[declancd7q]

Has anyone matched the BP20/25 pre with the new MPS-2 power supply?

I cannot get details whether it's compatible in Australia - is there any modiciation or additional hardware required?

[James Tanner]

Hi,

Yes you can use the new MPS-2 power supply with the older BP20 or BP25.

You just need a special power cable from the MPS-2 to the BP20/25.


james

[BachToRock]

James... I thought the seperate power supply on the earlier units just housed the transformer?  Does the new power supply not house a number of the electronics that were previously INSIDE the BP-20/25?

[Mike Pickett]

Hello;

The original BP20/25 power supply contained only a transformer, and the preamp itself handled the rectifying, filtering, and regulation of the power.  When we switched to the MPS-1 power supply, we moved the rectifiers into the power supply and added two stages of filtering.  However, we didn't actually remove any of the filtering or isolation circuitry from the preamp.  This is partly because you can never have too much filtering in a preamp supply, and partly to allow the preamp to be plugged into the older AC supplies (intentionally or accidentally) without blowing anything up.

The MPS-2 continues this practice, adding more current, more filtering and better over-current protection to the power supply, and leaving the preamp's internal isolation and filtering circuitry intact.  This allows the MPS-2 to remain compatible with older preamps without requiring modification of the preamp.

The only exception to this is the earliest BP-20's having a power switch on the front panel (where the Mute switch currently resides).  These preamps are designed to switch AC internally, and are not compatible with either the MPS-1 or MPS-2 power supplies.

Thanks,

Mike

[nicolasb]

In the interests of completeness.... So far as I can make out the BP25 with an MPS-2 is pretty much identical to a BP26, with one exception: if you buy the DAC upgrade, the BP26 allows you to power the DAC direct from the MPS-2 and independently of the preamp power supply, while the BP25 DAC draws power from inside the preamp. I've no idea how much difference this makes in practice.

[Mike Pickett]

Hi;

Nicolasb; you are correct.  The one major difference I forgot to mention with the MPS-2 was the addition of a dedicated low voltage supply, allowing us to reserve the high voltage rails for analog audio only.  In the case of a DA equipped preamp this makes a significant difference, since the DA converter and associated circuitry draw a lot of current at low voltage.  Tapping this low voltage supply from the high voltage analog rails works, but a dedicated supply is the preferred way to do it.

The BP26 is able to utilize this dedicated low voltage supply, while the BP25 requires significant modification to allow it.  However, this doesn't mean that a stock BP25 DA won't benefit from a power supply upgrade.  A BP26 just benefits 'more'.

Mike

[declancd7q]

Thanks all - this is a satisfying response as it verifies some observations that the BP20/25 doesn't sound appreciably different with the MPS-2.