The Bolt Mod
Posted by: trickytree on 15 November 2003
Have just fimished playing a few records after completing the bolt mod. If ever there was a mod/upgrade to the LP12 that could be recomended to everyone with the certainty that no-one will be disapointed, then this is it.
Surface noise is greatly reduced, and with that comes a wealth of low level information that was hidden without the 'bolt'. Dynamic range is increased with the benifit (to me) of being able to reduce the volume level. Notes stop and start faster, with obvious gains in PRaT.
All this is done with no perceived change in tonal balance. As I said at the begining, in my opinion there are no downsides to this mod. If you have a LP12, then just do it.
Paul.
Surface noise is greatly reduced, and with that comes a wealth of low level information that was hidden without the 'bolt'. Dynamic range is increased with the benifit (to me) of being able to reduce the volume level. Notes stop and start faster, with obvious gains in PRaT.
All this is done with no perceived change in tonal balance. As I said at the begining, in my opinion there are no downsides to this mod. If you have a LP12, then just do it.
Paul.
Hi Nick.
All the hardware came from B&Q. The flange nuts, (they call them T-Nuts) cost £1.30 for four. I used 6mm as they had sold out of 5mm, must be a lot of folk doing the mod!! 6x60mm machine screws and nuts cost the same as do packs of washers.
There was a good thread on Pink Fish detailing how to do the mod but the page seems to have gone AWOL.LOOK HERE
Unfortunatly I dont have a digital camera, so have RICHARDS PHOTO'S handy for referance.
Heres how I did mine. Unplug the mains, remove the baseboard if fitted. Secure the deck on its side, motor side down, with whatever means you have. I clamped mine to a workmate. Drill a hole in the corner brace the same diameter as your bolt, 6mm in my case. Be carefull not to damage the top plate when you break through.
If you look at Richards photo he has removed the tangs from the flange nut, I bent mine flat with a pair of pliers. You can bond the nut to a washer if you wish. I bought some large diameter repair washers for this purpose but they proved to be to big and cumbersome so I glued the nut directly to the top plate.
Key the back of the nut with some coarse sand paper and clean thouroghly with Isopropyl. Do the same to the underside of the top plate. This will help give the glue a good bond.
Now comes the tricky part!
Insert the bolt in the corner brace so that you can fit the nut to the end of the bolt. Put your chosen adhesive on the back of the nut and screw it onto the bolt, making sure the bolt does'nt protrude through the nut. (I used Araldite as I had some. JB Weld would probably be better and is apparently available from Halfords). I held the nut with some long nosed pliers to get it onto the end of the bolt. Thats the tricky part over with. Now all you have to do is push the bolt through the corner brace untill the nut makes contact with the top plate. Dont push to hard as you will squeeze out all the adhesive, Hold in position with a blob of Blue-Tack or whatever and leave 24 hours to set.
Remove the bolt and shorten it so that it does not bottom out in the flange nut when screwed down to the corner brace. Pop on a washer and place through the hole in the corner brace. Before screwing into the top plate, insert another washer and a nut. Screw the bolt into the flange nut and nip it up, finger tight and a further quarter turn seemed OK for me. Tighten the remaining nut down onto the corner brace and the job is done. The whole idea is to connect the top plate near the motor mount to the plinth. I suppose you could try tightening or loosening the bolt slightly if you wish, it may make a difference. I doubt you will want to try, you'll be to busy playing records!
One thing to watch out for is that you dont use to much adhesive on the flange nut, if it runs onto the bolt while setting you wont be able to remove the bolt which would be a little anoying to say the least!
Paul.
All the hardware came from B&Q. The flange nuts, (they call them T-Nuts) cost £1.30 for four. I used 6mm as they had sold out of 5mm, must be a lot of folk doing the mod!! 6x60mm machine screws and nuts cost the same as do packs of washers.
There was a good thread on Pink Fish detailing how to do the mod but the page seems to have gone AWOL.LOOK HERE
Unfortunatly I dont have a digital camera, so have RICHARDS PHOTO'S handy for referance.
Heres how I did mine. Unplug the mains, remove the baseboard if fitted. Secure the deck on its side, motor side down, with whatever means you have. I clamped mine to a workmate. Drill a hole in the corner brace the same diameter as your bolt, 6mm in my case. Be carefull not to damage the top plate when you break through.
If you look at Richards photo he has removed the tangs from the flange nut, I bent mine flat with a pair of pliers. You can bond the nut to a washer if you wish. I bought some large diameter repair washers for this purpose but they proved to be to big and cumbersome so I glued the nut directly to the top plate.
Key the back of the nut with some coarse sand paper and clean thouroghly with Isopropyl. Do the same to the underside of the top plate. This will help give the glue a good bond.
Now comes the tricky part!
Insert the bolt in the corner brace so that you can fit the nut to the end of the bolt. Put your chosen adhesive on the back of the nut and screw it onto the bolt, making sure the bolt does'nt protrude through the nut. (I used Araldite as I had some. JB Weld would probably be better and is apparently available from Halfords). I held the nut with some long nosed pliers to get it onto the end of the bolt. Thats the tricky part over with. Now all you have to do is push the bolt through the corner brace untill the nut makes contact with the top plate. Dont push to hard as you will squeeze out all the adhesive, Hold in position with a blob of Blue-Tack or whatever and leave 24 hours to set.Remove the bolt and shorten it so that it does not bottom out in the flange nut when screwed down to the corner brace. Pop on a washer and place through the hole in the corner brace. Before screwing into the top plate, insert another washer and a nut. Screw the bolt into the flange nut and nip it up, finger tight and a further quarter turn seemed OK for me. Tighten the remaining nut down onto the corner brace and the job is done. The whole idea is to connect the top plate near the motor mount to the plinth. I suppose you could try tightening or loosening the bolt slightly if you wish, it may make a difference. I doubt you will want to try, you'll be to busy playing records!
One thing to watch out for is that you dont use to much adhesive on the flange nut, if it runs onto the bolt while setting you wont be able to remove the bolt which would be a little anoying to say the least!
Paul.
Andy,
Your link is not working ??
Anyway, this looks like a mod I have to try, nothing much to lose as my LP12 only cost me £250 S/H (with an Ittok).
By the way, I see lots and lots of mods to the power supplies on LP12's but it strikes me that there must be a better way. was'nt there some decks in the 80's that used a type of induction 'motor', i.e. no motor at all, just a changeing magnetic field directly driving the platter.
Forgive the vagueness but I only have a vague idea of the principle, but surely getting rid of the motor is the key ???, I'm sure there is enough expertise on this forum to come up with a really radical improvement on this basically old design.
Mike
Your link is not working ??
Anyway, this looks like a mod I have to try, nothing much to lose as my LP12 only cost me £250 S/H (with an Ittok).
By the way, I see lots and lots of mods to the power supplies on LP12's but it strikes me that there must be a better way. was'nt there some decks in the 80's that used a type of induction 'motor', i.e. no motor at all, just a changeing magnetic field directly driving the platter.
Forgive the vagueness but I only have a vague idea of the principle, but surely getting rid of the motor is the key ???, I'm sure there is enough expertise on this forum to come up with a really radical improvement on this basically old design.
Mike
Link fixed (it was a bracket thing)...
My view is big magnetic fields are bad news near sensitive transducers giving out sub-microvolt signal levels
A.
My view is big magnetic fields are bad news near sensitive transducers giving out sub-microvolt signal levels
A.
quote:
Originally posted by MJSM:
By the way, I see lots and lots of mods to the power supplies on LP12's but it strikes me that there must be a better way. wasn't there some decks in the 80's that used a type of induction 'motor', i.e. no motor at all, just a changing magnetic field directly driving the platter.
Forgive the vagueness but I only have a vague idea of the principle, but surely getting rid of the motor is the key ???, I'm sure there is enough expertise on this forum to come up with a really radical improvement on this basically old design.
Mike
Are you talking about direct drive turntables? The ones that are never going at the right speed and constantly hunting up and down looking for the right speed? Slurring the music in the LP groove?
The Linn was supposed to put an end to all that! But then they got too clever and started building power supplies that made them constantly hunt up and down looking for the right speed.
Nime
Everyone has the right to be wrong.
quote:
Originally posted by dave simpson:
http://www.areyoulocal.com/PhotoShow.asp?Title=Doing%20the%20bolt&Counter=1&Keyword_1=bolt
Try the link above Ken.
regards,
dave
still so pictures, just the text describing the pictures.
enjoy
ken
quote:
Originally posted by ken c:quote:
Originally posted by dave simpson:
http://www.areyoulocal.com/PhotoShow.asp?Title=Doing%20the%20bolt&Counter=1&Keyword_1=bolt
Try the link above Ken.
regards,
dave
still so pictures, just the text describing the pictures.
enjoy
ken
Ken - are you still having problems? If so, drop me an email and I'll mail you the pics.
richard [at] hallman.co.uk
quote:
Originally posted by Andrew L. Weekes:
Link fixed (it was a bracket thing)...
My view is big magnetic fields are bad news near sensitive transducers giving out sub-microvolt signal levels
A.
Andy,
I get where your coming from, but I know that some manufacturers perfected this technique (B&O for one) so it is technically achievable, and theoretically vibration free (although who knows what other jiggery-pokery they had to install to filter put those nasty magnetic waves).
I still think it is the way to go though, and am surprised that Linn did'nt find a better way quite honestly, a motor an belt is pretty old technology, and the vibrations from the motor appear to be a constant source of headache.
Come on Andy, I think some research and development is called for here, just can't think what you would call the thing - the ALW-Linddo maybe ???
Mike
