Pye, Black Box Mk1 1954, cartridge.
 

Hi all.

I was surprised to find the cartridge appeared to work? when first tried. I think the overall volume is down a bit though. If the amp is driven externally it does sound very good, all the usual caps have been changed.

Before I look for a replacement cartridge can anyone tell me if its a low, med, or high output cartridge. See attached images. I'm happy playing just mono records and want to keep the original style of turnover cartridge. Colin

Re: Pye, Black Box Mk1 1954, cartridge.
 

This is a medium output Acos Hi-G cartridge. You can buy a near equivalent Mono-only LP/78 turnover cartridge for £38-00. But just remember to keep your Stereo LPs at a safe distance.

Re: Pye, Black Box Mk1 1954, cartridge.
 

I have now spotted the HI-G entry in Ben's sticky thread above & the output is stated to be "1V?" I guess this will make it a high output cartridge. This does somewhat tie up with the fact that when I tested just the amp, it seemed to need more volts on the input than I imagined it would. Colin

Re: Pye, Black Box Mk1 1954, cartridge.
 

It depends on which version of the Hi-G cartridge it is. Certainly 1.0V will overload the first triode stage. I remember ACOS made the HGP37-1C and then the HGP39 type. What is in yours? The type number is on the other side to that in your photo. I don't recall that a high-output cartridge was never specified for these.

Re: Pye, Black Box Mk1 1954, cartridge.
 

My first BBH Black Box had a cream coloured Acos Hi-G, apparently from new.

What's the significance of the body colour, Edward?

Re: Pye, Black Box Mk1 1954, cartridge.
 

Thanks for your replies.
Both sides are identical, there is no part Number on either side. Just Acos, HI-G, & Made in England.

Re: Pye, Black Box Mk1 1954, cartridge.
 

Yes, the Hi-G was made in both Cream and Brown body colours. Trouble is, it's such a long time since I've encountered one of these I can't accurately remember which was which. I have a vague recollection of the cream being high and the brown as the medium output version. They were certainly "replace on sight" when we were mass fitting Stereo-Compatibles in the mid 1960s. The input sensisitivity of the first generation (2 x EL42s) of BBs was c.300mV, which would rule out the use of a high output cartridge - yet this conflict with Nickthedentist's experience.....

Re: Pye, Black Box Mk1 1954, cartridge.
 

Pye didn't help by not even mentioning the cartridges in their service documentation.
A bit of cross referencing here may help: https://www.vintage-radio.net/forum/...2&postcount=10

Re: Pye, Black Box Mk1 1954, cartridge.
 

I followed the link thanks. Mine looks like a HGP37-1, that was cross referenced with a GP67-2 which is shown as a high output? does the "-1" mean medium & "-2" high or is the "H" high perhaps?.

I gather that the rule of thumb is that a high output cartridge is only for one valve amps? As the Black Box amp has a preamp a medium output cartridge should be ok?

The D.C. input impedance of my amp measures 800K, 20% low, I assume this is just due to the tolerance of the 1Meg volume pot. Perhaps I should follow this up in case C1 is leaky, this goes to the tap on the volume pot. Colin

Re: Pye, Black Box Mk1 1954, cartridge.
 

A medium output cartridge will be exactly what is needed. We bought in the UA6 decks from BSR with those Acos Hi-Gs pre-fitted. The single player versions used a Collaro AC54 3 speed deck with a (most excellent) Collaro Studio "O" cartridge pre-fitted - again a medium output type. Are you going to continue using the existing Acos given it still works or buy a new Mono or Stereo (used as Mono) cartridge?

Re: Pye, Black Box Mk1 1954, cartridge.
 

Thanks Edward.

My parents got hold of another for my younger brother a year or so after I got mine (they were being given away by friends who'd belatedly upgraded to stereo, this would have been mid-1970s), and this had a newish X5H fitted.

Re: Pye, Black Box Mk1 1954, cartridge.
 

Hi Edward. Although the cartridge is working I'm sure I should have more volume. I was thinking of getting a mono replacement, knowing I can't play stereo records. It's just deciding where to get it from. Colin

Re: Pye, Black Box Mk1 1954, cartridge.
 

More info.
With the cartridge unplugged from the amp, I just scoped the cartridge output whilst playing a Tremeloes 45rpm. With a 1Meg load from the scope. I had an average of 800 to 900 mV p to p. With loud passages topping around 1.4V. The arm is set to 8 grams.

Re: Pye, Black Box Mk1 1954, cartridge.
 

As I understand it the output from Cartridges is quoted in rms.
John

Re: Pye, Black Box Mk1 1954, cartridge.
 

With that kind of cartridge output you should be getting loads of volume! There may be a fault on the ampliier - possibly low HT? You can fit a Stereo cartridge to this that will allow you to play Stereo pressings safely (and with a lighter tracking weight) but in Mono of course.

Re: Pye, Black Box Mk1 1954, cartridge.
 

Although the cartridge seems to be giving enough output, I think a new cartridge is still needed anyway as the stylus (New) doesn't always sit vertically when looking from the tone arm end, this seems to be due to the suspension rubber being slightly offset.

I've changed the two coupling caps and the electrolytics and substituted the ECC83. The two EL42's are reasonably matched but are down on gain on my VCM, so I may have to change these. The H.T. reading is high if anything, C9 304V / C2 278V. I calculated the current through the output valves to be a total of 28mA by measuring the volts across R14, the service data is 16mA each valve. I have also measured most of the resistors, but not changed the Hunts caps.

Current plan is to fit a new cartridge anyway, then I will give the amp a more detailed look, probably changing the remaining caps.

Has anyone got any cartridge or suppliers to recommend, I defiantly want to retain the turnover function. Colin

Re: Pye, Black Box Mk1 1954, cartridge.
 

If you want to stick to the "turnover" type then go for the new-build BSR (clone) M TC8 at £38-00. This will give you groove-grinding Mono of course. It gives 400mV output as will load the ECC83 nicely. Be wary of the new-build Ronette (clone) turnover cartridges made in Italy.

Re: Pye, Black Box Mk1 1954, cartridge.
 

I have successfully used cartridges from Dansette.com.
John

Re: Pye, Black Box Mk1 1954, cartridge.
 

Thanks for your suggestions gents. Ill have a look at ordering a cartridge on Monday. Ill let you know how it all goes. (& perhaps the output valves) Colin

Re: Pye, Black Box Mk1 1954, cartridge.
 

As Edward confirms, nothing seems wrong with your HGP37-1 cartridge. You have a rare survivor. It’s most likely the amplifier gain that’s too low.

In my experience, somewhat low output valves don’t much affect the gain, though they may limit available maximum output power. So I’d be inclined to hold back on buying new EL42s.

If as you say you’ve already replaced the ‘prime suspect’ paper coupling capacitors, I’d be looking then for defective cathode decoupling electrolytics. If one goes open circuit, it introduces unwanted negative feedback into that valve stage, diminishing its gain. I’d also be checking actual resistor values in the overall negative feedback circuit. If they’ve drifted in value, there may be more negative feedback than the designer intended, thus reducing the overall amplifier gain.

Continuing the theme of negative feedback, you can always get more gain by deliberately increasing the value of the main feedback resistor from the output transformer to the relevant earlier valve stage. That may sound heretical and yes it will increase the amplifier distortion figure along with the rise in gain, but I’d be most surprised if you were to notice it compared with the other distortions in the record player overall.

Martin