Supravox and/or Tone Tubby OB

[zmyrna]

I have been obsessing about building my own OB speakers for the last few months. The DIY project on Supravox website, Mr Lampizator, and JVH's Lowther+Tone Tubby OB are my inspirations.
It will be great if I can do without a tweeter or a double cone. I can always add a supertweeter, if need be. Among full range drivers, I have looked into Supravox 215 sig and Tone Tubby 8" ceramic. Both have probably too much mid rise, and beam like hell. My current favorite is Supravox 165 gmf which will need to be supplemented by a midbass.
I need your advice on the crossover point and the selection of midbass driver.
My midbass candidates are:
1. Tone Tubby 12" alnico
2. Tone Tubby Superboy 15"
3. Supravox 285 gmf
Superboy and 285 gmf are about 99db/1W sensitive and 12" alnico is 97.3db. Considering 165 gmf is 96db, can I get away with just an inductor on the midbass and nothing on the 165 gmf?
I am planning a 40-50cm wide, 110-120cm tall baffle with deep and angled wings at the bottom half, and the midbass sitting as low as possible.
My amp is a 150w digital TacT unit and I also have a REL sub just in case.
I can't wait to hear your opinions.

[zmyrna]

BTW, attached is the Tone Tubby 12 alnico specs and 8 ceramic responce curve (it is actually Hemptone ER8 I think, which is very similar).

And here is 12 alnico's response curve
The 12" Alnico Tone Tubby

Supravox specs and curves can be found at Bienvenue chez SUPRAVOX

[nullspace]

I have some experience with the ToneTubby 12", so I can speak to that driver... I would think you could do a reasonable impression of the Lowther OB with the Supravox filling in for the Lowther driver. If it were me, I'd take a good, hard look at the crossover JVH did and work towards replicating it for your drivers. Be warned, though: you'll ned that REL with this arrangement -- I don't think it's incidental that JVH was showing the OB this year with a different driver, Altec 15" of some sort I think, and biamping IIRC.

Regards,
John

[zmyrna]

John, thank you for your response.
I have read about your speakers in forums, very cool.
I am aiming at a minimalist version of what you have done.
My HF hearing is not very good (I am also very sensitive to HF problems!?!), that is why I am not going compression driver/horn route.
JVH's XO (and yours as well on that matter) is a bit too complex for me.

[zmyrna]

Since JVH has switched to an 15"er now, what do you think about the 15"ers in my list?
The 12 has the advantage of being alnico. Many people think that alnicos have a very sweet tone. However, some think the difference is not that significant with solid state amplification (and for that matter probably digital as well).
On the other hand 15" would go lower (obviously) and blend better with the sub.
Forum member Painkiller thinks that TT alnico and Superboy sound very similar.
Would Superboy be a good match to 165 GMF? Or should one stick to an all Supravox arrangement? (more expensive option though)
The sensitivity of the 15"ers in my list is probably a better match to 165 GMF as well.
And yet again Chopper87 from audiocircle believes that the only midbass that does not muddy the midrange (in a similar Lowther+woofer OB) is the TT 12" alnico

3 years and 8 Open Baffles later.

John:
What exactly is the benefit of having so many pieces in the XO?
The drivers in my list seem to have quite flat responses as they are (in the range they will be used at least).
If the sensitivities are also to be matched carefully, a first order should be fine? No?
And my XO point question remains: Highest I could go in this design (low placed woofer) is probably 300Hz. I have no idea how low the 165GMF would go on its own in a narrow baffle. Can someone model it for us? And if low-passed at around 200-300, would the woofers in the list fill in as high as 1k (I think that is where the 165GMF starts to rise).

[zmyrna]

troelsgravesen.dk
I was looking at this website, and it seems that when the woofer is low, you can't really cross higher than 120-140Hz. If higher, the vocals start coming from down below apparently.
I am hoping that the SV 165 GMF can go as low.

[nullspace]

Originally Posted by zmyrna

John:
What exactly is the benefit of having so many pieces in the XO?
The drivers in my list seem to have quite flat responses as they are (in the range they will be used at least).
If the sensitivities are also to be matched carefully, a first order should be fine? No?
And my XO point question remains: Highest I could go in this design (low placed woofer) is probably 300Hz. I have no idea how low the 165GMF would go on its own in a narrow baffle. Can someone model it for us? And if low-passed at around 200-300, would the woofers in the list fill in as high as 1k (I think that is where the 165GMF starts to rise).

Well, a reasonable frequency response for starters...

I would think that 200hz is a reasonable low-end cutoff for the 165 GMF on a reasonable baffle, say 24"Wx40"H.

The crossover for the Lowther/ToneTubby OB is a first-order crossover, so it certainly can be done.

You'll need more sensitivity from the woofer than you get from the widerange driver in order to get much low-end.

I highly recommend tracking down a copy of MathCad and subscribing to Martin J. King's worksheets. Invaluable for modeling.

Regards,
John

[Sjef]

I have some Tone Tubby 12" Alnico as well and use them underneath my 8" Phy-HP drivers. I use them just as a fill-in between the Phy's and my woofers from 120Hz to 300Hz. This is to fill-in the natural 300 Hz roll-off of the Phy's on my baffles. Could have used bigger baffles offcoarse but I happen to like the sound of smaller baffles more.

The Tone Tubby's are not woofers, don't expect to get any low end out of them. JvH was using some Hartley subs with them, they simply can't do without a woofer. You can get them as low as 80 Hz but that's as low as they will go.

I have also tried the Tone Tubby's in other combinations as well as full range. Don't like them fullrange, a bit too slow sounding and they have a shout, something the Phy's don't have. They can run as high as 800Hz to 1KHz I guess. Didn't have a good waveguide or horn that goes that low so couldn't try that combination but I think it can be pretty good. The combination Nulspace is using seems very promissing although I don't like horns with such a small radiation pattern here in my room it could work out good in bigger rooms.

I did try them with some low Q 6.5" PHL drivers and that worked out quite well. In this case they where used to fill-in the roll-off of the PHL's starting at 600Hz (due to small baffle and low Q) You do have to get them off the ground when you want to use them this high wich compromises the low end.

Next thing I'm gonna try is the combination with one or two Veravox 5s per side wich I bought some time ago from a forum member. Would also be crossed at around 600Hz and around 7 to 8kHz to some RAAL Ribbons I have lying around. This because I don't like the Phy-HP Raal combination because I don't like the Phy's to play higher than 3.5 a 4kHz and I really don't like the RAAL lower then 7 a 8 kHz.

But to answer your question, Yes the Tone Tubby is a decent driver, there might be betters ou there if you want to go lower but it very very difficult to find a woofer that does 30Hz to 300Hz without sounding muddy on open baffle. What started as a fullrange plan ended up in a fourway system in my case.

[InclinedPlane]

Originally Posted by Sjef

I have also tried the Tone Tubby's in other combinations as well as full range. Don't like them fullrange, a bit too slow sounding and they have a shout,

'Hemp does something you don't see in the exotic carbon-fiber, Kevlar, metals, or this-n-thatium exotics; it doesn't break up. Yes, that's right. No cone cry, no raspy breakup, no hashy grating sound at high frequencies or at high levels.'


I wish I knew who to believe.

[Sjef]

In the end you can only believe your own ears. The Tone Tubby's have there own colourtions like every speaker out there has it's colouration. Non coloured speakers simply do not exist, although there always will be people who state that theirs have zero colouration, don't believe them, it simply isn't true and it can't be true. The Tone Tubby's sound very friendly and at the same time dynamic. They do not sound like overdamped audiophile speakers but have a more alive character. Not too much like lowthers. the shout is merely from the diameter of the cone, any 12" driver used up to 5kHz or so will have it. It's up to you if you can live with that or not. Smaller drivers have less of this effect but in return they do sound, uh well, small

And about the break-up. The Tone Tubby are working in a constant break-up mode across the entire range due to their weak cone but they do not have the nasty breakup peak that stiff cones suffer from. Now most audiophiles would shiver by the mentioning of the term break-up and will seek for drivers with stiff pistonic cones wich are considered ideal by them, but on what basis ? they don't know.

And by the way, did you know that aluminium drivers like the Jordans and Bandors also work in a constant break-up mode in the entire range ? That's exactly what sets them apart from other aluminium drivers from Scan Speak, Visaton, Seas etc.