This afternoon I meet a guy from my neighborhood that build stereo guitar pickups , and other modding in musical instruments , he build him own winding machine , with an arduino and other things in that way.
He encourage me for unmount completely an old unusable 500 ohm 1C head , the man goes fast in 10 minutes he have the two little coils unmounted and ready for rewinding , know comes the questions.
one pole to one coil , the other pole to the other coil , and the coils are the same jointed wire , but the two coils are winded in the same direction ? or are inverted like in a humbucker ?
He gonna check the most similar wire that he can find , and rewind to 15 ohms , and clean and rework some screws.
Someone knows how is this head winded ?
Best Regards
Mani
Rewinding a Presto 1C
Moderators: piaptk, tragwag, Steve E., Aussie0zborn
Rewinding a Presto 1C
Very Busy days , some cutting works at least , soon online again
We must promote the use and abuse of vinyl records.
We must promote the use and abuse of vinyl records.
Hi,
I re-wound my 1C and 1D for 8 ohms using 29 ga. wire. The total wire length is more important than the number of turns. I used 8 feet of wire which resulted in a coil resistance of about .84 ohms (for one coil). This will fill the bobin. Because the head is push-pull, the coils are connected in series, but with the fields in opposition.
Originally, my head was wound at 500 ohms and I measured 120 feet of 37 ga. wire when I dissasembled it.
Mark
I re-wound my 1C and 1D for 8 ohms using 29 ga. wire. The total wire length is more important than the number of turns. I used 8 feet of wire which resulted in a coil resistance of about .84 ohms (for one coil). This will fill the bobin. Because the head is push-pull, the coils are connected in series, but with the fields in opposition.
Originally, my head was wound at 500 ohms and I measured 120 feet of 37 ga. wire when I dissasembled it.
Mark
Wow , very concrete answer , thats is exactly the trick. We gonna try it on this afternoon , I will post the results , but is difficul , I never heard a presto cut
before , in that way is difficult to say if goes right or not.
Thanks Mark.
Cheers
before , in that way is difficult to say if goes right or not.
Thanks Mark.
Cheers
Very Busy days , some cutting works at least , soon online again
We must promote the use and abuse of vinyl records.
We must promote the use and abuse of vinyl records.
Hi,
Remember to add a series resistor to the head. This is used to set the 500hz RIAA turnover. Above 500hz, the head is cosntant velocity, so if you use the series resistor, you will only need to add boost at the 2125hz turnover and a small amount of boost below 50 hz. After re-winding my head, I found 2 ohms to be about right, however if you may need to adjust this a bit.
You should check the rubber damping material to make sure its has not become hard. If so, you have two options. Leave it out and correct the response with EQ or replace. Withotu damping the head has a resonance in the 4-8Khz range. Watch out for the for the small machine screws as they can easily strip the mating threads in the round brass clamp.
I would also check that the aramture is centered between the pole peices, clear of any debris, and gapped to about .005". You can use the set screws on the side of the head to re-balance the aramture.
Good luck and let us know how you do.
Mark
Remember to add a series resistor to the head. This is used to set the 500hz RIAA turnover. Above 500hz, the head is cosntant velocity, so if you use the series resistor, you will only need to add boost at the 2125hz turnover and a small amount of boost below 50 hz. After re-winding my head, I found 2 ohms to be about right, however if you may need to adjust this a bit.
You should check the rubber damping material to make sure its has not become hard. If so, you have two options. Leave it out and correct the response with EQ or replace. Withotu damping the head has a resonance in the 4-8Khz range. Watch out for the for the small machine screws as they can easily strip the mating threads in the round brass clamp.
I would also check that the aramture is centered between the pole peices, clear of any debris, and gapped to about .005". You can use the set screws on the side of the head to re-balance the aramture.
Good luck and let us know how you do.
Mark
that is an excellent question, actually.aaron wrote:If the damping was removed, would that improve the high frequency response?
but as mark said, it will add resonance..
I have 2 non feedback mono heads, and I'm trying to figure out why one of them is better at high frequencies, and the other is better with bass.
The RCA head does highs very well, even though it's a simpler design.
generally its for reproduction.. but i like to play wif it sometimes.. 
Hi,
If you over damp the head, then high frequency response will sufffer (too much of a good thing). There were heads back in the day that ran without damping and used that peak as part of the high freq EQ. I saw this described in the Morrison book. Universal was one such head (see US patent 2198080). In this design, the resonance was tuned much like a guitar or piano string by adjusting the spring tension. The idea was to make use of the rising response as part of the EQ. It also eliminated changing damping due to age or temperature.
Mark
If you over damp the head, then high frequency response will sufffer (too much of a good thing). There were heads back in the day that ran without damping and used that peak as part of the high freq EQ. I saw this described in the Morrison book. Universal was one such head (see US patent 2198080). In this design, the resonance was tuned much like a guitar or piano string by adjusting the spring tension. The idea was to make use of the rising response as part of the EQ. It also eliminated changing damping due to age or temperature.
Mark
Hi Steve,
That sounds about what I've seen on my heads when I first got them. This may indicate that the damping material has lost its flexibility. Also check to make sure that the 4 small brass screws used to attach the damping material are coupling the damping to the armature. Along with that, make sure the round clamp is not loose (its threaded and IIRC, soldered to the armature). You might try using a short shank version of the stylus. THe downside is that you will get less cutting level. If you have an older stylus that still works, you can just cut the end off to shorten it. Annother possible problem is the tensioning of the aramture balancing springs. Normally, they are used to center the armature. But over time, I've found that the baseline stiffness has dropped. So, you may need to increase the tension a bit. Be careful with this adjustment. Finally, these heads are affected by the cutting medium. I've seen different results on the bench (no mechanical load) vs. cutting a lacquer. While heating the stylus does not really affect frequency response, it can lower the mechanical impedance the the head sees. This can have a significant effect on the response.
Mark
Mark
That sounds about what I've seen on my heads when I first got them. This may indicate that the damping material has lost its flexibility. Also check to make sure that the 4 small brass screws used to attach the damping material are coupling the damping to the armature. Along with that, make sure the round clamp is not loose (its threaded and IIRC, soldered to the armature). You might try using a short shank version of the stylus. THe downside is that you will get less cutting level. If you have an older stylus that still works, you can just cut the end off to shorten it. Annother possible problem is the tensioning of the aramture balancing springs. Normally, they are used to center the armature. But over time, I've found that the baseline stiffness has dropped. So, you may need to increase the tension a bit. Be careful with this adjustment. Finally, these heads are affected by the cutting medium. I've seen different results on the bench (no mechanical load) vs. cutting a lacquer. While heating the stylus does not really affect frequency response, it can lower the mechanical impedance the the head sees. This can have a significant effect on the response.
Mark
Mark