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Vintage threads from the first ten years

Bogen PA question

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9/3/1999 5:35 AM
Cruiz	Bogen PA question Hi I was wondering if someone could suggest a substitute tube for a Bogen PA that uses 8417's? It works and sounds great know but I know these tubes are not the most common tube out there. Could I replace it with something like a EL-34 or a 6l6. Thanks in advance. Chris

9/3/1999 10:54 AM
Doug B	You could use a 6L6 typr tube, but you would have to rewire the socket and change the bias circuitry to provide a more negative bias voltage for the 6L6. The amp will produce less power unless the driver stage is extensively modified. Unless you are well versed in working on amps and high voltage I suggest you bring the amp to an experienced technician.

9/3/1999 2:59 PM
Graywater	Cruiz, First, the 8417 is long lived so you may not face the replacement issue for a while. Secondly, the 6550 makes a pretty good sub but requires more drive voltage. Ned Carlson has some great info on his Triode Electronics website (www.triodeel.com). I've got a couple of these amps and love 'em. Send me an e-mail if you want more infor. GW

9/4/1999 1:29 AM

I just picked up one of these at auction, but it's a model J330; uses two 6L6's. The former owner was very meticulous and saved all the paperwork, schematics, etc. If it is similar to the design of yours, aside from the power tubes, I could photocopy the schematic of this 6L6 version and mail it to you, if you think it would help. This piece is in great physical condition, still in the original Bogen box, but it threw a fuse about 30 seconds after firing it up. I suspect dried out caps, or something of that nature. Would it be wiser of me to restore it to original condition or attempt a multiple gain stage homebrew? I'd appreciate anyone's thoughts!

9/5/1999 3:49 PM
Fj	I built a JTM-45/PLEXI using the iron (OT & PT) from the same BOGEN amp!...very GOOD sounding...(here,s some pix of that amp...the 2 in the middle...) Frank. http://www.blast.net/fjr/Toaster.html

9/5/1999 6:19 PM
mosrite man	Sounds like a plan! This piece seems to be a good candidate for such a project, since it has so many holes in the chassis for input, knobs, etc. Plus it's built like a tank. BTW, love the graphics on your page!

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