Large speakers (as in large)

Richard, I think the pics are later Hartley Luth. Best lookers and should sound as good as they look.

[Scottmoose]

Keep 'em coming guys... Richard, I apologise for mentioning Tannoy; I own a pair of Gold drivers, + plans for most of the enclosures, it was a bad example. That's why I also mentioned Goodmans and Wharefedale. Being a little more specific, to grab a couple of examples, something on the lines of Wharfedale's Airedale (and BTW, has anyone ever seen a review of these current range-toppers?) or a Tannoy Canterbury or vertically stretched corner Lancaster was what I had in mind in solely proportional terms. I like the corner types myself -more domestically acceptable.

Toppsy -yes. Pretty big. To an extent. You're talking to a person with 2 pairs of 6ft tall cabinets in his listening room, one QW loaded, the other corner horns.

[petercom]

Great, a very positive response so far. The design is already on the drawing board!

[Scottmoose]

Originally Posted by petercom

Great, a very positive response so far. The design is already on the drawing board!

Aha! Peter, you are The Man! I look forward to seeing the results. By the way, I meant to ask you before: would it be possible to use the drivers & crossover from the existing WD25 in a different enclosure without messing things up? I've spent too long with full-range drivers, so my multi-way knowledge, particularly re crossovers is practically 0.

Regards
Scott

[petercom]

Originally Posted by Scottmoose

By the way, I meant to ask you before: would it be possible to use the drivers & crossover from the existing WD25 in a different enclosure without messing things up? I've spent too long with full-range drivers, so my multi-way knowledge, particularly re crossovers is practically 0.

Regards
Scott

You can, though you are on your own if you do! Of course if you keep to the same internal volumes and use the identical aperiodic vent and foam (we supply the latter with the driver kit) then you can expect good results.

The critical parts as far as the crossover is concerned are the bass loading, defined by the internal volume and aperiodic vent, and the baffle width. Both of those are taken into account by the crossover in order to balance midrange to bass output.

Having said that the baffle is already fairly wide so you could take some liberties here as the baffle 'step' in the response occurs much lower than the crossover. And for bass to midrange balance all you need to do is alter the value of the bass series coil as I have outlined in the 'upgrade' articles in HFW recently.

What did you have in mind?

[Scottmoose]

Hi Peter, many thanks for the reply / advice

You're going to laugh me off the board with this no doubt, but, er, a corner Tannoy Lancaster cabinet, believe it or not, modified with a 3in diameter x 4in long port replacing the original vent. Internal height is 33in, and I calculated a top and bottom area of 240.5in^2. Front flat baffle is 17 1/2in wide, with two additional side extensions, sloping back (I'm sure you know the style) approx 4in. The MathCad predicted 1/2 space response for the Seas A26 (assuming the published T/S parameters are accurate) in that enclosure looks like this, which I didn't think looked too shabby, which is why I wondered if you thought the existing crossover etc might work, albeit with some modifications.
Best regards
Scott

[petercom]

I calculate this to be a 130 litre volume. That's a LARGE speaker.

Attached are the LspCAD plots of ported (br) and closed box (ib). If you try and port this unit in such a large volume you end up with a lift of 1 - 2dB below 120Hz. Add this to the corner lift of 3db (increasing to 6dB as you go below 60Hz) and the bass may become overwhelming.

That's why I said use the aperiodic vent. With a Qts of 0.41 you can either make it a closed box system (simulation attached) or try filling the vent with open cell (reticulated) foam. Either way you need to adjust the damping by ear to get the balance right. You'll also have better bass clarity than a boom box.

[smithy]

I built a pair of the Falcon Maximus Focal kits using 15 inch Audiom bass units I vowed never to build another pair of speakers again .Double thickness 3/4 mdf,a lot of work but I dont regret it,a sense of scale that you just dont get with your average 8 inch containing box.Trouble is they are not very domestically acceptable,but if you are single or have an understanding wife give it a go.Trouble is deciding which big bass unit to go for these days as the choice is getting more and more limited.If you are going to build a big one you need IMHO a decent 15 incher to underpin it all.

[Black Stuart]

That's exactly right Smithy, 15" woofers are indeed hard to find, can you supply specs for the Axiom one. I was hoping to buy a s/hand pair of Beymas but something tells me not to trust the vendor in Vascaya. I shall hope that another pair become avaiable - 4 Ohm/101dB/30hZ.

Black Stuart

[Scottmoose]

Originally Posted by petercom

I calculate this to be a 130 litre volume. That's a LARGE speaker.

Attached are the LspCAD plots of ported (br) and closed box (ib). If you try and port this unit in such a large volume you end up with a lift of 1 - 2dB below 120Hz. Add this to the corner lift of 3db (increasing to 6dB as you go below 60Hz) and the bass may become overwhelming.

That's why I said use the aperiodic vent. With a Qts of 0.41 you can either make it a closed box system (simulation attached) or try filling the vent with open cell (reticulated) foam. Either way you need to adjust the damping by ear to get the balance right. You'll also have better bass clarity than a boom box.

Many thanks for that Peter -it's not many people who'd instantly run a couple of check-sims in LspCAD for someone. Much appreciated. The aperiodic vent option looks the most interesting to me (surprise!)...