Decca Stereo Radiogram SRG 650. Some contrarian thoughts

[David Man]

Hello everyone. This is my first post and my first project of this type (I am a vintage HI-Fi enthusiast really but love anything from this era), though some of you may have seen my posts on the FB site and have already offered help and support so thank you for that. The story is that I was generously given this SRG650 which was complete and well used condition, but not working. I have determined that it is very repairable, after stripping down and relubricating the deck (a UA15 or 16 I think) it is now working well) and the receiver/amp chassis is complete and in good condition, but I have yet to appraise it further, I have been concentrating on the cabinet which is now sympathetically restored.

So I have some questions and dilemmas and I would appreciate your thoughts. My aim is to keep this piece and use it as much as possible. Is it considered bad form to make small but significant improvements in order to make it a useable piece as well as just an interesting artifact? I am thinking of replacing the deck with something still vintage but slightly later which won't destroy my records, and perhaps improving the original speaker drivers with something more capable of making the most of that beautiful valve amp. I believe the higher end models did have two way speaker systems at that time.

I welcome your thoughts and any recommendations of what I might do to achieve my goal of a useable piece without being accused of moving over to the dark side! Or should I keep it stock and a vintage curiosity that doesn't get used, which seems such a shame. Thank you in advance for your musings.

[Station X]

At the end of the day it's your radiogram and you can do whatever you like with it.

[Edward Huggins]

I fear the OP may find that there is a bit more to this than he thinks. Upgrading the turntable unit will present problems if he decides to use a moving magnet cartridge for which the amplifiers will need a pre-amp. Upgrading the 10" X 6" speakers will not be easy as no drivers are made in that size today. The chassis is not mains isolated so there will be safety issues......Why make this classic Stereogram something that it can never be? Restore it to its original state and you will have a fine sounding Radiogram..

[paulsherwin]

As Graham says, it's yours to modify as you wish. Some people will approve and some disapprove. 60s stereograms aren't greatly sought after.

Although a relatively high quality unit, this is still a stereogram rather than a piece of HiFi equipment, and there's little you can do to turn it into one. You could fit a later higher quality deck like an SP25, but you'd still need to use a ceramic cart unless you wanted to fit an additional RIAA preamp. The speakers are also likely be very modest.

The most sensible modification would probably be to fit a cheap Bluetooth module which would allow you to stream modern material without hacking about too much. You could easily derive a power supply from the 6.3V heater line.

[Audio1950]

Originally Posted by Edward Huggins

Why make this classic Stereogram something that it can never be? Restore it to its original state and you will have a fine sounding Radiogram..

My thoughts exactly! BSR decks will not ruin your records, if they did, there would be far fewer vintage records around today, as a good percentage of them would have been played on similar changers. Apart from that, you would have to hack the present motor board about to suit the replacement, and the radiogram will never be original again.

Barry

[paulsherwin]

Does this radiogram have an input for a tape recorder? If so, it will be a simple matter to hook up a CD player or a high quality external record deck with a built in preamp - in fact, any line level source should work.

[Michael Maurice]

I know this stereogram well, There is no tape button nor tape input.

There are a lot of parts which need replacing in the radio section which is quite hard to do.

I was trying to obtain this radiogram but for whatever reason you beat me to it.

I was under the impression that you obtained it from its original owner to fully restore it to its original and not to start fitting newer turntables and/or bluetooth.

[RojDW48]

It's a good SRG. No great benefit to be had from replacing the old BSR - and 'upgrading' to an MM cartridge is the road to nowhere (unless you are an expert) plenty of good and appropriate ceramic carts to be had. One mod I think is worth doing (as I have) is the institution of a switched socket in the gram line so you can plug in a CD player or cassette player. Chances are it will match well enough - if not it's not much wasted time.

[Radio Wrangler]

With pairs of ECL82s in push-pull, the power available is rather modest. Modern loudspeaker drivers have a number of advantages, though at the cost of significant inefficiency. Attempts at upgrades in this area in period equipment have not proved wildly successful, as much from cabinet bass limitations as quieter results. The distance round through the back to the front creates an interference wave controlling low frequency rolloff irrespective of the driver. Deeper bass needs an infinite baffle , or a transmission line, or a tuned port.

If better sound quality had been my aim, I wouldn't have started with a stereogram. There are better starting points for no more money if you look around and can see past unfashionability of some brands.

David

[David Man]

Thanks for all your input, lots to think about there. In response:

It has no tape input.

Any modification would be reversible, I would not hurt it in any way.

The original owner wanted it to be restored, loved and used; I am trying to maximise that opportunity and I have discussed my thoughts with him.

I am thinking of feeding the gram line through a selector switch which will give me options yet to be thought through.

I have decided to keep the turntable, it is an essential part of the character. So what cartridge would you recommend (preferably with a low tracking weight)?

[Radio Wrangler]

You'll find that arm unsuitable for any cartridge that can work with low tracking weights. Too much friction, poor control of tracking weight. You're pretty much stuck with piezo-ceramic types with fairly low complince.

David

[Michael Maurice]

Originally Posted by RojDW48

One mod I think is worth doing (as I have) is the institution of a switched socket in the gram line so you can plug in a CD player or cassette player. Chances are it will match well enough - if not it's not much wasted time.

This is a live chassis, any mod like that would be dangerous.

[PaulR]

I think this has FM in which case you could get a cheap FM transmitter module and "broadcast" your CD player or whatever to it thereby leaving it unmodified

[Nickthedentist]

That's what I would do.

Or add a Bluetooth receiver, with live-chassis precautions.

[paulsherwin]

Bear in mind that the VHF tuner won't have a stereo decoder though, so anything sent that way will be mono.

[David Man]

Originally Posted by Station X

At the end of the day it's your radiogram and you can do whatever you like with it.

I appreciate that Station X, and it is such a lovely thing, better in the flesh than the pics can show. I want to have it sound as good as it looks, if that's possible, but I appreciate I am only the custodian, it should have a longer life than I and I want to preserve it too.

[David Man]

Originally Posted by Edward Huggins

I fear the OP may find that there is a bit more to this than he thinks. Upgrading the turntable unit will present problems if he decides to use a moving magnet cartridge for which the amplifiers will need a pre-amp. Upgrading the 10" X 6" speakers will not be easy as no drivers are made in that size today. The chassis is not mains isolated so there will be safety issues......Why make this classic Stereogram something that it can never be? Restore it to its original state and you will have a fine sounding Radiogram..

I'm sure you are right Edward, I'm not entering into this lightly. I am afraid I want to have my cake and eat it. I think you are right, but I would like to at least be able to play other sources through it, preferably in stereo.

[David Man]

Originally Posted by paulsherwin

As Graham says, it's yours to modify as you wish. Some people will approve and some disapprove. 60s stereograms aren't greatly sought after.

Although a relatively high quality unit, this is still a stereogram rather than a piece of HiFi equipment, and there's little you can do to turn it into one. You could fit a later higher quality deck like an SP25, but you'd still need to use a ceramic cart unless you wanted to fit an additional RIAA preamp. The speakers are also likely be very modest.

The most sensible modification would probably be to fit a cheap Bluetooth module which would allow you to stream modern material without hacking about too much. You could easily derive a power supply from the 6.3V heater line.

Thanks for your comments Paul, I understand the limitations, I appreciate it is not a hifi unit. Having said that, I would at least like to understand what that amplifier is capable of. I have tried looking up the specification, Freq response, S/N ratio etc, but havent found anything yet, does such info exist?

[David Man]

Originally Posted by Audio1950

My thoughts exactly! BSR decks will not ruin your records, if they did, there would be far fewer vintage records around today, as a good percentage of them would have been played on similar changers. Apart from that, you would have to hack the present motor board about to suit the replacement, and the radiogram will never be original again.

Barry

Thank you Barry, perhaps I was a little too harsh there! But if I am a novice at this, I am very well versed in the world of record reproduction and I wouldn't normally let my precious collection anywhere near a tracking force over 3 grams. But you are right... I must alter my thinking and make the most of what can be done. I will keep the deck, and invest is some records for it. What cartridge would you and others recommend?

[David Man]

Originally Posted by paulsherwin

Does this radiogram have an input for a tape recorder? If so, it will be a simple matter to hook up a CD player or a high quality external record deck with a built in preamp - in fact, any line level source should work.

Paul, this is at the very heart of what I would wish. Is it possible, and safe, do do so without a tape input. What difference in level are there between the gram input and a tape input?