Mordaunt Short - Carnival Series 2 (1976) Crossover and Tweeter Help Needed!

lhalha

Member
2012-02-05 9:19 am
Hi all,

I am looking for some help and advice on these speakers. They are "working" and I'm confident the main drivers are in good shape but the sound is quite dull, especially from older music / vinyl that doesn't have that crisp electonically-enhanced high end. They also seem to need a lot of power to drive them - possibly to push the tweeters to produce sound and thus overcooking the rest. So I feel the crossovers and tweeters may need some attention - see attached images...

Crossover:

Considering this is a 43-year old circuit, I presume it's worth going ahead and replacing the 2 caps and 1 resistor? There is no visible damage to the caps... But what should I replace with (let's say total budget under $40 AUD)?

Yellow / Violet / GreenCap
4.7 uF ±2% (min:4.61, max:4.79 uF) 500V
Replace with? ECWF2W475JA | Panasonic | Polypropylene Film Capacitors | RS

Black Cap

10uF 50V
Replace with? Soundlabs Group 10uF 50V Mundorf Bipolar Audio Cap

Resistor - Appears to be 6R8 - Replace with ???

Tweeter:

Not sure if this is the original unit. It looks pretty well made, and is mounted on a solid basket. but has no markings other than "8 Ohm" stamped on the outside cone. I can't find any pics online of any examples of this marking (or the crossovers) online!?!?!

The units are pretty dusty / crusty and when I tap them, they give off a bit of a crackly sound, like they are dried out. Should these be replaced or can they potentially be cleaned / restored / moisturised? I am not familiar with tweeter restoration at all!


Thanks in advance,

lhalha
 

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Galu

Member
2018-04-17 6:50 pm
The tweeters look original (see attachment).

The only crossover component in urgent need of replacement is the 10uF ELCAP NP electrolytic - these do not age well! Replace with a good quality electrolytic.
 

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lhalha

Member
2012-02-05 9:19 am

lhalha

Member
2012-02-05 9:19 am
A 100VDC rating would be more than enough. Many would use 50VDC.
The 630V cap would be physically rather large, also.


Oops - thanks mate, was getting my values mixed up. I will stick with this one that I can buy locally: Soundlabs Group 10uF 50V Mundorf Bipolar Audio Cap


The 500V one is the other cap that's there at the moment - I put Yellow / Violet / Green into this site and it gave me:


4.7 uF ±2% (min:4.61, max:4.79 uF) 500V


Maybe the 500V is a red herring, or do those colours specifically denote 500V?



I think what you are saying is, I can replace with anything of the same capacitance value, but > 50VDC and no need to go over 100 VDC.


Should I aim for any specific capacitor type? I'm not sure what type this original multi-coloured part is.
 
Hi all,

I am looking for some help and advice on these speakers. They are "working" and I'm confident the main drivers are in good shape but the sound is quite dull, especially from older music / vinyl that doesn't have that crisp electonically-enhanced high end. They also seem to need a lot of power to drive them - possibly to push the tweeters to produce sound and thus overcooking the rest. So I feel the crossovers and tweeters may need some attention - see attached images...

The (tweeter) units are pretty dusty / crusty and when I tap them, they give off a bit of a crackly sound, like they are dried out. Should these be replaced or can they potentially be cleaned / restored / moisturised? I am not familiar with tweeter restoration at all!


Thanks in advance,

lhalha
lhalha, the tweeters need electrical checking with an ohm meter (DMM), and mechanical checking by gently pushing on the cone (two fingers) and listening/feeling for any scraping which means tweeter replacement is required.
Jaycar have suitable 10uF 100V Electrolytic Crossover Capacitor to replace the original ELCAP electros.
The Polycarbonate cap could be replaced with a modern polypropylene perhaps...Jaycar have these too.

These speakers were never bright or lively but with capacitors type and value selection you may be able to brighten them somewhat.


Dan.


Edit: 50V rating is plenty for these speakers.
 

Galu

Member
2018-04-17 6:50 pm
Thanks Galu! Would this be a suitable replacement?
The capacitors to which you referred in your original post are adequate for the job.

If you find that the tweeters are truly faulty, then look for suitable paper cone replacements - ones with similar physical dimensions.

Such tweeters are not expensive, so taking a chance on buying a pair to see how they blend in would be worth considering - we're not talking ultimate fidelity with these speakers.

Here's a possibility:

VIS TW 6NG: VISATON cone tweeter at reichelt elektronik

The original tweeters are Peerless units - read about them here:

McIntosh Drivers--Tweeters
 

Galu

Member
2018-04-17 6:50 pm
Tweeter: The units are pretty dusty / crusty and when I tap them, they give off a bit of a crackly sound.
According to the link I supplied, the Peerless tweeter has a very lightweight cone/voice coil assembly and doesn't even have a spider to centre the voice coil.

So, after all these years, it is not surprising that the voice coil should be scraping in the magnetic gap, accounting for the 'crackling' sound you have heard!
 

lhalha

Member
2012-02-05 9:19 am
Jaycar have suitable 10uF 100V Electrolytic Crossover Capacitor to replace the original ELCAP electros.
The Polycarbonate cap could be replaced with a modern polypropylene perhaps...Jaycar have these too.


So I am off to Jaycar today, as it looks like they have all these parts in stock. Go Aussie!

For the 4.7 uF - they have both these parts (you can see from the URLs - no need to click) with the polypropylene being $12.50 a pop and the electros much cheaper. In my original image, my understanding from the thread responses is that the multi-coloured cap is not an electrolytic type. So would you advise that I drop the $25 on two of the polys, or could I replace that with a modern electro?

Thanks again for all your help!

4.7uF 250V Metallised Polypropylene Crossover Capacitor | Jaycar Electronics

4.7uF 100V Electrolytic Crossover Capacitor | Jaycar Electronics
 

Galu

Member
2018-04-17 6:50 pm
The muti-coloured cap is a plastic film cap. There is probably no great advantage in replacing it at all!

Technically, you would be best to replace like with like, which means going for the polypropylene cap.

Personally, with this speaker, I don't think either of your three options is likely to be audibly superior to the others.
 

lhalha

Member
2012-02-05 9:19 am
Jaycar have suitable 10uF 100V Electrolytic Crossover Capacitor to replace the original ELCAP electros.
The Polycarbonate cap could be replaced with a modern polypropylene perhaps...Jaycar have these too.


So I am off to Jaycar today, as it looks like they have all these parts in stock. Go Aussie!

For the 4.7 uF - they have both these parts (you can see from the URLs - no need to click) with the polypropylene being $12.50 a pop and the electros much cheaper. In my original image, my understanding from the thread responses is that the multi-coloured cap is not an electrolytic type. So would you advise that I drop the $25 on two of the polys, or could I replace that with a modern electro?

Thanks again for all your help!

4.7uF 250V Metallised Polypropylene Crossover Capacitor | Jaycar Electronics

4.7uF 100V Electrolytic Crossover Capacitor | Jaycar Electronics