Hello,
I joined this forum today after one of your members recommended it. I've been browsing it and it seems the members here really know their classic Altecs. I just bought a pair of Heathkit/Altecs AS-101 speakers in near mint condition from a local classified ad (Altec drivers are mint--cabinet near mint). I'm a long time Altec user--I have a pair of P.A. Voice of the Theater A7 speakers that I use for P.A. with my (rock) band (bought them used over 10 years ago). I also have a pair of Altec Valencia speakers that I use for my "downstairs/basement" home stereo together with a pair of altec model nine speakers (4 speakers sound better than 2!). The AS-101s that I just bought are for my "upstairs" (living room) stereo. I've been looking at the altec library and the AS-101s are most similar to the altec flamenco speakers from 1971 -- identical drivers and cabinet other than the grill. Their cabinet is a little different from the Valencias.--same drivers as the valencias and the A7 voice of the theater. Anyways, I opened them up and took some photos of the drivers, etc. and I have a few questions. I noticed the caps look really bad in the crossovers--there are three caps per speaker (six total) and a couple of them look like they may have leaked oil at one time.I'd like to replace them but I can't find the right value caps. The three that are in there say 8 mfd 50 vdc, 10 mfd 50 vdc, and 11 mfd 50 vdc. The closest I've found are Solen caps at 8.2 uf 400vdc, 10 uf 400 vdc, 12 uf 400 vdc. The original caps say "chicago condensor corp" +/- 10% and the Solen caps are rated at +/- 5%..... QUESTION ONE--Do you think the Solens would be close enough and would result in cleaner crisper sound? Right now one horn seems to be slightly brighter than the other. QUESTION TWO--could that be caused by a bad cap(s)? The woofers and horns both say made for Heathkit by Altec Lansing and have Heathkit part numbers on them. I also noticed there's a number stamped on the outside of the diaphragm for each horn. QUESTION THREE Is this a batch number (GPA didn't think it was a part number they had never heard of it?)
One of the horns (in the photo) has 391133 stamped on it and the other one has 391124 stamped on it--are these just different batch numbers or am I dealing with two entirely different diaphragms (QUESTION 4?)? Both 806A horns (heathkit/Altec) have an Altec stamp on the side which seems undisturbed/unmoved which makes it look like they've never been opened (and makes me think the diaphragms are the original altecs from the 70's)--is this a correct assumption (QUESTION 5)? see photo...
I was surprised that even though the Heathkit Altecs have the same drivers as my Valencias, the Heathkits have a SLIGHTLY better sound (warmer/fuller) other than the fact that one horn seems very slightly brighter than the other.....
left to right--Altec Valencia with model nine on top, heathkit AS-101 (voice of the theater in heathkit cabinet).... Here's the inside of one of the Heathkit As-101 (they look identical inside).
Anyways, I would really appreciate anyone who could answer some of these questions for me--it's not easy to find accurate info on vintage Altecs....
Thanks,
Dave
The 391 numbers are date codes...391 is Altec's EIA number, next number is last digit of year made, probly 1971.
As far as caps- 5% are higher quality, no sweat. That is tolerance, ie how far they can be off and still pass QC.
Check Martin Pro Sound and Parts Express for caps. Both carry a good selection.
I like 100 volt caps for home use, opinions may vary.
Edit- just noticed the 5-71 on the caps, certainly implies 1971 to me....
Your neighbors called. They like your music.
Thanks--I had no idea how to "date" my speakers. I guess that means my Valencia speakers are from 1969 since their horns/diaphragms are stamped 391943 and I'm pretty sure they weren't still making Valencias in 1979. I've been told that the vdc rating on caps is how much power it can withstand and that what I'm really trying to match is the uf figure. So, I'm assuming 8.2 uf is close enough to the original 8 cap, Solen makes a 10 uf cap which matches the original 10, but is a 12 uf Solen 400vdc going to be close enough to the original 11uf 50 vdc (keeping in mind the Solen is +/- 5% and the original is +/- 10%)? So I guess there's two questions there. Is 400 vdc fine to replace 50 vdc caps and is 12 uf close enough to the original 11 uf (400 vdc are the lowest I've found in most brands of caps)... I've read that it's good to have 400 vdc in crossovers--all it does is give you more headroom and shouldn't effect the sound otherwise--do you think that's true? Could a bad cap(s) be the reason one of my horns sounds doesn't sound quite as bright as the other? I read somewhere that it's always a good idea to replace the crossover caps on a 40 year old speaker--is that usually true? Lastly, the "copper" doesn't look that great in these crossovers either---is that something to worry about or should I wait until after the caps have been replaced and then see how they sound before I worry about the "copper".....I think I'll need to start a new thread just on crossovers.....
I think you'll find the 10uF and 11uF caps are parallel in circuit, just replace them with a single 21uF Solen.
I'd also recommend replacing the L-pads at the same time.
Not all vegetables make good leaders.
At the risk of sounding (even more) ignorant--the L Pads the "tone control pot." on the back panel of the speaker, right? I leave them turned all the way up and I've moved them around and there's no static/noise when I move the knobs--could they be causing one horn to be not quite as bright as the other even though I leave them all the way up and they're not noisey when rotated? At parts express I see a few L Pads all rated at 8 ohms. The 806A Horn and 416Z Woofer in my Valencias both say 16 ohms on them -- is the Valencia an 8 ohm speaker? The Heathkit/Altec AS 101 has the same drivers as the Valencias except they have 8 ohm printed on them and also have printed on them "manufactured for Heathkit by Altec Lansing". Are the AS-101's 8 ohm speakers--can I use 8 ohm L pads for both the AS-101s and the Valencias? Also, I checked parts express and they carry a 20 uf solen, not a 21. Would I be ok to use the solen 8.2, 10, and 12 wired the exact same way as the original 8, 10, and 11 (so I don't have to worry about my (limited) ability/know-how to change wiring!)? The solens are +/- 5% compared to the original (Chicago Condensor Corp.) which are +/- 10%. Have I heard right that replacing the original 50 vdc caps with the 400vdc caps isn't anything to worry about--just gives you more headroom?
Thanks again,
Dave
Also, is the condition of this "copper" anything to worry about?
That's not copper you see on the outside, it's a layer of paper. Inductors don't have value drift over time like caps, so they'll be fine.
Yes, the value of capacitance is the important part, the voltage rating is what it can stand before damage. As long as you meet or exceed the original V rating, you're fine. There's abosutely no reason to use higher V ratings than design, and there's no advantage, you just pay more.
"[I]We're going all the way, till the wheels fall off and burn[/I]!"
Bob Dylan, from [I]Brownsville Girl[/I]
[I]"Time wounds all heels"[/I]
John Lennon, referring to the Nixon/Hoover deportation fiasco.
Quoting bowtie427ss "I'd also recommend replacing the L-pads at the same time" I just had a (crazy?) idea. Since I always leave the L-pads "all the way up" on my AS 101s is BYPASSING the L-pad an option rather than replacing it? Would bypassing The L-pad be just like leaving the L-pad "all the way up" and also eliminate any distortion being caused by an old L-pad (or would bypassing the L-pad change the impedence or sound or cause some other undesired effect)? If I replace the L-pad rather than bypass it, will any 8 ohm L-pad do? Do I just wire the new one exactly the same way as the old one? Here's a link to an L-pad at parts express that I found--but I still like the idea of bypassing the L-pad altogether if that won't cause any undesired effects.... Parts Express:L-Pad 100W Mono 3/8" Shaft 8 Ohm Does anyone out there know if bypassing the L-pad is an option and how difficult would that be to do? I would leave the old L-pad where it is but not have it wired to anything?
VOTT, indeed you can bypass the L-pad and let the horn run wide open if that suits your room and listening tastes. Some folks swear by installing a fixed resistor network to simulate the L-pad in their preferred position. Either option has it's advantages as well as disadvantages. I like to keep them the way Altec made them in most instances.
I "think" the networks in your 846A Valencias actually use a pot in a slightly different circuit instead of an L-pad, the whole mess is potted in a can of tar like stuff that you really don't want to deal with unless you have to.
Essentially "any" 8 ohm L-pad will work, i'd opt for a minimum 50 watt rating, 100 watts is what i think most of the stock Altecs were. If you can find "Violet" brand, you've hit paydirt. I've also pried them apart in the past and manually cleaned the wiper and resistive coil with some success on the large ceramic pads.
Not all vegetables make good leaders.
OK, I'm going to try to bypass the old L Pads first, listen to see if there's a difference in sound afterwards, then I'm going to order the new caps--replace those and listen again for any improvement--and then I'm done (hopefully!). I'm figuring that doing this kind of stuff one step at a time and then evaluating any difference after each step will be the best way for me to know how much difference (if any) each step makes. Here's my dilemma. There are 4 terminals on these old L Pads. If I'm going to bypass them, I'm going to leave them in place just so I still have all the "original equipment" but I want to disconnect every wire from them to be sure they're no longer affecting the sound (since I leave them turned "all the way up" anyways). I have no clue which wires to connect to which wires to achieve this bypass (and I don't own a defibrillator)... Here is a visual--I need help! (an understatement)....All of the following description applies to the above photo--I added the photos below just to give more of an overview. As you can see in the above photo (hopefully), there are two upper and two lower terminals on this L Pad. I'll refer to the upper terminal that's closest to the camera as upper near, and the further one as upper far etc. (these LPADS look really corroded). OK, to give you a frame of reference, there are three wires soldered to the upper near terminal of the LPAD. The red one goes directly to the positive terminal on the horn, and the black one goes directly to the 8 uf cap and a very short uninsulated third wire connects the upper near terminal to the lower far terminal of the LPAD as you can see in the photo (I think it's called a "jumper'?). By the way, that "jumper" is the only thing soldered to the lower far terminal. The top far terminal has only one black wire soldered to it which connects to a post on the crossover frame (body)--this post sends one wire to the 10 uf cap (which looks like it has had oil leak all over it from inside) and A SEPERATE WIRE from the post to the 11 uf cap and a third separate wire from the post which looks like it connects to one of the two copper colored squares (i think it's called an inductor?!). Lastly, the bottom near terminal of the LPAD has only one wire soldered to it which looks like it's connected to the bottom of one of the two rectangular copper colored "inductors"(?). As I mentioned, I want to disconnect every wire from these old L Pads to be sure they're totally bypassed--what wires do I connect to what wires to achieve this bypass? I would really appreciate help on this matter--I have no clue and I really don't want to fry anything etc..... Here's a few more photos in case any of these help--I moved one of the caps for the photos to give you a better view....
Thanks again!!!!!!
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