Fisher X-101-B

[CWelsh]

I have an unrestored Fisher X-101-B that I've had lying around for over 20 years. I've hooked it up a couple of times and it does work, but I know next to nothing about vintage tube equipment and I'm always afraid I will set something wrong and break it, so I honestly don't know what kind of shape it is really in.

I've looked through the forums for posts on this model and found a few, but I would like to know a little more about this amp and get some opinions on what I might have to invest to fully restore it and whether it is worth it or not. I know that final question is very subjective, but I see several Fisher fans here who I hope can help me decide what is right for me.

Thanks, and I look forward to hearing from you all.

 

[Jailtime]

Your X-101-B is a very nice 7591 based amp. Fisher integrated amps have great transformers. It is absolutely worth restoring, look to spend about $150 for premium parts to completely restore it. That includes a new rectifier, and high end coupling caps for the outputs. If you wanted to replace the can capacitors, instead of re-stuff them, that would add about $100. A quad of new production 7591s will run you about $100 for a matched quad. You're not likely to find a better amp for the cost it would take to restore that Fisher.

 

[yungin's-dad]

If you can use a soldering iron and read a schematic, then there is no reason to not rebuild it. Even if you have trouble reading a schematic, you'll find plenty of help here. As I said in one of your other replies, this is a great place to learn and get help. I for one owe this forum more than I've contributed, even though I try.

Good luck with your project. Those old Fishers are hard to beat, great amp.

Ron

 

[dsndblm]

I have an X-101-B that I restored about 1 1/2 years ago. It is a really nice sounding amp. I replaced all the power supply multi section electrolytics, all mylar caps were replaced, 7591 coupling caps were changed to .1 uf and grid resistors were changed from 300K to 220K. If you do a search on the grid resistor mod you will find a ton of info on the subject. Basically the mod allows the use of new production 7591 tubes.
I also found a couple of resistors in the power supply that had gone out of spec and replaced them.

The only drawback I've found with my amp is the bias circuit. The 101-B was designed to run the output tubes really hard. I've seen Fisher adds with claims of almost 60 watts output for the amp. In stock form running off a variac at 120 VAC my 7591's were drawing over 50ma each. I run my 101-B off a variac set a 115 VAC. With this voltage the tubes are drawing a bit under 40ma. That's still quite a lot of current but Fisher used the cathode bias current to power the filaments of four 12AX7 tubes in the amp. Dropping the cathode current really starts changing the sound because of under powered 12AX7 tubes.

I'll be happy to share any info I might have with you. There are a lot of guys on this forum that are willing to help as well.

Rebuild the amp and run it off a variac. They are truely amazing amps.

 

[CWelsh]

Thank you all for such quick and helpful responses. I don't know if I'm brave enough to tackle the rebuild myself, but it would certainly be a fun and interesting project. And, thank you all for the welcome to AK and offers of guidance if I decide to move forward with this. You can be sure I will take you up on your offers if I do.