Hello,
Recently, a good friend gave me two woofer 12 inches "Richard Allan Super HP 12B 8 ohms", never used! still in the box!
(He gave me also two "Decca London Ribbon Tweeter"...... In their boxes too.....)
The 12B wont stay in their boxes for a long time. I focus on them but I can not find the thiele-small parameters, bandwidth curve ect and to pay tribute to those speakers those informations are indispensables.
Your help will be very appreciated
Thank you
Recently, a good friend gave me two woofer 12 inches "Richard Allan Super HP 12B 8 ohms", never used! still in the box!
(He gave me also two "Decca London Ribbon Tweeter"...... In their boxes too.....)
The 12B wont stay in their boxes for a long time. I focus on them but I can not find the thiele-small parameters, bandwidth curve ect and to pay tribute to those speakers those informations are indispensables.
Your help will be very appreciated
Thank you
Lucky you
Richard Allan made very nice drivers, and new in boxes!!...are those 12" with coated paper cone, red surround and gold chassis or the later ordinary poly ones
Be carefull with the Decca ribbons, they are fragile and should be handled with care, should be crossed rather highish so you will need a wideband midrange...I believe they are quite rare now a days so please dont "burn" them, they are not very happy playing too loud...but if you dont feel like using them you should be able to get a good price...but I have no clew how much
Richard Allan was my first real highend speaker
would really like to see some pictures, if possible
Richard Allan made very nice drivers, and new in boxes!!...are those 12" with coated paper cone, red surround and gold chassis or the later ordinary poly ones
Be carefull with the Decca ribbons, they are fragile and should be handled with care, should be crossed rather highish so you will need a wideband midrange...I believe they are quite rare now a days so please dont "burn" them, they are not very happy playing too loud...but if you dont feel like using them you should be able to get a good price...but I have no clew how much
Richard Allan was my first real highend speaker
would really like to see some pictures, if possible
I bought a couple of the ordinary HP12B drivers last year (not the -Super version), but I've not yet measured their TS parameters to see how they match the data in the table.
I use their excellent HP8B units, two in 34 litre sealed boxes, and another two in 62 litre transmission-line enclosures. Both work extremely well.
I have measured the HP8B TS parameters, (though I don't have them at hand), and the Fs was very different from the published data. I remember that I measured an average of 33Hz across four units, compared with the published 24Hz. I really ought to re-check the units in the sealed box speakers, as these are the ones I use every day, and see if regular use has dropped the Fs.
I use their excellent HP8B units, two in 34 litre sealed boxes, and another two in 62 litre transmission-line enclosures. Both work extremely well.
I have measured the HP8B TS parameters, (though I don't have them at hand), and the Fs was very different from the published data. I remember that I measured an average of 33Hz across four units, compared with the published 24Hz. I really ought to re-check the units in the sealed box speakers, as these are the ones I use every day, and see if regular use has dropped the Fs.
Richard Allan Super 12B
Thank you both of you, Tinitus & Ouroboros for your interest in my project. Ouroboros, if you have an opportunity to conform me the data, it will be very appreciated. One of my default but also a quality: I vest 200% of my self in a project (whatever the project) when I know what I do.
Thank You again
I add fews pictures of my treasure.
Thank you both of you, Tinitus & Ouroboros for your interest in my project. Ouroboros, if you have an opportunity to conform me the data, it will be very appreciated. One of my default but also a quality: I vest 200% of my self in a project (whatever the project) when I know what I do.
Thank You again
I add fews pictures of my treasure.
ClaudioB said:
I figure the Deccas are the score in that batch
Typically (at least over here) XOed at 1.6kHz 3rd order.
I got the opportunity to tweak out a set of prototype standmount Decca speakers -- 8" plus the Ribbon XOed at ~1k. (a wonderful all night listening session insued (NAIM 250/LP12))
Th eribbons are delicate, but exchanges can be had from Howard Dawson (link to a piece on XOs).
http://hd-audio.orpheusweb.co.uk/maxlife.html
Now if you'd like to sell them cheap...
dave
Attachments
I've measured one of my HP12B units using the LIMP program (part of ARTA) using the added mass method.
(I hadn't realised how difficult it is to get consistent results on a large heavy-coned speaker using the added-mass method!)
Anyway, once I had positioned the speaker so that I was getting consistent measurements I got:
Fs 28.8Hz
Qts 0.36
VAS 138 litres
Mms 80g
Qes 0.42
Qms 2.26
Rms 6.5 kg/S
Cms 0.4mm/N.
I was using an added mass of 25.4 grammes, comprised of a toroid of Blu-Tak pressed onto the cone around the dust cap.
This was with an HP12B (not the -super) unit that has been in storage for a few years, so really I should run it in with an LF signal for an hour or two so that the suspension can get the sleep out of its eyes!
(I hadn't realised how difficult it is to get consistent results on a large heavy-coned speaker using the added-mass method!)
Anyway, once I had positioned the speaker so that I was getting consistent measurements I got:
Fs 28.8Hz
Qts 0.36
VAS 138 litres
Mms 80g
Qes 0.42
Qms 2.26
Rms 6.5 kg/S
Cms 0.4mm/N.
I was using an added mass of 25.4 grammes, comprised of a toroid of Blu-Tak pressed onto the cone around the dust cap.
This was with an HP12B (not the -super) unit that has been in storage for a few years, so really I should run it in with an LF signal for an hour or two so that the suspension can get the sleep out of its eyes!
Ouroboros: thank you. I hope I will have the opportunity to send you back the elevator or to help somebody on the forum. I will see the program that you are taking about, ARTA. The only technic that I know for speaker's measurements are the one with a multimeter-sinewave generator-resistor... I have started my own test of the Super 12B, between the time I spend with my kids/the work/all others things. I will let you know the result.
Thank you again!
Thank you again!
Hi Claudio, If you are adding mass to the cone to get the second (lower) resonant frequency that you need in order to calculate the VAS, then it is important to place the speaker on a block of foam rubber or something similar that will not pass vibrations through it. (You could hang the speaker up by a length of cord instead I guess). I found that the VAS figure that ARTA calculated would vary by a large amount if the speaker was not mounted securely. Also it is important that the added mass cannot 'rattle', which is why I used the ring of BluTak. I'm sure you can use something similar, (although you need some accurate weighing scales to get an accurate reading of the mass).
Those London Deccas are rubbish, I'll take them off you if you like and even pay postage!
Only joking!!!
Here's some info on them:
Ribbon Tweeter Horn Loudspeaker: Decca London/Stanley Kelly - Efficiency, Size, Filter and Frequency Response.
And should you use them and eventually need new ribbons this guy can help:
Howard Dawson Audio - home page
Only joking!!!
Here's some info on them:
Ribbon Tweeter Horn Loudspeaker: Decca London/Stanley Kelly - Efficiency, Size, Filter and Frequency Response.
And should you use them and eventually need new ribbons this guy can help:
Howard Dawson Audio - home page
I believe they were rated for 25W continuous operation. A bit like the Goodmans Audiom 51/61 and other speakers of that era, they're really intended for fairly low-power amplifiers.
If you're putting them on Ebay (and you're in the UK) I'd appreciate you letting me know.
Thanks.
DECCA LONDON ribbon tweeters - by Rudolf A. Bruil
Ribbon Tweeter Horn Loudspeaker: Decca London/Stanley Kelly - Efficiency, Size, Filter and Frequency Response.
Ribbon Tweeter Horn Loudspeaker: Decca London/Stanley Kelly - Efficiency, Size, Filter and Frequency Response.
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