Have some cutting questions / looking for some help.

[JohnnyF]

Hello All,

I got my Rek-o-Kut unit (m-12, R-8A amp) up and running this weekend, did a few tests and now have a few questions, hopefully those of you with more experience can help shed some light on whats happening.

I started by cutting on plastic plates, as I figured I couldnt ruin too many things this way. After cutting about a dozen plates and no apparent changes in quality I moved onto CDs, and ended up with about the same quality as the plates.

This is what I'm experiencing:

The grooves seem really tight - to the point that they might cross on occasion, no scope so I cant be certain. The feed screw in the unit is etched with 192 OI. In my research I've haven't seen a 192, just up to 144 then 216.

I have no idea what volume I should be cutting at. The microphone knob goes all the way to 10, but I've been keeping it around 4-5. I've been feeding the microphone input with my iPod, also keeping it low, no more than 1/3 volume.

If I turn the volume up on either the microphone (to 6) or ipod (to 50%) the cutter head begins to rattle - I can faintly hear the track, but mostly the head rattles and sounds like a blown speaker.

On playback, I do get the track, but it's quiet, skips, or gets stuck in 1 groove (almost like a lock groove). I also get many snaps, crackles, and pops. I'm aware that most of this is surface noise, as it is still there when I cut with no track or volume.

What are anyones thoughts?

I'm thinking the head is shot and it should go to Gib in the next couple of weeks.

If I'm adjusting the tracks for cutting in Audacity or Amadeus Pro is there something specific I should be doing?

Thanks for any and all help.

[opcode66]

You should hear the track through the head. That is normal. If the head weren't making noise that would be a problem. The power amplifier drives a coil in the head that pushes a piston that the cutting stylus connects to. That is how the sound is physically transcribed to disc. So, hearing the head is a good thing!

Most people integrate VU meters into the line going from the amp to the cutterhead so you can see how much signal you are giving the head. That way you know how to adjust the iPod volume/Mic volume according to the specific material you are trying to cut. Also, you can insure you are not giving the head too much power that will blow it. Adding fuses to the line is also recommended to insure you don't blow your head.

Since you say the track is skipping on playback i'm thinking you aren't cutting very deep. Too shallow of a groove will promote skipping of the playback tonearm.

192 Lines per inch is a fine pitch. On a 12" a@33 RPM 192 LPI you can get up to 18 minutes of audio at moderate volume according to one of my old charts. I cut loud dance music somewhere around 250 lines per inch and get something like 8-9 minutes at +2VU @ 45 RPM on 12". That is at the extreme end. If i bring the volume down and increase the lines per inch past 300 I can get about 25 minutes of audio @ 33 on a 12". So, I wouldn't worry about how tight the grooves appear. Under a scope, they look more spread out.

Yes, plastic has a fair amount of background noise. That is the nature of the beast. You can reduce is simply by using a 100W bulb. Just go find a desk lamp and put a 100W bulb in it and point it at the surface of the disc. I use a heat gun to tell when the surface is at the right temp to start cutting. That softens up the plastic and it gives less resistance to being cut and therefore cleaner groove walls and less background noise.

Yes, there are several things that you should do to process your audio. JayDC probably can give you more specific guidance on how to clean up your audio proper for cutting on an older mono cutter. But, it goes something like this. DeEsser set minimally to avoid excessive sustained highs that can blow your cutterhead, Low Pass filter at 10Khz, High Pass filter at 20 hz, EQ, Final Volume adjustment and then to the cutterhead.

Ask more questions. That's what the community board is here for!

Take Care,

opcode66

[JayDC]

yes desser, no high pass.. the older cutters go higher w/o it.. I actually turn the highs up past 8K to force the head to limit mechanically.. I run 100w solid state amp into a presto 1-C @ 15ohms, and need more power, lol..

On opti's vms, i dun tink he can do it this way w/o encountering a huge repair bill.. Stereo cutting is a completely different game.. and I never even got a chance to try it yet..

I know enough about the mono non feedback head, that if I actually killed it, I could fix it.. unless ofc, the tension rod snaps, or the spring is fuct.. never hurt my head no matter how hard i try... old stuff is just built better i guess..

now that being said, I wouldn't go and try to kill your cutter yet.. not till your more experienced.. Right now treat it like it's super fragile, and learn..

They will always try to tell you it'll never sound good.. and using that old amp, they are probably right. If you know the impedance, you might find a nice modern power amp that will work.. 160watts@16ohms will kick serious ass if your head is 15ohms, and you know how to use everything..

it IS possible to cut a great record w/ the old mono stuff.. it'll just take some time to figure out.. using a frequency analyzer to look at the cut after you cut it is pretty win.. help you see why its sounding the way it does, and then you know a little more on how to try to correct it..

takes forever to get the cutter angle correct too.. once you find the sweet spot, it gets easier to readjust after you move it to put a new stylus in..

rig up a fuse, stylus heating, and a vacuum too, if you don't already have it.. search the forum to figure this out.. searching the forum, and reading from the start and working you way towards today will deffo add some knowledge to your pallet..

[JohnnyF]

Thank you both for all the suggestions.

I already need a VU meter as the one on the front of the amp isnt working. I'll get that one replaced, and perhaps an inline backup going this week.

I also have lights, just didnt use then since I was cutting on such soft material(s) the first day.

I'll work with the depth adjustment - I wish this damn thing had some type of instruction manual, either with it or available on the internet. I've found a few things, but nothing too complete.

The 192 LPI seemed odd to me because it wasnt listed in any of the Reko-Kut ads that I can find. Good to know the time I can expect with a moderate volume.

One thing I did notice was inconsistent areas in the groove. It would look something like this:

________---------_______
________---------_______

Thin, then about double wide and offset a bit, then thin again. Is this because I'm cutting too soft, without enough depth, and on not great materials? I noticed it was almost eliminated when I went to the CDs.

Thanks again.

[piaptk]

It is changing depth when it gets wider. Picnic plates do that because they don't lie perfectly flat. The stylus kind of lifts the plastic up as it goes around, then it slumps and lifts back up again. One of the problems with picnic plates. You got lucky with that 192. Generally I've seen really low lpi screws on suitcase cutters, like 92-112. You can cut a decent volume record at 192 and fit some time on it.

Thank you both for all the
One thing I did notice was inconsistent areas in the groove. It would look something like this:

________---------_______
________---------_______

Thin, then about double wide and offset a bit, then thin again. Is this because I'm cutting too soft, without enough depth, and on not great materials? I noticed it was almost eliminated when I went to the CDs.

Thanks again.

[JayDC]

i don't tink running a line signal tru a mic input will yield a good result..

over modulation will yield crossed grooves, you need to turn it down, lol..

[opcode66]

That's why VU meters are suggested. So he can see where his levels are.

[JayDC]

derp.. I know.. but if you put the vu on the line your going to get a false reading coz mic pre's add something like +10db.. he needs to bypass the mic preamp, coz it will only add distortion..

[JohnnyF]

So I guess I'll begin considering and looking for an amp to replace the original one.

Since the groove width issues appear to be a plate vs cd issue, I guess I'll stick with cds for the time being - they're certainly cheap enough.

There are still plenty of knobs and screws I havent played with yet on this cutter, i.e depth adjustment - not having any type of manual makes it bit difficult to figure out what is what - but I should be able to with a bit of experimentation.

[opcode66]

derp.. I know.. but if you put the vu on the line your going to get a false reading coz mic pre's add something like +10db.. he needs to bypass the mic preamp, coz it will only add distortion..

Haven't you said you have a meter tapped on the line between your amp and your cutterhead? This would give a reading of the level after amplification and after the built in mic preamp. I wasn't suggesting to put the meter in-between the line input and the mic preamp.

[JohnnyF]

derp.. I know.. but if you put the vu on the line your going to get a false reading coz mic pre's add something like +10db.. he needs to bypass the mic preamp, coz it will only add distortion..

Haven't you said you have a meter tapped on the line between your amp and your cutterhead? This would give a reading of the level after amplification and after the built in mic preamp. I wasn't suggesting to put the meter in-between the line input and the mic preamp.

I was planning on adding a meter after the amp and before the cutter. Seems like the most reasonable spot for the meter as it'll read the signal going into the head.

Speaking of amps, any recommendations in terms of what to get or avoid?

[piaptk]

Jut make sure you get the right amplifier output impedance... Your head probably needs a 500ohm.