Quicksilver conversion

lpd · 29th February 2008, 08:16 PM

How does this conversion form 8417's to 6550/KT88's look?

conversion

Original Burnedfingers · 1st March 2008, 05:06 PM

It looks good

I've converted 1/2 dozen of them so far.

I would also modify the bias to allow for individual tube adjustment.

lpd · 3rd March 2008, 03:10 AM

I thinking of converting a pair of Bogen MO-100A's to KT-88's. Four per channel, rebuild the front end, individual bias pots for each tube, triode/ultra linear switch.

Looks like a great candidate for medium power tube amp? Here's the schematic. Any thoughts?

Schematic

Original Burnedfingers · 3rd March 2008, 10:32 AM

Commercial 70 volt power amplifiers aren't really known for their low end so I wouldn't expect too much there. Actually it will run 6550's or KT88's the way it is. I have heard Bogans that people have just popped in some different output tubes and they sounded ok. I would loose the input transformer and the music/speech switch if it were me. If you wanted you could copy the Quicksilver which would allow you to use the easier found front end tubes.

The 8417 Quicksilvers will also work fine without changing the front end. A bias upgrade however I would highly recommend.

lpd · 3rd March 2008, 03:11 PM

What about the MO-100's? Look identical to the Quicksilver 8714 mono blocks to me or very close. I have access to a pair of these as well. I'm thinking of using the utility 9 pin socket for another stage of gain. These use 6550's of coarse, but look very similar to the Quickies.

shematic

Original Burnedfingers · 4th March 2008, 10:38 AM

Why do you need another stage of gain on the MO-100?

I like the MO-100A chassis the best and it is fine with small modifications. Change the bias circuit and loose the speach/music switch and the input transformer.

29th February 2008, 08:16 PM	#1
lpd diyAudio Member Join Date: Nov 2003 Location: BC	Quicksilver conversion How does this conversion form 8417's to 6550/KT88's look? conversion

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1st March 2008, 05:06 PM	#2
Original Burnedfingers diyAudio Member Join Date: Nov 2002	It looks good I've converted 1/2 dozen of them so far. I would also modify the bias to allow for individual tube adjustment.

3rd March 2008, 03:10 AM	#3
lpd diyAudio Member Join Date: Nov 2003 Location: BC	I thinking of converting a pair of Bogen MO-100A's to KT-88's. Four per channel, rebuild the front end, individual bias pots for each tube, triode/ultra linear switch. Looks like a great candidate for medium power tube amp? Here's the schematic. Any thoughts? Schematic

3rd March 2008, 10:32 AM	#4
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Commercial 70 volt power amplifiers aren't really known for their low end so I wouldn't expect too much there. Actually it will run 6550's or KT88's the way it is. I have heard Bogans that people have just popped in some different output tubes and they sounded ok. I would loose the input transformer and the music/speech switch if it were me. If you wanted you could copy the Quicksilver which would allow you to use the easier found front end tubes. The 8417 Quicksilvers will also work fine without changing the front end. A bias upgrade however I would highly recommend.

3rd March 2008, 03:11 PM	#5
lpd diyAudio Member Join Date: Nov 2003 Location: BC	What about the MO-100's? Look identical to the Quicksilver 8714 mono blocks to me or very close. I have access to a pair of these as well. I'm thinking of using the utility 9 pin socket for another stage of gain. These use 6550's of coarse, but look very similar to the Quickies. shematic

4th March 2008, 10:38 AM	#6
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Why do you need another stage of gain on the MO-100? I like the MO-100A chassis the best and it is fine with small modifications. Change the bias circuit and loose the speach/music switch and the input transformer.

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