Hi. I have been wondering about aquiring a vintage speaker for when I (one day) revive my Ericsson 4 valve receiver circa 1922.
How much should I pay, how rare are such items, or do they pop up regularly like old irons and toasters? ( I made a joke!)I know there’s one on eBay now but I’d like to know if it’s a rip off or not.
Thanks Murray

do they pop up regularly

Can't speak for QLD, but they do appear from time to time at Sydney HRSA auctions and there's usually one or two at the swap meet type days.

As to value, well, as usual, that depends on what the buyer will pay and the seller will accept. Condition also plays a big part.

I've sometimes been surprised at the prices they can obtain, but the highest prices tend to be bid by collectors of such speakers.

Will that Ericsson 4 drive a speaker?

GTC I guess that’s a good question. I’m absolutely guessing, as I cannot glean any info about this radio, beyond what is available on rm.org. Was this receiver only useable with ear phones? I cannot get a schematic anywhere, or contact an owner of similar set.
Just looking at the radio museum again- it says for earphone or amp, so does that mean a horn could be used with an amp?
Murray

Given the vintage (1920s), I expect it was designed for high impedance headphones.

Have you tried asking about it on the UK forum?

https://www.vintage-radio.net/forum/

GTC thanks for the heads up. That is one avenue I hadn’t covered. But I have just joined and submitted a post on the forum. Let’s hope this uncovers some help.
Murray

If you search you will find pics. Most of the sets of that era followed a similar plot & were transformer coupled TRF's. Superheterodynes were rare, albeit I have one to fix from that era.

Not many had an output transformer. I normally reverse engineer them if there is no circuit. Perhaps the valve line up in it and a photo might help? Otherwise it's assumptions.

Ok . I had a few replies on the uk forum. Nothing groundbreaking, but one fellow stated something along the lines of what Marcc said- to trace the circuit out and work it out. I like the reverse engineering idea. I just don’t have the knowledge to do that yet.
Murray

I like the reverse engineering idea. I just don’t have the knowledge to do that yet.

Not too hard and those early sets tended to follow, at core, a few fairly common designs, as there weren't too many designs around at the time. This would be a good exercise for you.

The worst part is normally the wire entanglement up front depending on how many coils etc.

With four valves it may be 1st RF; 2nd RF; Plate detector & OP. These will all be triodes but Tetrodes did arrive early.

The transformer couple is easy. What is needed is the numbers off of the valves. Philips had a bad habit of using the sides of the envelope or the top. One might be PM4 or 614? That sort of thing. A photo, or two, should give some of us an idea has to what they did & we work from there.

Auto focus is not your friend. If possible keep the f number high (say f8) and focus in the middle of the subject.

O.k so just to clarify.. this set is in pretty bad shape. I have already put a post about it, in "cabinet repairs" back in march this year, which you may have read. That was my first post.

Rather than me re-post the same photos, you can have a look there. Don't laugh too hard! If it wasn't so apparently rare, I would kick it to the curb!

It has sent me on a mission to learn enough to be able to fix it. I am on to my fourth radio repair, one of which is well documented in the wanted for sale section, a Kriesler 11-81. (still not going but getting close now, I hope. I'm pretty sure that set was cursed by the gods)
Murray

Any radio can be hooked up to an amplifier provided it is done the right way,
such as using an audio impedance matching transformer.
valves do like running into the correct load
so correct impedance is important
but once you know that you can simply
use a transformer to match that up to the amplifier.
Altronics in Perth has a good range of audio transformers.

Hi Murray,

I think your set will almost certainly be a regenerative detector design. It will definitely drive a horn speaker (the horn will be the plate load for the last valve). But if you want to recreate the set up for your set you will need to find a very early speaker - which might be difficult. Mid 20's and later horn speakers are fairly common and you should be able to find one at a HRSA auction for between $80 and $200. Some of the earlier UK speakers were made of 'interesting materials' and haven't survived well. Ones in good condition generally make very good money. For circuit design ideas you could look up those by John Scott-Taggart. He published 100's of designs from the late teens to the end of the 40's. A circuit for your set would be very similar or the same as his 4 valve sets of the era. If you can't find an original (likely), then one by JST will work. If you absolutely can't find one of his let me know and I'll scan what I have.

Robert