Customized Magnavox Micromatic

For the past few years, I've been using an EL84 Single Ended Pentode tube amp I built out of a Magnavox amp. It came from a suitcase style record player that belonged to my grandmother.

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Last year I decided to do the same with the Magnavox (Collaro) Micromatic changer from the same suitcase player. I'd like to share my progress with this forum, from which I have learned a great deal about hifi designs.

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All automatic functions were stripped out. What remains is merely an on/off switch and a speed change knob.

I'm using the AT-XP5 cartridge, which tracks at the same force as the original ceramic. The original acrylic tonearm was heavily modified to accept the 1/2" cartridge. It is easy to change cartridges.

The plinth is solid 3/4" thick Patagonian Rosewood, 5 1/2" tall. Black acrylic laminated over plywood makes the top. I bought a new idler from Gary at Voice Of Music, V-M Audio Enthusiasts and it is very smooth-rolling and quiet. New center bearing.

Original rubber mat is supple and does a lot to attenuate rumble. Even on 45rpm, the rumble is totally acceptable to me. Disappears once the music starts.

If anyone is interested, I've been writing up in detail a lot of the work I did, and I'll continue to do so here: Hifi – FOR MADMEN ONLY!. Lots of higher quality photos, too.

Thanks for all the great posts that helped me along the way! Maybe this will inspire someone else.
 
I love the machine work, polishing, finish, attention to detail.
While I respect domestic manufactured goods, I had some LP's the highs were plowed off in one play by a ceramic cartridge from RCA. Mother's Top Value stamp prize stereo. Irreplaceable Mercury Living sound LP's in some cases. Changing the needle didn't help. No more 5 g tone arms for me.
I found the college library using AR turntables which left the public LP's with intact highs. When I was making $1.85 an hour I saved up for a used AR turntable, and never looked back. I'm now using a BIC 940 changer with 1.5 g tracking, a M97 Era IV cartridge, and have hundreds of LP's that are undamaged.
Some years ago I could have bought a CD reissue of C R Fine engineer recordings for only $300. When I didn't have social security yet. Sigh.
 
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Just a quick update: after listening to the turntable off and on - then checking with a strobe disc - I determined that the speed was slightly slow. I solved that by cobbling together a new motor spindle/pulley for a few dollars worth of brass stock. The "Micromanual" is now a two-speed table (33-1/3 and 45) but the speed is quite accurate.

I outlined my work here: Magnavox Micromatic: Speed – FOR MADMEN ONLY!
 
About two years ago, I sold off a nice Imperial Micromatic 600 to a customer.
Naturally, I completely overhauled the machine, which came on an oak veneered wood base.
I chose a Pickering cartridge tracking at 3 grams for it, re-wired the tonearm with ultra flexible shielded wiring.
The mechanism was in perfect condition, lubed, adjusted, etc, and with new drives and rubber was utterly silent, speeds dead on with the synchronous motor. (the Imperial versions used synchronous motors).


The customer loved it, and even sent me pics of it in his house.
I'm sure it'll give him good performance for decades - the Collaro's are well built British changers.


My CL ad pic...
 

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About two years ago, I sold off a nice Imperial Micromatic 600 to a customer....

Beautiful! Yes, my impression is that they are built like tanks, with the same quality seen in Garrard and other venerated changers.

How does one know if the motor is synchronous? Are you sure all Imperials had synchronous motors? I'd love to obtain one and see how it performs.

I can't say my "Micromanual" is that quiet. Even with my newly rebuilt idler, which works very well, there is definitely rumble to contend with. Only through the platter; the tonearm picks up not the slightest noise from the deck.
 
Beautiful! Yes, my impression is that they are built like tanks, with the same quality seen in Garrard and other venerated changers.

How does one know if the motor is synchronous? Are you sure all Imperials had synchronous motors? I'd love to obtain one and see how it performs.

I can't say my "Micromanual" is that quiet. Even with my newly rebuilt idler, which works very well, there is definitely rumble to contend with. Only through the platter; the tonearm picks up not the slightest noise from the deck.


With a synchronous motor, if you spin the shaft/fan with your fingers, and it comes to a stop, rocking back and forth.
Non-synchronous motors just spin to a stop, no rocking motion.
I was a Magnavox registered technician, so I know these products well.


The platter bearing assembly can be improved on by replacing the bottom dimpled washer with a 2mm silicone rubber one, and filling the ball bearing race with Super Lube - also a smear of Super Lube on the spindle itself.
Motor mount bushings go stiff from age, and new ones make a difference.
The polished washers against the platter's ball race must be perfect and not scratched or blemished.


There's a whole lot of things that I do to get the best from these machines.
 
With a synchronous motor, if you spin the shaft/fan with your fingers, and it comes to a stop, rocking back and forth.
Non-synchronous motors just spin to a stop, no rocking motion.
I was a Magnavox registered technician, so I know these products well.


The platter bearing assembly can be improved on by replacing the bottom dimpled washer with a 2mm silicone rubber one, and filling the ball bearing race with Super Lube - also a smear of Super Lube on the spindle itself.
Motor mount bushings go stiff from age, and new ones make a difference.
The polished washers against the platter's ball race must be perfect and not scratched or blemished.


There's a whole lot of things that I do to get the best from these machines.

I thought the dimpled washer was vital to reducing wow. Wouldn’t replacing it with a rubber washer affect that?

I’ve replaced the top rubber washer with a new, soft one cut to size. The motor mounts are still very soft, but I have new replacements on hand just in case.

Is super lube thick? I used an automotive lithium grease for the center bearing.

Are the synchronous motors the ones with no fan? I recently worked on a “Magnavox Custom” from around 1966 I think, and the motor was a bit different, with no fan.

Thanks for the tips! There’s not a lot of information about these units on the internet, and they certainly don’t get the attention that other idlers do.
 
I thought the dimpled washer was vital to reducing wow. Wouldn’t replacing it with a rubber washer affect that?

I’ve replaced the top rubber washer with a new, soft one cut to size. The motor mounts are still very soft, but I have new replacements on hand just in case.

Is super lube thick? I used an automotive lithium grease for the center bearing.

Are the synchronous motors the ones with no fan? I recently worked on a “Magnavox Custom” from around 1966 I think, and the motor was a bit different, with no fan.

Thanks for the tips! There’s not a lot of information about these units on the internet, and they certainly don’t get the attention that other idlers do.

The dimpled washer is only designed to take up any wobble of the ball race, and removing it doesn't make any difference in wow/flutter.
What does make a difference is replacing it with a silicone washer of the same diameter and thickness (1.5-2mm) because it further isolates the platter from the main chassis, thus reducing transmission of any motor-related hums.

As for the motors, it's possible that someone before may have removed the fan blades - I've seen that a few times.
Actually, those motors really don't need a fan anyway.
They don't run that hot to need one.

As for lithium grease - NO... it's old school crap and dries up over time.
Super Lube is a synthetic, clear, very light gel, with slippery teflon, and I use it on many moving/sliding/rotating parts - and stuff I repaired 25 years later, is still clear, slippery, and clean, unlike old greases that get dirty.

As for "the internet" - don't believe a lot of things that you read - I'm an old tech with much more common sense and experience (45+ years) than most internet bloggers.
 
Super Lube is a synthetic, clear, very light gel, with slippery teflon, and I use it on many moving/sliding/rotating parts - and stuff I repaired 25 years later, is still clear, slippery, and clean, unlike old greases that get dirty.
Mouser, digikey, arrow, parts-express, don't have super lube. Farnell has super lube from loctite in the UK. !@# My 1979 BIC 940 turntable just started running slow for the first time last week. Until then, no maintenance. Probably 10000 plays or more.
 
Mouser, digikey, arrow, parts-express, don't have super lube. Farnell has super lube from loctite in the UK. !@# My 1979 BIC 940 turntable just started running slow for the first time last week. Until then, no maintenance. Probably 10000 plays or more.


Most hardware stores carry Super Lube.
Ace Hardware, Home Depot, Lowes, Harbor Freight, etc.
 

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