Need help identifying a pair of Vintage Speakers?

[ajgriff]

This recent thread might be of interest:

https://www.vintage-radio.net/forum/...d.php?t=158404

Alan

[Niall76]

Originally Posted by ajgriff

This recent thread might be of interest:

https://www.vintage-radio.net/forum/...d.php?t=158404

Alan

What an excellent thread thanks Alan, great to know the history behind these!

[Niall76]

Originally Posted by GrimJosef

Speakers and record cartridges are the most varied things in hi-fi systems - what Peter Walker said about all amplifiers sounding the same (he actually said something more careful than that, but you get the point) has been true for quite a long time.

We do have to be careful when it comes to listening to speakers. It's quite easy to make ones which sound 'amazing' to begin with but which are actually altering the music and which can become tiring after a while. There are also limited, dull speakers out there. But if a speaker 'just' sounds neutral then that may not be a bad thing. It may be accurately reproducing the music when we have got used to something more brash and coloured. You might want to give the new old speakers a bit more time and see if they grow on you.

Cheers,

GJ

Actually I hooked them up again and gave them another go, they are fantastic, but best enjoyed loud!

[Radio Wrangler]

They are exactly the sort of speaker that people sell because they're a bit too big, then spend the rest of their lives regretting it.

That sentiment has been expressed a few times in various threads on here, including about LNB Paralabs.

My transmission line jobs are definitely big, but they're part of me and they're staying.

So before you sell, ask yourself if you are really really sure.

Good speakers are unimpressive, they just vanish and only the music remains.

David

[LNBAudio]

My first thought was LNB, but the height doesn't coincide with the info for the models that I've got to hand Photo album
"The hockey stick" moulding that the false front sits in, the feet, white back and terminals are all pretty typical though. I'll speak to dad at the weekend and measure some speakers if I get the chance.

[Niall76]

Originally Posted by LNBAudio

My first thought was LNB, but the height doesn't coincide with the info for the models that I've got to hand Photo album
"The hockey stick" moulding that the false front sits in, the feet, white back and terminals are all pretty typical though. I'll speak to dad at the weekend and measure some speakers if I get the chance.

Brilliant, thanks😊

[Niall76]

But I did spot this on google, these are exactly like mine, and the have the LNB logo too?

[Niall76]

Originally Posted by Radio Wrangler

They are exactly the sort of speaker that people sell because they're a bit too big, then spend the rest of their lives regretting it.

That sentiment has been expressed a few times in various threads on here, including about LNB Paralabs.

My transmission line jobs are definitely big, but they're part of me and they're staying.

So before you sell, ask yourself if you are really really sure.

Good speakers are unimpressive, they just vanish and only the music remains.

David

Very wise words David, given me some food for thought 🤔

[Radio Wrangler]

To produce bass audio of a certain frequency of a certain level, you have to shift a certain amount of air. There are no short cuts, no joker card to play.

This implies that anything in a small cabinet will hit limitations it cannot go beyond. Anything in a larger cabinet may be able to do the required air movement but needing high internal pressure changes or large cone excursions which translate into distortion. So you wind up with larger speakers inevitably being less compromised than smaller ones.

Many small speakers have been designed to sound impressive by making their low frequency response have a prominent peak just above their low frequency roll-off. This can give appreciable clout to drum sounds but leads to what's called 'one note bass'

Most people are used to small speakers and this psycho-acoustical trick. So when they come across speakers which can do accurate bass down to lower frequencies, they are left feeling something is missing... for a while... and then they start noticing things in the music they hadn't heard before.

Having unidentifiable speakers without badges can be a hoot! Visitors with audio inclinations see them and hear them, but because they can't identify them, they don't know what they're supposed to say about them. Normally they identify a speaker, remember what an accepted pundit said in a magazine review and then trot out those phrases. No hearing or thinking required, just eyes to see the badge and a very good memory. All that time they spend poring over reviews is for memorising them. If they are ever found to come out with an opinion different to the pundit one, that's their audio cred right out the window

Have fun!

David

[rontech]

I agree wholeheartedly with the comments about neutral speakers. I had a pair of simiilar Lentek speakers back in the 1980's. Unfortunately they were too large for optimum placement in my listening room.

When pulled out 3 ft or a bit more from the side and rear walls, the stereo imaging was almost holographic|. When there was real bass in the source material, it was really "there" otherwise no false "boom"

Such a location was not practicable domestically though.

[LNBAudio]

We can't come up with anything LNB and 69cm tall (which isn't to say that it doesn't exist-the memory is going back between 35 and 55 years!)
Please check the measurements and pop the false fronts off, which might be a task in itself , and post some more photos

[GrimJosef]

Originally Posted by Radio Wrangler

To produce bass audio of a certain frequency of a certain level, you have to shift a certain amount of air. There are no short cuts, no joker card to play.

This implies that anything in a small cabinet will hit limitations it cannot go beyond. Anything in a larger cabinet may be able to do the required air movement but needing high internal pressure changes or large cone excursions which translate into distortion. So you wind up with larger speakers inevitably being less compromised than smaller ones .../

It's true that there's a three-way trade off between bass extension, speaker size and efficiency for speakers delivering a certain degree of distortion. But some significant technical progress has been made with large excursion drivers. I heard a pair of these http://murphyblaster.com/content.php?f=CAOW1.html recently which use this bass driver http://www.madisound.com/loudspeaker..._Datasheet.pdf. With 20mm p-p of total travel, 10mm of which is linear, these do shift a certain amount of air, at least down to 50Hz.

Cheers,

GJ

[Radio Wrangler]

Even with a nice, linear driver, if the driven volume becomes a significant fraction of the cabinet volume, there is non-linearity in the compression of the air as the pressure is proportional to the reciprocal of the remaining internal volume, not to the displacement of the driver.

As a yank racer once said, 'There's no substitute for cubic inches'

David

[GrimJosef]

Originally Posted by Radio Wrangler

... if the driven volume becomes a significant fraction of the cabinet volume, there is non-linearity ...

A 5 inch diaphragm (say 13cm diameter) travelling over 1cm sweeps out a volume of a little over 130cc. The raw cabinet volume is 10,600cc but there is some foam lining on the walls and the driver magnet projects back into the cabinet so, for argument's sake, let's take the free air volume as 10,000cc.

The question is whether 130 is a 'significant' fraction of 10,000. I haven't worked through the algebra, but off the top of my head it feels as though, at the limits of the motion, the contribution to the air spring's total force from the quadratic term is 130/10,000 = 1.3% the size of the contribution from the linear term. Higher order terms will be down by further factors of 130/10,000. There is, in addition, a force coming from the diaphragm's support elements - the cone's surround and any centring spider close to the voicecoil. Since the total restoring force is the sum of the support force and the air spring force the nonlinearity due to the air spring will be diluted further.

Would I be right in thinking that at the level of 1.3% the nonlinearity of the air spring won't make an audible contribution to the speaker's distortion spectrum ?

Cheers,

GJ

[Radio Wrangler]

Probably not, but when you get to some of the units with very long throw drivers in cabinets hardly bigger than the driver...

Anyway those LNBs are transmission line jobs so the pressure from both ends gets used down at the frequencies of greatest excursion and the overall volume puts them well clear of such concerns.

David

[Niall76]

Originally Posted by Radio Wrangler

To produce bass audio of a certain frequency of a certain level, you have to shift a certain amount of air. There are no short cuts, no joker card to play.

This implies that anything in a small cabinet will hit limitations it cannot go beyond. Anything in a larger cabinet may be able to do the required air movement but needing high internal pressure changes or large cone excursions which translate into distortion. So you wind up with larger speakers inevitably being less compromised than smaller ones.

Many small speakers have been designed to sound impressive by making their low frequency response have a prominent peak just above their low frequency roll-off. This can give appreciable clout to drum sounds but leads to what's called 'one note bass'

Most people are used to small speakers and this psycho-acoustical trick. So when they come across speakers which can do accurate bass down to lower frequencies, they are left feeling something is missing... for a while... and then they start noticing things in the music they hadn't heard before.

Having unidentifiable speakers without badges can be a hoot! Visitors with audio inclinations see them and hear them, but because they can't identify them, they don't know what they're supposed to say about them. Normally they identify a speaker, remember what an accepted pundit said in a magazine review and then trot out those phrases. No hearing or thinking required, just eyes to see the badge and a very good memory. All that time they spend poring over reviews is for memorising them. If they are ever found to come out with an opinion different to the pundit one, that's their audio cred right out the window

Have fun!

David

You are certainly right David on my short listens so far i definitely hear things in my albums in haven’t heard before and the bass feels less punchy but more truer if you know what I mean. If only I had a nice big room for them

[Niall76]

Originally Posted by rontech

I agree wholeheartedly with the comments about neutral speakers. I had a pair of simiilar Lentek speakers back in the 1980's. Unfortunately they were too large for optimum placement in my listening room.

When pulled out 3 ft or a bit more from the side and rear walls, the stereo imaging was almost holographic|. When there was real bass in the source material, it was really "there" otherwise no false "boom"

Such a location was not practicable domestically though.

I have the same problem lol unfortunately just do not have the room at the moment, but these would be perfect for someone lucky enough to have a listening room

[Niall76]

Originally Posted by LNBAudio

We can't come up with anything LNB and 69cm tall (which isn't to say that it doesn't exist-the memory is going back between 35 and 55 years!)
Please check the measurements and pop the false fronts off, which might be a task in itself , and post some more photos

Apologies! My measurements were wrong they measure 76.5x 28.5x 29cm and here is a couple of more pics hope this helps!

[Niall76]

Originally Posted by LNBAudio

We can't come up with anything LNB and 69cm tall (which isn't to say that it doesn't exist-the memory is going back between 35 and 55 years!)
Please check the measurements and pop the false fronts off, which might be a task in itself , and post some more photos

Or inches off the ground it is just under 31 inches x 11 inches x 11.5 inches

[LNBAudio]

Without seeing what's behind the false front, and going on dimensions and some construction cues, I'm guessing series I LNB ParaLab 20s
The dimensions should be around 31" x 11" x 11 1/4" and weight 40lbs. Behind the false front should be a KEF B200, a KEF T27 and a STC4001G.
The back is white melamine, which was quite expensive at the time, and the terminal block was made by Carr Fasteners of Nottingham (it still has it's red polarity spot)