My Altec A10

**bvn** · February 2nd, 2010, 07:35 AM

Hi, I'm new. I'm a retired (over 10 years) engineer with some audio experience. This is in response to "My Altec A7" - a pretty good thread.
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My front HT speakers are Altec A10's. To be honest, I should call them A9.5's as I had to sell off 4 of the 515's to get them into my house. The A9 & A10 models are the big brothers to the A7 (but, not as big as the A2's).
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I got them from a disbanding Seattle grunge band around 1989. They had repackaged the 800 lb plus, 8' plus theater boxes into something more suited to the road. I repackaged them again into something less that 6' high and about 300 lbs.
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The current configuration is:
291-16A symbiotic driver; 311-90B sectoral horn, and only 2 511B's (like the A9). The smaller packaging has serious impact on the low end. Everything below 130 Hz is routed to the sub-woofer - a modified EV TL440. The cabinet is a 3rd order Chebychev pass band where the half power point is about 30 Hz. It's about 30% bigger and a lot more rigid than the highly compromised EV design the TL440 shares with the TL3512. So much for THX certification. VoTT is, or at least was in 1975, a higher standard than is THX - in my, not so humble, opinion.
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Within my budget limits, I've tried to emulate the Grass Valley / Cinerama electronics. The front end is a Samson S3 processor. Each transducer has it's own amplifier (Samson S170 servo for the 515's and 1/2 of a S120 Servo for the 291). The S3 provides the 500 Hz Linkwitz-Riley, 24 dB/Octave XO, shelving, horn directivity correction, and LF delay. Needless to say, they are extremely clean sounding.
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On the down side, they are more suited to theater use, than as ASRM's (active studio reference monitors). This is especially noticeable when listening to un-processed studio recordings with crashes and hats. So I've doctored them up a bit with a Swans-HiVi RT2H-A (I know, ... Chinese) X0 @ 4 kHz (by the S3) and powered by other half of the S120 Servo. Say what you may, it works.
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The total system uses 17 amplifier / transducer pairs in a THX-EX and ITU surround compliant mid-field configuration. The reference SPL is 126 dB @ +4 dBu. The venue is quite small - 3000 cubic feet with 200 Sabins of adsorption. Normal operation is 50 dB below reference - I still have my hearing

**AltecLansingFan** · February 2nd, 2010, 12:07 PM

Originally Posted by bvn

Hi, I'm new. I'm a retired (over 10 years) engineer with some audio experience. This is in response to "My Altec A7" - a pretty good thread.
---
My front HT speakers are Altec A10's. To be honest, I should call them A9.5's as I had to sell off 4 of the 515's to get them into my house. The A9 & A10 models are the big brothers to the A7 (but, not as big as the A2's).
---
I got them from a disbanding Seattle grunge band around 1989. They had repackaged the 800 lb plus, 8' plus theater boxes into something more suited to the road. I repackaged them again into something less that 6' high and about 300 lbs.
---
The current configuration is:
291-16A symbiotic driver; 311-90B sectoral horn, and only 2 511B's (like the A9). The smaller packaging has serious impact on the low end. Everything below 130 Hz is routed to the sub-woofer - a modified EV TL440. The cabinet is a 3rd order Chebychev pass band where the half power point is about 30 Hz. It's about 30% bigger and a lot more rigid than the highly compromised EV design the TL440 shares with the TL3512. So much for THX certification. VoTT is, or at least was in 1975, a higher standard than is THX - in my, not so humble, opinion.
---
Within my budget limits, I've tried to emulate the Grass Valley / Cinerama electronics. The front end is a Samson S3 processor. Each transducer has it's own amplifier (Samson S170 servo for the 515's and 1/2 of a S120 Servo for the 291). The S3 provides the 500 Hz Linkwitz-Riley, 24 dB/Octave XO, shelving, horn directivity correction, and LF delay. Needless to say, they are extremely clean sounding.
---
On the down side, they are more suited to theater use, than as ASRM's (active studio reference monitors). This is especially noticeable when listening to un-processed studio recordings with crashes and hats. So I've doctored them up a bit with a Swans-HiVi RT2H-A (I know, ... Chinese) X0 @ 4 kHz (by the S3) and powered by other half of the S120 Servo. Say what you may, it works.
---
The total system uses 17 amplifier / transducer pairs in a THX-EX and ITU surround compliant mid-field configuration. The reference SPL is 126 dB @ +4 dBu. The venue is quite small - 3000 cubic feet with 200 Sabins of adsorption. Normal operation is 50 dB below reference - I still have my hearing

Looks to me a very nice, but extremely big system. How big is your listening room?
And how is the sound, is it not very forward sounding?

I also use the 291-16 (with 8 ohm diaphrams) EV HR60 horns and the 416-8B woofers.
The passive crossover I use, is from the model 19, but totally moddified, because I have made a 3-way system of it, the super tweeter I use is a very nice Ribbon Tweeter RAAL 70-10D (from Madisound)
I also use a subwoofer, but everything below 60 Hz is routed to the sub-woofer.
300B amplifier, preamp is a Densen B-200, and my CD player is a modified Playstation PS1

**RonSSS** · February 2nd, 2010, 03:42 PM

Holy cow!
I have a popcorn fart Altec system by comparrison......
ron

**Altec Best** · February 2nd, 2010, 03:43 PM

Originally Posted by bvn

as I had to sell off 4 of the 515's to get them into my house. The

The venue is quite small - 3000 cubic feet with 200 Sabins of adsorption. Normal operation is 50 dB below reference - I still have my hearing

I'm confused is this system for your home or are you using it in a small venue(theater)if it's in your home have you ever tried all aluminium diaghrams for the 291-16 the symbiotic are for higher power handling capabilities(Grunge Band). We Love Pictures here do you have any of your system sounds interesting. By the way:

WELCOME TO THE FORUM !!!!:welcome:

**bvn** · February 3rd, 2010, 05:03 PM

Thanks for the interest. Did I say I was retired (> 12 years)? More time than money!
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Why drop the theater from home theater? Yes, it's in my home - basement actually - where I can avoid ambient light and use affordable projectors. The bulk of my audio experience is commercial. I got hooked in high school (195x), as the geek who helped operate the lighting board, projectors, and sound boards. In college, I was repairing the auditorium's wiring and associated equipment.
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The HT venue is around 400 square feet and is single purpose - by agreement with my very tolerant wife of almost 50 years, my toys do not enter her living room. We reached this accord when she "caught" me repairing a gasoline power mower in our living room. Now, 40 years later, It's my home theater and her living room.
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My true loves are programming computers and brewing bitter ales.
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The bulk of my gear is recycled. Two of my kid's (in their 40's) are musicians. They allow me in their recording studios because I know how to repair things. I also bring beer. My musical proficiency is that I play a mean stereo.
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Re: the Symbiotic 291 drivers. The "Symbiotic" just means that the diaphragm surround is made of Mylar - rather than a crimped up extension of the aluminium radiating surface. Yes, it does mean, more power; but, it also means more graceful ageing - something I've come to appreciate since I've been on Medicare :-) If I blow one out, I will consider replacing as suggested.
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As to the quality of sound. I like my system better than the local IMAX system - which is also THX-EX configured. They have a few more amplifiers and 13 kW of RMS power. Mine is is only 1.5 kW RMS. The big difference is the mono-pole requirement of the ITU surround standard. IMAX is immensely bigger and needs (literally) a sound front. I don't, so each channel is a vertical line radiator. I also have the requirement to listen to my kids recording sessions, so the sound field is SRM equalized (Studio Reference Monitor) which is more brilliant than auditorium systems. Back in the day, we used to roll off the response above a 1 KHz at 3 dB / octave.
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I found this forum because I am about to replace my new receiver for the third time. I am unfamiliar with modern consumer equipment. My previous "audio control system" was a PC with a Creative Audigy2zs and I/O drive. The machine started to fail about a year ago. I replaced it with a $60 Blue-ray, a $200 receiver, and a $200 PC. Much cheaper than building another HT/PC. I connect the receiver, as I did the HT/PC, with "direct injection" - a common studio technique. Everything worked, very well, for 2 weeks, then the left front channel went intermittent. The replacement unit was DOA (left front channel only). The left front channel is an Altec A10 "stack" (as is the right front). So I went poking around the web to see what others were doing with their Altec stacks and consumer equipment. Hi! ya'll
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If you look at Altec blurbs on the A9 & A10 you will notice that they dropped the short horn that is ubiquitous to the A2 and A7 (and those wonderful pictures posted by "old guy"). Horns solve many problems and create a few of their own. Read some early criticisms from Altec regarding Paul Klipsh's designs. The average human ear can easily detect a 3 mSec difference in sound path. This translates into a 3 to 4 foot transducer displacement. Lesser displacements are not so easily identified, but do muddy up the sound - another reason Altec went for the 500 Hz XO. Human ears are more sensitive to higher frequencies. 3 kHz is the worst possible XO frequency. The Altec short horn solved this problem and the modestly improved radiator / air coupling didn't hurt.
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The custom Cinerama electronics provided a better solution. This was commercialized in the Altec 1631A / EV XEQ-2 active crossover. The Samson S3 provides the same solution, but for 2 channels and a 3 way XO at a lower total price.
--- TTFN I'll respond to other concerns later. And thanks for the postings (especially on the A7), they are very informative.

**bvn** · February 3rd, 2010, 06:12 PM

I just re-read this thread. I overlooked a very interesting issue - "forward sounding". Yes the Altec stacks are capable of overpowering everything else. That is what "calibration" is for and THX supplies some very useful standards.
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The center, rear, and lateral speaker systems are Samson 65a SRM's, which by their nature have a lot more presence than the A10's. Bringing this kludge into alignment takes a few hours. My settings and calculations are well documented and easily restored.
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The main saving grace is bass-management. The bulk of the acoustic energy is low frequency. Some say more than 90%. Also, I operate at 50dB below reference (lots of head room). The max SPL from the 65a's is a bit over 115 dB. The HT/PC routed < 128 Hz to the LFE channel and the new receiver uses < 130 Hz. In 6 years of use, I've never needed more than 90 dB from the 65a's to keep up with the A10's.
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My favorite audio test clip comes from "Master and Commander", the first engagement with the French frigate. The sub-woofer may deliver most of the acoustic energy, the A10's may provide most of the acoustic information, but the incidental sounds of grape-shot and shrapnel whizzing around from the surrounds makes my sphincter tighten up. Note: the DTS audio track is noticeably superior to the DD surround track.
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Another useful clip is from Das Boot. The surround sounds of air leaking from the hull is incredible. The room seems to go all cold and clammy.
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Bottom line, Altec stacks can be brought into balance with other, less powerful, speaker systems.
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I guess, this points out another characteristic of the A10's and presumably the A7's. You can hear the difference between DTS and DD. Anybody else notice this?
--- TTFN

**Panomaniac** · February 4th, 2010, 11:19 AM

Great stuff BVN, welcome to the forum. That's a hell of set up you've got going!

DD vs DTS. I've heard the difference in a THX house. When "Titanic" opened I attended the very first showing in Paris, at the the Max Linder cinema. After the show I went up to the booth and had a long chat with the projectionist. We got to talking about sound and he said "Well that was DTS, you want to hear it in Dolby Digital?" I said I did and sat thro the next run.

The DD seemed a bit warmer, but less detailed. The projectionist agreed that had been his finding, too. The DTS was very clean.

About Symbiotic 'frams. I have limited experience, but I don't like them. They sound and measure rough. The aluminum sound much smoother to my ear, and seem to measure smoother, too. That has also been the experience of a number of friends who's ears I trust. I'll soon be swapping the Symbiotic frams in my 291s to aluminum and will post results here.