Running an A7.3 at full power

[Vix]

Bob, I like your idea. But instead of going with a delicate A7.3 why not go with EL70? Maybe not as refined but more robust. If one is not enough, use two EL70! By the way, what about bass drivers? Do you plan to make a sort of transmission line, or just a plain BR?
Regards
Vix

[Bob Brines]

The EL70 is out of print with a questionable supply future. Not the best choice for one who hopes to sell a few speakers. I went though that when Fostex pulled the AV line.

My speakers are designed for jazz, girl-and-a guitar and pre-1800 classical. Delicacy is the name of the game. But that includes a lot of double bass and
16' organ. So--firm bass, delicate top. Otherwise I might as well to a conventional 3-way with all of its attendant baggage.

Bob

[Swifty]

Hi Bob,

The Alpair 7.3 is a perfect candidate for the intended purpose in my experience.

I'm running the Alpair 7.3 in a FAST configuration with a 10" subwoofer, the Seas L26ROY. You can find the details of the build here in the Markaudio forum. I'm crossing them at 200hz RL4 with DSP. The system is very dynamic, and surprisingly, the two drivers blend incredibly well. The loudspeakers are bi-amped with 2 100w@ 4 ohm class d ucd amps (Hypex As2.100 units with dsp). Last weekend we had a get together of a Dutch audio forum, and I brought these loudspeakers to the venue, The consensus was it outclassed a RAAL tweeter/Audio Technology Flex Unit Mids/Flex Units Corner Subs system in the same room.(

One of the recordings I demoed was "Dances Of The Opera" By the Minnessota Orchestra directed by Eiji Oue. It does not get much more dynamic than that. Even on very high levels (0db on the dsp) the Alpair sounded completely at ease.

I would not use the Alpair 7.3 at those levels for Rock music, where the average SPL is much higher for much longer time periods, but who would listen to that kind of music at those levels anyway? Not me...

Using the 10.2 in a Fast config would rob the 10.2 of its main strength (the bass region) while under utilising the potential of a FAST system (great bass extention AND great treble/better dispersion) imho.

[Rullknufs]

Originally Posted by Swifty

One of the recordings I demoed was "Dances Of The Opera" By the Minnessota Orchestra directed by Eiji Oue. It does not get much more dynamic than that. Even on very high levels (0db on the dsp) the Alpair sounded completely at ease.

Great album but I think the track Stimela with Hugh Masekela has more dynamics and is more interesting to listen to Try playing this song at reference-level and your speakers will most likely be sweating quite a bit

[planet10]

Bob, if i may ask, what 8"? i'm still on the hunt for an SDX7 replacement.

dave

[markaudio]

Originally Posted by Bob Brines

I am looking at a FAST speaker on steroids.

First, I personally, and most of my customers use an average listening level of 70-75dB, which is going to equate to ~80dB/w/m. While very little is the jazz/easy listening genre has anywhere near 15dB dynamic range, classical music can easily have a 30dB dynamic range. So, it's a matter of headroom.

Second, the bass produced by a large driver feels different from the bass produced by a small driver. I found this out in spades while playing with an 18" h-frame. Therefore, I chose a pair of 8" for the bass. This will provides an Sd of nearly a 12" driver but allows a cabinet width on less than 12". The two 8's will provide 105dB in room at 40Hz. That should be enough to start rearranging the furniture.

I would like to use the A7.3 rather than the A10.2 because it sounds better to me in the treble. Perhaps I need to rethink and go with the A10.2 as it is slightly more efficient and probably more robust.

Bob

Hi Bob, Guys,
Ummmmmmmph.............

Interesting thinking and makes for a very interesting set of technical scenarios. Let me think how to discuss the situation. I'll need a bit of time as I'm moving offices and homes (nightmare) and my lower back is killing me with constant pain.

But briefly, "Headroom" (dynamic or otherwise), in terms of what is actually happening to a drivers power-train in terms of oscillatory, transition and resonance, is often mis-understood.

A power-train under varying load conditions is a very complex animal, and extremely complex animal. "Headroom" is far too broad, loose and non-complex term that design engineers in most other industries wouldn't give it time of day.

I need time to think how to help better illustrate the relationship(s) between power and emittance.

Sorry Bob, this doesn't help you immediately, but simply building bigger isn't an automatic guarantee that greater "headroom", such as it is, gets bigger. Its never that simple (wish it were).

Anyone wishing to hear what a driver should do (can do) with classical crescendo, consider (or do) the following:
1 - Treat yourself to a pair of Alp 12P's
2 - Build a pensil 12.2 (or one of Bob's potential future box designs) and tune to taste.
3 - Warm up a nice little tube amp
4 - Find and buy this CD (see pics): Seiji Ozawa San conducting the Saito Kinen orchestra,(Decca)
5 - Select "Un Bal", the 2nd movement.
6 - Open your best bottle of wine or beer, kick the kids, dogs and any other distractions (nicely) out the room and press the play button.

Trust me, you'll have quite a long think (re think) about headroom.

Cheers
Mark.

[markaudio]

Hi Guys,
Broadening Bob's point about power/headroom, he mentioned his customers wanting systems that "re-arrange the furniture", this potentially opens up a complex debates about:

1 - The authenticity of musical output in such load conditions and the lack of High Fidelity (original meaning).

2 - The role that Full-Range drivers can play in such systems and how best to deploy them.

The first issue is the choice between High Fidelity and "acoustic effect".

I'm happy to spilt this thread should the discussion broaden, so Bob's practical requests won't get overwhelmed.

Cheers
Mark.

[buzzforb]

Originally Posted by Bob Brines

I am looking at a FAST speaker on steroids.

First, I personally, and most of my customers use an average listening level of 70-75dB, which is going to equate to ~80dB/w/m. While very little is the jazz/easy listening genre has anywhere near 15dB dynamic range, classical music can easily have a 30dB dynamic range. So, it's a matter of headroom.

Second, the bass produced by a large driver feels different from the bass produced by a small driver. I found this out in spades while playing with an 18" h-frame. Therefore, I chose a pair of 8" for the bass. This will provides an Sd of nearly a 12" driver but allows a cabinet width on less than 12". The two 8's will provide 105dB in room at 40Hz. That should be enough to start rearranging the furniture.

I would like to use the A7.3 rather than the A10.2 because it sounds better to me in the treble. Perhaps I need to rethink and go with the A10.2 as it is slightly more efficient and probably more robust.

Bob

Bob, I couldnt agree more with your assesment of the 7.3. IT has a clarity that I truly enjoy and miss when I am listening to something else. The 10.2 just does not cut it in this regards. On the other hand, the 10.2 has a very smooth and pleasing musical nature. On simple jazz numbers, I think it beats the 7.3, but the second the music gets dense, things change quickly in favor of the 7.3. I have not yet tried the 10.2 with a sub, but adding a sub to the 7.3 at about 350-400 range, adds body while retaining the detail that makes it special. I have even considered the 10.2 for use from 100-400 and 7.3 at 400 and above. Both supported by a quality sub down low. Heresy, I know. Main concern for me is FR handling most of the reproduction with difficult decision involving what to do to add body. It really is true that in everything you have a trade off.

[Bob Brines]

Originally Posted by planet10

Bob, if i may ask, what 8"? i'm still on the hunt for an SDX7 replacement.

dave

I'm looking at the Dayton Audio RS225-4, two in series for an 8Ω load or Dayton Audio RS225-8, two in parallel for a 4Ω load. Most likely the latter as I will be powering the bottom with a T-amp.

Bob

[Bob Brines]

buzzforb,

I am inclined to agree with you on the A7.3. I have used the A10.2, and it is a very smooth and satisfying driver, but when you start playing gut-strung violins, harpsichords and lutes, the A7.3 wins hand down. On the other hand, the A10.2 offers a real single driver solution from the mid 30's up.

Bob