TANNOY 3128 speaker 1012 and HPD315A crossover. What's the difference?

[cooky]

Yeah, they're significantly improved: faster, tighter, seemingly more extended in the bass, more detailed/less coloured elsewhere, I guess because the drivers are now behaving as they were designed.

Anyway, if I can help at all with framing, you know where I am. Also, if you'd like to link to your Facebook page, in your signature here, feel free to do so. Might help generate some more interest in your artwork

Marco.

Agreed on the Cants-thing is they weren't as 'gone' as some I've seen but just goes to show a tacky surround is a knackered surround...

On the arty front that's most kind of you-I'm in the process of sorting web stuff out at the mo'-the FB page is a mess ;-)

[walpurgis]

Here is the SRM 12X crossover diagram, which I suspect would be largely similar. The drivers share many parts. I think the main difference is the cone and surround.

You would need to establish the values across the tapped inductor. They can be measured if anybody has one handy.

[Reffc]

The information posted comes from Tannoy. The letter is reproduced on Han's site.

Usual caveats in place of course but here's Phil Shorts investigations into tweaking the short horn DC's..http://www.hilberink.nl/codehans/tannoy53.htm

Alas, that doesn't make it right, neither is it right! Ahhh, the perils of t'ut interweb

The explanation for the autoformers given there isn't strictly correct either. They were there to impedance match the drive units, not just for reasons of energy which can be got around by other means. Also, the input (green) winding of the input is most certainly not 4mH to ground. That is one of those errors which has plagued Tannoy internet crossover schematics and now I see where it originated! The LF value commonly ascribed to 315 HPDs is also wrong. It is not 1.2mH. It may be for the ceramic magnet version (but that I doubt) but it is most certainly the wrong value for the HPDs.

Again, Tannoy never originally published T&S specs because they simply didn't exist at the time and the letter refers to the values for the HPD, provided many years after the fact. It very much looks like the person who wrote that letter just assumed that the later ones would be the same. They can't be unless someone re-wrote the laws of physics in the intervening period. That can be proved. How can you have the same T&S parameters when different magnets and different horns were used? The Fs differs, the BL factors differs etc etc etc.

You can sometimes lead a horse to water but when people keep on insisting that duff information is correct, I have to shake my head and just give up. Hopefully people looking in will not be tempted to run with information gleaned from sources which do not ascribe the true values to fact (ie measurement).

[Reffc]

Here is the SRM 12X crossover diagram, which I suspect would be largely similar. The drivers share many parts. I think the main difference is the cone and surround.

You would need to establish the values across the tapped inductor. They can be measured if anybody has one handy.

May I ask where that came from Geoff? The values look about right and I do have the values for the tappings should anyone require them.

[walpurgis]

May I ask where that came from Geoff? The values look about right and I do have the values for the tappings should anyone require them.

I'm afraid I don't remember Paul. It was stashed away in the PC's files. I obviously kept it in case I wanted to replicate the circuit. Those tapping values might be handy.

[cooky]

Alas, that doesn't make it right, neither is it right! Ahhh, the perils of t'ut interweb



Again, Tannoy never originally published T&S specs because they simply didn't exist at the time and the letter refers to the values for the HPD, provided many years after the fact. It very much looks like the person who wrote that letter just assumed that the later ones would be the same. They can't be unless someone re-wrote the laws of physics in the intervening period. That can be proved. How can you have the same T&S parameters when different magnets and different horns were used? The Fs differs, the BL factors differs etc etc etc.

You can sometimes lead a horse to water but when people keep on insisting that duff information is correct, I have to shake my head and just give up. Hopefully people looking in will not be tempted to run with information gleaned from sources which do not ascribe the true values to fact (ie measurement).

With respect, I'm attempting a dialogue here. Anyone dipping into this thread will be wondering why, rather than shaking your head you don't produce your 'correct' T&S parameters for the HPD and K series to back up your assertion/contradiction of the Tannoy numbers.
What we have is cone/surround/spider/vc assemblies common across the 2 ranges so we know Mms, Cms, Re, Rms, Sd, and Le, it would be interesting to know if in redesigning their ceramic motors Tannoy achieved similar BL figures to the AlNiCo's-much like JBL did when they had to make a similar move;
When JBL were forced to abandon AlNiCo they redeveloped the 2231a driver-it's replacement was the ceramic 2235-Same cone/surround/mass ring/voice coil but a progressive spider which altered the compliance, other than a different Vas the T&S are very similar with BL of 21 and 20.5 respectively and Fs around 18hz-maybe JBL rewrote the laws of physics;-).

[struth]

With respect, Paul is in business and works hard to get the info he has. I dont blame him if he wants to keep his measurements to himself.

[cooky]

With respect, Paul is in business and works hard to get the info he has. I dont blame him if he wants to keep his measurements to himself.

I'm just a horse looking for a drink of water mate.

[Reffc]

With respect, Paul is in business and works hard to get the info he has. I dont blame him if he wants to keep his measurements to himself.

Thanks Grant.

As you're aware, I don't have to offer any justification (my information is sound) so I won't rise to the bait. There's always those on these forums waiting to creep out of the woodwork and argue with no real knowledge or basis for their ill conceived arguments.

As far as Tony's dilemma is concerned, I have a possible solution for him if he'd like to contact me privately to take this one off-air as it's just a waste of time for everyone concerned otherwise. Geoff, if you need the tapping values, please PM me and I'll supply them for you.

[cooky]

Thanks Grant.

As you're aware, I don't have to offer any justification (my information is sound) so I won't rise to the bait. There's always those on these forums waiting to creep out of the woodwork and argue with no real knowledge or basis for their ill conceived arguments.

I haven't posted one single piece of duff info,.
So far you recommended a crossover for it's 'time compensation' that didn't include any, stated the HPD/3** have different cones, different voice coils-wrong again, stated that to design a ceramic magnet using the same cone/coil/spider to have the same BL as an AlNiCo magnet goes against the laws of physics-wrong again.
If you have info that contradicts the Tannoy published T&S information-not sure which you are saying is wrong btw, the K series or the HPD..in any case given the number of Tannoy enthusiasts there are around that could enjoy the benefit, your refusal to share it says plenty.
Given the age of these drivers-in particular the HPD with it's AlNiCo mag I'm surprised there aren't lots of independent T&S measurements on the web-that said the nature of the beasts means those measurements are only good for that individual driver and any figures shown wouldn't have any commercial value.
While were on the subject of no real knowledge on the Tannoy Legacy thread you state the Legacy cabs with the TW(tulip waveguide) drivers will need time compensation and a notch filter-utterly wrong. The TW are time aligned and the horn uses a low compression waveguide-it doesn't have the resonance present in the pepperpots throat.
In the £3k xta sourced Tannoy pro digital crossover for these tulip DC drivers no LF time delay is applied and any peq is very wide band and gentle on the hf-no notch required.