Alpair 7.3 Heresy

[chrisb]

No doubt the RAAL is a marvelous device, but having heard the 7.3 a fair bit myself, I can't help but think out loud as to why you'd want to cross them over as low as 1800? While they (7.3) can definitely benefit from HP and support woofers, the range from 400-6400 is where I consider these to most particularly excel, and in any case even with an extremely well implemented XO of any alignment, 1800 - 2600 or so would be the range I'd go out of my way to avoid for turnover point - particularly with drivers likely to have substantially different polar radiation patterns in the bracketing octaves.

[markaudio]

Originally Posted by chrisb

No doubt the RAAL is a marvelous device, but having heard the 7.3 a fair bit myself, I can't help but think out loud as to why you'd want to cross them over as low as 1800? While they (7.3) can definitely benefit from HP and support woofers, the range from 400-6400 is where I consider these to most particularly excel, and in any case even with an extremely well implemented XO of any alignment, 1800 - 2600 or so would be the range I'd go out of my way to avoid for turnover point - particularly with drivers likely to have substantially different polar radiation patterns in the bracketing octaves.

Chris's point about crossing-over is important. Low mass full-rangers (assuming the designer's done his/her homework) should be at optimal when used full-range or near full range in an optimsed box. Most of the passive filters I've heard are negatively audible on sensitive cones. Active filtering might possibly offer a better solution.

A note on using large woofs and subs. Most are good for generating pistonic LF frequency but rarely emit the micro-resonances necessary to create discernible music to a descent standard. The large mass of their power-train inhibits and/or prevents micro-resonant emission.

I like to encourage more Diyers to consider designing boxes to get the most out of the single point source full-ranger. My perspective is purist for which I make no apology. Granted Full-Rangers are limited to lower power applications, but we should ask ourselves how much power and consumption do we really need. We humans seem hell-bent on making everything bigger, heavier, being determined to eat up resources and cripple the planet. Yet take a look at Graham's set up in New Zealand, you'll see a pair of Pensil 12's in a massive high ceiling room, easily putting out enough sound to please even those who want laud; All done with 2 Alp12's (stereo), simple box design and a moderate powered tube amp: http://hifi.goneill.co.nz/

Will I make another woofer and tweeter, likely yes but My main focus is that full-range drivers could replace more multiway systems in the future. We owe it to our kids, families, friends and future generations to make better use of resources by trying to do more with less.

Thanks
Mark.

[doorman]

I applaud the effort, research, engineering, and common sense approach of Mr. Fenlon. A superior SD in an optimized enclosure, with a (relatively) low powered (tube) amp is a joy to hear.
My 10.2's in Dave's Mar-ken cabs, driven by 8 wpc. of single-ended power are very satisfying indeed.
Thanks for the ever evolving product line!
Don

[simon dart]

I applaud Mark's sentiment there, but tinkering is personally irresistible on the path to finding my own DIY Nirvana. I originally messed around with adding a second hand homeless tweeter to make my A7.3s more user friendly while I was breaking them in and to try the capacitor-less crossover. I was amazed at how close to greatness the lash-up came.

Since then I have alternated between running the A7.3s with and without the ER4. The ARSXO crossover just provided too little attenuation for the tweeter and it started to show its fundamental resonance quack at moderate volumes, so I now (a little modelling and a lot of tweaking, measuring and listening later), I have a 5KHz 2nd order LR-ish parallel network in place which is putting me on the horns of a dilemma.

The A7.3 naked is remarkable in its resolution but for me it can't quite match the hugely expensive ER4 in the treble where I'm very fussy. But adding the crossover and tweeter does remove a little, and I mean a little: not a lot, of the coherence of the single driver. So as I suspected, there is never a free lunch, but I've had some fun and learned a lot. The real bonus is I now have great sounds in my office while I work.

Which do I think is better? Which will I stick with? I've no idea.

[markaudio]

Originally Posted by simon dart

I applaud Mark's sentiment there, but tinkering is personally irresistible on the path to finding my own DIY Nirvana. I originally messed around with adding a second hand homeless tweeter to make my A7.3s more user friendly while I was breaking them in and to try the capacitor-less crossover. I was amazed at how close to greatness the lash-up came.

Since then I have alternated between running the A7.3s with and without the ER4. The ARSXO crossover just provided too little attenuation for the tweeter and it started to show its fundamental resonance quack at moderate volumes, so I now (a little modelling and a lot of tweaking, measuring and listening later), I have a 5KHz 2nd order LR-ish parallel network in place which is putting me on the horns of a dilemma.

The A7.3 naked is remarkable in its resolution but for me it can't quite match the hugely expensive ER4 in the treble where I'm very fussy. But adding the crossover and tweeter does remove a little, and I mean a little: not a lot, of the coherence of the single driver. So as I suspected, there is never a free lunch, but I've had some fun and learned a lot. The real bonus is I now have great sounds in my office while I work.

Which do I think is better? Which will I stick with? I've no idea.

Hello Simon,
Glad your experimenting. I've found a little time to look at this thread (not as much as I'd like). Bear in mind I'm less than a stone's throw from several ribbon makers (I have some on my bench), be aware for allot of tweets, its a fine-line between "actual sound" reproduction and distortion in the ranges you describe.

I wouldn't normally recommend any audiophile to add a tweet (of any type) to a driver the likes of Alpair 7 Gen.3. Given its wide range (close to 30-kHz) and dispersion, in a good box mated to a descent amp and accurate source, the Alps will emit near faithful reproduction to the original source.

Aging engineers like Me, Ted Jordan et.al increasingly lament the gradual dumbing down of "High Fidelity" (being acoustically faithful to the original source). 2 way and multi-way systems, while can be good, split the emitted range and with phase differentials, create an "artificial" sound. Since these systems have been dominant in the market place for so many years, we've become assimilated to their output. This doesn't mean all split systems are bad. Indeed, I have a fondness for Victor SX 500 Spirits as I own 2 pairs in mint condition that do a nice job:

VICTOR ƒXƒs�[ƒJ�[ƒVƒXƒeƒ€SX-500‚ÌŽd—l ƒrƒNƒ^�[

I encourage most experimentation. Indeed, its why I made the effort with the CHP's and CHBW's because I appreciate that not everyone is "purist". Colin's forthcoming Rossendales project with CHBW's and a ribbon should be very interesting:

4 x CHBW + RBT95SQ Ribbon Tweeter

Summarising, your idea of adding a tweet is based on personal taste that I suspect has been influenced by the audio market over the years. That doesn't mean its a mistake, but we all should be aware of system design limitations and those influences that bear down on driver/system design. For those who wish to remain purist, keep the system simple.

I'll continue doing my best to remain within the bounds of original High-Fidelity, while trying to accommodate Diyer's desires.

Cheers
Mark

[ultrakaz]

How about taking the AR cross schema and applying the highpass to the A7.3 instead and using some wide bandwidth woofer? One could tweak the values so that you are crossing around 250Hz or so and thus relieving the A7.3 from the heavy lifting, albeit at 1st order slopes. I've high passed a few "full rangers" before and all have improved mids and highs.

[planet10]

Originally Posted by ultrakaz

How about taking the AR cross schema and applying the highpass to the A7.3 instead and using some wide bandwidth woofer?

AR XO is a specific instance of a series XO. One would be ahead just starting from scratch.

dave

[wallacefl]

Originally Posted by chrisb

No doubt the RAAL is a marvelous device, but having heard the 7.3 a fair bit myself, I can't help but think out loud as to why you'd want to cross them over as low as 1800? While they (7.3) can definitely benefit from HP and support woofers, the range from 400-6400 is where I consider these to most particularly excel, and in any case even with an extremely well implemented XO of any alignment, 1800 - 2600 or so would be the range I'd go out of my way to avoid for turnover point - particularly with drivers likely to have substantially different polar radiation patterns in the bracketing octaves.

The problem with using the OEM Raal 20xr is that the crossover is sort of designed into the driver and I have no idea of how to get around this. What I would really like to do is use it LR 12db cut at about 7000hz but I do not have measuring equipment/etc so I am open for any suggestions. Thanks