HF upgrade for HB1

[Sparks]

Hi all

I've recently sorted out the bottoms on a pair of HB1 mk1s and now feel the tops could now do with some "refining".

They still have the original X/O and tweeter in, what are my options regarding component/driver replacement?

Cheers
Sparks

[Cobblers]

http://www.puresound.info/id2.html


Take a butchers!

[Sparks]

Had a mail back from Guy, suggested leaving the driver as it is and replacing the X/O caps.

I'll have a go, but I suspect that might not have the desired taming affect, so I've plumped for a pair of
http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWN:IT&ih=007
to see how they work out.

Anyone have any experiences with them?
I figure £18 for a pair of ribbons
Even if they're no match, I can always use them for surrounds...


Cheers
Sparks

[Cobblers]

Originally Posted by Sparks

Had a mail back from Guy, suggested leaving the driver as it is and replacing the X/O caps.

I'll have a go, but I suspect that might not have the desired taming affect, so I've plumped for a pair of
http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWN:IT&ih=007
to see how they work out.

Anyone have any experiences with them?
I figure £18 for a pair of ribbons
Even if they're no match, I can always use them for surrounds...


Cheers
Sparks

Not a good idea.
The dispersion characteristics, driver and crossover will not suit.

Why not add a very small value resistor in series with the tweeter. Someone much more knowledgeable will be able to help.

[pre65]

Originally Posted by Sparks

I figure £18 for a pair of ribbons
Cheers
Sparks

I would think that they are sold singly !!

If you check the qty sold so far to each user 2 - 2 -3 - 2 - 1

which seems odd ?




Philip

[Cobblers]

Originally Posted by pre65

I would think that they are sold singly !!

If you check the qty sold so far to each user 2 - 2 -3 - 2 - 1

which seems odd ?




Philip

Yes,
It does say Tweeter not tweeter's'

Are you expecting to use them as super tweeters or regular tweeter?

If super tweeter this option will increase treble emphasis, the last thing you want.

Given the age of the speaker a cap change should be quite useful (with a polyprop cap -look at WD cap's), I would try that first.

[Sparks]

...ah, yes, the old Single Item Ploy :p (If it's any good I'll get another one, if it's pants I'll not have spent twice as much finding out )

Anyhoo, if I'm going to be messing with the X/O I might as well re-do it for this driver. (Will the caps have deteriorated? They look like polys, I thought only electrolytics were degradable?)

The website recommends a 5K/2nd order as a lower limit, the HB1s are crossed at 4K, (http://downloads.hifiengine.com/down...ybrook_hb1.pdf even though the bass unit range is quoted at 25-3K? https://secure.wilmslow-audio.co.uk/...roducts_id/154 ), so there's all sorts of possibilities (like taking out the low-pass etc.) I'll have to do a measure/listen. Anyone got any plots for the Vifa M21?

As for the dispersion characteristics, I figure it will be more controlled in the vertical plane than the hemispherical radiation of the D25 dome?

The sensitivity is 8db up at 98dB, but that can be padded down.

I'm going to try it in place of the D25, not put both in. I'm also going to try the HB1s with the Tonigens from my main setup (the marvelous World Designs KLS1s !)


Cheers
Sparks

[Cobblers]

If you have poly's already keep 'em.

HB1's always sounded good to me, despite the high crossover.

It sounds like 4khz was pushing it(as you can see from spec's) so why would you want to push it further to 5k?

If anything I expect you could get a smoother sound dropping to 2-3 khz with a high quality soft dome.
I think it is a mistake to try to move the crossover right out of the band where the ear is most sensitive if this means forcing a driver to work where it isn't at all happy (at all costs).


As for the Tonigen you need a small midrange driver to meet it seamlessly at 6khz upwards.

half inched from this very forum:


"Noel, in the June 1993 HFW DIY Supplement regarding the Tonigen he used in the KLS1, wrote:
"The (1.5uF) capacitor gives it a net flat frequency response ... and full output from 6kHz up to 20kHz exactly above which output drops like a stone."
He also mentioned:
"six ohms pure resistance" and "sensitivity of 87dB".



Five years later, in the April 1998 Supplement, the Tonigen is tested without a crossover by Noel using a sweep from 500Hz to 50kHz. The graph clearly shows a sharp dive in response above 20kHz, the quoted impedance and sensitivity differ in this later article though:
"Considerably flatter than a conventional dome tweeter, it runs smoothly from 6kHz to 20kHz ... This one delivers no less than 92.5dB sound pressure level from 2.8v input ... To achieve this Tonigen have used a low impedance of four ohms"
The corresponding impedance plot is ruler flat."

[Greg.]

Surely with Peter Comeau ('Petercom' here) being the original designer and developer of the HB1's, would it not make sense to pick up the phone to WD and discuss this with him? An interesting thread, but I doubt there are many questions you could pose on this that Peter could or would not answer.

[Cobblers]

Originally Posted by Greg.

Surely with Peter Comeau ('Petercom' here) being the original designer and developer of the HB1's, would it not make sense to pick up the phone to WD and discuss this with him? An interesting thread, but I doubt there are many questions you could pose on this that Peter could or would not answer.

Despite my waffling, I also think this is the best thing to do.