MMC20 Genetic manipulations…

[matador]

Hi guys,

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WARNING: THIS TOPIC MAY BE SHOCKING FOR SOME MEMBERS
Please accept apologies if this is the case.

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Well that being said,

I had that MMC20EN with missing cantilever that came loose inside a Beogram 4002 in addition to the one fitted to the deck. I thought to have it restored but when you’re on a budget, cartridge repair is not an easy journey: prices, terms, possibilities of repair or not and did I already said “prices”?

Anyway, one day after further inspection, I discovered the cantilever was not missing, it was broken.

And it was hollow! So first thing was to find something to fill that hole. I tried:

• Cactus needle -> too thick.
• Sewing needle -> too thick.
• Copper wire -> too soft.

I finally use a metal strand from a wire brush, it was perfect in diameter (0,25mm).

Next I needed to have a stone on the other end. All this being very uncertain I didn’t want to spend a lot so I bought chinese bulk saphirs: 3 for 6€.

They arrive like one week after:

Next step was to cut the cantilever at the right length with an cutter and insert the strand in it with a drop of glue:

Cut the strand and insert it the remains of the old cantilever:

Right now it is not glued and the original cartridge has remain unchanged. but the friction is enough to be able to try it like that. And…

… Believe it or not, it works! I can ear bass, treble, high, no rumble or something, no distortion at least at average listening levels. Output level is similar to my MMC20S.
I tried it on a quite old and used record but, to me, the concept is working.

Now I need to decide if I go along and glue the needle after refining the azimut or if I stop the experiment here to maybe have it restored one day. I’ve got two MMC20E, one in use and the other one NOS as backup. I also understand, by now the suspensions must all be dead or at least worn. But a spare cartridge just to check a deck is working is always useful. And not being a so serious listener it may even work for background music, In all case better than a non working one. Also it makes me think that with the right tools and dexterity, a lot of things can be made.

Cheers!

 

 

[YannChris]

Thumbs up!

[geoffmartin]

Too bad you’re in France and not next door. I’d be interested to measure this to see how good/bad it turned out!

On the other hand, I have some broken cartridges lying around. I might just try to duplicate your results by making some franken-pickups of my own…  🙂

I’m curious about the “chinese bulk saphirs”…

Cheers

-geoff

[matador]

Oh, God!

I was expecting all sort of reactions but absolutly not your curiosity Mr Martin!

To answer two quarters of it:

• Not need to measure: Sapphires are at best spherical so, in my understanding, less good than any other shape. They’re also softer so prone to wear quickly and therefore, damage the record (still after my google wisdom understanding). I don’t even talk about parameters I don’t master like stifness of the cantilever or anything like that (you may not be aware of, but there is a 20 pages “technical sound guide” about beograms, I’m not sure I’ve shotcuted with a 10€ trick!).
• The Chinese bulk sapphires are replacement parts for low cost record players that all use the same cheap needle. You find them on the bay, here in France “à la FNAC” and maybe in every similar tech store around the world. A little reading will teach anyone they share nothing with the lowest even not B&O tip.

And to answer the last bit:

• I’m still happy because despite all the above it did still work “not outrageously bad”.
  It shows this is possible and be done better with better skills or care or money. For instance by replacing the cheap sapphire with a diamond or using a better strand or whatever else. Maybe just with more steady hands and a better magnification device.

One midway solution would be to be able to use that sapphire or any other tip if it could be glued strong but unglued easily.

In any case, I know this will be like a slap in the face of any well serviced Beogram, but experiments need to start somewhere!

Regards.

M.

[chartz]

Hi,

Good idea.

Done that, been there! The telescopic repair, I mean.

The MMC is worth a better stylus of course.

I have just repaired a DL103 with broken cantilever (keeping the original broken cantilever). I used a tiny medical needle, and believe it or not, the cartridge sings perfectly.

The SP series are easy to do because they have a spigot on which you can attach the alu tube, with moderate force. No need for glue.

I think the MMC4000 has the spigot too.

[matador]

chartz wrote:

The SP series are easy to do because they have a spigot on which you can attach the alu tube, with moderate force. No need for glue.

Hi Chartz, is this in all SP? I’ve looked at SP10 and SP12 and cant see anything?

[geoffmartin]

Hi again,

No need to make excuses… I’m genuinely curious! I’m currently in the process of turning two sick 42VFs into one healthy one – but I don’t have many pickups with the cantilever still attached (the end result will have the 20º tonearm – not the later 15º version, and the SP1-2 pickups are hard to find in good condition…) Given the way I’ll be using this turntable (mostly with my 78 RPM disks) a DIY pickup rebuild would not be crazy.

I’ll have a look around for the sapphires – maybe I’ll have to call in a favour from an audio geek friend in Paris to look around the next time he’s at FNAC if I can’t find my own around here in the fields of Jutland… 😀

Thanks for the inspiration! Nice work, in my opinion!

Cheers

-geoff

 

[geoffmartin]

I forgot to add…

> you may not be aware of, but there is a 20 pages “technical sound guide” about beograms

I am aware of it… I wrote it. 🙂

 

EDIT: I didn’t realise it was a joke. I’m a bit thick this weekend, apparently. Sorry… 🙂

Cheers
-geoff

[matador]

geoffmartin wrote:

Given the way I’ll be using this turntable (mostly with my 78 RPM disks) a DIY pickup rebuild would not be crazy.

Hi Geoff and thank you for your kind words.

I’m not sure of that but I think 78 RPM records are made of a softer material than modern records. Not a problem when the needle is new, but I’ve read scary things when the tip starts to wear. And sapphires wear quickly (less than 100 hours against 1000 for a diamond, I’ve read), even more when the tracking force is high like it was in old turntables.

I can’t find and old advert that says something like “worn stylus are chisel for your records” but in all case you should maybe check before dropping any needle on your disks.

Regards.

 

[chartz]

Hi,

Here’s an MMC4000 and an SP12 to illustrate what I wrote above. It’s fairly easy to fit a new cantilever provided the diameter is compatible. ☺️

Jacques

[matador]

Thank you Chartz,

If I understand well, in SP’s the cantilever is “plugged” on the prong that protude from the cross, right? Then you would just need to “plug-in” a new hollow cantilever over it isn’t it?

Then how do you take out the cross and rubber part out of the SP shell? Is it glued or do you just need to push?

And to remove the previous cantilever you just need to pull it?

[chartz]

It is glued. You need persuasion (and some patience) to remove the thing.

To remove the old one you need to cut it longitudinally, if that makes sense.

[matador]

chartz wrote:

To remove the old one you need to cut it longitudinally, if that makes sense.

Like the belly of a fish? But on a that thin tube how would you do that?

[chartz]

With the tip of a cutter blade.

[matador]

Thank you. Not sure my hands are steady enough but I’ll try when needed!

[geoffmartin]

It’s a good question – but I think that shellac (+ limestone) 78s are harder than PVC 33s. Also, the groove is MUCH wider, so there’s plenty of room for error.

Either way, it’s worth a try. Thanks for the ebay link you sent. This will give me a new project once the days start getting shorter here in Denmark.

Cheers
-geoff

[matador]

geoffmartin wrote:

but I think that shellac (+ limestone) 78s are harder than PVC 33s.

I thought it was the other way around but after further reading, you’re right!
Thank you for correcting me.

Please let us now when you’re there and tell us how it worked.

[matador]

Stereomensch wrote:

Anyway, I think B&O uses in Europe Axel Schürholtz needles as a replacement.

To be honest I don’t know Axel Schürholtz and I don’t want to be disrespectful to anybody, but my experience with retippers has always been unpleasant. Not in the work that as been done, but in the interaction with the guy.

This lead me to try this, and the reactions to this topic from Charte or Geoff encourage me to work harder to refine the solution until the result is enough for my needs (by fitting a better tip for example).

[Stereomensch]

Anyway, I think B&O uses in Europe Axel Schürholtz needles as a replacement.

 

https://www.tonabnehmerservice.de/B-O-MMC-Systeme/

[chartz]

Yes it is glued, but it can be opened with some care. Not for the faint of heart though.

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