WTB Lathe-Seeking Advice + Knowledge [+ crucial digressions]

[ajroach42]

I run a small record store.

We are looking to buy a lathe to occasionally cut records in store.

I am a novice in these regards. I've read a lot of posts here, and the consensus seems to be that I need to be prepared to spend a lot of money, tinker with the bits constantly, and accept that it's not going to sound perfect.

It is my understanding that, once they have ascertained these facts, most people are scared off. I am not scared. I am honestly excited as hell.

Initially, we want to do something simple. We expect the resulting records to be little more than a novelty.

Please help me make sure that I understand what I am getting in to.

It is my understanding that, for this, I would want a presto or Rek-O-kut lathe. It is also my understanding that the resulting sound quality will be laughable at best, and that I should expect to spend between $250-1500 on a working unit (or enough non working units to Frankenstein a working unit together.)

If I am correct in this understanding, I would very much like to discuss the various merits of each of these systems (and know of any that are currently for sale in Georgia!!!)

If all goes well, eventually we would like to move to a true Hi-Fi system. It is my understanding that a Sculley lathe would probably be our best option. It is also my understanding that finding one for sale will be virtually impossible, and that I should plan to construct the finished product out of bobs and bits, and spend upward of $20k.

If I have all of this right, it will likely be a long time before we can move in that direction (5+ years). In spite of that, I'd still like to gather as much information as possible in the intervening time.


So, wonderful forum dwellers, if you would be so kind:

What are some good entry level lathes?

What is a fair price for these machines?

Do you know of one currently for sale in the Atlanta area?

What are some caveats and Gotchas that I should beware of?

Any other information that you'd like to volunteer?

[Angus McCarthy]

Welcome, AJ! Glad to see you have a firm grasp of the possible pitfalls and money traps associated with this calling.

As to Presto vs Rek-o-kut, I can personally only speak for the merits of some of the Presto models. I've worked with three so far: K-style units and a 6N. The K models are solidly built, very portable, and when in top condition are capable of cutting a perfectly serviceable disc. The only major drawback is that since they are a swing-arm fixed-pitch type mechanism, you are restricted to one thread-per-inch count (unless you are lucky enough to snag a k-10 or 11) and do not have the ability to cut lead-in or lead-out grooves. K's have been going on eBay for anywhere from $300-$900 depending on condition and model.

The 6N is pretty much the standard "semi-pro" lathe you'll still see out there. They are very versatile. Assuming you can get ahold of multiple screws you can cut a wide range of LPI's. The manual crank lets you cut lead-in and lead-out sections, as well as band breaks at any point during a cut. Having a 16" platter means that not only can you properly play back 14" or 16" radio transcription discs if you find them, but you can -for all intents and purposes- cut a 14" master for pressing, if you so desire. On the upside, there are a lot of parts floating around out there for 6Ns. Conversely, these parts are ruthlessly hunted down by current and prospective 6N owners. They do pop up on eBay now and then and have been seen to go for upwards of $2000, depending on completeness and overall condition. A lot of 6Ns were orphaned from their portable cases and studio plinths, so you will likely have to construct a new frame for one.

An issue that has started to crop up, it seems, is the big old beefy motors finally giving up the ghost after 50 years or more of disuse. There are replacements out there, but they require some re-working of the electrics. (Standards do change over the course of 70 years!)

There have been examples of Trolls successfully mounting relatively high-fidelity stereo heads on modified 6N carriages, so you may not have to go whole hog on a Scully to get better sound than the stock 5C or 1D heads.

[ajroach42]

Well that was about the most useful and informative post I could hope for.

I'll put some more research in to the presto models. A fully working 6N sounds like it would be the ideal beast, but it's a bit more than I was hoping to spend to start out on. I think that I will make that the dream machine (and spend the next 3-5 years looking for one.)

The other prestos, as you've described them, also sound fantastic.

I'm not sure how they compare to the rek-o-kuts, so if someone else want's to chime in I'd appreciate it. At this point though, it looks like I'll be digging around for a working presto or two.

[tragwag]

for ease of fixing and maintaining, you can't beat the prestos.
Rek o Cut feedscrews come up once in a while, but there are Presto 6N feedscrews all the time, and even a new batch currently in production by Steve E. the forum owner. thats just the tip of the iceberg as far as maintenance as well.

if you have any interest in hearing an 'impressed' (or embossed) lathe cut record from my 6N system, let me know.

[ajroach42]

So it sounds like a presto is definitely what I'm after.

Could you give me a bit more information about the difference between "impressed" and "cut" records in process and quality?

Can the prestos be used to cut, or jut to impress?

Also, with regards to cutting heads, I would prefer a mono head with high frequency response to a stereo head. I assume I could increase the frequency response of a poor head by half speed mastering, is that possible with the presto units?

Could I get some more information about cutting heads?

[opcode66]

Cutting is as it sounds. You cut into the blank and thereby remove a small amount of it. What is removed from the blank is the inverse of the groove. Small and hair like. Goes by Chip in USA and Swarf oversees. Cutting will give you the highest fidelity audio on disc with little to no background noise when using a fresh lacquer, a good cutting styli with burnishing facets and heat.

Impressing removes no material from the blank. You are literally just making an impression on the surface of the disc. You are displacing material. Impressing is lower quality. Background noise is always present. Burnishing facets are relatively irrelevant. Heat on both the tip and blank itself helps to increase fidelity and decrease bg noise.

Presto's can do either: cut or impress.

Mono heads are generally capped at 10K with respect to frequency response. Nothing short of completely re-engineering with give it a wider frequency response. The only thing that half speed cutting does is increase the accuracy of the representation of high frequencies in a groove. Half speed recording will not in any way increase your frequency response.

Buy old books on disc recording whenever and wherever you can. That is where you'll learn more about cutterheads. Do searches here. Get documentation on old heads. Get the AES Anthology on disc recording.

[ajroach42]

Thanks for the help!

It sounds like, with a cutting head, I'd need a way to remove the cut plastic from the disc. I remember reading something about vacuum systems, so I assume that this is where those come in to play. Is that right? [Man, there were a lot of pronouns in those sentences.]


Are there any specific books you'd recommend, or should I just pick up whatever I can find? Anything that is still in print?

Sorry for all the questions, I'm just trying to wrap my head around all this information.


And thanks again for all the help. This has been a wonderful experience.

[markrob]

Cutting is as it sounds. You cut into the blank and thereby remove a small amount of it. What is removed from the blank is the inverse of the groove. Small and hair like. Goes by Chip in USA and Swarf oversees. Cutting will give you the highest fidelity audio on disc with little to no background noise when using a fresh lacquer, a good cutting styli with burnishing facets and heat.

Impressing removes no material from the blank. You are literally just making an impression on the surface of the disc. You are displacing material. Impressing is lower quality. Background noise is always present. Burnishing facets are relatively irrelevant. Heat on both the tip and blank itself helps to increase fidelity and decrease bg noise.

Presto's can do either: cut or impress.

Mono heads are generally capped at 10K with respect to frequency response. Nothing short of completely re-engineering with give it a wider frequency response. The only thing that half speed cutting does is increase the accuracy of the representation of high frequencies in a groove. Half speed recording will not in any way increase your frequency response.

Buy old books on disc recording whenever and wherever you can. That is where you'll learn more about cutterheads. Do searches here. Get documentation on old heads. Get the AES Anthology on disc recording.

Some incorrect info in this post.

There are several mono heads that top 10Khz response. The Grampians, Neumanns, and Ortophons come to mind. Even the Presto 1D can be extended beyond 10Khz with little effort.

The comment about half speed mastering is also incorrect. If you have a head that can cut to 10Khz at standard speed, then you extend its ability to 20 Khz at half speed. Just basic common sense. In fact, back in the early days of CD4 disk cutting, JVC used half speed mastering to allow the cutting of the FM 30 Khz carrier and sidebands using the heads available at that time. The issue with half speed mastering is at the low frequencies. The signal chain driving the head needs to have extended low frequency response (down below 10Hz). This was difficult for tape machines back in the day, but easy for a digital system.

Mark

[ajroach42]

Mark,

Both of those additions seem to be corroborated by what I am reading. I appreciate the input.

I will look in to the cutting heads you mentioned. I've got an ortofon cartridge on my turntable right now, and it was a pricey piece of kit, but it's the best sound I've ever had out of a stereo. I imagine that the ortofon cutting head would rival that (in fidelity and price. )

Do you think eBay/Craigslist are my best options for finding gear and literature? Or is there a secret resource hidden somewhere that I would being it from?

[Steve E.]

I can say with certainty that, given the right EQ curve, my Presto 1D cutting head will cut close to flat, at the start of the LP side, up to 14K or above.

[Steve E.]

Here's a good place to start:

http://lathetrolls.pbworks.com/w/page/22959575/The%20Secret%20Society%20of%20Lathe%20Trolls

[ajroach42]

I can say with certainty that, given the right EQ curve, my Presto 1D cutting head will cut close to flat, at the start of the LP side, up to 14K or above.

That's good to know. Thanks.

Here's a good place to start:

http://lathetrolls.pbworks.com/w/page/22959575/The%20Secret%20Society%20of%20Lathe%20Trolls

Awesome! I'll read through all of this. Thanks!

[opcode66]

Yea, ok, guess I wasn't really thinking before I answered. I don't cut with Mono heads. I remember reading that most only went up to 10K. Also, I don't do half speed cutting. So, upon reflection, I understand that what I said was not entirely correct. Certainly what I said about more accurate representation of highs is correct.

However, something that no one has pointed out is that when you do half speed cutting you loose the entire lower octive of frequencies. So, if your music is bass heavy, it won't be after cutting half speed...

[Steve E.]

We all have incomplete knowledge, even those on the board who know a lot. I'm all for getting it out there as best we can and then correcting each other. It's all good.

[opcode66]

We all have incomplete knowledge, even those on the board who know a lot. I'm all for getting it out there as best we can and then correcting each other. It's all good.

Yes precisely. I certainly don't know everything. And, I'm human and make dumb mistakes like everyone else. But, I always try to post what I can. Even if it is just for community revision. This site continues to grow and evolve into a fantastical resource only through the continued efforts of those who give the site life. Anyone who posts that is...

[Stevie342000]

Something else (I think this has not been mentioned in this thread at least), when half speed mastering your IRIAA turnover frequency would need to change, suppose you can do that digitally but what about if you old school and use equalisers active or otherwise?

[markrob]

Something else (I think this has not been mentioned in this thread at least), when half speed mastering your IRIAA turnover frequency would need to change, suppose you can do that digitally but what about if you old school and use equalisers active or otherwise?

Then you have to do it the old school way as well and either modify the fixed values of your IRIAA network (e.g. double all cap values) or adjust your EQ. If you are planning to use a tape machine at half speed, the playback EQ needs to be modified or compensated for with external EQ.

To Todd's comment about the low frequency issues involved; the head itself is not an issue. A moving coil head has flat amplitude response down to DC (that is required for many depth control systems to operate). The problem is making sure that the signal chain feeding the head is up to the task. If you want flat response down to 20hz you probably want to have your signal chain flat to well below 10hz. The other issue to deal with is that the feedback system is velocity based, so the closed loop velocity response is not flat below a certain point. There may also be some ringing and overshoot in the response near the low frequency cutoff. This would require some special EQ to compensate for these effects. I understand that some pros don't care for the cutting results obtained by going half speed. I suspect that it is the result of dealing with some of the side effects (no free lunch).

For DIY'ers like myself, it really is a good way to extend performance.

Mark

[opcode66]

I have a bulletin form Neumann where they discourage half speed cutting for two reasons. It doesn't really have a tremendously noticeable effect. And, you loose the lower octave. Straight from the horses mouth.

[markrob]

Hi,

I think that may be more an issue of using a tape machine (which was the only way back then). It would take some special modification to the machine to push the bandwidth down below 10hz. Did the paper you are making reference to give any technical details? Perhaps their point is that given the great performance of the SX cutting system at 1X, the hassle of making all of the mods to work at 1/2X is not really worth it. When CD4 was developed, they needed to make use of half speed or the current state of the art would have been a problem. One other advantage to half speed is that you can cut hotter levels at the high frequencies. For example; if your system can cut 10cm/sec at 10Khz as a max value, that translates to 20cm/sec at 20Khz on playback. That may be a moot point as you can already cut a recording that can't be played back without problems with an SX system. But, this implies that you could cut hot disk with less power and stress on the head at half speed.

Do you agree with my statement that the head is not the limiting factor here?

Mark

[powerstrip]

I have a bulletin form Neumann where they discourage half speed cutting for two reasons. It doesn't really have a tremendously noticeable effect. And, you loose the lower octave. Straight from the horses mouth.

This is good info. I guess this whole 180 gram virgin vinyl thing is a little over-rated.

Except, from a lot of the DIY crowd that is into cutting x-rays, embossing plastic, etc,

It's generally said that cutting half-speed when using experimental materials can produce better results, out of the fact that you are dragging the cutting stylus through the surface a little more gracefully. It treats uneven and sloppy discs with more care, and does produce better results in "less desirable" material. I have tried it myself and have achieved better results with x-rays.