My adventures in audio (mostly analogue)

[Shovel_Knight]

I have been a member here for quite a while, but I have never posted anything about my system - until now. I will not provide full photos because my system is not tidy at all, instead I will focus on various components starting with the analogue front end.

This is my main deck at the moment - Technics SP10 mk2 in an Acoustand plinth (custom version for 12-inch tonearms) with SME 3012 as the tonearm. The feet are not really visible in this photo but I use Soundcare SuperSpikes.

http://photo.torba.com/images/pavel.urusov/f1280/2EGv6tZr8YTQ7K2cwZCV.jpeg

Other components to follow...

[Barry]

Very nice Pavel. And well photographed. :)

[Shovel_Knight]

The turntable used to be an ex-BBC SP10 mk2 P/L. When it arrived, it actually worked... sort of. It took some time to lock speed (a healthy SP10 mk2 should lock all three speeds in an instant) and the electronic brake was not functional, meaning that it took a loooooong time to switch from 45 to 33 or from 78 to 45. In addition, the turntable was an ex-BBC model (consistent with its P/L designation) meaning that it required a special interface box to work at all.

The first order of business was to fix the electronic brake circuit, it actually took me several months of occasional poking inside the turntable with a multimeter and a scope, but thanks to Angus (phonomac) I was finally able to trace the fault to a transistor on the logic PCB.

After that, I was lucky enough to buy a "normal" logic PCB on eBay, from Philippines of all places, to replace the special BBC PCB installed in my SP10 mk2. This effectively converted it from SP10 mk2 P/L to the regular domestic model and allowed me to get rid of the BBC control box.

This was what the insides of the turntable looked like after the conversion but before full service:

https://i.imgur.com/BJHZMHhh.jpg#OL5qy

Control PCB recapped:

https://i.imgur.com/zb8ONWJh.jpg#OL5qy

Logic PCB recapped:

https://i.imgur.com/yRSnbQ4h.jpg#OL5qy

Drive PCB recapped:

https://i.imgur.com/hhXu2Eoh.jpg#OL5qy

Adjusting the PLL circuit. Since I don't have a proper workshop, I had to do it in our spare bedroom :-(

https://i.imgur.com/VapHs6Eh.jpg#OL5qy

[Shovel_Knight]

Very nice Pavel. And well photographed. :)

Thanks Barry

[Shovel_Knight]

Servicing the main bearing. Actually, I did it just yesterday. Very simple but requires removing a lot of parts that are in the way.

The heart of the beast:

https://i.imgur.com/CEK9CHlh.jpg#OL5qy

I'm glad I opened it up because the bearing was almost dry and what little oil was there was completely black.

There was a noticeable dimple and a small tear/crack on the old thrust cap. I replaced it with a new one made of Torlon.

https://i.imgur.com/FJgAXW9h.jpg#OL5qy

Thankfully, there was no evidence of wear on the mirror-finished bearing spindle. After cleaning everything with 99% IPA, I applied a couple of drops of synthetic oil to the bearing sleeve and reinstalled the rotor. It took about three hours to fully settle, at which point I was able to reassemble the turntable.

It didn't make any audible difference but I am satisfied that my SP10 mk2 is now good for another 35 years of service.

(Actually, I think I should start a service journal for this turntable: logic board replaced in January 2020... motor unit recapped and recalibrated in March 2020... power supply repaired in April 2020... motor/bearing serviced in December 2020... etc.)

[Shovel_Knight]

Today I set up my Ortofon VMS20E in an original SME headshell and spent the whole day listening to music. The lowly Ortofon is one of my favourite cartridges that does everything right, especially when paired with NOS Ortofon styli. I rate it much higher than any of the 2M cartridges - yes, including the Bronze and the Black! The original N20E mk2 stylus is very high compliance and when paired with SME 3012 the match is marginal at best - even slightly warped records should be avoided. That said, it sounds very nice in a relaxed and liquid way. The (still available) N15XE stylus is a much better match compliance-wise, but doesn't sound as nice as the N20E. I ordered an Analogis "Black Diamond" (nude elliptical) stylus for Ortofon VMS cartridges, hopefully it will be close to N20E in terms of sound quality and not as extreme as the original in terms of compliance.

I also have a Mission 774 tonearm which is waiting to be rewired - this should be a much better match for the ultra-compliant Ortofon.

[Shovel_Knight]

Under the hood of a half-dead Denon turntable. This motor is HUGE! I will save this picture and show it to people who insist that old idlers are special because of their big and powerful motors.

https://i.imgur.com/upngujeh.jpg#OL5qy

Unfortunately, the turntable will require a lot of work. There are many small electrolytes (0.47 and even 0.1uF) which are likely long dead, and all small-signal transistors are of a type which is known to fail in a rather spectacular fashion.

[dave2010]

Servicing the main bearing. Actually, I did it just yesterday. Very simple but requires removing a lot of parts that are in the way.

The heart of the beast:

https://i.imgur.com/CEK9CHlh.jpg#OL5qy


Thankfully, there was no evidence of wear on the mirror-finished bearing spindle. After cleaning everything with 99% IPA, I applied a couple of drops of synthetic oil to the bearing sleeve and reinstalled the rotor. It took about three hours to fully settle, at which point I was able to reassemble the turntable.

It didn't make any audible difference but I am satisfied that my SP10 mk2 is now good for another 35 years of service.

(Actually, I think I should start a service journal for this turntable: logic board replaced in January 2020... motor unit recapped and recalibrated in March 2020... power supply repaired in April 2020... motor/bearing serviced in December 2020... etc.)Fascinating. I've not seen anything quite like that before - but then I lead a sheltered life.

[Shovel_Knight]

Fascinating. I've not seen anything quite like that before - but then I lead a sheltered life.

It is quite similar to the motor inside Technics SL-1200 mk2, only bigger, with more poles, a more precise frequency generator and most importantly - a much better bearing.

[Shovel_Knight]

My SME 3012 lost its headshell socket retaining screw. A brief investigation showed that the plastic inside the socket had become crumbly with age.

The socket was replaced with a new socket made by AudioSilente. It's much better made than the original and a perfect fit for the tonearm.

As a bonus, the locking collar is now much smoother as well, the original one was a bit gritty, especially when used with dual-pin headshells.

[Shovel_Knight]

A nice box of goodies :D

https://i.imgur.com/gRV4E0mh.jpg#OL5qy

Bought this Mission 774 some time ago very cheaply, it was in really poor condition (the wiring was broken, many screws missing, no damping paddles etc.). Got new damping paddles from Xad, gradually replaced the screws (being a British design, this thing uses stupid imperial screws - both BA and UNF, I think?), the tonearm wand has been rewired by Johnnie @ Audio Origami. The only thing still missing is the second antiskating weight.

[Shovel_Knight]

Finally found some time to sort out the Denon.

Replaced components:

https://i.imgur.com/XTXtG8Zh.jpg#OL5qy

And the flying saucer is in the air again!

https://i.imgur.com/6KV5CoRh.jpg#OL5qy

Let's think about it... :scratch:

The armboard is just a piece of MDF.

The tonearm is fixed using only 2 screws and no grommets.

The turntable is sitting on four M6 spikes instead of proper feet because the original feet have perished.

It's running a vintage low-end cartridge connected to a cheap phono stage using a cable extender :eek:

And it sounds absolutely sublime. Seriously.

[Shovel_Knight]

Had a proper armboard made for the Denon, also adjusted the arm's height and the position of the armlift - not a very easy job, the Mission is a very fiddly design. Oh, I also replaced the output wiring with a low capacitance microphone cable (Tasker C128).

https://i.imgur.com/wep6sEuh.jpg#OL5qy

Still using the old Ortofon VMS15XE cartridge and it sounds bloody marvelous. If I was forced to use just one turntable until the end of my life, I would be quite happy with this Denon. At least I can lift it without straining my back, unlike the SP10 / SME / Acoustand combo ;)