Restoring the cabinet, and re-foaming the electrostatic tweeters. Telefunken Dacapo 9 part 8.

No restoration is complete without doing the cabinet work. This, I must admit, has never been my favourite job, but it must be done.
Here I describe and show the various tasks necessary, and come to a sticky point: the electrostatic tweeters.
These tweeters are notorious for failing, and a simple test can be used to confirm this. The repair is also something that can be quite interesting for anyone needing to try this themselves, so enjoy the video.

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TimeStamps
00:00 Restoring the cabinet, and re-foaming the electrostatic tweeters. Telefunken Dacapo 9 part 8.
00:11 Introduction.
02:21 The cabinet, before and after.
08:36 Testing the electrostatic tweeters.
10:52 Tweeter repair.
31:34 Conclusion.

#tuberadios #antiqueradio #radiorestoration

______HUNDREDS OF OTHER VIDEOS TO CHOOSE FROM_____
DIY TEST GEAR: The title says it all:

RESTORATION BUILDING BLOCKS: A series of videos showing detailed steps used the restoration process of tube equipment:

HowTo's: Various videos on some simple techniques and projects:

See also playlists on some other completed restoration projects.

PHILIPS BX750A:

TELEFUNKEN OPUS 2114:

SABA UW-175-Z 3D:

GRUNDIG 1070:

SCHAUB-LORENZ GOLDY 58 type 3020:

BUSH VHF64:

GRUNDIG 3060A:

TELEFUNKEN OPERETTE 8:

GRAETZ SUPER 171W:

LOEWE-OPTA MAGNET 3737W:

BRAUN ATELIER 3:

LOEWE-OPTA TRUXA STEREO 4741W:

GRAETZ COMEDIA 616:

SABA FREIBURG W2:

GRAETZ MUSICA 4R417:

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CAPACITOR LEAKAGE TESTER:

[bamboozled]

With you and mr Tipton, it’s been tweeter repair week ! Coincidence? 🤔

[howardhiggins]

I would bet that the consistency and hardness of the original foam gasket is carefully chosen.
Thanks for sharing this series.

[chrisclark]

Hi Manuel. I really enjoyed this. You certainly did an excellent job of repairing those speakers, and may I say a very well explained and detailed description of how they work and rectifying the problem. You have also achieved a superb result with the cabinet. Can't wait to see the end result. Cheers Chris.

[geofham]

Hi, awesome skills all round with the electronics, narratives and video presentations. I learn so much from you, many thanks. From Nr Liverpool UK.

[douro]

Zenith also put electrostatic tweeters in some of their radios. I have a series-string set with one. The tweeter is actually connected directly across the plate and cathode of the 35C5 output tube. I believe mine actually works.

[Rush-gzsx]

I'm a long distance lorry driver and know absolutely nothing about valve radios but I just love the look and sound of the mid 50s to early 60s German sets and so far have managed to collect 4 of them. A Graetz Melodia, a Blaupunkt Lugano, a Loewe Opta Apollo and an Imperial.
I'm actually pretty good at restoring the cases and plating the brass but that's the extent of my radio knowledge.

When I park up at night I watch a couple of your videos and although the subject matter goes over my head a little you explain what you're doing with so much simple clarity I dont get bored or lost.

I find myself googling what specific parts (such as capacitors and rectifiers) do and only get a rudimentary answer sometimes explained to technically.

I'd love you to do a complete idiots guide to a basic valve radio. One with just the back removed where you point to the power cord coming in and explain the path the current takes, through what components and what action those components actually do. Basically a real idiots guide. I'm sure there are many people like me fascinated and hungry to know more.

Great videos very well presented thank you.

[waynethompson]

Well done, though I must admit I am still a bit in the dark in understanding the ElectroStatic Speakers. When you said they are working properly, and put the microphone near them, they sounded terrible. I am sure there is just something that I don't understand at the moment, but even if you have the regular speaker playing, the sound I heard from the ElectroStatic Speakers would come out more like an irritating noise than an enhancement to the speaker.

[BKGoldDetecting]

Good timing, I have some tweeters that aren’t working on my Schaub Lorenz. Nice to see some of the non electrical details. I had one back cover that was really faded and I found that gently rubbing on some clear dubbin added a natural shine and also bought out the detail on the lettering well.

[DavidTipton]

I have to say Manuel, the case looks fantastic and it's great that you got your speakers to work, a bit of a different design to mine and I can see how your speakers work. I thought you did the selenium rectifier on this one or was it another? I'll have to wait and see. Thanks Manuel 👍

[Swingguido]

These superb electrostatic speakers were designed in 1955 for the Telefunken model "Gavotte", in cooperation with Isophon, the famous german producer of loudspeakers.(Source: "Funktechnik" magazine, 1955)

[edwardhannigan]

Wow, nice job..! Tweeters seem to be a pain..😀 Thanks for sharing..Ed..UK..😀

[rádiosantigos]

Muito legal. Eu assisti o vídeo do Tipton e fui referenciado para o teu canal. Bem feito, bem editado e muito didático. Espero que o Tipton consiga solucionar os tweeters da eletrola dele após esta demonstração. Thanks. Alvaro.

[jamesmdeluca]

Greetings:
Good foam substitute; 3M foam mounting tape; about 1/8" thick, 5/8" wide, peelable sticky straps top and bottom.. Trim to size including crosswise sections; peel only front facing side. May be useful for Bluetooth board mounting, too.
I heard you mention wire color variation; any chance the left/right are out of phase?
The rear metal perforated plate must have electrical contact to one of the wires. Perhaps that was the source of the intermittent contact.

[DAVIDGREGORYKERR]

They are like the ESL Electrostatic speakers which have three terminals one common which the audio transformer connects to and the other two plus and negative.

[erikdenhouter]

The function of the foam seems to be to press the middle frame onto the plastic sheet and the gold (colored ?) sheet, to assure good contact with the copper grid.
I would have tried felt, because I think they only used foam because it is easy and cheap, but as we now know often not durable.

[Stelios.Posantzis]

23:56 An electrostatic that works at 200V is some kind of novelty! I wonder how efficient they are. I'm quite amazed by how simple their construction is. Definitely made for large volume, cheap production. I wish there's more information on them on the internet. I wonder why this design was never adopted for larger drivers. It has a lot going for it, it seems.
So I guess the foam was just a spacer. I wonder if some other kind of material could be used instead that would not deteriorate.

[nigelbrockwell]

That is the first time I've seen an electrostatic tweeter, something new to learn about. Is the frequency response of these very similar to piezo tweeters?

[DAVIDGREGORYKERR]

A W007 Round Bridge Rectifier should work

[DerekHerbst]

Nice work. That thin film is not Mica. It's Mylar, with one side being conductive. It's normally the side that touches the"frame". The foam presses the frame onto the conductive layer of the Mylar sheet. You can make a replacement sheet using space blanket. Use a multimeter to find the conductive layer. The "grid" is there to provide the opposite electric field.

[clasicradiolover]

These and the magic eye were totally new to me. The biggest thing about working on these old radios is that I was told it's easy to get shocked by a capacitor. How to ensure they are discharged I don't know.