Monitor audio MA3 crossovers

Kera0004

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Hi just open up my 1976 ma3 to change the caps on the crossovers what a wonderful old smell inside .my question is has any one used Mundorf ECap .seem like good middle ground cap to go with .also dose any 1 know if the orange caps in the picture are film caps thanks for any help Kev
 

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Hi is this what a leaking cap from 1976 looks like thanks for any help
 

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The orange components look like resistors to me and I don't see any sign of capacitors leaking in your photos but if they are leaking then Mundorf non polarised capacitors should be fine.
 
Thanks JBA 2 of them have definitely got yellow paste at the ends 👍👍
 
All the ones with the ++ symbols are non polarized electrolytics normally used to save costs and are smaller than their more expensive Polyester and polypropylene counterparts. The orange component in your pic look like 33 ohm resistors but you won't know for sure until you remove them and look at what's printed on them. They probably won't need replacing tho.
I have used the Mundorf Non polarized caps in a few speaker projects, they're not the best TBH, I found their sound to be poor especially if in series with the tweeter. If you can source them, ALCAP NP's are a lot better for sound quality, I believe Falcon Acoustics still have some stock, give them a call if you can't find the value you are looking for. I think they also do Solen caps.

If you have the space on the circuit board (and budget) to use polypropylene caps on the tweeter circuit then do it but be careful as large values can be physically LARGE and expensive so check sizes. You can find the tweeter capacitor by following the wire from the tweeter to the circuit board, the first caps you bump into are usually them (usually lower values 3.9uf - 10uf) If you are not sure post another picture of the complete circuit board.
The Solen or Ansar Supersound polypropylene caps would be my choice, superb sweet sound and not too expensive.
 
All the ones with the ++ symbols are non polarized electrolytics normally used to save costs and are smaller than their more expensive Polyester and polypropylene counterparts. The orange component in your pic look like 33 ohm resistors but you won't know for sure until you remove them and look at what's printed on them. They probably won't need replacing tho.
I have used the Mundorf Non polarized caps in a few speaker projects, they're not the best TBH, I found their sound to be poor especially if in series with the tweeter. If you can source them, ALCAP NP's are a lot better for sound quality, I believe Falcon Acoustics still have some stock, give them a call if you can't find the value you are looking for. I think they also do Solen caps.

If you have the space on the circuit board (and budget) to use polypropylene caps on the tweeter circuit then do it but be careful as large values can be physically LARGE and expensive so check sizes. You can find the tweeter capacitor by following the wire from the tweeter to the circuit board, the first caps you bump into are usually them (usually lower values 3.9uf - 10uf) If you are not sure post another picture of the complete circuit board.
The Solen or Ansar Supersound polypropylene caps would be my choice, superb sweet sound and not too expensive.
Thanks Kapkirk I've ordered the mcaps so see how the old ma3s sound I'm thinking to do 1 at a time and compare .my next project is a old moog synth not a lot of help out there for this .ones again thanks for you input much appreciated 👍
 
Interested to see how these sound compared to the ELCaps .The readings for these elcap was amazingly close to what they were spect my end up putting them back lol 😆
 

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Yep sound better higher tops no change to mids lot tighter bottom end well pleased
 

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Hi, nice job. Is that one x 80, three x 30, two x 5 and one x 6 pF? I've got two pairs of the MK2 versions. One pair works, one definitely needs crossover rebuild, so I'll do them and see how they compare to the working ones. Did you leave all inductors and resistors in place? Still happy? Any ideas of the MK2 is different? Yours seem to have been quite heavily modified - feet, tweeter, mid surround. Do you think removing the fuse arrangements could be beneficial?

All the best, Tom.
 
I was very tempted to buy a pair of these in 1976, but there again there were some very tempting items on my list.
If I remember the drive units were Isophon, KEF and EMI (elliptical Bass drivers.)
(I already had a Linn Sondek and Naim NAC12S, NAP160, Wonderful then! So much better than anything else at the time.)
 
I was born in 1976 and that's when my dad bought his pair, also with an LP12 (Linn Sondek) but with Quad 33 and 405. Good times! I'm cheating somewhat but the speakers are a lot of fun teamed with my Yamaha RX-V3800 and (obviously) streamed audio. The blend of over sharp modern digitality with the over relaxed nature of the 70's gives me just the right balance (for the second hand buck).

But on the subject of the crossovers, I have just examined my working set, and looked at the picture above, as well as some other pics I found on the web... And they are all different 😱. I mean not just the capacitors have been replaced, but the boards actually have completely different layouts with different inductors too. A bit like we used to say about Italien cars in the 80's, they just used what they had lying about - worked well enough for a while but made repairs challenging!
 
I miss the 70s SO MUCH! And with good reason.

Strange, I first read George Orwells 1984 then, and now we're all living it!

Never thought this before but I'm glad I'm old, but I weep for my children and my childrens children.

Still here we are! The early 80s were fun too for Hi-Fi at least, I've owned the silliest priced exotica and some truly great budget "giant killers" that did so well.

I wish I'd kept more of it, I wish I'd kept all of it! But lots of job moves and house moves both sides of the pond, made that impossible, with hindsight I would have made it possible.
I was born in 1976 and that's when my dad bought his pair, also with an LP12 (Linn Sondek) but with Quad 33 and 405. Good times! I'm cheating somewhat but the speakers are a lot of fun teamed with my Yamaha RX-V3800 and (obviously) streamed audio. The blend of over sharp modern digitality with the over relaxed nature of the 70's gives me just the right balance (for the second hand buck).

But on the subject of the crossovers, I have just examined my working set, and looked at the picture above, as well as some other pics I found on the web... And they are all different 😱. I mean not just the capacitors have been replaced, but the boards actually have completely different layouts with different inductors too. A bit like we used to say about Italien cars in the 80's, they just used what they had lying about - worked well enough for a while but made repairs challenging!
Yeah, relaxed nature of the 70s. I totally understand that, however what you call relaxed I call boring, although the nostalgia is a big pull.
There were speakers back then that were fast and dynamic, anything using KEF Bextrene cones with the heavy HEAVY! Thick layer of dope never stood a chance! (Snoozefest time!)

Regarding the different crossovers you have seen, well designers make mistakes (Martin Colloms designed the MA3, actually all the MA range of that era) Drive unit specs are at times changed by the manufacturer for similar reasons. To be fair the theory of how best to do stuff, changes all the time, in 1976 this was in a great state of flux, which is partly why it was fun.
Also most designers revisit their designs, Audio Research have always made updates, and made the updates available to existing owners.
Component technology has advanced so much since 76, an engineer at NASA JPL labs (CAL) tipped me off about the first Teflon capacitors, WOW!
I could babble on for hours! I usually do, especially after a few beers!
 
Zen57 sound alike you've had more than your fair share of hifi fun! I've had some bits and bobs, mostly old English, but now I would just like something that works! This amp is pretty nice I feel (although maybe not as pure as the Inca Tech IT50 it is replacing) but it can switch the video signal to the in-wall video projector and the Inca Tech can't 🤣. I understand designs evolve, but I am just so surprised to see the seemingly randomness of components... they had a mkI and mkII but even within the mkII it seems pretty mixed up. Anyway I would like to return these things to life but I guess Kera0004 has moved on to other things. Shame, I've got this mess in front of me and would really appreciate some definitive values. Unfortunately this pair have been attacked and not finished, and my other pair have been renewed by
IMG_20221127_115812.jpg
the same fella, and I'm not convinced he was true to the originals. So I have no complete reference.
 
Only Monitor Audio, Martin Colloms and Mo Iqbal will have definitive values, I'd pester all of them until one of them caves.
Oh yeah, I've been having Hi-Fi fun since 1974, (I started when I was still at school.) It was fun back in the day, not so much now. I once collected expensive MC cartridges, I now collect interesting MM cartridges.
At some point in the 90s I owned around 25 turntables, but I wasn't collecting them, but then I had more real estate, cash, and joie de vivre.
I've always had a tonearm fetish, I've probably owned more tonearms than anyone on the planet, some (I mean serious high end designs) you've never heard of.
You have to remember that at the heart of all this is a love of music, without which my fascination for Hi-Fi would indeed be a bizarre fetish.
 
I don't know if this hobby works for the love of music. It seems to me the more I progress my systems, the more picky they get, and more atrocious some of my less refined music choices sound! I seem to remember Linn buying some recording studio or label or whatever back in the '90s so they could properly engineer their recordings to sound perfect on their turntables. Fair enough, but even at the time I thought there was something backwards about the whole arrangement... We shouldn't be choosing the music we listen to according to it's mastering quality!!

I like all sorts and sometimes I think I'd be better of with a midi system, at least that would give everyone an equal chance of sounding crap!

Thanks for the list of likely suspects, I'll try and send a mail or two, but I would feel awkward actually persevering in this instance.

If I do find anything definitive I'll be back to share.

Regards Tom.
 
Well there you have it! For some people Hi-Fi is a "hobby" for me Hi-Fi is simply a tool that enables me to enjoy the music I love in my home.
I've never lost sight of that, back in the 70s when Sheffield Labs introduced direct cut discs they were a huge step forward, but meaningless for me. I'm not a fan of jazz, most of the discs were jazz or classical.
I understand why some are so entranced by the equipment that it is the focus of their interest, it's not wrong thinking or anything, if that's what you want then good on ya!

I also enjoy movies a great deal, with that in mind I choose both audio and video equipment that maximises my enjoyment.
I know that if it was the equipment itself that was the main focus my choices would be different.
Even back in the 70s I had an integrated audiovisual system, not easy back then!
 
I was very tempted to buy a pair of these in 1976, but there again there were some very tempting items on my list.
If I remember the drive units were Isophon, KEF and EMI (elliptical Bass drivers.)
(I already had a Linn Sondek and Naim NAC12S, NAP160, Wonderful then! So much better than anything else at the time.)
Actually BMW, not KEF, I believe.
 
BMW? I didn't realise they were in the drive unit business.
You might have meant B&W (Bowers and Wilkins).
Could also have been Audax midrange, I honestly cannot recall now.
 
Actually BMW, not KEF, I believe.
Not sure about this model, but I think MA in the 80's 90's were using custom versions of SEAS drivers made to their own specs, later they manufactured their own drivers using mainly metal composites.
 
Not sure about this model, but I think MA in the 80's 90's were using custom versions of SEAS drivers made to their own specs, later they manufactured their own drivers using mainly metal composites.
The MA3 dates from the 70s, the MA4 for instance used a KEF B200 (B1039) and Isophon HF drive units.

The MA3 certainly used EMI elliptical bass drive units, Isophon hard dome HF unit, the midrange (I assumed) was a 110mm KEF B110. However I found this image which looks like an Audax unit from the 70s, it was also 160mm and doped bextrene.

Whilst guessing games can be fun, and stretching this memory to the tune of 48 years much less so. Hard facts are what counts. Martin Colloms would know as he designed them.

Both the 160mm midrange and 25mm Isophon drive units were custom designs for Monitor Audio.

PS Doh! Just realised the OP had attached the same images, well I'm old and have no time to read entire threads.

PPS If that's not an Audax midrange I'll eat your hat.
 

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The MA3 dates from the 70s, the MA4 for instance used a KEF B200 (B1039) and Isophon HF drive units.

The MA3 certainly used EMI elliptical bass drive units, Isophon hard dome HF unit, the midrange (I assumed) was a 110mm KEF B110. However I found this image which looks like an Audax unit from the 70s, it was also 160mm and doped bextrene.

Whilst guessing games can be fun, and stretching this memory to the tune of 48 years much less so. Hard facts are what counts. Martin Colloms would know as he designed them.

Both the 160mm midrange and 25mm Isophon drive units were custom designs for Monitor Audio.

PS Doh! Just realised the OP had attached the same images, well I'm old and have no time to read entire threads.

PPS If that's not an Audax midrange I'll eat your hat.
Yeah looks right, I actually prefer the sound of the older Monitor Audio stuff, when they used tried and tested quality drivers.
I also liked the sound of the Audax units, their tweeters especially, prices got very high though, so now a lot of companies manufacture their own like MA.
 
Yeah looks right, I actually prefer the sound of the older Monitor Audio stuff, when they used tried and tested quality drivers.
I also liked the sound of the Audax units, their tweeters especially, prices got very high though, so now a lot of companies manufacture their own like MA.
If you heard them side by side you would be shocked at how bad the older drivers are!
Nostalgia isn't what it used to be!
 
If you heard them side by side you would be shocked at how bad the older drivers are!
Nostalgia isn't what it used to be!
I would have to disagree on that, I gave my old MA R652's to my son 4 years ago, I often go to his place when he has music playing, and they STILL sound very impressive, the bass/mids especially.

I believe the drive units in the 652 & 952 are of very high quality and were chosen by the famous Robin Marshall (later of Epos) for their natural ability to handle high power and roll off naturally with very low distortion, meaning they could be used with simple first order X-Overs (not something many NEW drivers can achieve easily) These were specced by MA and were built by ELAC in Germany, Elac have been around since 1926 and have been manufacturing high quality drive units for many other speaker companies including for their own speakers today) I believe MA also used custom version of SEAS drivers in the past which are also used by PROAC and the like.
 
I would have to disagree on that, I gave my old MA R652's to my son 4 years ago, I often go to his place when he has music playing, and they STILL sound very impressive, the bass/mids especially.

I believe the drive units in the 652 & 952 are of very high quality and were chosen by the famous Robin Marshall (later of Epos) for their natural ability to handle high power and roll off naturally with very low distortion, meaning they could be used with simple first order X-Overs (not something many NEW drivers can achieve easily) These were specced by MA and were built by ELAC in Germany, Elac have been around since 1926 and have been manufacturing high quality drive units for many other speaker companies including for their own speakers today) I believe MA also used custom version of SEAS drivers in the past which are also used by PROAC and the like.
Well ok, depends which R652 we are talking about, they changed around 1986-87.
First I believe they changed the bass/mid driver because the dustcaps (which protect the voicecoil maget gap) kept falling off. Nope they don't make 'em like they used to.
Then later, or maybe at the same time they changed to the metal dome HF driver.
BTW the cabinet was the biggest problem, stiffening braces for the side panels (even very simple) is well worth the effort.

I'm familiar with Robin Marshall, I used Epos ES14 in the 80s in my second system. The bass was rather 'fruity', but there again the amplifiers he was using as a reference at this time were, well I thought a strange choice as it could not resolve the bass that well. It was a nice sounding amplifier though, in its time (1975).

Incidentally the ES14 bass/mid driver did not require any crossover, it rolled off naturally.
In comparison the slightly later, but more expensive ProAc Response 2 did require a crossover network. The results were far superior though. As an engineer who admires elegant, I mean simpler, or dare I say zen like solutions, I totally get the idea that one might expect better results but it doesn't always work that way.

As to new MA speakers you should check ot these reviews of the Silver 500 7G, they're really good!


 
Well ok, depends which R652 we are talking about, they changed around 1986-87.
First I believe they changed the bass/mid driver because the dustcaps (which protect the voicecoil maget gap) kept falling off. Nope they don't make 'em like they used to.
Then later, or maybe at the same time they changed to the metal dome HF driver.
BTW the cabinet was the biggest problem, stiffening braces for the side panels (even very simple) is well worth the effort.

I'm familiar with Robin Marshall, I used Epos ES14 in the 80s in my second system. The bass was rather 'fruity', but there again the amplifiers he was using as a reference at this time were, well I thought a strange choice as it could not resolve the bass that well. It was a nice sounding amplifier though, in its time (1975).

Incidentally the ES14 bass/mid driver did not require any crossover, it rolled off naturally.
In comparison the slightly later, but more expensive ProAc Response 2 did require a crossover network. The results were far superior though. As an engineer who admires elegant, I mean simpler, or dare I say zen like solutions, I totally get the idea that one might expect better results but it doesn't always work that way.

As to new MA speakers you should check ot these reviews of the Silver 500 7G, they're really good!


Hi, Its great some someone remembers the old stuff, Yeah, you are correct about the dust caps on the R652, I must have had the earlier model with the dust caps, and yes I had to re-glue them back on once, along with a few other mods.
I had to add some internal bracing to mine as I was getting some cabinet resonance around 370Hz, and one of the original metal tweeters blew (thanks to a mad session I had once with the solo in comfortably numb) So the tweeters were both replaced with SEAS 27tdfc's, but I didn't like the result, so were again replaced with VIFA XT19's and the crossover completely re designed with a 3rd order Butterworth type (and a hell of a lot of fine tuning and listening) different internal wadding was used and to finish off the cabinets were painted and lacquered. They sounded mighty fine afterwards and still do.

Not been a big fan of the later MA designs but I do hear the 7G's are very good. I did try out the Silver 200's a few years back but they weren't for me.

Below: My Revamped 1980's MA R652's


DSC01257.JPG
 

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