Advice needed for using Grampian type-c cutting head

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vinyl_retentive
Posts: 6
Joined: Sun Jul 27, 2008 5:10 pm

Advice needed for using Grampian type-c cutting head

Post: # 10509Unread post vinyl_retentive
Fri Sep 10, 2010 4:27 pm

Hello everyone,

I am a record collecting enthusiasts and a record cutting hobbyist. Currently have a Presto 1-c 15-ohm cutting head mounted on a Rek o Kut M-5 powered by a Rek o Kut 50 watt Imperial amp. I have been making good cuts for years with that set up, but I want to upgrade the quality of my cuts.

I recently purchased a Grampian type-c 16-ohm feedback cutting head and plan to mount it on my current lathe. But as for powering the cutter head, this is where I require assistance. I do not know anything about the Grampian type-c except it is suppose to produce a louder signal.

I require advice on:
~ Amp selection for the Grampian and where I can procure the correct amp
~ Schematics or other information on the Grampian type-c
~ Any anecdotal information on cutting with the type-c and connecting it to the amp would be much appreciated

Thank you in advance for any information you provide.

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markrob
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Joined: Wed Nov 28, 2007 1:14 am
Location: Philadelphia Area

Post: # 10527Unread post markrob
Sat Sep 11, 2010 4:41 pm

Hi,

If you PM me with your email, I can send you documentation on Grampian heads. I don't have the type C doc's but all of them are very similar. I also have a copy of Flo's preamp that has the RIAA and feedback summing.

Here is some info that might be of help. The heads are not really true motional feedback types. The feedback works mostly at low frequenices and can improve distortion and perfomance at the low end. Unlike the Presto heads, no series resisitor is needed. The head has flat response vs. recorded velocity. So, you need to apply the full inverse RIAA curve to get the proper recording characterstics. You can run the head without using any feedback and it will work well. You can drive it with most any modern amp the can provide 50 Watts peak. 1.26 watts of drive will produce 5.5 cm/sec velocity at 1Khz. The head uses Dow Corning 200 silcone oil (200-500cst) as damping fluid.



Hope this helps.

Mark

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greybeard
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Post: # 10540Unread post greybeard
Sun Sep 12, 2010 1:50 pm

Hi,

motorino is one of the users of this head who regularly posts here. I have a reference that is good if you want to study the various considerations that went into the design of the head, which was originally a BBC design. It is:
H. Davies: "The Design of a High-Fidelity Disc Recording
Equipment", Jour. I.E.E. Vol. 94, Part III, July 1947, pp. 275-295
The article is 20 pages!!

Kind regards, ...

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motorino
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Location: Aragón, ZGZ
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Post: # 10541Unread post motorino
Sun Sep 12, 2010 4:38 pm

Hello

I believe the type C dont have feedback..

Use the search button, Grampian, you have a lot of links, pics, etc

Cheers
Marcos

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cymbalism
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Location: omaha.nebraska
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Post: # 10542Unread post cymbalism
Sun Sep 12, 2010 5:28 pm

Correct, I have a type c and it is not a feedback head. Instead it reads magnetic on it.
all the best!
- tommie 'plan 9' emmi
poly-cut lathe cuts / cymbalism recordings

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