Tweeter Replacement for rare ProAc Studio 2

I have a pair of ProAc Studio 2 that I replaced its original MB Quart Titanium tweeters 8 years ago with direct equivalent LPG 26T as one of the original wasn’t working.

A suggestion in my thread Unison Research Simply Italy to tame the bright Ti tweeters was to replace with soft textile dome tweeters. Aside from searching for a tweeter that physically fits in the opening, and knowing that there is ZERO information on those speakers on the net or from ProAc, what other aspects should I consider when selecting soft dome tweeters to preserve as much of the “ProAc” sound?

And if anyone has some technical specs on those speakers, I’d greatly appreciate it. Only site I found but doesn’t mention the Studio 2, which I’ve found one discerning difference I could see, they use a forward port made from different colour straws, yes drinking straws... Tannoy Woofers custom made for ProAc, and the sticker below.

My speakers with LPG 26t and custom made opening and straw forward port!



Some very similar ones but without the Straw based port and with the original MB Quart square Ti tweeters

 

A small history about those speakers. They were my late father in law first HiFi speakers from 1985. He loved them so much that when they moved houses, the speakers rode in his car and his wife in the moving truck he gave them around 5-7 years ago and I spend a weekend re finishing the wood and replacing the tweeters. He hasn’t used them for a long time and I was surprised with the great sound the first time I played them with my crappy Denon 3808CI .

Now I wonder if replacing the internal foam is relevant or not?

 

Contact Madisound, they might be able to find a fit.
www.madisoundspeakerstore.com/retrofits

 

That is very helpful ! Thank you But given that those speakers have no specs on them, I wonder how they may suggest something ?

At least they probably can provide something that fits physically and is soft dome, as I got tired of searching though tons of different models for the right dimensions.

 

ok i've been searching a lot for soft dome tweeters with similar physical dimensions and I think I need to again mod the opening, to fit some of the soft dome tweeters I've found:
- Scan-Speak D2608/9130
- Morel CAT 308

The Morel are ferro fluid cooled, and if I am not mistaken, the Thiel CS3.6 too, so I am probably gotta forego those ...

 

Unless you know the basic TS data for your tweeters, it's a shot in the dark finding a suitable replacement.

jeff

 

I actually do, I posted them in the first post, the current ones are LPG 26T. Though not sure how one could match a frequency response ... most other technical specs are easy to compare. Its obvious that changing the original design that used Ti tweeters to softer material will change the sound signature of the speakers, but if it improves it , why not ;-)

From a spec angle, I am trying to stay close to the resonant freq, of course using similar impedance and other obvious parameters.

 

Why? Simply because your current tweeters don't have ferrofluid?

 

No, because I read many things about liquid filled tweeters, from a longevity perspective ... The other speaker pair I got, Thiel CS3.6 had twice their tweeters replaced by my father in law. I may be wrong, but i am willing to change my mind However the Morel's resonant freq is way lower than the LPG 26.T (or the MB Quart originals), so unsure if that matters too.

 

I think most well designed ferrofluid-cooled tweeters can last a good 20+ years without issue. They do have advantages in terms of power handling.

The resonant freq shouldn't matter much as the crossover point will be much higher. This SEAS tweeter appears to be almost an exact fit but has lower nominal impedance:

SEAS Excel T25CF-001 (E0006) Tweeter

 

@Helom , thanks for the suggestions. I thought it’s best to stick with the same nominal impedance, SEAS is one company I haven’t explored fully, as most models I came across from them were 6 ohm.

 

Here's another potential candidate, considered to be a very natural smooth sounding tweeter: ScanSpeak Classic D2905/9500 1" Tweeter Textile Dome

I see Solen.ca has these in stock as well.

jeff

 

I ruled that one out as it is 6 ohm nominal while mine is 8 ohm... maybe I’ll just call Jean @ Solen and ask what works.

 

Good idea.

 

Perhaps the 8 ohm version of this unit? Unless I'm wrong the physical dimensions are pretty much identical.

Jeff

 

@vinylkid58 , Jean@Solen recommended this exact fit in 8ohm, Morel MDT32S, I am gonna go pick them up. Don’t know much about Morel but I trust Jean, he said the Morel is a softer sound than Scan-speak and are exact fit. He’s an amazing tech and also knows speakers in and out! (I never even knew that Solen supplied caps to Thiel back in the 90’s which he noticed on my CS3.6 crossover)

They are $128CDN each, average reasonable price... and @Helom yes they are Ferro-fluid cooled

 

Pretty awesome to have a resource like Jean@Solen so close.

jeff

 

I am so excited to try them! I spent more than an hour and a half talking to Jean there. They are 45mns away but worth the trip Every time. He also designs his own speakers. I listened to them very nice!

OT: I found out I can bring my old ProAc 2 and they can do a test (Thiele/small parameters) to characterize the speaker in case my woofer gives. It doesn’t exist anywhere in the world, it’s a Tannoy 1984 custom made for ProAc.

 

Ignorance is bliss...

Have I not known about that link and not contacted Madison, which BTW, they were awesome and speedy in their response, I wouldn’t have known that my current LPG 26T have different specs apparently.

The spec sheet that I found online seems to be an authentic spec doc from LPG indicates 90dB SPL, while Madison’s spec sheet indicates 92dB SPL, measured with MLSSA and looks more official than the former.

So which to trust? The 92dB tweeter recommended by Madison is also by Morel, Elite ET-338 and is $266 instead of $128 for MDT32S... @Helom , bcoz of you I learned all this, so it’s only fair you transfer me the difference I don’t mind paying more for the right tweeters... I wonder if my ear can tell the difference

 

Info like that could come in handy. Looks like a 6.5" woofer.

jeff

 

More like 8”, Or unless it’s the length from the woofer surround? But back to topic, now lost if I should install the MDT32S 90dB or bite the bullet and exchange for the more expensive 92dB, thoughts?

Big f’ing Magnet:

The forward port made from coloured straws !

 

I'd be inclined to stick with the MDT32s. I see no reason to spend more, unless you're building speakers from scratch.

jeff

 

Tweeters don't have meaningful Thiele-Small parameters. These parameters are for larger drivers. Tweeters have their own enclosure, which is the tweeter itself, and measurements such as Vas, the air volume equivalent to the mechanical compliance of the suspension, are meaningless.

There is nothing bad specifically about metal dome tweeters (I've got a pair four feet away); how they are implemented by the manufacturer matters more than the material.

That is a funny port indeed!

Straws or similar construction are often used for conditioning fluids into laminar flow. However, we are not straightening engine MAF sensor airflow, or laminarizing water for pretty water fountains. The point of a port is to act as part of the air spring of the enclosure. In 1984, at the dawn of wider dissemination of new ported enclosure research, but without Google to answer your questions, a speaker designer might have had a misplaced brainwave and combined two technologies that don't benefit each other.

In fact, the small hydraulic diameter of hundreds of little pipes means more turbulent flow within. A hundred little port noises instead of one big one.

Applying my limited brainpower, it seems the increased surface area of the straws can only increase the impedance, from the massively increased surface area. This means the port should act as a smaller area port, which lowers the frequency of the box tuning.

Without knowing much about either the current woofers or tweeters, or even the crossover design (although it can be reverse-engineered and modeled), it might be better to consider replacing all the drivers with ones known to synergize well. You'll also need a woofer that matches well with the enclosure volume and its porting.

 

@harby , thanks for your response. I know nothing about speaker design but I trust my Solen tech who’s been working and designing speakers for 30 years for himself. He had good things to say about ProAc’s use of straws for ports. It may have been that Mr Stewart Tyler was smoking up something but we will never know if I search the Internet, ProAc was well known for using straws in either forward or rear ports.

As for replacing all the drivers, for now I am doing a preventive measure by getting the speaker characterized using TSP and then replacing the current Ti tweeter which I have the technical specs with a textile one. Here’s a pic of the crossover, looks quite simple to reverse engineer.

If you look at the tweeter pics in the first post, you’ll barely notice that I actually nicely modded the previously square opening of the original MB Quart to a circular one to fit the LPG26T. If and when the woofer fails, I am sure I can repeat the process and keeping an OEM look.

 

Then why are they in the data sheet?

I've seen this before. Stuffing the port with straws is supposed to push the box alignment more towards "aperiodic", which would tend to flatten the impedance peak.

jeff