RIAA to Acoustical Low Gain?

[Marc Hildebrant]

Group,

Just recorded some early 1920's 78's using a standard pickup/RIAA amp.

Using the VPA, I selected the RIAA as input and the acoustical as record type. The gain of the output file really drops. I set the gain slider all the way up, but it's still way down in amplitude.

The other record types do not drop the gian so much.
Is the low gain with the acoustical "record type" correct ?

Regards,
Marc

[Craig Maier]

Did you use a standard LP stylus? You need to use a special 78 stylus else the signal will be very low and quite noisey. LP stylii are around 0.7 mils and 78 stylii are roughly 3 mils (there is a chart in your users manual with the various sizes by record label and record type).

[Marc Hildebrant]

Craig,

I'm not sure what size the stylus is on this pickup. The pickup is an early 1950's GE arm with a variable reluctance type. The turntable is a Rek-O-Cut from the early 1950's.

When I select the other record types in the VPA option, the sound level is normal. Also, the recording sound level is around -10 to -3 dB to start with.
Only when I pick the "Acoustical" record type does the level drop.

Marc

[Craig Maier]

Well, I think that makes sense. When the VPA is set for normal 78s or LPs there is a turnover curve which amplfies the bass more than the rest of the spectrum. Acoustical 78 did not have that curve. So, when you switch the preamp to acoustical, all that low frequency noise from the record will diminish dramatically and the signal will appear to be much lower in amplitude. The bass sound should also become a lot less "honkier" when acoustical is chosen if you know what I mean.

But, you need to figure out what stylus that you are using to get this done correctly. I do know that some GE Variable Reluctance cartridges did have 2 stylii. You could turn a small knob on the top of some of their models to spin between LP and 78 stylii tips. I don't know what model you have there.

[Brian]

Hi Marc
Does your cartridge have a shiny metal exterior on the whole cartridge (making it a GE RPX) or just the front half of it (making it the slightly newer GE VRII)?

Craig is right, most GEs had a twist knob on the top that stuck up through the head of the tonearm. It had a red plastic triangular shaped handle labeled "78" and "LP". Whichever label was facing the front of the cartridge corresponded to the stylus being used. The styli were also color coded - the metal mounting bar that held the diamond (45/33) or sapphire (78) had a dab of paint or the entire metal arm was colored. First, make sure you've got the "78" stylus being used. Then, if you can tell me the color of the mounting arm, I can tell you the diameter.

Here's a link with pictures and more info on the GE variable reluctance cartridges:
http://members.myactv.net/~je205d/mono.htm

The styli are still available and quite inexpensive. Many aficionados prefer the sound of the mono cartridge to that of a modern stereo one - however there are some real advantages to using a stereo one for transfers since you can choose the cleaner of the two signals (one side of the record groove probably has had less wear than the other).

Hope this helps.
Brian

[Marc Hildebrant]

Brian/Craig

Thanks for the info. The turntable/arm belonged to my father, long since gone.

Looking at the pickoff arm, there is a hole in the GE red circle. Must have been the location for the 78/LP turning part...now gone.

The while cartridge is in a shint metal cover.

Looks like I'll need to find a source for a "correct" size stylus.

Marc

[Brian]

Marc

The cartridge is a GE RPX. Here's a link to a source for the styli (you'll need 2 -- one for LP's and one "with 78 option" for $13 each):

http://www.garage-a-records.com/prod...php?prod=501d7

Is there a metal post that sticks up through the hole in the cartridge shell? If so, all you need is the red plastic "switch" cap which are available on eBay for about $10 (search either for GE RPX, GE VRII, GE VR2, or variable reluctance). If there isn't a metal post then you have a single stylus model. Just buy the "with 78 option" replacement. The old stylus just pulls off and the new one slides on. If your Rek-o-kut needs a tune-up, here's a link on how to do a complete rebuild:

http://members.myactv.net/~je2a3/roktips.htm

Usually, all they need is a new drive puck. Fortunately this guy is still rebuilding them:

http://www.vintagelectronics.com/

Good luck.
Brian

[Marc Hildebrant]

Thanks Brian for the links to Rek-O-Kut info. I'll need to rebuild the turntable and get the proper needle

Marc

[Marc Hildebrant]

More Info/GE

Group,

The turntable is a model TR-12 Rek-O-Kut and the cartridge is a GE 105.
Not sure about the needle size.

Marc

[Marc Hildebrant]

Yet More Info

Group,

The needle that I received was a "tip out" style, whereas the needle that I need mounts with a post that is pressed into a hole in the cartridge body.

I'll send the needle back if possible.

The quest to find the correct needle for old cartridges sure is an interesting trip.

Maybe the best approach is to just buy a Stanton 500 model that is in current production.

Marc

[Craig Maier]

The Stanton 500 should substanbtially out perform an old GE variable relucatance cartridge because it has a much higher mechanical compliance and thus a much flatter response. On the other hand, you are using a "massive" old GE tone arm. I do not know how well a high compliance phono cartridge like the Stanton 500 will work with a high mass tone arm - - - I have never tried it. In the old days, those massive tone arms needed low compliance cartridges like the GE type. Today, tone arms tend to be of relatively low mass and work well with high compliance cartridges.

If it were me, I think that I would look for a bargain 1980s vintage turntable with 78 RPM on ebay and then outfit it with the Stanton 500. That is a combo that I am quite confident will work.

[Marc Hildebrant]

Good Point

Craig,

Thanks for the comment. I hadn't considered the tone arm's mass effect that it would have on a Stanton or for that matter any "new" cartridge.

Marc