Soundbox / reproducer DIY corrugated aluminium diaphragm test

[@pitombaroxa]

What a coincidence, my friend. I used this same technique to make a diaphragm. I made the plaster molds and compressed the thin sheets of aluminum. Exactly the way you did it. Somehow our thoughts meet. Congratulations.

[@mrrgstuff]

That's good to know! I think I saw some pictures on the Talking Machine forum of molds made out of clay, so I thought 3D printed ones would work well too. I made a matching pair, but just squeezing the aluminium between them didn't work well, and I ended up burnishing the metal against the mold by hand. Thanks 👍 😀

[@janderogee]

Wow, interesting experiment here. The difference between the flat aluminum membrane and a corrugated aluminum membrane is amazing. Thanks for showing these insights in your experiments.

[@mrrgstuff]

Previous to this test, the best had probably been the mica, though other materials faired reasonably well. I can see though why corrugated aluminium replaced mica as it performs very well too, is cheaper and has great scope for tweaking. Something I have not experimented with yet is the number and size of the corrugations. Thanks 👍😀

[@dynamizer2]

The study of your self-made sound box is very interesting. I also have HMV's 145 and 193 and a good 3D printer. I want to do that research too.

[@mrrgstuff]

Glad you liked the videos. It is a fascinating subject and I would be very interested in seeing and hearing one that you build. If you have any questions then I will try to help. Thanks 😃👍

[@AllMy78s]

Well I'd say the Mica and corrugated are too close to call, but your listening to them in real time... I think that improvements in the corrugated would give better results, what the improvements are not sure, but certainly have come a long way since the early experiments... Well done...

[@mrrgstuff]

To be honest I was more disappointed with the corrugated one in real life, though when listening to the sound on the video I have to admit it does actually sound pretty good! I did feel the mica was slightly better, but where as the mica cannot be adjusted really in any way, there is indeed scope to try other sorts of corrugations on the aluminium one which should result in better performance. It may be though that for older acoustic records, mica or polystyrene works better 🤔. Thanks 😀 👍

[@nickball69]

great improvement! The corrugated is very much louder. The deep circle in the aluminium foil is still used in the modern electric - membrane. The way you produce the membrane is great. I still suggest you to improove your armcontact. If you reduce the surface contact and model it in a circle way you will make sound it even better. I think you could make the needle arm longer till the center of the membrane, so you could remoove the black rectangle, having a better lever and a direct vibrating point on the membrane. Sorry for maccaroni english and God save your ears

[@mrrgstuff]

Thanks 😀 👍. I think the next version will probably have a thin flat triangle shaped needle bar as this will be stiffer than the wire version, but also have the small contact point like you mention. You may find this video interesting too: kzbin.info/www/bejne/npeyXoiip51qrac

[@rocketaroo]

The aluminium benefited alot from corrugations. The mica has better tone, but slightly more distortion. So close to 1000 subs!

[@mrrgstuff]

Yes, the corrugations were much more effective than I thought they would be. For this one off, the corrugated aluminium diaphragm was much cheaper than the mica one, and I wonder if that was the case fir manufacturers back in the day 🤔 Yes, so close to 1000. I have something very special planned for that occasion. Its on the workbench now ... 😀. Thanks 😀 👍

[@Timothycan]

Yes, I'd agree the mica is the best, but there is little difference between that and the corrugated one. I remember previously that there was also little difference between mica and the plastic one made from a CD case, so maybe if someone wanted to easily replace a diaphragm, the CD case would be the way to go! It is a good demonstration as to why the metal diaphragms had the corrugations, though.

[@mrrgstuff]

Yes, I would say that if mica is not available then a CD case is a fair substitute. I don't think the corrugated aluminium one is going to perform much better (though I have not done a direct comparison of the two), and isn't any easier to make. Its also going to look wrong in any soundbox designed for mica. I did see a HMV No.4 on ebay a few weeks back that somebody had upgraded to a corrugated aluminium diaphragm though. Thanks 😀 👍

[@NippersLounge]

I agree, the mica does sound the best.

[@mrrgstuff]

Thanks 😀 👍. I think with a bit more experimenting the corrugated aluminium one can be improved, but by how much, I don't know.

[@juslitor]

i managed to resurrect an old rusty Czechoslovakian reproducer with a torn out and missing coupling screw by simply using hot melt glue to fasten the needle arm to the diaphragm. Compared to a pot metal HMV no.4 the sound quality is very similar, trumpets are harsher but pianoes sounds bettter on the checz. Which to me is pretty neat, considering the sound is carried over hot melt glue.

[@mrrgstuff]

That's very good going! I have had some success with super glue on my home made soundboxes. Have you seen this soundbox restoration I did? kzbin.info/www/bejne/f5ymdHxui9ucqc0 Thanks 😀 👍

[@GrandadIsAnOldMan]

Fast forward and no sound for the assembly so we don't hear the screams 😁👍 well that's how I do it anyway.

[@mrrgstuff]

It was a lot more fiddly to fit than expected and in the end I had to do the central screw 3 times before it was satisfactory. Was going to cut out most of it, but at least on fast forward you can see what a faff it was! 😉. Worked out OK in the end though. Thanks 😀 👍

[@davidk6271]

Corrugated one for me. Terrific work. You should be pleased. Well done. I wonder if more corrugations would make a difference , or joining the sound bar to the diaphragm in more than one place as per a 5b? You probably deserve a rest now!

[@mrrgstuff]

Thanks 😀 👍. Yes, it turned out well in the end and the corrugations really helped, which I wasn't really sure would be the case. I may revisit this, but although I have plenty more videos on the way, many of them gramophone related, I am going to be drawing this round of testing to a close as it relies on the current positions of my 162s which will change for other reasons

[@YeshuaGod22]

Seems like the corrugations benefited the treble, but the lowest notes seemed somewhat clearer through the flat one. I find that very pertinent to my research. Thanks!

[@mrrgstuff]

I hadn't noticed that particularly, but yes the frequency response will be different. The flat one sounds very muffled to me and there is a fair amount of surface noise. Previously in another video I tested it against a flat steel one and a flat copper one and the aluminium sounded the worse. Glad it was of help to you. Thanks 😀 👍

[@tiga4180]

I'm struggling with mica versus corrugated aluminium, might be down to personal preference, which could vary between records. Despite flat aluminium sounding poor, I hear a mellowness & improved bass, at the sacrifice of treble. I'm coming to the idea that a stiff but light central area, with a highly flexible periphery is the way to go, which the HMV 5A & 5B ended up with! Must have been a good idea, I've seen similar design in quality moving coil microphones, like the Shure SM58, tho' that uses plastic rather than aluminium. No maker seems to have tried copper in gramophones, but I've met corrugated copper in an Edison phonograph. I was unable to distinguish its performance from mica.

[@mrrgstuff]

Yes the mica and corrugated aluminium seem fairly comparable. At the time of doing the tests I thought the mica was still a little better, however its not clear on the video and opinions have been mixed! 😉. Having said all that, the corrugated aluminium does perform better than I expected it to. It is interesting that the flat aluminium does well in the bass department. I didn't notice it myself, but at least one other commenter mentioned it also. I don't have an effective way of corrugating copper, so no plans for that, but something more like the 5A/5B or a composite diaphragm may yet happen. I also would like to improve my test facilities so I am not reliant on the camcorder mic and the location of the gramophone/camera bracket. Fixing that should make it much easier to do tests too. Thanks 😀 👍

[@tiga4180]

@@mrrgstuff The gut feeling with mica (plus a little added science) is that a tiny stiff but lightweight area at the centre vibrates really fast for the treble, but as the flexibility & weight gradually increases toward the outer areas, lower & lower notes are favoured. The HMV 101 seems to perform well due to its larger diameter, wonder if they found the optimum diameter, or if an even larger one would do better. Suppose it would be hard to find mica with a larger diameter than the 101.

[@mrrgstuff]

I think I have seen mica on ebay which is bigger (about 65mm). I think size tests might be more easily done using polystyrene as this performs in a similar way to mica but is much easier to work with. Thanks 😀 👍

[@deepak-ug3hx]

I have used speaker spider with centre made of plastic sheet

[@mrrgstuff]

That's good idea! I have also tried various plastic sheet: kzbin.info/www/bejne/jqKknX2MpbNmkK8si=orHQa1k9WrvNEYo5 Thanks 😀 👍

[@GramophonicReevolution]

Another great video shoot out. For me the mica just wins over the corrugated one but it's very close and personal preference really. More tweaks and the corrugated will be triumphant I expect. It does sound as though the sound is getting held at the soundbox instead of moving freely on it's way, too much resistance? That could be down to mic positioning? Is the sound we are hearing coming from next to the soundbox or closer to the horn exit? Cheers Paul

[@mrrgstuff]

Thanks 😀 👍. The sound in these videos is being captured by the camcorder, so its from the position the video is shot from. I don't have this setup anymore and am in the process of building something new. That will take the sound directly from the front of the horn. The corrugated aluminium did work surprisingly well, considering the sheet aluminium was so poor. The corrugated diaphragm was also fairly easy to make, and much cheaper than a mica one, so probably worth trying to refine in the future. I do hope to get back to DIY soundboxes, but there will be some other videos first, many of them gramophone related though 😀

[@SKPhonographs2025]

I seriously need to catch up on all of my youtube 78 RPM record stuff! I've been too busy over on my clock channel and those guys for too long! 1:52 Going on those types of forums is something I wish I knew about sooner when getting into this hobby. As for what I think sounds the best, I think the corrugated aluminum would be the way to go.

[@mrrgstuff]

Yes, the forums are helpful, I only found this one via a video by "Nipper's Lounge". There is a very active one on Facebook too. I thinks clocks and gramophones go well together and I have been enjoying your clock videos also, though looking forward to seeing more of the Colombia. Thanks 😀 👍

[@Mrpurple75]

The corrugated one is better in my opinion and that may be why most manufacturers switched to them. It is definitely closer to the mica one. Maybe if more corrugations could be put in it but not as deep? I don’t know, probably doesn’t matter.

[@mrrgstuff]

Yes, the centre is certainly more rigid. Probably could have got more corrugations in it, but I decided not to be too ambitious when designing the 3D print! 😉. Certainly something to consider if I revisit this 🤔. Thanks 😀 👍

[@TuxedoRonny]

I wonder what it would sound like with the diaphragm from a stethoscope? I'm not sure exactly what they're made of off the top of my head. Great videos, though! I love experimenting with these machines.

[@mrrgstuff]

Interesting point. Never occurred to me, but I have just googled it and apparently they are made of thin fibreglass, maybe with a rubber edge. They certainly seem to fit in like gramophone ones, with a round ring gasket. Certainly would be worth trying. I don't know what the diameter would be so the soundbox body might have to be changed and of course a hole would need to be drilled in the middle. Thanks 😀 👍

[@henkgloudemans8886]

Thank you my friend !!!!!! Greetin gs from Henk !!!!!!

[@mrrgstuff]

Thanks for viewing 😀 👍

[@terrycard6775]

Enjoying your channel. Very interesting.

[@mrrgstuff]

Thanks 😀 👍. Much appreciated. I have lots more gramophone related stuff coming up. Just need to decide how far down the phonograph route I go first ... 🤔

[@0michelleki020]

how do i make a diaphragm punch or what it's called without a 3D printer?

[@mrrgstuff]

Some people have used rings of modelling clay or plasticine. You only really need one side, and you can form the diaphragm over the clay and burnish it to shape.

[@0michelleki020]

@@mrrgstuff i see, thanks for the answer

[@Mrpurple75]

Have a design I’ve been working with. I’ll let you know

[@mrrgstuff]

Sounds great! Looking forward to hearing more. Thanks 😀 👍