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Just how good is the AR XA turntable ?

I have too much time on my hands, of late, hence the mental regurgitation.

Now that you mention the cable readings, I'm wondering what state the tonearm wiring harness connections are in below deck. The original external lead connections are made via slide connectors, whereas, the tonearm internal wiring is soldered on.

IMG_3595-L.jpg
 
Weren't shite and briny so to speak but positive feel after slightly nipping up and refitting. Measurements were the same before refitting as when connected to arm wire with head shell removed. Found some rg59 coax but not got any crimps so will cut the crimps off the original wire and solder on to new and see how we go.
Thanks, AP
 
Just thought to mention - The original wire pattern in the AR headshell was Red/Black right side, White /Green left side - easy to get this wrong compared with modern headshells.

The wires with the spades in the pic should be from right to left - grey wire -left ground, white wire - left signal, red wire - right signal, bronze wire - right ground, grey wire - chassis and top plate ground. The above pic appears to have the white soldered wire in the wrong place unless the photo is playing tricks or a different wire pattern has been adopted.
 
It appears to be the aftermath of an internal rewire.

AR XA internal wiring:
Lch +ve = yellow, pink, or blue
Lch -ve = green
Rch +ve = red
Rch -ve = copper​
 
Craig B said:
It appears to be the aftermath of an internal rewire.

AR XA internal wiring:
Lch +ve = yellow, pink, or blue
Lch -ve = green
Rch +ve = red
Rch -ve = copper​
Click to expand...

Yeah, the original wiring on an AR XA would use colored enameled wire, not vinyl insulated.
 
The rg59 wire seems to have improved clarity a little. Is there an ideal capacitance range for the g800e cartridge as the specs I found don't mention anything other than 47-100k ohm loading? The new wiring with the arm wires measures 120pF per channel. Not sure what the Ob3 phone stage has but guessing (dangerous I know) is likely 100pF.
 
It wasn't common to see a recommended capacitance range listed for popular models until the late 1960s. Shure Brothers, for example, didn't specify such for their existing models (including the pre-'improved' V15 Type II, 1966-1970) until the release of their 1968 catalogue. As you've discovered, Goldring only offered the kOhm loading.

There is an Ion Systems 'Standard Disc Input Cards Circuit Diagram' (issue 5, dated 27/7/90) available for download via hifiengine. Assuming this to be fundamentally the same circuit as yours, it should be possible to work out the input values.
 
Unfortunately I don't have internet access, only via works phone and can't download. Will have a look inside the amp.
I had read on one site some had found that at 375pF the g800e "comes alive" so may experiment. Thanks again, AP
 
A further (maybe stupid) question. Does the D110SE stylus fit the G800 cartridge or was there actually a G800se as it is not clear to me from what I've read? If it fits I will buy one of these from thakker. Cheers AP
 
a.palfreyman said:
Unfortunately I don't have internet access, only via works phone and can't download.
Click to expand...
Can you receive e-mail attachments? I could send the schematic to you, if you PM me your e-mail address.
a.palfreyman said:
Will have a look inside the amp.
I had read on one site some had found that at 375pF the g800e "comes alive" so may experiment.
Click to expand...
Note that there are ways to increase capacitive loading without modifying the phono cards.
a.palfreyman said:
Does the D110SE stylus fit the G800 cartridge or was there actually a G800se as it is not clear to me from what I've read? If it fits I will buy one of these from thakker. Cheers AP
Click to expand...
Yes, all three D110 tips are interchangeable on the same 800 series cartridge body.

I suspect that there is no difference between the Japan sourced Thakker D110E and D110SE, for the simple reason that JICO only list 110 and 110E, and Thakker's price is the same for both.

There were three Goldring 800 models as follows:
  1. 800 - bonded 0.5mil conical tip, original replacement stylus D110
  2. 800/E - bonded 0.3 x 0.7mil elliptical, original replacement stylus D110E
  3. 800/SE - bonded 0.3 x 0.7mil elliptical with higher static compliance of 35c.u.*, original replacement stylus D110SE
* According to Goldring's specifications, the compliance of 800 and 800/E were already in the medium range, with SE being an answer to the growing trend for even higher compliance values (and, hence, improved tracking ability) as exemplified by ADC, and later, Shure.
 
CraigB,
Once again you excel yourself!
Your points as above:
1- yes I can but not certain I could open it. I have a hifiengine a/c but couldn't download the pdf on this phone.
2- yes, I wasnt going to mod the cards, just find out what was fitted so I know what I have, then add accordingly to a y-lead or similar.
3- good to know and yes I spotted that D110E and SE were same price, just different stock codes.
4- thanks for the clarification regarding the original specs.
PM also sent.
Many thanks, AP
 
CraigB
PM received. Many thanks. Unfortunately can't view pdfs on this (company) phone. Anyway had the mm card out and it has positions on the inputs marked C401(and 'a') but nothing fitted there and certainly never been modified. Will see what I can cobble up.
 
You are welcome, AP.

The schematic covers both the MM and MC cards which appear to be the same circuit but for a few component changes. C401 isn't populated on the MM board, however, C402 is 150pF Cr, whereas, on the MC schematic this is marked as 'not fitted'.

Regardless, if you wish to try increasing capacitance, I'd assume 150pF plus the circa 120pF of your cable is putting you at roughly 270pF, for a start. Perhaps a tiny 100pF ceramic soldered into each phono plug (in series with the +ve pin) would be worth trying. As these are very cheap components, perhaps an assortment of values would be worthwhile experimenting with. In which case, a pair of RCA female to RCA male plugs (into which you try the various values) might make things easier; sort of like Rothwell attenuators but with capacitors in.
 
Well I tried 220pF across the inputs as I had some film caps available but couldn't hear any difference. I suspect part of the perceived "roll-off" is due to my main rig being quite "forward" sounding so I tried both LP and CD versions of 'Love Over Gold, Industrial Disease' via the Ob3 and phones (which is how I'd been listening) and despite the CD being slightly more open, there wasn't a lot in it. I re-capped the Obelisk 3 many years ago, but didn't do the mm card which has elcos for coupling so might be time to replace all the elcos and put film caps in for coupling duties. I also have a 'Black Cube' phono stage lurking so ought to give that a try too. Many thanks, AP
 
Ah, I didn't realize that the wee Black Cube was so user configurable.

In addition to the DIP switch settings, L/R gain jumpers, bass roll-off filter jumpers, and custom impedance plug connections, there appear to be 'free hardwire plug-in slots for additional impedances/capacitors' that will be 'put in parallel with all other switch-activated impedances/capacitors and the 47 kOhms/100 pF'.

Enjoy tweaking!
 
Re-capped the mm card of the Ob3 which has improved the clarity a bit (the background crackle is also slightly more obvious but that is a good sign) so will see how it settles in. Might also try some 0.22uF film bypass on the main 100uF caps which I replaced with Panasonic FRs.
 
I am envious of your efficiency, AP!

I also feel a bit dumb for daring to attempt teaching gran to suck eggs, as it were.
 
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Don't be, I should have been doing chores and got my comeuppance when 'er indoors got home. :eek: I have a bit of DIY electronics experience but I'm a electronics numpty really. I totally appreciate all the help I get from 'those in the know' on this site. Don't chastise yourself!
AP
 
The 100uF caps are for feedback so putting some film bypass across them has helped open the sound out somewhat. Also put some 0.33uF film caps on the supply adjacent to the input end of the circuit board (which is about 4" from the regs) and this has improved things further still. Sounds more open and dynamic now. Well pleased but had to put it away for a while as it has been living on the kitchen worktop (which is nice and solid with no footfall problems), much to 'er indoors displeasure!
 
Have you tried telling her that your fellow hobbyists are relying on you during these increasingly difficult lockdown days?

'Guilt, the gift that keeps on giving.' Erma Bombeck
 
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