Is there a good reason not to cut 78 lps?
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- Jesus H Chrysler
- Posts: 190
- Joined: Sun Nov 26, 2006 12:03 am
- Location: Asheville, NC
Is there a good reason not to cut 78 lps?
I just got a 78 rpm Seeburg home library jukebox and my 78 collection is lacking, so I wanna cut some new records for it. It holds 100 10 or 12" discs. I know on older lathes where the carriage is coupled to the platter, the play time is limited by the speed, but that's not the case on a VR, so is there any reason I shouldn't cut a 15 minute or more 78 rpm side other than stylus wear?
Re: Is there a good reason not to cut 78 lps?
Hi,
78 rpm records have a much wider 'coarse' groove than that of an LP or 45 rpm single's 'micro-groove'.
Your Seeburg will be fitted with a coarse groove stylus which is around 2.5-3 mil tip diameter. Whereas your VR has a cutting stylus designed for micro groove, which is around 1 mil.
In other words, your Seeburg will struggle to track the grooves of the records cut by your VR correctly (if at all).
If you don't intend to put any real 78s on your Seeburg and only want to stick to the records you cut on your VR, then I suggest you replace the styli in the Blackhead cartridge with ones designed for 45 rpm records. These can still be bought from various places... in the US, I suggest here: http://www.needles4jukeboxes.com/seeburg_needles.htm
Don't forget to cut you records in mono!
As an aside, 78 rpm records were originally made out of a semi-natural material called Shellac. The maximum playing time was established by the maximum groove LPI that you can cut into Shellac before the wide coarse grooves begin to deform and collapse in upon themselves. Usually around 120 LPI.
78 rpm records have a much wider 'coarse' groove than that of an LP or 45 rpm single's 'micro-groove'.
Your Seeburg will be fitted with a coarse groove stylus which is around 2.5-3 mil tip diameter. Whereas your VR has a cutting stylus designed for micro groove, which is around 1 mil.
In other words, your Seeburg will struggle to track the grooves of the records cut by your VR correctly (if at all).
If you don't intend to put any real 78s on your Seeburg and only want to stick to the records you cut on your VR, then I suggest you replace the styli in the Blackhead cartridge with ones designed for 45 rpm records. These can still be bought from various places... in the US, I suggest here: http://www.needles4jukeboxes.com/seeburg_needles.htm
Don't forget to cut you records in mono!
As an aside, 78 rpm records were originally made out of a semi-natural material called Shellac. The maximum playing time was established by the maximum groove LPI that you can cut into Shellac before the wide coarse grooves begin to deform and collapse in upon themselves. Usually around 120 LPI.
Re: Is there a good reason not to cut 78 lps?
Also, some 78 jukes need an eccentric runout groove to activate the auto-changer mechanism
Re: Is there a good reason not to cut 78 lps?
True enough, but not many. All the Golden Age boxes from the mid-30s onward that I've had experience with don't need it to trip the cancel relay.
Certainly the mechanism in the Seeburg Library Unit doesn't as it's the exact same as the M100A which I own

It has trip 'sensors' for both eccentric and non-eccentric lock grooves so the best of both worlds!
Re: Is there a good reason not to cut 78 lps?
Hi,
Correct me if I'm wrong, but I think you can cut an acceptable 78 era groove with a microgroove stylus as long as you cut deep enough such that the groove width is wide enough for the 3 mil tip playback stylus to ride at the proper depth. The bottom of the groove will have a sharper profile and be deeper as compared with a period cutting stylus, but that shouldn't matter. As was stated, you will need to run at 96-120 Lpi to avoid overcuts. I assume you are not trying to cut a lacquer disc for playback, but rather plastic blank. I would expect the mech would have trouble with a thin lacquer disc and given how heavy these machines track, might not last too long. Also, a lacquer disc might not have enough coating to allow you to cut deep enough to achieve the desired groove width without hitting the aluminum base.
Mark
Correct me if I'm wrong, but I think you can cut an acceptable 78 era groove with a microgroove stylus as long as you cut deep enough such that the groove width is wide enough for the 3 mil tip playback stylus to ride at the proper depth. The bottom of the groove will have a sharper profile and be deeper as compared with a period cutting stylus, but that shouldn't matter. As was stated, you will need to run at 96-120 Lpi to avoid overcuts. I assume you are not trying to cut a lacquer disc for playback, but rather plastic blank. I would expect the mech would have trouble with a thin lacquer disc and given how heavy these machines track, might not last too long. Also, a lacquer disc might not have enough coating to allow you to cut deep enough to achieve the desired groove width without hitting the aluminum base.
Mark
- Jesus H Chrysler
- Posts: 190
- Joined: Sun Nov 26, 2006 12:03 am
- Location: Asheville, NC
Re: Is there a good reason not to cut 78 lps?
I'm still new to the world of Seeburg jukes but I think I have the red head on it, which would be ok with microgroove. It sounds like shit on my shellac 78s. I think cause it's bottoming out in the groove. I'll just have to cut some tests to find out.
Re: Is there a good reason not to cut 78 lps?
In that case your Seeburg must have been modified at some point with a completely different tonearm as the original mounting would only accept the first generation of Pickering 'Blackhead' carts.
Would love to see some photos if you have time.
And yes, from your description, it sounds as though it's already set up for micro-groove playback... although it's odd that it is also still set for 78 rpm as the typical modification usually also changed the speed to 33.33 at the same time.
Would love to see some photos if you have time.
And yes, from your description, it sounds as though it's already set up for micro-groove playback... although it's odd that it is also still set for 78 rpm as the typical modification usually also changed the speed to 33.33 at the same time.
- Jesus H Chrysler
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- Location: Asheville, NC
Re: Is there a good reason not to cut 78 lps?
Here's a couple. One I took and one snatched from the auction page
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- Jesus H Chrysler
- Posts: 190
- Joined: Sun Nov 26, 2006 12:03 am
- Location: Asheville, NC
Re: Is there a good reason not to cut 78 lps?
I think this an m100a or possibly m100b mech? Don't know if it's original to the unit. I'll check the SN# when I get a chance to narrow down when it was made.
Re: Is there a good reason not to cut 78 lps?
Thanks for the photos - could you take a close up of the cartridge and tonearm please?
It's hard to be sure from the photo above, but the tonearm looks like the original which makes me wonder what type of cartridge is currently fitted as it doesn't appear to be a Blackhead!
Would like to help you get to the bottom of this minor mystery
btw, it's definitely a M100A mech, not a B. Although it looks similar, the B mech is 45rpm only and is quite different under the hood from the A.
It's hard to be sure from the photo above, but the tonearm looks like the original which makes me wonder what type of cartridge is currently fitted as it doesn't appear to be a Blackhead!
Would like to help you get to the bottom of this minor mystery

btw, it's definitely a M100A mech, not a B. Although it looks similar, the B mech is 45rpm only and is quite different under the hood from the A.
- Jesus H Chrysler
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- Location: Asheville, NC
Re: Is there a good reason not to cut 78 lps?
It looks just like the redhead cartridge on the needles site.
- Jesus H Chrysler
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- Joined: Sun Nov 26, 2006 12:03 am
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Re: Is there a good reason not to cut 78 lps?
Also , thanks for your insight, Sue. You're a credit to this group.
Re: Is there a good reason not to cut 78 lps?
You're more than welcome mate - thanks for the vote of confidence!Jesus H Chrysler wrote: ↑Sat May 08, 2021 10:50 pmAlso , thanks for your insight, Sue. You're a credit to this group.
Hmm... interesting. I'd still like to see a close up of the cartridge and tonearm if you have the time.Jesus H Chrysler wrote: ↑Sat May 08, 2021 10:45 pmIt looks just like the redhead cartridge on the needles site.
The reason is that something doesn't make sense. From what I can see from the mechanism photo, the cartridge is fixed to the tonearm using the original type-A Blackhead connections.
Whereas a Redhead cartridge would have a 2-pin connection which usually requires a completely different tonearm.
I'm thinking that perhaps there is some kind of adaptor enabling the use of 2-pin carts on an original 'A' type tonearm... but I'd need a better look to be sure.
Thanks,
- Jesus H Chrysler
- Posts: 190
- Joined: Sun Nov 26, 2006 12:03 am
- Location: Asheville, NC
Re: Is there a good reason not to cut 78 lps?
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Re: Is there a good reason not to cut 78 lps?
Hey thanks mate.
Yup, as you thought, that is a genuine Redhead cart but (as I suspected) connected to an original 'A' tonearm by means of some type of adaptor.
Would like one of those adaptors myself tbh!
So, the upshot of this is that you are indeed all set up to play back microgroove 78s cut on your VR
Like I said before, make sure you sum your channels to mono before you cut and I suggest you keep the max amplitude around +6dB.
All the best...
Yup, as you thought, that is a genuine Redhead cart but (as I suspected) connected to an original 'A' tonearm by means of some type of adaptor.
Would like one of those adaptors myself tbh!
So, the upshot of this is that you are indeed all set up to play back microgroove 78s cut on your VR

Like I said before, make sure you sum your channels to mono before you cut and I suggest you keep the max amplitude around +6dB.
All the best...
- Jesus H Chrysler
- Posts: 190
- Joined: Sun Nov 26, 2006 12:03 am
- Location: Asheville, NC
Re: Is there a good reason not to cut 78 lps?
All good as I suspected. I've got a manual on order so I can sort out the preamp. There's some loose wires and some suspect repairs done that I need to address. Then I I can start poking around in the Capehart flip over 78 changers I got in the same sale. (After I finish replacing the floors and changing the brakes in my car.) .
Re: Is there a good reason not to cut 78 lps?
This is up my street. Check out the Talking Machine Forum. There’s a new post about Colin Hancock making his own acoustic 78’s