ortofon ds522 feedback coil

Post: # 15760Unread post d Wed Jul 06, 2011 4:52 am

Hey

anyone familiar on rewinding feedback for ds522? Need to know the wire diameter and other specs... mine just died and cannot find the reason.

any info is appreciated.

Post: # 15761Unread post **Serif** Wed Jul 06, 2011 10:24 am

Ask Torben at etec.dk or Len Horrowitz at hrsrecords.com.

Might also find info from host of:

http://tubeguru.hu/audio_tube_amplifier_SE/ortofon_cutting_latthe_files/Media/

He shows a Fonofilm Industri A/S D. S. 522 head in various positions and a cool vintage Ortofon manual, but a lot of the text is obscured by the head resting on the book, many pictures are upside down, and most is about the Lyrec lathe used often with this head!

Good luck,
Andrew

Post: # 15763Unread post **Serif** Wed Jul 06, 2011 10:28 am

P.S., Flo's site says: DS 522 mono, feedback. . simpel and great sounding cutterhead. with feedback.8 ohm drive coil,200 mA max . constant current 65 ohm feedback, Fres=1500 Hz

Andrew

Post: # 15772Unread post **dubcutter89** Wed Jul 06, 2011 3:29 pm

Hmm, looks like you have bad luck with this head...

...would like to know how you killed the fb coil

for rewinding, a 0,04mm wire should work. maybe smaller would be better, but then you it will get really really hard to do...

Lukas

Post: # 15774Unread post d Wed Jul 06, 2011 5:20 pm

Thanks Serif and Lukas for response.

Yesterday I took out the coil. yes it is realy small...

now finishing on building template for it. today got wire 0.03 mm. Should be ok I think.

Just a minute ago I splited coil into two parts to count how many turns do I need to do, but seems like i am out of luck with this. The wire diameter is too small for my microsocope...

maybe there is other way to calculate how much wire or turns do i need for this coil?

and yes, I am really having a bad luck with this head. it came with broken stylus holder and even before it was broken and modified to hold 320 stylus. I wasn't informed before buying it. well i didn't asked. as it stated it was seller refurbished and in working condition.

i still cannot find the cause, why FB coil was killed. I did one test cut and it was OK. Then tried to cut once more and it was it.

Post: # 15792Unread post d Thu Jul 07, 2011 4:18 pm

now i really need some help...

how is that kind of small coils winded without a frame that holds them? any tips on this?

Post: # 15810Unread post **dubcutter89** Fri Jul 08, 2011 4:49 am

Hmm,

I guess you could make a little frame (maybe 2 flat washers?),
dip them in releasing agent, and then wind the coil into/onto them,
wait until glue/laquer is hardened, disassemble the construction and
glue the coil onto the armature...

I have a second cutter around which needs the same treatment,
but I haven't been in the mood for doing this yet...

BTW: Have you got a working amp right now?

Lukas

Post: # 15811Unread post **dubcutter89** Fri Jul 08, 2011 4:53 am

I'm not sure if this is how they were made, but I think this could work.
And of course you will need a good microscope, and a little aid which holds
your forms, copper-wire etc...

Lukas

Post: # 15819Unread post d Fri Jul 08, 2011 4:27 pm

Hey Lukas,

thanks for suggestions. i was just thinking about that. most tools i have. today tried to wind but need to find better washers with exact 2mm holes.

what is releasing agent? vaseline maybe or smth better?

now i just poured a drop of laquer on coil but it only sticked on that spot. will try figure out more. somehow they are done. trying to search the web for correct procedure....

best regards

Post: # 15910Unread post **subkontrabob** Thu Jul 14, 2011 8:04 pm

@Lukas: The guy who owns the machine that I have cut on owns one DS 522 and two 501's. He has quite a stash of stylii, some worn (at least it says so on the box). I could ask him if he may want to spare a few for experiments.

The DS522 is at Flo's repair shop at the moment (nicked stylus holder as well..... these are delicate..... bad engineering.....)

Did you open up the cutterhead? The feedback coil is inside the actual head, just below the stylus holder IIRC. Flo sent me some nice photos....

Post: # 15924Unread post **dubcutter89** Fri Jul 15, 2011 10:58 am

I could ask him if he may want to spare a few for experiments.

That would be great! Have been searching for some so long, without succes...

I also got two Ortofon Monos. One DS522, and the other looks the same,
but has no type engraved. Both still have the original stylus holder,
and I just don't want to change it -- keep it original state!

Lukas

Post: # 15925Unread post **flozki** Fri Jul 15, 2011 1:43 pm

DS522 feedbackcoils are on its way....
2-3 weeks from now.i sent out the order.
finest backed coils. i hope to get the price wednesday.
the thing is that i need to make at least 100 pcs. but we would never use 100 pcs. so they are maybe a little more expensive. $40-50 or maybe $100 and you get 5 coils. bu let me wait for the price.
by the way i received the caruso preamp prints. so if some of the DS522 users want to give a try. empty board is $40 plus shipping (but it goes in a letter.)

f.

Post: # 15933Unread post d Fri Jul 15, 2011 3:59 pm

@subkontrabob

of course I had opened the cutter. It seams very simple... insides are not so dificult to understand. But haven't try to take out magnet pole plates near drive coil to see what can be seen under them... heh

tried to make the coil in brutal way, got some results but still have to make it good, so will try one more or two times if ok then will use them or wait when the flo gets good ones.

Maybe someone has the picture of how does this head looks totally disassembled? want to see how stylus to take off vibrating member ...

@ flo and others

i will ask here not to mess other places here. as i see on caruso preamp diagram there is 22khz lopass filter. I understand what it does, but a question goes like if it is really needed in all preamps for cutters? maybe it is mostly needed for killing undesired high frequencies that gives nothing but bad sound?

Post: # 15968Unread post **dubcutter89** Mon Jul 18, 2011 3:49 pm

But haven't try to take out magnet pole plates near drive coil to see what can be seen under them... heh

I wouldn't take out the magnet... Take out the complete armature.
I made a simpel tool for it - A small screwdriver with a little slot in the middle of the blade

Underneath the long screw, which comes from top of the head, there is the small nut which holds the armatur.
You can loose it with your custom-cutterhead-tool - et voila - take out the whole thing

@ f.k.

Would be interested in fb-coils! I still got the wire you've sent me years ago waiting for a wind...

Post: # 15971Unread post d Tue Jul 19, 2011 1:07 am

Hey Lukas,

thanks a lot, you cleared the day. so it means that the armature has the fixture to stay in place.

i have took the head to a friend, he has most of tools for fixing little things. He will weld the 320 stylus holder to the armature so i dont have to play with epoxy in the future.

Post: # 16483Unread post **subkontrabob** Thu Sep 22, 2011 6:39 am

Last saturday I visited Flo. He had replaced the broken armature of a 522. We measured the response of the head from the feedback coil, and made some nice test cuts with it, through Flos Caruso preamp prototype using feedback

.

Flo mentioned this in his Caruso PCB thread:
https://lathetrolls.com/viewtopic.php?t=2765&mforum=lathetrolls

He's such a nice and professional guy, good work with reasonable pricing.

Why not make a communal effort with all ds501/522/compatible ortofon mono head owners and fund manufacturing of a bunch of fb coils? Even if you don't need any at the moment, it might be a good idea to have some spares ready in case of emergency. I would gladly invest 50 €

Post: # 16484Unread post d Thu Sep 22, 2011 6:57 am

Hey

this is a very nive effort. I would add some too. Depends on the price tag.

I have discussed this with Flo and it was quite high. So I am into making some by myself. and I am almost there. Just do not have time for this at the moment.

Will write here any results.