I found a Threshold FET 9 preamp at a recycling center (!!!), no power supply. It's in fantastic shape and I have hooked it to a friends power supply and it works. Threshold power supplies are few and far between and not cheap. I would like to build my own. I could backwards engineer the original, or if anyone has a schematic for the original or if there are any plans floating around for an upgraded power supply, that might be a good way to go. It's 18 volts DC but I'm not sure of the amps or wattage required at the output as I can't find much on either unit. The power supply does have a sticker that notes input power select of 120 vac or 240 vac with a max drain of 10 watts. The fuse for 120 vac use is .5 amp, slow blow or 1/4 amp slow blow for 240 vac use.
Any suggestions would be appreciated.
Thanks,
Eric M.
Any suggestions would be appreciated.
Thanks,
Eric M.
This should do it. Test the diy supply with load resistors before hooking it up,
and especially for correct pinout in the connector.
Threshold Audio FET Nine - Manual - Stereo Pre Amplifier - HiFi Engine
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Thanks, just what I needed. I gotta use that site more often. It said I'd been a member for 2 years, 11 months but I couldn't even remember my log-in name. The FET 9e is much more elaborate that the FET 9. This should be a pretty simple build.
A question regarding transformers. I took the part # of the transformer 08 6/18 from the schematic (I think that's what it was, the copy is a little fuzzy) and did a search. What I came up with was a product from Newark that was exactly what I needed (see spec sheet link below)
http://www.farnell.com/datasheets/2...67.318893754.1549164618-2055694067.1549164618
But, I have no idea how I got from that first part number to this.
How do you even go about identifying a transformer like this - with 2 primaries and 2 secondaries?
Thanks,
Eric
A question regarding transformers. I took the part # of the transformer 08 6/18 from the schematic (I think that's what it was, the copy is a little fuzzy) and did a search. What I came up with was a product from Newark that was exactly what I needed (see spec sheet link below)
http://www.farnell.com/datasheets/2...67.318893754.1549164618-2055694067.1549164618
But, I have no idea how I got from that first part number to this.
How do you even go about identifying a transformer like this - with 2 primaries and 2 secondaries?
Thanks,
Eric
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On another note. Looking at the power supply schematic, the spec for the filter caps, C1 and C2 look to be 2100U /35V. That's gotta be 21000 UF, wouldn't you think?
Any issue with using a Bridge Rectifier (VBO36-16NO8) instead of the four IN4004 diodes?
Thanks,
Eric
Any issue with using a Bridge Rectifier (VBO36-16NO8) instead of the four IN4004 diodes?
Thanks,
Eric
> That's gotta be 21000 UF, wouldn't you think?
Its a preamp, not a power amp.
The current requirements are less than 1/10th of a power amp.
Logically the main caps can be 1/10th the size a power amp might use.
And then there is regulation after that.
Its a preamp, not a power amp.
The current requirements are less than 1/10th of a power amp.
Logically the main caps can be 1/10th the size a power amp might use.
And then there is regulation after that.
I have service manual
Here you are. I just built an outboard power supply for a B and K Pro10mc. 2 internal transformers. Let me know if you have any questions.
Pm me. The service manual exceeds upload size limit here.
I own this preamp too.
Rick
Here you are. I just built an outboard power supply for a B and K Pro10mc. 2 internal transformers. Let me know if you have any questions.
Pm me. The service manual exceeds upload size limit here.
I own this preamp too.
Rick
I opened the cover on my friends power supply. His 2 caps are 15,000. These can't be 2200 UF. The copy of the service manual looks like a scan you might have seen 20 years ago where the software converting to PDF has a hard time recognizing letters and numbers. I'm going to go with the 21,000 and check my voltage. The service manual calls for 20 - 29 volts no load. I'm assuming if I'm in that range I should be good especially since the unit has internal regulating. (I hope)
Eric
Thank you Rick. I'll put some questions together for you in a PM. Maybe your copy of the service manual is better than what I downloaded.
Where in CA are you?
Eric
I am in San Jose. The service manual has the transformer voltages. Dual primary dual secondary. Send me the pm
Hi Rick, thank you for you contribution to power supply information on this forum. I am also in San Jose and could use your assistance with a DIY B&K preamp power supply.
Sorry for bumping this thread with my personal issues. Unfortunately as a new forum member sending PM is disabled. Rick please send a PM and I will reply
Bump
Rickcl, I'm in the same boat as ddaarr was, account is too new and I can't send a DM. Mind DM'ing me your email address? Same boat as OP, going to pick up a Threshold 9e pre with no power supply and would like to assemble my own, depending on the difficulty.
Eric M, I'm curious how your build went for the Threshold.
Rickcl, I'm in the same boat as ddaarr was, account is too new and I can't send a DM. Mind DM'ing me your email address? Same boat as OP, going to pick up a Threshold 9e pre with no power supply and would like to assemble my own, depending on the difficulty.
Eric M, I'm curious how your build went for the Threshold.