Do you ADC 18A ? anyone?

[billyunderhi]

Its below 20 below zero here in Minnesota... and icy.

So I decided to drive 15 miles to look at a pair of speakers...which I bought.

They are in the back of the van right now and I will be unloading shortly...

My question is - does anyone have any information on ADC 18A speakers?

I have ADC as Audio Dynamics Corporation... and the seller showed me a post on here that showed the ADC 18 speaker... these are different...

They sounded very nice with the reciever he had hooked to them - voice and music from the radio was great - very clear ...

I'll post some pictures after I get them unloaded.

They have an unusual oval woofer - poly styrene... with a rubber gasket.
about 10" by 18"...

Does anyone have any information about this company?

Pics as soon as I can get them out and set up... can't wait to here them with a little tube amp powering them...

 

[billyunderhi]

Audio Dynamics Corp 18A speaker SPECS PICS

ADC 18A Speakers​

Audio Dynamics Corporation - NEW MILFORD Conn​

Walnut Cabinets - Approx 39" High - 27" Wide - 16 1/2" Deep

Slip in Grill cover - Ported at bottom - Walnut and Walnut Veneer - MDF Back panel - Particle Board around Woofer

Impedence: 8 Ohm
Response: 20 - 25,000 Hz + or - 3DB
Wattage: 100 Max


High Frequency: Wide dispersion mylar dome tweeters

Mid Frequency: Highly compliant 5 1/4" midrange drivers

Low Frequency: Rectangular Polystyrene Woofer approximately 18" by 14"



MATCHING SET - Serial Numbers 13613 and 13616



Any interest in seeing the interiors?
It was too cold to take them apart tonight.
Soon as I can I'll try and add driver numbers - I think the lower base may be a seperate chamber... 3" port in the bottom

 

[sealy]

Try reducing the size of your photos and posting them again. Everyone here is always interested in what someone else has.

 

[billyunderhi]

Anyone know anything about ADC?

http://www.audiokarma.org/forums/showthread.php?t=137732


Hopefully the above links to another Thread concerning the ADC company.


Well - last night I tried to remove one of the woofers...

I think they are similar or the same as KEF 139 series woofers...

I just don't get the polystyrene ...

The back panel is sealed not screwed or pinned and I can't open that up...
The panel around the woofer is screwed on but - it must also be glued or sealed because I couldn't wedge the panel out or off.

Anyone have information on these speakers?

I am wondering if the woofer on mine are re-done by someone or if they are factory correct...

They do not sound good through low wattage tube pre-amp set up. (update - found bad channel on this little RCA tube amp which could explain sound problem)
They sound OK through A Pioneer tube reciever...

They sounded great through the Pioneer solid state SX 450... Wilco and then Boz Skaggs really had a depth that my other stereo set up does not bring out.

They were very loud in a 20 by 26 shop
- at about 3 notches on the volume.

I would like to get them into the house and play them over carpeted floor versus the shop concrete...
Unfortunately the wife is not in love with them at all...

These are some big pieces of furniture.

These things could really play loud if they were asked to.

 

[Nat]

Don't know whether to be glad or sad that all the oddball ADCs seem to be in the midwest where I can't buy them, rather than in Connecticut, where I am, and where ADC was -- no room and no money, so don't need them, but ADC was one of my first audio enthusiasms, and weirdo speakers are a passion.

I don't know of any relation between the ADC styrofoam woofer and the KEF B 139. There was a good deal of interest in styrofoam as a material for speakers in the early 60s (especially in England). The combination of stiffness and low mass was attractive, and it was found that a layer of aluminum foil laminated with the styrofoam would control a fierce resonance (400 Hz, I think I remember), and that then the behavior was very good. Leak used the combination in the standard cone shape in their Sandwich woofers (and advertised their strength with pictures of Leak himself standing on the cone, so great was it's rigidity (though he wasn't that big of a guy)). IMF had the styrene pressure woofer that had a center suspension, and looked, if memory serves, like a giant dome. ADC had that big squarish woofer and then KEF came along with the B 139, which for a while was widely considered the best woofer around. There were other styrofoam drivers, some of them truely wretched like the panels that used to be sold to be used full range without a cabinet.

I'd like to hear what you think of the speakers after recapping etc.

 

[klama2006]

"Do you ADC 18A ? anyone?" Nope, but if I ever found a pair that looked as nice as yours, you better bet I would.

 

[billyunderhi]

Recapping

Hey Nat - or others who might know...

I have never recapped a speaker before. I think I'm up to the task, I can figure the values of the resistors and caps...

Does anyone have a recommendation for good/not too expensive Caps for speakers?

Also - any suggestions on gauge of wire...?

I have a set of speakers done with what looks like brown and balck lamp cord.

Thanks

 

[Nat]

You have to get into the speaker to get at the crossover. Usually this involves removing the woofer and working through the hole, but some speakers have removable backs. At any rate, once you can see the crossovers, you read off the values of the capacitors. My recollection of the ADCs 303AXs I found at the dump a while ago was that the crossover components were all wrapped in masking tape which has to be removed to see and to do any work, and that some ADCs have black mastic over the components, which will make it difficult to find the values needed -- you'll have to remove the mastic, which will probably involve heat and or solvent, though not a the same time, and you can destroy the markings if you aren't very careful. So let's hope that isn't the situation with yours.
People speak highly of the Part Express Dayton film capacitors, and they are sponsors of this site, and reasonably priced, so they'd be a good place to start.
My memory is that there were a bunch of carbon composition resistors in the 303AX crossover, and generally wirewound resistors are thought to be better sounding, so they might be worth replacing at the same time.
One final issue -- I remember a post about ADCs which mentioned a capacitor or resistor located on or near a driver, rather than at the main crossover, so check (if you can't stick your head inside or use mirrors, pull the individual drivers and look at each).

 

[billyunderhi]

Crossovers

Thanks Nat -

Yeah I had tried to get the oofer off the other night... shops not heated.

All the screws holding the woofer panel on came out but it is still tight - not movable. I will see about a small prybar -

The back panel is glued in place - I just hope the woofer panel was not glued and screwed in...

These are fairly tamper proof speakers.

The Mid range was easily removed and the wiring did not look suspect there.
Although there was some corrosion on the magent and metal parts... not rust just whitish scale.

I'll post before and after when I get the woofer removed.

Thanks for your suggestions

 

[billyunderhi]

Any Thoughts

:scratch2: Ok - Anyone out there work on ADC speakers before?

These things cannot be opened - not easily anyhow.

I don't want to damage them - the back is glued on and the bottoms are too.

The Woofer screws come out easy enough but then the rectangle piece of wood around the woofer does not pry out.

I don't want to cut them to recap them - and I do want to recap.

Any ideas out there?

 

[kfa888]

Missed this the first time around. Cool speakers. How are you liking them not that you have had them a bit?

 

[BmWr75]

Think I have an ADC graphic EQ bought in the 70s. Have never seen any ADC speakers though.

Nice foil covered woofers though.........

 

[billyunderhi]

The sound is very good - they have an excellent stage presence or imaging but - I think they could do for a recap to clear the mix between bass and tweeter high end.

The back of the midrange has some corrosion in the magnet and I think the tweeters probably will have the same ... They are puttied in very well and dampened agaist vibration and I don't want to crack the seal until I can do the full recap.

They are definately better than the 80s Sansui I have and they beat the Bozak I have as well. But the Bozaks need racapping even worse so its not a fair comparison.

The Sansui sound good - they just sound like box speakers and do not fill the room as well as these ADC do.

I have yet to hook them to a good wattage tube amp... I am using a pioneer SX 450 with them. I think the tubes will bring out something grand.

They are a very nice looking speaker IMHO.

 

[BPFisch]

I can't speak for your 18A's specifically, but ADC typically did one heck of a job sealing up their speakers! So much so that it's near impossible to get inside them without cutting them open. If you do a search you will find a couple past threads about members trying to get inside their ADC 303ax or 303 Brentwood, only to find that they have to cut a hole in the rear panel to access the crossover.

I have a pair of the little ADC 404 speakers. They are just fantastic for their size, but could use a recap at this point in their life. I'm putting it off because there is simply no way to get into them without cutting into the back panel.

I hope you can find an easier way, but I'm not betting on it. If you do find that you have to cut into them, there are ways to do it that can make it look factory (or close to it) and will be easy to replace and reseal.

Good luck and enjoy those ADC's!!!

 

[billyunderhi]

Sawzall nurse....

Sledge Hammer...

Time for some delicate work.:tears:

I think I will try to drill through the rectangular frame holding the Oval Woofer and see if I can get an L shaped piece of metal into the hole to pry the thing off.

Hopefully they did not screw AND glue the thing in place.

 

[beekeo]

I managed to damage the aluminum back panel in my 303ax's so I'm forced to go with a new binding post cup (was thinking of eliminating the tone control switches anyway). It was glued and stapled in place, so the thin metal tore and bent at every fastening point.

In regards to the black mastic/tape: if you have this coating your crossover panel, a hair dryer will soften this stuff up enough to scrape and peel off without damaging the components, just go slowly.

 

[bakes]

If you can get out the midrange, you might be able to get a Wonderbar through so that the L shaped end is pointed squarely at the back of the woofer magnet, then genly push on the straight end against the cabinet above the midrange hole using a lever action so that it comes out. I'd wrap the Wonderbar in foam and duct tape on both the business end and where you press against the cabinet so as not to damage anything.

No idea if this would work or not.

 

[billyunderhi]

Hey - Great suggestions... Thanks alot.

I have heard about the black tape affair and it doesn't sound too pleasant.
The hair dryer trick will be used.


The wonder bar idea would be good BUT ---- BUT....The mid has its own little resonant cavity. No access to the large cabinet.

It does give me a thought tho - the port on the bottom of the speaker -
If it doesn't have a bend in it - I might get some leverage there.

I'll be checking on that tonight.

I'd really like to get these open and see if they are marked KEF -
I'll put some pictures up If I can get them open.

 

[billyunderhi]

Adc code numbers ?

:headscrat Anyone out there able to decipher speaker code?




ADC Speakers have the follwing codes... (pictures to follow later on)

Tweeter...(Plastic?) Dome ... (The later models could be aluminum)

S800 261
(2?)37 450

WOOFER - Full styrofoam Cone with styrofoam face. Mylar wrap on exterior.

0800 16
1056 833

Both Driver Magnets are completely enclosed in a square-soldered or sealed square back. The woofer had a sealed Dustcap over the magnet.

Its gawdawful taking these apart. The woofer plate is a seperate piece of plywood. Its the only area on the 18A speaker that has screws. Remove these OUTER screws - the screws just around the rectangle plywood speaker plate come out completely.

The Inner screws closest to the woofer may actually be carriage bolts Holding the magnet assembly to the cone and to the speaker plate.

The Large plate of plywood has a caulk gasket applied around its recessed eadge. These may be hardened like glue - or, they may have just been glued in place.

I took a soft rubber mallet and loosened the edges and corner with a few judicious whacks. I did put a sock on the plywood where I whacked... Then it was razor blade gasket release time. Razor blade and ballpean hammer all around the outside edge to loosen the seal which is debateble if it should be done or was effective. I think it allowed the prying to work, or maybe it just led to prying after it didn't work.

I ended up taking a chisle and prying one corner until I could get the chisle in along the rebbated ledge. Slowly - After several cuts and a decent blood blister I was rewarded with the strangest sight I ever did see.

 

[billyunderhi]

Guess I have exceeded my picture quota... Unable to upload without first deleting

I suppose that is why so many threads loose pictures after awhile.:scratch2: