Tube based phono preamp (tube rectification) with balanced inputs and outputs
- Thread starter sstalwar
- Start date
Huh? balanced lines increase gain by 6db while rejecting hum, its doesnt degrade the s/n.
The line does not degrade the signal-to-noise ratio, but connecting the differential signal to the balanced input of the RIAA preamp does.
Last edited:
FWIW that's an older MP-3 in the phono. For at least 5 years now they have dual outputs.
A second phono input is an option on it and the MP-1.
Also FWIW we were the first to use balanced connections for phono inputs worldwide and have a fully differential balanced phono section.
This statement is false if the connection supports the balanced standard known as AES48.
This statement is false. A balanced connection allows the receiver of the signal (in this case the phono input but could also be the connection between the balanced phono circuit and the line stage) to reject hum that is common to both inputs (inverting and non-inverting). So its more resistant to hum in this regard. If the circuit is differential, each stage of gain has up to 6dB less noise than the same circuit executed single-ended. This adds up from stage to stage and is why our balanced phono section, despite passive EQ, only has two gain stages yet can work with LOMC cartridges.
The relevance to home use is obvious to anyone who has auditioned interconnect cables and heard a difference.
One of the goals of the balanced line system is to eliminate interconnect cable colorations. Its quite good at this, hence most recordings made since the dawn of hifi, many made long before there was an 'exotic interconnect cable' industry.
If you like seeing your cable investment turn into a white elephant, by all means go single-ended. Someone else next year will have a better sounding cable. All the equipment in my system supports AES48; I never have to think about concerns with interconnect cables.
This statement is false. These are just words without any evidence. It is very easy to understand how 5 mV of a differential signal is converted into 2x2.5 mV of a balanced signal. Then simple arithmetic.
This is a disadvantage of balanced amplification, not balanced connection.
I will give an example of an excellent solution to a similar problem: Studer tape recorders also use balanced connections, but the signal from the magnetic head is amplified by CE amplifiers. Only at the output is an inverting amplifier used to obtain full balanced output.
These statements are entirely false. In a balanced line system the shield is ground. That is the tone arm tube.
Phono cartridges are balanced sources. The reason there is that weird ground wire that no other single-ended source seems to need is you have to do something about the shield: that's the ground wire.
The reason to go balanced is immunity from interconnect cable coloration (which is why there are some very expensive single-ended tone arm cables) and greater immunity to noise impinged on the cable. If there's any place in the entire system to get things right, its the front end of the system since no matter how good the preamp, amps and speakers are, they cannot make up for a loss or alteration of the signal before it even gets to the preamp!
so its a misunderstanding that tonearmcable should be short instead of SUT to riaa cable...the balanced cart signal can better drive long cables
Especially if its a LOMC, since their source impedance is so low driving the cables. You want to keep an SUT as close to the preamp input as you can and keep the interconnect cable capacitance down since that affects the SUT loading.
The signal from the cartridge is a differential signal. The tonearm does not participate in shaping the signal from the cartridge in any way.
The noise that gets on the cable is called hum. Theoretically, it should be less than in an unbalanced cable. But there is no practical difference in the length of the cable from the cartridge to the phono amplifier. Unless this cable is 10 meters long. Have you seen this?
You are right!
My mistake. MC cartridge is balanced, MM (as I read) need a modify.Something for me is not so clear, we use balanced connection to reduce noise in a short distance (most of all hifi sistem has got turntable very close to the phono preamp) but at the same time we use tube (insted solid state that have no hum) to amplifie a very low signal.
In the gold-era of vynil this connection wasn't practiced, i think.
If is so good why is not implemented in all arms and phono preamp?
Could be like use a gun to kill a fly?
Nearly all arms are balanced. You can run a balanced line from any Dual, Garrard or BSR turntable made in the 1960s or 70s; any arm that runs a separate ground wire. Its really about the phono preamp.You are right!
Something for me is not so clear, we use balanced connection to reduce noise in a short distance (most of all hifi sistem has got turntable very close to the phono preamp) but at the same time we use tube (insted solid state that have no hum) to amplifie a very low signal.
In the gold-era of vynil this connection wasn't practiced, i think.
If is so good why is not implemented in all arms and phono preamp?
Could be like use a gun to kill a fly?
Tradition is the main reason a balanced connection isn't used. In the 1950s when tubes were the only game in town they were just as expensive as they are today. So anything to keep cost down was practiced.
Even if the goal is to run a single-ended circuit, these days its not that hard or expensive to have a balanced/differential input even if the rest of the circuit is single ended.
Similar threads
 | Steve Williams Site Founder | Site Owner | Administrator |  | Ron Resnick Site Owner | Administrator |  | Julian (The Fixer) Website Build | Marketing Managersing |