[pault1]

For some reason the forum does not allow me to do a key word search.  I read back through multiple years of post titles and didn't see what I was looking for, so here goes:
I've a pair of Tower II's which I was privileged to have Brian set up for me once I constructed them from their kit.  I'm sure that dates these back to the early to mid 1990's or so.  Anyway, when getting ready to try them out in a new house I thought to check out the PR's and one of them has foam rot.  They aren't in a huge room and I'm using a 626 as center channel so there's generally plenty of bass, and it was a very gradual loss so wasn't terribly obvious.  Also I'm not the best of the golden ears, I just know what I like.  Which is VMPS of course.

But I note that the main front panel drivers surrounds are: lower - butyl rubber, and upper - foam type surround.  Thinking of this I was surprised that the PR is a foam type.  Maybe because it isn't driven, it would be expected to have less excursion than the low frequency woofer?  Is that even a good guess as to the difference between the two types?

Anyway, is there a recommended kit for the new surrounds?  I have done the new surround deed on a friend's set of JBL's in the past, in addition to being the builder of these as noted, so shouldn't be any big skill issues.   While I am in there I will probably do the "vitrification" trick with wood glue that is detailed elsewhere on the forum.  Any assistance is gratefully appreciated!  Paul

[Evoke]

I wouldn't be concerned about the type of surround. There are different engineering reasons for a designers choice for various types of drivers. And FYI - PR's cab have immense excursion. I had old Dalhquists and Velodynes. I had them redone for me. While it can be done DIY - be prepared to be VERY patient, and it's critical you get the correct kit to do the job.


NOTE - after you complete the job, it will take some hours to break in the suspension. During that time the bass will come back to normal. There are a number of companies that sell kits - it helps to know the brand of the driver. Check with John Casler for more info that he may have. You can use generic foams. In the meantime, you can GOOGLE speaker surround repair. Here's are a few links: https://www.midwestspeakerrepair.com/product-category/speaker-repair-kits/      https://www.simplyspeakers.com/speaker-foam-repair-new-edge-it-kits.html

[rpw]

I second Simply Speakers, I have used them twice. I got the kits for 4 Dynaudio 8" drivers which was pretty easy to diy. I also sent four 5" metal drivers to them to refoam, great job and quick turnaround. Highly recommended.

Good Luck

[Stimpy]

A new CSS 12" passive radiator, should work, as an upgrade.  They were being recommended as replacements, and then left the market for a time.  But, CSS drivers appear to be back to normal availability.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://meniscusaudio.com/product/css-apr12/&ved=2ahUKEwjY3trxubfiAhXjmeAKHVV8B80QFjAAegQIARAB&usg=AOvVaw2ompB1IFu4idQie1NftQW9&cshid=1558813824197

Oh, I've used Simply Speaker foam too, without issue.  But, I like to also point people to Bill LeGall, at Millersound.  Bill is the best speaker repair guy in the country.

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.millersound.net/&ved=2ahUKEwikucecvbfiAhUvhOAKHcNxAeoQFjAcegQIBxAD&usg=AOvVaw0KCJBBTt8PnDCbgm4qlF7v&cshid=1558814696677

[Shear Bliss VMPS]

I second Stimpy, Miller Sound in PA. Bill LaGall is awesome, he did my ST/Rs years back.

[John Casler]

A new CSS 12" passive radiator, should work, as an upgrade.  They were being recommended as replacements, and then left the market for a time.  But, CSS drivers appear to be back to normal availability.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://meniscusaudio.com/product/css-apr12/&ved=2ahUKEwjY3trxubfiAhXjmeAKHVV8B80QFjAAegQIARAB&usg=AOvVaw2ompB1IFu4idQie1NftQW9&cshid=1558813824197

If you can afford it, the CSS will exceed the performance of even the BiG Bump Passive Radiators.

Not sure they will fit the cut-out, so you may have to surface mount, but since the PR is underneath that should not be a problem.

Just make sure and tighten the screws in a manner that does not pull the PR off center so you have no air gaps.

Properly mounted, they will give you a whole new speaker in the BASS.

The screw pattern should likely match up.

I would start with minimal washers like 3-5 and see how it sounds.

You can even get some putty and place it on the screw off cup to "fine tune/putty pinch" if you feel it necessary. or fun.

[pault1]

Thanks, did you mean that they were being recommended by Brian Cheney, or by others with VMPS speakers?

The washer system is easier looking than the Mor-Tite method but as they're the bottom-facing PR's it's about the same time investment to lay the speaker down, take the bottom apart and do the change. 

Paul

A new CSS 12" passive radiator, should work, as an upgrade.  They were being recommended as replacements, and then left the market for a time.  But, CSS drivers appear to be back to normal availability.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://meniscusaudio.com/product/css-apr12/&ved=2ahUKEwjY3trxubfiAhXjmeAKHVV8B80QFjAAegQIARAB&usg=AOvVaw2ompB1IFu4idQie1NftQW9&cshid=1558813824197

Oh, I've used Simply Speaker foam too, without issue.  But, I like to also point people to Bill LeGall, at Millersound.  Bill is the best speaker repair guy in the country.

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.millersound.net/&ved=2ahUKEwikucecvbfiAhUvhOAKHcNxAeoQFjAcegQIBxAD&usg=AOvVaw0KCJBBTt8PnDCbgm4qlF7v&cshid=1558814696677

[pault1]

I wouldn't be concerned about the type of surround. There are different engineering reasons for a designers choice for various types of drivers. And FYI - PR's cab have immense excursion. I had old Dalhquists and Velodynes. I had them redone for me. While it can be done DIY - be prepared to be VERY patient, and it's critical you get the correct kit to do the job.


NOTE - after you complete the job, it will take some hours to break in the suspension. During that time the bass will come back to normal. There are a number of companies that sell kits - it helps to know the brand of the driver. Check with John Casler for more info that he may have. You can use generic foams. In the meantime, you can GOOGLE speaker surround repair. Here's are a few links: https://www.midwestspeakerrepair.com/product-category/speaker-repair-kits/      https://www.simplyspeakers.com/speaker-foam-repair-new-edge-it-kits.html

Thanks for the comments.  But I am concerned about the type BECAUSE there are different engineering reasons etc. etc. and BC had presumably matched it up the way he thought best.

[pault1]

If you can afford it, the CSS will exceed the performance of even the BiG Bump Passive Radiators.

Not sure they will fit the cut-out, so you may have to surface mount, but since the PR is underneath that should not be a problem.

Just make sure and tighten the screws in a manner that does not pull the PR off center so you have no air gaps.

Properly mounted, they will give you a whole new speaker in the BASS.

The screw pattern should likely match up.

I would start with minimal washers like 3-5 and see how it sounds.

You can even get some putty and place it on the screw off cup to "fine tune/putty pinch" if you feel it necessary. or fun.

THank you for the feedback!  I'm not sure I want a 'whole new speaker'; BC tuned these for my room.  To be honest I'm not looking forward to the break-in and tuning process as I don't trust my ears to equal nor approach his.  But the CSS are not really expensive, only a small multiple of the repair kit cost, and would save me doing the labor for the glue upgrade.

Do you (or does anyone else here) know what the Fp of the original driver is?  The CSS state that the 12" has an Fp of 25 Hz but is tunable down to 6.9 Hz.  I would like to start in the range of what the original had, I would guess. The original product brochure (basic Tower II with no later upgrades) states that the -3dB point of the system is 22 Hz.

Side story - when you wrote "whole new speaker in the BASS", I flashed back to doing the speaker demo at BC's showroom in El Sobrante.  He asked me to bring some of my music for the demo, and one I had handed him was a Public Enemy CD - their front man, Chuck D, has a well known phrase where he declaims "BASS! How low can you go?"  But as soon as BC started up their track I requested, on a Krell that probably cost as much as my whole home system  an expression of distaste appeared on his face and he told me to call him when I was done with that artist as he exited the room.