Moving Coil Pre Preamp

[dmf-fjr]

What is a MC pre preamp? Does it only amplify the signal? What input would you plug its output in to, MC or MM?

 

[Swerd]

What is a MC pre preamp? Does it only amplify the signal?

The are two types of phonograph pick-ups, moving magnet (MM) and moving coil (MC). The MM pick-ups are much more common, and cost less than the MC pick-ups. Typical MM pick-ups produce signals in the range of 5 millivolts (mV), and MC pick-ups produce weaker signals, as low as roughly 0.5 mV to as high as 2.5 mV.

Before those signals can be sent to a receiver, integrated amp, or audio pre-amp, they have to be amplified to about 1.1 V (that's 1,100 mV). The MC pick-ups need more amplification than the MMs need. Both MM and MC pick-ups also need RIAA equalization. And both types of phono pre-amps do that as well.

What input would you plug its output in to, MC or MM?

If you have a receiver with MM or MC input jacks, plug the phono signal cables from your turntable directly into them, depending on what type of pick-up you have. Your receiver has built-in circuits that amplify and equalize those signals.

If you have a separate phono pre-amp, connect the phono signal cables to the MM or MC inputs as appropriate. And, connect the pre-amp's outputs to any available pair of audio input jacks, as long as they are not MM or MC. Don't do the needed amplification and RIAA equalization twice.

 

[dmf-fjr]

The are two types of phonograph pick-ups, moving magnet (MM) and moving coil (MC). The MM pick-ups are much more common, and cost less than the MC pick-ups. Typical MM pick-ups produce signals in the range of 5 millivolts (mV), and MC pick-ups produce weaker signals, as low as roughly 0.5 mV to as high as 2.5 mV.

Before those signals can be sent to a receiver, integrated amp, or audio pre-amp, they have to be amplified to about 1.1 V (that's 1,100 mV). The MC pick-ups need more amplification than the MMs need. Both MM and MC pick-ups also need RIAA equalization. And both types of phono pre-amps do that as well.
If you have a receiver with MM or MC input jacks, plug the phono signal cables from your turntable directly into them, depending on what type of pick-up you have. Your receiver has built-in circuits that amplify and equalize those signals.

If you have a separate phono pre-amp, connect the phono signal cables to the MM or MC inputs as appropriate. And, connect the pre-amp's outputs to any available pair of audio input jacks, as long as they are not MM or MC. Don't do the needed amplification and RIAA equalization twice.

I have both a Dunlavy MC Pre Preamp, and a phono preamp that will take either MM or MC. My cartridge is a Supex SD 900 Super which has extremely low output. Many MC preamps will not work with it. If I run it through the Pre Preamp, and then plug it into the MC input, it seems to work. But my question is whether the Pre Preamp also provides RIAA correction or only amplification.

 

[Swerd]

I have both a Dunlavy MC Pre Preamp, and a phono preamp that will take either MM or MC. My cartridge is a Supex SD 900 Super which has extremely low output. Many MC preamps will not work with it. If I run it through the Pre Preamp, and then plug it into the MC input, it seems to work. But my question is whether the Pre Preamp also provides RIAA correction or only amplification.

Your question is beyond my experience. I own a standard MM cartridge, and use a standard MM type phono pre-amp.

I had to look up what a Supex SD900 Super is. It's an unusually expensive MC cartridge with an output of 0.2 mV. Compared to 0.5 mV, that 2.5 times less output. When I Googled "Phono pre-amp for supex 900 super cartridge" I found this:

Phono Stage / Preamp Recommedation for Supex 900 Super- Vinyl Engine

www.vinylengine.com

Read the 2nd post on that page, by 'bonzini'. He said this:

… what you need in the way of amplification depends on what you've got. If you have a preamplifier, integrated amplifier, or receiver WITH a phono setting, then you may need nothing at all provide that the gain can be set for MC. If your equipment is MM-only, then you need a step-up device, either an amplifier or a transformer, to convert the low-voltage high-current MC output to a higher voltage suitable for the MM input. On the third hand if you have no phono section at all, then you need a complete phono amplifier (you might wish to get one of these as well if you feel your phono section is substandard).

Read the rest of bonzini's post and see what he says about step-up transformers.

Remember that step-up devices are there to convert from low-output MC to higher-output MM voltages. They leave the issue of phono equalization to the MM section. A line level input on the typical receiver of today does not have phono equalization. For this you need a full add-on phono stage.

Does any of this answer your question?

 

[Mikado463]

one of the key things to look at with respect a phono pre and a low output MC cartridge is the amount of 'gain' it provides for a MC cartridge. Generally speaking if your cartridge output is less than .5 mv you will want 64 db of gain or better.

Also the better phono pre's give you much more flexibility with respect to loading.

 

[lovinthehd]

I'd heard of Dunlavy speakers but phono pre-amp I'm coming up with zilch on. There any further model identification for that unit? How about the other phono stage, what is it? Why do you have this cartridge and these phono stages if you don't know about them? Inheritance?

 

[TLS Guy]

I'd heard of Dunlavy speakers but phono pre-amp I'm coming up with zilch on. There any further model identification for that unit? How about the other phono stage, what is it? Why do you have this cartridge and these phono stages if you don't know about them? Inheritance?

That is because the Dunlavy was a transformer and not a preamp.

 

[Mikado463]

again, simply put the Op's cartridge has only .2mv of output, it needs gain !!

 

[lovinthehd]

That is because the Dunlavy was a transformer and not a preamp.

Well using transformer instead in my search I found a Audio Standards unit Dunlavy had something to do with.. https://www.audiogon.com/listings/phono-audio-standards-corp-mx-10a-audio-standards-corp-mx-10a-mc-pre-preamp-2014-11-11-preamplifiers but perhaps my google fu is lacking today.

 

[TLS Guy]

What is a MC pre preamp? Does it only amplify the signal? What input would you plug its output in to, MC or MM?

Several things here.

It is not only the output, that is different between MC and MM cartridges, but the impedance. The latter is just as significant, if not more so than the voltage output.

So you can either use a transformer, or a an MC preamp. However you can be certain a transformer will present the correct impedance match and increase voltage.

If you use a transformer then you connect to an RIAA input and not a line input.

If you use an MC preamp, then you connect to a line input, and certainly not an RIAA input. If you do the latter you will have two RIAA corrections which will not sound correct.

Now I'm pretty sure the Dunlavy uses transformers and is NOT a preamp, but I can not be certain. However if the unit plugs into the AC it is a preamp, if it does not then it uses transformers.

Now your cartridge is low output, about half of most MCs . So yes, you will need a high gain MC preamp.

Now as I understand it, Dunlavy produced his transformers specifically for that cartridge. So if that Dunlavy unit does not plug into the AC, then it is a transformer and you need to plug it into an RIAA equalized input.

Lastly that is an old cartridge and may not be working correctly. It comes from an era when magnets lost flux over time. The other issue is that the stylus is not user replaceable on an MC. I doubt there is anyone one on earth who can rebuild that cartridge. You should have the stylus professionally examined and checked for wear.
If it is worn you will ruin your record collection.

I have done a search for you and high gain MC preamps are not plentiful. This one claims 75 db of gain on the MC input. If true, then this is what you need, if that Dunlavy unit is not the one designed for your cartridge.

Unfortunately Jerry Raskin who owned Needle Doctor died recently. Needle Doctor is no more and closed. Jerry would have been able to tell you exactly what to do.

However, I have to stress that you must have at least the cartridge stylus checked before you spend any more money.

My last thought is that MC cartridges have a habit if being far more trouble than they are worth. My late father was keen on them, but I personally never have been. That is probably a hanging offence to the Audiophool crowd.

 

[TLS Guy]

Well using transformer instead in my search I found a Audio Standards unit Dunlavy had something to do with.. https://www.audiogon.com/listings/phono-audio-standards-corp-mx-10a-audio-standards-corp-mx-10a-mc-pre-preamp-2014-11-11-preamplifiers but perhaps my google fu is lacking today.

I think you did quite well. This is the note.

(Produced by John Dunlavy when he was with ASC in 1979. This is a really well built MC phono pre and at $400 in 1979 was quite pricey. If you feel the weight of it, it is simply one massive transformer inside. The wood sides are in great condition for the age, the leather wrap is also in great condition-just needs some leather conditioner. The face and rear panel are a little discolored due to age (brass or bronze finish that is tarnished). I chose not to clean the metal to avoid washing off the printing. No big scratches, gouges or marks. Looks vintage from the style and power cord but aged really well. This only had one owner for the past 35 years until I got my hands on it recently. I did test it and got good clean sound but only had my MM Clearaudio to test with which wasn't the correct match. Keep in mind that this is a vintage piece but not much can go wrong with a giant spool of copper wire? It's heavy but small so shipping shouldn't be bad from 15208 at about 10 lbs).

This unit is stated to be heavy. Since its date is 1979, there would have been no devices available to make a true MC preamp. So from that time, this would be a transformer and then a preamp to do RIAA correction and bring it up to line voltage. You can infer this, by comment about the weight.

 

[Mikado463]

Several things here.

It is not only the output, that is different between MC and MM cartridges, but the impedance. The latter is just as significant, if not more so than the voltage output.

So you can either use a transformer, or a an MC preamp. However you can be certain a transformer will present the correct impedance match and increase voltage.

If you use a transformer then you connect to an RIAA input and not a line input.

If you use an MC preamp, then you connect to a line input, and certainly not an RIAA input. If you do the latter you will have two RIAA corrections which will not sound correct.

Now I'm pretty sure the Dunlavy uses transformers and is NOT a preamp, but I can not be certain. However if the unit plugs into the AC it is a preamp, if it does not then it uses transformers.

Now your cartridge is low output, about half of most MCs . So yes, you will need a high gain MC preamp.

Now as I understand it, Dunlavy produced his transformers specifically for that cartridge. So if that Dunlavy unit does not plug into the AC, then it is a transformer and you need to plug it into an RIAA equalized input.

Lastly that is an old cartridge and may not be working correctly. It comes from an era when magnets lost flux over time. The other issue is that the stylus is not user replaceable on an MC. I doubt there is anyone one on earth who can rebuild that cartridge. You should have the stylus professionally examined and checked for wear.
If it is worn you will ruin your record collection.

I have done a search for you and high gain MC preamps are not plentiful. This one claims 75 db of gain on the MC input. If true, then this is what you need, if that Dunlavy unit is not the one designed for your cartridge.

Unfortunately Jerry Raskin who owned Needle Doctor died recently. Needle Doctor is no more and closed. Jerry would have been able to tell you exactly what to do.

However, I have to stress that you must have at least the cartridge stylus checked before you spend any more money.

My last thought is that MC cartridges have a habit if being far more trouble than they are worth. My late father was keen on them, but I personally never have been. That is probably a hanging offence to the Audiophool crowd.

Interesting, the Technolink phono-pre you provided the link to appears to be somewhat misleading ?? when you click on the pic of the box it comes in it says 40 db of gain with and additional 'adjustable' 20 db of gain ? not so sure of adj loading either ?

 

[Mikado463]

the other option for a low output MC is a 'step up transformer' ahead of a MM phono pre.

 

[lovinthehd]

Or just get a less fussy cartridge (and as was mentioned make sure the current one is worth further accommodation at least).

 

[Verdinut]

Or just get a less fussy cartridge (and as was mentioned make sure the current one is worth further accommodation at least).

Agree about a less fussy cartridge.

The famous Decca moving coil cartridge had an amazing performance. But the main problem with it is that it was hard on record grooves, mainly due to the required tracking force. If you were using such cartridge, you had to make sure you could get extra copies of your preferred vinyls, or transfer them to reel to reel tape at first or second playing.

That's most likely the reason why it lost popularity over time as compared with a good moving magnet one.

 

[Mikado463]

Agree about a less fussy cartridge.

The famous Decca moving coil cartridge had an amazing performance. But the main problem with it is that it was hard on record grooves, mainly due to the required tracking weight. If you were using such cartridge, you had to make sure you could get extra copies of your preferred vinyls, or transfer them to reel to reel tape at first or second playing.

That's most likely the reason why it lost popularity over time as compared with a good moving magnet one.

todays modern MC cartridges combined with updated stylus designs have totally eliminated that. Truth be told there has been damage done with too light a tracking force. Today I'd venture to say most cartridges track between 1.8 and 2.2 grams.

 

[TLS Guy]

Interesting, the Technolink phono-pre you provided the link to appears to be somewhat misleading ?? when you click on the pic of the box it comes in it says 40 db of gain with and additional 'adjustable' 20 db of gain ? not so sure of adj loading either ?

So, yes that is misleading.

The OP seems to be scared off. However I agree with you, that his best bet is transformers and connect to the MM RIAA input.

This is a seventies era MC before powerful rare Earth magnets. That is why the output is low.

The OP will have to decide if this cartridge is worth all the trouble. I have not looked, but I doubt anyone is around who can rebuild this cartridge to replace the stylus. So likely this cartridge is already unuseable, or will become so with continued use. I can tell you that I would not be devoting significant funds and trouble to this project.

 

[TLS Guy]

Agree about a less fussy cartridge.

The famous Decca moving coil cartridge had an amazing performance. But the main problem with it is that it was hard on record grooves, mainly due to the required tracking weight. If you were using such cartridge, you had to make sure you could get extra copies of your preferred vinyls, or transfer them to reel to reel tape at first or second playing.

That's most likely the reason why it lost popularity over time as compared with a good moving magnet one.

The Decca is not moving coil. It is variable reluctance moving iron. The load like any MM cartridge. I own three of them. I have owned them since the advent of the Decca ffs MK II in the mid sixties.

Below is my original MK II converted to 78 RPM cartridge. Stay tuned for a new vintage project about this soon.

I had a hand in the development of the Decca ffss. I was a young kid in short pants, and Percy Wilson the technical editor of Gramophone, was bemoaning that no cartridges could track below the 7 to 10 GM range. So I built a mono MC cartridge with the stylus suspended on a nylon cord. It tracked at 3 GM. This was important as Cecil Watts had shown that this was the maximum tracking force that would not cause permanent groove deformation.

I showed one to Stan Kelly of Decca at the Audio Fair. The Decca range followed, but variable reluctance and not MC.

Decca Gold MK VI.

They are very detailed cartridges, but vertical compliance is somewhat limited.

 

[Bucknekked]

The Decca is not moving coil. It is variable reluctance moving iron. The load like any MM cartridge. I own three of them. I have owned them since the advent of the Decca ffs MK II in the mid sixties.

Below is my original MK II converted to 78 RPM cartridge. Stay tuned for a new vintage project about this soon.

I had a hand in the development of the Decca ffss. I was a young kid in short pants, and Percy Wilson the technical editor of Gramophone, was bemoaning that no cartridges could track below the 7 to 10 GM range. So I built a mono MC cartridge with the stylus suspended on a nylon cord. It tracked at 3 GM. This was important as Cecil Watts had shown that this was the maximum tracking force that would not cause permanent groove deformation.

I showed one to Stan Kelly of Decca at the Audio Fair. The Decca range followed, but variable reluctance and not MC.

Decca Gold MK VI.

They are very detailed cartridges, but vertical compliance is somewhat limited.

Mark
Is there anything related to turntables and tape decks that you haven't had a hand in?
Seriously, I am reading this thread and just shaking my head at the treasure trove of information that you hold in your head. I need to get a bag of popcorn and just read some of your threads again.

I am seriously happy with my Pro-Ject turntable and modest stylus thats on it.
Best, most trouble free TT I have owned. Don't have to mess with it or fuss with it. It just works.
Maybe that's just too easy for some folks.

 

[Bucknekked]

The are two types of phonograph pick-ups, moving magnet (MM) and moving coil (MC). The MM pick-ups are much more common, and cost less than the MC pick-ups. Typical MM pick-ups produce signals in the range of 5 .

Swerd
Totally unrelated to this thread: it will be 4 years next month that I took delivery of my Salks.
Still totally in love with them. They still look like the day they walked in the joint. Gorgeous.
I still play them every day. One of the best investments I've ever made in audio.
Two High Fives coming your way for the help and guidance on those. I would not have taken the risk without your assurances.