ADC 303a's have to be opened. How?
- Thread starter Blast
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They sound nice -- a bit more bass than you might expect, though nothing earth shattering since its only a 10 inch woofer in a moderate size cabinet, and fairly smooth and extended upper end, but with a largish cone tweeter, dispersion isn't as great as modern speakers usually have. I would characterise them as sweeter rather than assertive, but not wimpy.
I heard one pair that didn't sound good -- woody and rough -- and I would guess that they might have had bad capacitors, and they were actually 303a, I think.
For 17 bucks a good deal if they are in good shape.
I heard one pair that didn't sound good -- woody and rough -- and I would guess that they might have had bad capacitors, and they were actually 303a, I think.
For 17 bucks a good deal if they are in good shape.
As far as my 303a's are concerned I haven't gone any further with them- the plates are still hanging out of the back like in the photos.
I lost my job right after (or about) the time I got the speakers so things have been tough with no extra cash to throw around my hobby. Next step is to cut the backs open and consider repairing one, or replacing both woofers.
Brian
Sorry for the slow reply; I didn't see your post until the thread rose up toward the top of the list again this week.
The speakers I was working on were ADC 303B's. The drivers are screwed on from the front. Ditto for 303AX's.
Apparently that can't be said for the 303A.
No problem. Somehow the option to subscribe to threads I reply to got turned 'off'. I lost my list of threads to watch and I feel like I'm missing replies elsewhere, myself.
If I remember correctly the only drivers I noticed were screwed in the back were the woofers. Can't remember if I checked the others, or not.
I think my ADC 303ax's crossover has the most tar on them, do I win a prize? :tears:
So: any luck removing the tar or should I just look to install a new binding cup and crossover? I'll have to study Nat's description of the cap and resistor values then draw up a schematic to make sure I understand it correctly.
My only other re-cap experience is with the ultra-simple EPI 100. I know the 303ax is a completely different speaker, but is it possible that the original crossover could be distilled to a circuit that's just as basic?
So: any luck removing the tar or should I just look to install a new binding cup and crossover? I'll have to study Nat's description of the cap and resistor values then draw up a schematic to make sure I understand it correctly.
My only other re-cap experience is with the ultra-simple EPI 100. I know the 303ax is a completely different speaker, but is it possible that the original crossover could be distilled to a circuit that's just as basic?
Attachments
Ok, cleaned off the black waxy tar but both of the aluminum plates took a bit of beating coming out of the cabinets.
I've attached images of the cleaner crossover and what I believe to be the correct schematic. I have only one capacitor, 6µF 50V, and one resistor, 5.6Ω (green, blue, gold, silver).
"tysontom" over at classicspeakers.net has records for a 1500Hz crossover point for the 303ax.
In my attached images you can see that I managed to break the connection for the ironcore inductor, but I can clearly see in the other one that it connects to the negative terminal.
One issue for me is that my multimeter doesn't read any resistance across either tweeter's terminals. The woofers read about 6Ω. Could my tweeters be burnt resulting in an open circuit?
At this point, I'm not sure what I'll do next, the cabinets, grills and woofers seem to be in decent shape... maybe new terminals and simpler crossovers.
I've attached images of the cleaner crossover and what I believe to be the correct schematic. I have only one capacitor, 6µF 50V, and one resistor, 5.6Ω (green, blue, gold, silver).
"tysontom" over at classicspeakers.net has records for a 1500Hz crossover point for the 303ax.
In my attached images you can see that I managed to break the connection for the ironcore inductor, but I can clearly see in the other one that it connects to the negative terminal.
One issue for me is that my multimeter doesn't read any resistance across either tweeter's terminals. The woofers read about 6Ω. Could my tweeters be burnt resulting in an open circuit?
At this point, I'm not sure what I'll do next, the cabinets, grills and woofers seem to be in decent shape... maybe new terminals and simpler crossovers.
Attachments
They looked tarred AND feathered so you've got a shot at the grand prize...
Simpler crossovers- exactly- that's what I'm going to do. Wire up the same components but without the switches (I never use switches on the backs of speakers, anyway) and nice binding posts.
Although the possibility of open tweeters is there, the probability of BOTH being open is less. Try them on something else to be sure. I don't know, now that I think about I blew both tweeters in my Infinity RS1001's by touching the input tip on the amp while it was turned all the way up. :stupid:
But none of this work is going to happen on my 303a's until I can buy something more than a mortgage, utilities and food. This economy SUX!
I hear ya, from May 2007 until June 2008 I was in the laid-off->unemployment->part-time/semi-full-time contracting->full time job cycle.
I really liked the retro graphic design of the back panels and wanted to keep them, but as my wife pointed out, you really don't see them very often.
Now that I'm back in the money 
I'm moving forward on the repairs of this pair of ADC 303a.
Since I found it was not going to be possible to remove the woofers without opening the rear panels I decided to cut along the "green line" as I illustrated in an earlier post in this thread.
I did so and created a opening:
The hole is ample in size to examine the tweeter and remove the woofer, yet allows enough surface area to place a sealed cap to re-close the box when repairs are complete:
Originally, I thought I could make out an odd shaped dust cap through the front of the grille cloth. Turns out it was actually tape that covers rectangular cut-outs near the center of the cone. Maybe this is the "Frequency Discriminating Decoupling" on the "high compliance woofer" as stated on the rear label.... Whatever it is, I've never seen anything like it before:
I'm moving forward on the repairs of this pair of ADC 303a.Since I found it was not going to be possible to remove the woofers without opening the rear panels I decided to cut along the "green line" as I illustrated in an earlier post in this thread.
I did so and created a opening:
The hole is ample in size to examine the tweeter and remove the woofer, yet allows enough surface area to place a sealed cap to re-close the box when repairs are complete:
Originally, I thought I could make out an odd shaped dust cap through the front of the grille cloth. Turns out it was actually tape that covers rectangular cut-outs near the center of the cone. Maybe this is the "Frequency Discriminating Decoupling" on the "high compliance woofer" as stated on the rear label.... Whatever it is, I've never seen anything like it before:
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Woofie
New Member
I was impressed with Goldwood drivers.
Was given a pair of L-19 cabs, without the 116's, so I stuck a couple of those in the great results. Don't have anything to compare them to, but the price was right for the GW-8PC-30-8 @ 30 bucks a pop. Bought four of them and got them shipped for free.
