Pete B

@fedeleluigi There are several posts in this thread with the AR-9 xo schematic, is that one redrawn, and the one you are looking for an original from AR? I can look on my 10 year old computer where I probably downloaded it. On the other hand if the redrawn one is easier to read I might have just kept that one.

There's a good chance that they changed the spider also and rarely are they loose enough, good that you got the correct woofers - enjoy!

What model tweeter is in the XL, it is different from the non-XL version. Madisound might have a suggestion, they did for the non version.

@brianw Did you ever get plates made for a replacement tweeter? Sorry, got distracted with other projects and never posted the AR9 tweeter measurements. Both of my tweeters measured fine with an ohm meter. The foam gaskets were hanging off the back and stuck to the face plate in a few spots. I pulled them off and now on tweeter measures open circuit, perhaps there was glue on the lead in wire - don't know for sure. Anyway, here's more on the 3D printer that I've been using:

The YouTube person who complained about stringing got a lot of comments from other users who pointed out that one free "slicer" program works best with the Ender printers and that's what I use. No problems with stringing at all. I began to have trouble with the first layer sticking to the bed after about 50 prints. The Ender printers have a unique sandpaper like finish on the print bed, other people print on a smooth surface, some even use glass for flatness. One of the first things you'll learn when printing on smooth beds is that you need to help the first layer stick, many use glue stick, some use hair spray. I did not need anything for the first 50 prints or so and I've come to the conclusion that some of the rough surface has worn off so now I use glue stick and it works perfectly again.

Ah okay, thanks Roy good to see you on here, all the best!

Burnt FF causes diminished output and/or a rise in the moving systems resonant frequency. Where did you get that replacement center dome? I have a working NLA tweeter with a smashed dome. I agree that if you cut the dome off, you can certainly add the FF inside the VC, and if a tiny hole was cut into the VC former a needle injector could be used to put some FF on the outside where it is really needed. The other issue is how to remove the old FF? I wonder if those glued on center domes have the same response as the originals.

@Rick U PM message sent to you.

Bump, has anyone removed a tweeter for transplant? Also, does anyone know if there were any changes to the shape from the early AR3a to the last version? Pete

Very sorry to hear this, he helped me several times by pointing out literature in the library. He was far too young. RIP Robert Pete Basel

I tried to open them up here without much success. Is there a materials person who might know how the paper could be treated to make it less brittle? Or was it designed to be stiff and brittle from the start? https://audiokarma.org/forums/index.php?threads/disassembling-new-large-advent-nla-tweeters.953989/

I'm a bit late here but very nice work. That is a very low Fc of 40.5 Hz with just the right Qtc. I documented the crossovers and listed the NLA woofer inductor with a much lower value than the OLA which has the powdered iron core inductor: http://baselaudiolab.com/ADVENT_LA_XO.html

@Giorgio AR Those are nice pictures of the woofers. Does anyone know the correct part number for the AR-6 woofer? There is mention on here that the Xmax was quite high, higher than the other 8" woofers: Also was there a ceramic magnet version of the AR-6 woofer?

I would guess that it can be changed but it would not be an easy job. I have a blown NLA tweeter that I believe was driven so hard that the insulation broke down and the voice coil shorted, then the current went way up and the red donut part of the cone was burnt brown under the tinsel lead in wire. I want to take a look inside and the red paper lip at the outer edge is already lifted about 1/3 of the way around. Not sure what to use to release the rest of the glue. Acetone or MEK perhaps.

This is in the library as multiple .jpg s, does anyone have it in .pdf? I seem to remember seeing it years ago. It mentions measuring the DC resistance of the tweeter and tweeter inductors to test for burnout.

Here's 18 TPI Irish Linen: https://www.123stitch.com/m/18-Count-Linen-style-Cross-Stitch-Fabric Discussed many years ago in this thread: https://community.classicspeakerpages.net/topic/2884-advent-large-grillcloth-restorationreplacement/?tab=comments#comment-67500

I thought that someone found a source for very similar 16 count grille cloth. I don't remember where it was mentioned. There's 12 and 13 TPI here and they look close buy maybe not in real life: https://dorrmillstore.com/index.php/site/products/category/foundation_cloth/17

You can try suction with a hose of the right diameter.

Is boiled linseed oil usually that dark, or does it come in different tints?

I'm aware t hat the original material cracked, but how do you get the tweeter guts out to glue into the new piece? Solvent? Heat? Crack it off? Anyone have the .stl file?

Enter 40 uf and 1.37 mH into this calculator, and you'll find that they resonate at 680 Hz which is probably the fundamental resonance of the UMR: https://www.omnicalculator.com/physics/resonant-frequency-LC The L and C reactance cancel each other at resonance and you have a short (ideally) with a series resonance circuit or RDC of the L plus ESR of the cap at that frequency plus the 6 ohms in series. Call it 7 ohms which is probably the amount required to flatten the impedance, they might over or under compensate to shape the response curve as required. Note then that the 24 uF series cap forms a first order network to the UMD, which does not provide much attenuation at low frequency. I suppose that they get away with it due to the higher crossover frequency as compared to the AR-3a/AR-11. Is it correct that all of the drivers are in phase?

Sorry to be so late here updating Mine is also from B-A (something like Burnstein Applebee) without the electronics. I'd like to sell this unit for parts if anyone is interested.

The "fan thing" is a heatsink, does it move with the cone? I'd guess that it is thermally connected to the voice coil.

We can learn a lot by what is common and not, between them all: 1. 41-42 Hz closed box resonance (Fc) which is roughly low E on a bass guitar 2. Closed box Q (Qtc) of about .8 - .85 ish which makes the half space response less than 3 dB down at Fc 3. The OLA and NLA had only about 3mm theoretically linear Xmax (one way) and a huge Xmech of about 13mm. We can compute an overload headroom as 20 log(13/3) = 12.7 dB of overload headroom. 4. The OLA voice coil former is a very rugged brass/bronze looking type. The later versions had and aluminum type. 5. The tweeters are just OK, the NLA tweeter has an input impedance that is too low. If they were voiced less hot with more resistance in series then they might work good enough. 6. The Jensen design keeps the Advent bass (42 ish Fc and .8 ish Qtc, not sure if Xmax changed) but the crossover voicing is not as good IMO. 7. They all need baffle step compensation to sound truly HiFi IMO.

Would you please tell us where you got the new domes in case anyone wants to repair an AR tweeter in the same way?