Transmission Electronics, Pre IMF Transmission Line or not?

[Happyhamster]

ANY info would be great:
What i have sourced: They were designed by John Wright and built in electrical shop (Transmission Electronics) at 495/9 Oxford Road Reading Berks. The company was then called Transmission Electronics Ltd, and the products were badged IMF (Note this model in photos does not carry the IMF badge) Eventually the joint venture folded as the shop owner decided it wasn’t his “thing” anymore, and the IMF side went off I think around mid 1973 to High Wycombe and founded IMF Electronics Ltd. The company fully became IMF.

I

can't find much info on this model.
What i do know is their made by Transmission Electronics Ltd. which later became IMF Electronics.
1×Woofer Kef B139, (1973 sticker)
1×Passive Kef
1×KEF Tweeter
1×Celestion Mid
They are very well made.
Sound fantastic.

 

[planet10]

Thanx for this. Never seen it a kool but of history.

Certainly isn't a TL, but a BR with a PR.

Could maybe be a missing link between Radford and IMF.

dave

 

[Happyhamster]

The Game is to find out what you already know.

 

[dharmon]

happyhamster, are these your speakers? I saw somebody selling a pair that look the same, or very similar, so I’m wondering how do you find them? I’ve never seen an IMF speaker before that has a passive bass radiator like these. Would you say they have the same sort of quality of bass that the the IMF transmission lines speakers have? What about that Celestion mid range driver? All of the IMF speakers I’ve seen use Kef mid drivers, or their own version of it on the later models, so how do you find the mid range?

Any detail you can provide would be of help. Thanks.

 

[planet10]

Would you say they have the same sort of quality of bass that the the IMF transmission lines speakers have? What about that Celestion mid range driver?

Haven’t heard those but the smaller IMFs with PRs did not have as good a bottom as the big TLs.

dave

 

[dharmon]

Do you mean the ALS30 and ALS40, Dave? They both have two bass drivers in each cab.

 

[planet10]

One of the first things i did when we got new speakers in was to pll the bass driver and look inside. That second bass driver is a PR AFAIR. I don’t recall ever seeing an ALS30.

dave

 

[dharmon]

This must be the ALS40 in the picture, with a pair of 8” drivers for the bass. The ALS30 came out after the ALS40 II, and had a pair of 6.5” drivers. The mid and tweeter were the same in both models. The 30 was smaller and lighter than the 40.

The foam surround on the mid unit often cracks, so that the cabinet is no longer sealed. Your mids look to be In good shape, from what I can see in the picture.

 

[planet10]

foam surround on the mid unit often cracks

Peerless K040. Finding one with intact surrounds is rare.

dave

 

[dharmon]

Yes, true. That‘s the only worry about these old models. Falcon has the replacement foams, I believe.

I was hoping to get happyhamster‘s opinion on the sound quality of the speakers he bought. Well, I couldn’t help myself. I‘ve gone and bought a pair of the same 10 minutes ago on the famous auction site. I’m collecting them next week. It’s a bit of a trek up north, but I’m hoping it’ll be worth it.

 

[Happyhamster]

happyhamster, are these your speakers? I saw somebody selling a pair that look the same, or very similar, so I’m wondering how do you find them? I’ve never seen an IMF speaker before that has a passive bass radiator like these. Would you say they have the same sort of quality of bass that the the IMF transmission lines speakers have? What about that Celestion mid range driver? All of the IMF speakers I’ve seen use Kef mid drivers, or their own version of it on the later models, so how do you find the mid range?

Any detail you can provide would be of help. Thanks.

Hi dharmon, yes these mine. Have been using them for a good while now. These are fantastic sounding speakers I can't fault them I play all types of music thru them. Orgasms to my ears, surprise me they are so precise definite. I am unfamiliar with the IMF transmission lines speakers. The bass is just where I like it, with some music various if I need more, I add some with a variable loudness from amp. Defiantly keepers. If you find a pair grab them, you will be Chaffed.

 

[Happyhamster]

I was blown away when someone had come across another Pair.

 

[dharmon]

Thanks for you assessment of these speakers, happyhamster. Your assessment of them is like a good MOT with no advisories. The ones in the pictures are what I bought yesterday, and will pick up next week. Looking at the serial numbers of yours and this pair, I would think they were made in the same year - 1973, which I understand would have been the last products before they moved to High Wycombe and became IMF.

I may change the capacitors on the crossovers, as those in the cabinets will be 50 years old now. The inductors are perhaps best left well alone. I can’t see any resistors on the crossover board you have provided a picture of, and it’s a mystery as to what is inside the buff coloured plastic boxes on the board. Resistors, perhaps? Have you had a look inside to see what is in there. And are your crossovers the 1973 originals?

I like the sound a variable loudness control on your amplifier. Amps used to come with a loudness control, which was often a -20dB attenuator with a bass and treble boost. What amp are you using with yours? I would like to find an amp with one.

David

 

[Happyhamster]

Congrats on the purchase keep me posted. I have no idea if the crossovers were upgraded, will be interesting to see once u get yours if different. I have them hooked to a Kenwood pre C1 & Basic M2 power. These speakers would rejoice and shine even more if hooked to a nice valve amp I have not tried yet.