Tone Tubby alnico hemp drivers

scorpion · « **Reply #140 on:** 24 Jul 2008, 10:54 am »

Painkiller,

Exellent, on axis I suppose. Your measurement is good evidence for the usability of ceramic TTs. They seem to be as ruler flat in midrange as the Alnicos.
The smaller the cone diameter the higher they will go and the fall off seem to be in line with Lynn Olson's observation. Very interesting !

/Erling

painkiller · « **Reply #141 on:** 24 Jul 2008, 11:00 am »

Yes, they are ruler flat, both subjectively and in measurements. The crazy thing is that I can EQ in the frequencies from 3-20kHz and it actually sounds better than my previous $3000 coffin speakers.

Now I can never go back to regular speakers.

I just have build a speaker around one of these TT drivers.

Graham Maynard · « **Reply #142 on:** 24 Jul 2008, 12:15 pm »

Hi painkiller.

From your figures there appears to be a serious sensitivity mismatch.

You are likely to need 2x Alpha in parallel per channel anyway.

To bring the TT level down you could try a 110V to 30-35V transformer.
The impedance matching will not be ideal, but it might establish whether this sort of winding ratio is appropriate.

That could then work out as three 15"ers in a vertical line with the TT between the Alphas, which might be rather impressive looking too.

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

Viridian · « **Reply #143 on:** 24 Jul 2008, 01:07 pm »

Quote from: painkiller on 23 Jul 2008, 09:22 am

So I guess the only sensible option is to get one of those Rythmik plate amps, and crank the bass volume up to the same level as the midrange. Pushing the bass drivers towards their limit.

This OB experience sure has been a bumpy ride. And it's starting to get more expensive than I wished for.

I feel your pain, but hey, I would be very interested to know how the Rythmik amp works out. I am considering one for use with my Goldwood 18" Qts of 1. I will use those as bass augmentation for the Hemptone ER8's which I still have not actually gotten. The TT factory is in the middle of a move and they are just plain too busy I guess. I don't have any xfmrs laying about and am not sure how I would implement Grahams T-bass circuit anyway. Need to look at the schem more.

painkiller · « **Reply #144 on:** 5 Aug 2008, 06:57 am »

I have to appologise for my negative impressions of the Alpha 15A. After driving them in and tailoring the frequency response, these drivers deliver deep, powerful, tight bass. Really impressive! I like them a lot. I think the Rythmik amp with the "OB shelf" would suit it very well. I'd probably need to raise the gain a little to match the Tone Tubbys though.

But me and my "wife" decided that we need a plasma screen more than a sub amp, so it'll be a while before I can order the plate amps, and a more suitable tweeter.

Meanwhile I have no problem enjoying the EQ'ed sound of the TT / 15A / Peerless XT104. It's really among the best speakers I've ever heard. I prefer it over any boxed speaker I've listened to.

scorpion · « **Reply #145 on:** 5 Aug 2008, 06:05 pm »

Pain killed !

aa

/Erling

scorpion · « **Reply #146 on:** 8 Aug 2008, 08:45 am »

Hey Painkiller,

You have exellent measurement facilities. You can analyze your setup to the smallest detail. You don't have to run buying a plate amp just because some people brag about it. And the Alphas wont go much deeper than their 41 Hz Fs which will be sufficient for 99.9 % of music. If you want them to go lower, you should look att MJK's U- and H-frames here: http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf . I will build a stereopair of the H-frames, two units each side 80 x 40 x 40 cms, going down to under 30 Hz 93 dB effeciency.

/Erling

painkiller · « **Reply #147 on:** 18 Aug 2008, 10:14 am »

I really don't believe that my earlier measurements are reliable.

Running sine sweeps It seems like the level is flat up to 2800Hz where there is a slight rise up to 3200 Hz. The driver starts rolling off heavily beyond 5000Hz (and not 3000Hz as the response measurement suggests). It's either the sensitivity of the ears at different frequencies that contribute to the apparent uneven response, or a plain measuring error.

It sounds good anyway though.

Using Graham Maynards T-bass circuit, I've managed to get quite a good SPL from the Alphas. So I've decided not to go for plate amps and active bass after all. It'll be a passive speaker, possibly with a couple extra bass drivers. I'm also eager to try the Fountek NeoCD2.0 ribbon drivers, as their SPL should match the Tone Tubbys much better than the Peerless textile domes. Exciting times. aa

fergs1 · « **Reply #148 on:** 19 Aug 2008, 10:23 am »

Greetings fellas, Erling I have readd MJK's article on flat, H and U frames and I was wondering why does the sensitivity go down with the h andd U frames. If you made a flat baffle with the same relative area would that exhibit in a loss of sensitivity. The reason I bring it up is that Ive roughed up some quick baffles ala Richard with the B200 and alpha 15 (same dims and coil) and on its own I dont have nearly enough bass, so I add bass with a pultec preamp. The whole thing is run passive and so the idea of adding wings or a H or U section for the alpha wouldnt work if the sensitivity plumets. I dont want to have a seperate amp for the bass if I can help it and so any thoughts woould be greatly appreciated.
peace and goodwill fergs

scorpion · « **Reply #149 on:** 19 Aug 2008, 03:25 pm »

Hi fergs,

I am not at home now and it will be a qouple of days before I can look at simulations.
Hope that's OK.

Cheers
/Erling

fergs1 · « **Reply #150 on:** 19 Aug 2008, 06:57 pm »

Thankyou Erling, very much appreciated
peace and goodwill fergs

Viridian · « **Reply #151 on:** 19 Aug 2008, 10:03 pm »

removed

Graham Maynard · « **Reply #152 on:** 20 Aug 2008, 09:04 am »

Quote from: fergs1 on 19 Aug 2008, 10:23 am

Greetings fellas, Erling I have readd MJK's article on flat, H and U frames and I was wondering why does the sensitivity go down with the h andd U frames.

This could depend upon the type of microphone doing the measuring, and thus would be a genuine observation which might be slightly different to our human experience.

I think it likely that sides on a baffle increase the generated pressure differential, thus reducing cone velocity, and also modifying the radiated waveform according to the proportion of dimension related pressure generation with frequency (which is what leads us to hearing the wings anyway).

The passive transformer bass circuit will lift your Alpha low bass another 6dB and yet further cut upper bass with respect to the B200 if you are using a SS or NFB type tube amplifier. You might then need less steep a crossover on the Alpha, and thus less phase shift too.

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

Rudolf · « **Reply #153 on:** 20 Aug 2008, 02:41 pm »

Quote from: fergs1 on 19 Aug 2008, 10:23 am

I was wondering why does the sensitivity go down with the h andd U frames.

H- an U-frames are a step beyond just adding wings to an open baffle. A H-frame is mass loading the driver in a symmetrical manner - raising the MMs of the system. This helps to lower Fs and reduces sensitivity. BTW: A H- or U-frame with a wider cross area will loose less sensitivity than a narrow one.
No need to talk about microphones here

Keep in mind that the reduced sensitivity does not compromise the max SPL ability - you just need more watts but gain some bass.

fergs1 · « **Reply #154 on:** 20 Aug 2008, 05:23 pm »

Greetings fellas, thanks for the replies, much needed help as I'm having real trouble getting the latest baffles past my darling wife (36 x 24 ala richard) and so the thought of a narrow baffle with wings(ala Erling) or Grahams T bass circuit and running the bass off nfb amp (I was hoping not to biamp but it justt keeps rearing its head).B y the way is a gainclone considered a ss nfb amp? One things for shure these decisions would be impossible without the help of you guys. A big thanks
peace and goodwill fergs

scorpion · « **Reply #155 on:** 21 Aug 2008, 09:33 pm »

Fergs,

My simulations say that two wings 60 cm (24") (h) x 30 cm (12") (d) 90 degrees to the main baffle would fix Alpha15 sensitivity to match the B200.
Just test with cardboard or some thicker paper and see if that is the case !

/Erling

fergs1 · « **Reply #156 on:** 22 Aug 2008, 12:06 am »

Greetings Erling, thankyou for taking the time to help me. I must ask is that assuming using the current sizes baffle 23w x 36 h and adding the suggested wings to that. If so its certainly going top make for an enormous sized baffle or am I missing something. Thanks again for your help.
peace and goodwill fergs

p.s. Have you spoken to nigel lately?

scorpion · « **Reply #157 on:** 22 Aug 2008, 12:20 am »

Fergs,

Have a look at my 'Volks-OB': http://www.audiocircle.com/index.php?topic=46951.0 its wings have exactly these measures. You can even get them more behind the baffle as yours are 23" wide.

I am afraid I never spoke to Nigel. But we had a chat in the 'Volks-OB'-thread not so long ago.

/Erling

Lynn Olson · « **Reply #158 on:** 5 Oct 2008, 08:26 pm »

Thanks for sharing your experience, painkiller. I don't know which version of the 12" TT I was measuring, it's entirely possible that the one that I borrowed didn't have the dipped-cone driver. The folks at TT were never very clear on what difference the dipping process made - and from your experience, it adds a big peak in the midrange. Sounds like the 15" Super Boy is a better all-around choice, and still has the big-diaphragm midrange magic.

Russell Dawkins · « **Reply #159 on:** 5 Oct 2008, 11:23 pm »

Welcome, Lynn!

It's a privilege having you here.