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Pete B

Small Advent Rebuild by Pete Basel

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I made a trade with a friend for a pair of Small Advents.

Both have green tweeters with the small 2.5" square magnets and the 12/8uF 1R crossover.

First system has a tweeter dated Feb 1, 1973 that measures 2.92 ohms RDC, and

a woofer that measures 3.38 ohms.  Tweeter inductor measures .39 mH/1.19 ohms, resistor

reads .91 ohms.

Both were recapped by the friend with poly film caps.

The woofers were over driven with the VC formers being bent so that a rebuild was

required as detailed here:

http://audiokarma.org/forums/index.php?threads/small-advent-woofer-vc-dimensions-solvent-to-break-glue.819443/

 

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One woofer is back together, keep in mind that the previous owner refoamed glueing the foam

incorrectly to the front of the cone.

I'm listening to the one finished system with a high current amp that will do 250W at 4 ohms,

grilles on.

I find them to be very forward and nearly spitty sounding, lots of strange sibilance on vocals,

the midrange coloration adds a strange character to everything, piano, horns, etc.  BSC helps

a lot, I'm using 4 db and it is much better.

I was very careful about rebuilding the incorrectly refoamed woofer and I'm finding that while

there is a LOT of throw, it bottoms very easily with dynamic, punchy bass lines.  I should say

very easily when played LOUD.  While I like to always have headroom in a power amp, this 

might be a case where the amp running out of steam to avoid bottoming the woofer would help.

It is also possible that refoaming with the foam correctly glued to the back of the cone might

help a bit.

Junior Wells  "Use Me" on Telarc is a real torture track when turned up:

https://www.youtube.com/watch?v=yTWa--9oNg0

There seems to be no comression on that track and it does much better on all the bass heavy

tracks on the Burmeister II CD.  It even does reasonably well on the C1 (32.7 Hz) organ note 

on track 7.

Given that the woofers were damaged, my guess at this point is that the tweeter is also 

damaged, however the distortion is nothing like I've ever heard as a buzz or weak/no output.

It might be a buzz at an unusual 5KHz or something like that, I should try test tones on the

tweeter while listening for distortion.  This tweeter does not have ferrofluid so no issue there.

I find it very hard to believe that Kloss once said this was his favorite speaker.

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Pete, something doesn't seem right here.  I have a pair of recapped, refoamed smaller Advents that get a lot of use, and they are pretty good speakers.  Nothing at all as you describe.

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Running a swept sine wave into it, surprising how much output there is at 32 Hz, moving
on up the tweeter gets buzzy sounding around 1400 Hz, then cleans up but then worse at
3385 Hz this is with 4.25 V RMS in which is a decent amount of power.
Tried flexing the tweeter masonite with the 3385 Hz tone and it made little difference even
though it seems a bit loose.
Tone cleans up again but then sounds very nasty like a buzzer around 4055 Hz, no change
with the masonite. Cleaned up then buzz came back at 4400, 5190, 5280, 5340, stopped
at 6500 Hz. I'm sure that this distortion is the source of the edgy, spitty, strident sound.
I'm going to guess that some of the voice coil windings are loose, but who knows?
I know what the Advent tweeter sounds like and this is not right.

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Just swapped the other tweeter in and it sounds like a normal Advent.
I can really enjoy these with 4 dB of baffle step and the bass is really impressive.

Anyone have a green tweeter with the small magnet?

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My speakers also have the green tweeters, did they come in different magnet sizes?  Date stamp on one is 1972, not sure what the other is dated, as one of them was a replacement.

Now that I re-read your post, I think you are asking that you want a replacement tweeter?

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Yes, just to get both sides working but also to see if the one better one might be slightly damaged.

Do you have one for sale?

I read somewhere that in the early years the green tweeters were small magnet but that later

green ones were made with large magnets.  I think, probably, for parts commonality they went

to the same tweeter in Large and Small versions.

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If the tweeter has a 1972 date on it, the magnet is a small one (2.5" square. not 3" square.). Any green tweeter from about 1975 on has to be checked for magnet size as Advent used up the green cones, even on large magnet tweeters.

Doug

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On ‎5‎/‎4‎/‎2018 at 5:28 PM, Pete B said:

One woofer is back together, keep in mind that the previous owner refoamed glueing the foam

incorrectly to the front of the cone.

I'm listening to the one finished system with a high current amp that will do 250W at 4 ohms,

grilles on.

I find them to be very forward and nearly spitty sounding, lots of strange sibilance on vocals,

the midrange coloration adds a strange character to everything, piano, horns, etc.  BSC helps

a lot, I'm using 4 db and it is much better.

<snip>

I find it very hard to believe that Kloss once said this was his favorite speaker.

I picked up a pair of these a few years back - one of my favorite 2-ways. I use it connected to an AVR and have a "switching box" to test various pairs in A-B tests or just pick and choose which ones I want running as the stereo pair. Anyway, I can understand why Kloss would have liked these; the soundstage and imaging is wonderful, always have to stop and re-determine which pair of speakers are the active stereo pair when the Smaller Advents are at play as they sound so great and disappear in the room.

All that said, now I have to go check and see how the previous owner re-foamed the woofers !!

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How many watts are you running?

Playing more normal source material and going a bit easier on the volume they are

doing pretty well.  I put them against the wall and then they seem to need a bit less

BSC 3dB seems about right.

I would like to get a pair of woofers to refoam myself with correct foam installed correctly.

I'm only listening to one but it is really impressive that it plays lower, far lower, then other

much larger bookshelf speakers.

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On 5/13/2018 at 8:18 PM, Pete B said:

Do you have one for sale?

Sorry, but I don't have any spares.

My smaller Advents are sitting in the same location where I had OLA's.  However the electronics have changed so i can't  do an exact apples/apples comparison.  I very much liked the OLA's, but in this space I prefer the smaller Advents, they don't call any attention to themselves, they seem smoother.  They play nice at low and high volumes.  In some ways they bring to mind my mid-90's NHT super ones; they don't do anything wrong.  I'm sure there are better speakers, but for me, they work as very pleasant companions.

Good luck with replacement drivers and bringing the speakers back to life, I think you'll find it worth it.

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Checked both woofers; foam is behind the edge of the paper cone. I assume the previous owner/flipper knew what he was doing as the spitwad dustcaps are unmolested. It has green tweets but I never opened these up to see any information or to re-cap as they work fine for now.

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