Help! New Member Has ALS Ribbon Problem!

The new pix are good - now that I can see the ends, the mystery resistor array is obviously in SERIES, and is therefore a 100 watt 72 ohm resistor, not a 4.5 ohm. I still don't know exactly where it goes in the circuit, but there is enough photo info now to figure it out, I'd say. It has to be on the woofers, someway or other. Problem is, I'm pooped - bedtime has arrived. Tomorrow.

Robert R

mariodawg -

The extra pictures are just what was needed – wonderful!

I finally have the upgrade crossover figured out, I think. Went a bit loony from skipping from one close up picture to another; each one has just a tiny piece of the puzzle, and I can only display one at a time (part of one, actually). All those different angles, and all those wires, disappearing into unfocused nothingness – aauugh!

Anyhow, the crossover is a standard Platinum one, modified. Unless coil L3 turns out to have a part number other than 616-00076-00, I can draw the whole thing. It all makes sense, once you put it together.

The Originals had a ribbon (array of two, technically) that was pretty inefficient, and in the Original crossover it’s obvious that to balance the lows with the highs it was necessary to pad down the woofers somewhat, or else there would have been too much bass. They used a big coil and a 20 watt resistor. Then the new, more efficient ribbons came along. They were some 6dB louder, watt for watt. That’s a lot better; what before required 200 watts now needed just 50. New woofers were blended with them, and a new crossover; thus the Platinums were born.




Robert R

PS – I didn’t realize how much power you were running! Definitely get 150 volt caps for C2, the one that failed, and get them for both sides; the other channel is likely about to go belly-up. If you can’t find 100uf at 150 volts NP, two 50uf at 150V NP in parallel would work just fine – exact equivalent. Just don’t make the classic mistake of thinking like it was resistor wattage ratings and try to parallel two that are rated at 75 volts each – that doesn’t work.

Robert R, you're my Hero! I am working on several outside projects today, so give me a few days to get back to you on the coil info. Come to think of it, I'll work on it today and get back to you later today.

The narrative technical history you gave on these ALS's was awesome! Thank you for your insight!

I've always been a Carver fan, but this technical stuff I just eat up! Makes me want to buy more Carver and Sunfire equipment! And to think how depressed I was when this speaker blew! Now armed with knowledge, it's become more of an opportunity for improvement (both for me and my speakers)!

Sincerely,
Mariodawg!

Well, thanks, but actually a lot of the narrative I gave you was bullshit. I have edited it out, the part about the resistor across the ribbons. It is there, OK, but it is also there on the regular Platinums. That's good. It means that your converted plats are as efficient as anybody's, and the only difference in your crossover is that one capacitor value, C2, 100 uf instead of 150.

You keep mousing around in here and you continue to learn...


RobertR

Robert R,
After much ado about silicon removal, I have that mystery coil part #:

PCI 9413
616-00076-00

It appears your guess was correct.

Back to the Outdoors,
Mariodawg

I'm glad to see you've found the problem and are on your way to fixing it. Soon your room will be filled with the beautiful music that comes from those speakers.

Not really much of a guess. The whole thing is the exact stock Platinum unit except for, would you believe, the one part that you blew. Don't feel bad, though; the same part is famous for going out on the regular Plats too.

I should thank you for the chance to learn a bit more of the Carver story, the chapter on crossovers.

The infamous capacitor that blew is designated C2. It's 100uf in your (upgrade) version, 150uf in the others. Difference in value presumably due to the slightly different woofers, balancing them with the ribbons.


The schematic calls for a 150 volt rating for C2, but yours, and some of the regular Plats, somehow ended up with 100 volt ones. No big problem with amps up to maybe a M 1.0t, but when you get to these monster amps, the voltages can get pretty wild. And, as you say, you have silver 7t's, a huge room, and like it loud.

So find some 150 or even 200 volt NP caps if you can. As I was just telling someone else, you can make up the 100uf from a parallel combination, as long as all the pieces in the combo are rated 200 volts. So, two 50s, four 25s, three 33s - as long as they add up to around 100, it'll work just like a single 100uf. Just twist and solder their ends together.

If you want a schematic at any point, I have it in .pdf format.

Let us know how it all turns out.

Robert R

Hello again!
Yes, Robert R, I would like a wiring schematic, please. I need to have it so I can email to Sonicraft for their capacitor recommendations. I did hear what you told me earlier concerning "opinions" concerning audio-grade capacitors, but I at least want to look at my options and do more research. My speakers sound very clear and clean (well, prior to the cap blowout), there is no doubt. But the woofers aren't as powerful as I'd like, and my woofers and crossovers ARE over 10-years old, so maybe they could use some new caps (I'll be looking to replace ALL the caps as a possibility); and if that doesn't liven things up, then new woofers and going to a straight Platinum crossover set-up is a another possibility.

I'll send pics of my set-up when all is completed. In the short-term, once the cheaper electrolytics are delivered, I'll fix the one speaker and see if there is a difference speaker to speaker---then go from there.

Where ever I go, I'll keep the Forum in the loop so people can learn from my experiences.

My new caps are due in this week. The sooner the better!

Hope You are Having a Great Weekend,
Mariodawg

I'll probably just try to send you the whole file on the Amazings, and the you just go to page 15 for your crossover, remembering that C2 is 100uf, not the 150uf shown.

Incidentally, for your future reference and that of any "technicians" like the last one, the "J" on a capacitor has nothing to do with Joules. It just means a tolerance of +/- 5%. And a K is 10%, not kilo anything. And an M is 20% tolerance, not mega anything. Sometimes I really miss the world I was born into. In those ancient times, when the tol. was 5%, they just wrote "5%". Tricky, huh?

RobertR

Robert, you'd think they'd also write the capacitance somewhere on the can, too.

I'm just grateful J isn't Joules, the way I do math...

Mariodawg,

I just re-read your earlier post and see that you want more bass. A couple of thoughts…

1. Your crossover has just one capacitor that can affect the woofers at all, namely C1. In yours it actually consists of a parallel pair: a 300uf at 150v NP (green) and a 76uf at 100v NP (blue). This combination comprises a 375uf (nominal) 100 volt cap. I say 100 volts, because the limiting member of such a combo is the member with the lower(est) rating. It’s possible that one of these is defective. Check out both channels. A capacitor tester is what you need here; do NOT bridge this like we did on the C2 problem!! You will be shorting out your power amp, a very unsatisfactory idea. What you hear if these open up is an excess of woofer action, but not in the bass; rather up into the midrange. It could be interpreted as a lack of bass, but it’s really woofers acting without their low-pass filter intact, trying to operate full-range.
You could parallel additional capacitance in with the others to determine results. The stock Platinum schematic uses a 450 uf instead of 375. If you experiment, don’t go to extremes. And don't short across the path of those caps already in there!




2. Be sure your woofers are in phase. I don’t mean left speaker to right; I assume you can deal with that. I mean within each channel. It’s a longish shot, but these have been project speakers, so while you’re in there, test them with a 9 volt battery and a pair of short wires. With the amp unattached and the front grille off, connect the + terminal to the red input on the speaker, then the – terminal to the black, momentarily. You’ll hear a click each time you make contact, and when that happens, all four woofers should move their cones in the same direction, all toward the back. If you can’t see them move, feel ‘em. If one is out of step with the rest, reverse its wires at the speaker terminals. And enjoy up to 50% more bass from that side.

Also: You are extremely unlikely to have any problems with the mylar (yellow) trim capacitors. And quite definitely, you will NOT hear anything different for replacing them with so-called audiophile caps. I’d be willing to bet you’d be very hard-pressed to detect whether those caps were even present at all. Their effect is quite subtle.


Happy tweakin’

Robert R

Robert R,
OK, I just want to re-confirm what you just told me: Unlike what was earlier suspected, my present crossover is the SAME as the Platinum Crossover wiring diagram in the ALS Service manual, pages 15-16---Except for:

A. I have two caps on the woofer side rated at 300uF 150VNP and 76uF 100VNP while the real Plat's had a single 450uF 150VNP cap (C1).
B. My C2 cap is 150uF 100VNP while the real Plat's had a 150uF 150VNP cap.

I DO have a copy of this Service manual, so I need nothing else in order to proceed.

Next question: is the Platinum Crossover parts list on page 42 of the Service manual also accurate, except for the cap differences as noted above? Because the manual also has a revised parts list "The evolution REV A to REV E", but it lists two R1's with different ratings, so it doesn't make sense to me (although, nor can I find R6 or R7 on either parts list on my crossover---assuming resistors always look like a rectangular box like R1-R5 do!).

Just filling in the empty spaces in my brain.

I was surprised when you told me I couldn't jump the woofer caps like I did the ribbon caps. Good thing you told me, otherwise....Blammo! Of course, this makes no sense to me why I can jump one cap but short circuit my amp jumping another.

As for your other inputs concerning testing my woofers for correct polarity and such, I will eventually if I have to (referencing your input), but I do not suspect this is the problem. I mean, the woofers have never been touched since new except for my installation of the Platinum upgrade crossovers (which BTW I noticed the crossover wiring is made of a thicker gauge than the original woofer wiring). So I will experiment with the black and red crossover output wires to the woofers when I reconnnect everything as i may have crossed them 10+ years ago (paperwork long gone), and see what happens (should be no Blammo, right?).

Thanks again for the help!
Mariodawg

Good - I don't have to figure out how to send that diagram!

A. -Correct
B. I thought your blown C2 was 100uf, not 150uf. So confusing, this business of microfarads and watts. Wasn't your blown cap 100uf at 100V?

As to resistors, with series resistance you simply add. R6 and R7 in the drawing were 36 ohms each, giving 72 ohms. By the time they produced yours (which is very late in the Platinum run, right at or maybe even after the end), these were replaced with four 18 ohm resistors, that series foursome that you had to lift to confirm the part number on that coil, remember? Think of that foursome as R6 and R7. It is electronically equivalent, but has a total power rating of 100 watts, making it lots more rugged that the original earlier arrangement shown in the drawing. If memory serves, those two were just rated at 20 watts each; they would have had to be 50 watts each to equal the power handling of what you have.
However they did it, this resistance just reduces ribbon gain, presumably to match with the woofer output.

Now, you have another foursome of identical 18 ohm , 25 watt resistors in there, stacked vertically, but notice, on them the ends are all soldered together. This is the parallel arrangement, and here you divide. So this foursome isn't 72 ohms, it is 4.5 ohms, but still 100 watts rating. The wattage simply warns you of how much heat it can dissipate before it melts down and fails. Here it is 25 watts per single unit, and you have four units, sharing the load equally.
Before they drew the version of the schematic that we have, its pretty obvious that Rs 1,2,4, and 5 were, like 6 & 7 later, made up of just two individual resistors, called R1 and R2. So the next resistor they named came to be called R3, in an unrelated location. Later, when they changed R1 and R2 to a four-unit combo, they named the individual parts R1, R2, R4, and R5, the name R3 having been taken already. Presumably, a later re-draw of the exact version we have here would show R6 an R7 with an R8 and R9, all four together.

By the way, speaking of power resistors - those "box" shaped things, these can get very hot, too hot to touch, and survive just fine. They do have a limit, of course, but nothing for you to worry much about with music.

Interestingly, if you compare page 15 to the Silver Edition crossover on page 11, you'll notice that there is no resistor at all across that ribbon. Apparently there was no need of one to correct balance.

As for the woofer phase tests, it takes only a little time to be sure; just crossing the t's, I suppose, but there were known cases of brand new units getting out into the field with a woofer wired backwards, and there might just still be a few unknown cases left out there. Anyway, when anybody complains of a lack of bass in the Amazings, I always feel it would be irresponsible not to recommend that test. You might find them all in phase but locate one having a shot voice coil, too - not moving at all. There are seven others to cover up problems, remember.


Rob

Mariodawg,

One more explanation. When we started on this project, remember I took care to tell you to substitute another NP cap across the smaller of the NP cps, not to jumper it. Even went to he point of asking you to borrow from the other channel, though I can understand why you didn't want to try that. There was a sneaky reason behind all that, and I think you can understand it now. I was very leery that you might jumper C1 instead, and give your amp it's first taste of a half-ohm load. So we lost some time, but it was for safety's sake. Later, when thanks to your efforts I had a better description of the version of crossover you had, and when I was sure you knew your way around it well enough, I said go ahead and jumper it, because I needed to show you that I knew what the problem was before you wasted any more time or started changing out perfectly good parts at random.

One look at the schematics and the logic is inescapable. There are model and generational differences, but at the end of the day they all have one thing in common: The entire ribbon signal goes through this coupling capacitor known as C2. If woofer yes but ribbon OK though silent, then no C2; end of story. It's either open, or unsoldered. And old NP electrolytics crap out a lot oftener than old solder connections. So I pretty much knew what it was from my first email; it's a very simple diagnosis.

Now, the fact that I didn't TELL you that you could risk shorting your output was an omission calculated to not confuse you, and, more to the point, not to unnerve you. You were even worried about electrocution at one point, and I was worried you'd chicken out and quit. But you hung in there and did everything asked, so here we are, about done. Great going! My part was easy compared to yours, believe me.

Rob