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Fisher X-100B Recommendations and Advice

Discussion in 'Fisher' started by NaiveMelody, Nov 21, 2018.

  1. NaiveMelody

    NaiveMelody New Member

    Messages:
    13
    Hello, I am new to the forum and to the exciting world of tubes. I've wanted to buy a Fisher amp for a while now and I finally pulled the trigger on a X-100B on ebay last night. It is coming straight from a console and the photos looks great. This being my first tube amp I am slightly terrified about plugging this thing in when it arrives even though the previous owner said he had it up and running this week.

    A couple questions:
    When I receive it is there anything that I should do prior to plugging it in? Unfortunately I am a big fan of instant gratification and would really like to check it out as soon as I get it out of the box... but I also don't want to ruin anything.

    Eventually I'd like to give it a full service/restoration but I don't have the funds to do so at the moment. Is there anything I can do to get it up and running safely until I have the chance to get it to a professional? Please keep in mind that I've never worked on something like this before.

    Is there a ball park price range that I can expect to pay to have it serviced? If so, any idea how long something like this usually takes to complete?

    Is there any specific sort of cleaner that I should use (or avoid using) to clean up it up?

    When plugging in a component it looks like one of the plugs is inserted on the top and one is inserted on the back? Red top and black back? He is sending the original manual but i couldn't tell how this works from the photo.

    Thanks again in advance for any thoughts or suggestions. I really appreciate it!


    s-l1600 (3).jpg s-l1600 (2).jpg s-l1600 (1).jpg s-l1600.jpg
     
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  2. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,411
    Location:
    Melbourne, FL
    NaiveMelody,

    Welcome to AK and welcome to the Fisher forum.

    Nice score you have there. I have one of those in my queue to refurbish/repair and I have the kit version (KX-100) in my main system. They are fine amps. I'm listening to Jeff Beck right now through some KLH Six speakers. A sublime combination.

    And yes, all the connections for one channel are on the top of the chassis and the connections for the other channel are on the back of the chassis.

    Do you know what work was done on it before? Typically, you'll want to make sure the power supply is up to date with newer electrolytic caps and change out the couple of other electrolytic caps in there. I'd suggest an inrush limiter (CL-80 thermistor) be added to the AC side of the power supply (I actually added two). This will slow the ramp-up of voltages throughout during a cold turn-on and protect the power switch from the initial arc that tends to ruin them over time. Once I was sure that was done I'd bring it up slowly on a variac or a dim bulb tester and check the voltages throughout and give it a listen if I find everything in order at that point. From there you might determine that you need to clean all the switches and controls with Deoxit or you might find it needs work in some area or another.

    Oh, one thing I found was that I was able to go with a 2A fast blow fuse. I can't remember offhand, but it might be spec'd to use a 3A slow blow fuse. (I'd suggest you check what fuse you have right now too. I'm not suggesting you change it, but I'm giving you what I did.) I wanted the extra protection and interestingly I've never blown a fuse in it.

    They'll be some experts coming along soon to say hi and lend a hand. Just tell us what you find out and what you think you need.
     
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  3. NaiveMelody

    NaiveMelody New Member

    Messages:
    13
    Thanks for the warm welcome and for the info Tim! I'm not totally sure what work has been done on it so I will be getting a quote for a service from Casper at Stereorehab.com in Chicago once I receive it. He was recommended by a friend and was quick to respond to my email so I hope that it goes well. He "highly recommended" not even turning it on when I receive it which is a bit of a bummer but better safe than sorry I guess. Do you have any idea how much a service like this typically runs? I guess it goes with the territory but I was hoping to play with it a bit before investing more money into it. Thanks for the heads up about the KLH Six speakers, they look like they could be a great fit. I currently have some Wharfedale 10.1's but they don't seem like they are efficient enough for this amp. Thoughts? I will be sure to take some pics and give updates as this process unfolds. It would be great to be up and running by Christmas. Thanks again for all of the help and any additional thoughts or suggestions would be greatly appreciated.
     
  4. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,411
    Location:
    Melbourne, FL
    NaiveMelody,

    In terms of the Wharfedales, give them a try when you get it running. I can't comment on the Wharfedales specifically though. This amp turns out about 18 watts RMS/channel and while it isn't going to fill a stadium you might be surprised at what 18 Watts can do. I usually run mine at about 25% volume and it fills the house with nice thumping rock and roll but I can still talk. The amp has a nice solid low end thump to it that will surprise you (with the right speakers of course).

    I'm a newer hobbyist so take what I say with a grain of salt. There are experts here that can correct me where I'm wrong..... I am basically sharing what I have learned here and by doing it myself.

    He was right in asking you to not turn it on without knowing if the capacitors are replaced. The 50+ year old caps they came with could fail (if they haven't been replaced) and take other expensive parts along with it. Just better to be safe until it is checked out.

    Have you thought of doing it yourself? It will definitely save you money and it might add to the fun factor. There are a lot of AK'ers that started where you are at right now and they are off doing some serious advanced mods now.

    Not sure what it might cost as I have always done my own work. The topside caps can be expensive if you want to replace with nearly exact custom made multi-caps. There are sources that supply those and they look nice. Alternatives are to abandon the current caps in place (for appearances sake) and put the new caps underneath or to gut the cans on top and re-stuff them with skinny caps you can find from major parts suppliers. What your tech will suggest is probably to put them underneath to save money, but I'm just guessing. His labor will probably add up pretty fast. He might do the caps and check the tubes and voltages and maybe Deoxit the switches and controls then give it a listen to see if there are any problems. If he has a good tube tester he could check the output tubes and give you some measurements of the conductances of each (and he should label each with the values). This will tell you if they are close to being a matched set of four. If there are problems then the bill becomes more indeterminate. Not sure what else he might do. Note that I'm not trying to pile on to what he should do. This is only what I would want to have done if I wasn't going to do it myself. (I would do all this if doing it myself excepting that I don't have a tube tester that can do conductance. I had to measure the tubes in the amp itself to get the same info.)

    The minimum mod I would suggest is to ask him to add the CL-80 thermistor (one or two of them). It protects the fragile on/off switch on the volume control from getting burned, makes the voltage ramp-up gentle and lowers the overall voltage into the unit by 1 or 2 volts for each one you add.

    A second important mod (but if you are running out of money some might think this is optional) would be to add 100 ohm screen grid stability resistors for the output tubes. This prevents destructive arc'ing in the output tubes and is a highly recommended mod by many. I did this one.

    Further there are optional mods to:
    - Add 10 ohm cathode current measurement resistors. These can be used to find out the idle current of each output tube to make sure that they are all pulling their weight equally - so to speak. I did this one.
    - Allow individual output tube bias'ing. While that may not mean much to you - it is a lot like setting up the idle on a multiple carburetor engine. You want to have idle screws for each one. I did this one and my flavor is called an IBAM. There is another flavor called an IBBA.
    - Fix the headphone jack identity issue. I believe the channels are crossed in these units. Apparently this was built before there were standards as to which connection was left vs. right. I did this one.
    - Update the coupling caps. This one might not be needed as most of these came with nice foil caps that don't have an age problem like electrolytic caps. I changed mine out before I figured this out. In my next one (an X100B) I will check them out before replacing.
    - A change to the output tube bias and small signal tube heater circuit. Fisher did a combo circuit to combine the output tube bias with the small tube heater circuit to save money. There is a mod to separate out those circuits and it is actually a very cool but somewhat involved/complex mod. This will lower the idle current in the output tubes to extend their life, give the tubes more freedom to operate (means significantly more power output) and significantly lower measured distortion. I didn't do this in my KX-100 because it was my first project, but I've got some of the parts to do this in my X100B. [EDIT: This is combined with a mod called Enhanced Fixed Bias (EFB trademarked?) from Dave Gillespie. I haven't done this one.]
    - There are a few other mods out there to change the preamp section a bit and get rid of some of the parts in the preamp section that are less than ideal. There is a unity gain mod that elevates a phase shift in the amp that is less than idea. I haven't done any of those either.
    - EDIT: I think there is also a mod to remove a low pass filter in the preamp. I haven't done that one. My KX-100 has plenty of low end for now. Maybe I'll do this in my X100B that's in the queue.

    Note that I've been saying "idle current". That isn't really what it is called, but it is a good way to use a carburetor analogy to describe what is happening.

    Send us some pics when you can and ask lots of questions. This stuff is fun!!!!
     
    Last edited: Nov 23, 2018
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  5. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,411
    Location:
    Melbourne, FL
    Maybe some others might chime in to correct me or add to the conversation.
     
  6. 1rebmem

    1rebmem AK Subscriber Subscriber

    Messages:
    94
    Location:
    Wilmington, NC
    I don't have much for experience in this arena but I am currently restoring a Fisher 500B and I ended up cleaning the chassis and face plate with WD40.
    It really did a nice job! Didn't affect any lettering at all and removed all dirt/grime/buildup.
    If you decide to try that, I recommend trying in a small inconspicuous place, just incase.

    Jef
     
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  7. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,893
    Location:
    Glen Burnie Md.
    I use Scrubbing Bubbles (Bathroom cleaner) and a 1" or 2" chip brush. Then flush it with CRC QD Contact Cleaner. If a receiver, I'll hit that too with the QD. Never had one lose lettering with it yet. The less residue you have on it the better, the WD-40 leaves a residue. Put some Carnauba wax on the chassis afterward to seal it. .
     
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  8. gtxtom

    gtxtom AK Subscriber Subscriber

    Messages:
    188
    Location:
    Philadelphia, PA
    My first (and only up to this point) restore was on an X-101-B. I made a thread and got great tips and upgrade suggestions from Larry and Dave Gillespie. I bought new can caps from Hayseed Hamfest and the rest from mouser.com - again with help from Larry about type, etc. It turned out great. I did have some experience with soldering beforehand, but about no experience with desoldering. Everything went well in the end though.

    I'm sure there are plenty of differences between you 100 and my 101, but my thread might give you some insight from someone with limited electrical resto history.

    http://audiokarma.org/forums/index.php?threads/new-x-101-b-owner.810331/
     
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  9. NaiveMelody

    NaiveMelody New Member

    Messages:
    13
    Thanks for all of the responses, I really appreciate the help! I'm excited to share that my amp arrived by fedex this weekend. Unfortunately the seller didn't remove the tubes first so one of them was bouncing around in the box and another was tipped over a bit. I'm not sure how resilient they are (similar to a light bulb?) and I have no way of testing them. I'm hoping that I won't need to replace them when it gets serviced. It's taking a lot of self-control to not plug this in and check it out. I've read in other threads that I might want to hook it up to an external switch instead of using the knob? Thoughts? I did try the knob and it feels pretty solid.

    I'm meeting with Casper at Stereo Rehab this weekend so hopefully we'll have a game plan soon. From what I have seen so far it appears to be in great shape and I'm really excited about it. There is a set of EV4 speakers on CL by me that I might pick up if the quote I get from Casper isn't too high. Please see attached for some more photos (don't worry it's not hooked up yet). Thanks again for all of the help!
     

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  10. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,254
    Location:
    NYNY
    By trying the knob do you mean you turned the power/volume knob and heard and felt a discernible "click?" If so, chances are your switch is good and whether you continue to use it to power on/off will depend on what your tech does to suppress the arching that has killed many a Fisher switch. As has been suggested by TIm, a CL-80 thermistor would be appropriate for your unit. Still, having taken all the necessary switch preserving measures imaginable, I power on using a bucking transformer switch or a regular power strip.
     
  11. rufleruf

    rufleruf Poor Impulse Control Subscriber

    Messages:
    1,158
    I once bought a KX200 and it showed up with a couple of tubes that came loose bounced around a bit. They all survived and worked fine after the experience. the bent over one will likely just need pins straightened.
     
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  12. NaiveMelody

    NaiveMelody New Member

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    Thanks for the info Matt, here's hoping that is the case.
     
  13. NaiveMelody

    NaiveMelody New Member

    Messages:
    13
    Hi NotDigital, when I turned it the knob it made a solid click so hopefully that is a good sign. I'll recommend the method TimD suggested to the tech when I drop it off. I'll take a look at the power strip method a bit closer but I'd love to be able to feel that click every time I turn it on. Thanks again!
     
  14. NaiveMelody

    NaiveMelody New Member

    Messages:
    13
    Do I need to worry about dust etc accumulating on the chassis if I don't plan on using the wood cabinet? I'm assuming that it won't hurt anything if it's exposed as long as I dust it regularly. I've seen people use handkerchiefs for turntables, does anyone do this with amplifiers? It seems like the handkerchief might be a fire hazard. Any thoughts or suggestions would be appreciated. Thanks again everyone!
     
  15. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

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    3,285
    Location:
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    Power strip is the way to go on saving that hard to find almost irreplaceable power switch, my 2 cents. :)
     
  16. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,254
    Location:
    NYNY
    I wouldn't spend too much time worrying about dust. If you attend to it regularly, it'll be OK. Every once and a while, when vacuuming, I get out a 3" soft bristle brush and give it good swipearound sucking it all up with the vacuum nozzle. Done! Sometimes months pass and never had enuf accumulated to warrant a visit by the local fire dept. That's why I say don't worry.
     

     

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  17. bhamham

    bhamham AK Subscriber Subscriber

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    2,030
    Location:
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    That is a beautiful X-100-B, congratulations! I have two KX-100s - one I restored and the other is on the bench about to be. As Tim mentioned these are the kit form of the X-100-B. Both are very nice sounding units and I think you will really enjoy yours. Should compliment your vinyl playing very nicely!
     
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  18. fred soop

    fred soop Super Member

    Messages:
    2,028
    I'm presently reading "Grounding and Bonding for the Radio Amateur". One surprising thing (among many) they mention is that the typical inexpensive power outlet strip switch is NOT rated for repetitive load breaking and using it for such could be a fire hazard. They also mention that the MOV surge protection in these strips degrade with every clamped transient, lowering their resistance, leading to another potential fire hazard. The recommendation is a dedicated box with proper switch and surge protection.
     
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  19. NaiveMelody

    NaiveMelody New Member

    Messages:
    13
    Thanks for the suggestions, I'm glad that I can leave it exposed without worrying about anything (other than my kids grubby fingers). Thanks again!
     
  20. NaiveMelody

    NaiveMelody New Member

    Messages:
    13

    Do you think a floor switch (similar to a christmas tree cord with a button) or something similar would have the same issue? I'd like to do a dedicated switch but I'm not having a ton of luck on amazon. Another option was doing a wall socket switch with a remote control. Thoughts?
     

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