Mark's new Alpair 7

[hayenc]

I will write more in the Goldwood H-frame thread, but I have been running a pair of Alpair 7's for the last couple of days in an open baffle on top of a Alpha 15a H-frames. Rolled off below 200 hz to match the Alphas, especially during break-in, but here are first impressions:

Somewhat more detailed than the Jordan. Highs equivalent to the Griffin Jordan/AC ribbon setup. I have not hooked up a FS 125, but the WR125 with tweeter is not as detailed, but maybe a bit more efficient.

One of the most impressive speakers I have seen for the money, although I have not tried any Fostex (especially at an equivalent price!). The real surprise is running it against a pair of Alpair 12's, also in an OB. The 7's seem to be more detailed and have not been able to get quite the same stage with the 12's, although the 12 have more richness and almost creamy texture to them, especially with female voices like Norah Jones, Eva Cassidy and Holly Cole. May need some high end compensation on the 12's. Whoever thought one would say that about an 8" full range.

Still undecided as to which to settle on. Will take them both the the Arizona DIY get together next weekend and will surely have more opinions from that.

[c2cthomas]

I'm look'n forward to following this!! Would luv ta see sum photo's.

[markaudio]

Originally Posted by mashaffer

Mark;

I have just begun to look at some of your drivers for a mini-console luggable project I am working on. They look rather nice (haven't run numbers yet but look doable). One concern I have is durability of the light weight materials in the hands of a teenager. Have you found these driver to be pretty rugged.

mike

Hi Mike,
Ummmmph - teenager! If teenager likes to poke the cones with fingers, that' a problem but seriously, I don't know of any full range driver that can handle loads of power (teenager's desire for maxed out volume?). You'll have to tell me more about what you're trying to achieve.

Mark.

[mashaffer]

Thanks Mark. This project is a graduation present for my step daughter. The concept is a mini-console setup for iPod and other line level devices. If you picture Dad's old stereo console shrunk to maybe 2 or three feet long that is pretty much the idea. I want to maximize audio quality such as detail, imaging, smooth response etc while still having enough guts to "rock" a bit for small to medium rooms.

I realize that in this size category I am not going to get realistic organ bass but again trying to maximize performance within this size category. So my approach to this is to use full range drivers at least above 200Hz driven by SE tube amplifier to give the clarity free from crossover mush (my own experience with wide range drivers has been extrememly positive). The bottom end would be filled in by SS powered subwoofer(s). Again given size limitations I am not looking to get much below 40Hz here.

My initial thought was to try for FR drivers that could get down to about 80Hz or so in order to allow the use of a single sub without sacrificing imaging. Initial looks indicate that your 6" or the Jordan might be capable of this but it still puts a lot of demand on the FR's. With that in mind I am considering using 6 1/2" (or so) subs below each FR so that the mains can be crossed at 150 to 200 Hz to ease their job and protect them from over excursion. If I do that then even open back is an option for the mains.

My initial concept was for something on the order of the RH-84 SEP EL84 amp with a few twists thrown in for the mains but I am not averse to going with a 6L6 or EL34 based design if necessary to achieve adequate output. The plan for the sub(s) is to use a commercial sub amp or separate modules with my own active crossover.

Too much information?

mike

[markaudio]

Hi Mike,
Nice idea for your daughter's graduation. I'm tempted to suggest the new CHR-70 but before I say more, are you going to consider the look of the design? I'm guessing your daughter is into fashion, looks and style?

Thanks

Mark.

[mashaffer]

She likes antiques.

mke

[planet10]

Originally Posted by markaudio

I'm tempted to suggest the new CHR-70 but before I say more, are you going to consider the look of the design?

My thot was to the EL70. Patially due to the higher efficiency. Partially due to how much i'm enjoying the EL70eN in the new box. Partially due to a gut feeling they would be more robust.

I do suspect A7 will have more finese thou.

dave

[mashaffer]

Found the TS params for the EL in another thread. Looks very promising! A couple of dB more efficiency is good in this application. If they are indeed sturdier that is a bonus. I will need to get some 4 ohm trannies for testing but that is not a problem.

mike

[planet10]

Mike,

Reminds me i have probably been running the new speakers on the 8 ohm taps... let's see if they get better. Grey Cup 1st thou.

dave

[Scottmoose]

A few general A7 thoughts...

A lot of what I said about the A12 in terms of initial impressions also applies to the A7 (albeit on a smaller scale), so just insert A7 for A12 in the ponderings below:

Physically the A[7] is impressive when you get your hands on a pair. It's a very pretty driver (as far as such things can be...). They're weighty [for their size], and the build quality is excellent; the basket is the best example of the MA composite frame I've seen yet. Feels very solid, and the screw-holes are centered on the basket, rather than being toward the outboard edge, which is useful. Where they really score is when you start looking at the finer details. The cone is quite remarkable; extremely thin / light, beautifully [multi]formed / pressed, and the glue-line of the dust-cap to the main cone is as tight as I've seen; Mark's production tolerances are very good through necessity. If they weren't, this thing wouldn't work. The suspension is also beautifully done. The ribs of the spider are of varying diameter, while the front suspension is extremely supple. Right on the edge I'd say. Connectors are solid & colour coded for ease of use; you'd have to try very hard to damage them.

In spec. terms they seem reasonably flexible; plenty of options for BR, sealed, QW, BLHs etc. & a low mass-corner. Mark's usual, semi-BBC response shaping makes them an easy listen for extended periods, although given their fairly extreme upper extension for a driver of this kind (half an octave above the nominal HF audibility threshold) probably not a good idea to give them a bright source or amplifier, especially if your HF hearing is still decent.

Detail is exceptional, pretty much as good as the current Alpair 6. It doesn't quite have the latter's delightful shimmer through the midband, but being a little larger, it doesn't run out of steam as quickly, & the powertrain (I like Mark's description & decided to use it in conversation more often) seems more stable -it remains consistant even when pushed to the outer edges of it's operating envelope where the A6, pushed near it's own limits, can start to loose a little control in the upper mids. I surmise that's largely due to the new suspension. Basically, it sounds like a 0.35 scale A12, with the obvious gains (fine detail) and drawbacks (less efficiency & dynamic headroom) you get from such shrinkages. It's another cracking driver, especially for modest-sized rooms & SPLs, and for material like folk, blues, small-ensembles etc.