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Recapping Large Advents


DON

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Can the crossover of the Large Advents be removed or do you just work through the woofer opening? I have a pair that probably need recapping and I've never seen a crossover out of the speaker. Thanks.

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It's best to work thru the woofer hole to recap your speakers. Those xover boards are usually glued and stapled in and are very hard to remove and re-install in the correct position.

Thanks Carlspeak. Seems like that would be very crowded. Can a man get both hands through the woofer hole and solder? I'll just have to take a woofer out and see for myself :D :D Thank you. Don

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Thanks Carlspeak. Seems like that would be very crowded. Can a man get both hands through the woofer hole and solder? I'll just have to take a woofer out and see for myself :D :D Thank you. Don

As long as you don't have arms like Arnold Swartzenegger, you should be okay. I've done many of them that way.

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As long as you don't have arms like Arnold Swartzenegger, you should be okay. I've done many of them that way.

I have a pair that were recently recapped and a pair that are all original. I had a chance to compare them today and there is a huge difference. The ones with new caps have a subdued sound in the upper midrange and treble. The originals have a very open sound with a fairly smooth upper midrange and treble. Just this side of harsh but preferable to the ones with the new caps. Maybe they'll improve after they have a few more hours on them. The bass on both is very deep but not boomy.

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  • 3 weeks later...

That's why I believe in leaving the cotton pickin' capacitors alone if they measure OK instead of willy-nilly replacing them.

There is this assumption among enthusiasts these days that replacing the caps. with "audiophile" caps. will automatically result in a glorious improvement in sound when, if you think about it, the speakers were originally voiced with the original type caps. in them.

I have 5 pairs of original Advents and, when I bought each pair, I tested the caps. and every single one of them measured within spec. so they remain in place. And the speakers sound wonderful.

Are your two pair otherwise identical? Because other differences could account for the rather large difference in sound too.

But I still cringe every time I read, "Recap those Advents too." The assumption being that the capacitors are automatically bad just because they have some years behind them.

Oh, and there are no capacitors involved in the woofer circuit so it won't matter what kind are in there regarding bass response. There is only an inductor in series with the woofer.

Doug

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That's why I believe in leaving the cotton pickin' capacitors alone if they measure OK instead of willy-nilly replacing them.

There is this assumption among enthusiasts these days that replacing the caps. with "audiophile" caps. will automatically result in a glorious improvement in sound when, if you think about it, the speakers were originally voiced with the original type caps. in them.

I have 5 pairs of original Advents and, when I bought each pair, I tested the caps. and every single one of them measured within spec. so they remain in place. And the speakers sound wonderful.

Are your two pair otherwise identical? Because other differences could account for the rather large difference in sound too.

But I still cringe every time I read, "Recap those Advents too." The assumption being that the capacitors are automatically bad just because they have some years behind them.

Oh, and there are no capacitors involved in the woofer circuit so it won't matter what kind are in there regarding bass response. There is only an inductor in series with the woofer.

Doug

The pair that have been recapped and refoamed have the masonite flange. The major difference is that the highs are more subdued on the recapped ones and they are not as loud with the same input as the others. The ones that have not been recapped sound very good. I play the new caps about 6hrs. everyday (repeat on my cd player) they're in another room and can't be heard. Maybe they'll improve. I can't see well enough to se the values of the caps but I'm sure I can find it. Thanks again Doug you've helped a lot.

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You say that the recapped ones have the masonite flange but then you say nothing about the other pair. Is it possible that the other pair is New Large Advents, which are a very different animal (much brighter)?

;e

The pair that have been recapped and refoamed have the masonite flange. The major difference is that the highs are more subdued on the recapped ones and they are not as loud with the same input as the others. The ones that have not been recapped sound very good. I play the new caps about 6hrs. everyday (repeat on my cd player) they're in another room and can't be heard. Maybe they'll improve. I can't see well enough to se the values of the caps but I'm sure I can find it. Thanks again Doug you've helped a lot.

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You are doing an uncontrolled test, unknown drivers, caps, designs.

If you do a controlled test you will find that cap type does not

make any significant difference as long as they are not junk:

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=2790&st=0&p=66870&hl=+capacitor%20+axon%20+poly&fromsearch=1entry66870

Old caps should be changed, Military uses 10 year shelf life.

If you push them hard at all there is a chance you will blow

the tweeters if your old caps are or become leaky.

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Your pictures and diagrams were helpful to me when I recently re-capped a pair of New Large Advents. As an experiment, I used slightly lower than the 13mfd value of the originals (I think I use 10s or 11s) to see if I could tame the brightness just a touch and maybe introduce a very slight (1 db or so over about 4 notes, if one does the math) BBC dip. To be honest, they sounded maybe a touch smoother, but the brightness was still there. If there was a reduction, it was subtle. Might an extra 1 or 2 ohm resistor in series with each tweeter help? L-pads are too complicated for me. We still don't know if the original poster has identical pairs of speakers (except for the capacitors) or if he's comparing original and New Large Advents.

-----

I'm the author of this page - might help:

http://baselaudiolab.com/ADVENT_LA_XO.html

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Have you tried them (NLAs) in the decrease position?

This adds 1.5 ohms in series.

The tweeter is about 3 ohms with a fixed 1 ohm resistor

in series to bring it up to 4 or 5.5 in the decrease

position.

You would want to scale down the cap but the same amount

that you scale up the resistance if you add much more

in. A few ohms is probably fine since you already

lowered the cap but you could take the cap down even

more to 8 uF.

Any interest in trying the BSC circuit, it completely

transforms them?

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As long as we're on the subject of recapping NLA's, I thought I'd add some test data on an original Unicom 13 uF 50V NPE and three other, modern film type caps.

WT2 arbscans were run on four 13 uF capacitors (visit here for more info on arbscans http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6330). I removed the original, Unicom 13 uF 50 V NPE cap and orderd a 13 uF Auricap cap direct from Audience (customer request). I also happened to have in stock an Erse Pulse X and a Carli 12 uF paralleled with a Carli 1 uF cap.

Below are the deviation from 13 uF target and ESR performance charts.

Here is some additional test data which is also interesting. The following stats were extracted from the 31 data points taken from each scan.

Coeficient of variation (measure of spread of data) of the capacitance measurement

Unicom=3.98%, Erse=0.88%, Carli=0.53%, Auricap=1.74%

Phase angle coeficient of Variation

Unicom=2.34%, Erse=1.1%, Carli=1.06%, Auricap=0.64%

Phase angle mean deviation from ideal -90 deg:

Unicom=3.64%, Erse=0.64%, Carli=0.76%, Auricap=0.29%

Conclusions:

The vintage Unicom NPE obviously did not have good performance across the frequency spectrum as evidenced by the above stats and charts below. The 3 film caps all had low ESR as one would expect. Somewhat suprisingly, the low cost Erse and Carli caps fared best in the bottom chart. The Auricap maxed out at it's printed 10% tol limit at +1.3 uF at 20 kHz. OTOH, the Auricap cap had superior phase angle test results.

ESRperfof13ufcaps.jpg

chart13uFdevfromtrget.jpg

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I always run NLAs in the decrease position. And I turn the treble control down a bit on my pre-. I'm mostly into refinishing the cabinets, so I'm lazy when it comes to working inside the cabinets. But maybe I'll try some 8mfd Daytons and add 2 ohm resisitors in series with the tweets in my remaining pair. I like the clarity of NLAs' highs; I just find them a bit bright. Thanks for the suggestion, by the way!

-----

Have you tried them (NLAs) in the decrease position?

This adds 1.5 ohms in series.

The tweeter is about 3 ohms with a fixed 1 ohm resistor

in series to bring it up to 4 or 5.5 in the decrease

position.

You would want to scale down the cap but the same amount

that you scale up the resistance if you add much more

in. A few ohms is probably fine since you already

lowered the cap but you could take the cap down even

more to 8 uF.

Any interest in trying the BSC circuit, it completely

transforms them?

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I always run NLAs in the decrease position. And I turn the treble control down a bit on my pre-. I'm mostly into refinishing the cabinets, so I'm lazy when it comes to working inside the cabinets. But maybe I'll try some 8mfd Daytons and add 2 ohm resisitors in series with the tweets in my remaining pair. I like the clarity of NLAs' highs; I just find them a bit bright. Thanks for the suggestion, by the way!

-----

I suggest you recap with non-polar electrolytics to maintain the original ESR level as close as possible in addition to the 2 ohm resistors in series you plan to install. Using a film cap will just kill the original NPE ESR and, in effect, you'll be be taking one step backwards before going two forwards to tame the brightness effectively.

I'm not sure if 13 uF NPE caps are available any longer. Parts Exp. does have 12's and 1's you can parallel to get 13.

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I suggest you recap with non-polar electrolytics to maintain the original ESR level as close as possible in addition to the 2 ohm resistors in series you plan to install. Using a film cap will just kill the original NPE ESR and, in effect, you'll be be taking one step backwards before going two forwards to tame the brightness effectively.

I'm not sure if 13 uF NPE caps are available any longer. Parts Exp. does have 12's and 1's you can parallel to get 13.

I did the experiment in the link that I provided.

If you go with film and you think 2 ohms is about

right with the Nps, just add another .5 ohms to

make up for ESR. So use 2.5 or 3 ohms instead.

It is VERY hard to hear the .5 ohm difference.

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I always run NLAs in the decrease position. And I turn the treble control down a bit on my pre-. I'm mostly into refinishing the cabinets, so I'm lazy when it comes to working inside the cabinets. But maybe I'll try some 8mfd Daytons and add 2 ohm resisitors in series with the tweets in my remaining pair. I like the clarity of NLAs' highs; I just find them a bit bright. Thanks for the suggestion, by the way!

-----

Not sure if you are aware, but the OLA used an inductor for

The decrease position which significantly rolls off the high

end extension - it is essentially useless.

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I went back to the Advent Crossover link but couldn't find reference to the experiment you mentioned. Maybe I was looking in the wrong place.

----

I did the experiment in the link that I provided.

If you go with film and you think 2 ohms is about

right with the Nps, just add another .5 ohms to

make up for ESR. So use 2.5 or 3 ohms instead.

It is VERY hard to hear the .5 ohm difference.

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No, I didn't know that. Aren't inductors low pass filters? Did they choose a value that allows SOME highs to come through?

-----

Not sure if you are aware, but the OLA used an inductor for

The decrease position which significantly rolls off the high

end extension - it is essentially useless.

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Don: Which Advent do YOU have? OLA's or NLA's?

This thread seems to be bouncing back and forth between the two.

The OLA does have inductor coils that interact with the tweeter as Pete points out.

The NLA has only 1 inductor coil in series with the woofer and has no direct effect on the tweeter crossover slope.

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Don: Which Advent do YOU have? OLA's or NLA's?

This thread seems to be bouncing back and forth between the two.

The OLA does have inductor coils that interact with the tweeter as Pete points out.

The NLA has only 1 inductor coil in series with the woofer and has no direct effect on the tweeter crossover slope.

He has NLA's I was just commenting so that others don't try it with the OLAs.

Seems like the -3 dB is probably 7 to 10 KHz - better than a telephone at least!

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I went back to the Advent Crossover link but couldn't find reference to the experiment you mentioned. Maybe I was looking in the wrong place.

----

This is a link to a thread where I compare the original NP caps to several Poly film caps, it was VERY difficult to hear any difference:

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=2790&st=0&p=66870&hl=+capacitor%20+axon%20+poly&fromsearch=1entry66870

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Have you tried them (NLAs) in the decrease position?

This adds 1.5 ohms in series.

The tweeter is about 3 ohms with a fixed 1 ohm resistor

in series to bring it up to 4 or 5.5 in the decrease

position.

You would want to scale down the cap but the same amount

that you scale up the resistance if you add much more

in. A few ohms is probably fine since you already

lowered the cap but you could take the cap down even

more to 8 uF.

Any interest in trying the BSC circuit, it completely

transforms them?

Hi!

I would like to borrow the BSC circuit once again.

I have been working on my Advent setup and have it to the point where they sound very good.

I have fiddled around with the placement and also have found a couple of amps which work very well with them. An Acurus A250 and a 175wpc Carver.

If you let me know the shipping, I will send a payment via money order or Paypal.

It is a pleasure to be associated with the people on this forum. It's such a civil and informative environment.

Once again, thank you very much (whether you send the unit or not).

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What IS the BSC circuit? Can someone post a link so I can read up on it? Thanks for the info about different caps. I did read that. Not surprised differences are subtle.

-----

Hi!

I would like to borrow the BSC circuit once again.

I have been working on my Advent setup and have it to the point where they sound very good.

I have fiddled around with the placement and also have found a couple of amps which work very well with them. An Acurus A250 and a 175wpc Carver.

If you let me know the shipping, I will send a payment via money order or Paypal.

It is a pleasure to be associated with the people on this forum. It's such a civil and informative environment.

Once again, thank you very much (whether you send the unit or not).

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Hi!

I would like to borrow the BSC circuit once again.

I have been working on my Advent setup and have it to the point where they sound very good.

I have fiddled around with the placement and also have found a couple of amps which work very well with them. An Acurus A250 and a 175wpc Carver.

If you let me know the shipping, I will send a payment via money order or Paypal.

It is a pleasure to be associated with the people on this forum. It's such a civil and informative environment.

Once again, thank you very much (whether you send the unit or not).

Thanks Stan, just PM me your mailing address, no need to pay

me anything it is just a buck or so to mail it.

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