[James Tanner]

As the power supply on the BP-26 is external ("The power transformer is mounted externally to eliminate power-supply noise interference"), is that not for a 'Performance' difference versus an 'Application' difference compared to the other Bryston preamplifiers?
 
Steve

Hi Steve,

Not really - if you shield the transformer properly in the products with internal transformers you can get the noise figures very close.  In fact we actually hand tune all the internal transformers by twisting them and looking on the scope for the null point. 

james

[srb]

Hi Steve,

Not really - if you shield the transformer properly in the products with internal transformers you can get the noise figures very close.  In fact we actually hand tune all the internal transformers by twisting them and looking on the scope for the null point.

James,
 
Not trying to be argumentative, but then why go to the (considerable) extra expense for the MPS-2?  Why not just use a properly shielded and hand tuned internal transformer in the BP-26?  It still seems to me that Bryston must have determined that there is some audible performance advantage, even if it's not proportional to the extra cost?
 
Steve

[SoundGame]

Here's my theory and only my theory - James can confirm or dismiss it - no harm intended:

My understanding is that the BP6 leverages the B60 preamp - 100%.  It appears that way even from the circuit board diagrams.  So in the production line - if it's a B60, it gets an extra power supply and gets the additional jacks to make it an integrated - if it's a BP6, it stays a BP6 down the line but at some point the B60 and BP6 are identical.  So there are clearly cost efficiencies here - the volume of B60's helps reduce the overall average unit cost of the BP6 - making it a lower cost / unit preamp and given what I perceive are Bryston's cost+profit philosophies - result in a lower cost to the client.

This though is not the same for the BP26.  The BP26 is a specialized design - with differences from the BP6 to move the power supply out.  It's laid out differently inside and has XLR.  So the boards / build are not common.  No additional cost efficiencies to be leveraged across other models.

The BP26 has the MPS-2 not for lower noise but for future use - such as utilzing with Bryston's upcoming headphone amp or other Bryston components that can leverage the external power supply.

It could very well be the the MPS-2 can provide more power and more consistently on a high-draw but such power demands are not the case for the Bryston preamps - so this becomes a mut point in the real world.

Just my own theory.

[James Tanner]

James,
 
Not trying to be argumentative, but then why go to the (considerable) extra expense for the MPS-2?  Why not just use a properly shielded and hand tuned internal transformer in the BP-26?  It still seems to me that Bryston must have determined that there is some audible performance advantage, even if it's not proportional to the extra cost?
 
Steve

Hi Steve

The idea with the MPS-2 was to provide a power supply that was much larger than could be put in the same one rack space chassis with all the other circuitry required and more flexibility in the future with other Bryston components. So for instance the BP26 can have an internal DAC installed or a Moving Magnet Phone stage or a Moving Coil stage internally without compromising performance.

We could have just had a simply box like in the BP-25 power supply but we also wanted to provide a method to allow other components to be hooked up using the same power supply so customers did not have to buy another power supply with other Bryston products. So far only the 10B electronic crossover and the MC Phono stage can also be plugged into the MPS-2 and soon the BHA-1 headphone amp as well. The original plan was to allow the CD Player as well but that did not work out.

Lastly we felt the cosmetically matching power supply was a much better look.

james

[SoundGame]

James - how does the output voltage/power and noise levels of the internal power supply of the BP6 compare to the external MPS-1 power supply of the BP25.  I see specifications on the MPS-1 but not on the BP6 (obviously because it's power supply is integrated); however, on your bench test you must have specs that the BP6 power supply must pass.

MPS-1 is: +/- 28V @ 350 mA and 56V @ 700mA.

The question really is whether the power supply within the BP6 actually meets or exceeds the MPS-1, ignoring the potential for some minor added noise of having the supply integrated in the BP6 box.

I'm not sure if the manufacturer / supplier of the BP6 power supply is different than the one for the MPS-1 and whether the BP6 actually has power supply "evolution". 

If Bryston philosophy is to hold up - I would think the BP6 should not be outperformed by an older model i.e. BP25.  Please confirm.  Thanks.

[vegasdave]

Good question! I would like to know too.

[James Tanner]

James - how does the output voltage/power and noise levels of the internal power supply of the BP6 compare to the external MPS-1 power supply of the BP25.  I see specifications on the MPS-1 but not on the BP6 (obviously because it's power supply is integrated); however, on your bench test you must have specs that the BP6 power supply must pass.

MPS-1 is: +/- 28V @ 350 mA and 56V @ 700mA.

The question really is whether the power supply within the BP6 actually meets or exceeds the MPS-1, ignoring the potential for some minor added noise of having the supply integrated in the BP6 box.

I'm not sure if the manufacturer / supplier of the BP6 power supply is different than the one for the MPS-1 and whether the BP6 actually has power supply "evolution". 

If Bryston philosophy is to hold up - I would think the BP6 should not be outperformed by an older model i.e. BP25.  Please confirm.  Thanks.

I will get engineering on that one

james

[vegasdave]

I will get engineering on that one

james

Sounds good.

[SoundGame]

I will get engineering on that one

james

Thanks James - much appreciated.  Sorry - but inquiring minds want to know....can't get enough.

[SoundGame]

I will get engineering on that one

james

Not to rush - really, but didn't want this one to drop off the radar - I'm sure you've got it.

[James Tanner]

Not to rush - really, but didn't want this one to drop off the radar - I'm sure you've got it.

Hi - today is a holiday in Ontario.

james

[SoundGame]

BUMP.  James - just following on the question regarding the BP6 power supply specifications vs. the MPS-1.

[SoundGame]

I will get engineering on that one

james

 

[SoundGame]

I will get engineering on that one

james

Hi James - I'm not sure if this got stuck in engineering but would still be curious to what the answer is - if it's available.  Thanks.

[SoundGame]

RECAP:
James - how does the output voltage/power and noise levels of the internal power supply of the BP6 compare to the external MPS-1 power supply of the BP25.  I see specifications on the MPS-1 but not on the BP6 (obviously because it's power supply is integrated); however, on your bench test you must have specs that the BP6 power supply must pass.

MPS-1 is: +/- 28V @ 350 mA and 56V @ 700mA.

The question really is whether the power supply within the BP6 actually meets or exceeds the MPS-1, ignoring the potential for some minor added noise of having the supply integrated in the BP6 box.

I'm not sure if the manufacturer / supplier of the BP6 power supply is different than the one for the MPS-1 and whether the BP6 actually has power supply "evolution". 

If Bryston philosophy is to hold up - I would think the BP6 should not be outperformed by an older model i.e. BP25.  Please confirm.  Thanks.
-----------------------------------------------------------------------------
I will get engineering on that one

james
_______________________________________ ____________________________

Any news on this?  Thanks!

[James Tanner]

RECAP:
James - how does the output voltage/power and noise levels of the internal power supply of the BP6 compare to the external MPS-1 power supply of the BP25.  I see specifications on the MPS-1 but not on the BP6 (obviously because it's power supply is integrated); however, on your bench test you must have specs that the BP6 power supply must pass.

MPS-1 is: +/- 28V @ 350 mA and 56V @ 700mA.

The question really is whether the power supply within the BP6 actually meets or exceeds the MPS-1, ignoring the potential for some minor added noise of having the supply integrated in the BP6 box.

I'm not sure if the manufacturer / supplier of the BP6 power supply is different than the one for the MPS-1 and whether the BP6 actually has power supply "evolution". 

If Bryston philosophy is to hold up - I would think the BP6 should not be outperformed by an older model i.e. BP25.  Please confirm.  Thanks.
-----------------------------------------------------------------------------
I will get engineering on that one

james
_______________________________________ ____________________________

Any news on this?  Thanks!

Hi James;
 
The BP6 actually uses the MPS1 transformer, and the same filter caps, as it's internal power supply.  It doesn't have the pi filter used in the MPS1, but is very much the same otherwise.
 
The advantage to the MPS1 is that it's external, otherwise, it's the same.

Mike

[SoundGame]

Thanks James - much appreciated.  Now I can sleep at night....just kidding.

I've just been curious about this but this answers the question.  Now, I'll need to research what a pi filter is.  Interesting.

[ian.ameline]

pi filter info;


http://my.integritynet.com.au/purdic/lowpass.html

[SoundGame]

pi filter info;


http://my.integritynet.com.au/purdic/lowpass.html

Okay - perhaps someone can dummy this explaination down a bit from me - what impact (if any) would the absence of a pi filter in a preamp power supply have?  I'm thinking in the case of the BP6, not much if anything (interpreting Mike P. comments), otherwise Bryston would have included it - since the philosophy is to build the best.