Tone Tubby alnico hemp drivers

jeffac · « **Reply #200 on:** 19 Nov 2008, 10:19 pm »

Thanks for that. Was using 660uF with no series resistor but was too low bass dominated. Have a few more NP caps on the way that will make playing about with this a bit easier. Only testing a single baffle "still" - "procrastinating ol' slow coach that I am" -

so 2 of the Alphas are still in boxes should things not work out. However, based on Posts #62 and #65 from Ric Schultz in the DIY EP CS2 clone thread, it appears that there are significant SQ improvements to be had by damping the frames of the Alpha's, and as I have a source of some freebee viscoelastic damping material, I'm about to give this a try. Based on what I heard when I fitted the Alphas to fire rearwards, baskets facing out on GM's suggestion, the frames generate s***t loads of nasty resonances. Good in concept maybe but they only lasted this way around for about a day.

cheers.. jeffac

painkiller · « **Reply #201 on:** 16 Dec 2008, 01:04 pm »

Here's an update on my ongoing project, including a tweeter recommendation.

I have now replaced the Saba tweeter with a Beyma CP380 compression driver in a 18Sound XT120 small horn. The tweeter is crossed with a 2,2uF series cap. I also added a 3,3uF and 10R parallel notch filter. The tweeter is damped with 5R in parallel. This thing plays down to 1kHz.

The sound is absolutely marvellous! The tweeter has a non metallic diaphragm and is soo smooth sounding all the way up to 18kHz. Even cymbals and violins are portrayed beautifully and relaxed. In fact, they gave me immediate chills the moment I hooked them up and started playing music. This is by far the best tweeter I have ever heard. Highly recommended!

I also connected the TT Superboy to the T-bass circuit, and added a series inductor. I just unwound the inductors until the bass drivers rolled off around 1kHz. No exact science there. The sound is much less fatiguing when the 15" drivers don't play high frequencies. The Superboy is in fact much better as a midbass driver than as a fullrange driver. Not very surprising perhaps.

The best part is that my setup doesn't need EQ any more... and I can enjoy amazingly detailed, dynamic and undistorted sound from top to bottom.

Graham Maynard · « **Reply #202 on:** 16 Dec 2008, 10:00 pm »

Hi Painkiller,

Good to hear you are running from flat input.

It takes some effort to get things balanced (drivers and circuit components), but once achieved, the reproduction is so rewarding.

Just clean sound without electrically introduced group delays, and no room pressurisation induced effects.

You must have quite a high efficiency reproducer there !

Cheers .............. Graham.

FJK · « **Reply #203 on:** 6 Jan 2009, 08:01 pm »

I am also thinking of buying a pair of the 12' alnico TT's to put on open baffles (have not decided on which tweeters or woofers yet).

My current speakers are Bastanis Prometheus and would ideally have the same 3-way type set up. With the Prometheus there is only a high pass cap for the tweeter and a single resistor across the positive and negative terminals on the treated wideband eminence to flatten the impedance load.

So I'm wondering if I could get away with using this same type of no-crossover arrangement (not sure I need the resistor as I would order the 16 ohm version) or is the midrange peaking that bad. According to Nullspace in his email to me it is there and he built a crossover to address it (I forgot to ask which version TT he has).

I'm thinking of special ordering their original H1 speaker as I understand it is the darkest of the ones offered. Should I worry that it might be too dark?

painkiller · « **Reply #204 on:** 6 Jan 2009, 08:37 pm »

No, you can not use these drivers crossoverless in my opinion. One thing is the midrange peak. Another issue is the beaming. But the worst problem is probably how distorted these kind of large drivers sound above 1kHz. The drivers are great as midranges, but don't go crossoverless. Let a good hornloaded 2" compression driver do the work above 1kHz. That's my opinion.

I wouldn't worry about the untreated version sounding "dark". They may sound dark as guitar speakers, but you're not using them to play guitar. It just means that they are less peaky.

I may come off a little negative here, but I actually do think these drivers are great. I'm just starting to get tired of the "large wideband driver" concept.

nullspace · « **Reply #205 on:** 6 Jan 2009, 09:29 pm »

Quote from: FJK on 6 Jan 2009, 08:01 pm

I am also thinking of buying a pair of the 12' alnico TT's to put on open baffles (have not decided on which tweeters or woofers yet).

...

So I'm wondering if I could get away with using this same type of no-crossover arrangement (not sure I need the resistor as I would order the 16 ohm version) or is the midrange peaking that bad. According to Nullspace in his email to me it is there and he built a crossover to address it (I forgot to ask which version TT he has).

Hi Frank,

I have the standard issue H1Es.

Here's a sneak peek at what I'm using for a crossover currently; it looks more complicated than it really is. I've been meaning to start a thread/ update my website with the details, but haven't pulled together all the bits and pieces....

Drivers are 2xToneTubby 12" AlNiCo on open baffle and Beyma CP380M w/ 1000hz 50deg conical horn from Acoustic Horn Co.

Regards,
John

FJK · « **Reply #206 on:** 6 Jan 2009, 09:35 pm »

That's a little depressing.

Although, Painkiller did you not buy a treated brighter TT and wonder if that is why you had these problems.

I know the Bastanis I have does have some sort of violin varnish added to it that allows it to sound pretty good up to 10khz. I was hoping to hopefully be able to get up to around the same numbers with the TT (but without any treatment should I go with the H1).

I read on Lynn's site that they treated the internal basket with felt and this helped tame a portion of the peakiness. I did the same with my Bastanis a few months ago when I wanted to lower the upper midrange a touch. Also I saw the felt roller pics on the TT and wonder how much this helped.

Another trick that I could borrow from the Bastanis would be to use round chair leg felt pads. On my Prometheus they are glued to the cone in a circular fashion near the middle.

FJK · « **Reply #207 on:** 6 Jan 2009, 09:40 pm »

John I did not see your post as I was putting up mine. The "that's depressing" refers to Nullspace's suggestion warning against crossoverless.

Thank you for putting up the schematic. I will have to decide if I want to go that route.

BTW why did you use two 12 inchers?

nullspace · « **Reply #208 on:** 6 Jan 2009, 09:56 pm »

On a narrow baffle, 18", the drivers start rolling off pretty high. So, I have a second driver as a helper or ".5". Buys me another octave to an octave and a half on the low end. I have a quartet of AE OB15 to cover sub-120hz, though -- the ToneTubbys don't go much lower on a small baffle.

It should go without saying, but the crossover schematic is practically useless unless you're going to duplicate my setup precisely, and even then, I won't guarantee you'll like the results... It should be viewed more as an example of what one barely-skilled amateur was able to cobble together and get non-terrible results with.

Regards,
John

FJK · « **Reply #209 on:** 6 Jan 2009, 10:58 pm »

I was hoping at least 200hz with a single driver.

I'm trying to get an idea of the tone of the drivers. Lynn mentioned they sound very natural. John you mentioned you were using the Fertin fied coils and wonder how your Tone Tubby creation compares tone wise to them.

panomaniac · « **Reply #210 on:** 6 Jan 2009, 10:58 pm »

Quote from: painkiller on 6 Jan 2009, 08:37 pm

I'm just starting to get tired of the "large wideband driver" concept.

Awww... come on. Why? It's fun and easy. Sounds good too.
(says the guy who runs big 2 ways crossed at 1KHz)

painkiller · « **Reply #211 on:** 7 Jan 2009, 07:57 am »

Nice setup you've got going there Nullspace. aa How do you like the Beyma tweeters? I really love those, but I would like a 2" compression driver also for a lower crossover frequency. How did you calculate your filter?

I did have the double treated cones, yes. That may have been part of the problem. I guess I'll never know. I don't think the cone treatment gave any extended frequency response though. Just a more uneven response. The drivers have quite a stiff surround, and low Xmax, so you won't get much bass out of them. I'd recommend them as a pure midrange driver 200Hz-1kHz or something like that.

Panomaniac: Yes, It's fun, cheap and easy. It's better than a lot of commercial speakers and dynamics are impressive. But it's the distortion I'm getting tired of. Large drivers at high frequencies... It's not meant to be. IMNSHO

nullspace · « **Reply #212 on:** 7 Jan 2009, 12:41 pm »

I like the Beyma tweeters quite a bit. They do very little wrong and seem to blend well tonally with the ToneTubbys.

A 2" driver would be nice, but I would think you would need a horn that will enable you to hold directivity much lower in order to crossover lower, and horns like that get very large very quickly. If I had the space, I'd love to try the Altec/GPA 1.4" phenolic drivers down to 300hz, but the horn would have to be something like 2 feet in diameter.

The short version is that I came up with the filter by doing a number of measurements for both drivers, both on- and off-axis, simulating the network in SpeakerWorkshop, then tweaking the component values by listening. It only took me eight months or so...

Regards,
John

nullspace · « **Reply #213 on:** 7 Jan 2009, 06:26 pm »

Okay, I've made some updates. Here's the long version, and the recap is that I finally have made some real progress on my 2xToneTubby 12" AlNiCo plus Beyma CP380M w/ horn project. Crossover, posted above, is ~1.2khz for the upper TT12 and Beyma drivers, and the lower TT12 is low-passed at 270hz. I'm sure there's a ton of stuff I missed when putting together the crossover, but all in all it's not too bad and I'm very happy with the sound. Very dynamic, nice tonality, and not at all forward or shouty in and of themselves (crappy recordings are another thing, however).

I still need to work on the (sub)woofers. As expected, the mains rolloff around 100-120hz. I have something in place now, but it's not worth discussing. I have a quartet of OB15 from the nice fellows at AE, and I'm looking forward to getting baffles made and the active filtering built up. I already have the boards back from ExpressPCB and components have arrived from Mouser.

Fire away.

Regards,
John

painkiller · « **Reply #214 on:** 8 Jan 2009, 07:56 am »

Wow! That looks really great! I would guess it sounds better than most commercial hifi gear. It is, however, a big advantage having some measuring equipment when making speakers with non-standard drivers. I'm thinking of a combo with M-audio Mobilepre soundcard and a calibrated Behringer microphone. That would be a great help when experimenting with different drivers.

You could try the T-bass circuit on the lower bass-driver, and gain quite some output below 100Hz. It's very effective. But you would be pushing the Xmax, and you need a stable SS amp. Side braces on the lower driver would also help preventing early rolloff.

What horn is that on the Beyma? It looks conical.

nullspace · « **Reply #215 on:** 8 Jan 2009, 12:19 pm »

Thanks for the compliment. I try to be open-minded about the divide between those who insist that measurements are the be all and end all and others who assert that the greatest measuring device of all are those two things stuck to the sides of ones head, but I can't imagine trying to make real progress without taking reputable, repeatable measurements.

The horn is from Bill Woods at Acoustic Horn Co. It's a 50degree conical, his AH!1000. I heard his stuff at the VTV show in NJ, and liked them quite a bit. He also does the heavy-lifting for OswaldsMillAudio, which was one of my favorite rooms at this past year's RMAF.

Regards,
John

painkiller · « **Reply #216 on:** 8 Jan 2009, 02:18 pm »

I've never heard of the Acoustical Horn Company until now. Thanks for the link! Those 300-horns look awesome! I'm in the market for some big horns. aa I've been looking at some vintage JBL 2360 horns with 800x800mm horn mouth. Those beasts are sick. (In a good way)

Do you know how the radiation pattern is with these conical horns? Any polar plots available?

nullspace · « **Reply #217 on:** 8 Jan 2009, 04:00 pm »

If I had room, I'd absolutely get a pair of the AH!300. Here they are at RMAF, with some old school RCA drivers.

The radiation pattern is quite narrow, 50 or 60deg, depending on the horn. You can ask Bill if he has any 'official' polar maps. Here are my 1/24 octave smoothed measurements for the Beyma driver. That's 0 to 35deg, in 5deg increments -- 40 and 45deg were nonsensical, so I left them out. They maintain directivity to almost 2k, then start widening from there. Works to my advantage in this instance.

Regards,
John

painkiller · « **Reply #218 on:** 8 Jan 2009, 07:12 pm »

Those are some nice measurements. Dispersion looks promising. Somewhat uneven on axis, but a bit off axis they're really great! It also looks like the ideal crossover frequency is about 2 x Fc? 50 degrees is a little too narrow for a small listening room, in my opinion. More appropriate for pro audio. Still very interesting horns. I think I'll send a mail to Bill Woods with some questions.

BrassEar · « **Reply #219 on:** 8 Jan 2009, 10:37 pm »

Quote from: jeffac on 19 Nov 2008, 10:19 pm

based on Posts #62 and #65 from Ric Schultz in the DIY EP CS2 clone thread, it appears that there are significant SQ improvements to be had by damping the frames of the Alpha's, and as I have a source of some freebee viscoelastic damping material, I'm about to give this a try. Based on what I heard when I fitted the Alphas to fire rearwards, baskets facing out on GM's suggestion, the frames generate s***t loads of nasty resonances. Good in concept maybe but they only lasted this way around for about a day.

FYI, I used FATMAT on the Alpha baskets (as well as the rear of the DDS WG) and this did make things much cleaner. Less blur. A cheap and effective tweak.