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Atkinson compact transmission line speakers.

M

Martyn Miles

pfm Member
I have just picked up a pair of these surprisingly good speakers.
Kef B110 and Isophon KK8 drivers in a short transmission line.
The cabinets are solidly built, with plywood panels.
23cm wide x 26cm deep x 45cm high.

The sound ?
Linked up to my Nait 2, these are my initial feelings.
Open and clear with an unexpected bass response.
Piano is just ‘right’, with sufficient weight and openness.
The midrange is very similar to LS3/5as with Kef drivers.
Detail is well conveyed.

OK, the top is a little bright and they’ve not a ‘warm’ as some similar designs.
But they image well, not to LS3/5a standards, but good.
I paid less for them than what I could realise if I sold the B110s.

A rather nice find...
 
I have a copy of the Hi-Fi News article and I’m impressed by the detail.
Plywood, not just old chipboard.
Intricate diagrams to help.
The person who constructed these was very methodical.
I’ve seen commercial speakers less well built.
These are really growing on me.
That transmission line bass is unique.
 
@Martyn Miles,
Indeed, a nice find.

If the HF level matching resistor is mounted on back of the KK8, as per the HFN article, it shouldn't be too difficult to experiment with tweeter level without altering things too much.
 
stuwils said:
I had a pair and liked them, I liked the isophon kk8 tweeter.
Rgds
Stuart
Click to expand...
Agree, the main advantage was that they could be crossed over low (1 Khz) and frequency range with the hump in the B110 was avoided. Very elegant.

I also had the Bailey which was something else but SWMBO did not like the size so they did not stay very long :(, all that work for nought but the Atkinson mini line was a lot more work (fiddly).
 
I also used the Chris Rogers Hifi answers transmission lines for a few years but had to downsize due to a house change, moved on to ls3/5a for a bit but could not live with the lack of volume or bass, the atkinsons got around that for me and stayed for a bit before getting rogers export monitors which I loved.
Rgds
Stuart
 
Craig B said:
In which case, it would likely be best not to mess with the chosen tweeter resistor value, @Martyn Miles.
Click to expand...

It is much better to model crossovers in LtSpice since it comes up with (sometimes total) different values than when using the "standard" L-Pad calculators. The impact on the frequency curve can be viewed and adjusted if needed.

Unfortunately older drivers, more often than not, are missing complete data and "some" (?) reverse engineering of the data with some guesswork is needed.

In the end it all comes down how "sharp" the knee is at the crossover point of both mid-woofer and tweeter, the sharper the "knee" is the harder it becomes to adjust.
 
Last edited:
Craig B said:
@Martyn Miles,
Indeed, a nice find.

If the HF level matching resistor is mounted on back of the KK8, as per the HFN article, it shouldn't be too difficult to experiment with tweeter level without altering things too much.
Click to expand...

I wasn’t planning to do any experiments with these little Atkinson speakers.
They sound exceptionally good as they are.
 
I have been investigating some of the other transmission lines that P. Atkinson made.
He was quite a respected designer in his day.

My little ones are growing on me.
There are some similarities with the LS3/5a, but the bass end is different.
Perhaps less ‘warm’ and also a little more defined.
 
Martyn Miles said:
I have been investigating some of the other transmission lines that P. Atkinson made.
He was quite a respected designer in his day.

My little ones are growing on me.
There are some similarities with the LS3/5a, but the bass end is different.
Perhaps less ‘warm’ and also a little more defined.
Click to expand...

From what I remember is that it did not seem to have the bass hump.

The linked document does not say which B110 was used so I suspect it was the SP1003, I have forgotten. Did you take a look which one is in there?

The B110 was highly respected and even today it is hard to find something similar.

And no surprise on these growing on you, did not expect anything less. ;)
 
I have a photocopy of the original Hi-Fi News article and it states that the B110/SP1003 was chosen over its close
competitors.

The Isophon KK8 isn’t well known to me.
I realise now it was utilised in my Monitor Audio MA4s in the ‘70s.
They were rather ‘bright’ for me.

Some years later I refurbished a pair of Falcon Acoustics/Nightingale speakers, which used the
KK8 with an Audax bass/mid. driver.
They sounded excellent, not unlike my Spendor BC1s.
 
Martyn Miles said:
I have a photocopy of the original Hi-Fi News article and it states that the B110/SP1003 was chosen over its close
competitors.

The Isophon KK8 isn’t well known to me.
I realise now it was utilised in my Monitor Audio MA4s in the ‘70s.
They were rather ‘bright’ for me.

Some years later I refurbished a pair of Falcon Acoustics/Nightingale speakers, which used the
KK8 with an Audax bass/mid. driver.
They sounded excellent, not unlike my Spendor BC1s.
Click to expand...

Thanks.

We left these speakers behind when we emigrated to New Zealand: We had to cut down on what we could take with us with our allowance of how much we could ship. Then with kids didn't have the the money for serious stereo and later did not have the time to make speakers. And when production of the B110 stopped all thoughts of making them again disappeared too. And now health has intervened :mad: hence me buying the Q7's.
 
Martyn Miles said:
Of course they exist...
Just tell me how to get them on here and you’ll see them.
I have tried a few ways of loading them, but no success.
PM me your email address and I’ll send you some.
Click to expand...
Martyn, go to:
https://postimages.org/
1) Upload the image.
2) Copy the "Direct link" url.
3) Click the "Image" icon on your pfm text box (the one beside the smiley face!).
4) Paste in the url.
5) Click 'Insert'.

Job done! :)
 
Was it Atkinson or maybe Bailey who did the horn loaded Speakers with big horns built under the floor?
I think the mrs would flounce to come home and find that! I had the plans for all these transmission line type speaker around. The folder was an inch thick and lost during a house move.
 
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