[andyr]

For several years I have been running a "Phantom Audio" (made in Oz) Phono Stage plugged into a line-stage preamp.

Like many Phono Stages, this is a 47K MM board with a pair of 10:1 step-up transformers to provide the extra gain needed for an MC cartridge.

My cartridge is a Benz Ruby 2 ... 0.3mV output.

Luckily, the MM board has enough gain that I don't actually need to use the step-up transformers ... yes, I have to turn up my preamp volume control to 4/5ths but the result is loud enough.

If I use a 470 ohm res to load the MC cartridge then it "sees" the same 'R' load that it did when it was plugged into the MM RCA inputs (the 47K MM load divided by the square of the step-up transformer turns ratio).  The easiest way to do this is to buy a pair of RCA 'Y' adapters - 2 females in and 1 male out.  Then you can put the phono cable and an RCA plug which has the load resistor soldered across it, into the inputs and plug the output into the MM RCA input sockets.

With the phono cable plugged into the MC input RCAs - ie. going through the step-up transformers - the sound stage was barely wider than the speakers.  When I bypassed the step-ups and plugged the phono cable directly into the MM RCA inputs, the sound stage opened up wider than the speakers and became much deeper.  The music became much more "involving", too.

And, yes, the turntable was level and the cartridge VTA, VTF, azimuth and anti-skate were all adjusted correctly!

My conclusion on the above is that step-up transformers do not deliver all the extremely low-level signals that influence soundstage ... as the magnetic coupling from primary to secondary just does not work as effectively at low signal levels as it does at high signal levels - and soundstage information involves low signal levels!!

So, I will no longer use step-up transformers.

Regards,

Andy

[Marbles]

Andy,

I wouldn't paint all transformers with the same wide brush.

There are some wonderful ones out there.

Lundahl, Jensen and S&B make some really nice ones.

[capo]

You tried ONE step-up and make a BLANKET conclusion?

[JoshK]

Andy,

I have never tried a step up trannie as I have a high output MC cart, but I think there can be a number of things at play here, not the least of which can be the attenuator in your line stage is less than optimal.  As others eluded to, it would be hard to derive a hard fast conclusion about trannies from this experiment.  However, I would probably use the set up your using, instead of using a trannie if it provide the end result simply because less is more, you know?

Cheers and welcome...

[andyr]

You tried ONE step-up and make a BLANKET conclusion?

Yes, mate ... because all step-up transformers work on the same magnetic principles - a signal comes in through the primary (the cartridge signal) and it gets amplified through the transformer (via the 1:10 turns ratio) to come out of the secondary winding.

What I am suggesting is that this magnetic coupling fails at low input signal levels - ie. the basic concept of a step-up transformer is flawed ... just as any active gain stage has (different) flaws!!.

But, yes, there are lots of companies out there flogging their own "special" step-up transformers.  However, they all work according to basic electromechanical laws.

Regards,

Andy

[michael w]

All transformers have sonic consequences .

Most will degrade the sound.

One or two will sweeten it euphonically (eg. the Koetsu).

Best bet is to match the cartridge to your phono stage and run the cartridge straight in, usually at 47k.

 

[lcrim]

I don't have a MC but a MM and have somewhat similar issues at least with regard to gain.  
My analog front end is part of a system that has a Decware SET amp (the Select) that was designed to reach full output with a 2 volt input from a source.  The amp has a pair of inputs that pass through a gain control and another set of inputs that are straight through allowing the use of a preamp.  I use an AE-3 from AES(Cary) and it has 20 dB of gain and my phono pre, the ASL mini phono is advertized as having 57 dB of gain but as it uses a pair of 12ax7's it seems more likely that the gain is around 36 dB.  I wasn't sure that the active preamp was a good thing because of the Decware (Zen) philosophy of keeping the signal path short and uncomplicated but in a practical sense I needed more headroom for orchestral and rock music though with most small jazz ensembles, everything sounded fine.
I am still not sure if the AE-3 adds anything but greater utility, as I am hearing greater detail and bass but the audiophile aversion to active preamps is something I understand yet the gain has to come from somewhere.  My cartridge (Goldring 1012) has quite high output @ 6.5mv but w/o lots of gain the Stones or Bach just don't sound as dynamic as they should.  Where do you get that gain from and what messes w/ the music the least?

[andyr]

All transformers have sonic consequences .

Most will degrade the sound.

One or two will sweeten it euphonically (eg. the Koetsu).

Best bet is to match the cartridge to your phono stage and run the cartridge straight in, usually at 47k.

 

Michael,

U say "match the cartridge to your phono stage and run the cartridge straight in".  Yes, that's what I'm doing at the moment (Benz MC @ 0.28mV straight into my MM Phono Stage but I have to turn the volume control of my preamp up to 4/5ths to get to my "normal" listening level.

I'm lucky - some other MM Phono Stages might not provide as much gain as mine so, for a low output MC, you need some method of increasing the output.

I agree with you that "all tfs have sonic consequences and most degrade the sound" ... but so do active stages - although I tend to think that a well-executed head-amp IS the way to go!

Regards,

Andy

[michael w]

Hi Andy,

Only thing is that's not what you're doing.

0.28mV is insufficent for any MM phono stage without help.
You need at least 0.40/0.50 mV.

My old Koetsus were great going straight into the old ARC SP8/SP11 preamps which were electrically MM but with high gain.

The problem with headamps is that they add lots of extra wiring and circuitry into the equation with an attendant increase in noise and loss of transparency and soundstage distortion.

Not my cup of tea.

[andyr]

Hi Andy,

Only thing is that's not what you're doing.

0.28mV is insufficent for any MM phono stage without help.
You need at least 0.40/0.50 mV.

My old Koetsus were great going straight into the old ARC SP8/SP11 preamps which were electrically MM but with high gain.

The problem with headamps is that they add lots of extra wiring and circuitry into the equation with an attendant increase in noise and loss of transparency and soundstage distortion.

Not my cup of tea.

Michael, old mate,

You said: "0.28mV is insufficient for any MM phono stage without help.
You need at least 0.40/0.50 mV."

Well, yes ... probably for most MM phono stages.  However, the Phantom Audio phono stage which I have was deliberately designed with higher-than-normal gain bcoz the dealer that sells them (Mike Kontor of Leading Edge Audio here in Melbourne) likes also to sell you a "passive preamp" (which sucks out gain!).

When I have this MM phono stage in front of my active preamp, I have sufficient gain so that I can get my normal listening level at 3/4 or 4/5 of the preamp volume control - ie. it's fine!

You also said: "The problem with headamps is that they add lots of extra wiring and circuitry into the equation with an attendant increase in noise and loss of transparency and soundstage distortion."

Again well, yes ... probably for most headamps.  However I know of one headamp which is a very simple circuit, battery powered, which does not suffer from what you describe.  This is a 60mm x 40mm PCB which fits inside the phono stage case - only problem is ... it has a fixed cartridge 'R' loading of about 125 ohms and my Benz Ruby 2 likes at least 470 ohms.  Bummer!!

If you're in Melbourne ... come round for a listen!

Regards,

Andy