My first Dipole Subwoofer!!!

[Nuuk]

Thanks for the comments guys.

Simon, you do raise a few doubts although I am not sure if the Beta 15 is designed for a sealed box or not.

Spending a bit more on what though? There are slightly more expensive Eminence drivers or we are looking at prices nearly double that of the Beta15.

Now if only we had flea markets like the ones Joe goes to!

[leadbelly]

Personally, I'm not too crazy about the drivers you chose (begin flame here ). For that kind of money, you should be able to find either a very low Fs or a very high Qts driver. With Fs about 40 and Qts about 0.5, you need to do plenty of EQing.

[SimontY]

I am not sure if the Beta 15 is designed for a sealed box or not.

You are quite right in that it's unsuitable for a sealed box, this was my first audio project of any kind, and it went a bit wrong

It was meant to be a sub, but only managed to cover the same sort of range as my stand-mount speakers! (B&W DM602 at that time). The bass being sloppy was largely due, no doubt, to the box Q being too high. To work properly I think it needs an insanely large box.

I honestly don't know the purpose of this driver. Maybe for a cheap bass guitar box it would work ok. Maybe for open baffles it would be good!!

My thoughts about big bass drivers are shaped by this and its replacement - Adire Tempest. This is cheap, before shipping from the US Even at the price it cost me in the end, it's so superior in every way as to be easily worth so much more money.

As I see it, a 15" driver is likely to have a large voice coil and moving mass, etc. But they don't always have a magnetic force/size that scales up with that large cone etc. I think this is why most big drivers produce uncontrolled bass. Shoot me if I'm wrong, I barely understand all this...!

What you and I both need, is something like Adire (cheap, maybe poor QC, but very good products) in the UK!!!


-Simon

[Nuuk]

Personally, I'm not too crazy about the drivers you chose (begin flame here ). For that kind of money, you should be able to find either a very low Fs or a very high Qts driver. With Fs about 40 and Qts about 0.5, you need to do plenty of EQing.

Thanks leadbelly. I am not over-excited about these drivers either but it just illustrates the pathetic choice that we have here in the UK!

As SimontY says, it is probably best to source something in the USA and ship it over but the thought of shipping costs for four 15 inch woofers is a bit offputting!

After another look on Parts Express, a couple of the Dayton woofers look good, particularly the Quatro (4 ohm):

Specifications: *Power Handling: 300 watts RMS/600 watts max *VCdia: 2-1/2" *Le: 3.5 mH *Znom: 4 ohms *Re: 3.45 ohms *Frequency range: 20-125 Hz *Magnet weight: 67 oz. *Fs: 21 Hz *SPL: 91.8 dB 2.83V/1m *Vas: 6.60 cu. ft. *Qms: 14.0 *Qes: .42 *Qts: .41 *Xmax: 10 mm *Dimensions: A: 15-1/8", B: 13-7/8", C: 6-5/8".

OTOH if those Pyle drivers work as well as Chops says (and I have no reason to doubt him), does anyone know if they are still available, and if so where from?

[richie00boy]

SimontY,

As I see it, a 15" driver is likely to have a large voice coil and moving mass, etc. But they don't always have a magnetic force/size that scales up with that large cone etc. I think this is why most big drivers produce uncontrolled bass. Shoot me if I'm wrong, I barely understand all this...!

I see your logic, but the tightness of bass isn't really that much to do with how big a magnet looks. The Qts paramter is the key to how tight the bass will be. In the case of the Eminence driver you gave matttcattt, this is quite high which is why it needs a big box. For open baffles, you need the Qts to be quite high as there will not be a box loading against the driver (which raises Q).

BTW, I am helping matttcatt with his sub, I think he is quite barmy

Nuuk,

I'm interested in open baffles myself having played with subs for a while now. Where did you find the Eminence Beta 15 at that price? I have my eye on some cheap 15 inchers in the CPC catalogue, but they don't have any real specs Maybe I will visit you after all

[SimontY]

the tightness of bass isn't really that much to do with how big a mag

I said how big it *is*, not looks! hehe. Well, there does seem to be a correlation with good sound and large magnets. But I realise the useful field strength will have just as much to do with fine design details and the type and 'quality' of the magnets as it will their size.

The Qts paramter is the key to how tight the bass will be.

Thanks for pointing that out for me.

I am helping matttcatt with his sub, I think he is quite barmy

Heh, I got that impression myself!

Where did you find the Eminence Beta 15 at that price?

It wasn't Maplins was it??

the Dayton woofers look good

Those look like really good specs! Sensitive and good xmax! (unless thats p-p and not one way...)

As SimontY says, it is probably best to source something in the USA

That's not what I said but what I did, and I don't reccommend it. My first driver came with a fault, and it took months to arrive in the first place. They were good about replacing it to be fair. Import tax was a slap in the face, and shipping was something mental like $65!!! It just isn't economical. Its about time Adire Audio got a UK distributer. Just business from diyaudio members would make it worthwhile IMO. I have never seen *anything* like the Shiva and Tempest in the UK... If someone knows of these sorts of products here in the UK, please let us in on the secret!!

Thanks!

-Simon

[tcpip]

Originally posted by Nuuk
...and the only one that I can find (that has specs) that is sort of suitable is the Eminence Beta 15.

What's the difference between this one and the Eminence Pro series? I remember a discussion in this forum somewhere where one member painstakingly pointed out that symmetric magnetic field or some such high-tech feature of woofers sharply reduce distortion at higher excursions. And IIRC, he'd said that the Eminence Pro range has this feature.

Is this relevant in this case? Just curious; I understand very little of all this.

Tarun

[Nuuk]

Where did you find the Eminence Beta 15 at that price? I have my eye on some cheap 15 inchers in the CPC catalogue, but they don't have any real specs Maybe I will visit you after all

Richie,

I found the best prices at BK Electronics BUT if you look at the Maplin prices for 5 units, and remember that there is no carriage charge, it is almost as cheap to buy 5, as 4 from BK!

I've looked right through the CPC catalogue but the lack of specs is a sick joke. When I did my full-range open baffle experiment (see HERE ) I contacted CPC for specs but the helpful(?) lady I corresponded with thought that T?S parameters were just size and weight! I gave up after four emails.

Yes, we definitely need somebody like Adire to appoint a UK dealer. Or I wonder how much of an advantage we could gain by getting enough of us to order the same driver! Come on you Brits - who wants some decent 15 inch woofers?

I've plenty of tea and coffee if you do feel like popping over some time!

Tarun - Mr Linkwitz talks about an Eminence protoype on his site. I wonder if this is now part of the Eminence range, or something that we can expect in the future (and specifically designed for OB's).

[richie00boy]

Checked out your site (briefly) - few interesting things on there

I'm actually happy with my system, but like to try stuff out. I like the idea behind open baffles, but I don't actually think they'd give me the sound I'm after - I like my sound solid and maybe a bit punchy. However, I'd still like to try OBs just to see what they're like, especially if I could utilise some of the drivers I've got laying around, or buy cheap ones.

Also, the sound I have is great, but only in one seat in the room, and I had to move stuff around to get it like that. I reckon OBs would be more tolerant?

Plus I also get a buzz from friends jaws dropping when I tell them I designed and built it

I'm aware of BK, got stuff from them in the past. I reckon I'd be interested in a group buy of the Eminence or similar...

I'm fairly new to this daan saarf lark, so don't have my bearings sorted out yet, but I dare say a visit may be on the cards soonish...

[Nuuk]

Also, the sound I have is great, but only in one seat in the room, and I had to move stuff around to get it like that. I reckon OBs would be more tolerant?

Mine is similar I'm afraid. It depends a lot on what drivers you use. With my 12 inch full-range drivers there is some inevitable beaming at higher frequencies. However, the positives far out-weigh the negatives (and I live on my own)!

Well. let's see if we can get a group buy for something better than the Eminence.

I'm fairly new to this daan saarf lark, so don't have my bearings sorted out yet, but I dare say a visit may be on the cards soonish...

Well, I'm five minutes from junction 22 on the M5 if that helps.