Hagerman Piccolo Zero: New transimpedance head amp

I think the input resistance of the current driven phono stage is in parallel (not in series as per your equation) with the internal impedance of the cartridge, but I am open to discussion about that.  Anyway, my net experience with two very different current driven stages and three different LOMC cartridges is that the input impedance of the stage, which must be some finite but very low value above zero, plays into the resulting sonics.  So, it's not just whether you have enough net gain but also how the cartridge can drive that input impedance. The result is that the SQ is not always predictable.  Every pairing of cartridge with current driven stage is a new experience.  Where data are available, I found the input impedance of various units to vary between 2 ohms and up from there to about 10 ohms.

It should be noted that tonearm wiring DCR should be added to the internal cartridge impedance for your calculations.  This can often be 1-2Ω which becomes substantial in relation to the super low impedance cartridges.

dave

Interesting. Thanks @intactaudio , think I’ll just make a JavaScript calculator where I can plug in different parameters including cable + input resistance. 1-2 ohms seems awful high for 1.2m of cable, even at these small gauges (~ 24 - 26 AWG?). Is a lot of that from the physical contact points?

@lewm

Yeah I suspect you’re right on the matching. It’s not just about gain, though that is an important factor. I ran the Colibri at +12dB level last night (19dB "estimated" head-amp gain) and it was loud enough but still sounded bad lol. I’m not sure why the input resistance of a transconductance phono would be in parallel, though (e.g. loading resistors for voltage mode head amps are in parallel because it makes sense there). Does anyone else have a comment on that?

The thick wire that nets a low DCR also restricts movement so from the cartridge to the din connector is typically 12" of #36 or #37 which puts you at about 1/2Ω per foot.   I have an early Schick and a Schröder and both are in the 1Ω range from pins to RCA so that becomes 2Ω since they are in series.  

dave

@mulveling It is great to see your inquisitiveness has now landed you in Head Amp Territory, in use these have proved to be very impressive to myself and for certain music in my own system, the use of the Head Amp surpasses any SUT experienced on the same music genre to date.

As for the Head Amp in use in other Systems, I have heard it used with Miyajima, Ortofon, Audio Note IO and Sumiko Pearwood, where the H'-Amp has excelled as  comparative device to both In Built MC stages and SUT's.

If like myself, the investigations are taking place around tracks that are well known, I can' help but be very confident that there is to be a music genre discovered that will transcend your experience all ready had to new levels.

One more consideration to ponder if the Head Amp becomes the mainstay. The he TA could become a design to have the Signal Path as a Continuous Wire > Cart' Tags to RCA Phono Connectors ??.

I have recently heard this on a TA I know very well, where PC Triple C has been used as the Signal Path Wire.

  , 

@mulveling So, almost 3 months out, have your initial views changed at all on the Piccolo Zero or how it compares to other step-up alternatives? Has a little time shed any more light on ideal cartridge matching?  It looks like a great product!

Agree, would love an update

"Head amp" usually refers to any outboard device that adds gain but not RIAA correction to the phono signal, ahead of the phono stage.  These days, a head amp can be current driven or voltage driven.   The Piccolo comes either way, I think.

Dear @jobeare ​@tomic601   : " It looks like a great product! "

A cartridge develops voltage not current, then wh use a current design with a voltage audio item. Has no sense.

That to some audiophiles like it to use current phono stage/head amps designs means almost nothing, the real issue is that's a wrong road to go no matters what and again that " any one like it " means only that : thet he like it even if it's wrong but this is more or less usual in the audio world with several eaxamples of wrong audio items ( for whatever reasons ) where audiophiles just touted everywhere like the Dava cartridge or VIV tonearm and ovbiously current design. Obviously too that is way more easy the current phono stage design against a voltage one.

Current design is something very old technology and the first phonolinepreamp and head amp came from Classé Audio from Canada with its NIL ( Natural Load Impedance ) that was in the end of the 70's early 80's and guess what: I owned both with out knowing were current designs, I sold both.

Regards and enjoy the MUSIC NOT DISTORTIONS,

R.

A cartridge develops voltage not current, then wh use a current design with a voltage audio item. Has no sense.

100% wrong. One of the most misinformed comments I have ever seen on this forum.

High output moving magnets typically produce higher voltage and lower current relative to most low output moving coils. Conversely low output moving coils produce much lower voltage and therefore much higher current than typical high output moving magnets.

Here is an explanation -

A phono cartridge is essentially an electric motor. It turns the mechanical power that the record puts into moving a stylus into electrical power. It does this by placing a magnet nest to a coil of wire and moving one with relative to the other. This varies the magnetic field in the coil and produces electrical power.

So for the same mechanical input both MM and MC cartridges should produce the same amount of electrical power (and in fact they do) so why are MM cartridges described as “high output” and most MC cartridges “low output”.

The terms high and low refer to the output voltage from the cartridge not the output power.
Output voltage is determined by the number of turns of wire in the coil which equals extra weight so most MC cartridges have only a small number of turns of wire on the coil so produce a proportionally lower voltage (about a 10th) than a MM cartridge.
However electrical power is voltage x current so for the same mechanical input a MC cartridge can deliver 10 times the current of an MM cartridge.

for more info 

@dover 10+ I think the better analogy would be a generator not a motor, but they are the same thing in reverse. 

I have a Channel D Seta L Plus. It can be used in both voltage and transimpedance mode. The Atlas SL has more gain and sounds better in transimpedance mode, but the Hyperion has more gain and sounds better in voltage mode. So, it depends on the cartridge. The best predictor is the cartridges impedance. IME cartridges with an impedance below 5 ohms work best in transimpedance mode, between 5 and 10 ohms is neutral and over 10 ohms works best in voltage mode. 

@mulveling That is way too much math for me. I think @lewm is correct, they are parallel. 

@mijostyn  : My post is rigth: a cartridge develops voltage.

R.

@mulveling - Thank you for the kind words and posting results of your experimentation. I ran the calculations and input impedance of PICCOLO ZERO comes in at about 0.02 ohms at 1kHz. This is purely dependent on the gain/frequency characteristic of opamp in use. 

@rauliruegas - I'm sorry, but that is not how Faraday's Law of Induction works. Yes, a coil moving within a magnetic field generates an EMF (measured in Volts), as a function of velocity. When the coil is open circuited, you get a voltage. This is how most cartridges are operated. When the coil is shorted however, the EMF forces a current to flow, creating a magnetic field equal and opposite. See Lenz. There is no output voltage, as it is a short circuit.

Therefore, a cartridge can develop a voltage, current, or power. The latter when loaded somewhere between zero and infinite ohms. Seriously, are you trying to say our transimpedance stages do not work? 

Dear @hagtech : Of course not, obviously it works.

I know very well your whole explanation that between other gentlemans as atmasphere werein a deep and hot long thread only because that EMF/Lenz.

I think that maybe I can share the link of that thread,is a learning one for sure..

R.

@rauliruegas My apologies. I thought you were saying cartridge is not pumping out current when used with transimpedance stage. 

Curious if anyone has insight into the differences, if there are any, in technology (or sound character) between the Piccolo Zero and the Sutherland SUTZ? They seem like basically the same thing yet the Piccolo Zero is so much more accessible and space-friendly.

After all the rave reviews, I’m still considering switching to the transimpedance headamp approach with a Piccolo Zero (or maybe even a Sutherland SUTZ) - coming from an SUT, a Quadratic MC-1, which I find very good, and low impedances cartridges (6-10 ohm) - dynavector, hana umami, etc.

Interested in recent thoughts from anyone who has made a similar comparison

(@mulveling - given your extensive experience with the MC-1, any comments on the two units would be especially useful.)

I did it but not with a Piccolo. I did it with a BMC MCCI and my aural results are to be found near the top of this thread. (1) where the cartridge has a very low internal resistance, it does make significant current output and is very good for driving a transimpedance stage. So there is a definite advantage with gain for cartridges that have a very tiny voltage output AND a very low internal R. (2) listening results are not always predictable. In other words, if you think you "know" the sound of a particular cartridge, that sound may vary surprisingly when driving a transimpedance phono stage. This can be good or disappointing. My guess is that this is because the stage has some very low input impedance greater than zero, and each cartridge will drive that stage differently depending upon ITS internal impedance. (Ideally, a TI phono stage should have zero input impedcance.)

So you have to try it to see if you like it. Ultimately I sold my BMC and went back to voltage drive.

A cool experiment would be to get hold of both versions of the Piccolo, since there is an older voltage drive version and compare them. So far as I know, the TI version may be nothing more than a current to voltage converter at the front end followed by the very same circuit downstream that adds gain in the voltage domain.

(@mulveling - given your extensive experience with the MC-1, any comments on the two units would be especially useful.)

@jobeare I still really like my Zero a lot - just listened to it last night, actually. It gives you a whole lot of the weight, passion, and tonal density of a good SUT. It’s definitely a more hit-or-miss match with cartridges than SUT or FET based MC stages. I’ve found very good results with Koetsu (Blue Lace), and really good results with traditional SPUs.

SPU Classic GM spherical has a particularly synergistic match with Zero. LOTS of "musical energy", and such a fun sound in this combo. Plenty of output signal level with the 2nd highest gain setting of the Zero. This level would be roughly comparable to a 30x SUT on a 0.3mV Koetsu. The Meister Silver is also a great match to Zero. But I’m sort of in awe of how great the Zero + SPU => $270 + $1100 combo sounds! Very fun and engaging sound.

The Quadratic SUT is a good one, but it’s definitely a little tilted in favor of bass frequencies, and a little relaxed / recessed up top. Just depends on your setup, how well that works. I spoke with the MC-1’s designer once, and he advised lifting VTA slightly to counteract this. The Zero sounds like a rather "neutral" SUT, but with most of the weight and fullness you’d typically associated with the latter. Think the Quadratic will still give more powerful bass, in most cases. Zero is also a little noisier than you’d get with a good SUT setup or a really quiet voltage mode MC stage (like Pass Labs) - that’s the "cost" with these otherwise fantastic sounding cheap and cheerful Hagerman MC stages. Is it enough noise to bother me? Nope. Doesn’t matter once the music starts.

If talking Hana Umami, the Red seems a little more electrically suited to Zero, due to its stronger magnet. I haven’t tried them yet, and can’t extrapolate beyond that. Even the Red is a little bit off of a Koetsu in its magnetic "efficiency" for this approach. But it’s close enough it could still be good.

A cool experiment would be to get hold of both versions of the Piccolo, since there is an older voltage drive version and compare them. So far as I know, the TI version may be nothing more than a current to voltage converter at the front end followed by the very same circuit downstream that adds gain in the voltage domain.

No, it’s just the Zero’s opamp doing the TI "magic". Nothing in common with the voltage-mode Piccolo (which is discrete JFET transistors, you can see the 4 metal cans), from what I can tell. I’ve had a few different voltage mode Piccolos, including the one built into Trumpet Reference. They also sound very good, but less like a SUT.

Quadratic SUT 

I spoke with the MC-1’s designer once, and he advised lifting VTA slightly to counteract this.

This disqualifies this designer for me because there is only one correct VTA position. To use VTA as a tone control is wrong, and could well result in record groove damage - particularly with modern stylus profiles which are very close to the cutter head in shape.

Once the current has been converted to voltage, the signal must be handled as voltage because all the downstream components are voltage driven. That’s why I suggested that the Piccolo Zero might be identical to the original Piccolo, after current is converted to voltage at the input. If you own both, check the innards of the Zero compared to the original Piccolo.

and what do you mean by “magnetic efficiency “?