Wurlitzer 412 needle cartridge upgrade issues

Hello,

I recently upgraded my Wurlitzer 412 tonearm with a modern 78rpm cartridge from Victory Glass. It was a fairly cheap unit at around $20. Right away I noticed that the treble was very pronounced with almost no bass. I checked the crossover position on the 660 amp and moved it from high to mid. This helped a little but it still sounded a bit distorted on the high end of the signal. After a call to Victory Glass I was told I should upgrade the volume control box with a kit they sell. The kit requires the removal of all of the original components from the original volume control box. The kit includes a replacement pot (dial), a couple of capacitors, a resistor, and a simple wiring diagram that needed a little imagination due to the four position input on my volume box/tonearm pickup cord. The diagram only showed a two wire input. Anyway, I figured it out by tracing which 2 wires went back to the needle. So after doing the upgrade I noticed that the volume increased and a I had gained full volume range on the dial. (The old box had no volume gain after 50%). Unfortunately the high end distortion is still present. If anything, it has gotten worse.

I asked the guys at Victory Glass if a more expensive or less sensitive needle cartridge would help before I got the kit and they were fairly certain the volume box kit would solve this problem. I am starting to think that the problem is over modulation from the new (modern) cartridge. It sounds like the frequency is getting clipped at the needle and just becoming distorted at the amp. I wonder if I could add some sort of attenuating circuit to the volume box to smooth things out a bit.

Does anyone have any experience with this type of modification? Any help will be greatly appreciated/compensated!

Thanks.

Tony

New manufacture ceramic cartridges have a much better high frequency response than the old cartridges did.
So naturally, this would tend to accent older records's worn grooves, sounding raspy.
One solution is to shunt the cartridge input with a 220pf cap, to "calm" the highs.
A 470pf cap could even be used if the situation is severe.

Also make sure the stylus tracking pressure is right for the new cartridge - and adjust as needed. - new cartridges are "lighter" in overall weight than old ones.

Matt, thanks for your reply. How do I check the needle pressure?

-Tony

Tony,
An "old timer" once told me how to check needle pressure--
He said to drop the tone arm onto his finger--if the needle punctured his skin, it was too heavy--if blood shows up, it's way too heavy.
If you don't have tough skin, I guess that you will need to purchase a gram gauge ( talk to your buddy, Denny, at Victory Glass--and tell him I said "Hi", please). Ron Rich

Thanks Ron. Do you think the needle pressure has anything to do with this high end distortion? Or should I focus on adding a capacitor to filter out some of this treble?

Thanks.

IMHO, probably both-- Ron Rich

Color jockey wrote:Thanks Ron. Do you think the needle pressure has anything to do with this high end distortion? Or should I focus on adding a capacitor to filter out some of this treble? Thanks.

"Color" what sort of pickup did VG send you you?

Does it look like any of these?:

http://www.needles4jukeboxes.com/IMG_1771.JPG
http://www.turntableneedles.com/Pfansti ... _3966.html

http://www.stantondj.com/stanton-cartridges/400v3.html

The first two are ceramic and require an input impedance of at least 2 megohms for adequate bass. In addition, the P132 is stereo and both channels must be wired together in order to help cancel out soem of the distortion inherent in old records.

The Stanton is magnetic and was shipped with the old WutlitSound and "Supersound" retrofits along with a preamp.

Rob/NYC

Thanks Rob! This is good info. Victory Glass sold me a Pfanstiehl P51-3. I also picked up the suggested volume box conversion kit that I would assume addresses any compatibility issues… I may have assumed wrong.

So my cartridge is ceramic… "The first two are ceramic and require an input impedance of at least 2 megohms for adequate bass." How and where do I measure the "meg ohms"? And do they sell a cartridge that is a better match with my Wurlitzer 412? Maybe a bigger needle so it doesn't go as deep into those noisy grooves?

The bottom line is that I want to get that nice warm (low frequency) sound that the original cartridge produced. What do I need to accomplish this?

Thanks again for your help.

-Tony

Tony, if you want to measure the input impedance you'll need a meter (Digital or analog) and then set it to the megohm scale (10meg or more) and connect is across the same terminals that the cart connects to.

Make sure that the cart is connected to the 'high" side of the volume pot -NOT the arm. Those primitive magnetic carts had much higher output than the modern ones and since the volume pot comes before any amplification there is no likelihood of overloading and causing distortion.

Your problem comes down to one or more of the following:

Improper impedance load on the cart (too low).

The need for some capacitors to be added across the signal line to reduce treble as per Matt and Ron's suggestions.

The wrong stylus being used. the correct styli for 78's is a 3mil. using a 0.7 or 1 mil will rattle around the bottom of the groove and have lower, noisier output.

These older machine are well before the era that i deal with, so there may be additional steps that can improve things such as building a small preamp/tone shaping module to boost gain and bass.

Signing up and checking-in here might offer some help too:

https://groups.yahoo.com/neo/groups/wurlitzer//info

Finally, I'd double check the installation of the kit you bought. It is possible that a wrong connection is placing an incorrect load on the cart.

Rob

I've used the P51-3 in such jukes as a wurlitzer 1100 with excellent results.
Nice, punchy sound overall.
But as was mentioned, the correct parameters must be implimented - input impedence, etc.
Usually this requires someone with the electronic experience and skills to do.
Not being familier with the 412's input configuration, I can't give any further advice.

Thanks for all of the replies. All great information. One thing I should probably clarify, the sound is actually very good other than the exaggerated treble. I bought a few different caps the other day (waiting for delivery). Thank you Matt Tech! I chose a 220pf, 470pf, and something in the middle. I will test one at a time and hopefully one of them drops the high end frequencies enough without losing to much (any) fidelity. I assume it should just go inline with the signal wire from the cartridge. I may solder it in line with the existing circuit I used in the volume control kit I purchased from Victory Glass. I am just a little nervous about tampering with the layout. It must be designed that way for a reason, but why the ultra high frequencies?! I also think part of the distortion may be from a late 1950's Canadian pressing of Johnny Cash "get rhythm". That record is the biggest high end distortion culprit. I don't think the recording holds up to the earlier pre-war technology. Any thoughts on this?

Thanks again guys.

-Tony

Final update. First of all, thanks again for all of the great feedback and suggestions. I have Solved the high frequency problem. I removed the volume control box and clipped the low pass filter (cap and resistor) that was wired inline from the input to ground. Immediately the bass and mid tones opened up and the harshness of the super high frequency was balanced out (or removed, hard to tell). This low pass filter must have been intended for a later model machine or one that doesn't have an amp with a built in crossover (low/mid/high) selector. Mine is the 660. The only questions I have now is, was the volume control kit I bought for a different model juke? One without the amp with crossover switch?? And, could the open ground in the volume control box be bad for the amp? That low pass filter must have been in there for a reason.

-Tony