Changing arms on a vintage TT

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Ellis Wyatt
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Changing arms on a vintage TT

Post by Ellis Wyatt » 19 Jul 2018 01:33

I recently purchased a mechanically perfect Glenburn AT 100. The cartridge is shot (sound output favors the left channel over the right, overall sound is tinny to the point of actually hurting my ears even if the receiver is set at what most people would consider a reasonable listening volume, and completely static ridden) and I have discovered that it is hard to find replacements. Also, as much as I love the 854 style stylus, these are becoming increasingly hard to find, too.

Everything I've read about this TT suggests that its sound could be radically improved with a new aftermarket arm and cartridge. Since it needs a new cartridge anyway it makes sense to consider replacing the entire arm. My questions, then, to you kind readers:

1. What mechanical considerations must I account for if I do this, (e.g., length of arm, new arm weight vs. old arm weight, tracking weight/anti-skate and other adjustments, etc.)? Detailed responses to this question are greatly appreciated.

2. Assuming it is possible to find a suitable new replacement arm, which arm and cartridge combination should I consider? My only two criteria here are that the arm/cartridge shouldn't cost more than $300 combined, and the cartridge should be easily available in the future.

3. Would it be possible to use a Realistic Lab-420 arm as a direct replacement? (I know this one is a bit specific, but it can't hurt to ask.)

Thank you for your consideration and replies!

Alec124c41
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Re: Changing arms on a vintage TT

Post by Alec124c41 » 19 Jul 2018 02:18

That is, as far as I can determine, a BSR changer. You can't change the arm without losing the automatic features that make that what it is. Just buy a new stylus or cartridge. It was very popular in a time when piling on a stack of records considered normal.
You could rip out all the automatic features, and put another arm on, and have a manual turntable. The arm should be the same length, pivot to stylus. The Lab-420 is 220mm.
It might be easier to take your $300, and buy an old Technics turntable. Or fix up the Lab-420, if it is available.

Cheers,
Alec

Spinner45
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Re: Changing arms on a vintage TT

Post by Spinner45 » 19 Jul 2018 03:53

Alec124c41 wrote:That is, as far as I can determine, a BSR changer. You can't change the arm without losing the automatic features that make that what it is. Just buy a new stylus or cartridge. It was very popular in a time when piling on a stack of records considered normal.
You could rip out all the automatic features, and put another arm on, and have a manual turntable. The arm should be the same length, pivot to stylus. The Lab-420 is 220mm.
It might be easier to take your $300, and buy an old Technics turntable. Or fix up the Lab-420, if it is available.

Cheers,
Alec
Alec, I agree.
Those bottom-line Glenburns were the cheap knockoff of BSR's, and not really worth repairing.

Ellis Wyatt
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Re: Changing arms on a vintage TT

Post by Ellis Wyatt » 19 Jul 2018 04:02

Thank you both for your replies. I can do without the record changing feature--even when I was a kid that didn't make sense ("Hey, want an easy way to damage records? It's built right into your table!") so I'm okay with turning it into a manual machine.

Spinner mentions an interesting point I keep running into on the internet. From a mechanical perspective, the TT I have works perfectly. Sound reproduction is the only sticking point. While I get that Glenburns were knockoffs of BSRs, and BSRs were knockoffs of another company's product, what I don't get is how one could draw the conclusion that a TT is bad if the main bad point of the unit is corrected. Unless I'm wrong to think that a mechanically perfect TT is a mechanically perfect TT regardless of the brand, wouldn't changing the arm/cartridge and making appropriate adjustments effectively make the TT "good"?

(I approach this from a car perspective. A brand new car with a shot transmission can become a brand new car again if you simply repair or replace the transmission. Shouldn't this be the same rationale with arm replacement, or are minutia like the motor type which powers the dd system relevant to the argument)?

Thanks again!

Ellis Wyatt
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Re: Changing arms on a vintage TT

Post by Ellis Wyatt » 19 Jul 2018 04:11

Alec, one additional technical question. When you say a replacement arm should be the same length from pivot to stylus, do you mean the same length from the center of the pivot to the approximate center of the stylus "point", for lack of a better term? Thanks!

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Re: Changing arms on a vintage TT

Post by Spinner45 » 19 Jul 2018 04:28

Those budget record changers were geared towards people who didn't care about good sound, they just wanted something cheap to play records on. - casual listening.
Rumble, flutter, etc were high, speed accuracy was all over the map, but those people weren't "keen" to those things, and were nevertheless satisfied.

Stacking records is not a bad, dangerous thing, despite what the internet connoisseur's say.
It's just an old wives tale that never seems to stop rearing its tired head.

The Glenburn's used a 2 pole induction motor that is bottom of the barrel, and changers of that era were made when record changer companies were on their way out, so heavy cost-cutting was the name of the game.

Alec124c41
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Re: Changing arms on a vintage TT

Post by Alec124c41 » 19 Jul 2018 04:46

The smoothness of the rotation of the platter, the vibration of the motor, the rumble of the bearings, these will all deteriorate the reproduction of the music. So a turntable is a turntable is a turntable ... falls apart pretty quickly.
Some turntables are less mechanically perfect than others, to start with.
Would you think that a mechanically perfect Lada was in the same league as a Volvo?

Cheers,
Alec

Alec124c41
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Re: Changing arms on a vintage TT

Post by Alec124c41 » 19 Jul 2018 04:48

Ellis Wyatt wrote:Alec, one additional technical question. When you say a replacement arm should be the same length from pivot to stylus, do you mean the same length from the center of the pivot to the approximate center of the stylus "point", for lack of a better term? Thanks!
Correct. Otherwise, the arm would have to be mounted in a different place.

Cheers,
Alec

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Re: Changing arms on a vintage TT

Post by Sunwire » 19 Jul 2018 05:10

If you really have $300 you can spend, you would be FAR better off spending it on a totally different turntable.
You cannot make the AT100 into a "good" turntable. Even if you spend all of the $300 on it.
The bearing and drive system and the chassis all have inherent problems. It's not just the tonearm.
To fix them, you would need to replace or radically change all those parts. You would essentially have a different turntable and it would still look like the cheap record changer it is.
REALLY, it's NOT worth it.

I have bought a half dozen or more FAR BETTER turntables for $35 or less.

Ellis Wyatt
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Re: Changing arms on a vintage TT

Post by Ellis Wyatt » 19 Jul 2018 21:03

Thank you again, everyone, for your replies, and to Alec especially for the mechanical insights. As someone inclined to tinker, I actually see merit in using the TT I have as an ongoing project of sorts, even if it ultimately turns out to be an entirely different machine at the end.

Considering this, a new question: say I get rid of all of the changer components, to turn it into a vanilla, manual TT. Once those components are removed, and presuming I can find a complete arm assembly which fits, is the next step in the process simply to remove the existing arm/wiring harness, drop the new arm in, and solder?

Ellis Wyatt
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Re: Changing arms on a vintage TT

Post by Ellis Wyatt » 19 Jul 2018 21:07

Alec124c41 wrote: Some turntables are less mechanically perfect than others, to start with.
Would you think that a mechanically perfect Lada was in the same league as a Volvo?

Cheers,
Alec
I like this comparison. I suppose variables do matter depending on expected quality. The TT I have isn't meant to function as a Dual would--more as a daily driver with a few quirks, rather than a properly maintained Rolls Royce show car. :D

Alec124c41
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Re: Changing arms on a vintage TT

Post by Alec124c41 » 19 Jul 2018 21:16

Different arms are mounted in different ways, so some tinkering might be necessary before you can "drop in" the new arm.
Whether you end up with another turntable or not, tinkering is a learning experience.
You might later convert this to a record cleaning machine.
The Duals would be considered daily drivers, but not in the Rolls Royce strata. Buicks or Oldsmobiles, perhaps.

Cheers,
Alec

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Re: Changing arms on a vintage TT

Post by Copperhead » 20 Jul 2018 01:59

Ellis Wyatt wrote:. As someone inclined to tinker, I actually see merit in using the TT I have as an ongoing project of sorts, even if it ultimately turns out to be an entirely different machine at the end.
You will have trouble finding any component that will be decent enough for a project, unfortunately.

Your talents would be better applied to something with more potential. A Dual CS505 needing Help can often be bought for peanuts, even a basic Japanese budget turntable would be a good starting point.

My loft is full of turntables I bought hoping to modify, the platters and motors are mostly not worth using. These parts,together with the arm, are the most critical components needed for a half decent project.

In the end you will be chasing inconsistent speed and noise caused by mediocre components till you replace the offending items.

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