Mystery radio - Charles Amplifiers

[Frank.Keane]

Hi - I'm new here and have joined because no amount of searching the internet has thrown any light on a radio I was looking at the other day. I'm hoping someone on this forum will know something about the 'Charles Amplifiers' radio in the pics I have attached. So far I have no information at all.

[paulsherwin]

It looks a bit repro/fake to me - a touch of the Steepletones about it.

[Cobaltblue]

Well the tuning scale is probably real.

So I suspect the whole thing is, a few more pictures of the Chassis would help

https://www.gracesguide.co.uk/Charles_Amplifiers

Cheers

Mike T

[Frank.Keane]

I know what you mean Paul but I don't think so as it was very heavy - almost of military strength. Thanks Cobaltblue that's fantastic to know the company actually did exist - and so quick too.

[Nuvistor]

Advert for their amplifiers, WW 1948.

[Graham G3ZVT]

The R.A tuning unit is superficially, similar, and apparently available in superhet and TRF versions, so I would expect a different scale layout for each. Perhaps the industrial rack mount version was a special. A TRF option seems strange for a 1949 domestic set from a manufacturer with, shall we say, elitist leanings.

https://reader.exacteditions.com/issues/32825/page/44

[turretslug]

Hi Frank and welcome to the forum. There were a small selection of radio tuners made for professional/industrial use and various situations such as distribution around schools/institutions, Forces "morale receivers", shipboard use etc. over the years. Quite often, they were based around a good-quality domestic tuner- e.g. the BBC used Chapman S6 tuners built into a 19" panel with peripheral circuitry- and your device with its apparently domestic radio tuning scale but grey-painted panel and chromed handles would very much seem to fit into this category. For professional use, features such as an RF stage (better sensitivity and spurious rejection) and/or 2 IF stages (better selectivity and AGC performance) were often deemed desirable- is it possible to post some pictures of the topside and/or under-chassis gubbins? That would give some more clues,

Colin

[Hartley118]

Originally Posted by rambo1152

The R.A tuning unit is superficially, similar, and apparently available in superhet and TRF versions, so I would expect a different scale layout for each. Perhaps the industrial rack mount version was a special. A TRF option seems strange for a 1949 domestic set from a manufacturer with, shall we say, elitist leanings.

https://reader.exacteditions.com/issues/32825/page/44

Back in the days before FM and before steep-cut HF filters on AM transmissions, a good TRF was typically the highest quality receiver. This tuner looks to be the sort of unit intended for a quality school radio system or a source of 'Music While You Work' in a factory PA.

Martin

[crackle]

The knobs on that radio are the same pattern as used on KB radios from about 1934 to about 1938.

Mike

[John10b]

Nuvistor posted a reply, which seems to indicate it origin, yet no one seems to comment on that ? How he managed to research that info is very impressive!
Cheers
John

[Frank.Keane]

Cobaltblue's tip helped me find the following info

Charles Amplifiers Ltd.
British valve amplifiers believed to have been in production from 1946 to 1951 although this is not for certain, there were probably three models made all in all but we only have information on 2 of them; the Concerto a 12 watt amplifier that features 8 triode valves plus an AC rectifier valve, priced at 27 pounds & 10 shillings in 1948 and a smaller 5 watt push-pull amplifier with negative feedback that was called the KI, that featured 7 valves in total and was sold for 17 gns., or in kit form where it retailed for 13 gns.. Both amps had output transformers that offered taps with 15, 7 and 3 ohm impedance outputs, phono and radio inputs and bass and treble controls but in addition the Concerto had a 2 level bass boost available.

These amps are rare, and notable for a number of reasons, these are integrated amplifiers in the modern sense while at the time most amplifiers were power amplifiers since they were intended either to hook radios to a larger loudspeakers or like the products from Quad Electroacoustics et. al. were actually designed for PA systems and were commonly not shipped with output transformers but rather you got them wound to match your speakers and in the case of PA applications the transformers actually came with the speakers, not the amps. The Charles Amplifier models had an especially flexible phono input that could accommodate anything from a radio level (line level) signal from a crystal pick-up, any sort of magnetic cartridge or even a moving coil pickup, but the support for MC's is interesting since they were as rare as hens teeth at the time in the UK, being a specialist and expensive import form Denmark (Ortofon). In other words the Charles Amplifier products are probably the first UK examples of such specifically designed as home hi-fi amplifiers making the company one of the first hi-fi companies in the UK.

[Radio Wrangler]

I just googled 1e Palace Gate, Kensington.

That is an unbelievably posh address. Maybe an office, perhaps a demo and sale room. Very likely not the factory.

I'd never heard of them before, and I suppose many other people also hadn't.

David

[Nuvistor]

Originally Posted by John10b

Nuvistor posted a reply, which seems to indicate it origin, yet no one seems to comment on that ? How he managed to research that info is very impressive!

Nothing special from myself, if you have not seen this web site before, be warned it can “waste” many hours. Many magazines most with a search function.

http://www.americanradiohistory.com

A really excellent store of information.

[Sideband]

As has been suggested, I think it is a 'tuner unit' to complement one of their amplifiers. Please....lets see some photos around the back or even inside if possible. If it is just a tuner it won't have an output stage which means it has to be connected to an amplifier to hear anything

[Graham G3ZVT]

Another tip Frank, when you do a Google search on anything, it's always worth selecting the "Images" option at the top of the page.

[turretslug]

Peripheral to the thread, but the first radio I recall seeing with the Oulu 433kHz allocation marked on the dial- beyond the LW tuning range of most radios! Having a 600m (500kHz) mark on the LW scale would imply an IF outside the mainstream 450-470kHz range.

[Graham G3ZVT]

Or perhaps an IF of zero, as previously discussed.

[Paul_RK]

Originally Posted by turretslug

Having a 600m (500kHz) mark on the LW scale would imply an IF outside the mainstream 450-470kHz range.

Or maybe a part of the band accessible only in TRF mode?

Originally Posted by rambo1152

The R.A tuning unit is superficially, similar, and apparently available in superhet and TRF versions, so I would expect a different scale layout for each...

https://reader.exacteditions.com/issues/32825/page/44

My guess would be that, as when Dynatron introduced their first superhet chassis in 1937, the tuner was designed to be switchable between superhet and TRF operation. In the Dynatron instance switching to TRF happened when the broadest of a range of bandwidth settings was selected.

Paul

[Graham G3ZVT]

Now, this is getting interesting.
The wording in the advert says "High fidelity superhet or TRF performance", I must admit that I did not consider they might be talking about both on the same chassis.

Also, as Martin, Hartley118 pointed out, if it's a trade-off between fidelity (bandwidth) and "performance" (selectivity), haven't they got the marketing spiel the wrong way round?

[Paul_RK]

Originally Posted by rambo1152

Also...if it's a trade-off between fidelity (bandwidth) and "performance" (selectivity), haven't they got the marketing spiel the wrong way round?

If "High fidelity" is read as applying only to "superhet", yes indeed, but can't it as easily be read as covering operation as superhet or as TRF?

Jonathan Hill's "Audio! Audio!" lists five models of Charles amplifier from the period 1947-52, with the first to appear, the Concerto, offering output of 13 watts from two PX25s and "Designed for quality reproduction of records in the home". There's no mention of tuners, which fall outside the scope of the book.

Paul