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401 newbie

F

Frankiesays

Rats is life.
Just got a 401, in a lead lined SME plinth, was serviced a few years back, runs nice and quiet. Stuck a 750 arm on it, with a Nagaoka mp 200. Bass is a bit bloomy, overall sound somewhat raw. Though arm cannot be raised quite high enough as yet, waiting for the correct tonearm cable. What's my next move? Any basic info for things to check? Ta.
 
I'd priortise getting a better plinth. If it's quiet and runs at the correct speed I think you are good to go otherwise!
 
Try to get the arm a bit higher for a start, and down the line try a different plinth, I’ve had the SME style, a slate box and currently a stacked ply with graduated cut outs through the layers and I prefer it to the others. Easy enough to DIY too.
 
Rob998 said:
Try to get the arm a bit higher for a start, and down the line try a different plinth, I’ve had the SME style, a slate box and currently a stacked ply with graduated cut outs through the layers and I prefer it to the others. Easy enough to DIY too.
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I was wondering about the design of those plinths with very little room around the motor, can you shine any light in that?
 
I suppose it makes it less of an echo chamber, and adds mass, but @divedeepdog is a prolific plinth maker so he will probably understand and be able to explain how it all works better than me.
 
I'm thinking DAS acoustics black plinth, but they don;t answer, so sod em, also like the look of the ply ones, and a new mat, thanks.
 
In the bigger solid plinths do you still screw the nuts onto the mounting bolts? The plinth looks too big for that, but I ain't the underneath of one yet.
 
Frankiesays said:
In the bigger solid plinths do you still screw the nuts onto the mounting bolts? The plinth looks too big for that, but I ain't the underneath of one yet.
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I do, but gently. The plinth I have came from a fellow Audio Abattoirist whos bolts must have been longer than mine, so the use of Forstner bit was required...

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Frankiesays said:
In my current sme plinth, screwing the bolts down meant the difference between a high pitched hum and almost silence.
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I found the same, it’s a big old motor so some vibes are almost inevitable. I used some thicker rubber washers that helped too.
 
A few pointers that may help......

I notice the decoupling spring suspension has been removed from the top plate of the SME plinth. First thing I’d check is that there is some other form of decoupling between top plate and plinth. SMD at Peak Hifi have sets of decoupling domes which should work well.

Also make sure the mains cable isn’t interfering with the motor suspension. I’ve found effective dressing of the mains in any type of plinth essential to 301/401 performance - especially in terms of pitch accuracy and vibration transference.

Usually the feet of the SME plinth are fixed to a flimsy base. Remove the flimsy base (it’s as safe without as an open type plinth) and fix rubber feet to the plinth itself and not the base.

SMD, Loricraft, Layers of Beauty plinths are all excellent.
 
I've got mine in a Loricraft skeletal plinth, but I guess these are not available anymore. I found that mine worked fine straight from the get go. I did replace the mat with one of Loricraft's cork mats, but I haven't compared it to an original TBH. Mine is extremely quiet, no mods, just a service from Loricraft. For more bucks, you can get an electronic motor controller, this would enable you to ditch the eddy current brake and would reduce the noise floor even further, but personally, I would ditch the plinth you currently have and go for a simpler solution; eBay is full of 410 plinths for around £100. Some experimentation with the feet/ mounting arrangement would be good too.
 
Graham H said:
A few pointers that may help......

I notice the decoupling spring suspension has been removed from the top plate of the SME plinth. First thing I’d check is that there is some other form of decoupling between top plate and plinth. SMD at Peak Hifi have sets of decoupling domes which should work well.

Also make sure the mains cable isn’t interfering with the motor suspension. I’ve found effective dressing of the mains in any type of plinth essential to 301/401 performance - especially in terms of pitch accuracy and vibration transference.

Usually the feet of the SME plinth are fixed to a flimsy base. Remove the flimsy base (it’s as safe without as an open type plinth) and fix rubber feet to the plinth itself and not the base.

SMD, Loricraft, Layers of Beauty plinths are all excellent.
Click to expand...
The top of the SME plinth has been lead lined - it is heavy, and i have it resting on 8 semi spheres, so 4 whole balls of rubber - proper hifi semi spheres.
 
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