Mark Audio Alpair 12P with current drive

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
Ah yes, takes me back 13 years to the current source F1 and F2.

Nice amplifiers and sold quite well. There is so much new excitement about
CS amplifiers that maybe I'll offer a kit in the DIYstore.

But do understand, in my own testing, there are very few instances where
a CS amp is seen to lower the distortion in a loudspeaker. Most of the time
the distortion increases a bit.
 
Ah yes, takes me back 13 years to the current source F1 and F2.

Nice amplifiers and sold quite well. There is so much new excitement about
CS amplifiers that maybe I'll offer a kit in the DIYstore.

But do understand, in my own testing, there are very few instances where
a CS amp is seen to lower the distortion in a loudspeaker. Most of the time
the distortion increases a bit.

Coming at this build from another angle: what's the amplifier you'd recommend for a Markaudio TL (like the oft-build Pensil series)?
 

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
I own most of the MarkAudiio drivers, and they are quite neutral and easy to
drive, which opens up a whole world of prospective amplifiers. 5 - 20 watt
single-ended Class A is my choice if you want to "sweeten them up".

They behave themselves nicely with CS amps, which bump the bass up
a bit with sealed or TL enclosures. Of the transmission lines, the old Bailey
designs are favorites, but that might reflect the fact that I cut my teeth
on them at ESS when I was 21.

:geezer:
 
Nelson, - certainly all of the Alpairs and CH series we've played with so far on the ACA ( DIY Audio kit version was a bargoon) sound wonderful.

I've heard rumors, but likely missed the actual facts on the subject, but would you be aware of status / progress on the Son of ACA, or whatever it'll be named?

A CS kit could also be fun - and just when I thought I was almost burnt out by this hobby :D

Lohengrimas, I'm quite a fan of the Pensil series -probably mostly with A10.3 as the size and tonality work well for me, and if not in a hurry, I'd be inclined to await Nelson's answer to the above. I've also heard various Alpairs in my system with Tom Christiansen's Modulus86 - very nice, but not a SE Class A.
 
What is lacking in the Pluvia 7 drivers?

The P7s althou voiced similarily to the A7.3 are not as capable of reproducing the very small detail (ie P7 does not have as large a DDR as the A7x). Of course to realize the difference, the supporting equipment has to provide that detail to the speaker and the listener needs to have the training/ear/brain sensitivity to perceive it when it is there. ie the P7 is very good value and for many the step up to the A7 will gain them nothing.

dave
 
The P7s althou voiced similarily to the A7.3 are not as capable of reproducing the very small detail (ie P7 does not have as large a DDR as the A7x). Of course to realize the difference, the supporting equipment has to provide that detail to the speaker and the listener needs to have the training/ear/brain sensitivity to perceive it when it is there. ie the P7 is very good value and for many the step up to the A7 will gain them nothing.

dave

Can the DDR be found in the T.S. parameters?
What kind of amp do you recommend Dave for the MA drivers?
I guess your answer to this last question of mine will also answer your last statement: "the P7 is very good value and for many the step up to the A7 will gain them nothing."?
 
I hav enot yet seen anyone demonstrate a way of measuring DDR, so you won’t find it in the T/S.

The Alpairs deserve to be driven by the best amps possible.

Nelson’s ACA is good (and dirt cheap) and likely speaks for the voracity of many of his bigger amps, i have heard good tube amps (SE & PP) and shades of grey in Class AB SS amps. I’d love to get my hands on a Firstwatt S2… S3 coming soon? Many amps that should do the job… even some of the newer HT receivers, i know Chris’ big Onkyo does a decent job.

dave
 

kp93300

Member
2007-03-21 7:00 am
Coming at this build from another angle: what's the amplifier you'd recommend for a Markaudio TL (like the oft-build Pensil series)?

I have 12P in superpensil
I have paired with Joe Rasmussen current amp.
The driver donot work well and distorts with moderately heavy bass.
I sealed the outlet with thick sponge used in washing car. The sound is transformed and is quite well balanced. the mid and high frequency are very nice also.
Of late, I discovered that the lunch box amp with TDA 7297 works extremely well in my 200 sq ft room. Bass is even better and more well controlled with excellent pitch of cello bass.

regards
kp93300
 
Time to fess up - and this'll be news to him, but one of the numerous kit projects long dormant in Dave's basement awaiting time and materials to finish off was an early version of the Hypex UcD180 amp modules, along with parts for a linear supply. After being quite satisfied with an earlier project for my upstairs system that consisted of a Sure 4-channel board and cheap Meanwell SMPS, as well as hearing Tom Christiansen's delightful litte LM386DR with SMPS last year, I bit the bullet and completed this build with Hypex's own SMPS400 and a gorgeous little chassis from HiFi2000 via the DIY Audio store. I wanted this to be as close to what a factory build / kit of theirs would sound like, and although hand cutting all the holes in the aluminum chassis took the most time, it was pretty much a snap to assemble.

So in addition the the Onkyo surround receiver that Dave mentioned, all told I have a collection of at least 5 makes/ models of classD / T amps in my harem, all of which I've played with on my two systems. The upstairs system has remained unchanged for a couple of years now, and is a 2 way variant on Castle microtowers with CHBW70 and ERT26 tweeter (paper and soft fabric dome respectively), while the downstairs 7.1 system has seen at least half a dozen main and center channel speakers flow through the testing process. Currently it's all MA drivers, 6 channels of metal, and the center is paper.

My observations to date of the degree of synergy between the various amps and speaker models would be that while my hearing is sufficiently aged and occupationally damaged to not detect the same degree of "issues" in the higher frequency range on the Hypex amps that a couple of close friends have observed, it was still a bit "gnashy" to my ears on either the A10.3 Pensils, or Alpair MTMs with A7.3 operating from about 300Hz up (and if that don't make it a mid-tweeter in some folk's lexicon, I'll politely disagree). Much less so on the upstairs paper / fabric dome 2ways. It (Hypex) does however deliver the best bass I've had in my system - both on the dual A12PW section of the MTMs, and with the by some standards fairly modest woofers in the 7.1 system. OTOH, while none of the lower powered units - cheapie little Yuang Jing TPA3116, Sure (TKA2050?) , Kingrex T20 or Virtue had the balls / dynamics / grip (pick your favorite buzz-word) on the bottom end as the UcD180, neither did any of them demonstrate the same issues with the higher frequencies. The front end for the 2-channel auditioning was Rotel RC1570 - a fairly decent preamp for someone too lazy to build one, and either Rega3 with AudioNote MM cartridge, or Apple TV streaming to optical input, balanced line out to the Hypex. On the Onkyo receiver, the LFE output is RCA only, so it's pseudo balanced out to the Hypex.

Of course, it's been probably a couple of years now since I've heard the ACA in my system, and I've not tried the A7P or any of the other paper models recently, so YMMV and all the usual caveats apply.
 
… the numerous kit projects long dormant in Dave's basement awaiting time and materials to finish off was an early version of the Hypex UcD180 amp modules, along with parts for a linear supply. After being quite satisfied with an earlier project for my upstairs system that consisted of a Sure 4-channel board and cheap Meanwell SMPS, as well as hearing Tom Christiansen's delightful litte LM386DR with SMPS last year, I bit the bullet and completed this build with Hypex's own SMPS400 and a gorgeous little chassis from HiFi2000 via the DIY Audio store...

Consider me gobsmacked that you completely this with such Apple-like secrecy. I would have approved of the use of SMPS, and now i want to listen to them!!!

dave
 
I have 12P in superpensil
I have paired with Joe Rasmussen current amp.
The driver donot work well and distorts with moderately heavy bass.
I sealed the outlet with thick sponge used in washing car. The sound is transformed and is quite well balanced. the mid and high frequency are very nice also.

What you did with your Pensils with the extra damping is to push them further towards aperiodic. This could be concisely done with even greater impact by optimal internal damping as well as damping the terminus.

This is the same as would be advised to anyone using a current amp to maximally damp down the resonant peak.

dave
 

kp93300

Member
2007-03-21 7:00 am
What you did with your Pensils with the extra damping is to push them further towards aperiodic. This could be concisely done with even greater impact by optimal internal damping as well as damping the terminus.

This is the same as would be advised to anyone using a current amp to maximally damp down the resonant peak.

dave

Dave,
Can you advice how to damping down the terminus?
Optimal internal damping means more polyfill in the box ??
thanks
kp93300
 
I’d approach damping the Pansil with both more fill, and more startegically placed. For the terminus i would put some thickish open cell foam such that it blocks the terminus and is held in place by the pressure of the well-teased polyfluff.

The PEARL PR-2 was likely one of the most advanced aperiodic boxes ever developed, you can use the pic as a guideline.

103932d1205046585-aperiodic-vents-perkinspr-2-sm-gif


dave
 
I have 12P in superpensil
I have paired with Joe Rasmussen current amp.
The driver donot work well and distorts with moderately heavy bass.
I sealed the outlet with thick sponge used in washing car. The sound is transformed and is quite well balanced. the mid and high frequency are very nice also.
Of late, I discovered that the lunch box amp with TDA 7297 works extremely well in my 200 sq ft room. Bass is even better and more well controlled with excellent pitch of cello bass.

regards
kp93300
It wont work with moderately heavy bass, no matter what sort of enclosure you and me design, as its a fullrange and as the speaker hit bass music excursion, it will produce IMD and compression distortion, and that's why there are crossover,

a FAST build or a 3 way FASTT(subwoofer tweeter) works like Love for markaudio driver.