DIY TT and Amps

[jervill]

Hello All,

Just posted once before. Anyway these are my projects made possible in part by vinylengine's resources.
This is my first TT build utilising the Lenco Gl75 on a ptp5. The plinth is made of three layers of perspex. Two by 10mm clear sheets sandwiching a 5mm red shee bolted together. The arm is the 12" conversion of a 3009 s2 improved using a keeper-darren kit (eBay). This was the subject of my only other post. The cartridge in the interim is an ortofon arkiv low compliance MM. Thanks to all you guys.





(This is the second attempt on the plinth)

These are the amps that will power it. All based on JE Labs circuits (2a3dx and FF phono pre).
All projects completed this year hence the interim cartridge choice, my account is tapped out!




Regards all and thanks again.

[duficity]

Very,very cool. How does it sound?

[jervill]

Hi,

Thanks. At the moment I'm still evaluating the settings for the turntable using different protractors and experimenting with the 2-4g range for the tracking force. Initial impressions are good. I must admit that at the recommended 3g TF for this cartridge the sound is quite catchy and intense which I like. Whether this will become tiresome I'm yet to see. 2g TF, although picks up less of the motor and gives a more laid back presentation, is also a touch more sibilant. I have it tracking at 2.7g for now.

I've not paired it with the valve amps yet. I'm using my Denon AV receiver and Cambridge Audio 640p for evaluation. It would seem that the motor rumble will be below that of the valve phono stage hum so will not present an issue I don't think. As it is, I have to be 3" from the speaker to hear the motor being picked up by the arm. Getting the counter-weights as close to the yoke as possible seems to have helped.

Compared to the original, the PTP has raised the game for sure.

[duficity]

does the cartridge really require such high tracking force?

[Blue Angel]

Errr...cough...cough...it seems I've met my match

Very nice and tasteful design. My compliments.

Regarding the hum. Have you tried re-routing phone and mains cables? I have recently re-wired a replica 3012 arm and included with the 4X channel wires, also a 5th earth wire which goes all the way to the headshell connector, as most of my Micro arms have this arrangement.

Did you include any arm damping material as per the original SME 3012 and others?

ba

[jervill]

Hi guys,

Thanks for the kind words.

The tracking force probably doesn't need to be that heavy. It's a dj cart though so I've started from its recommended TF and am working down from there. The sibilance at 2g seems to be calming down as the cart is used. That is the target weight. Adjusting the idler arm and damping it seems to have helped the lighter tracking when I've rechecked, don't know how that works but is my subjective observation. Also, the removal of the rubber washer between cartridge and socket.

The arm itself has little hum although I've noticed that if I touch the arm, the hum is reduced even more. The input sockets are DIY phono conversions and I've followed the wiring instructions from the original SME conversion kit. I'm now thinking of running a seperate earth wire to the phono stage ground post from the arm assembly. I'll see as I think this will create two paths to ground which may loop. As is, it's not intrusive but any ideas for refinements are welcome.

I've not used any damping on the arm as I was unaware of this detail. Is it critical?
I'm also not using the anti skate as the arm seems to be fine without it. Any opinions on that?

The hum I refer to is in the circuitry of the phono stage itself. I'm working on that but is maybe from the drawback of the lay-out I chose. But, I've managed improvements so maybe there's more to squeeze.

I wanted to ask, where in the headshell socket do you connect an earth wire?

[dtut]

Very nicely and attractively done, especially the TT. Congratulations.

Doug Tuthill

[jervill]

dtut,

Thank you for your comment. It looks better on the photos...

[cafe latte]

Hi,

Thanks. At the moment I'm still evaluating the settings for the turntable using different protractors and experimenting with the 2-4g range for the tracking force. Initial impressions are good. I must admit that at the recommended 3g TF for this cartridge the sound is quite catchy and intense which I like. Whether this will become tiresome I'm yet to see. 2g TF, although picks up less of the motor and gives a more laid back presentation, is also a touch more sibilant. I have it tracking at 2.7g for now.

I've not paired it with the valve amps yet. I'm using my Denon AV receiver and Cambridge Audio 640p for evaluation. It would seem that the motor rumble will be below that of the valve phono stage hum so will not present an issue I don't think. As it is, I have to be 3" from the speaker to hear the motor being picked up by the arm. Getting the counter-weights as close to the yoke as possible seems to have helped.

Compared to the original, the PTP has raised the game for sure.

You should not be getting ANY rumble from an idler drive. Things to look at is what lube are you using in the main bearing, what condition is the idler wheel in and the idler bearing?
The rubbers that isolate the motor, what is there condition and has the motor been stripped and bearings cleaned and lubed?
Also the valve phono stage really should not hum at all, my feeling is there is some sort of earth loop maybe.
Regards
CL

[jervill]

Hi,

Thanks. At the moment I'm still evaluating the settings for the turntable using different protractors and experimenting with the 2-4g range for the tracking force. Initial impressions are good. I must admit that at the recommended 3g TF for this cartridge the sound is quite catchy and intense which I like. Whether this will become tiresome I'm yet to see. 2g TF, although picks up less of the motor and gives a more laid back presentation, is also a touch more sibilant. I have it tracking at 2.7g for now.

I've not paired it with the valve amps yet. I'm using my Denon AV receiver and Cambridge Audio 640p for evaluation. It would seem that the motor rumble will be below that of the valve phono stage hum so will not present an issue I don't think. As it is, I have to be 3" from the speaker to hear the motor being picked up by the arm. Getting the counter-weights as close to the yoke as possible seems to have helped.

Compared to the original, the PTP has raised the game for sure.

You should not be getting ANY rumble from an idler drive. Things to look at is what lube are you using in the main bearing, what condition is the idler wheel in and the idler bearing?
The rubbers that isolate the motor, what is there condition and has the motor been stripped and bearings cleaned and lubed?
Also the valve phono stage really should not hum at all, my feeling is there is some sort of earth loop maybe.
Regards
CL

Hi,

Thanks for your interest. The motor and bearings have all been stripped and cleaned. I used grease for their main bearings and then oil on top of the main bearing and at the end of the drive shaft. I've reduced the noise from the motor by loosening the suspension further and also by loosening the idler arm from the slider and damping it with blu-tack. Unfortunately, the motor I have seems to be noisier than can be got from other examples. It was like this from stock and at least I managed to improve it by a bit of lube and recentering the drive shaft. Further noise is coming from the spindle but not intrusive. This is probably from the notch I saw on the bearing when I stripped it, past accident perhaps. I'll replace that in the future. Now at my normal listening level, there is no audible motor noise from the listening position through the speakers. (It's there closer though)

I've been working on the phono stage in the last couple of days. I've managed to get the left channel dead quiet and reduce the hum on the right by reheating all the solder joints and re routing the b+ supply. I'm trying to find the source of this hum. It's not from the valves nor the line stage section which is quiet. Any ideas where to check? Its attenuated by the pot if that should give me a clue.

The 6mv output of the cartridge means that my phono stage is turned down which means the hum is not audible at normal listening level. (Still want to sort out the hum though for future set ups.) Question for the more experienced and tech minded, with the 2m red at 5.5mv output I can have the phono pot fully open, with the ortofon arkiv at 6mv it starts to distort past the 12 o'clock position. .5mv difference in output makes that much difference or there are other considerations?

After much fiddling with the arm and cartridge set up, I have it tracking at 3g with minimum anti skate. This produces the best all round sound and compromise for playing my predominantly charity shop and hand me down vinyls. Lower Vtf causes mistracking and other issues on the more ragged examples. Some lps I have which I rarely listened too, as I found too noisy on the other cartridges I have on another table, are quite playable on the arkiv. I suppose the bigger needle riding higher on the groove helps. I'm not now in a rush to change it in fact I'm not now dismissive about dj carts and their usefulness for certain hifi applications, I'm getting to enjoy my 'write offs' again. (My mint lps though are waiting to have more spin time on the dl103r I'm saving for...)