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BK Components Pro 10 MC

Stereo Pre Amplifier

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BK Components Pro 10 MC


Frequency response: 1Hz to 150kHz

Total harmonic distortion: 0.2%

Input sensitivity: 0.09mV (MC), 0.8mV (MM), 45mV (line)

Signal to noise ratio: 70dB (MC), 82dB (MM), 89dB (line)



re: Pro 10 MC

I need the external power supply for the pro 10mc or a replacement one. Does anyone have one they want to sell?


re: Pro 10 MC

Does anyone have a service manual for this preamp? Mine needs work!

re: Pro 10 MC

Log to HIFI Engine, create an account and search the library. there is a downloadable owners maual

re: Pro 10 MC

Hey Jimmy
Never seen a service manual for this preamp but its a real simple design. What kind of problems are you having with it? I have one of these also that I use for my bench pre-amp since it has balanced outputs and a flexible phono stage it can integrate with just about anything.

re: Pro 10 MC

Hi bryrohr,

I am looking for a service manual for the Pro10, not the Pro10 MC.

I have two issues.
1. The in-line power supply has only +12 voltage, no -12 volts. I was thinking of just replacing all the components but it would be tricky to find parts small enough for the box and I don't know the componet values. It could be the transformer and I guess I could find a small 24V ct xfmr. The diodes test OK. I am loath to dismantle it unless I have access to the parts (transformer, mainly).

2. This pre-amp was working fine before the power supply issue. However, the balance control didn't seem to null the opposing channel output when rotated fully in either direction. I don't know if this is a design choice or a problem. I saw a similar query on some other site or Facebook page.

I have a cobbled-together system that works well for me. I needed more inputs than the B&K had, but with the addition of a smart TV, a modern DVD player and a Marantz DP-870 as a hub for my digital inputs, I am fine with this unit. The phono stage seems excellent. The Pro5 has more inputs and looks promising but funds are tight and handsome units are pricey. I am using a Yamaha receiver's pre-amp section in place of the Pro10.

My system:
Marantz DP-870
Yamaha receiver RX-V990 (pre-out only)
Kenwood KD-550 with Shure SA1
Pioneer RT-707
Pioneer CT-F1250
Sumo Charlie FM tuner
SSI system 3000 analog Dolby processor (VHS decoding and TV prior to digital broadcasts)
low end Toshiba DVD player
Samsung smart TV
Five Crown DC300A-Series II amps
three Emilar two-way front speakers (15" LF driver, bow tie horn)
Advent Legacy and Yamaha surround speakers

Only the TV and Advents were new. The others were being discarded or in need of repair.

Thank you.

re: Pro 10 MC

Hey Bill,

My pro 10 MC didn't have a power supply when I bought it second hand so I built one for it. Without dismantling the unit at this point, I seem to remember it simply being a + - DC power supply that was somewhere around +18vdc and -18vdc. The preamp has internal +/- 15vdc voltage regulators for both pos and neg supplies so the power supply input voltage was not at all critical as long as the input voltage to the unit does not exceed the max input voltage of the internal voltage regulators which for most voltage reg ICs is around 30-35 vdc. I think I used a center tapped transformer that was capable of 2000ma so there was plenty of current for the unit. I used a full wave rectifier and around 6800mfd capacitance per side so the incoming power was clean.
If memory serves me correct, the balance control does not completely mute either channel at the extremes but just provides adjustment.

Pro 10 MC

So you are sure the external power supply is a DC device with voltages around +18, -18 Volts DC,, that seem relatively easy to fabricate.. Any leads on the power plug that plugs into the Pro 10MC unit itself??? Do you have a pin-out as to what pins are negative and positive voltages??

re: Pro 10 MC

How about a p.s. for a MC-101? Thanks. Randy.

re: Pro 10 MC

Thanks for the reply, Bryrohr. As you can tell by the timing, this had not been priority.
I'm glad you mentioned the voltage regulation and the 18V transformer. I was going to look for a center tapped 12V xfmr. The value of the caps was a mystery also. I can work with this information.
A little story...
Years ago, I was called to a movie theater in Reno on a Friday evening. The 9VDC PS was dead and no spares on hand. I needed it to output 7VDC. It was used to light a special bulb that focused a slit of light on the soundtrack so the photo cell could produce a signal for the sound. I walked with the manager through the different booths and gathered parts together and built a PS on the floor behind the sound rack. I built the bridge and used a variac from a film rewinder to adjust the voltage. Monday I showed up with the proper PS. When I walked into the lobby, I heard the manager call out, "Hey, Magyver's here."
Thank you for the information. I never owned a piece of gear with the balance control not nulling the channel. Good to know. Thanks again.


I bought online an early version B&K Pro 10MC, not the Sonata version: no balanced outs or headphone amp. Unit arrived with plastic case for external power supply badly crushed, with 2 resistors and 2 small cans(? what they are) bent quite a bit but not detached from board. I thought the whole thing was a goner, but amazingly it still plays with a great sound through a B&K 1430 amp. The 2 capacitors are labeled 50V 1000mF. The copper-covered transformer is small. The whole box measures about 5.5" x 2.5" x 1.5". The box is in pieces so need to do something to stabilize the board, or buy a new PS. The AC cord and the DC output cords are unshielded 14-16 Ga wire (like zip cord) and are permanently attached to the inline PS and preamp. I could buy an aluminum case to hold the board for about $40-$50 shipped, then have connections soldered to make the AC/DC connections (I am not a DIY person!). But this minimum cost fix would leave me with bent components in a switching PS with 20 yr old components. I am liking as an alternative one of the many chinese made LPSUs available on eBay., but don't know the right specs to get. Basically the choices are 25VA Talema toroidal transformer units with max output voltage 18-24V/1.5A at about $80 shipped, or 50VA toroidal transformer with 18-24V/2.0A at about $120 shipped (advertised as "very low noise" vs cheaper 50VA units at about $90). These LPSU are wired for separate (upgradeable) power cord and include a detachable shielded DC output plug type cord. I would greatly appreciate any advice on these 2 options and any specific guidance on transformer size and output voltage/amp ratings. I am also not sure what is best way to get the DC cord plug connected into the Pro10. Thanks for any help.


I got off my lazy a$$ and tore into my PS. I drew up a schematic and traced it out. I had one secondary winding open and when it was replaced I found that one 15V DC regulator was bad and the Caps were good as is the rectifier. It works well now. The parts were less than $30.


How about a p.s. for a MC-101?

This website is not affiliated with or sponsored by BK Components. To purchase Pro 10 MC spares or accessories, please contact the company via their website or visit an authorised retailer.