WTD: Pair of Celestion HF2000 tweeters (must meet strict criteria)

[ToTo Man]

Just a thought, and I'm not trying to throw a spanner in the works, if you're placing the tweeters down on carpet (i've not seen the carpet, thickness etc) then there's a possibility that subsequent tweeters placed for testing may be tilted slightly in comparison, a carpet not being a stable, repeatable support. This off axis effect would adversely affect the level of signals received by the mic, giving rise to a false comparison. You may have taken this into account of course with how the tweeter is 'placed' on the carpet.

Very good point if you're rounding to 0.5db could make all the difference.

That is a good point, but I did try to get each one as levelled as possible to ensure consistency. I suppose a shift of a couple of degrees could affect the response by a few tenths of a dB, but most of the differences between the units I measured were of the order of a few dBs not tenths.

It wasn't so much the variations in overall output level that surprised me (these could easily be balanced with a resistor), but that some of the units had significant dips in their response. Luckily the two units I paired up as the best match for each other also happen to have the most linear response of all the units I tested.

[vintagesteve]

Out of interest, here's the polar response of the Ditton 66 if you haven't already got it. Well, it would be here but it seems there's no facility to upload images any more!

[ToTo Man]

Out of interest, here's the polar response of the Ditton 66 if you haven't already got it. Well, it would be here but it seems there's no facility to upload images any more!

This?

[vintagesteve]

That's the one, yes.

[ToTo Man]

There doesn't seem to be much affect on the HF response for the first few degrees or so, therefore my measurements should all be comparable.

[ToTo Man]

Bump (still looking for a matched pair of HF2000s).

[ToTo Man]

Another bump to say I'm still looking for HF2000 tweeters. I'm now willing to consider unmatched pairs or single units, in the hope that I might be able to match them up with the units I already have.

[spendorman]

I had a similar problem finding a pair of HF2000s for my LS3/6.

I believe that there are different impedance versions too.

[spendorman]

Interesting

https://www.ebay.co.uk/itm/Pair-of-C...bxQg:rk:4:pf:0

[ToTo Man]

Interesting

https://www.ebay.co.uk/itm/Pair-of-C...bxQg:rk:4:pf:0

Nice find! .

One of the pairs of HF2000 I bought from eBay were NOS and came in the same boxes as shown in the above advert. I couldn't believe my luck, that was until I frequency swept them and discovered they were out by 4dB at certain frequencies .

In my experience, from the dozen units I've measured (graphs here), I struggle to draw a conclusive relationship between their DC resistance and their actual sensitivity. The DCRs of the units I measured range from 3.3 ohms to 4.4 ohms. The units in the above auction have DCRs of around 6 ohms, which would suggest a significantly higher nominal impedance than my existing units. I'm not sure how this would affect the Ditton 66 crossover circuit??