A lucky find

Take a look at the description at

Dave M

It would seem to me you could just use an ohm meter on the cartridge and see what the resistance is. If very low it would be the mc and if say

Ummmmm..........

Be EXCEEDINGLY careful in putting a VOM across any phono cartridge, most es pecially an MC cartridge. Some (cheap) VOMS will put as much as 9V through the coils - not a good thing. And batteries will deliver current to their c hemical limits - thinner-than-human-hair wire does not like heat.

Peter Wieck Melrose Park, PA

You have an MM cartridge unless it has an outboard head-amp and/or transformer. Start at 100K. If it sound anemic, move to 47K.

Peter Wieck Melrose Park, PA

Most cartridges (unless it's a really cheap turntable in which case it's a crystal or ceramic cartridge) are moving magnet. At least that used to be the case, the moving magnet coil ones were the exception for the ones who wanted to spend more, and you'd need an extra preamp for it.

Maybe that's changed, with fewer people owning turntables, maybe the ones using them tend to use moving coil cartridges.

But the default is moving magnet.

Michael

Maybe with the older anlaog meters. I so seldom drage out the analog meter for ohms I was not thinking about that one.

The newer digital meters only let a very small ammount of current flow in the ohms position. I mesured a cheep HF $ 5 (free with coupon) meter at less than 2 ma, and a Fluke 87 with less than .5 ma on the low ohm scales.

My good old Sompson 260 will put out just under 100 ma on the low ohms scale.

NT

Good article on that website listed. I have two turntables. The cheap one has a non-removable (as far as I know) cartridge. I dont have a cartridge number, but its an AIWA turntable, and takes an AN-11 stylus. The good turntable has an Audio Technica AT5011E. I also have a spare cartridge from way back, (new in the box), Electro Voice V100.

I'm pretty sure the Audio Technica and the Electro Voice are both MM. Probably the AIWA one too, unless thats a crystal or ceramic.

I imagine there is a place to look them up, but I have not yet tried to find a website that lists them.

As far as using an ohm meter. I do understand the old analog ones are probably not a good idea. I do have a modern digital one (not one of those cheap HF ones). But what about using a VTVM. I may be wrong, but it's my understanding that VTVMs are safe to use on darn near anything. I have two of them, a Heathkit and an Eico.

(Presently the Heathkit one tends to act a bit flakey, probably needs new caps, but the Eico works fine).

But it's probably easier to just look them up by model.

Not to mention..... Both the AT and the EV have FOUR wires coming from them, but when they exit the turntable, they only have TWO (as in RCA plugs). What are the other two wires for?????

Whoooo Boy! I can think of no reason whatsoever that one should ever use a VTVM in these modern times. Sure, loading a Zenith TransOceanic while perf orming an alignment via a VTVM makes some of the things go 'by the book', b ut using a regular high-quality VOM is just fine. Better in many cases. Nor would I ever advocate using a mains-connected VTVM on much audio stuff in any case. Nor do I appreciate them as ancient tools. I do not have enough r eal-estate on my bench to entertain tools that are not useful.

Wheeee.....

A typical stereo phono cartridge of any ilk has four (4) wires coming out o f it. Some (very) cheap devices have only three, sharing the ground between the channels, but I have not seen one of those for over 30 years.

So, we have:

SR/RG (signal right/right ground) SL/LG (signal left/Left ground)

Which goes to Right RCA Jack as follows:

SR to center post. RG to shell (shield).

And the left RCA Jack as follows:

SL to the center post. LG to the shell (shield).

Magically, four wires go to two wires.

There should be a general ground wire in there somewhere - which *SHOULD NO T* go to the pre-amp/amp chassis ground but to either of the shells on eith er of the jacks.

Peter Wieck Melrose Park, PA

One cannot make this stuff up!

On some great and glorious day the plain folks of the land will reach their heart's desire at last, and the White House will be adorned by a downright moron.

H.L. Mencken

A true prophet.. Two in a row; a *long* 16 years (and one a socialist). Hopefully the next 8 years will be better.

It's just like watching The Lord of the Flies now.

I have a Heathkit VTVM I put together over 40 years ago. I had it out a while back just to see if it still worked. It was slightly flakey and I gave it a shot of the Deoxit on the switches and that made it work like it did when I built it.

I don't know what kind of current it puts out in the ohms position. I doubt I will ever use it for anything but maybe where I need a zero center scale meter.

It's easy to tell magnetic from ceramic. Magnetic styli are in a squarish p lastic piece that slides out - or rarely in the case of one of the AT uncli ps downward. Ceramic styli are unencased, and clip in. Old ones have a flip over sidearm to select from 2 needles, typically LP & 78.

The other way to tell them is to wobble the arm slightly when playing. Magn etics let the arm/needle wobble, ceramics don't.

totally pointless.

Each RCA plus has 2 conductors, outer and inner.

NT

Yes, you got a lucky find!

I've bought a very nice receiver (a Proton) where the seller said it didn't work at all, and the reason was that he hadn't read the manual and seen that the receiver needs a jumper between "preamp out" and "amp in" if you aren't using an external signal processor. The original jumpers had been lost at some point and the owner didn't do his research...

Ummm... search the Internet for its part number?

Or, measure its DC resistance with an ohmmeter. If it reads a few ohms, it's certainly a moving-coil amplifier. If it reads hundreds, it's probably a moving-magnet (there are some higher-impedance moving coil cartridges but they're less common).

The numbers you see above are not those of the cartridges... they're the parallel resistance of the phono stage itself, in that setting. The frequency response of any phono cartridge will depend to some extent on the load resistance. The cartridge maker may specify the recommended load.

Cartridges that you can do that with, are almost all moving-magnet (or moving-iron) cartridges. The MM setting, and 47k ohms input impedance, would very probably be the one to choose - that's the industry-standard resistance.

MC cartridges typically have a significantly lower output voltage... plugging them into an MM input will result in very low audio levels. One needs a bunch of additional voltage gain (provided by the preamp in MC mode, by an external "head amp", or by a signal transformer) to use a low-output MC cartridge.

You are addressing someone who *just* discovered nanofarads. Consider his state of mind.

On 5/18/2017 7:18 PM, rickman wrote: > You are addressing someone who *just* discovered nanofarads. > Consider his state of mind.

That and RCA connectors actually have TWO connections.

Sounds like you got a good deal too. I am very familiar with those jumpers. My Altec Lansing commercial power amp has those.

The guy that gave me this preamp did a similar thing. He thought that the RCA jacks marked "Output" were for speakers. That threw me off too, because he had said that, but in a matter of minutes I realized this is not a power amp. Looking it up online confirmed that.

About the only things that I recall using RCA plugs on speakers were some of those really old portable record players from the 50s and 60s. The speakers would unplug using a RCA jack/plug and the speakers lifted off the record player, using special hinges with pins that stuck out, so the speakers could be moved.

That's something I should do with my Heathkit VTVM, use the Deoxit. Maybe that is all it needs.... But I do plan to recap it anyhow. At least the power supply lytics....

I use almost all old tube based test gear, but I normally only work on tube stuff, so I use what matches the equipment.

Lately, I have been working on a lot of solid state stuff. I'd rather work on tubes, but this soild state stuff is my own stuff, so I work on it. I generally use all modern test gear on solid state equipment, except for my old Paco tube signal tracer. That thing works on everything and is probably my most used piece of test gear.

But I like that old tube test gear, for working on tube stuff. My Sencore scope is solid state, but it's still quite old. I recently got all five of the old Eico probes, plus the high voltage probe they sold. So I am now equipped with probes for almost every need. Eico made the best probes ever, and I really had a tough time getting all of them. I'll probably never need the high voltage one, since I dont work on old CRT tvs, but it came with the other probes.

All I need now, is an old 50s era panel truck so I can paint "Radio Repair" on the sides!!!

Oops, I was having a brain fart. Yep, these are STEREO cartridges. They need FOUR wires (or at least 3 if they share the ground).