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question on the BBC turntables : opinions !

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Re: question on the BBC turntables : opinions !

Postby Hugh Robjohns » Wed Nov 18, 2020 3:57 pm

:thumbup: :D Good Info.

I found this BBC report on the early RP2/6 just to give some idea of the typical nature of internal gubbins and construction!

I also found a BBC Engineering Design Information sheet which describes the new RP2/10:

BBC EDI wrote: New Design
RP2/10 Disk Reproducer for new installations and to supercede obsoloete equipm,ent as appropriate. Table top cabinet;floor standing adaptation using separate plinth. Single player 33/45/78 stereo and mono. Turntable, pickup arm and associated controls as RP2/9. Uses present standard Shure SC-35 cartridge; LP or 78 stylus assemblies.

Modular organisation for installation in bespoke desks and to permit choice of facilities with electronics to match.

Replaces RP2/6. Two units on plinths may replace RP 2/1 types. EDI No.10354 Refers.

For further information please contact W T Shelton, Room 302, Western House PABX LBH 3867.

This EDI is available here: http://www.bbceng.info/EDI%20Sheets/10358.pdf and gives brief descriptions of the earlier RP types.

And, much more importantly, the EDI 10354 mentioned above details the RP2/10 specifications and its optional facilities here: http://www.bbceng.info/EDI%20Sheets/10354.pdf

In particular, it mentions the outputs are via Hypertac connections...

I've also discovered there were at least four variants identified as the basic RP2/10, and then RP2/10B, C and D.

The basic RP2/10 was a 'minimum facilities' version for Continuity suits, but included the scratch filters, switched output attenuator, and groove location.

The -B version was a 'Full facilities' model for Radio and External Broadcasting with stereo/mono switching, RSA (EQ), scratch filters, rotary fader, headphone amp, main and aux output amps, and groove location.

The -C model was also 'full facilities' intended for Television Studios, with stereo and mono switching, rotary fader, RSA, scratch filters, line amp, bussing mixer, and groove location. (The bussing mixer allowed multiple replay sources to be linked together to produce a single combined output which could then be passed to the main mixing console.)

And finally, the -D model was a mono reproducer with only a single channel of electronics. It included the rotary fader, RSA, scratch filters, headphone amp, and main and aux output amps.

And... if you're interested in the pickup arm -- the MP1/18 -- that's described here: http://www.bbceng.info/EDI%20Sheets/10381.pdf

It was designed specifically for the SP10 Mark 2 turntable... and an optional pickup raise/lower mechanism for it was coded the MP1/19.

The aluminium tube arm has an effective length of 248mm, an overhang of 15.4mm, a resonant frequency (with standard cartridge) of 14Hz, and a tracking error of +3 to -1 degrees. The blurb gives the stylus pressure range as being from 1.5 to 6.5 grams.

I've not yet been able to find any schematics for the electronics, although I have confirmed that the pickup amplifier is a type AM18/17, and the RSA module is a type AM22/14.
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Re: question on the BBC turntables : opinions !

Postby Arpangel » Wed Nov 18, 2020 4:08 pm

techman25 wrote:As a TO and SM (now retired), I used this gram set up many times over the years. The turntable is a Technics SP10 modified to remove the start stop button. All the control was done from the front panel and the gram could fader start from the rotary fader. Usually this model was in dubbing suites and recording channels and a huge double version was used in GP studios for live work. The BBC suspension on these units was terrible, the whole top wobbled about and the SM would be very lucky not to jog the arm when working alongside the deck.

The Shure SC35 cartridge was common in the 80s, being also used by the pop networks in the EMT 950. This was later changed to Ortofon OM10s and the “concorde” equivalent in the EMTs but I don’t think this ever made it to the SP10 incarnations. The SC35 tracked at 5 grams and every effects record in the library had a distinctive loud burst of crackles in the lead in where they had been backtracked multiple times and the vinyl had been gouged out!

I’m not sure what the arm is, I’ve seen these with an SME arm but this looks like it could be a Technics one.

The other thing to note is that the amp and logic cards sit in a eurorack in the front of the unit behind a 1970s trendy smoked panel.

I think the arm is a Technics EPA100, or similar.
The EMT turntables are very sought after today, I think they took inspiration from the Thorens TD125.
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Re: question on the BBC turntables & EMT Turntables

Postby CeruttiA » Wed Nov 18, 2020 6:32 pm

Thank you to all,

if anyone has an EMT turntable for sale in good condition , I would be very interested.

thank you very much indeed.

Kind Regards

Alexander
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Re: question on the BBC turntables : opinions !

Postby CeruttiA » Wed Nov 18, 2020 7:02 pm

Image


This is the one I have just purchased, though the opinion of Arpangel makes me cancel my order :

"The BBC suspension on these units was terrible, the whole top wobbled about and the SM would be very lucky not to jog the arm when working alongside the deck. "

IS THE SUSPENSION REALLY SO BAD ? I payed 2000 ukp for it ... :-(
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Re: question on the BBC turntables : opinions !

Postby CeruttiA » Wed Nov 18, 2020 7:04 pm

Image
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Re: question on the BBC turntables : opinions !

Postby MOF » Wed Nov 18, 2020 7:35 pm

£2,000!!! I’d want to knock a 0 off that. Admittedly I think all that vinyl scene is more for collectors, not for absolute quality, but I see that these are collectible.
If that’s why you want it then fine, but if it’s about transferring records to digital at the best quality you’d be better off spending your money on the best current models.
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Re: question on the BBC turntables : opinions !

Postby Hugh Robjohns » Wed Nov 18, 2020 9:23 pm

I doubt you can cancel your order if it was from the auction... But no, the suspension wasn't that bad -- and for domestic use it won't be a problem at all.

The going rate for a standard Technics SP10 mk2 on the s/h market seems to be about £1500, so for the BBC heritage, cabinetry, and built-in preamp etc you're paying a £500 premium... which doesn't sound all that desperate.

You'll have fun wiring into the Hypertac connectors, though... ;)
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Re: question on the BBC turntables : opinions !

Postby CeruttiA » Wed Nov 18, 2020 9:24 pm

Hugh Robjohns wrote::thumbup: :D Good Info.

I found this BBC report on the early RP2/6 just to give some idea of the typical nature of internal gubbins and construction!

I also found a BBC Engineering Design Information sheet which describes the new RP2/10:

BBC EDI wrote: New Design
RP2/10 Disk Reproducer for new installations and to supercede obsoloete equipm,ent as appropriate. Table top cabinet;floor standing adaptation using separate plinth. Single player 33/45/78 stereo and mono. Turntable, pickup arm and associated controls as RP2/9. Uses present standard Shure SC-35 cartridge; LP or 78 stylus assemblies.

Modular organisation for installation in bespoke desks and to permit choice of facilities with electronics to match.

Replaces RP2/6. Two units on plinths may replace RP 2/1 types. EDI No.10354 Refers.

For further information please contact W T Shelton, Room 302, Western House PABX LBH 3867.

This EDI is available here: http://www.bbceng.info/EDI%20Sheets/10358.pdf and gives brief descriptions of the earlier RP types.

And, much more importantly, the EDI 10354 mentioned above details the RP2/10 specifications and its optional facilities here: http://www.bbceng.info/EDI%20Sheets/10354.pdf

In particular, it mentions the outputs are via Hypertac connections...

I've also discovered there were at least four variants identified as the basic RP2/10, and then RP2/10B, C and D.

The basic RP2/10 was a 'minimum facilities' version for Continuity suits, but included the scratch filters, switched output attenuator, and groove location.

The -B version was a 'Full facilities' model for Radio and External Broadcasting with stereo/mono switching, RSA (EQ), scratch filters, rotary fader, headphone amp, main and aux output amps, and groove location.

The -C model was also 'full facilities' intended for Television Studios, with stereo and mono switching, rotary fader, RSA, scratch filters, line amp, bussing mixer, and groove location. (The bussing mixer allowed multiple replay sources to be linked together to produce a single combined output which could then be passed to the main mixing console.)

And finally, the -D model was a mono reproducer with only a single channel of electronics. It included the rotary fader, RSA, scratch filters, headphone amp, and main and aux output amps.

And... if you're interested in the pickup arm -- the MP1/18 -- that's described here: http://www.bbceng.info/EDI%20Sheets/10381.pdf

It was designed specifically for the SP10 Mark 2 turntable... and an optional pickup raise/lower mechanism for it was coded the MP1/19.

The aluminium tube arm has an effective length of 248mm, an overhang of 15.4mm, a resonant frequency (with standard cartridge) of 14Hz, and a tracking error of +3 to -1 degrees. The blurb gives the stylus pressure range as being from 1.5 to 6.5 grams.

I've not yet been able to find any schematics for the electronics, although I have confirmed that the pickup amplifier is a type AM18/17, and the RSA module is a type AM22/14.


Thank you very much Hugh : you mention the Hypertac connections : Will I still be able to connect them to the Rogers 5/8 ???????
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Re: question on the BBC turntables : opinions !

Postby Hugh Robjohns » Wed Nov 18, 2020 9:29 pm

Technically, yes, if you know what you're doing and can reverse-engineer the internal wiring or modify the unit for different output connectors.

But I don't think it's going to be plug'n'play simple.

And getting hold of the schematics might prove tricky. A lot of old BBC equipment info is available online now -- as I've already shown -- but I couldn't track down the RP2/10 schematics details, or even the individual sub-element schematics, anywhere.
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Re: question on the BBC turntables : opinions !

Postby CeruttiA » Wed Nov 18, 2020 9:43 pm

Dear Hugh - or anyone else : are you sure that it does not have the normal 6 pin connectors for the output?

In which case I can not really use it without spending more money on an engineer to modify it !

If you have an idea how to change it I will be madly grateful.
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Re: question on the BBC turntables : opinions !

Postby CeruttiA » Wed Nov 18, 2020 10:21 pm

Actually , in the Specs it says for 'Output' : "balanced, floating, min load impedance 600 Ohms,

so , it does, perhaps , have the normal , balanced connectors ?
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Re: question on the BBC turntables : opinions !

Postby Hugh Robjohns » Wed Nov 18, 2020 10:38 pm

CeruttiA wrote:Dear Hugh - or anyone else : are you sure that it does not have the normal 6 pin connectors for the output?

6-pin connectors? No idea what you're referring to.

This appears to be a standard BBC studio-spec 'disc reproducer' and the normal connection format for devices like this -- needing connections for main and aux audio, and remote control -- was always via large Hypertac multi-pin connectors.

It's possible that this particular unit was modified in someway, perhaps to have outputs on (for you) more convenient connectors (like XLRs or PO316s)... But I think that unlikely.

If you have an idea how to change it I will be madly grateful.

It shouldn't be beyond the capabilities of an experienced technician to figure out the wiring and identify the balanced output connections, and then either wire up a Hypertac with suitable output leads, or fit alternative connectors to the cabinet.

But I suspect he/she will be working blind unless you get very lucky in finding the schematics.
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Re: question on the BBC turntables : opinions !

Postby Hugh Robjohns » Wed Nov 18, 2020 10:41 pm

CeruttiA wrote:Actually , in the Specs it says for 'Output' : "balanced, floating, min load impedance 600 Ohms,

so , it does, perhaps , have the normal , balanced connectors ?

Perhaps... But the standard Hypertac connector would also carry balanced, floating outputs expecting a minimum load impedance of 600 Ohms....

Are there no photos of the rear connection panel.
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Re: question on the BBC turntables : opinions !

Postby Arpangel » Thu Nov 19, 2020 9:12 am

Don’t panic, I would just look inside, and see where the wires go straight from the arm, tap off those, or reroute them to a pair of phono plugs and drill them into the rear of the case as a "domestic" output, just like a "normal" turntable. That has to be possible if you don’t want to use the extra bells and whistles.
Or just figure out what the signal wires are on the Hypertac connector and take a balanced output from there, whatever, it’s all definitely possible. Plus there’s loads of phono preamps about that offer balanced outputs too, if that’s what’s needed.
These are definitely a bit "boingy" in the spring department, but as Hugh says, not a problem in your living room.
You mention the LS5/8, but what amplifier are you using?
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Re: question on the BBC turntables : opinions !

Postby CeruttiA » Thu Nov 19, 2020 10:30 am

Arpangel wrote:Don’t panic, I would just look inside, and see where the wires go straight from the arm, tap off those, or reroute them to a pair of phono plugs and drill them into the rear of the case as a "domestic" output, just like a "normal" turntable. That has to be possible if you don’t want to use the extra bells and whistles.
Or just figure out what the signal wires are on the Hypertac connector and take a balanced output from there, whatever, it’s all definitely possible. Plus there’s loads of phono preamps about that offer balanced outputs too, if that’s what’s needed.
These are definitely a bit "boingy" in the spring department, but as Hugh says, not a problem in your living room.
You mention the LS5/8, but what amplifier are you using?

Hello and thanks for the reassurance (which one needs at 2.200 UKP ! ) . As you might know the rogers Ls 5/8 come with the Quads 405 (bi amplified) , this is the standard BBC modification.
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