Altec Valencia = Heathkit AS-101

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I've actually seen three sets of these on CL in the last 6 months ranging from an asking price of $800 - $1,200. I usually e-mail the seller and state if they don't get their price, to let me know and I would make an offer. I never snatched any of them up (though seriously considered it) because if I get a set of Altecs, they will either be 604s, or have an 802 or maybe 808 driver. The Heathkits got the Altec equivelent of the LE175 as opposed to the LE85 drivers.

BTW, I absolutely LOVE the pale green of the Heathkit equipment. :hug:
 
They had a day to temperature stabilize after 2 days in the cold truck and I don't know how long in the Storage warehouse ...

Have to move the Model 15 cabinets out and get these separated further - but - not bad at all.
Touched up some nicks with furniture stcks and wiped the tops with orange oil, then spent about 40 minutes listening to all kinds of music
No superlows and no high-highs - kinda what I expected considering the era -
I think I mentioned that I had a demo of a well modded pair Jan 6, with slot-tweeters on top, and they were amazing - crisp and dynamic,
and his DID play lows and highs! He's eager to help me with these, so I plan to redo the crossovers and do some mods to sweeten them!

Heaths_5862-adj.jpg
 
If you put the stock AS-101 diaphragms in your 908 driver bodies............................................

You would gain:

5-6db in sensitivity.

More than an octave in natural HF extension.

Enough sensitivity headroom to use an EQ;d and compensated network like the Z-19 or N-1201/model 19.

No permanent or irreversible modifications needed, you can even bolt the 806 covers to the 908 bodies such that you don't have to mess with the wire terminal changes.

With the heavy, klunky symbiotik diaphragms in them, i absolutely promise you have not heard close to what the ferrite 900 series driver is capable of in the upper octaves.

The symbiotik is flawed for use as a stand alone HF hifi driver. The diaphragm is heavily compromised giving up extension and smoothness for ruggedness and power handling.

Just some food for thought.
 
Sadly, I don't OWN any 908 drivers, I sold the Model 15 parts to fund buying these (and appease the wife).

But tell me about the change - why does this work - just better magnets and motors?
 
The design change from the 800 series alnico drivers to the 900 series ferrite drivers resulted in an upward frequency response shift of a full octave or so.

I'm not an engineer or even formal expert. But, i believe you can attribute the shift in response to both higher magnetic strength in the gap, as well as the reduced internal volume of the cavity behind the magnetic gap. The alnico drivers, particularly the 802/808 body has comparatively large cavity behind the voice coil gap. This certainly has to affect both the resonant frequency, and acoustic loading of the diaphragm.

Understanding the differences between the symbiotik diaphragms(left), and the tangential surround all aluminum diaphragms(right) will also be helpful.

Sym%2B%252B%2BAlum.jpg


The symbiotik diaphragm has a thicker/heavier dome, a heavy voice coil, and a good sized bead of adhesive connecting it to the kapton surround. When these diaphragms were installed in drivers at the factory, part of the QC process included driving them with a 500hz sine wave at 30 watts. If it "clacked"(diaphragm physically contacts phase plug) they would install the required thickness paper shim between the mounting hub and front plate such that the diaphragm would no longer contact the phase plug. They were designed exclusively with the pro-sound market in mind.

All that said, they can make very good midrange in a 3-way system. If the klipsch crowd ever discovers what they can do to improve heritage models, the market for them will explode.

The tangential aluminum "hifi" phragms were produced in an array of versions. Is best to generalize on them since there is scarce info ever published, and since they're all NLA except in the questionable used market, the variations are worthy of discussion in a separate/dedicated thread. These diaphragms are much lighter in the moving assembly than the symbiotik, and went through a number of revisions and refinements to result in the best overall balance of performance and reliability.

The only options available new today are the 34647(8ohm) and 34852(16ohm) phragms from GPA. They are made on the same tooling, from the same materials, to the same specs as they were on the Altec factory floor.
 
Hmm - here is an inside view of the 908-8As I got from bartertown -
I was told they were modified to be like the 902s. I gather the thick felt in the cap is one such mod.

ALTEC-908-8A_4734 2.JPG ALTEC-908-8A_4788.JPG
 
Yes, the felt damper is part of the change. The stock 908 would have also had a loading cap installed on top of the diaphragm, another part of the conversion is sourcing shorter screws and omitting the loading cap. The diaphragms are the 3rd and probably most differentiating part of a conversion, IMO&E.

Use the following only for it's photographic content, it's exactly how a stock 908 would appear inside the cover.

The 902 "T" that it specifically references was a last ditch effort in attempt to get some reliability at lower than 1200hz XO points with the more delicate all aluminum tangential surround diaphragm.

902t.jpg
 
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Hi Heather, those 908's have the Symbiotik diaphragms in them. They came with them. The 902's have the aluminum diaphragms.
When I got my 908's they had both the Symbiotik diaphragms and the black plastic loading caps. I purchased the newer aluminum diaphragms and the rear covers with the felt from GPA and discarded the loading caps. The screws holding the diaphragms must be changed out to shorter ones as well.
Just a FYI, the 908/902 drivers with the 3/4 aluminum adapters I machined fit into the HeathKit cabinets, I just pulled a bit of the insulation off of the rear panel.
I think the new 902 drivers that GPA sell's have an 1" outlet so no adapter is needed.
So bone stock, what do you think of them?

BillWojo
 
Hi Heather, those 908's have the Symbiotik diaphragms in them. They came with them. The 902's have the aluminum diaphragms.
When I got my 908's they had both the Symbiotik diaphragms and the black plastic loading caps. I purchased the newer aluminum diaphragms and the rear covers with the felt from GPA and discarded the loading caps. The screws holding the diaphragms must be changed out to shorter ones as well.
Just a FYI, the 908/902 drivers with the 3/4 aluminum adapters I machined fit into the HeathKit cabinets, I just pulled a bit of the insulation off of the rear panel.
I think the new 902 drivers that GPA sell's have an 1" outlet so no adapter is needed.
So bone stock, what do you think of them?

BillWojo
Its interesting. The drivers are all marked 8 ohms in the Heath AS-101 cabinets - but they have no ports, so they seem more like Valencia 246A cabinets.
So - Bone stock?
Seems I gave up some lows under 100Hz that I had with the JBL 2214H woofer in the Model 15 cabinets ... (nothing like a 2214H!)
I'm thinking that stuffing the lower part of the AS-101 cabinet with polyfill might help.
I'm also thinking I have some high-end loss in the "Valencias" - but hoping a crossover redesign/refurb will help with that.
I mean, the stock caps (and design) are 50+ yo ... can't hurt to rework them -
(I have no plans to biamp them - I don't want that complication in my simpler system.)
 
I mean, the stock caps (and design) are 50+ yo ... can't hurt to rework them -
.................. and those were not the best caps to begin with. Just some Dayton 5% polys would almost surely clean things up a good deal. Those stock Heath caps can get real leaky(DC leakage) and that lets dirty bits of signal through that a healthy cap filters out.

You might also experiment with a bypass cap around the L-pad if you seek to further brighten the upper end.
 
The polyfill is an interesting change. I had 2 old "plush" sofa pillows we have not used in ages, and found a roll of fiberglass window screening material.
So, I cut the window screen in half, and laid it across the woofer, tucking it under the accoustic batting on the left right and bottom of the baffle board.
That is to keep filler from getting anywhere inside the woofer frame and up against the back of the cone.
I then cut open a pillow into each cabinet, shaking the polyfill out, and fluffed it around the woofer section of the cabinet.
Polyfill is to seemingly enlarge the size of a cabinet - and since folks have said Valencia cabinets are too small for the woofer ... Its an easy test.
I then closed up each cabinet, and stood them up where they have been all along. Same amp, etc.

I put on The Art of Noise - "The Seduction of Claude Debussy' - Dreaming in Color.
Its a track that hits a low note and slides lower. Its not super low, Boz Scaggs Dig has lower notes, but I played the song yesterday, and know it.

When I played "Dreaming in Color" yesterday, there was almost nothing on the bottom.
But just a few minutes ago - I heard the initial note and a good part of the slide down. I've heard it better, but it really DID help.

I played Boz Scaggs - "Dig" - Thanks to You. (An album we all know from Zilch, and a song they played in the Harman Demo truck a few years ago).
I can tell its now fuller on the bottom as well ...

I know - this is all "quick and dirty" - some of you are saying "no empirical data - c'mon Heather ..."
Bad me - I did not think to run the Octave RTA on Emma's iPad so I have no baseline "before" image,
but I know the songs, I kno how it sounded yesterday, and know its going lower now.
So - one easy improvement!

Okay - here is an After screencap using the "Delos Demo CD" - Stereo Pink Noise signal -
Only mod I've done was adding polyfill ... (much work left to do!)

Hopefully I can bring up the highs when I redo the crossovers ...

AS101-polyfill_5883.jpg
 
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I would try to put a 2 mfd cap between + input and + terminal to the horn. With the 8 ohm load, this will provide a "boost" to those frequencies above 10kHz. If you find this is too bright, try putting a resistor in series with the cap. The value of the resistor affects the crossover's "knee-point" such that adding 4 ohms reduces this frequency to ~6,500 Hz, which still plenty high for the "boost" for your application.
 
I have a full set of AS101 components, including crossovers, which need overhaul; I also picked up a pair of EV solid mahogany cabinets that are 36" tall by about 22" wide and 17" or 18" deep--more volume than the original cabs, which were trashed. I'll set the horn on top of the cabinet and plan to use slots similar to an Onken design either on the sides or top and bottom. I'm still not sure how deep to make the slot, it may take some experimentation. I'm hoping they'll rival my 846a Vals; we'll see.
 
I have a full set of AS101 components, including crossovers, which need overhaul; I also picked up a pair of EV solid mahogany cabinets that are 36" tall by about 22" wide and 17" or 18" deep--more volume than the original cabs, which were trashed. I'll set the horn on top of the cabinet and plan to use slots similar to an Onken design either on the sides or top and bottom. I'm still not sure how deep to make the slot, it may take some experimentation. I'm hoping they'll rival my 846a Vals; we'll see.

Very cool - larger cabinets should help these parts play better (which were also used in the A7 VOTT cabinets)
You should def start a thread and keep us informed of your progress - those EV cabinet should be gorgeous!

Altec Lansing 1965 Advertisement.jpg
 
Time for some Horn Damping! The Heath AS-101 have Altec 811-B horns - and metal horns are legendary for ringing.
I hadn't heard any problems in my 2 months of auditions, but I don't play loud - and it seems reasonable to anticipate such problems -
I've certainly seen enough threads where others have mentioned such problems.

My guru had mentioned a material called Q-pad - its a self adhesive sheet product used in car soundproofing.
I mentioned dynamat - something my car audio buddies talked about - he replied:
"NOPE! Dynamats will not get the job done. Q-Pads are a lead-impregnated composite sheets. Dynamats and Q-pads are not the same."

Amazon sells small packs of 6 12" x 12" sheets for about $30 - got some about 2 weeks back.
This is apparently a fiberglass product - sheeting within the tar -
But if it damps it, its certainly a cheap enough process.

So I lad the cabinets down on their face, pulled the back, used a small 1/4 drive ratchet and pulled 2 bolts from the upper flange
holding the horn to the cabinet, and then 1 nut holding the driver and horn to a metal bracket, and pulled the horn.

Its very clean - but I wiped down with alcohol, just to be sure. I figured 1 1/2 sheets of Q-pad would probably do each horn,
so I did some measurements, cut one sheet in half, and trimmed the edges so it would fit the large sides of the horn.
The flanges taper to the main horn body - and are 1.75" at the deepest, so I cut a piece from another sheet, trimmed it to fit the taper,
and used that as a template to make 3 more on that sheet of Q-pad. The material is self sticky, so I peeled off the backing and slipped it into place.
On a hunch, I took the pieces I cut off when I shaped it and used them on the narrow side of the horns - I mean, why not use all the material?

After it was done I took it upstairs, fired up my blow (hair) dryer, and heated the pad up, just to bond it even tighter to the horn.

So, here is the 1 I've done - I'll do the other after dinner or tomorrow. [Its dinner time]

I have some tips for damping the vertical blades on the front - more about that next time!

811B_6402.jpg 811B-Qpad_6401.jpg 811B-Qpad_6400.jpg
 
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I haven't done anything to my horns yet. I have read the complaints about horn "honking" but never experienced it despite the fact that sometimes I play them loud. I often wonder if it's something upstream feeding the horns that isn't quite right. Horns need very little signal strength to play loud and maybe it's a distorted signal causing the honking? Or maybe my ears just don't hear it. Some folks do hear and complain about it and some folks don't.

BillWojo
 
I agree - I never heard "honking" or ringing in this system, but I can hear a ring when I wack the
unmounted metal horn with a screwdriver handle.
Its easy enough to treat while its apart, and $36 (shipped) is cheap enough to not be a worry.

I sent pictures to my guru - he replied and said to apply a second layer over what I just did ...
Fortunately, I have enough sheets in the box to do that.

Like the ceramic tiles and granite tile layers on the cabinet outsides,
or shorting caps on unused inputs, each step adds a degree of improvements,
and the cumulative effect of these techniques on his AS-101 I heard in January were just stunning!
 
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I agree - I never heard "honking" or ringing in this system, but I can hear a ring when I wack the metal horn with a screwdriver handle.
Its easy enough to treat while its apart, and $36 (shipped) is cheap enough to not be a worry.

I sent pictures to my guru - he replied and said to apply a second layer over what I just did ...
I have enough sheets in the box to do that.


Like the ceramic tiles and granite tile layers on the cabinet outsides,
or shorting caps on unused inputs, each step adds a degree of improvements,
and the cumulative effect of these techniques on the AS-101 I heard in January were just stunning!

You may or may not have answered my question, but I am happy that you posted what you did regarding the 811B horns. As you may recall, like you, I am also a long time JBL fan due to their realistically "live" qualities. I have much more recently been intrigued by Altec, to the point that I pave purchased, among other items, 811B horns. Though I read frequently of the necessity of damping the horns, I notice that many people do not, feeling that it is not required. Additionally, I was concerned that damping the horns might actually reduce the degree of very "live" qualities that these horns inherently possess. Is this at all a legitimate concern? Thank you.
 
Next step - short piece of 5/16 wood dowel with RTV silicone at each end to deaden any buzzing of the blades

Horn-blades-dowel_6405.jpg
 
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