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AudioLapDance 8th January 2013 09:58 PM

Great entry table Technics SL-220: upgrade paths?
 
1 Attachment(s)
Scored a good condition 220 locally for $20 and, after a speed pot cleaning and new belt, she’s up and soundin’ sweet!

From:
Technics SL-220 - AudioKarma.org Home Audio Stereo Discussion Forums
and
Technics SL-220 checklist? - AudioKarma.org Home Audio Stereo Discussion Forums
I’ve gathered some info:

Plastic but TNRC (Technics non-resonant compound)
FG Servo DC motor (less hum)
Similar arm to SL-1200 (same/similar geometry, armtube and headshell and good bearings)

To make servicing even easier, the service manual is available at Vinyl Engine!
Technics SL-220 Owners Manual, Service Manual, Schematics, Free Download | Vinyl Engine

Here are the specs from the manual:

Attachment 322470

A few cartridges were mentioned:

Grado Prestige line ($80-250)
Audio-Technica AT440MLa ($170), AT120E/t ($100), AT13E2 ($60)
Ortofon FF15E MKII ($)
Shure M91ED ($70) and Shure M97xe ($90)

A good first upgrade would be the cartridge--it came with a Stanton L720.
I’m new to vinyl: how do I match the cart to the arm?

One guy says that the SL-220/230 “works especially well with Grado cartridges. The FG servo DC motor doesn't induce hum and the arm's effective mass is a good match to the compliance of the Grado Prestige line.”

The SL-220 arm is 230mm and 13g. The manual suggests a cart between 5.5 and 8.5g. The Grado Green/Black1 and Red/Blue1 have a weight of 5.5g and a compliance of 20. Is there more to 'compliance' than this?

Any other suggestions?

Cheers,
Jeff

benb 9th January 2013 06:32 AM

Those Technics speed control pots seem to always be flaky. I wonder if it has DC going through it or what. I can imagine making a "lightspeed" type LED/CDS cell speed control circuit to replace the pot, but I wonder about drift.

I have a SL-1300 (either a thrift store or yard sale buy, it's been so long I forget which) with an AT440MLa that I like. I also have a Grado Blue and I like the AT MUCH better. Amazon had it on sale a couple years ago for $99 which was a bargain.

The compliance is "springiness" of the stylus assembly. It and the effective mass of the tonearm/cartridge combination determine the resonant frequency of the cartridge-arm system. 10Hz is supposed to be ideal. This resonance gets activated anytime there's a bump or sharp warp in the record, so it's mainly a problem with non-flat records.

AudioLapDance 12th January 2013 06:04 PM

Pics of guts
 
4 Attachment(s)
Here are some pics of the guts:

Underside
Attachment 323393

Speed pots
Attachment 323394

Freq Gen PCB bottom
Attachment 323395

Freq Gen PCB top
Attachment 323396

AudioLapDance 12th January 2013 06:13 PM

4 Attachment(s)
More!

Auto return gears
Attachment 323397

Strobe
Attachment 323398

Under arm, anti-skate
Attachment 323399

FG servo DC motor
Attachment 323400

sreten 12th January 2013 06:28 PM

Hi,

Grado's are alright if you don't mind the top octave missing.

Three great budget buys are :
Ed Saunders Red Ed Cartridge
and
Amazon.com: at92ecd

The former match your arm a little better than the latter.

rgds, sreten.

AudioLapDance 12th January 2013 09:16 PM

Here's the specs for the Red Ed Elliptical

Frequency Response 20Hz-20kHz±3dB
Channel Balance 2dB @ 1kHz
Channel Separation 20dB @ 1kHz
Sensitivity 5mV±2dB, 1kHz @ 5 cm/sec
Static Compliance 16mm/N
Equivalent tip mass 0.7 mg
Vertical Tracking Angle 26°
Stylus Radius Elliptical .007X.003
Load Resistance 47,000 Ohm
Cartridge Weight 4.2g


The SL-220 arm is 230mm and 13g. The manual suggests a cart between 5.5 and 8.5g

The Red Ed is 4.2g is that too light? Does the Red Ed Static Compliance of 16mm/N play into this?

I can't find the weight of the at92ecd?!?

Thanks for the help,
Jeff

sreten 12th January 2013 09:38 PM

Hi,

Both will be fine with your arm, but the RedEd's will match a little better.

Basically you add cartridge mass to the arm effective mass and this
number combined with the cartridge compliance determines the
resonant frequency of the arm/cartridge, should be ~ 10Hz.

The technics arm with original headshell is quite lightweight, compared
to other similar looking arms, and worth $20 on its own, compared to
similar looking others, its not too bad in absolute terms, in fact the
nice original headshell is worth around $20 on its own.

rgds, sreten.

AudioLapDance 8th February 2013 06:31 PM

2 Attachment(s)
Quote:

Originally Posted by sreten (Post 3322994)
...
Basically you add cartridge mass to the arm effective mass and this
number combined with the cartridge compliance determines the
resonant frequency of the arm/cartridge, should be ~ 10Hz.
...

Hi Sreten, thanks you've put me on a little journey!

I made a spreadsheet to calc resonant frequency (of a few carts I'm considering: Red Ed, M97eX, AT440MLa, 2M Red, Grado[green, black, red, blue], and the OM5E+stylus10 that I have):

Attachment 329184

Attachment 329182

The SL-220 arm is 230mm and 13g. The manual suggests a cart between 5.5 and 8.5g. Headshell = 9g , Arm = 13 - 9 = 4 g



The resonant frequency:

Fr= 1000 / [2 pi * sqrt(M * C)]

where, pi = 3.14 (approx), M = total effective mass in gm of the arm plus cartridge, and C = compliance of the cartridge in um/mN (um is micrometer and mN is milliNewton; um/MN is the same unit as micro cm/Dyne).

I understand I should aim for about 10 Hz (between the audio 20 Hz and the resonant freq of the turntable suspension ~1 Hz). I was using 16 as the compliance before (which gave close to 10 Hz!) then I realized I have to use the dynamic compliance not the static compliance. I emailed Ed (what a fascinating guy!) and he said:

They do not list the dynamic. That is not really a meaningful spec. It would be around 25 however.

So with the dynamic compliance of 25, the resonant freq is 7.7Hz
A little less than the 'ideal' 10Hz.

Hmmm ...


Thanks for the help,
Cheers,
Jeff

AudioLapDance 8th February 2013 07:47 PM

I also reverse calced the carts!

5.5g to 8.5g as recommended in the manual:

5.5g, dyn comp~14
8.5g, dyn comp~12

(assuming linear type relationship: 7g, dyn comp~13?)

for Fr~10z

:cool:

nezbleu 12th February 2013 12:57 AM

Get some Duxseal and use it to cove the corners on the underside of the base, and fill some of those gaps. Just be careful not to gum up the auto mechanism. That will add mass and dampen resonances in the plinth, it helps a bit.


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