Many excellent MM and HOMC cartridges have an output of only 2 - 2.5 mV and therefore require the volume control on the amplifier to be turned up to well past 1/2 volume to match the output of cartridges with higher output. For example my Ortofon 2M Blue outputs 5mV while my Denon DL110 outputs only around 2mV ( in fact it is rated at 1.6mV).
Is it possible to DIY a simple 2:1 step up circuit that would boost this low output without adding distortion or noise while matching the requirements of both the cartridge and the preamp ?
Is it possible to DIY a simple 2:1 step up circuit that would boost this low output without adding distortion or noise while matching the requirements of both the cartridge and the preamp ?
2:1 implies reduction.
No circuit can achieve what you want without adding noise and distortion.
And anyhow, why? One of the purposes of a volume control is to normalise the gain between different sources. The lower level source will obviously suffer some noise penalty.
A step-up for MM? Certainly not impossible, but definitely not trivial to do properly. The low required gain does not make it any easier.
What are the realistic quality requirements? What cart, what amp, etc? If the requirements are not high, a single opamp stage will be an easy solution.
No circuit can achieve what you want without adding noise and distortion.
And anyhow, why? One of the purposes of a volume control is to normalise the gain between different sources. The lower level source will obviously suffer some noise penalty.
A step-up for MM? Certainly not impossible, but definitely not trivial to do properly. The low required gain does not make it any easier.
What are the realistic quality requirements? What cart, what amp, etc? If the requirements are not high, a single opamp stage will be an easy solution.
OK, point taken, Maybe it was a silly idea.
The cartridge in question is a Denon DL110 into a ProJect Phonobox SE II using the MM stage.
The cartridge in question is a Denon DL110 into a ProJect Phonobox SE II using the MM stage.
Cheers Udok.
That's the sort of thing I was thinking about.
Can you provide a more detailed schematic circuit please ?
In particular the type of opamp etc.
That's the sort of thing I was thinking about.
Can you provide a more detailed schematic circuit please ?
In particular the type of opamp etc.
Almost any mc stage has very low input impedance to properly load mc cart. That does not suit mm carts, they typically need 47k ohm load. I tried what you suggested, it does not work. No harm in trying. But use logic...what happens when some signal source requires high impedance load and you load it with very low impedance, only few ohms. It messes up the output signal no almost nothing and messes up riaa curve too...
Its like driving speakers with cd output directly.
Some MC stages do have provision for a 47k load, in fact that was the recommended load for many MCs at one time, including the Denon.
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Like which ones?
Or other way around, which famous mc preamps have 47k ohm input?
Just curious...
Or other way around, which famous mc preamps have 47k ohm input?
Just curious...
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I seem to recall a fair number of MC preamps have had 47k as the standard input R soldered in, with optional sockets for paralleling a smaller resistor.
Not sure about current units, but it wouldn't hurt. Here's one. Sutherland Engineering | Elegant. Simplistic. Minimalistic Design.
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Hi, One thing I didn't see mentioned earlier is that if you boost the signal is to be aware that some MM stages are fairly easy to overload. A gain of 2 would be fine, more dubious. I have a DL110 and don't find the output to be much different from several others I have. I completely agree that just turning up the volume is the way to go. Anthing you add to the path between the cartridge and preamp will either add some noise or alter the response. Keep it the way it is and enjoy the music.
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