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Smaller Advents - Surround & Gasket Replacement?


thr33p4c

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I picked up a pair of Smaller Advents today with a lot of potential. All drivers functional. Woofers need foam. No badges but grills are pretty nice. Cabinets are near perfect.

I see some cheaper surround sets on eBay. Are these to be avoided? Any preference on suppliers for these?

I replaced all of the white foam gaskets on my KLH Fives with the Michael's craft foam method and they turned out great. Is there any advantage to putting new gaskets on the tweets in these cabinets?

What is the best solution for gasketing the woofers? There seems to be a gray duct seal like material currently in place but I think it has aged to junk.

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Congrats on obtaining some great speakers!

Not everybody has the odd size surrounds for the Smaller Advent but Rick Cobb does. He's also on ebay with "looneytune2001" as a screen name (I think that's how it's spelled - I always forget). Notice how big the roll on the suround is. Get ones like that and they should be very flexible, not rubbery like some of the cheap, thick ones.

The tweeter gaskets will be fine. They are pretty much degrade-proof.

Use Mortite rope caulk to seal the woofers. It's pretty much exactly what Advent used and it's handy because it's in a strip divided into thin "ropes" so you just peel off a single "rope" and apply that to the woofer frame before you install it onto the cabinet.

Good luck.

Doug

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Not many months ago, I purchased several foams for these same speakers from John at M-Sound (McPeak Sound Co.). The item number is SF-Adv9; description is 9" Advent surrounds; and price should be close to $8 per surround. Shipping costs are very reasonable. For sealing drivers, you already know about making new foam gaskets, but many use a duct seal "rope caulk" as another successful option.

Contact John at: msound@shentel.net

You've got the green tweeters - - - those seem to be the earlier version - - and I'd be interested to know the date stamps on your tweets and the configuration of your crossover.

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Yes, the green tweeters are from the introduction of the Smaller Advent in 1972 until sometime in 1975 when it seems Advent decided to use the same tweeter as in the original Advents and match the efficiency to the woofer with a crossover change rather than with the magnet size.

Doug

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Thank you for the quick response guys,

My XO is 12uF and 8uF w/ 2ohm Resistor. I think I will replace the caps w/ Polypropylenes. I have measured this type of cap in five different KLH Five boards varying in age and they all drift considerably. I will try to post the any dates I find on the Tweets. Everything has been packed up for the night. Woofers are stripped and ready for refoam. Ill post my progress.

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When looking on eBay I found a seller named myaudioaddiction. They and many others have the smaller advent surround listed as 9" w/ 7" speaker diameter. Mine measure at 7.5". In the myaudioaddiction listing they point this out and point me to another one of their kits. I see in VintageAR's listing that their Smaller Advent picture shows a Masonite rim on the basket like Dalquist does, and they describe the surround going on the back side of the cone. Mine have a black ring and attached to the top of the cone. Do I have an abnormal woofer? Maybe something from early production?

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It may looks like they are tucked under but I removed the surrounds a few hours ago and the surrounds were on top. I would have remembered having to scrape the bottom edge with a blade. I had to do that on some DQ-10s and its a pain. Diameter of my cone is 7 1/2"

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Guys, I have been talking with John at M Sound. He believes that the woofers were reconed at some point. Basically, he thinks that someone must have swapped the cone to a larger advent size cone so that they could use a particular surround. If this is true, whoever did the recone did an excellent job. Either way, I think John has a surround set that will get me up and running. I wonder if these will sound different, maybe even better with the extra surface area? Maybe worse with the extra weight and specs? Too bad I do not have another set to do an AB when I am done.

Any thoughts on John's conclusion?

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No expert here, but at least I can add observations and notes about my Advents. My pair with green tweeters have serial numbers 46XXX, and have date stamps on the metal tweeter plates from October 1972. I also have a 1975 pair with red tweeters that have similar date stamps, and I have sometimes seen date stamps on the backside of woofer magnets.

I typically trust John's advice and experience, but at first I thought that notion about cone replacements was unlikely. After a second look, however, I notice that the pattern of ribbed ridges on your woofer cone is different from both of my pairs (see pic attached), so in fact, John's diagnosis does appear very plausible.

Your crossover appears entirely original and fully identical to mine except for one thing: the cap values in mine are 8uf and 16uf, and it looks like one of your cap values may be 12uf. Not unlike other speaker models from this era, it appears there may have been several iterations of the Smaller Advent.

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Yes, after looking more closely at your pictures, I agree they have been reconed as the ribs are different and the surround is larger and has a larger roll than an original Smaller Advent woofer. Note how the cardboard ring (that is original) is almost completely covered by the surround on yours. Originally, the surround just overlaps the inner diameter of the cardboard ring.

It doesn't really matter, however. If John can get you a surround that will fit, they should still sound about the same as original. It's not that big a difference.

ra.ra, your two crossovers should be different from one another since, in 1972, the tweeters would still have had the smaller magnet and the 1975 pair, if they have orange tweeters, should have a larger magnet and resistor in there. I can't remember the values of capacitors except to say that Advetn did, I believe, change the values during production life. That was to compensate for the larger magnets.

Doug

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Also, there should never normally be any masonite on a Smaller Advent woofer. The ring is cardboard. The original Advent woofer has the masonite ring which was also used in the Dahlquist speaker. That's a nominal 10" woofer.

An original Smaller Advent woofer has the surround inner flange under the cone and the outer flange on top of the cardboard ring.

Doug

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I would agree that if you can get some foams that fit well, just re-foam and use the woofers with the cones you've got. Also, it has not been mentioned here yet, but there are many examples of those black/red caps (sometimes labeled Callins or Temple) having drifted far off spec after 40 years, and while I don't mean to encourage more re-cap madness, it just might be prudent to swap these out for simple new caps while you are in the process of restoring the speakers.

Doug, thanks for the note, and you are correct. As you can see in the pics attached, the crossovers in my two pairs are very similar but differ in the component (caps, resistors) values. The first pic shows the crossovers in the '72 green tweet pair (caps are 16uf and 8uf); and the second pic shows the '75 red/orange pair (caps are 8uf and 4uf). My point about several iterations of this model goes beyond this, however, since we see that the OP has different cap values in his green-tweet Advents than what I have found in mine. This difference has been confirmed elsewhere as well, and I'm not certain what may have instituted the x-o revision in the early (green) Smaller Advent.

[edit: the two taped caps are a 12uf and 4uf in parallel.]

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I have to place a PE order soon and was planning on picking up some of the PE Branded Polypropylenes to put in. 8uF is not very common so I plan to put in 8.2uF. I cannot remember where I read it but I remember someone saying 8.2 was fine in this application. The Parts Express caps are always really consistent. The Red/Black caps are junk after this long. I measured one of the 12uF in my Smaller Advents and it came out at like 15.5uF. I'm sure the other one will measure something dumb like 9uF. I have not entered into the recap or not recap debate but after seeing such outrageous drifted specs on this type specifically I would rather have my speaker sound as Henry Kloss designed it to sound as opposed unbalanced and inconsistent after 40 years of service.

We will see how my Smaller Advents sound with new cones, new surrounds, and new crossover components shortly. :)

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Finished these today. Here are some highlights...

The woofers were a bit of a pain but they worked out.

I got a surround kit from M Sound. It was tough to get exactly what I needed because of the modified cone. The surrounds hung over the edge a bit so I trimmed them down to the edge of the metal basket. The mortite worked wonderfully.

These sound surprisingly good. A bit bright but enjoyable overall. Just need some badges... I will probably PM Kent within a few days :)

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Nice job getting those back up and running. With all that goop removed, the crossover looks so much better than the original, and with the woofers, I think you did the best you can working with that odd-size cone diameter. Trimming the surround to fit inside the basket perimeter is a bit of an abnormal step, but certainly the right move to ensure a satisfactory glue seal. Very good work.

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