Array's Sales

[ARRAY]

Here is a picture of the MH-35 tweeter

[ARRAY]

And of the model H-22

[ARRAY]

For sale are a pair of legendary Celestion / KEF "Turbo" Tweeters, originally developed for the BBC for use in their studios. Model HF1300 I beleive.

These drivers were used in Rogers, IMF, Fried, Celestion & KEF models.

Both tweeters are fully functional and in all-original condition. Ready for use. Comes with die-cut airseals.

$75/pr

[nyatt]

HI. I am interested in these. Do you take paypal? what would shipping be to Ca 94556 U.S.A.?
Thanks,
Matt

[consort_ee_um]

Good description of this device here on troels site:
http://www.troelsgravesen.dk/vintageBC1.htm
have to scroll down a bit
Not used by Kef by the way

[Jonathan Bright]

Some hope for people who missed buying them from ARRAY and a bit of background.
They are Celestion rather than KEF but they were frequently used as the tweeter above the KEF B139 and B110 in a number of DIY and IMF tranmission lines etc and that's where the link with KEF seems to comes in. Celestion no longer make them. A gentleman in England emailed me to the effect that the tooling for the HF1300 was sold by Celestion to COLES Electroacousitcs in the UK. I am not 100% sure but as I understand it they were originally the "compression" driver for a hornloaded tweeter system that was used with a very early 8" metal cone unit from GEC and that combination goes way back to the mid 1950's. I don't think that the BBC actually developed them. They liked them because they were 'flat' and "uncoloured". Early BBC monitors used them down to around 1500 c/s (with a 12" paper cone woofer) although their resonance is about 1700c/s. Generally all the commecial units ran them from 3 kHz. You can add at least two early B&W models to the list ARRAY mentioned too. Subsequently the BBC 3-way bextrene coned units of the 1960's and smaller monitors with 8" bass/mids used them. There are two versions, big and small magnet and two imepedences, 8 and 15 ohms.

Now the good news is that I think the current Coles 3000 is the same unit as the Celestion HF1300 with a different front plate. I was visiting their site a few days ago and you'll find it there along with the Coles 4001 which is the old STC4001. This is a super tweeter that was often used with the HF1300. It can run from around 6,000c/s. The HF1300 only goes to about 14/15,000 cycles and so people used to run 'super' tweeters on top of it. I have heard that the BBC never worried about the limited range as their FM broadcasts didn't go any higher so they didn't stress about the last half octave.

I'm sure that our English collegues will add/correct this data if they see this thread. I've owned both versions. My wife picked up a pair when on a business trip to the UK in 1978: still going well. BTW`way if you want the COLES`site enter COLES ELECTROACOUSTICS in Google. (Coles Acousitcs doesn't get anywhere)
Jonathan Bright

[pinkmouse]

Originally posted by Jonathan Bright
Now the good news is that I think the current Coles 3000 is the same unit as the Celestion HF1300 with a different front plate.

Quite correct.

The HF1300 only goes to about 14/15,000 cycles and so people used to run 'super' tweeters on top of it. I have heard that the BBC never worried about the limited range as their FM broadcasts didn't go any higher so they didn't stress about the last half octave.

Again quite correct, UK FM transmissions have never gone above 15K.

...Coles Acousitcs doesn't get anywhere...

Well, it woudn't would it?

[EC8010]

Originally posted by Jonathan Bright
I have heard that the BBC never worried about the limited range as their FM broadcasts didn't go any higher so they didn't stress about the last half octave.

As you say, the radio boys never worried, but once we went from 405 line television (introduced in 1936 as "high-definition" television) to 625 line television, the line frequency went up from 10.125kHz to 15.625kHz, and because floor monitors are common in TV studios, the microphones might pick up a whistling line scan transformer, so it was important that loudspeakers could reproduce 15.625kHz and reveal the problem. That's why there was a later generation of BBC monitor loudspeakers with the STC4001.

Actually, the reason why TV were worried about 15.625kHz is quite interesting. At the time, the BBC used a mono Sound-In-Syncs (SIS) digital audio system that put (and I'm stretching my memory here) 20 digits in each line sync pulse and sampled at 31.25kHz, making it a 10 bit system. Ten bits isn't enough for quality audio, so a companding system was used that added a 15.625kHz pilot tone to the signal before applying it to a compressor. The compressor reduced the level of the pilot tone, and at the SIS decoder, an AGC system was used to restore the correct pilot tone level, simultaneously expanding the audio. The interesting thing is that because the pilot tone was synchronised to the sample frequency, you really could carry fs/2.

[sreten]

Hi,

It should be mentioned it was the tweeter used in the
now legendary Spendor BC1 studio / home monitor, and
thus was very highly rated. And a number of Celestions,
including the very popular Ditton 15.

/sreten.

[consort_ee_um]

I think the Ditton 15 was designed by Laurie Fincham who went on to Kef. Amusing story here about keeping Thiele's work secret:
http://www.audioxpress.com/magsdirx/...-thiele105.pdf