Balanced Preamplifier

[AP@1992]

Hello folks,

I have long been curious to try out preamplifiers in my system. Have heard some of preamplifier build by our FM and they were fabulous and a definite improvement in the existing sound quality. However I have certain queries which I wish to put forth for the forum to respond

1) are preamplifier with Balanced input same as inherently balanced preamplifier. That is to say any preamplifier which accepts a balanced input will have to be a balanced design ???

2) What if the chain from DAC to preamplifier is balanced, but the chain from Preamplifier to Speaker is SE, do you loose whatever, if any advantages that you may got in the previous transmission of signal uptill preamp.

3) Are balanced devices/transmission only relevant for suppressing noise, or is there any other benefits (either device specific or in general)

Regards

 

[bornfi]

Hello folks,

I have long been curious to try out preamplifiers in my system. Have heard some of preamplifier build by our FM and they were fabulous and a definite improvement in the existing sound quality. However I have certain queries which I wish to put forth for the forum to respond

1) are preamplifier with Balanced input same as inherently balanced preamplifier. That is to say any preamplifier which accepts a balanced input will have to be a balanced design ???

2) What if the chain from DAC to preamplifier is balanced, but the chain from Preamplifier to Speaker is SE, do you loose whatever, if any advantages that you may got in the previous transmission of signal uptill preamp.

3) Are balanced devices/transmission only relevant for suppressing noise, or is there any other benefits (either device specific or in general)

Regards

To realize full potential, the chain end-to-end must be balanced, in my opinion.

 

[Yelamanchili manohar]

Hello folks,

I have long been curious to try out preamplifiers in my system. Have heard some of preamplifier build by our FM and they were fabulous and a definite improvement in the existing sound quality. However I have certain queries which I wish to put forth for the forum to respond

1) are preamplifier with Balanced input same as inherently balanced preamplifier. That is to say any preamplifier which accepts a balanced input will have to be a balanced design ???

2) What if the chain from DAC to preamplifier is balanced, but the chain from Preamplifier to Speaker is SE, do you loose whatever, if any advantages that you may got in the previous transmission of signal uptill preamp.

3) Are balanced devices/transmission only relevant for suppressing noise, or is there any other benefits (either device specific or in general)

Regards

Hi

1. Having XLR inputs or outputs is not necessarily a guarantee of a balanced design. To turn a single ended preamp into a balanced design, we have to exactly double the circuit, so that there is a independent circuit for each channel. More extreme designs even have independent power supplies for each channel. This almost doubles the cost.

2. A balanced design gives optimal results only when the entire chain is balanced. That is starting from a dual mono dac, to balanced preamp to balanced stereo power amp or mono block power amps, all connected via balanced XLR cables.

To be honest, the term balanced is a bit over rated. And is not necessarily required in a domestic setup with short runs. In recording studios and American homes with huge rooms, where components are connected at different wall sockets over large runs, there is a need for balanced circuits to avoid hum over those distances, and to maintain signal integrity.



In the above room, the entire source chain is at one end of the room, with the power amps placed next to the speakers. This necessitates a run of 15 to 20 feet of interconnects from the preamp to the power amps. Besides, the preamp and power amps are connected to different wall sockets. This requires balanced connections due to the 20 feet runs, and also due to potential ground loops due to slightly varying ground potentials at the different wall sockets, even though wired on the same ring main of the room. Luckily, our smaller Indian rooms are blessing in disguise.

I keep alternating my preamps sometimes, which alternates the chain from balanced to unbalanced, and there is more than a slight improvement in imaging when the entire chain is balanced. But if one is a tube lover, which both of us are, then best to stick to SE, as balanced connections kill the harmonics that we are trying to add via tubes. So I much prefer SE connection from a non balanced preamp to my tube mono blocks by RCA cables, than using the balanced preamp, and connecting to the amps via XLR.

To my ears, single ended connections with tube amps with zero negative feed back gives diffuse imaging, but a more enveloping romantic rich sound. In fact my new tube preamp which I will receive this summer, only has SE outputs and inputs. And if we look around, the ratio of SE to balanced tube preamps is almost 10:1, and above is the reason for the majority being single ended.

Having said the above, if one is looking for a more technically correct sound, with pin point imaging, tighter bass and a more detailed sound, then a fully balanced chain will be an improvement over a single ended one.

 

[AP@1992]

Hi

1. Having XLR inputs or outputs is not necessarily a guarantee of a balanced design. To turn a single ended preamp into a balanced design, we have to exactly double the circuit, so that there is a independent circuit for each channel. More extreme designs even have independent power supplies for each channel. This almost doubles the cost.

2. A balanced design gives optimal results only when the entire chain is balanced. That is starting from a dual mono dac, to balanced preamp to balanced stereo power amp or mono block power amps, all connected via balanced XLR cables.

To be honest, the term balanced is a bit over rated. And is not necessarily required in a domestic setup with short runs. In recording studios and American homes with huge rooms, where components are connected at different wall sockets over large runs, there is a need for balanced circuits to avoid hum over those distances, and to maintain signal integrity.

View attachment 84041

In the above room, the entire source chain is at one end of the room, with the power amps placed next to the speakers. This necessitates a run of 15 to 20 feet of interconnects from the preamp to the power amps. Besides, the preamp and power amps are connected to different wall sockets. This requires balanced connections due to the 20 feet runs, and also due to potential ground loops due to slightly varying ground potentials at the different wall sockets, even though wired on the same ring main of the room. Luckily, our smaller Indian rooms are blessing in disguise.

I keep alternating my preamps sometimes, which alternates the chain from balanced to unbalanced, and there is more than a slight improvement in imaging when the entire chain is balanced. But if one is a tube lover, which both of us are, then best to stick to SE, as balanced connections kill the harmonics that we are trying to add via tubes. So I much prefer SE connection from a non balanced preamp to my tube mono blocks by RCA cables, than using the balanced preamp, and connecting to the amps via XLR.

To my ears, single ended connections with tube amps with zero negative feed back gives diffuse imaging, but a more enveloping romantic rich sound. In fact my new tube preamp which I will receive this summer, only has SE outputs and inputs. And if we look around, the ratio of SE to balanced tube preamps is almost 10:1, and above is the reason for the majority being single ended.

Having said the above, if one is looking for a more technically correct sound, with pin point imaging, tighter bass and a more detailed sound, then a fully balanced chain will be an improvement over a single ended one.

This cleared a lot of my doubts and confusions. Thanks a lot !!

 

[keith_correa]

3) Are balanced devices/transmission only relevant for suppressing noise,

From what little I know: yes, a device' relevant circuitry to process a balanced signal input ONLY acts to remove environmental "noise" from the signal that MAY be induced external to that device' input.

or is there any other benefits (either device specific or in general)

No other benefit or for that matter no deterioration at all.

 

[Passive_audio_enthusiast]

From what little I know: yes, a device' relevant circuitry to process a balanced signal input ONLY acts to remove environmental "noise" from the signal that MAY be induced external to that device' input.

No other benefit or for that matter no deterioration at all.

Some time back I had the following chain - Topping D90LE -> Topping A90D -> T+A A1500. Everything in this chain is balanced. I went back to using my Chord mojo directly with the T+A(not balanced anymore). Again, I had a T+A PA1500R at home back then which didn’t had the balanced input the A1500 had. In all the cases, the mojo directly connected with the power amp sounded the best to me and I still use it that way. Don’t know if a higher end set of devices would benefit.

 

[Yelamanchili manohar]

Some time back I had the following chain - Topping D90LE -> Topping A90D -> T+A A1500. Everything in this chain is balanced. I went back to using my Chord mojo directly with the T+A(not balanced anymore). Again, I had a T+A PA1500R at home back then which didn’t had the balanced input the A1500 had. In all the cases, the mojo directly connected with the power amp sounded the best to me and I still use it that way. Don’t know if a higher end set of devices would benefit.

Thanks for sharing the above. I think whether dac direct to power amp or preamp to poweramp comes down to a matter a taste, and depends on what the preamp brings to the table. And whether that is preferred or not. In my case, apart from the need to cater to other sources, which anyways necessitated a preamp, I always preferred a preamp in the chain, as I felt it added body and dynamics to the mix. And as I said, in the end it is a matter of taste.

Having said the above, for my next project, I will be going dac direct to poweramp, as the dac apparently can be configured to have a 7 volts output, which theoretically should be sufficient to directly drive poweramps without sacrificing dynamics in the bargain.

 

[keith_correa]

... , as the dac apparently can be configured to have a 7 volts output, which theoretically should be sufficient to directly drive poweramps without sacrificing dynamics in the bargain.

7V RMS or peak? Which DAC is this, if I may ask?

 

[Passive_audio_enthusiast]

Thanks for sharing the above. I think whether dac direct to power amp or preamp to poweramp comes down to a matter a taste, and depends on what the preamp brings to the table. And whether that is preferred or not. In my case, apart from the need to cater to other sources, which anyways necessitated a preamp, I always preferred a preamp in the chain, as I felt it added body and dynamics to the mix. And as I said, in the end it is a matter of taste.

Having said the above, for my next project, I will be going dac direct to poweramp, as the dac apparently can be configured to have a 7 volts output, which theoretically should be sufficient to directly drive poweramps without sacrificing dynamics in the bargain.

Actually mojo is a device which works well as a preamp. It can output voltages to level of standalone preamps. I tried using Topping between chord and the T+A, somehow A90D was making the bass lean. I don’t miss using the Topping anymore as i didn’t feel they were an upgrade over the mojo which costs less than half of the combination. I couldn’t hear the extra cleanliness that topping stack was giving, given their better Sinad numbers. I think they both have noise level below audibility.

 

[Yelamanchili manohar]

7V RMS or peak? Which DAC is this, if I may ask?

7V RMS Sir...this is the OKTO Research Dac 8 pro. An 8 channel dac, with 7V output per each channel being an optional add-on, and is charged extra.

 

[AP@1992]

Thanks for sharing the above. I think whether dac direct to power amp or preamp to poweramp comes down to a matter a taste, and depends on what the preamp brings to the table. And whether that is preferred or not. In my case, apart from the need to cater to other sources, which anyways necessitated a preamp, I always preferred a preamp in the chain, as I felt it added body and dynamics to the mix. And as I said, in the end it is a matter of taste.

Having said the above, for my next project, I will be going dac direct to poweramp, as the dac apparently can be configured to have a 7 volts output, which theoretically should be sufficient to directly drive poweramps without sacrificing dynamics in the bargain.

My Weiss Minvera was (at highest analog gain stage read +17dbu) used to output solid 5.8V RMS. That was plenty sufficient to drive all and any power amplifier I had used. 7 Volt would theoretically obliterate the need to any preamplifier, save and expect preamplifiers with various tubes which will bend tonality in some way or the other.

Keep us posted on your next project.

 

[Yelamanchili manohar]

My Weiss Minvera was (at highest analog gain stage read +17dbu) used to output solid 5.8V RMS. That was plenty sufficient to drive all and any power amplifier I had used. 7 Volt would theoretically obliterate the need to any preamplifier, save and expect preamplifiers with various tubes which will bend tonality in some way or the other.

Keep us posted on your next project.

Sure will post back on the progress as and when I get started, as Iam still in the gear acquisition stage at the moment