After trolling through this forum and adding my two cents' worth, I have decided to set-up my Presto 6N with Grampian cutterhead.
I need an amplifier to suit.
Has anybody done this and does anybody have any advice, tips, etc.????
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Aussie0zborn
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Cutterwoller
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What amplifier to use for the Grampian heaad
Hey there,
about a cutting amplifier for the Grampian head. I use the origianal Grampian cutter amp type R.A.7 but these were made in the 50s and are quite rare considering i have never seen another one. Gotham Audio Corporation in America made amps to go with the head but im not sure wot there like, there probs really good tho. There woz a gotham one on ebay a few weeks ago which didnt sell so it could come up again. But if your not looking for a specific tube cutter amp, I am not sure but I think just a normal Power amp might work. However on cutter amps there is equilisation which compensates for the RIAA curve when its reproduced so, i think you preamp would have to do the opposite of the RIAA curve before it goes into the power amp and i am not to sure about how you would do this, Some sort of box ting? Do not give up the grampian heads are amazing when they are set up correctly!!
Which model is your Grampian head?
Anyway I hope this helps,
Lewis, London
about a cutting amplifier for the Grampian head. I use the origianal Grampian cutter amp type R.A.7 but these were made in the 50s and are quite rare considering i have never seen another one. Gotham Audio Corporation in America made amps to go with the head but im not sure wot there like, there probs really good tho. There woz a gotham one on ebay a few weeks ago which didnt sell so it could come up again. But if your not looking for a specific tube cutter amp, I am not sure but I think just a normal Power amp might work. However on cutter amps there is equilisation which compensates for the RIAA curve when its reproduced so, i think you preamp would have to do the opposite of the RIAA curve before it goes into the power amp and i am not to sure about how you would do this, Some sort of box ting? Do not give up the grampian heads are amazing when they are set up correctly!!
Which model is your Grampian head?
Anyway I hope this helps,
Lewis, London
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cuttercollector
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using a generic power amp to cut
For any feedback head, you need to introduce the feedback coil signal OUT OF PHASE to the amplifier you are driving the head with. Amps will vary and ideally you want an amp that has little phase shift and is not prone to oscillation on its own. There are probably specs for how much feeback this cutter requires and how much power it will take. Remember, in the days of tube amps when your head was made, 50 watts was cosidered pretty high power! The level of the discs you cut and the distortion will be controlled by how well the amp and feedback loop work. You can use a mixer to introduce both the feeback coil output and the signal to the cutter amp. You could probably pre-emphasisze the program material with some sort of eq to the opposite of the RIAA playback curve. Don't eq the feedback signal with the program signal. In the older disc cutting amps, the record eq MIGHT have been part of the overall feedback loop or done seperatly. Either way will effect the curve of the recording, though I think if you did choose to eq the feedback coil loop from the cutter and leave the program input "flat", the curve would be the same as the playback RIAA curve (perhaps use a commercial magnetic phono preamp off the feeback coil?) because it effect is inverted because it's in the negative feedback loop. Be careful in your experimentation, there are many ways to blow up heads and amps!
Lewis....
I tried emailing you directly and replying to your earlier post. I am intrigued that you are starting at an early age, as I did myself. I had the Grampian D head and the Gotham Amplifier. My system was modified by Howard Holzer (HECO) in California.
I had the 6N lathe, in fact two of them. One was fitted with the Grampian C head which is identical to the D except for the feedback coils. The Gotham amp had various eq settings.
I found by using different viscosities of damping fluid for the type D head this effected the sound qualitys. I would be interested in hearing more about what you are doing with your hobby. You can contact me directly at dhersk@hutman.net
I tried emailing you directly and replying to your earlier post. I am intrigued that you are starting at an early age, as I did myself. I had the Grampian D head and the Gotham Amplifier. My system was modified by Howard Holzer (HECO) in California.
I had the 6N lathe, in fact two of them. One was fitted with the Grampian C head which is identical to the D except for the feedback coils. The Gotham amp had various eq settings.
I found by using different viscosities of damping fluid for the type D head this effected the sound qualitys. I would be interested in hearing more about what you are doing with your hobby. You can contact me directly at dhersk@hutman.net
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chris muth
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Advice needed : Setting Up Grampian with Presto 6N
Hi Aussie,
One of my best friends is Al Grundy. He has been cutting records for around 60 years and used to be the president of the Audio Engineering Society. He has a shop full of Presto, Grampian, Neumann, Scully, etc. etc. parts and amps. He can also rewind yer cutterhead and supply you with schematics and such. Whatta guy!
http://www.cutterhead.com/
One of my best friends is Al Grundy. He has been cutting records for around 60 years and used to be the president of the Audio Engineering Society. He has a shop full of Presto, Grampian, Neumann, Scully, etc. etc. parts and amps. He can also rewind yer cutterhead and supply you with schematics and such. Whatta guy!
http://www.cutterhead.com/
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Aussie0zborn
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same head but the lathe is 8DG
a part of my story....
(I didn't want to start a new topic so I posted it here)
I have Presto 8DG (the speed of the feedscrew is controlled separately with servomotor) and Grampian type D head. I hooked it up with an old Presto 90B amp.
I've recorded a song from my computer but the signal was soooo low... so I've put mixer between comp and amp. The meter on amp moved normaly when volume on the comp, mixer and amp were fully (to the end) opened. Of course I've put a quick blow fuse (630mA) between amp and head and the fuse stayed intact (so I guess I didn't use too much power). The volume on the record increased but it was completely distorted (wonder why
) and there was a lot of hum similar to electrostatic.
Then I thought the acetate was too hard. First I used normal 60W bulb but it wasn't enough... so I switched to 100W infrared one. The difference between heated and unheated silent cut was unnoticeable.
I was desperate because of the low volume and hum so I called a friend who has some more knowledge on this. He came with all the stuff (signal generator, osciloscope, etc.) and the first thing we found out was the 'ol Presto amp was the cause of the hum and electrostatic noise. I guess it's really old.
The next thing we did was using my hi-fi Yamaha receiver. The output of amp was connected directly to the head with the fuse between. The most of the hum and noise were gone (some of the noise stayed because I'm using used stylus for tests).
When we recorded the 1kHz sinus wave we noticed there is a very fine flutter distortion of the wave. I've checked if the stylus was firm enough in the shank (and it was), then I tried different speed of the feedscrew and different speed of the platter (33 and 45 rpm) but the flutter was still the same - no difference!
--> help me with this one 
When we recorded music the flutter wasn't noticeable. We drove the amp to the level when fuse glowed red on the peaks. The recorded volume was again very very low - about 30dB too low. The thread was nice (curly and shiny) all the time.
Now I don't know where to continue... of course we will have some more sessions with my friend but I'd like to have some key-words.
Some questions: Is it really necessary to use the power amp? I know it must be as linear as possible but my hi-fi Yamaha also has the "loudness" trimmer so I guess It can be approximately linear. The next thing - do I need to use preamp? I noticed some difference when using the mixer but I didn't use it (yet) with hi-fi amp. Right now I'm building a heating for stylus but I'm afraid to use it as I cut lacquer (I burned some of the thread intentionally
).
First thing I want is to get a decent volume cut. What exactly can be done here? Does the cutting angle influences the volume level? .....
So the problems I must solve for now:
- that flutter noticeable when recording sinus wave
- increase the recorded volume
Could someone help me with this? I can send the sample of the "fluttered" sinus wave if anyone wants (first I have to put it in a digital form )
Many thanx in advance!
(I didn't want to start a new topic so I posted it here)
I have Presto 8DG (the speed of the feedscrew is controlled separately with servomotor) and Grampian type D head. I hooked it up with an old Presto 90B amp.
I've recorded a song from my computer but the signal was soooo low... so I've put mixer between comp and amp. The meter on amp moved normaly when volume on the comp, mixer and amp were fully (to the end) opened. Of course I've put a quick blow fuse (630mA) between amp and head and the fuse stayed intact (so I guess I didn't use too much power). The volume on the record increased but it was completely distorted (wonder why
) and there was a lot of hum similar to electrostatic. Then I thought the acetate was too hard. First I used normal 60W bulb but it wasn't enough... so I switched to 100W infrared one. The difference between heated and unheated silent cut was unnoticeable.
I was desperate because of the low volume and hum so I called a friend who has some more knowledge on this. He came with all the stuff (signal generator, osciloscope, etc.) and the first thing we found out was the 'ol Presto amp was the cause of the hum and electrostatic noise. I guess it's really old.
The next thing we did was using my hi-fi Yamaha receiver. The output of amp was connected directly to the head with the fuse between. The most of the hum and noise were gone (some of the noise stayed because I'm using used stylus for tests).
When we recorded the 1kHz sinus wave we noticed there is a very fine flutter distortion of the wave. I've checked if the stylus was firm enough in the shank (and it was), then I tried different speed of the feedscrew and different speed of the platter (33 and 45 rpm) but the flutter was still the same - no difference!
--> help me with this one When we recorded music the flutter wasn't noticeable. We drove the amp to the level when fuse glowed red on the peaks. The recorded volume was again very very low - about 30dB too low. The thread was nice (curly and shiny) all the time.
Now I don't know where to continue... of course we will have some more sessions with my friend but I'd like to have some key-words.
Some questions: Is it really necessary to use the power amp? I know it must be as linear as possible but my hi-fi Yamaha also has the "loudness" trimmer so I guess It can be approximately linear. The next thing - do I need to use preamp? I noticed some difference when using the mixer but I didn't use it (yet) with hi-fi amp. Right now I'm building a heating for stylus but I'm afraid to use it as I cut lacquer (I burned some of the thread intentionally
).First thing I want is to get a decent volume cut. What exactly can be done here? Does the cutting angle influences the volume level? .....
So the problems I must solve for now:
- that flutter noticeable when recording sinus wave
- increase the recorded volume
Could someone help me with this? I can send the sample of the "fluttered" sinus wave if anyone wants (first I have to put it in a digital form
)Many thanx in advance!
Still nobody????
I know this is the part I suppose to find out by myself but anyway...
My biggest problem is I don't get my cuts loud enough. I've tried different cutterhead weight, cutting angle, I heated the lacquer up to 50ºC with 100W infrared bulb, I incorporated the heating for stylus but still no difference. Maybe it is the lacquer (and it's age) itself afterall.
Problem is also the amp. My Presto 90B is going to the end (it needs to be recapped) so I'm using my Yamaha receiver which is capable of 120W (so it says). It is strange that the cuts are more quiet than cuts with presto (which is 30W). Does anyone know what could be the problem?
I'm cutting without silicone fluid in the head and without feedback. Do you think this might be the issue? First I wanted to cut a decent volume, then to improve the eq curve.
Please let me know what to do!!!
I know this is the part I suppose to find out by myself but anyway...
My biggest problem is I don't get my cuts loud enough. I've tried different cutterhead weight, cutting angle, I heated the lacquer up to 50ºC with 100W infrared bulb, I incorporated the heating for stylus but still no difference. Maybe it is the lacquer (and it's age) itself afterall.
Problem is also the amp. My Presto 90B is going to the end (it needs to be recapped) so I'm using my Yamaha receiver which is capable of 120W (so it says). It is strange that the cuts are more quiet than cuts with presto (which is 30W). Does anyone know what could be the problem?
I'm cutting without silicone fluid in the head and without feedback. Do you think this might be the issue? First I wanted to cut a decent volume, then to improve the eq curve.
Please let me know what to do!!!
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cuttercollector
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- Joined: Sun Jun 11, 2006 4:49 pm
- Location: San Jose, CA
Did you say what impedance your head is?
If it is not in the 4-16 ohm range no modern direct coupled solid state amp will deliver the voltage (not current or power that is not the issue) that it needs across a load impedance in the 500-600 ohm range. You need an amp designed (typically with an output transformer with the right 600 ohm tap) to drive that.
Many people have talked in various threads about getting their heads both remagnetized and rewound for lower impedance in the range of a modern speaker.
If it is not in the 4-16 ohm range no modern direct coupled solid state amp will deliver the voltage (not current or power that is not the issue) that it needs across a load impedance in the 500-600 ohm range. You need an amp designed (typically with an output transformer with the right 600 ohm tap) to drive that.
Many people have talked in various threads about getting their heads both remagnetized and rewound for lower impedance in the range of a modern speaker.
One inexpensive option to get the head working is to use a standard 70.7V PA transformer. The 10 watt tap will exactly match an 8 ohm amp output to a 500 ohm load. You connect the transformer backwards from the normal way it was intended. That is the 8 ohm sefcondary tap goes to the output of the amp and the 70.7 volt 10 watt primary is connected to the cutter head. The only possible downside here is the low freq response of the typical PA transfomer. You will see the response below 50hz fall off. If you use an overzise transformer with more iron, say one designed for 30 watts, you would expect better performance. However, the cost will increase. Radio Shack has a cheapy one at $13.99, but is only available online. The part number is 55013095. The Atlas sound HT327 (32Watt) and HT167 look like they would work fine. These have low freq response rated at 30hz and 40hz, but are much more expensive. Hope this helps.
I bought the head from a guy in the States (I forgot his name but someone mentioned him here - he is selling all lathe stuff on eBay). He said the head was laying around and he got it from a friend who used it. About rewinding he didn't know. Also I just mounted it and started to use.
I know about the matching impedance. I triple checked that!
The datasheet says the impedance is 15 ohms at 1kHz. I measured the resistance of the coils and they are 4 ohm for main and 23 ohm for the feedback - just as datasheet says.
Maybe I should rewind it after all - this I didn't think about.
Does anyone know somebody who could do it? I know all about the US pros but I would really need someone in europe. I'd like to have the head back as soon as possible and I don't want to have any more argues with our customs (you hardly find so stupid people in the world). A while ago I contacted some italian guy who repairs neumann heads and he also know some about presto... but he had never heard about grampian.
So... I would give this head to someone in EU who knows about this.
Does anyone know this kind of person? I would appreciate it a lot!
Thanx for now... I'll post about the results when I solve these things out.
thanx!
I know about the matching impedance. I triple checked that!
The datasheet says the impedance is 15 ohms at 1kHz. I measured the resistance of the coils and they are 4 ohm for main and 23 ohm for the feedback - just as datasheet says.
Maybe I should rewind it after all - this I didn't think about.
Does anyone know somebody who could do it? I know all about the US pros but I would really need someone in europe. I'd like to have the head back as soon as possible and I don't want to have any more argues with our customs (you hardly find so stupid people in the world). A while ago I contacted some italian guy who repairs neumann heads and he also know some about presto... but he had never heard about grampian.
So... I would give this head to someone in EU who knows about this.
Does anyone know this kind of person? I would appreciate it a lot!
Thanx for now... I'll post about the results when I solve these things out.
thanx!
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Steve E.
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yeah, it would be great to know more Europe resources! I would add them to this link, too:
https://lathetrolls.com/viewtopic.php?t=3&mforum=lathetrolls
https://lathetrolls.com/viewtopic.php?t=3&mforum=lathetrolls
http://www.radiobanter.com/showpost.php?p=497150&postcount=7
You need one that has the right output watts.
You need one that has the right output watts.
Happy to learn something new.
Wanted: Stylus for Presto, Mono heads Grampian, Fairchild, Presto, Fairchild 740 lathes, Presto 8n, 8d 8dg lathes or parts or Presto or wot ever recording Amps, PM me what you have for sale.
Wanted: Stylus for Presto, Mono heads Grampian, Fairchild, Presto, Fairchild 740 lathes, Presto 8n, 8d 8dg lathes or parts or Presto or wot ever recording Amps, PM me what you have for sale.