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Old 7th Oct 2018, 3:41 pm   #1
kirstyd
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Default Sonotone 9THC cartridge.

Hi all.

The Sonotone cart in my Hacker radiogram needs replacing. Whilst it still works on both channels the rubber ears have hardened causing it to loose Bass and jump on occasion. I don't have another working Sonotone but I do have a few BSR SC12M and H carts that would do but I was wondering if it would be worth fitting a magnetic cart with a pre amp mounted under the turntable. Your thought please people. I have four or five of the Sonotone carts all with the same problem. I have read numerous threads here about people repairing BSR carts with some success. Has anyone tried to open up a Sonotone and do a repair on it?
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Old 7th Oct 2018, 4:46 pm   #2
John10b
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Default Re: sonotone 9THC cartridge

If you take a look at “Bass Response of ceramic cartridge“ Sept 13th, it may interest you, I took some pics of a Sonotone cartridge I opened up.

Cheers , John.
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Old 7th Oct 2018, 5:57 pm   #3
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Default Re: sonotone 9THC cartridge

Might be a forlorn hope if it's gone too far but acetone has a restoring effect on old rubber.
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Old 7th Oct 2018, 6:01 pm   #4
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Default Re: sonotone 9THC cartridge

Is that the headshell from an SP25 or similar? Should be sufficiently good to take an MM cart. I have always been disappointed with phono pre-amps and I found that a little cheapo battery operated one (can't remember make) was about as good as far more costly examples - certainly much better value.
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Old 7th Oct 2018, 9:07 pm   #5
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Default Re: sonotone 9THC cartridge

The deck is a 50 mark 2.
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Old 7th Oct 2018, 9:15 pm   #6
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Default Re: Sonotone 9THC cartridge.

Will try the acetone on one of the old ones first. If it works I will have a go at this one. I have a mains powered pre amp that would fit nicely in the cavity under the deck and could be wired up so that it's only powered up when the turntable motor is in use. I have a brand new Audio Tecknica cartridge in mind for the job.
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Old 7th Oct 2018, 10:32 pm   #7
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Default Re: Sonotone 9THC cartridge.

IIRC, there were different types of suspension used in these. There were the rubber ones and then there were the yellowy nylon type you have. If it is not split, it should be okay - there were several ceramic carts which used a similar setup. Just be sure to use a 9TAHC stylus with a good rubber suspension where it meets the yellow plastic body, and check the tracking weight. I'd be inclined to use no less than 3.5g and no more than 6g.

In my experiences, as with the later 25xx and 35xx Sonotones, ther internal contacts tarnish leading to intermittent sound and weak sound.
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Old 7th Oct 2018, 11:35 pm   #8
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Default Re: Sonotone 9THC cartridge.

Quote:
Originally Posted by kirstyd View Post
will try the acetone on one of the old ones first .If it works i will have a go at this one .I have a mains powered pre amp that would fit nicely in the cavity under the deck and could be wired up so that its only powered up when the turntable motor is in use .I have a brand new Audio Tecknica cartridge in mind for the job
Recommend a little bit of cotton wool soaked in acetone left in contact for a few minutes - if it's really brittle it won't help but it's worth a go - tiny bottles available from your local pharmacist - good for old idler wheels as well. Try a little drop on an unimportant bit of the cart first - to ensure the acetone doesn't react with the plastic (some ketones are used to weld acrylic - but the cart body is very unlikely to be acrylic). The AT cart won't be as sparkly as in a higher compliance tonearm but should sound nice just the same - good luck!
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Old 8th Oct 2018, 8:13 am   #9
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Default Re: Sonotone 9THC cartridge.

I’d vote for a magnetic cartridge. Recently managed to fit a Stanton 500 to a Garrard rc121 mk2, and it works brilliantly, have to Earth the decks metal work properly though and needed to track at 3.4g for the velocity trip to work. I’d have thought this deck could track lighter than that. Styli available online cheap as chips (kyowa- 2 for 15), 78rpm also available..
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Old 8th Oct 2018, 9:54 am   #10
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Default Re: Sonotone 9THC cartridge.

Noting the option to use a MM cartridge, I would recommend you do try to revive your Sonotone. The 9TAHC cartridge is regarded as one of the best ceramics ever made (it measures better than the BSRs you cite) and you are unlikely to hear much sonic difference with the AT91 budget MM you are considering. It's also a great partner for your Garrard deck. Not only will you save money, but possible hum/noise induction.
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Old 8th Oct 2018, 5:57 pm   #11
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Default Re: Sonotone 9THC cartridge.

Yes Edward i would like to keep the sonotone in use if possible so i will try the Acetone treatment and i will give all the metal contacts a good clean failing that its the AT91
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Old 8th Oct 2018, 5:59 pm   #12
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Default Re: Sonotone 9THC cartridge.

Quote:
Originally Posted by ben View Post
IIRC, there were different types of suspension used in these. There were the rubber ones and then there were the yellowy nylon type you have. If it is not split, it should be okay - there were several ceramic carts which used a similar setup. Just be sure to use a 9TAHC stylus with a good rubber suspension where it meets the yellow plastic body, and check the tracking weight. I'd be inclined to use no less than 3.5g and no more than 6g.

In my experiences, as with the later 25xx and 35xx Sonotones, ther internal contacts tarnish leading to intermittent sound and weak sound.
Hi Ben
The suspension hasn't split but its really hard
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Old 8th Oct 2018, 7:51 pm   #13
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Default Re: Sonotone 9THC cartridge.

If you take a look at my post #2 and follow link you will see how tarnished the connections can become.
Cheers
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Old 8th Oct 2018, 10:46 pm   #14
kirstyd
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Default Re: Sonotone 9THC cartridge.

Hi all
i have removed the cartridge and the plug at the back plus the metal case .The four contacts on the plug have been cleaned along with the other four connections inside the back of the cartridge .With the case removed you can clearly see the rubber /plastic rest that the stylus sits in .Its quite hard .I will try the Acetone fix tomorrow wish me luck
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Old 8th Oct 2018, 11:21 pm   #15
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Default Re: Sonotone 9THC cartridge.

I hope it is a rubber mount - not sure acetone will do any good with synthetics!
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Old 9th Oct 2018, 7:27 am   #16
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Default Re: Sonotone 9THC cartridge.

The trouble with acetone and flexible plastic is the softening is usually temporary. A few weeks down the track and the part could be harder than ever. But if the "ears" are rubber and completely hardened, they'll just dissolve into goo. Take care.

Something I've done with a 9TA (the higher output version of the 9THC) is shift the rubber ears and the elements backwards slightly so the ears are closer to the pivot of the stylus. The result is a lower output but better leverage, which compensates for the hardened rubber.
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Old 11th Oct 2018, 1:21 pm   #17
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Default Re: Sonotone 9THC cartridge.

Are you sure it's the 'ears' in this cartridge, as mine is fine still... the STYLI suspensions can harden badly and this happened to my Acos 104 which suffers both issues, but still sounds good, clean and crisp at a now 4g tracking weight, which the 3550/41C, SC11M and 9TA-HC now like - not sure they were ever good at 2g myself, as modern records were cut 'hotter' than back then.
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Old 13th Oct 2018, 10:08 pm   #18
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Default Re: Sonotone 9THC cartridge.

I have just restored one of these, by chance actually, mine was skipping, going quiet then louder, but no where near as loud as it should be, so I striped it down as I was going to nick the rubber suspension for another cart that had its' missing. When attempting to pull the rubber off the ceramics the ceramics came out of the cart, they were filthy so I cleaned them and pushed them back in the slots in the rubber mounts and hey presto booming sound.
The transducers were not soldered to the copper contacts at the back but relied on contact to operate.
Gaz.
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