Thanks Dan, I'm inclined to do a simple re cap with high quality parts, then brace and refinish the cabinets... original finish was a gray paint. I may paint or even veneer them. Then the horn could really use to be damped, pondering how to do that attractively. Still wonder if its all worth my time. |
Thanks Ralph, yep, I've damped many a horns, but these are exposed and I'll either need to cover them or figure out some way to make them look reasonably attractive. I typically like butyl tape on these, but that would look terrible. As far as the diaphragm, I haven't pulled it, but I would have to assume that it is Aluminum, my buddy bought these in 1969. |
Thanks John, I have 416A, not sure of the horn driver, but the horn is a 511b... Have you done any work on these? I'm wondering if anyone has done impedance correction on both drivers and resonance compensation on the tweeter. I could easily do this and keep the original crossovers in place. I'm thinking it would be very audible. |
Thanks to all of you guys. I have just opened the back for the first time. The tweeters impedance is not marked, but DC resistance is 8.1 ohms. The woofer is an 16 ohm 416A...
The Crossover is an N500G. I can do little to the crossover, everything inside is covered in some sort of goo, at first I thought it was epoxy, but it isn't that tough. Caps look to be film & foil low voltage parts, then there is 1 - 2mfd mylar...
I'm going to go ahead and put 400v poly props in place of the film & foils and 1mfd poly & 1mfd styrene in place of the 2mfd mylar, put some high grade wiring in and start there. I appreciate you guys. Tim |
Broke away the encasing, measured all the parts, Measured all new parts and put together matched pairs for both crossovers, replaced the aluminum foil caps (very rare), and mylar cap, replaced resisters with mills, hot melted all in place in the first crossover. The parts are all matched & soldered for the second crossover, I'll tackle that in the next day or two and let everyone know. All I've done is replace crossover parts with High quality parts. If I get the gumption, I'll take full measurements and possibly add compensation circuitry... Don't know. |
Hello all, as discussed earlier, I have replaced all the caps & resistors in the crossover with upgraded hand spec'd parts with less than 1% tolerance from one channel to the other. The improvement is not subtle. I've given these a couple hours of listening and they continue to improve..If anyone out there has A7's, this is a modification well worth the few dollars, clear improvement in the upper midrange through the treble region as well as a some improvement in soundstage and noticeable improvement in detail also.
I know that the recommendation by one above is to "get over it" and keep them, but they are just too big. So I'm back to the original question. Am I spinning my wheels and wasting my money to do any more work on these, or am I just better off to sell them as is? |
Quote: "Only you can decide a forum can't do it for you"
Hi John, that has always been the case, but the advice (including yours) can help and is appreciated.
I'll figure something out with them, Thanks, Tim |
Thanks Richard, the crossover did a great job of taming the midrange honky/shoutiness. There is the slightest bit left, but very minior and I believe horn damping will end that. After the crossover change, the lower midrange on these is just superb and the upper midrange oddly enough is a bit laid back. I did not expect that. At this point... in my room, I would not consider adding a EQ, but truly appreciate the input, Tim |
Hi Guys, thank you for all your responses. Since I won't be keeping these, I've decided to only upgrade the parts in the crossover and keep its stock design. Not sure that I could even recoup doing a cabinet refinish, so I will most likely end up selling them as is... They do sing quite well... |
Thanks for the vote of confidence Isochronism. To really improve these, it would take a crossover re design, I haven't run curves, but my instincts are that crossover point would move up to 600 or so and slopes would change from 12/12 to 12/18 to improve phasing. Then if I'm going to do that, might as well brace these cabinets. They really could use some re finishing.. easy enough. I could get lost in these and yes, they would be excellent. The bottom line is WAF won't go. Yes, I believe that I could over rule her and keep these, But my old body still functions and I'd like to keep an active (night)life. My current MTM's are very good and overall, I prefer them to the Altec's in their current form. These are very large and really could use a listening area larger than I have them in. I realize that some day, I'll kick myself for letting them go, but overall it my best call today. |
You guys have been great, I made another change, so I thought I'd give you an update. 1 of the dust caps was dented. I bought a matched pair. I was lower mass (weight) than the original, with the 416A driver having a QTS of around .27, I really did not want lower mass. The factory cone is not nearly as stiff as I would like, so I made a 50/50 mix of Latex and Wood glue. I put 2 thin coats over the entire cone including the dust cap. I estimate that I lost about .2 db of overall sensitivity from the driver... (decrease from 99.5 to 99.3 and raised QTS to around .3, I still need to re port the cabinet, but again, Improvement, lower midrange detail is as well as the blend of drivers is better. Next I will do some experimenting with changing the vent tuning and try to find some attractive way to dampen the horn. These are actually a surprise to me. These big dogs sound very, very nice. |
Thanks Gvasale, at least now, that link won't open for me. Don't know about a mid bass horn, there is a 15" woofer and tweeter (horn). I'm thinking about trying cutting to fit some self stick type materials and see how that works. I'll find something that works well. Plenty of ways to dampen the horn, mostly worried about the appearance since the horn is externally mounted. The cone mod mentioned in my last post was stiffening/dampening the woofer cone while replacing the dust caps. I hope to get your link to open later, thanks for all the suggestions.
Tim |
Thanks Ralph, dynamat is on my radar, years
Ago I had a store and we used this in doors
And even trunks, I'm also thinking about possibly looking at some self stick flooring materials. If I can find one pliable enough
and cut carefully, it could look decent. |
Gvasale, I wasn't thinking woofer's horn load itself, yes, cabinet bracing on this speaker is poor, just a few in key area's will go along way.
Thank you, Tim |
@kipduff
Hi Kip,
If you are going to do a simple parts upgrade, measure the inductors, If they measure fine, just use them. If you are going to replace a diaphragm, if you can afford it, I’d replace them both. They could sound different from the originals and keeping them matched is important. Over time, I’ve played with alot of caps, for this project, I would replace C1 & C2 both with Jantzen Superior Z. Replace the resistors with Mills 12 watt non inductive. Overall these changes will be a true transformation to these speakers. |
Hi Kip,
Not sure of your budget....If no budget, yes, get the Jantzen superior z in a 12mfd and a 6.8mfd.....
If budget is an issue, take a look at Solen PPE caps... the other Solens are ok too, but I clearly Prefer the PPE, then get a Russian K71 polystyrene from Ebay.... this combination is very satisfying after a good break in...I have used the Solen, the K71 and Jantzen's all 3 paralleled together with very good results....
The K71 is very limited in its size availability.... they come in 1.0mfd.... 1.5mfd..... 5mfd and 10mfd. You could use 10mfd of the styrenes and 12mics of another cap with very good results... I don't care for ANY of the other Russian caps on speakers.
There are certainly other good caps, but these are all very high bang for the buck, Tim
|
Not sure that you read the entire thread... I did these around 5 years ago and sorry, I dig into so many speakers that I don't take photo's. As I mentioned in the thread, after the crossovers were built, they had some sort of material poured on them and it dried encasing them. I chipped it away to uncover all of the parts, they came clean easy enough and the crossovers were then easy to modify. I hope this helps, Tim |
