MC4/ Morel Supreme

Does this sound like a worthwhile project?
Interesting and expensive...
Do you change the xover?
http://www.morelhifi.com/products/pdf/Tweeters/ST/Specs sheet ST1048.pdf
http://www.clofis.nl/nl/seas/H0414 19TAFG.PDF
Faceplate and inside diameters are different. The res.freq is high for the SEAS. 1700Hz. What might not matter with/if a very high xover freq. on the Musical Fidelity MC4. Better with the Morel Fs=680Hz. If you can afford the money on those old speakers (?) I would go forward.:cool:
 
Hi Inductor and thanks for the reply.
It will be very useful to have the specs of the MC4 tweeter.
I know nothing about the technical aspects of what I intend but have a very knowledgable friend if I run into problems.
I have been speaking to Neil at Wilmslow Audio and he is very helpful too.
I am hoping to use the existing cross over.
I am a woodworker so adapting the baffle to acept a diferent tweeter should not be too dificult.
A better question to ask the forum may have been " Is changing the tweeter on a well designed commercially produced 'speaker likely to result in improvement?"
 
Very hit and miss project unless you plan to remeasure the drivers and redesign the crossover.
Try finding a tweeter with near identical specs (frequency response and impedance curve) for a straight swap. Check out the Vifa and Seas line. No need to spend more than 50 pounds per driver. Also think about upgrading the crossover components while you're at it.
 
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If it's the original MC-4 with the rectangular Elac metal dome tweeter I doubt there was any significant response shaping going on in the crossover. I must've had about the first of these in amateur hands for a DIY design. Assume about 90dB/ Watt for the driver, although the overall system sensitivity may have been lower. I should think the nearest thing would be the SEAS 27TBFCG, even down to the slight roll off at the top end. The Elac was the usual nominal 6 Ohm impedance, IIRC, and had a back chamber like the SEAS, so the fs and corresponding impedance peak should be out of the way of the crossover frequency. It might well just drop in acoustically and electrically- but sadly not physically! If the tweeters are still working and you are looking for an improvement, the Elacs still sound pretty good by modern standards, but there's lots of choice for alternatives apart from the Morels, many of them cheaper and arguably as good or better. You may just get different rather than better though, in the context of the MC-4. On balance I'd probably stick with the Elacs until they break...
 
Thanks very much for that Toaster.
Although I have always respected the transparency and accuracy of the MC4's I would like to improve the listenability and fun factor.
I was hoping that a change of tweeter might achieve this.
Maybe I am on the wrong track.
Especially as I know so little technically which I can appreciate could irritate people on here.
One other thing Toaster. I don't suppose you have any info about the woofer used in the '4's?
 
I was about to say not as an individual unit rather than as part of the speaker- but even as I started to type I remembered that the drive unit was available to DIYers. Of course it's possible that the actual drive unit used by MF was an OEM special, but IIRC it was an 8 inch Audax 'TPX' driver. I may well have the Hi-Fi News review of the complete speaker somewhere, and I might have a datasheet on the driver. Long discontinued now of course. I don't want to put you off improving the speaker of course, but it was a well-balanced good quality design. I've not owned a pair, but I was close to buying a pair in their heyday after a very good dem at a London hi-fi shop. Without wanting to suck all the fun out of the project, I'd suggest defining what it is you are trying to achieve- what are the weaknesses of the MC-4 that you are trying to address? Also, if you're thinking of replacing the mid/bass unit, you are really looking at a new speaker, and if that's the case it may be more sensible to start with a clean sheet of paper.
 
I was about to say not as an individual unit rather than as part of the speaker- but even as I started to type I remembered that the drive unit was available to DIYers. Of course it's possible that the actual drive unit used by MF was an OEM special, but IIRC it was an 8 inch Audax 'TPX' driver. I may well have the Hi-Fi News review of the complete speaker somewhere, and I might have a datasheet on the driver. Long discontinued now of course. I don't want to put you off improving the speaker of course, but it was a well-balanced good quality design. I've not owned a pair, but I was close to buying a pair in their heyday after a very good dem at a London hi-fi shop. Without wanting to suck all the fun out of the project, I'd suggest defining what it is you are trying to achieve- what are the weaknesses of the MC-4 that you are trying to address? Also, if you're thinking of replacing the mid/bass unit, you are really looking at a new speaker, and if that's the case it may be more sensible to start with a clean sheet of paper.

Hi Toaster. I am after the specs of the woofer as I am hoping that then it would be possible for someone to design a crossover to intergrate the new tweeter.
I reckon that the MC4 has a good cabinet and the midrange from the woofer has a very natural sound. The tweeter however has a tendency to be strident and draw attention to itself.
It may be a mistake on my part to think that I am able to distinguish what each element of the 'speaker is contributing.
 
Hi Toaster. I am after the specs of the woofer as I am hoping that then it would be possible for someone to design a crossover to intergrate the new tweeter.
I reckon that the MC4 has a good cabinet and the midrange from the woofer has a very natural sound. The tweeter however has a tendency to be strident and draw attention to itself.
It may be a mistake on my part to think that I am able to distinguish what each element of the 'speaker is contributing.
Maybe new caps... (just an idea, I have the same problem with Mordaunt-Short, Amp/Treble to min.)
 
Yes, you're probably right to attribute that quality to the tweeter, but it can depend quite a bit on the amplifier you are using. Something like an older Mission Cyrus is not the best match, for example. When I heard them with a good front end, with MF 140s (I think) and whatever iteration of the MF pre-amp that matched those, they sounded pretty smooth. The Elac was one of the first 'modern' tweeters and no doubt the latest drivers are a bit better across the board. Apart from the SEAS I've already mentioned, I would suggest the soft dome model in the same series, the 27TDFC, the SB Acoustics SB29 (the small flange neo magnet version might allow you to make up a mounting plate to fit the existing flange rebate) or what used to be the Peerless 810921 'HDS', and is now the Scan-Speak Discovery D2608/9130. I have not heard the D2608, but it is reputed to be very good, smooth but detailed and dynamic seems to be the consensus. I have used the predecessor of the soft-dome SEAS, and that was a good unit- apparently more 'laid back' than the Scan. As I mentioned on another thread recently, I have heard an expensive speaker (a Verity) sounding very good with the SB. No doubt Verity's implementation is good, but it certainly didn't sound like a limiting factor. Given the music being played, delicacy was the main impression, but it should be comparable to the other two technically. If the speakers were mine I might consider the neo SB on the grounds of quality and the possibility of avoiding woodwork, or the D2608, which might be the best match sound-wise. Just speaker builders intuition really though! By all means pm me if you like. I'm about 50 miles North of your location. Meanwhile, if you can hang on 'till the weekend, I'll see if I can turn up some driver info.
 
Thank you very much Toaster and everybody else who has been kind enough to think about this for me.
Thanks to alan-1-b's sugestion, I was able to contact Martin Colloms who was kind enough to reply.
He basically confirmed what I was begining to realise.
That 'speaker design is a very subtle art and just banging an expensive tweeter in was unlikely to lead to sonic Nirvana.
I am very interested in Toaster's informed sugestions but I think that a change of 'speaker may be on the cards.
Thanks again for all the help and advice.:grouphug:
 
before you change anything

Hi Kris,

given some of what you have written since my last Post,
before you change anything, open the cabinets and look at the crossover.

(1) - what Brand Name of capacitors are there, {particually for the Treble Filter's caps}- ?

(2) - if you can follow the circuit on the crossover board, then draw it, and mark all the components locations, and all the capacitors' uF values.
Mark also the + and - Polarity connections for both the tweeter and the woofer to the crossover board.
Post that diagram here.

Post whatever you are able to here, and I will explain next time - I have to go now.
 
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Well, I wouldn't disagree with Martin, particularly as he's the designer, but I wouldn't be too quick to throw the baby out with the bathwater either. If you like most of what the MC-4s do, it may still be better to experiment with a new tweeter than start from scratch. While a new tweeter might not transform a poor speaker into a good one, it could change your perception of the MC-4 to the extent that the positive attributes are retained and improved on, and the negatives reduced below the point where they are an issue for you. Not a very dramatic or exciting way to look at it I know, but there you go...
 
Does anyone have these ?

The tweeter may not have to be changed.

I cannot currently access my copies of the original Review(s) of these l'speakers as they are in storage, (and I don't know in which box of many !).

There was a Review published, with Measurements and Plots,
in either or perhaps both of "Hi-Fi News" and/or "Hi-Fi Choice" years ago, {when Choice used to publish measurements}.

I would like to see the measured Frequency Response plot, and the measured Impedance versus Frequency plot, to study the treble regions of both.

If anyone has copies of the review(s), or knows Links to any now on-line, please will you Post here.
 
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