Hi,
This thread is a more common thought but since I'm using papa's gear, l put in the Pass section.
I'm using a Threshold Fet 1 Series Two to drive a Hypex NC400 amp.
As the Hypex really likes a balanced signal, I built in a couple of Lundahl transformers to balnace the signal, which works fine.
Some time (in winter only), to have fun I connect my Mini Aleph with its balanced inputs.
I'm using the Threshold because it's a real fine sounding preamp, an its phono section is great.
I upgraded to a better pono stage, and the Threshold has plenty of switches which I'm not using and which certainly don't imrove the sound.
I want to change to some home made preamp, that's why we do DIY...
Some years ago I bought PCB's from KK of the Bosoz preamp which is a fully balanced design.
My DAC the new phono preamp have unbalanced outputs.
Is it preferrable to balance the signal with transformer to feed the Bosoz on both + and -, or connecting it a only one input (either + or -) would do the job?
When I see preamps with all inputs in balanced and unbalanced (and it is a throughout balanced design), how do they generally connect the unbalanced to the balanced input?
Sometimes I'm thinking to build the B1 and again put some Lundahl trannies, to make it easy. Didn't hear it though.
Thanks for advices!
- dan
This thread is a more common thought but since I'm using papa's gear, l put in the Pass section.
I'm using a Threshold Fet 1 Series Two to drive a Hypex NC400 amp.
As the Hypex really likes a balanced signal, I built in a couple of Lundahl transformers to balnace the signal, which works fine.
Some time (in winter only), to have fun I connect my Mini Aleph with its balanced inputs.
I'm using the Threshold because it's a real fine sounding preamp, an its phono section is great.
I upgraded to a better pono stage, and the Threshold has plenty of switches which I'm not using and which certainly don't imrove the sound.
I want to change to some home made preamp, that's why we do DIY...
Some years ago I bought PCB's from KK of the Bosoz preamp which is a fully balanced design.
My DAC the new phono preamp have unbalanced outputs.
Is it preferrable to balance the signal with transformer to feed the Bosoz on both + and -, or connecting it a only one input (either + or -) would do the job?
When I see preamps with all inputs in balanced and unbalanced (and it is a throughout balanced design), how do they generally connect the unbalanced to the balanced input?
Sometimes I'm thinking to build the B1 and again put some Lundahl trannies, to make it easy. Didn't hear it though.
Thanks for advices!
- dan
I tried it but the Hypex becomes noisy. It really likes balanced input, from a balanced signal.
Be careful not to conflate two separate issues. Balanced impedance signal interconnection is not the same thing as differential signal drive. Balanced interconnection is for the purpose of rejecting common-mode noise. Differential drive has to do with how the stage being driven best internally processes the signal given it. For example, the BOSOZ is best driven from a differential source due to certain aspects of it's internal circuit implementation. I don't know anything about the Hypex circuit, and so, cannot make a similar assessment about it.
In general, interconnecting unbalanced to balanced is a recipe for significant common-mode noise coupling. As you already know, the best performing means of interfacing unbalanced and balanced equipment without common-mode noise coupling is via audio signal transformers.
In general, interconnecting unbalanced to balanced is a recipe for significant common-mode noise coupling. As you already know, the best performing means of interfacing unbalanced and balanced equipment without common-mode noise coupling is via audio signal transformers.
Unbalanced to balanced
If I have a Bosoz (balanced) preamp, how should I connect my unbalanced DAC or Phonopre signal? Via a transformer (unbalanced to balanced), or to one of the positive/ negative input of the Bosoz?
If I have a Bosoz (balanced) preamp, how should I connect my unbalanced DAC or Phonopre signal? Via a transformer (unbalanced to balanced), or to one of the positive/ negative input of the Bosoz?
I prefer decent xformer , but you'll most likely get best result if you connect it to positive input on Bosoz , while grounding negative one to GND
so cable as :
RCA hot to pin 2 of XLR
RCA gnd to both pins 1 and 3 of XLR
again , xformer is better , but thinking of it without complete drive strategy is like opening completely new can of worms
so cable as :
RCA hot to pin 2 of XLR
RCA gnd to both pins 1 and 3 of XLR
again , xformer is better , but thinking of it without complete drive strategy is like opening completely new can of worms
Balanced is just a sub-set of differential inputs.
I would say the exact opposite!
While transformers are an excellent interface, they are not they only excellent method.
This is the sort of conflation I was warning of. Many amplifiers feature a differential input stage fed an unbalanced input. Typically, one half of the differential pair receives the input signal while the opposite half receives the feedback signal.
Differentially driven outputs and differential pair input stages are often confused with balanced impedance interconnection. Balanced impedance interconnection is for the purpose of common-mode noise rejection. Differential signaling is for other purposes, and doesn't have to provide common-mode rejection.
Single-ended drive (signaling) could be utilized over an balanced interconnection with the full benefit of balanced interface common-mode rejection. In short, signaling could be single-ended or differential, while interconnection could be balanced or unbalanced.
Please qualify why you would say that.
No, they certainly are not the only solution. For example, THAT! corp. op-amps feature patentd technology which greatly improves active device CMRR. Meanwhile passive transformers remain the best performing solution in terms of CMRR.
You can directly connect one of the BOSOZ's differential inputs to signal ground while connecting the opposite input to the unbalanced signal input. Nelson writes that it's possible to obtain better measured performance with unbalanced signals (although, not necessarily better subjective sound) by implementing the BOSOZ with an active current-source biasing tail, rather than via the passive resistor network biasing/gain tail of his original design.
Thanks. That's an answer I can live with
Basically it's the same that Hypex suggests when using their balanced input with an unbalanced preamp: put pin 3 to ground. I did this on my NC400, but there is a slight quality difference (but one can live with it).
Doing that I guess I will have the full advantage of the balanced output (-> going to a balanced input of the poweramp)?
- dan
Why do you want Balanced?
a.) Is it for the extra interference attenuation where the environment is very noisy?
b.) Is it for the extra voltage (+6dB) to drive the signals to the speaker a bit louder?
c.) Is it because the Receiver equipment has a Balanced Impedance input?
All three scenarios require slightly different solutions.
a.) requires a balanced impedance source driving balanced impedance cables. It's the balanced impedances and good quality cables that help reject the interference.
b.) requires an inverting stage to create the extra phase that gives the extra voltage. This could be added at the Receiver or at the Source.
c.) requires the addition of a balanced impedance output somewhere in the Source. The cheapest is a conversion cable, the next best is the addition of fig2.4 of Jensen's App Note an003
None of the above NEED a transformer. But option a. could benefit from adding a transformer at the Source instead of using electronically balanced active stages.
a.) Is it for the extra interference attenuation where the environment is very noisy?
b.) Is it for the extra voltage (+6dB) to drive the signals to the speaker a bit louder?
c.) Is it because the Receiver equipment has a Balanced Impedance input?
All three scenarios require slightly different solutions.
a.) requires a balanced impedance source driving balanced impedance cables. It's the balanced impedances and good quality cables that help reject the interference.
b.) requires an inverting stage to create the extra phase that gives the extra voltage. This could be added at the Receiver or at the Source.
c.) requires the addition of a balanced impedance output somewhere in the Source. The cheapest is a conversion cable, the next best is the addition of fig2.4 of Jensen's App Note an003
None of the above NEED a transformer. But option a. could benefit from adding a transformer at the Source instead of using electronically balanced active stages.
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