Bp-17 dac
 

Hello James - congratulations to the design team for the execution of the 17-cubed.

The BDA3 also receives fantastic reviews (and test measurements to confirm them)

How much commonality is there between the DAC board in the BP17-cubed and the BDA3?

Thanks!

Hi

They are similar in design.

The BP17 uses one stereo DAC whereas the BDA-3 uses separate DAC's for the left and right channels.

james

Would consider the pair of XLR inputs & outputs a pretty big deal on BP17 compared to the all single-ended on the B135. Is a nice feature for those of us with balanced headphone amps.

Hey all, new member - I've been eyeing the bp17 cubed for a while - but the other month I picked up a used BHA-1 FX (powered by the MPS-2) and while it works fine as a preamp right now, it got me thinking - "maybe I'm just better off going for the BP26". Any thoughts? The price would actually be about the same (maybe a bit cheaper overall for the BP26). Sure, it doesn't have some features (secondary balanced out or fixed level balanced out), but I don't know if I should kill myself worrying about that. I'm also under the impression that the signal path is summed internally for both preamps, so its not like my complete signal path from source to speaker would be balanced (of course correct me if this is inaccurate). I'm also under the impression that unless I have some real noise monsters, it may not matter.

Any thoughts would be appreciated.

greenpsycho... Welcome to AA! :wave:

Am wondering what you mean when you state "........signal path is summed internally......."? Believe there may only be one power supply, but not sure about "summed"....... Perhaps James could comment on that.

As you have the BHA-1 would think you (as I) would benefit from the 2nd set of XLR outs to run your headphones in balanced mode. Switching XLR cables from my BP-25 between the BHA-1 & 4B-ST is a pita.

Hi

I think what he means is that some products have 2 separate signal paths from input to output. So the positive half of the waveform and the negative half of the waveform have independent circuits throughout (which doubles the cost).

The only issue with this type of topology is the advantage of the Balanced inputs cancelling noise through common mode rejection is lost.

All Bryston XLR inputs and outputs are fully balanced differential discrete circuits so they take advantage of the noise cancelling of CMR but will have a single signal path (positive and negative signals combined) after the Balanced input till it reaches the Balanced output.

james

Right, typically, when I see a product state "fully balanced" its means its not summed internally (ie back to SE, and then back out to balanced - I am coming from the headphone world, so maybe its a bit different). It is my understanding that maintaining these separate signal paths is the ONLY way to maintain common mode noise rejection as you can't have a break in the chain, however, your statement makes me think I'm mixed up in this?

I believe the BHA-1 will convert SE input to balanced output (both XLR and front panel headphones), so thats a potential work around - outputting line level SE to the BHA-1.

Realistically, I need 3x outputs - 1x balanced preamp for my monitors, 1x preamp for another zone, and 1x balanced line level for my BHA-1. I'm using splitters and some other hacky fixes right now as I have my BHA-1 serve all these duties. I THINK the BP17 suites my needs more, I guess my question is are the qualitative differences enough that I should go for the "cheaper" BP26 and deal with the ergonomic shortcomings.

Thanks all!

Hi Folks,

Here's a little article I did on fully balanced circuits a while back.


Is Your System Out Of Balance

One question which keeps coming up over and over is the controversy regarding audio components being "fully balanced" versus what is sometimes referred to as "balanced converting to single ended" at the input of the electronic component (preamp, electronic crossover, amplifier etc).

The correct term for this balanced converting to single ended is more accurately referred to as "differential amplifier balancing" Popular mythology has seen fit to 'bless' the concept of 'fully-balanced' (meaning of course, two completely separate signal paths through a component, with its attendant doubling of parts cost and complexity, and halving of reliability). This approach completely misses the place, which is, of course too eliminate hum and noise picked up by the audio cables feeding the component.

The reason for this is that a differential amplifier rejects any common-mode noise which appears at its input, by a factor equal to its common-mode rejection ratio, (normally over 1000:1). A 'fully-balanced' circuit has a common-mode rejection ratio of precisely zero, since all signal, common-mode or not, is simply amplified and passed along via the two signal paths. It then remains up to the following component to attempt to reject that amplified noise, if it has a differential amplifier.

Thus, fully-balanced circuitry is subject to passing along any noise which might be picked up on all the cables. Then it hits the final component in the system, usually the power amp, where the differential amplifier at its input is left to deal with the sum total of the common mode noise in the signal path, (multiplied by all the gain in the system). I don't think this is an ideal scenario. If each component, (source, preamp, electronic crossover, power amp), had its own differential amplifier input, it would cancel any common-mode noise which appeared ahead of it, rather than amplifying it.

All the above simply points out that what has been called fully balanced circuitry has a host of disadvantages from cost to noise overload to complexity and reduction in reliability. It has no useful advantages in the digital or analog signal chain beyond the mic preamp.

Also remember the above supports no need for ‘Fully Balanced’ from a performance standpoint. The 7B, 14B and 28B's are fully balanced because they are designed as ‘SERIES’ amplifiers not because they have a performance advantage.

james

I'm convinced........... just ordered a BP-17cubed from Ivan.
Will put my BP-25 in the classifieds shortly.