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Fisher X101B Questions

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Fisher X101B Questions

Postby Bengal777 » 07 Mar 2012 18:11

Hello All,
A bit about myself first since this is my first post. I'm an older guy that just got back into vinyl not too long ago, common story I bet. I've since aquired a Marantz 2230 and a Fisher X101B along with my JVC turntable.

I have a few questions about the Fisher. I just got it last night and it looks like it's new. I believe that the tubes haven't been changed. Got it from a professor who bought it new in 1963. So I got it home and up and running and it sounds good, no doubt. But a few questions.

What kind of speakers would be good with an amp like this? I have a pair of Cerwin Vega RE30's that I've had since college. I know they are not well regarded but I've liked them for a long time now and have been afraid of getting new speakers for fear they won't sound good. Any imput on Marantz Imperial 7s? Any other decent speaker? I'm not looking to take out a loan to buy a pair. Actually thought of trading the 2230 for a pair locally.

The other question I have is about running the amp. I am a guitar player but my only expierence with tubes is guitar amps. They are pretty much the same I'm assuming. There is a left and right Low Level pot on the amp that I think soaks the power tubes. Does that sound right? Some what of a gain pot where the master volume acts the volume level. That sound right?

I love tinkering with this thing. Thinking about calling in sick today to play with it! Thanks for all your help and thanks for a wonderful site. (And please forgive my spelling, my fingers type faster than my brain moves)
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Re: Fisher X101B Questions

Postby Bengal777 » 07 Mar 2012 19:08

Hum... I've been reading some threads and I'm over my head...

I just want a system that I'm happy with and I'm getting there. Trial and error and all.

I'm not into this to have the best system or one to beat people over the head with. I just want something that I like the sound from. Could care less if it's a $15,000 pair of speakers or a pair from Montgomery Wards, good sound is good sound.

I'm getting there but I'm not going to refinance my house to have a system that looks good on paper. And you can do that if you like, just not for me.

Thanks for all the posts here. It makes for great reading.
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Re: Fisher X101B Questions

Postby Alec124c41 » 08 Mar 2012 04:06

If it makes you smile when you listen, it's good. If it makes you reach for your guitar to join in, even better! :)

Cheers,
Alec
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Re: Fisher X101B Questions

Postby LPfan » 08 Mar 2012 08:38

The left and right low level pots adjust the gain from the pre amplifier that is handling the low level inputs. The low level inputs are MM phono and tape head.

It is also a good practice to replace the capacitors on such an old amp. Leaky and failing capacitors can damage output transformers and tubes.

Regards,

LPfan
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Re: Fisher X101B Questions

Postby aardvarkash10 » 08 Mar 2012 09:31

like most not-top-end tube amps, it is happiest with speakers that have a ruler-flat impedance curve and relatively high efficiency.

Complex cross overs are also a handicap, so a two-way design might be ok, a 3-way will invariably be marginal, anything more and you are asking the amp to push defecation to a higher elevation assisted by a sharpened length of foliage...

Not a lot of speaker designs in the last 25 years match this spec - they have been designed to match to huge output (MOSFET or other current driving) amps. The Fisher is most definitely NOT one of these.

The Marantz 7 is three way and rated at 96db(!... but wait...) at 0.5m! Yes folks a real spec sheet cheat quoting the half metre rating instead of 1m. Even then, it look extremely optimistic. I'd pick they would be lucky to come in at 89db @ 1m, probably closer to 86db...

Depending on your music preference, full range drivers could well suit you. Check them out if you lean more to choral or simple acoustic. They generally loose the edge when pushed toward orchestral and more complex musical forms (including multi-instrument rock)
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Re: Fisher X101B Questions

Postby Bengal777 » 08 Mar 2012 16:38

Alec,
Thanks for the kind words. I do play along with vinyl. Makes it more immediate that you only get 1 pass to get it right! It's a challenge.

LPfan,
Is there any way to tell if they are leaking? Sounds like a dumb question I suppose. I don't see any evidence of leakage but then again, I'm just looking for stains on the chassis.

aardvarkash10,
Thanks for the response. So let me see if I have your info correct. With this amp, it would be better to have 2 way speakers than 3 way? I have found a set of Monitor 5's here locally that I am going to check out this weekend. Any info there? I listen to all kinds of music except country. Right now I have Cheap Tricks "Dream Police" playing. Going to Amy Winehouse "Lioness" next then maybe a little Slayer "Hell Awaits" to get me off to work. My taste runs the all temps save country. Brad Paisly is a great guitarist but just can't get by the twang.

Thanks for the thoughts guys. I had thought I'd encounter some audiophile snobbery here and have not so far. I know what I use is not up to mosts specs but like Alec said, it sounds pretty freakin' good to me. But I can't help but think a new set of speakers would be quite tasty.
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Re: Fisher X101B Questions

Postby Bengal777 » 08 Mar 2012 16:51

Another question or 2.

I've read this amp is 52 watts. Now my father bought a Fisher tube amp kit in the 50s and he still uses it today so that amp and guitar amps are the only tube expierence I have.

Now with guitar amps, the more you soak or saturate the tube, the better the sound gets. Is that the same in this kind of amp? I like that it's not a moster because of volume issues. Even in a house I can't really pull off a valve guitar amp, just can't push it enough to benifit from the tubes so I play a SS amp at home. I assume that this amp and a guitar amp are really no different. So I really was looking for a smaller wattage tube amp and the fact that it reminds me of dear 'ole dads amp, well that's just a bonus.
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Re: Fisher X101B Questions

Postby aardvarkash10 » 08 Mar 2012 22:31

52 W? Maybe, with a tail wind... I haven't done the math but it looks to be biased into AB1 (diagrams for the X100C are on the hifiengine sister site), so with 7591 output tubes a figure in the mid 30's to early 40's is possible...

Guitars are looking for distortion, so yeah, wind that tube up to 11! Not so in hifi... So guitar amps are biased to run the tube in the "hot" end of its range and get heavy (controlled) distortion.

Hifi amps are designed to the other end. Distortion is NOT a desired outcome. So they are biased to give power without breaking over into a distortion mode. They WILL (like any amp) go there in the last n-th of the volunme control, and depending on whether its the front end or the power tubes that falls over first, you will get either subtle or real ugly distortion.

I don't know the monitor 5 (or any other production speakers) really. The trick for you is to get a good look at the imdedance curves for the speaker. Most modern speakers have a huge dip in the low end - nominal 8 ohm speakers can commonly go as low as 2 ohms - and a peak in the upper range that may be as high as mid 20 ohms (some even higher...). Thats an ugly range for a voltage output device like a tube amp to match to and will be especially noticeable with the type of music you are playing.

The efficiency of the speaker is less important given the listening conditions you list - and 35 odd watts of tube output is an easy match to 60 or more watts of SS just because of the way they break down at high output levels. So my earlier comment on efficiency is less important.

Ultimately if you are like me and scrounging at the cheap end of the market, you can, if you have time, buy 2nd hand, try, and sell on if they don't suit...

And no - I don't do snobbery - perhaps reverse snobbery sometines!

Just as an aside - if the amp is still running its original electrolytic caps and other such erderly parts, give some thought to replacing them. They have a nasty way of exploding and spreading goop through your amp...

Cheers
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Re: Fisher X101B Questions

Postby Bengal777 » 09 Mar 2012 04:12

That makes sense now that I think about it. Guitars want distortion, stereo amps do not.

Thanks for the info on checking for speakers. I'll check those impedence curves.

I think I got 52 watts somewhere online. It doesn't seem that loud at all. The only think I have is the 30 watt Marantz and it seems to me that the Marantz is a tad bit louder.
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Re: Fisher X101B Questions

Postby digitalisevil » 14 Mar 2012 14:40

I just restored a fisher 500B. It has pretty much the same preamp and amp section as your 101.

IMPORTANT: STOP USING THIS AMP UNTIL YOU RESTORE IT!!!

It was not that hard to rebuild the power supply, change the filter capacitors and adjust the grid bias(soaking?) to get the 500B running like new.

try getting ahold of Jim McShane and send him an email. he will quote you a parts list and instructions on some very important changes to make to adapt this VERY NICE amp into something you can enjoy for decades.

I am worried about your safety (this amp could start a fire if the grid bias goes bad and overheats the output transformers).

Here is a list of mods

1. get wiring schematic
2. get and install kit of replacement parts including the can capacitors
3. add 10ohm resistors on path to ground on pin 5 of power tubes
4. change bias resistors according to mcshane
5. plug the power cord into a surge supressor or something with a switch and NEVER use the power switch on the unit again - there is arcing there that will over time destroy your switch. so just plug it in somewhere else with a switch and use that switch to turn it on/off.


You have found a real treasure and it will be worth the $180 in parts to make it last.

Speakers: I am running some vintage DLK/2 3 ways from a thrift store that are crystal and holographic with this amp.

I suggest you try to find 70's to 80's vintage speakers for low money, I highly recommend finding some old DLK 1.5, 2's or 3s. I rebuilt the crossovers with new capacitors in my DLKs and it made all difference in the world.

I wish you all the best of luck with your new Fisher. I use mine with vinyl almost exclusively and I have never heard music so 3 dimensional in any system.
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Re: Fisher X101B Questions

Postby Bengal777 » 29 Mar 2012 18:49

digitalisevil,
Some good advice there. Any idea of how to get ahold of Jim McShane?

I will admit, I have done nothing to the amp and use it every day. I had it on yesterday while I took a day off to clean 300 albums from a recent craigslist find for about 7 hours. Works just fine. No fires or smells or burning insulation or conduit.

So how important really is that? I'm not poo-pooing your suggestions I'm just curious. I see alot of people that put the time into these old amps to make them sound great. This one sounds great as it is. Beats the hell out of my Marantz, and I love Marantz.

I don't have it on when not at home so no worries about a fire when I'm not there. I know some keep them on all day and night, not for me.

And about the powering on suggestion. I've never heard of anyone doing that before. How much less strain is it on the amp to just flip on a switch on a surgeprotector then to turn on the volume knob?

Just asking to gain some knowledge.
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Re: Fisher X101B Questions

Postby Bengal777 » 29 Mar 2012 20:58

Another question about this or tube amps in general.

Would there be a big sonic benifit to adding a Soundcraftsman PE2217?
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Re: Fisher X101B Questions

Postby josephazannieri » 29 Mar 2012 21:57

Yo Bengal777:

You inquired as to a speaker suitable for your Fisher amp. I looked at schematic on HFE, and it shows 7591 output tubes. This means that it is in the 25-30 watt per channel category. Might be more, but I am basing this guess on my memory of specs in RCA Receiving Tube Manual. The point is that this amp is not going to want to drive power hungry speakers like AR3's. This also suggests that your Cerwin-Vegas, which generally have a reputation for efficiency, would be a good choice for this amp.

Others have said that you necessarily want a ruler flat impedance curve, but I am not as demanding in that regard, because the output transformer will protect the output tubes. Tube amps are less able to produce the huge amounts of current demanded by inefficient speakers. My experience with tube amps is that they are less likely to be upset by impedance variations than transistor amps. I think you can use any decent sounding efficient speaker, and the more efficient, like the Cerwins, the better. I would look for a speaker rated at least 90 dB 1 watt 1 meter, and higher if you can get it.

A lot of guys invest in retubing these things and recapping them, which is a good idea if you are planning to use them in severe service. If you are not having trouble, amp may be OK, though. Turn out lights and watch the tubes, particularly the 7591 output tubes. If plates glow red at all, you need to stop using this amp and get it worked on. You will see the red glow on outside of plate and it will be readily visible if there. If the tube has any visible reddish coloration at all, you have a problem. Even a slight reddish quality is too much. I am not talking about filament glow, which comes from deep inside the tube and is yellow. Also you should put tubes in a tube checker and be sure that they are not gassy or grid-emitting or otherwies debilitated. A tube checker will spot these issues.

I believe that this unit has a signal processor loop. You can put the Soundcraftsmen 2217 unit in this loop and use it as an additional tone control. However, you should be able to remove the processor completely from the circuit so that it is only in operation if you are directly using it. (If you want, you can just use a DPDT switch to switch around the Soundcraftsmen.) You can also put the Soundcraftsmen on tape loop. That will allow it to be used only when tape monitor is in. I have a Dyna PAS-3X with a little box that provides old EQ curves. I put it on the "tape 2" input of my Hafler preamp, and I only switch it in when I am playing 78's. Adding in extra circuit elements will tend to add additional noise and distortion.

Other speakers? EV 12TRX-B's? Altecs? I remember the local HIFI store when I was in college, where they had tube amps similar to this one, and drove a set of Altec A-7's with them. 8) COOL! LOUD! And well within the capabilities of this amp. 8)

And good luck from the old efficient old tube checker,

Joe Z.
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Re: Fisher X101B Questions

Postby Bengal777 » 30 Mar 2012 17:14

Joe,
Thanks for the response! That was a lot of useful information.

About the speakers, since I've had this amp I've been talking to a guy with a pair of Paridigms. I went to his house to buy a Kenwood tuner and checked them out. Nice sounding speakers for sure, nice a small compaired to my Vegas but I'll be damned if these CV speakers don't sound pretty good. The bass response is very tight and punchy, the mids are not overly pushed and the highs are not searing. I am hesitant to replace these speakers now because when I've done that in the past and not been happy, life is not good. If it ain't broke, don't fix it I guess. I know nothing about these speakers so it's good to hear your opinion that these would be decent for this amp.

About the tubes. When you say to look for the plate glowing red, I read the base where the tube attaches? The metal around the connector? I will check that out. The only thing I've noticed with the tubes, well the Power Tubes I can't see the preamp tubes, is they look 'normal' in relation to the glow. But I will check that plate heating issue when it gets dark.

I found a Soundcraftsman locally but have not gotten it. I probably will not, again if it ain't broke. This amp sounds fantastic as it is so I'm hesitant to add anything to it fearing messing up the 'flow' of the sound.
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Re: Fisher X101B Questions

Postby josephazannieri » 30 Mar 2012 20:51

Yo Bengal777:

The plate of the tube is the metal outer casing that is inside the tube. It covers the grids and screens and other internal aspects of the tube. It looks like a metal tube with a metal cap on the top. It will normally be dark metal, gray or almost black. If you are getting a spotty red glow on the outer metal surface, you have a tube that is running away, and you should stop using the unit, Your problem may just be a misplaced bias setting, or it might be something organic where components need to be replaced. The tubes most prone to this problem are the 7591's, which are those 4 tall 9-pin jobs, 2 pairs, one for each channel.

I am not a big fan of the Cerwins, I was always more of an Altec and Electro-Voice man, but they make a lot of sound for not much watts, and lots of people like them. I have a pair of Altec A-7 component sets in big bass reflex enclosures with which I can achieve 94 dB in the tenth row of a thousand seat hall, and they only need 5 watts a channel to do it. Your Cerwins are in that category.

And good luck from that loud, glowing old guy,

Joe Z.
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