Modern speakers to improve sound in tube radios

[david winter]

Originally Posted by maxhifi

Sorry for the slight off topic but is this something commercially available?

I posted about my FM module a few days ago.
Until it's approved in the Parts & Set section, I'm giving the link in PM.

[MurphyNut]

I made an interesting discovery recently, I bought a little cheap and cheerful Bluetooth receiver and connected the output directly to the speaker of a early 1930's set bypassing the speakers transformer.
The device was able to drive the unit and it actually sounds surprisingly good as long as you don't expect it to go very loud.
Please note, don't have the radio powered up when doing this and disconnect the leads when you want to use the radio under it's own steam.

[FStephenMasek]

The original speaker in this radio was bad, so I used a modern car radio 3-way speaker. Although the speaker is driven by a single '45, it sounds nice.

[Uncle Bulgaria]

There are lots of sensitive loudspeakers around. I got a couple from Fostex, who were also very helpful with designing me a small bit-bigger-than-bookshelf ported cabinet. They were for a 300B and may have been 95dB/W.

[FStephenMasek]

I have that same model Renegade 3-way speaker in my custom-designed radio with push-pull 6L6GC output tubes, and it also works well in that application, far more power than a single '45 is able to output. https://www.amazon.com/Renegade-RX83.../dp/B0045V5WLC

[simpsons]

Ah, Mr winter. So it's FM radio you're after on an AM radio's audio circuits together with a speaker to match.

This is a wonderful exercise that will hopefully generate some feedback. No pun intended.

There are threads on a "must-read" DAC 90a modifications sound improvement, improving Bush Audio and missing tone correction which will illustrate how just using existing circuits may well disappoint.

I'm not into car speakers which are required to operate in extreme heat and cold and from a design perspective to work in a given enclosed space. Sold to enhance OEM's but not always with a frequency response chart to see if suitable for door mounted off-axis reproduction or boot mounted for that extra boom and tizz.

What I have done is use my home speakers ( Tannoy Eaton) as a reference when listening to both Grundig 3028 and Philips Saturn 563 placing them on an armchair. The Saturn is in a league of its own with its transformerless push-pull output, high impedance speakers, side-mounted mid-range speakers fitted with whizzers shaped to throw high notes forward whilst the Grundig is not bad at all - both with flat tone correction. Phew, now take a breath!

Both designs are well-engineered for "faithful" sound reproduction and should this be your objective, I hope reading the above threads will give you food for thought.

Chris

[david winter]

Thanks to all of you for your advises and experience.
It took me a dew days to get back to you as I got sick (and didn't fully recover yet) and had to deal with the FM module which generated some interest. As time was limited, I chose to wait a little bit before getting back here.

Radios which have an 8" speaker almost never disappointed me except a few 1930s models. As Chris says, I too had good German types (Telefunken, Grundig, Saba, Blaupunkt) and those gave excellent results.

The speakers that I want to replace to improve the sound are those used in smaller radios, with a diameter of around 4-5 inches. The FM mod works ok on them, but the sound is far from what I hear with 8" speakers.

[simpsons]

David, I've done this myself with a Roberts RD11 which used 2 off 78mm or 3" speakers which have a stiff foam suspension. I replaced them with a Chinese made full-range speaker with a rubber suspension. The difference was marked BUT, as mentioned earlier, the voice coil bottomed on high bass notes.

Sony and Pure, for example, do use good speakers but it is the placement of these radios which makes a difference. I find they need a soundboard to help get the sound acceptable, My bathroom floor is excellent whilst the window cill is naff!

One issue is the magnet and the space available in the radio and how the speaker is mounted. In a wooden cabinet, not too much of a problem but a plastic box usually requires mounting clips and its touch and go if the baffle is really up to the job.

There are good speakers available in the UK from CPC, eBay and the like BUT, you will now need to pay import duty on anything purchased from the UK* and shipped to the EU and, of course, you no longer have the consumer protection of EU Law. Last but not least, customs and border checks have increased shipping costs making UK purchases more expensive than before. *This doesn't apply to goods purchased from Northern Ireland as they remain in the EU single market.

There are good French and German manufacturers and suppliers which, from my experience of ITT Europe when I worked for them, will meet your needs and, I am sure, once the exact radios that you are seeking to improve are known, these can be checked out.

Chris