Balanced to Single Ended converter

[rajan-]

During the last few days of the end year shut down, I am finally getting down to building a quality Transformer (Jensen jt-11p-1) based Balanced to SE converter.

The plan is to make the converter do Balanced to SE (with a pot to reduce gain match). this way we can use the high voltage output (normally excess of 4v) on regular SE devices.

and use the same in reverse (SE to Balanced) I believe this is a technique used in certain pre-amps

some of my personal use cases include.

this can be used on balanced source (Tascam ADDA), that I can connect to SE Head phone amp as well as DIY Pre-amp
I can also use it to connect SE Preamp to Balanced / Bridged mono power amps

This is based on a Jensen input transformer, that can be configured in multiple ways.

So far, I did one channel to see how / if it works ok, and its been a success


next would be to finish second channel and install inside a cabinet

 

[Hari Iyer]

What are the turns ratio ?

 

[rajan-]

What are the turns ratio ?

1:1

 

[rajan-]

Both channels completed.
After successful testing with the head phone amp, moved it to the main speaker system. And called Agam for an inhouse performance

TV -> Tascam ADDA -> Balanced to SE converter -> Pre Amp -> Power Amps

My Amp Camps are Amps are connected in Parallel mono setup, puts out 8 watts with a higher damping factor than Bridged mono mode or Balanced mono mode.

Had to turn down the pre amp volume as input voltage has gone up.
Also had to reduce Sub Gain.

Staggering improvements in performance. The Dynamics and control have significantly gone up.


Next stage would be to change the dual gang volume pot in the transformer circuit to something better, Alps will be natural choice, unless I can get a stepped attenuator at a decent price.

Anyone who has a balanced Source should try this with (may be with a cheaper 1:1 input transformer) and see if it makes a difference to their system. IMHO its a low effort high return gear. and its easier to replace the transformer with a better one later.


the inspiration for this came from a few different places and requirements.
Linn Klimax, Decware, PreAmps with input transformers, pro audio gear / removing Humming

 

[Hari Iyer]

Both channels completed.
After successful testing with the head phone amp, moved it to the main speaker system. And called Agam for an inhouse performance

TV -> Tascam ADDA -> Balanced to SE converter -> Pre Amp -> Power Amps

My Amp Camps are Amps are connected in Parallel mono setup, puts out 8 watts with a higher damping factor than Bridged mono mode or Balanced mono mode.

Had to turn down the pre amp volume as input voltage has gone up.
Also had to reduce Sub Gain.

Staggering improvements in performance. The Dynamics and control have significantly gone up.


Next stage would be to change the dual gang volume pot in the transformer circuit to something better, Alps will be natural choice, unless I can get a stepped attenuator at a decent price.

Anyone who has a balanced Source should try this with (may be with a cheaper 1:1 input transformer) and see if it makes a difference to their system. IMHO its a low effort high return gear. and its easier to replace the transformer with a better one later.


the inspiration for this came from a few different places and requirements.
Linn Klimax, Decware, PreAmps with input transformers, pro audio gear / removing Humming

If you are using a volume pot, then go for a constant Impedance wiring, else your input impedance will keep changing based on the position of the wiper.

 

[rajan-]

Preamp is a DIY Cascode version of Pass Bride Of Zen (BOZ). Single ended
Power Amp: 2 x Amp camp amps
Ref: https://cdn.shopify.com/s/files/1/1006/5046/files/ACA_Monoblock_Operation_RevA.pdf

listening tests in different configuration chains.

Config 1:
TV -> Optical to Coax converter -> Tascam da3000 -> Preamp -> SE to XLR converter -> Power amps in XLR Balanced Bridged mode -> Horns
-> Behringer mixer - > REL Sub

also tried with the older Schiit Modi DAC, and frankly can't listen to it after using the da3000

Observation:
The Bass was so much better compared to the converter placed between DAC and preamp, possibly due to the power amps being in Balanced Bridged mode. I turned off the Sub completely, it was still enjoyable.

But it lacked the finesse of the below config


Config 2:
TV -> Optical to Coax converter -> Tascam da3000 -> XLR to SE converter -> Preamp -> Power amps in Parallel mono mode-> Horns
-> Behringer mixer - > REL Sub

Observation:
Incredible Dynamics,
Much easier to listen at lower levels
Really enjoyable delicate details, and the natural decay of delicate music is much clearer compared to earlier config
Lesser bass from the horns (compared to config 1)
Since I have the REL for the bass augmentation, this is not an issue, turned it back on and adjusted the mixer gain (minimal gain at mixer level)


There is a massive difference in the quality and dynamics (for the better) when the Dac's XLR outputs are used.

I need to find a balanced differential preamp to compare between end to end balanced connections and signal processing
Vs
the current chain, where Balanced is used for interconnects (yeah,.. at this point only between DAC and preamp) and a future SE to XLR converter between pre-amp and power amp. if I decide to go this way, I wont spend the money for Jensen input transformers, I will try this out with much much cheaper transformers or even cheaper opamp based converters (thanks to aliexpress) to understand the potential.

However, I was wondering why on earth I liked the Config 2 better than Config 1, and spent some time reading.

Single-ended vs balanced preamp

I recently asked Tom for advice configuring a balanced preamp build, and he suggested a single-ended design with one or more universal buffers for balanced inputs and outputs: I personally don’t see a point of making a fully balanced preamp. You can get the same or better performance if you...

ncforo.com

response 3 gives a lot of information on SE advantages on Signal processing compared balanced/differential processing.


I need to finish this before moving on to DSP based room correction
Sooo many project ideas, not enough free time..

Anyone using Balanced DAC and preamps ? even better would be amp camp amp user with balanced bridged connections ? anyone here ?
@Subbu68 ?