Modifying(upgrade) ProAc Studio 200?

[jheoaustin]

Hello.

I wanted to get experts' opinions on something I'd like to do. I have been using ProAc Studio 200 since early 1995, and finally found that the foam edges of 18W8542 woofers were all cracked. I looked for some info. to replace or fix them, and found that options were $15/pc kit or $65/pc driver repair, or $2xx/pc driver replacement(could be cheaper, I guess). That just made me think that putting $300 or $900 to worry about the same thing 9 year later is not favorite. So, I changed my mind to replace all drivers and crossovers to make a new speakers. As I am poor at tools and woodwork skills, I just want to replace drivers which can be mounted in place of 18W8542 and seas 1" soft dome tweeter. I also believe I will have to redesign crossover for driver changes, but not sure even with redesign, I can get the right alignment of bass with existing enclosure and new drivers. But I want to try anyway.

Could you advise me whether this is feasible or not, which drivers to use, how to design crossovers, and internal dimension of Studio 200 enclosure, etc.?

I am looking forward to your kind advices.

[jheoaustin]

Can anybody help me??

[sreten]

Replacing the surrounds is the best option by far , even if you
have to do it every ten years or so, but it should be the case
the new surrounds are more resilient than the originals.

If the surrounds are not too far gone repairing the cracks
and a coating of proper rubber glue can help matters.

sreten.

[jheoaustin]

Sreten,

Thank you for your kind reply. You think the feasibility of using different drivers from originals are pretty low. Am I right? If yes, is it because it's theoretically impossible? Or too high design/part cost? I am looking forward to your further advice.

[tktran]

If you use different drivers then 95% chance you'll need a different crossover. Most likely you will a different port tuning too.

Which really means you're building a speaker from scratch, and by limiting yourself to that box will make it more difficult for woofer selection.

To really design a loudspeaker you need to mount a woofer in your intended enclosure, do some measurements and then crossover modelling. Install tweeter, measure some more and do some tweaking.

Doing it by math never really works properly.

Replacing/repairing the surround is often done and iIf you're happy with the sound of your speakers replacing the foam surround would be cheapest option

[jheoaustin]

tktran,

Thank you for your informative reply. So, in example if I replace the 2 18W8542s to 2 18W8545s, I will probably get as high performance as the Studio 200 enclosure with 18W8545 can get, but it CANNOT be as good as original Studio 200. Am I understanding it correctly? Could you also tell me how successful this kind of modification(modifying crossovers, too) be NORMALLY?

Another question is, how much can a fine-tunable electronic or digital equalizer can help this problem. This may be too vague a question, but I would appreciate any answer to this stupid question.

[diamdiam]

Hello,

Well to answer your question... no it won't sound the same at all. If you look at the specs/the data sheet you'll notice that they are different. These numbers are the Thiel Small parameters, the characteristics of the speaker. Now if you were to plug those numbers in to a program like WinISD, which is free, you'll see that the response curve would be different. It would probably sound completely different, and I am guessing worse. Like tktran said, you'll be doing a lot of work for any changes you make, which could be fun, but you are basically redesigning the speaker. I agree with what the others said, in that you should just repair the surround. Too bad you didn't post 2 weeks ago, I just sold a pair of 8542s for pretty cheap. They are really good drivers, so it's definitely worth repairing. If you don't like your studios you should repair them and ebay them and get into the diy hobby with a speaker kit or something. You should head over to the madisound.com forum if you have more speaker questions.

Diamdiam

[jheoaustin]

Diamdiam,

Thank you for your advice. I am now thinking of both ways, to repair, or to modify. One thing bothering me in repair way is that no genuine 8542 surround fix kit is known available. Do you know of anything like it? I contacted Meniscus audio for this, but they told me that the new surround will look thinner than the original. That may change the parameter of the driver too, I am afraid.

[diamdiam]

jheo,

that's a good question. i'm not sure what the answer is. in vance dickason's book there's a section on the mechanics of speaker parts. he shows that the material (foam, rubber and some new material) of the surround does change the parameters of the speaker. i don't know how audible it is though. the foam wil change the characteristics, but i don't know how significant it'll be. since it is fairly inexpensive, i would just get a kit and give it a try and hopefully the changes would be inaudible. i think if it is audible, only those few with trained and/or gifted ears could tell. i've read a few posts from people who've had repairs on old speakers and they didn't seem to be concerned with it. there's a few people over at the madisound forum that have done refoaming, so they'll have better knowledge and advice than me. good luck.

[diamdiam]

btw,
i found this online picture tutorial on how to refoam
http://www.decware.com/surround.htm