber across the mains switch in the P3A nor are there any 10R ground lift resistors. I hope I got the grounding well sorted and therefore don't need the 10R resistors - there is certainly zero measurable or audible hum at quiescent.
Dave
The P3A is built on the standard pcb with some track modifications to allow dual mono construction. I used different power semiconductors – the VAS transistor (BD140) was replaced by 2SA1360, the drivers (BD139, BD140) were replaced by 2SA1306/2SC3298 and the output devices are 2SC2922/2SA1216. The Sanken output transistors were used to enable 4 Ohm loads to be driven with 42V rails without resorting to paralleled devices. The power supply for each channel consists of a 225VA 30-0-30VAC toroid with MUR820 diodes (one bridge per rail) and BHC ALS20A 10,000uF 63V capacitors (one per rail). I found it necessary to add a 10uF capacitor across the Vbe multiplier to provide sufficient drive to the negative side of the output stage when driving low impedance or capacitive loads. Using a bench power supply with 1ft long leads the on-board decoupling capacitors (0.1uF) were found to be inadequate, resulting in oscillation into capacitive loads. I replaced these with 56uF 63V Panasonic HFQ capacitors (in the chassis this may not be necessary due to the close proximity of the main reservoir capacitors, however I left them in place). I also added an output inductor and resistor to ensure stability into highly reactive loads, without this the amplifier could be provoked into oscillation. No input coupling capacitor is fitted since my preamp’s output is capacitively coupled.
Greg - my comment about the power versus efficiency is not related to loudness, rather to subjective scale, power and depth in the bass. The AKSA 55 just is not as convincing here as the AKSA 100, even at medium volume levels. I have not compared the Sankens to the Toshs directly (in an identical amp), so I don't feel able to state the differences athough I can conclude it's possible to get both to sound excellent. BTW how does the AKSA compare to the gainclone? - I gave up with chip amps after getting average results from TDA1541s.
Hugh - I did not use an RC snubber across the mains switch in the P3A nor are there any 10R ground lift resistors. I hope I got the grounding well sorted and therefore don't need the 10R resistors - there is certainly zero measurable or audible hum at quiescent.
Dave
Dave,
Thanks for the information. I think I have a clear picture of your P3A now. Sounds like your choice of transistors would make a difference over the generic ones I used. (I did use Toshiba 5200/1943 output transistors and I cut the PCB in half to make it dual mono.)
I have been using MUR860 in the gainclones (as recommended) but to be honest I couldn't tell much difference between them and a normal bridge rectifier. I haven't tried them on the AKSA or the P3A. The MUR820s you have been using do have a faster recovery time so I wonder if this would make a difference?
It would be interesting to compare a P61 AKSA with the commercial AKSA 55. I guess the difference in circuits, PCB and component choice would make a significant difference.
My simple gainclones aren't anywhere as good as my AKSA 55 or my P3A. OTOH I have heard Joe Rasmussen's tube buffered GC (JLTi) and in his system his does sound very good. Unfortunately I wasn't able to compare it to anything else at the time. The feeling I have at the moment, is to get a gainclone to sound really good you need to do what Joe has done and put a buffer and filter before the GC or another path is to use exotic and expensive caps and resistors. (or perhaps both)
Thanks for the information. I think I have a clear picture of your P3A now. Sounds like your choice of transistors would make a difference over the generic ones I used. (I did use Toshiba 5200/1943 output transistors and I cut the PCB in half to make it dual mono.)
I have been using MUR860 in the gainclones (as recommended) but to be honest I couldn't tell much difference between them and a normal bridge rectifier. I haven't tried them on the AKSA or the P3A. The MUR820s you have been using do have a faster recovery time so I wonder if this would make a difference?
It would be interesting to compare a P61 AKSA with the commercial AKSA 55. I guess the difference in circuits, PCB and component choice would make a significant difference.
My simple gainclones aren't anywhere as good as my AKSA 55 or my P3A. OTOH I have heard Joe Rasmussen's tube buffered GC (JLTi) and in his system his does sound very good. Unfortunately I wasn't able to compare it to anything else at the time. The feeling I have at the moment, is to get a gainclone to sound really good you need to do what Joe has done and put a buffer and filter before the GC or another path is to use exotic and expensive caps and resistors. (or perhaps both)
Just to Set the Record Straight
It's been quite a while since the earlier posts in this thread and I've done a lot more listening and some other changes to my system.
The P3A and ASKA are still fairly close in performance but I have to say that the AKSA is the long term winner. The P3A is more obviously detailed and dynamic, but also more 2 dimensional and has less tonal colouring. The detail and dynamics are still there with the AKSA but it's more subtly presented. Overall, the AKSA somehow has that extra magic that makes you want to keep on listening.
Dave
It's been quite a while since the earlier posts in this thread and I've done a lot more listening and some other changes to my system.
The P3A and ASKA are still fairly close in performance but I have to say that the AKSA is the long term winner. The P3A is more obviously detailed and dynamic, but also more 2 dimensional and has less tonal colouring. The detail and dynamics are still there with the AKSA but it's more subtly presented. Overall, the AKSA somehow has that extra magic that makes you want to keep on listening.
Dave
Dave,
I have 2 P61 PCBs on the shelf, I bought the board from ESP long time ago and I was too busy until now to work on it.
I see you have the same amp - and you are positive about performances. I would kindly ask if you could share some info with me, helping me to build a good amp.
Did you make any modification to the original project (different schematic, different components) ?
You can contact me at generali@mortara.com
Thanks,
Gianluca
I have 2 P61 PCBs on the shelf, I bought the board from ESP long time ago and I was too busy until now to work on it.
I see you have the same amp - and you are positive about performances. I would kindly ask if you could share some info with me, helping me to build a good amp.
Did you make any modification to the original project (different schematic, different components) ?
You can contact me at generali@mortara.com
Thanks,
Gianluca
Paul, you may also want to take a look at Sonnya's A1 amplifier using SMD parts on a four layer PCB. I think Sonny has exchanged an amp with Hugh, so we should see a review from Hugh soon, and also a review from Sonny on the AKSA... quite interesting. I'm certainly looking forward to their comments on the amps.
P61
Hi Gianluca,
I built the P61 from Rod Eliott's info on his website, this info has since been "pulled" at the request of Hugh Dean the AKSA designer.
I used the P61 as a tester to see if the AKSA could live up to its claims, the P61 showed real promise so I bought the official kit. I suggest you do the same, since the P61 has lots of the AKSA musicality but loses out on resolution, grip etc compared to the real thing.
Dave
Hi Gianluca,
I built the P61 from Rod Eliott's info on his website, this info has since been "pulled" at the request of Hugh Dean the AKSA designer.
I used the P61 as a tester to see if the AKSA could live up to its claims, the P61 showed real promise so I bought the official kit. I suggest you do the same, since the P61 has lots of the AKSA musicality but loses out on resolution, grip etc compared to the real thing.
Dave
P61
Thank you Dave for your advise.
I'll do the same, building my P61 according to the original instructions from ESP, and I'll give it a try.
The P61 should be good sounding enough to push me buying a "real" AKSA immediately after...
According to Hugh's description, the early P61 evolved into the current AKSA55 with improvements in quiescent stability and high frequency range transparency. Is that matching with your listening results?
Gianluca
Thank you Dave for your advise.
I'll do the same, building my P61 according to the original instructions from ESP, and I'll give it a try.
The P61 should be good sounding enough to push me buying a "real" AKSA immediately after...
According to Hugh's description, the early P61 evolved into the current AKSA55 with improvements in quiescent stability and high frequency range transparency. Is that matching with your listening results?
Gianluca
I have been reading through this thread with wonderment. 
The extraordinary aural perception of some denizens here is astonishing. They have picked up on some of the very subtle issues I considered in depth as I designed and voiced the AKSA.
It is significant that no-one has mentioned published distortion figures on the AKSA (which are pretty good, BTW) but rather have concentrated on the subjective. This is good, very good, since it relates directly to the audiophile experience. For myself, and of course YMMV, I have always felt that published specs on amplifiers are akin to describing the driving experience of an auto by reading the licence plate at 100 yards. A droll analogy, but close enough.....
My background is essentially tube (I still design for tubes), and I developed this amp from entirely conventional technology using common sense, public domain technology, and the human ear. Knowing that the world's 'best' amps were all developed in labs with expensive test equipment (overseen by Flint from Accounting), I resolved to do it my way - by ear. This involved topology, operating point, component choice and pcb layout. It is philosophy which determines the approach - and ultimately the product quality, and this applies to just about everything humans do. The work involved took rather longer than I expected, but has resulted in something which has some of the characteristics of tube amplifiers at a fraction of the price.
In deference to other designs, there are some very good ones out there, but none of the sonic qualities are evident just looking at a schematic....
Cheers,
Hugh
The extraordinary aural perception of some denizens here is astonishing. They have picked up on some of the very subtle issues I considered in depth as I designed and voiced the AKSA.
It is significant that no-one has mentioned published distortion figures on the AKSA (which are pretty good, BTW) but rather have concentrated on the subjective. This is good, very good, since it relates directly to the audiophile experience. For myself, and of course YMMV, I have always felt that published specs on amplifiers are akin to describing the driving experience of an auto by reading the licence plate at 100 yards. A droll analogy, but close enough.....My background is essentially tube (I still design for tubes), and I developed this amp from entirely conventional technology using common sense, public domain technology, and the human ear. Knowing that the world's 'best' amps were all developed in labs with expensive test equipment (overseen by Flint from Accounting), I resolved to do it my way - by ear. This involved topology, operating point, component choice and pcb layout. It is philosophy which determines the approach - and ultimately the product quality, and this applies to just about everything humans do. The work involved took rather longer than I expected, but has resulted in something which has some of the characteristics of tube amplifiers at a fraction of the price.
In deference to other designs, there are some very good ones out there, but none of the sonic qualities are evident just looking at a schematic....
Cheers,
Hugh
There is nothing simple in really good simple design
"none of the sonic qualities are evident just looking at a schematic..."
Or the distortion numbers or reviews for that matter. The devil is in the details. BTW the PCB design is one best audio PCBs I ever seen. Simple topology or not, this a very sophisticated amp and is the result of years of work. A very commendable design. There are hundreds of ways to screw up even a simple topology with poor PCB layouts, decoupling, and grounding choices. I see a tremendous amount of work and attention to detail and am surprised at the performance he has wrung out of simple and rather classic design approach.
"none of the sonic qualities are evident just looking at a schematic..."
Or the distortion numbers or reviews for that matter. The devil is in the details. BTW the PCB design is one best audio PCBs I ever seen. Simple topology or not, this a very sophisticated amp and is the result of years of work. A very commendable design. There are hundreds of ways to screw up even a simple topology with poor PCB layouts, decoupling, and grounding choices. I see a tremendous amount of work and attention to detail and am surprised at the performance he has wrung out of simple and rather classic design approach.
Fred:
soundwise I had the chance to compare the AX to the Aksa55 and other than better bass on the AX I couldn't tell the difference. It was a very crappy pair of speakers so I might have missed some major details in both the amps.
As Paul Sr. would say: considering the sleeker look of a 3in heatsink over a 20 in heatsink, lower building and operation costs compared to the AX I would call the aksa "ridiculous".
soundwise I had the chance to compare the AX to the Aksa55 and other than better bass on the AX I couldn't tell the difference. It was a very crappy pair of speakers so I might have missed some major details in both the amps.
As Paul Sr. would say: considering the sleeker look of a 3in heatsink over a 20 in heatsink, lower building and operation costs compared to the AX I would call the aksa "ridiculous".
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