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Linn Sondek DIY mods that work
Linn Sondek DIY mods that work
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Old 28th April 2015, 12:27 PM   #151
Hiten is offline Hiten  India
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Thank you sir.
Would isolation/damped coupling of Linn motor be of any advantage ? I see it is coupled directly to the plate. Also would mass loading the armboard be of any help ? OR a armboard of various material.
I know the suspension springs of Linn rest on rubber grommet but another mod, (I don't know how it would help) is putting a rubber sleeve on the spring metal wire.

Maybe I am thinking too much on vibrations and isolation, which people say if overdone robs the liveliness of a turntable. I wonder how a shortest, direct coupled turntable (i.e. platter-bearing-tonearm. so that vibrations/resonance is easily and quickly transferred from stylus to platter to tonearm and vice versa) would sound like.
Regards.
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Old 28th April 2015, 12:44 PM   #152
sq225917 is offline sq225917  United Kingdom
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Don't cover the springs with anything, it will only act as a short circuit. Softer grommet material will help reduce the transmission of vibration at certain frequencies.

I run a Kuzma Stabi, where the arm mount and bearing mount are on the same massive 60mm thick brass cyclinder. The motor pod is remote. It works well is low noise, and is very lively sounding.

Click the image to open in full size.


Nigel by way of example here's the above deck using a standard LP12 motor with a Hercules and a Geddon power supply.

Click the image to open in full size.

Here's the same deck with the same motor but with silicon bearing oil.
Click the image to open in full size.

I can't find the graph for the Project 16v motor and current fancy PSU, but it's better again.
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Old 28th April 2015, 01:05 PM   #153
nigel pearson is offline nigel pearson  United Kingdom
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That's a very good method. I know Frank. A really nice guy and very modest about his work. His air bearing arm is interesting. The air is like a capacitor. As more presure is had the bass improves. More air micro farads.

As for the motor I can only see what I have shown before as a pathway. The 2 x 220 uF 250 V and isolation transformer nice and easy.

The spring is an echo chamber. The rubber stops that rather too well. It can be super tuned. I could imagine polyetherlene rubber as being better ( no idea if that is the real name for it, softer grades ) .
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Old 30th April 2015, 08:31 AM   #154
nigel pearson is offline nigel pearson  United Kingdom
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The drag = improvement was something we had to get right with the Garrard 501. Some of the folklaw put about is simply wrong. Not subtlly wrong at that. One bearing we tried took a day to come to speed and lost it in 10 minutes if switched off. The surface finish is mostly about people looking at bearings, 1 micron is only because it is easy enough to do. One bearing we tried had furrows. It was excellent. It was even made from stainless steel which is totally unsuitable. Stainless can be high speed turned to glaze it. That makes it OK, if working stainless steel go slow until you want it hardened. The 501 has the last process as that on the chassis. RR of Darby helped. We were cheeky enough to phone them asking who was it who wanted 5 to slip it in the Rhodium tank at midnight. They were very helpful and said the Rhodium is only to get a finish and we should be proud of our machining. The advice given was basic machine cut bottom. Inner surface fine finishing cut. Outer edge hand polished. If you look back to the link I gave of the German review you will see that. The bottom is almost rough in contrast to the motor. It is beautiful rough. Garrard also had this. 1 is front, 2 is sides, 3 is under platter and 4 is deck bottom. 1 has to be the most perfect. Garrard and RR worked togther in the war. The 401 platter made on RR machinery ( Vickers Swindon, now Honda ). As far as I know Garrard were the only company ever to be in a joint advent with RR. RR would love a copy, it was a 301 and in USA. Bob and myself were in the engine room of his RX7 with a 301 perched on the whatever a rotary engine has other than the rocker cover and obviously happy. A German man asks ironically " What is this about ". Martina a friend said " This is called joy ". Bob's RX-7 was better than when if left the factory and >400 BHP. The photo was just an accident as it was engine inspection time and the 301 was in my hands. The engine had just grown cooling pipes I think. The engine didn't last long. I had advised this. As much as Bob wouldn't agree I would have fitted a Rover V8. It would have used much less fuel! A Rover will do 350 BHP and be OK. It won't do 410, the crankcase isn't strong enough. The pistons hit the head and on the centrifical side. Cosworth pistons are tough. After a remachine thery went back in.

Garrard and Porsche

The Garrard bearing is not like the LP12 or others. It can work for 50 years with only 55(C) Rockwells of harness, Linn I think is 64 like SME. What people get wrong is the bearing needs the largest possible clearance with a nice finish. This allows a better type of oil to be used. Even so SAE 30 is about the limit. Verdier used Rockol Lathe slide base oil ( red ). Motorcar oils seem unsuitable due to aditives. The synthetics more so. Garrard used hydrolic fluid as used in JCB's. I dare say ATF would be similar. The original Linn oil might have been for sewing machines as the Linn factory had made the industrial Singer machines. Jack Tiefenbrum on coming to Scotland found the sewing mahiines not able to do industrial work. He set about modifying them. Singer liked it and this in the end became Catlemilk Engineering.

Original Rega bearings used EP 90. A man said his deck was doing 31 RPM ( for me it was fine ). On phoning Rega they said it must be at about 10 C in the house. It was 5 C! It was an old tower block in Birmingham I think? Although the room was a bit warmer the place where the turntable sat was 5 C. On this evidence the guy got relocated. Some Rega's pully's come loose. Careful with the Superglue to avoid the phosphor broze bearing.


If a friend has a Lenco 75 I would love to see it do your circle test. What is the test set up ( test disc I assume )? I suspect if a Lenco's arm has OK knife blocks it would suilt Denon DL103/110, Goldring 1042. It's not very pretty as about the worst I can say about it. Mr old boss has a Lenco GL99 for me. That will be interesting. It isn't the best looking and much like a biscuit tin when the chassis ( Linn thickness I guess ).
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Old 30th April 2015, 11:07 AM   #155
sq225917 is offline sq225917  United Kingdom
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Nigel, send me his address and I'll post him my pressing of the test record to use. All the other tests used my copy of the record to ensure comparable results due to eccentricity etc. he just needs to record the first 30 seconds in 16bit/ 44.1 and email me the WAV file and I'll forward it on to PaulR.

I had the Goldring G99 a few years back, nice motor and bearing, bloody awful chassis though.
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Old 30th April 2015, 01:16 PM   #156
nigel pearson is offline nigel pearson  United Kingdom
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Thanks. If I get the GL99 working I should do that.

Biscuit tin is about right. What bothers me about GL75 is it took 50 years for people to say how good it is. A lady asked me to install a hi fi for about 1000 in a very posh apartment in Park Town Oxford. I jumped at the chance to see inside the building. Sort of thing the series Lewis will uses as a back drop. She did it on the understanding I fixed up the Lenco. She was embarrased to ask. That's the day I woke up to how good they are. She had known the real Von Trapp familly. The Sound of Music had ruined their lives it seems. She had worked in steam ships all her adult life and collected records. This was the first time they had been played.

At Loricraft Audio a GL75 was dropped off for the boss of a valve company. We used GL75 at the time as part of record cleaning machines as did Audio and Design Ltd in 1968. Unfortunately no one told Guy our chap who did this. As Terry said the Lenco 75 went to Guys slaughter house and was no more. I pieced together the plinth and gradually built up a replacement, the original plinth somehow was OK. This was fitted with a Goldring 1042. It was very very good.
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Old 6th December 2017, 03:49 PM   #157
diybry is offline diybry
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I have followed this (old) thread with interest, especially the possibility of designing an improved sub chassis for the LP12. Has anybody successfully implemented such a thing?
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