Lenco GL75 recommissioning

[Tony L]

Given they are pretty easy to swap over I’d try both and pick whichever sound better. The original Lenco V-blocks were a fairly compliant rubber, about the feel of a hard pencil eraser IIRC. The area I’d worry the most about a Lenco arm is the lateral bearing races, they are pretty crude and open to the elements so likely have considerable stiction by now. Whatever you do I’d only consider low compliance carts with fairly high tracking weights in this arm, AT95E, Shure M44-7, DL103 etc. It is a very high-mass arm.

 

[foxwelljsly]

Given they are pretty easy to swap over I’d try both and pick whichever sound better. The original Lenco V-blocks were a fairly compliant rubber, about the feel of a hard pencil eraser IIRC. The area I’d worry the most about a Lenco arm is the lateral bearing races, they are pretty crude and open to the elements so likely have considerable stiction by now. Whatever you do I’d only consider low compliance carts with fairly high tracking weights in this arm, AT95E, Shure M44-7, DL103 etc. It is a very high-mass arm.

TBH, new V blocks is as far as I'm prepared to go on the Lenco arm, any more trouble and I'll be looking for a new arm. I may try swapping them when I have the deck apart to service the motor. The cart remains the Shure M75 it came with (no-name 3.0mil mono for 78's, no name 1.0 mil mono for mono and a Jico Nude Hyperelliptical for stereo).

Next job is to diagnose and remedy the motor noise being transmitted through the idler wheel. It's not intrusive, but I'd like it as close to silent as I can get it.

 

[Tony L]

Next job is to diagnose and remedy the motor noise being transmitted through the idler wheel.

I’m sure you have, but worth mentioning anyway… you have released the two red transit bolts fully?!

 

[foxwelljsly]

I’m sure you have, but worth mentioning anyway… you have released the two red transit bolts fully?!

Yep - mulling over taking them out.

They were not tightened when I first had the platter off, so not during it's journey to my record room - might that be a cause for concern?

 

[Tony L]

A full strip and clean of the motor will likely fix it. A really heavy drop in transit can apparently knock the motor spindle out of alignment, but hopefully that isn’t the case here. I don’t think the transit bolts would save that anyway. It is likely fine, most are. It certainly shouldn’t be noisy. Of all the classic idler decks the Lenco is about the simplest and easiest to get working quietly.

What type of idler is fitted? If the plastic type with rubber ‘o’ ring that’s your rumble right there. They are terrible. Just replace with one of the later two or five-hole metal ones or a modern third-party one.

 

[foxwelljsly]

A full strip and clean of the motor will likely fix it. A really heavy drop in transit can apparently knock the motor spindle out of alignment, but hopefully that isn’t the case here. I don’t think the transit bolts would save that anyway. It is likely fine, most are. It certainly shouldn’t be noisy. Of all the classic idler decks the Lenco is about the simplest and easiest to get working quietly.

What type of idler is fitted? If the plastic type with rubber ‘o’ ring that’s your rumble right there. They are terrible. Just replace with one of the later two or five-hole metal ones or a modern third-party one.

It's a five hole metal idler wheel and the rubber and bearing look and feel spot on. The audible noise appears to be motor vibration amplified by the idler wheel and armature.

 

[foxwelljsly]

After a dust, new stylus, v blocks, spring base plate and tatty lid removed:

 

[foxwelljsly]

Between the deck and plinth are little rubber grommets. Is there any value in removing these?

Also, might there be value in adding mass to the plinth? If so, how is this best done?

 

[paulfromcamden]

Between the deck and plinth are little rubber grommets. Is there any value in removing these?

Also, might there be value in adding mass to the plinth? If so, how is this best done?

I think the perceived wisdom is to remove the grommets if you have a high mass plinth, leave them in the original plinth.

 

[Tony L]

Looks like a nice clean example. At this stage focus on getting it running quietly. It will never be ‘belt drive quiet’, but it sounds like something is wrong at present. Strip, clean and re-lube the motorpaying careful attention to the sprung nose-spring thingy (there should be a fair bit of movement here, but well damped). Pay attention to the motor springing, including which springs go where, IIRC there are two lengths. Also pay attention to the motor wiring and that it isn’t impeding the way the motor hangs, the drive shaft should feel very well sprung. Obviously be careful of mains voltage in there while you work, but running the motor outside of the deck can tell you a lot when it comes to the nose-bearing spring etc. Quietest is best, obviously. It will also give you a good indication of motor condition. You should be able to get it running very quietly if it is in good condition.

 

[Helen Bach]

I have fitted some soft silicon v blocks from some random on e bay, but I now have a pair of David's harder cnc'd v blocks - is it worth swapping them?

Between the deck and plinth are little rubber grommets. Is there any value in removing these?

Also, might there be value in adding mass to the plinth? If so, how is this best done?

The silicone rubber v-blocks will not help. They are far too soft, and will not support the arm well enough. Best advice is to use another arm, though. Just adding mass to the plinth will do very little, as mass doesn't damp, in fact it stores vibrations, and only damps according to the material/s involved. Transfer of the vibrations to the plinth will not be great, either, as the mechanical impedance mismatch will result in the vibrations being reflected at the interface. And be aware that adding thickness to the plinth will result in the resonance frequency increasing!

 

[foxwelljsly]

Now been using this with LPs for a few days. Pretty much stock, apart from the rubbish baseplate and springs being removed and some cnc’d v blocks in the L75 tonearm. I am using the stock M75 EJ Type 2 Cart with a new £33 stylus and a Rothwell Simplex phono stage. Total cost about an hour and £108, plus £48 for a shiny new lid and hinges and £125 for the phono stage.

My other turntable is an Acoustic signature Challenger with a Roksan Nima unipivot tonearm, an Audio Technica 33 PTG II MC cart and an Arkless transimpedance MC phono stage, so about £5k in todays money.

I am genuinely shocked at how good records sound on this thrift store turntable and how marginally better records sound on my other turntable. The bass, in particular, on the GL75 has a lovely richness to it, with acoustic instruments having a lovely stentorian woodiness to them.

A Jelco arm and collar is on it’s way and after that I plan a Jico SAS stylus for the M75.

 

[paulfromcamden]

stentorian

The Wrath of the Stentorians is one of my all time favourite Tom Baker episodes of Dr Who.

 

[Toaster]

Although the stock arms are decent, you should find that the Jelco is a significant improvement. I usually have the Isokinetik version of the 10" SA750E on my modified deck. Presently it has my 10" Blackbird on it, which is very nice indeed.

 

[Viola]

My first proper turntable after the SP 25.

Ah yes, the Garrard SP25 mkIV. This was what many of use queued up for in Lasky's on a Saturday afternoon when the GL75 was just a bit too expensive.