What Amp do you use with your Mark Audio Drivers?

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I may be minority here but I am powering my A7.3 on a wall mounted MLTL with a very low cost but great sounding class AB TDA7297. $5 amp but sounds fantastic.


I'm using my Folsom DIY7297 with some CHP-70's I got off Craigslists in some pretty decent plywood boxes. I'm taking advantage of boundary reinforcement a little for bass. But overall it's a very nice match. The little MA's are very articulate with it. Right now I'm listening to Caribou, which is electronica, and I'm not disappointed with the bass. No it's not big heart throbbing, ground pounding, but it is still very pleasurable. To be honest, most the time I don't want to have super-blasting bass anyways. In contrast an FE126en flops on it's face and make like zero bass with the amp, even in a compression loaded back horn...

The one comforting factor is that peaks of 24w aren't going to ever crinkle the drivers.
 
At the risk of repeating what others may have replied: The Pass designed Amp Camp Amp. I use the original version to power MA Alpair 12P Pensils for a great result, also use it on my MA Alpair 10P in a Brine's BR bookshelf cab.

I'm waiting with baited breath to buy the new version of ACA when it comes back in stock.

Mario
 
Founder of XSA-Labs
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Try the Alpha 20. Easy to build and operate adjustment feee Class A amp by Aksa. No unobtanium parts (all low-cost in stock parts on Mouser/Digikey) and it sounds fantastic. Circa 0mV DC offset from cold to hot - not a pot to adjust. Bias is rock stable courtesy Pass Aleph CCs. UMS compliant and uses any standard Pass Fx series PSU. Early Proto has pot but not needed will replace with fixed resistor in subsequent ones.

Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier

661735d1518324741-aksa-lender-mos-hybrid-aleph-alpha-amplifier-alpha20-amp-build-02-left-jpg


30dB gain so doesn’t need a Preamp to reach clipping from a basic source.

Here is FFT for 1w into 8ohms:
661737d1518324741-aksa-lender-mos-hybrid-aleph-alpha-amplifier-alpha-20-2-87vrms-8ohms-fft-png
 
X that amplifier looks good but I have a few worries.
1. i live in the tropics average temp 30-35C in the afternoon so wont the amp sort of make my room hotter?
2. dont speakers sort of have distortion around 1%. would 0.017% be overkill or are we measuring the wrong thing since i think you mentioned that these amps represented a jump in performance
thank you for your contributions in these columns
 
Founder of XSA-Labs
Joined 2012
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X that amplifier looks good but I have a few worries.
1. i live in the tropics average temp 30-35C in the afternoon so wont the amp sort of make my room hotter?
2. dont speakers sort of have distortion around 1%. would 0.017% be overkill or are we measuring the wrong thing since i think you mentioned that these amps represented a jump in performance
thank you for your contributions in these columns

In stereo it dissipates about 150w - like a couple of 75w incandescent bulbs. If you open a window or have AC it’s not a problem.

It’s not the low THD but the harmonic profile of dominant 2nd order, less 3rd and a monotonic decrease or better yet, absence of higher orders. You can hear the difference between 0.05% and 1% THD that’s for sure. 0.05% to 0.005% harder to tell except for trained ears with well known passages. But ultra low THD of 0.00002% a hives with massive negative feedback and lots of odd order and higher orders of harmonic distortion is audible as fatiguing and harsh sounding, and perhaps sterile and devoid of emotion. These are very subjective terms of course - but that’s the general sentiment from those who have heard SE Class A amps.
 
X that amplifier looks good but I have a few worries.
1. i live in the tropics average temp 30-35C in the afternoon so wont the amp sort of make my room hotter?
2. dont speakers sort of have distortion around 1%. would 0.017% be overkill or are we measuring the wrong thing since i think you mentioned that these amps represented a jump in performance
thank you for your contributions in these columns

That's what so nice about the 7297, if the heatsink is exposed on the back it won't even get warm. One guy in Indonesia specifically uses it during the summer.

The 7297 is influenced greatly by the source, so it changes a lot based on the source used. That is a good and bad thing.
 
I've got my 7.3eN driven by a Bottlehead Stereomour 2a3-based SET (3.5w), and the 12pw driven by a Crown XRS1500 Class D amp rated at 350w. All drivers in Planet10 designed enclosures, and both amps controlled with an AES AE3 preamp. I am using a passive line-level crossover for each, and with the inline resistor for the low-pass on the 12pw, the power is actually surprisingly well matched. I'm getting all the SET sweetness out of the 7.3, and the Class D has all the power I'll ever need for the low end.

The sound overall is sublime.
 
I can only speak from my own observations, but transformer ended amps seems to work the best. I have a Prima Luna Prologue 4, a Marantz PM5004, a diy hypex module amp of 5 years ago (that i actually don't use anymore) and a Luxman 5M21 that i recently sold. And my Alpair 10.3M gen 3 in ported speakers sound by far the best with the Prima Luna Prologue 4. I also used it with a (low end tubeamp) Dynavox VR70 of a friend, and even that sounded better than the Luxman amp (wich should be on the higher end) and the small Marantz. I did test it with a custom build SE of a friend with an KT77 and a 6922 driver and that the best amp i heared on them.

The transformer does let the driver/speaker sound more balanced. I don't know if there is a technical explenation for it, but that is my experience. I use my 10.3M daily with my Prima Luna (35w trough 2x EL34 in PP per channel) now.
 
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waxx transformer cores have hysteresis. i suggest the hysteresis(which is frequency dependent) is absorbing the higher harmonic distortion hence your observation. you are using a tube amp which has dominant 2nd harmonic distortion which is in line with what X proposed as good sounding. X should be able to test this but i do not know if the extra losses will not wipe out desired sound detail that others in this forum suggest as important
 
Thank you X for the detail you put in the amplifier circuit. i have sort of run out of heatsinks i can find at 140watts at idle. at 2 amps idle the final stage losses is already 100 watts/channel. can understand why some people would prefer tubes.
but you did say .05% thd is another target. what final stage idle current do i need to get .05% thd.
Thank you
 
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