|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
76.190.189.117
Does anyone know a manufacturer of phono cartridges who is planning on building a truly balanced product?
Yes,I know that the phono cartridge set-up is "balanced",but it is not truly differential.
I mean a cart with 6 pins,and possibly having the grounds come off the windings.Even possibly allowing standard or true-balanced hook-up to the phono stage.
Thanks for looking and venturing your thoughts.
Tom:cat
Follow Ups:
A cartridge is true balanced. In a "true" balanced circuit there is no ground reference for the signal. Ground is strictly for shielding. What you propose is basically two unbalanced signals 180 deg out of phase.
See this post by Ralph Karsten. This may help you to understand.
Dan Santoni
+1
Phil
I think the confusion can be caused by a lack of understanding of the difference between "balanced connections" and "balanced differential circuits".What we are concerned with here is "balanced connections".
The advantages of balanced differential circuits are well documented and require a balanced source with a balanced connection from that source but we don't need a balanced differential circuit to take advantage of a balanced connection.
As you say, "A cartridge is [a] true balanced [source]".
If we have a single ended circuit with a SUT in front of it, we are afforded the opportunity to use a balanced connection and that will give us CMR that will cancel any noise picked up by the cable.
My point is, we don't need a balanced differential circuit to have a balanced connection and the CMR that it affords.
And a phono cartridge is balanced, so is the primary of a SUT.
With the simple addition of 2 wire shielded cables, the balanced connection CMR is there for the taking.
Just to be clear, in this case CMR is the only advantage of the balanced connection.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 09/29/15
The advantage of balanced lines is less noise.CMR of all noise picked up in the line.
So balanced lines are not about sound quality per se, just lower noise and lower hum.
BTW I have never heard the term "true-balanced hook-up". What I show above is a balanced connection.
A differential balanced connection is different but has, as far as I know, no advantage in terms of CMR.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 09/29/15
I am not going to argue up or down whether a balanced phono input is advantageous or not, but I agree with the rest of John's post; this is not something to worry about. If your phono stage has a balanced input, and if you hook up the cartridge using proper balanced cabling, you're done. (Attach the cable ground to the phono chassis, if it makes you feel good.) Then forgeddaboudit.I've been using an Atma-sphere MP1 (balanced differential input) phono stage for more than a decade. It's configured just as John described. Whether it intrinsically sounds better than an SE phono stage, of which I also own a few, I would not say, but for sure there's no hum ever, no matter how you ground it.
Edits: 09/29/15
I'm currently using a balanced differential configuration with the new Doshi 3.0 phono, specially designed Transparent Gen. 5 phono (by Josh and Nick) and the Atlas cartridge. (Using the normal RCA jacks on the Classic Direct). Among the advantages over the SE configuration are a much lower noise floor (something the Doshi excels in) as well as better dynamics. It's a big step towards sounding much closer to the sound of 15ips tape.
Myles B. Astor
Best explanation. See post. #3www.audioshark.org/all-things-analog-21/balanced-phono-stages-input-output-7819.html
Myles
Myles B. Astor
Edits: 10/01/15
I tend to think that of my Atma MP1, but saying it on this thread might have led to a sort of controversy that I usually (but not always, I admit) seek to avoid. Further, because the Atma is one preamp, and my other SE phono stages are different from it in many ways other than the balanced configuration, it is impossible to know exactly why the Atma seems quietest and most dynamic.
The Classic Direct tt has RCA outputs? How do you rig them for balanced? If the ground side of the RCA plug is wired as is often typical for SE, where the ground is a shield around a single central "hot" conductor, you could do better to add a second conductor identical to the hot conductor, which could be wired to the ground side of the RCA. Or, replace the RCAs with XLRs. I am sure you know all this, just saying.
I believe if you use a phono stage with balanced differential inputs and you use balanced cables from the cartridge, you will achieve the same result as having a fully balanced cartridge with centered tapped coils. I don't think it's necessary to have three wires from each cartridge coil because there would be no current flowing in the ground wire. For example, suppose you are using a low-output moving coil cartridge designed to be terminated with 100-ohms and your differential input had a 50-ohm resistor on each leg with one end of each resistor tied to ground, I believe that would work just as well as a fully balanced phono cartridge.
On the other hand, it might not make any difference if the input to your phono stage is unbalanced. My system is fully balanced from the output of the phono stage to the input of the power amplifier and it works just fine. I can't imagine how performance could be improved with a balanced input on my phono stage. What do you think would be the advantage of a balanced input to the phono stage?
Best regards,
John Elison
"What do you think would be the advantage of a balanced input to the phono stage?"If the phono stage has a balanced input (or SUT input), then the only advantage would be the CMR of all noise picked up by the cabling between the tonearm and the phono stage. Nothing more.
If the phono stage had balanced circuits all the way through then we have many advantages. Two of them would be the constant current draw and the power supply ripple rejection. There would also be the cancelling of any even ordered harmonic distortion created within the differential stage.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 09/29/15
I have my toearm wires configured for balanced operation and my phono has a balanced input.
But,after talking to two large equiptment manufacturers,I had to pose this question.As a balanced differential circuit is referenced to ground and the differential mode noise rejection is the difference beteween said connections.It is not "truly" balanced,as it does not have a ground,other than supplying a "ground" via the turntable/tonearm ground.
So yes,it does have the positive/negative portions of the soundwave provided by the transducer,but there is no ground on a phono cartridge.Only in and out of phase connections.
So without the fifth and sixth connections for ground,it is quasi-balanced.
I believe Ralph/Atmasphere and I have the same wiring configuration on our tonearms,from discussions over at AudioGon on the subject of :how to" set-up for a balanced input.
This was just a question resulting from asking a manufacturer whether they were going to offer a balanced input on their phono stages-AYRE AND PASS.
Tom:cat
"As a balanced differential circuit is referenced to ground and the differential mode noise rejection is the difference beteween said connections. It is not "truly" balanced, as it does not have a ground..."I'm not really following you.
All I know is this, in the balanced connection I show, any noise picked up in the cable will not pass to the secondary of the SUT because any noise picked up by the cable will be common in the two wires and transformers only respond to the difference between the two ends of the primary winding.
Most balanced connections in a recording studio are just 2 wires carrying the signal, neither referenced to ground. Those would be the floating secondary of a small signal output transformer of one piece of gear connected to the floating primary of a small signal input transformer of the other piece of gear. The only thing in the cable that's grounded is the shield.
The same goes for microphones. For instance microphones (like a u47 or a sm57) use an output transformer. That output transformer secondary does not have a grounded CT. The secondary is not grounded in any way.
In the balanced connection between those microphones and the balanced input of the micpre, the only thing grounded is the shield of the cable.
The "signal" wires just connect the floating secondary of the output transformer to the floating primary of the input transformer.
So again, I don't understand what you mean by "truly" balanced.
What I have shown is as balanced as anything gets.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 09/29/15
For some reason, Pass Labs does not feel the need for balanced cartridge inputs on their phono stages. Nevertheless, my XOno is the quietest phono stage I've ever owned; it's basically noise free.
On the other hand, Ayre seems to feel balanced cartridge inputs are desirable for their phono stage. I don't know how the two compare with each other.
Best regards,
John Elison
Hi Tidycat,
I believe there was a version of the GE RPX which was low impedance and balanced for radio studios.
I would guess that you could use nearly any MC cartridge differential. I know some MM cartridges connect the return of one channel to the cartridge shield. I don't know if that is the case for MCs. In any case you should be able to sever the connection and run either type differential. Ground the cartridge shield to the arm. It may be a chalange to find shielded balanced cable with low enough capacitance for MM carts.
Phil
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: