My new-to-me 820s

Yesterday was moving day for the 820s. These belonged to my audiophile uncle - who drove off to the great sound stage (and car show) in the sky last year. He bought one of the 820s new in 1956, and the other one used about 10-12 years later. The 'new' one has the Little Maestro emblem on it, and the 'used' one is a little older and has the ALTEC decal at the top.

I will have more comments, questions, and photos soon. But to whet some appetites, here is something interesting: My uncle always said that the two sounded a bit different. One was a little better on the low end, and the other was a little better on the high end. He used an equalizer to cover it up.

When we loaded them up, I laid them on their sides. And check it out. There are a number of construction differences between the two. One in particular stands out: the 'used' one is tuned using holes - like the plans in the speaker building book. The other (the 'new' one) has an angled piece in the rear.

I should note that I once asked my uncle if one was a 820C and the other a 820A. But he insisted they were both 820Cs. Same horn, woofers, and xover. I need to remove the side covers to confirm.

I wiped off the dust and debris. Then applied some Liquid Gold wood cleaner and preservative. The 'newer' 820 cleaned up really well, though there is an area at the bottom of the grill where the dark finish has disappeared.

The 'older' 820 has more problems. Part of the right side lived next to a single pane sliding door for 30 years, and got quite a bit of sunlight. The finish is almost completely gone. Just some flakes remain.

Does anyone know what kind of dark finish Altecs of that era used? I will most likely call in a professional furniture restorer, because there are a few chips in the veneer that also need to be fixed.

Those are some sweet cabinets, and I find the reflex port differences to be very interesting!
Can you post some pics of insides? Love to see the drivers and if there are any other cabinet differences.
There is a 820 thread over on LH where many plans are posted about this and other classic corner horn cabinets.

The plans shown on Post #2 by Tom Brennan of that thread show the actual part number of the grill cloth used on the 820, so it is conceivable that the finish part number may also be mentioned in that book? I don't have the book, but I would bet someone here does (it's very well-known).

I have a copy of the Badmaieff and Davis book. (13th printing, 1978.) The final chapter is all about construction and testing techniques. Just looked and it says very little about paint - other than painting the baffle board and screw heads black like the drivers so that they don't show. They also mention coating the interior with shellac to capture dust/grit left over from construction.

The finish is not oiled. I suspect it is some sort of varnish or laquer. But I really know very little about woodworking, so really need to get a pro in. I am wondering if whatever product was used can still be purchased here in California. I know that these days a lot of people buy cabinets that are made outside of California due restrictions imposed by our (fill in the blank...) environmental laws.

I hooked them up last night. It has been at least 15 years since my uncles system was totally operational, so I haven't heard them in their full glory for a while. Man, that 'presence' really comes through! Stereo imaging is terrific. For all those woofers and big cabinets, the bass is a little weaker than I remember - but clean. Could be a problem upstream though, since I was in a hurry and just used the kids X-Box 360 HDMIed into a Sony Bravia TV as a DVD/CD source.

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Originally Posted by wws944

... For all those woofers and big cabinets, the bass is a little weaker than I remember - but clean...

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Update: So much for being in a hurry last night. It seems I wired them out of phase... Bass is where it should be.

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Originally Posted by wws944

One in particular stands out: the 'used' one is tuned using holes - like the plans in the speaker building book. The other (the 'new' one) has an angled piece in the rear.

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Early cabs should have holes [many small ones originally] and the fiberglass wedge since the Fs of early 803s were 50-60 Hz. Later ones dropped to around 35 Hz, so would be tuned lower with just the wedge covering a solid plate vent, which begs the question, what are the date codes? They will be 391xxx.

GM

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Originally Posted by wws944

The finish is not oiled. I suspect it is some sort of varnish or laquer.

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Finish would normally only be listed on purchase order docs, not assembly drawings except for painted finishes.

Lacquer was the preferred coating with Ga. cabinet, furniture manufacturers until EPA stopped them in the late '70s IIRC, but no clue about Ca. other than such changes originated there.

GM

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Originally Posted by GM

Early cabs should have holes [many small ones originally] and the fiberglass wedge since the Fs of early 803s were 50-60 Hz. Later ones dropped to around 35 Hz, so would be tuned lower with just the wedge covering a solid plate vent...

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I want to say that the older cabinet is a 820A. Except check out the photos at the following:

1953 Altec 820c

He calls it a 820C, yet it has 803A woofers and holes at the bottom. But it also has a 811 horn and 802C driver. So it seems there was an evolution - horn evolved first, then the woofers.

Think I will pull the side panels off the older one this weekend to confirm which drivers and xover it has. I bet it looks like the one above.

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... which begs the question, what are the date codes? They will be 391xxx.

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On the drivers or the cabinets? There are no numbers on the outside of the cabinets.

Right, the HF horn was switched out early on.

803A should have the lower tuned cab.

On the cabs, though in the link, that particular cab was rubber stamped, so whatever you can find: 025

GM

I took a side panel off each one this morning. My uncle was right - they are both called 820Cs. Both have 802C/H-811 horns, 803A woofers, and N800D crossover. In the older one, the components are painted dark gray, and the newer one they are Altec green.

Both have schematic diagrams on the interior of the side panel. On the older one, the drawing is dated 8/30/54 and is noted as "Issue 1" - which I would take to mean it is the first version of the 820C. On the newer one, the drawing was redone. It lists itself as "Issue 2" with a date of 2/31/55, but then also shows an 11/14/55 revision date as "Issue 3".

The 803As on the older cabinet have a date code of "3-55" and have "20409" stamped on the cones. The newer 803As have a date code of "May 1957" and have "20750" stamped on the cones. (Looks like my uncle bought it in 1957, not 1956.) I didn't see any date codes on the 802Cs or the horns.

Note in the photos that the crossover is mounted on the shelf on the earlier version, and next to the horn on the later version.

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Originally Posted by GM

Lacquer was the preferred coating with Ga. cabinet, furniture manufacturers until EPA stopped them in the late '70s IIRC, but no clue about Ca. other than such changes originated there.

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And in fact I looked through the Badmaieff and Davis book a bit more. In one of the other chapters, they talk about using a laquer finish. The 820 cabinets only came in blond or mahongany. So I think we can safely say it is a "mahogany laquer" finish.

Interesting! It seems almost like these were assembled somewhere other than the factory as the 391 manufacturer date code goes back to WWII. Even more head scratching is they were still building the 'A' with an 'Iconic' label, 811 horn as late as '56. This still doesn't explain the difference in vent design as the woofers should all be pretty much identical through this period.

I presume these have N-800-D XOs.

GM

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Originally Posted by wws944

So I think we can safely say it is a "mahogany laquer" finish.

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Works for me! ;)

GM

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Originally Posted by GM

Interesting! It seems almost like these were assembled somewhere other than the factory as the 391 manufacturer date code goes back to WWII. Even more head scratching is they were still building the 'A' with an 'Iconic' label, 811 horn as late as '56. This still doesn't explain the difference in vent design as the woofers should all be pretty much identical through this period.

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When was the move from Beverly Hills to Anaheim? Maybe the newer one was built somewhere else. It certainly seems to have a bit higher level of construction detail. Except for the wiring - which is a bit messy compared to the earlier one.

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I presume these have N-800-D XOs.

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Yep. I confirmed that both are N800D, and that is also what the schematics show. Different cosmetics though.

Also note that in the link I provided back in post #8, that his cabinet has both holes on the bottom and the tilted triangular piece in the corner. In mine it is holes-only in the older cabinet and triangular piece-only in the newer one.

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Originally Posted by wws944

Also note that in the link I provided back in post #8, that his cabinet has both holes on the bottom and the tilted triangular piece in the corner. In mine it is holes-only in the older cabinet and triangular piece-only in the newer one.

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I noticed that same detail! Do the labels in both of your C's show Beverley Hills?

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Originally Posted by Alien_Shore

I noticed that same detail! Do the labels in both of your C's show Beverley Hills?

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Both show Beverly Hills on the schematic diagrams on the inside. The newer one also has an "Iconic" label with Beverly Hills address on the outside of one of the side panels. The cabinet in the link in post #8 has the exact same label. But the label is missing on my older cabinet.

My newer one also has an envelope glued to the side panel containing a diagram of how to remove the side panels and undo the nuts holding the front grille piece to the cabinet. Needed for narrow doorways... The older one appears to have had that same diagram glued to the rear (as the one in the link does), rather than in an envelope. But at some point in the past it disappeared too. I can see the glue residue from where it used to be.

The site mentioned in post #8 also has a page documenting a 1951-era 820A, at: 1951 Altec 820a The schematic diagram is dated 3/14/51. So shortly after this must be when 820s started production.

It has both holes and the triangular piece at the bottom. Now I am wondering if my older cabinet is missing the triangular (actually trapezoidal) piece? Next time I open it up, I guess I should look for evidence of it having once been there.

GM: Check out the '20159' code stamped on the woofers. Also the 803A woofers and xover are marked 12 ohms, not 16 ohms. The 802B is marked 15 ohms. Interesting that they didn't change the model number with a different VC impedance in later versions.

Got one estimate to refinish the cabinets. He only wants to do both of them, so they will match. And of course, at twice the price. My opinion is that they aren't supposed to match, and one really doesn't need refinishing. So I have a second guy coming in a few days to look at them...

Another 820 on ebay, this time a single 820C: Altec Lansing 820C Speaker System - Finest Speaker System From Altec - Original | eBay

Someone applied Formica to the cabinet, and painted the grille frame black. Also added the recessed round terminal strip on the back. (Normally, I think the wiring is simply supposed to be inelegantly routed under the cabinet. On mine, my uncle put a couple of brass binding posts on a rear side panel of each one. I seem to recall him telling me about it when he did it.)

His comment about "The cabinet has an original Altec Lansing spec sheet which dated this to early (2-31-1955). We all know there is no Feb 31 in any year. So this must be a rare error dating it such. The only one in the world!" is also present on the schematic in my 1957 820. Check out my photo in post #10 of this thread. Both my 1957 820C and his are "Issue 3" 820Cs.

GM: Note that his woofers have "20409" stamped on the cones - like the ones in my "Issue 1" 1955 cabinet. Though mine are painted gray, and his are green.

Once again, this cabinet has *both* the "holes" and the tilted triangular piece at the bottom. I looked really closely at my 1955 cabinet - and could find no sign of the tilted piece having ever been there. Nor does my 1957 cabinet have the holes.

His BIN price is $2995, but no one has jumped on it. Since someone just paid $7700 for a pair of these guys, I am guessing it is because of the Formica and associated cosmetic changes?

Yeah, only a scumbag eBay dealer would claim Altec had the printer do ONE spec sheet at a time...you can not turn on a printing press for ONE sheet of paper.

Update: I decided to bite the bullet and have both cabinets completely refinished. The fellow who is going to refinish them has been around pro-sound for a long time, and does a lot of custom speaker building. He is taking great personal interest in the project - which is making it a lot of fun.

He brought by some mahogany samples the other day. We determined that the 1955 cabinet has a 'Bombay mahogany' finish, whereas the 1957 cabinet has a 'red mahogany' finish. The Bombay mahogany appears a little more brown, and is also a bit darker than the red mahogany. I decided to have both cabinets done in the red mahogany finish. Then yesterday he brought by more samples comparing satin vs semi-gloss lacquer. The original cabinets definitely seem to be satin, so that is what I am going with. When finished, they will have 14 coats of lacquer on them!

He also applied one of the repro decals to one of the samples, and put a couple of coats of lacquer over it. It worked quite well, but he noted that the decals are very fragile. We are wondering if Radio Daze can print them on a little thicker stock. Panomaniac gave me his blessing to contact them about it. If they can do anything, I will share whatever I find with the group. I may adjust the color a little bit too.

Nice !!!

Looking forward to some pics of the finished product .

:)

Update: My cabinet guy is just about ready to pick up the cabinets for refinishing. Hopefully in the next day or two. We will be removing the drivers and crossovers before loading them up. While out of the box, is there anything I should do with these 55+ y/o components? For example, should I send them to GPA for checkout and possible Alnico magnet recharging?

In particular, I am wondering about re-capping the N800Ds. According to the schematic in TL-121, there are two 10.5 mf caps in each. Considering that the crossovers are fairly simple first-order crossovers, how noticable would it be to simply use commonly available 10.0 mf caps? Or should I get pairs of caps (say 10.0 and 11.0) and wire them to get 10.5?

Also what kind of caps are recommended? I am not terribly budget concious, but would find it real hard to pay hundreds of dollars per cap for fancy Mundorfs.

As far as the decals go, I have decided to use our "group buy" decal with its gold leaf lettering on my 1955 cabinet - rather than trying to get a little closer color match. Will give it a bit of "street cred" with this group, at least. :) (The 1957 cabinet has the Little Conductor emblem on the grill cloth. So won't get a decal.)

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Originally Posted by wws944

Update: My cabinet guy is just about ready to pick up the cabinets for refinishing. Hopefully in the next day or two. We will be removing the drivers and crossovers before loading them up. While out of the box, is there anything I should do with these 55+ y/o components? For example, should I send them to GPA for checkout and possible Alnico magnet recharging?

In particular, I am wondering about re-capping the N800Ds. According to the schematic in TL-121, there are two 10.5 mf caps in each. Considering that the crossovers are fairly simple first-order crossovers, how noticable would it be to simply use commonly available 10.0 mf caps? Or should I get pairs of caps (say 10.0 and 11.0) and wire them to get 10.5?

Also what kind of caps are recommended? I am not terribly budget concious, but would find it real hard to pay hundreds of dollars per cap for fancy Mundorfs.

As far as the decals go, I have decided to use our "group buy" decal with its gold leaf lettering on my 1955 cabinet - rather than trying to get a little closer color match. Will give it a bit of "street cred" with this group, at least. :) (The 1957 cabinet has the Little Conductor emblem on the grill cloth. So won't get a decal.)

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Yeah, you definitely should re-work those tired old crossovers. The difference between a decent cap and the uber-fancy caps is....well, let's just say a matter of preference. My old ears certainly wouldn't tell the difference. Just go to parts express or erse audio and grab some decent poly caps and enjoy the improvement. Regarding the use of 10.0 vs 10.5 uF in a 2nd order XO for 16ohm drivers is <100 Hz. You'd probably be off that much by variances in the Re of the voice coils and other things. In other words, unless you measure all your drivers and adjust your XO to fit those values, you likely won't notice a 0.5 uF difference in your caps. Have you measured your drivers to see if the voice coils are healthy?

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Originally Posted by Alien_Shore

Yeah, you definitely should re-work those tired old crossovers. The difference between a decent cap and the uber-fancy caps is....well, let's just say a matter of preference. My old ears certainly wouldn't tell the difference. Just go to parts express or erse audio and grab some decent poly caps and enjoy the improvement. Regarding the use of 10.0 vs 10.5 uF in a 2nd order XO for 16ohm drivers is <100 Hz. You'd probably be off that much by variances in the Re of the voice coils and other things. In other words, unless you measure all your drivers and adjust your XO to fit those values, you likely won't notice a 0.5 uF difference in your caps. Have you measured your drivers to see if the voice coils are healthy?

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Thanks Alien. He picked them up a few days ago, just ahead of the major storm we've been having here on the left coast. We were in a bit of a hurry, so he is removing the drivers at his shop. Will check them out there.

As I mentioned near the beginning of this thread, I have been feeling like the bass is a bit weaker than it should be. (Even with the systems properly connected in phase...) It is interesting that you mention the 16 ohm load. The twin woofers in the 1955 cabinet are marked 12 ohms, whereas the 1957 woofers are 16 ohms. So considering that they are wired in parallel, we are talking 6 ohm and 8 ohm loads at the respective crossovers. There aren't any capacitors in the bass circuit. Just a 3 mh inductor. So I am wondering if the magnets might need recharging? Alternatively, the treble horns are connected to the 0 db taps on the crossovers. So we could lower them a few db by using one of the other taps. Here of course, the capacitors come into play though. Would new caps avoid moving the taps?

I'd need to see that schematic - I thought that those old 800 networks were series filters, right? Can you take pictures of the crossover and post it? I'd like to see that, too. Most of those multi-tap units just have more (shunt) resistance in series between taps. But I don't know how the coils are laid out.

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Originally Posted by Alien_Shore

I'd need to see that schematic - I thought that those old 800 networks were series filters, right? Can you take pictures of the crossover and post it? I'd like to see that, too. Most of those multi-tap units just have more (shunt) resistance in series between taps. But I don't know how the coils are laid out.

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The N800D schematic appears in Altec Technical Letter 121: http://alteclansingunofficial.nlenet...ers/TL_121.pdf (These Technical Letters really make for some fun reading. My thanks to whoever scanned them!)

Looking at the schematic again, I think my posting above is wrong. The capacitors do come into play in the LF portion of the circuit as well.

Was talking with the owner of a local high end audio shop yesterday and got into a discussion of crossovers for the 820s. Besides the capacitors, the topic of the coils came up. According to the N800D schematic, the stock crossovers use iron core inductors. I was musing over whether air core would be better and he was fairly adamant that air cores are the way to go. OTOH, considering how efficient these horns are, would the stock inductors get to the point where they start to saturate?

If I bought some air core inductors along with the new caps, I may as well just build my own crossovers - rather than retrofitting the new parts into the N800Ds. I would simply follow the N800D schematic - unless someone knows a good reason not to.

I'm gonna do Iron cores on the LF side and Air core on the HF side. I didn't like how the air cores sounded on the LF side. And not real happy with how Iron cores sound on my HF side. I have iron core on both now but the air cores for the HF side will be here Tuesday.

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Originally Posted by cradeldorf

I'm gonna do Iron cores on the LF side and Air core on the HF side. I didn't like how the air cores sounded on the LF side. And not real happy with how Iron cores sound on my HF side. I have iron core on both now but the air cores for the HF side will be here Tuesday.

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That is a useful observation. I guess I would have expected the opposite - since the high power, where saturation might be an issue, would be on the bass side.

Which air cores did you go with?

Ummm I don't remember, The 16 gauge 1.5 Mh from parts express. which is actually up from the 1.1 Iron core Erse I was running. It seems like most crossovers I've seen have the same Mh coils on both sides where I was running a 1.5 Iron Core 0n my LF and a 1.1 on my HF.

Whats the time frame on the Cabinet work? Cant wait to see the pics. Thanks for all your help. Rick

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Originally Posted by johnny_fever

Whats the time frame on the Cabinet work? Cant wait to see the pics. Thanks for all your help. Rick

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Soon, I hope. We were thinking they would be done by the end of December, but Life got in his way.

Update: We spent a fair amount of time this evening marveling over the numerous differences in construction between the two cabinets. Some of which are very visible back in post #1 of this thread.

Measurements of the DC resistance on the woofers are:

Gray (1955 - 12 ohm rated) set: 8.6 ohms + 8.6 ohms measured
Green (1957 - 16 ohm rated) set: 8.3 ohms + 8.3 ohms measured

Compression drivers are:

Gray (15 ohm rated): 8.8 ohms measured
Green (16 ohm rated): 8.3 ohms measured

Do these DCR values seem low? At least they are pretty consistent with each other.

Still under discussion is if we should replace the crossover caps in the N800Ds or not. Both N800Ds have 10.5 mfd caps in them, but he has not had a chance to measure them and see if they are still in spec yet. (As a friend of mine likes to say - "To measure is to know".) If the caps are out of spec, it may just as easy to leave them as they are and build new crossovers. Or maybe bi-amp them? (I could buy a cheap Behrenger active crossover for what new crossovers would cost. I already have the amps.)

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Originally Posted by wws944

Update: We spent a fair amount of time this evening marveling over the numerous differences in construction between the two cabinets. Some of which are very visible back in post #1 of this thread.

Measurements of the DC resistance on the woofers are:

Gray (1955 - 12 ohm rated) set: 8.6 ohms + 8.6 ohms measured
Green (1957 - 16 ohm rated) set: 8.3 ohms + 8.3 ohms measured

Compression drivers are:

Gray (15 ohm rated): 8.8 ohms measured
Green (16 ohm rated): 8.3 ohms measured

Do these DCR values seem low? At least they are pretty consistent with each other.

Still under discussion is if we should replace the crossover caps in the N800Ds or not. Both N800Ds have 10.5 mfd caps in them, but he has not had a chance to measure them and see if they are still in spec yet. (As a friend of mine likes to say - "To measure is to know".) If the caps are out of spec, it may just as easy to leave them as they are and build new crossovers. Or maybe bi-amp them? (I could buy a cheap Behrenger active crossover for what new crossovers would cost. I already have the amps.)

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I wouldn't let the inconsistent labelling worry you what-so-ever .

Those quoted dcr values are quite consistent with drivers having a 12 ohm rating ( which is really what most Altec & JBL components were up until around the early sixties ) .

Some Historical Trivia ( as I understand it ) ;

- It's after this that Altec moved their line of transducers towards a set of "truer" impedance ratings ( raising the dcr to @ 12 ohms for drivers that were rated as 16 ohms & lowering the dcr to @ 6.5ohms for things rated as 8 ohms ).
- JBL took a different tack / they retained those mid 8 ohm dcrs and proceeded to still call their products 16 ohms . They then introduced lower impedance drivers ( some having dcrs as low as 3.2 ohms ) and called them 8 ohms ( while in effect they should have been called 6 ohm ).
- A Lower impedance draw more current & are therefore "louder".
- It's this deliberate mis-labelling ( or marketing "slight of hand" on JBLs part ) that would help trigger some finger-wagging (& put-downs) directed towards them ( ie; "Just Be Loud" being one of the more "insight-full" ) .

:)

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Originally Posted by Earl K

I wouldn't let the inconsistent labelling worry you what-so-ever .

Those quoted dcr values are quite consistent with drivers having a 12 ohm rating ( which is really what most Altec & JBL components were up until around the early sixties )...

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Thanks! One less thing to worry about. :)

Update: Slow progress. He has pretty much completed stripping both cabinets and repairing the veneer. Last week, we discussed replacing a couple of pieces of wood on the bottom of one that had gotten damaged over the years.

In the meantime, here is a photo that my cousin found. It dates from about 1957-1958 - when my uncle first bought his first 820C. Mono at the time, of course. It was taken at my grandmothers house. I very well remember this scene from when I was a tot!

http://www.hostboard.com/forums/hbmc.../2013/03/1.jpg

Update: Last night we had a discussion on grill cloth. He is (carefully) removing the old cloth in preparation for the finish. The cloth is held in place on the removeable nose pieces with screwed in strips of wood. While the old cloth is in decent shape and could be reused, now is the time to consider replacing it. I know that the cloth was replaced on one of them back in the 1980s. At the time, my uncle managed to find reasonably matching cloth. (Knowing him, he might have driven over to Altec in Anaheim... But according to my cousins, he may have found a source in the San Fernando Valley.)

In the Badmaieff and Davis book, they recommend "Newcastle 211-72 aluminum". Since the book was published 10 years after the speakers were built, I have no idea if they are the same or not. Googling around, it turns out that Newcastle is still in business and still making grill cloth. But their product numbers are different than the "211-72 aluminum" mentioned above. I've sent them an email to see if they can identify it and cross reference it to a current product. I also sent an email to Antique Electronics Supply (now called Tubes and More) to see if they have any opinion.

In the meantime, does anyone here have any ideas on what this cloth is?

This is the 1955 cabinet - which I believe is the original cloth:

http://www.hostboard.com/forums/hbmc...2013/03/38.jpg

This is the 1957 cabinet - with newer cloth, but similar to the original:

http://www.hostboard.com/forums/hbmc...2013/03/39.jpg

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Originally Posted by wws944

In the meantime, here is a photo that my cousin found. It dates from about 1957-1958 - when my uncle first bought his first 820C. Mono at the time, of course. It was taken at my grandmothers house. I very well remember this scene from when I was a tot!

http://www.hostboard.com/forums/hbmc.../2013/03/1.jpg

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That lamp and dresser are pretty nice looking, besides the 820 in the corner.

Not sure about the grill cloth, other than I totally agree that you should replace it!
How cool would it be to have a thread of old pics showing new vintage gear in it's prime. That picture is a fantastic example.