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Old 12th Sep 2020, 12:11 pm   #1
thermionic
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Default RGD amplifiers?

A friend, who is a vintage HiFi dealer, has just dropped a pair of these amplifier chassis in for me for sympathetic restoration. He thinks they are of RGD manufacture, but there is no identification on these to suggest if this is correct.

I assume if so, these would have originally been part of a radiogram chassis, with one chassis per gram unit. The valve line up is, UU7,2x PX4ís (PP3/250), HL41, SP41.

Any information would be gratefully received. They are certainly well built. The date on the electrolytics is 1946.

Cheers.

SimonT.
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Old 12th Sep 2020, 12:19 pm   #2
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Default Re: RGD amplifiers?

RGD 1046 amplifiers. Worth a lot of money. Shame about the two vintage radiograms that were smashed up to salvage them for the sake of audiophoolery, but at least you didn't do it!
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Old 12th Sep 2020, 1:04 pm   #3
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Default Re: RGD amplifiers?

I'm looking at the radio section of a 1046 here in the Bexhill office workroom Techman/Simon. The mounting board is vertical on the shelf but in the Gramophone, it would be horizontal [next to the deck]. The amp is underneath the shelf and very heavy. Two of them in the same cabinet would have been both a physical and financial strain but the post war RGD's of that quality weren't stereo.

It's a sad and happy story. I got married in August 1988 and there was a major heatwave at that time. [Unusual then-especially in Lancashire.] We set off to travel around at one point but it was so hot we stayed local in the end. We then visited an auction in Bury. I had to leave for some reason and my wife stayed to bid on this hemmed in RG at the back of the room, which I didn't expect to get. Nobody was interested and the jaded but surprised auctioneer accepted 50p. .

There was no concept of high value and asset stripping re Radiograms at that time. I was a bit surprised when she turned up with it as I had quite a few of them already [another long story]. I had no knowledge of the RGD Company [Telford?] and it was the first gram I'd seen that was so easily disassembled electrically as the various leads mostly plugged into the relevant unit, including the amplifier of course! Well I didn't actually smash it up but it WAS disassembled and eventually the cabinet went the same way although I still have all the electronics and the front panel that carried the speaker. Not really a "smash and grab" but I definitely picked the wrong one out of the group to take apart. Others have related similar sob stories. Not something I would condone or contemplate nowadays of course, for any reason!

If you put the details in search Simon, there are threads by people who have worked on the 1046.

Dave W

Last edited by dave walsh; 12th Sep 2020 at 1:21 pm.
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Old 12th Sep 2020, 6:37 pm   #4
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Default Re: RGD amplifiers?

Hi Techman & Dave.

Thanks for confirming that they are of RGD manufacture and provide a model number. Iíve searched the posts and found lots of info and a circuit diagram👍 I understand that my friend has had this pair of amps for years, but now has a (foreign) buyer. Iíll be restuffing components as required and he wants no cosmetic attention,just a gentle clean. It must work safely and well, but also look itís age.
Iím not sure if he had broken up the original cabinet and disposed of the other parts, but somehow doubt it. Heís been buying and hoarding lots of audio related items over many years.

Iíve done loads of vintage amps for him over the years, he knows his market! The upside is that I get to listen to a wide variety of amplifiers that are well beyond my pocket!
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Old 12th Sep 2020, 8:14 pm   #5
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Default Re: RGD amplifiers?

I have to confess that a number of modifications have been done to my RGD 1046 amplifier.
The output transformer is replaced with a Williamson type component.
The PX4 triodes replaced by triode connected KT66 beam tetrodes.
Other modification include Williamson balance controls for the output stage.
The change of output valves is made possible because the mains transformer has a 6.3volt heater winding. Also has a 4volt tap for PX4s.
This the later version of the 1046 having separate bass and treble tone controls which work within the negative feedback loop.

DFWB.
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Old 12th Sep 2020, 8:35 pm   #6
dave walsh
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Default Re: RGD amplifiers?

Just to make it clear [post 3* ] I wasn't saying that I had lots of RGD Radiograms at the time [I wish] just a motley collection of somewhat inferior more "modern" ones. I'd been told that the disused Cinema in Rawtenstall was being emptied for conversion into a shopping arcade and some RG's had been left there. I couldn't turn up at the time indicated but the owners left them at the Bus Station [next door] in the care of the staff. I turned up in my Vauxhall Estate to find them piled up waiting in a corner near the office [the Radiograms that is!] In all honesty, could you imagine it happening now? That's the North for you. Notice I didn't even say Lancashire Re the 1046, my wife says the auctioneer said [hopefully] how about a pound? Silence, so she said"50p". Years later I was in the same position in Bexhill on a rainy day, really ill with the flu. The auctioneer there was equally dismissive of "this radio thing". I had previously noticed it was a 1948 Mirror Lid TV and quickly shut the top. He said "Is there anybody interested? I said "ten quid" Sold! [My wife would have gone for 50p again but I just couldn't risk it].

Let us know how you get on please Simon. Photo's would be great!

Dave

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Old 13th Sep 2020, 2:06 am   #7
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Default Re: RGD amplifiers?

They look like Woden transformers.
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Old 13th Sep 2020, 5:06 am   #8
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Default Re: RGD amplifiers?

As Techman says, Definitely RGD1046 amplifiers.
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Old 13th Sep 2020, 1:50 pm   #9
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Default Re: RGD amplifiers?

RGD moved during ww2 to a location in my home town of Bridgnorth the Pale Meadow Works. Remaining there till i think about 1953 when the Automaic telephone and electric co AT&E moved on site, so fairly sure amps may have been built along with radiograms etc in Bridgnorth
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Old 13th Sep 2020, 5:08 pm   #10
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Default Re: RGD amplifiers?

According to the RGD service manual there was a console version, so it may not have been a pair of radiograms that were sacrificed.
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Old 13th Sep 2020, 5:21 pm   #11
dave walsh
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Default Re: RGD amplifiers?

I seem to remember one of Chas Millers tales in The Radiophile, Bill, where he recounted picking up [from a barn] an RGD set up. It consisted of four pieces [cubes?]. It didn't seem to fit with anything I knew about the companies RG products [I did know something eventually] so maybe there was some sort of "one off" stereo unit in existence after all He also wrote about going to see the site of the former Radiogram Development Company which, by then, was a housing estate Maybe that was the pre-war location? Chas would have known it well I'm guessing!

Dave W

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Old 13th Sep 2020, 6:18 pm   #12
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Default Re: RGD amplifiers?

Ooh, the RGD1046 amplifier…. I remember buying one of those from a friend's Dad back in 1974 for 50p…

When I picked-up the RGD from my friend's Dad, he showed me the 50W amplifier he’d made from the Mullard data book using 2N3055’s …. He exclaimed “you don’t want to be playing with old valve amps, you should be using transistors” sadly, I cannot remember my reply, but I figure I would have just smiled politely.

Anyway, sadly long, long, long gone,

Terry
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Old 13th Sep 2020, 9:40 pm   #13
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Default Re: RGD amplifiers?

About 30 years ago I bought a 1046 from an auction in Bridgenorth, the auctioneer laboured the point that it was locally made, but nobody was interested so I bought t for the first bid of £5. The cabinet is poor, I have been hoping I might find a good one cheaply without its power amp, but I expect they go straight to the tip once the amp has been removed.
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Old 13th Sep 2020, 10:06 pm   #14
dave walsh
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Default Re: RGD amplifiers?

At one point Chas said that he might have an empty 1046 cabinet, after hearing my story but I didn't follow that up. Maybe I'd thought that it wouldn't be really original? It was also a long time ago electrogram, so I doubt that the empty box he had was a simple asset strip back then. They probably just did something else with the contents like the WW2 Surplus or Terry's friends Dad [50p]. It's very different now of course but does reminds me of the Dutch black tulip craze.

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Old 13th Sep 2020, 10:48 pm   #15
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Default Re: RGD amplifiers?

It's only in the last few years, with the appearance of the amps on eBay, that it has occured to me that there might be cabinets out there. I'm afraid I am guilty of dismantling a number of radiograms, just because there was nowhere to put them, but the 1046 was always to be a keeper. if something was available very cheaply or for nothing I couldn't leave it. One I particularly regret breaking was a just prewar Barker with all b7 valves and push pull pentodes.
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Old 14th Sep 2020, 3:53 pm   #16
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Default Re: RGD amplifiers?

Chas Millers comments abouit seeing a housing estate would fit the RGD site at Bridgnorth. Tatung beiing the last occupier of the site after Decca sold it to a developer and yes now a housing estate.
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Old 14th Sep 2020, 4:19 pm   #17
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Default Re: RGD amplifiers?

Quote:
Originally Posted by Techman View Post
RGD 1046 amplifiers. Worth a lot of money ...
They'd be worth a lot even for some of the parts. But does the choice of output impedances (it looks like 15ohms or 2ohms) not put people off ?

Cheers,

GJ
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Old 14th Sep 2020, 5:20 pm   #18
dave walsh
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Default Re: RGD amplifiers?

Good question [although I still have the original 15 ohm unit]. Wouldn't two 8 ohm speakers in series work? I always understood that a couple of them [in phase] would function without any discernible loss of output and valve gear is usually more tolerant.

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Old 14th Sep 2020, 5:54 pm   #19
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Default Re: RGD amplifiers?

If we're thinking the target market is audio people then I suspect that they're not the sorts who would heap speakers up to make 15ohms . That said there are a few classic speakers which are still much loved by some in the audio community (Quad ESL, various Tannoys, Lowthers etc) and 15ohms would be correct for them.

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Old 14th Sep 2020, 7:44 pm   #20
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Default Re: RGD amplifiers?

The manual refers to 8 ohm, but doesn't identify the taps.
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