[tubesforever]

Poty,

I just wanted to clarify a few things so people know exactly what I am doing today.  I am using a modified Piccolo in its own case.  It was too noisy around the Hammond transformer when built into the C2 case work.  It functioned, but it never delivered the silence I require. 

I thought about building a Mu metal container but it would have been a great deal of work for uncertain results. 

My stand alone Piccolo in its Hammond case looks and sounds great.  It produces the quietness I need to hear.

The stereo cartridge is a balanced signal from what I have read in various posts by the late Garth Philippe of Incognito.   You can find these at the AudioAsylum vinyl board.

There is no common ground in a stereo cartridge.  It produces a purely differential positive and negative signal path of the right and left signal.  Grab the appropriate ground and you have an unadulterated balanced signal. 

I am running three eq settings on my C2 today and would never go back.  I simply turn down the volume when switching the cap value on my non shorting switch. 

I look forward to building a C3 when its available.

[poty]

...I am using a modified Piccolo in its own case.  It was too noisy around the Hammond transformer when built into the C2 case work.  It functioned, but it never delivered the silence I require. 

As you can see in my previous posts I want to divide both power supplies (Piccolo's and C2's - maybe even C3's) and put them into another case. So, in my layout there won't be any transformer nearby Piccolo's circuit. As soon as I'd like to build the PCB layout by himself it is obviuos thing to do to improve the sound.

My stand alone Piccolo in its Hammond case looks and sounds great.  It produces the quietness I need to hear.

For me it is not appropriate thing to do. You know, you lengthen the tiny signal path just because of another case. Second (not cheap I think) interconnect cable, spare pair of RCA connectors, outgoing and ingoing impedances... I think it is not good for the sound (but maybe it is good for the noise - who knows).

The stereo cartridge is a balanced signal from what I have read in various posts by the late Garth Philippe of Incognito.   You can find these at the AudioAsylum vinyl board.

There is no common ground in a stereo cartridge.  It produces a purely differential positive and negative signal path of the right and left signal.  Grab the appropriate ground and you have an unadulterated balanced signal. 

You never can grab the "appropriate ground" in case of a cartridge source you know, so you never can rid of the "common noise", so it is NOT balanced in any way. Every signal has positive and negative waves, but not every signal is balanced.

[tubesforever]

Perhaps you are confusing a balanced source from a balanced circuit?

A stereo cartridge is purely differential.   

A balanced amplification circuit cancels common noise in that particular circuit, but it does not and cannot cancel noise from the source. 

There is no common mode noise in a stereo cartridge.  Its a perfect source for a balanced circuit. 

 

[hagtech]

you lengthen the tiny signal path just because of another case

Path length is mostly a marketing panacea.  I would easily trade it for a reduction in hum or noise any day.  Everything is a compromise, there are no perfect answers. 

jh

[poty]

Perhaps you are confusing a balanced source from a balanced circuit?

I don't think so.

A stereo cartridge is purely differential.

Nope! Differential - meaning the wires carry signals of opposite polarity to each other in the relation with the common ground. In the cartridge there is NO common ground as I stated earlier.

A balanced amplification circuit cancels common noise in that particular circuit, but it does not and cannot cancel noise from the source.

Misunderstanding again. The "common noise" term refers to the disturbance, which equal to each "halves" of the signal path. Commonly the term is applied to the lines, not the circuits. And just this type of noise is cancelled by balanced circuits. It is external noise, not internal to circuits. As for internal noise - it is summed up from both "halves", so it is noisier again.

There is no common mode noise in a stereo cartridge.  Its a perfect source for a balanced circuit. 

So, a cartridge is not suitable for balanced usage. It is not balanced and connected with unbalanced line (so the impedances of the two connections is not the same - one of the conditions to eliminate line common noise).

Path length is mostly a marketing panacea.

Really? I always think just the opposite for the very small signals. And you proved it earlier, when do not agree to add some additional components to the signal path.

  I would easily trade it for a reduction in hum or noise any day.  Everything is a compromise, there are no perfect answers. 

I think you cheat the cause and effect (and there is no panacea). We all want to reduce hum and noise, but the ways to the nirvana destination is rather different. You can easily eliminate both emenies - just power off the audiosystem. You know - many of us won't do that. But if you make the sound worse and this way eliminate hum and noise - it would be the same as the powering off the system for the people involved.
Just one example - you connect Piccolo to Cornet and both of the devices have loading resistors, which is bad for the signal. If you have just one device - the cornet's is not necessary at all.

[Brinkman]

Nope! Differential - meaning the wires carry signals of opposite polarity to each other in the relation with the common ground. In the cartridge there is NO common ground as I stated earlier.

The cartridge signal is inherently differential - a differential signal that can be forced into balanced operation by the input circuitry of the pre amplifier. The pre amplifier provides the common mode voltage (pivot point), whereas before it was floating.

Whether or not this approach is "ideal" is more a philosophical question than I could answer, but I do know it is practical.

[poty]

The cartridge signal is inherently differential

Let's not speak without arguments. Just state a thing doesn't mean it is right. You can look at many sources, but the simplest way:
http://en.wikipedia.org/wiki/Differential_signaling
I'm Russian, so I don't know exactly which of English-speaking sources you trust more.

...a differential signal nothat can be forced into balanced operation by the input circuitry of the pre amplifier

Artificially you can do anything. And for some reasons now many things are practical, but in many ways they may be misleded (this time - marketing and ambitions).
As soon as the line (connection wires) from a turntable is not balanced (RCA forewer ) and the signal is not balanced as well you lose in the signal amplitude (you have to divide the signal to 2 to load both "wings" of a balanced preamp from the single source) and in the possibility to eliminate common noise (as I stated earlier-you need identical impedances of the source and the line and the input circuits).

[Brinkman]

Poty,

I applaud you for having the courage to step over the language barrier to argue your point. But I don't really see how your linked wiki entry is precluding the use of a phono cartridge for differential signaling. It seems to me that you have added your own preferred conditions to the terms balanced and differential that just aren't part of the real definitions.

In a MM cartridge, the four pins of a cartridge are each connected to their own respective pole of a pair of inductors. These four wires carry two complementary pairs, meeting the condition for Differential Signaling (2n wires, where n is the number of signals to be transmitted). Whether or not these pairs are treated as differential or single-ended (n+1 wires, where n is the number of signals to be transmitted plus one voltage reference) is dictated by the input circuitry of the pre-amp or if the "returns" of the turntable RCA cables are tied together at some point (2n becomes n+1).

As soon as the line (connection wires) from a turntable is not balanced (RCA forever) and the signal is not balanced as well you lose in the signal amplitude (you have to divide the signal to 2 to load both "wings" of a balanced preamp from the single source) and in the possibility to eliminate common noise (as I stated earlier-you need identical impedances of the source and the line and the input circuits).

You can see from my reasoning above how RCAs can transmit a differential signal, right? Whether or not a RCA cable is ideal for this application is beside the point.

Now, you're correct that balanced signal transmission requires identical impedances to some voltage reference (this is the pivot point for the see-saw). So you would agree that, in this manner, a single-ended input can benefit from the common noise rejection of a balanced circuit via the simple balancing of impedances to the reference voltage? In other words, the advantages of a balanced circuit are obtained regardless of whether the input signal was differential or single-ended.

Treating a single-ended or differential input to a single-ended circuit is a matter of shifting the pivot point to one extreme of the see-saw - by removing the impedance of one end to the common reference.

See this for an example of one channel of a phono pre-amp circuit that uses a differential input from a MC cartridge to drive a single-ended output (it's about halfway down the page). Look for this quote "One important detail to remember is that we have split the output signal from the phono cartridge, so each OpAmp only sees half the signal that one OpAmp would see in a conventional unbalanced configuration; since the OpAmps outputs are balanced, however, the total differential gain is twice as big; thus, no gain was lost in the amplification of the phono cartridge’s output signal."

This link is a detailed discussion Jim Hagerman participated in a while back on the topic we're discussing:
http://www.audiocircle.com/index.php?topic=38835.0

Thank you for bearing with me.

With respect,
Benjamin

[poty]

I applaud you for having the courage to step over the language barrier to argue your point.

I'm sorry if I look straightforward and maybe rather haughty. It's not intentions, it's just bad English. I have to write in short and very simple phrases.

But I don't really see how your linked wiki entry is precluding the use of a phono cartridge for differential signaling.

It's just good starting point for discussions.

It seems to me that you have added your own preferred conditions to the terms balanced and differential that just aren't part of the real definitions.

The terms are not interchangeable and means different things. Further you mix them freely and that way confuse things.

In a MM cartridge, the four pins of a cartridge are each connected to their own respective pole of a pair of inductors. These four wires carry two complementary pairs, meeting the condition for Differential Signaling (2n wires, where n is the number of signals to be transmitted). Whether or not these pairs are treated as differential or single-ended (n+1 wires, where n is the number of signals to be transmitted plus one voltage reference) is dictated by the input circuitry of the pre-amp or if the "returns" of the turntable RCA cables are tied together at some point (2n becomes n+1).

I think this is the main problem of your reasoning. The signal type is not relating to further circuits. So how it is treated further and how it is internally wired (and you know - not always there is a complementary pair of coils in a cartridge, for example - in MC cartridges) doesn't mean anything! It is presentation level, not interpretation.
There are single-ended and differential signals. If there are only two wires for a signal - it's single ended, if there are 4 wires bearing two identical signals (two wires for a signal, two of the wires represents the same "ground" mean point) of opposite polarity - it is differential. Otherwise every signal should be differential (or you can give me the example of pure single ended signal?).
It doesn't mean balanced or unbalanced circuits, further conversion (interpretation) or search artificial common ground. These questions are out of the scope of type of source signal. That fact Jim Hagerman tried to give with enough reasoning in the post you have pointed me to.
A cartridge have only two wires for each channel, so it is purely single ended.
Then... we will look at balanced circuit. In our case it consists of balanced line and balanced input. I'm repeating that balanced circuit doesn't directly related to differential signal. Their (balanced circuits) behaviour is the same for any type of source signal.
The main condition of balanced circuit is "horizontal symmetry". It means that both "halves" should have identical transmission characteristics in all respects.

You can see from my reasoning above how RCAs can transmit a differential signal, right? Whether or not a RCA cable is ideal for this application is beside the point.

Again, if we speak about balanced line it is not related to further circuits. The RCA-line is not symmetrical at all! It is coaxial. It means it have different impedances of each wire (connection). Line impedance is not input impedance of the amplifier you know! So, the noise inducted in the two wires has different characteristics and can not be treated as common noise. There is no common in the coaxial line.
If you change the coaxial line to the twisted-pair (for example) you get balanced connection.
The result - standard RCA-ended coaxial line is not suitable for common noise reduction at all. The connection (RCA) is used on most turntables. So...

Now, you're correct that balanced signal transmission requires identical impedances to some voltage reference (this is the pivot point for the see-saw). So you would agree that, in this manner, a single-ended input can benefit from the common noise rejection of a balanced circuit via the simple balancing of impedances to the reference voltage? In other words, the advantages of a balanced circuit are obtained regardless of whether the input signal was differential or single-ended.

Completely agree if we speak just about the balanced input. At that stage you can connect single ended or differential signal to the balanced input and have common noise reduction for both cases, but you should have balanced line connected!!! And as we agreed (I think) earlier, RCA is not balanced, so in that case you do not have this useful thing happend.
With great respect,
Vladislav

P.S. I'm very impressed of Jim Hagerman's understanding of the question we are discussing in the thread you have sent me. I'm completely agreed with his view of the question.

[poty]

After some thoughts and looking into the modifications which Bartas has done, I have some questions (most of them Bartas asked in the "Planing some serious Cornet tweaking" topic) about the Cornet 3 schema.
1. Are the current and voltage values mentionen in the schema valid (especially for the first two stages)?
2. Were the former (in the Cornet 2) R204 and R212 resistor dropped by intention, not mistake?
3. How about EQ circuits? I think there is a mistake, because 3k3-1nF circuit should be named as RIAA shurely (it is used in Cornet 2 in such values).

[slowburn]

Dug open my old notes for variable EQ.  The reference phono I've been working on for so many years (it keeps changing) had finally narrowed the EQ thing down to three positions (same as the Zanden folk).  All of the microgroove can fit nicely into these categories, only the 78's get out of range.

In the Cornet, C2, or C3, the second set of EQ is done using a 1nF capacitor.  This is what needs to change.  I re-did the calculations and came up with the three values needed:

1) Two 680pF in parallel : Columbia/NAB
2) One 1000pF : RIAA
3) One 680pF : ffrr/EMI

The problem is switching into position will cause a huge "tic" or "thump" in the output.  I thought of maybe keeping the unused positions charged up with a 1M bleeder, but this would only screw up EQ in the bass region.

I'll look at possibly switching in/out resistors instead.

jh

Dear Mr. Hagerman,

Any chance you'd also set aside a few alternative phono EQ values for the octal Cornet, which years later I still love?

Thanks again for the great design.

[hagtech]

The OCTAL uses EQ components pretty similar to the regular CORNET.  You could probably try switching in the values posted earlier in this thread.

jh

[gurevise]

Jim,
What's the gain of Cornet 3 ?
Will it work without input step -up transformer with high output MC cartridges (2...3 mV output) ?

Thanks
Sergey

[etcarroll]

Jim -

Any chance you may have a published spec for the Cornet 3 by Fall, as I have that time earmarked for a build.

Gene

I don't like this.  It's not about bleeding to ground.  You have to bleed to the signal path that's in action.  I don't want to put any extra parasitic RC time constants onto a live EQ.  Sorry, I'm a bit anal about that sort of thing.

If anything, it's a long time away.  I just can't get to it right now.  Can you imagine - I have a C3 board prototype mostly stuffed with parts - and it sits in a box.  It feels very ignored and abandoned.  Poor thing. 

jh

[hagtech]

Cornet 3 is on hold for the moment.  No idea when I can get back to it.  Same thing for the turntable controller.  I keep thinking I need to have prototypes ready by RMAF, but time flies...

jh

[analog97]

Cornet 3 is on hold for the moment.  No idea when I can get back to it.

Ah, drats!!  I do understand however.  Best wishes and hopefully the time constraints forced on you will lessen sooner than expected.