The Fisher X-100-A

Yes,
For any integrated with five tubes up front instead of six, the absolute phase is off.

Ok, my HK A500 is 5 tubes front (two 12AX7's and one 12AU7) so it is plagued by the same bug...

However, like I said, I do not hear the difference.

When I surfed the web about it, I read about the fact that sometimes, the recordings are out of phase anyway. Sometimes, it's the entire recording, sometimes the drums...

To resume, even if the system is correctly phased, the recording could be 180 degrees out of phase.
 
I forgot: I also read that some speakers have phase inversion between internal drivers (woofer out of phase with the tweeter).

Just to add to the confusion.

Someone could try the blindtest and post the results? Curious here...
 
There's different ways to parse everything.
Phase for this isn't phase for that.
Inside speakers, on some three ways, the mid speaker is out of phase with the others, or should I say, polarity is intentionally miswired to the middle speaker. That's an entirely different thing than absolute phase in an amplifier.
Speaker driver phasing in passive networks:
The capacitors and inductors in a speaker crossover are designed to act as low-pass or high-pass filters with a controlled attenuation slope. The networks that do the filtering have a side effect of making the phase of the signal that passes through them either lead or lag the input signal. Some inductor/capacitors networks were called lead-lag networks. Well, if the high pass filter going to the mid is greater than 90 degrees out with the phase of the driver it's working with, it makes sense to increase the lead value to 180 degrees if you can appreciably change the lead without changing the frequency or the slope much and wire the crossover to the driver reverse the phase to that driver.

Speaker phasing in an amplifier:
That's not to be confused with absolute phase of an amp. Yes, there are inductors and caps in an amp so it can get confusing. What we're talking about is that when a kettle drum is hit, does the output to the speaker push forward or pull back? The strike should push forward. Well, I've been told that you need two tubes in each stage and that one inverts the phase of the signal and the second, aside from adding gain and other goodies, returns the absolute polarity to correct. You can test for this. I have but the evidence comes from the speakers, so caveat emptor.

I have a speaker pulse tester from Navone Engineering called the PD-11 but a google search will turn up many such tweaks and appliances. Mine was called a PD-10 but was changed to PD-11 with a sharpie at the factory. It comes as a package with a test box with a red and a green LED, a button, two leads, and a disk where you're instructed to play a certain track. The pulses show green if the speaker is pushing out towards you on the pulse. The pulses on the CD are repeated for a minute or two, and you can repeat the track, and the reader displays red if the speaker is pulling in on the pulses. It was designed for car audio, but I use it to make sure my speaker drivers are in phase with each other and that the pulse that's supposed to push the drivers out does, in fact, push the drivers out.
There are others out there that a quick google search will find for you that accomplish the same task.
 
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I just made the blindtest (first link in my readings post).

I got 6/10... So it looks I can't heat the difference with a guitar recording. In my case, as my Fisher is wired correctly, I should had recognized the inverted as the good one and original as the phase-inverted...

Sure, I could reverse the plugs on my Wharfedales for peace of mind.
 
Oh! Another one: it looks the tape loop of the X-100 has one less stage of amplification (compared to tuner, aux or phono) and thus, is 180 degrees out of phase in respect with the other inputs...

As I listen a lot to my computer soundcard going through the tape loop, I assume that when doing it, the absolute phasing is now correct?

I read about it on the Fisher Yahoo group: http://launch.groups.yahoo.com/group/fishergroup/message/2173

This reply particularly: http://launch.groups.yahoo.com/group/fishergroup/message/2175

Also, as the phono stage is another gain stage, does it mess things up (again)?
 
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Well, I reversed the plugs on the speakers and tested basically by putting my fingers on the woofer with loudness comp. on: bass hits looked synchronized with a push on my fingers (cone going outward). I would say it's ok...

Now, I don't hear any difference...:)
 
If you're happy, it's right.

For me, if the source puts out a pulse that goes positive and the speakers also put out a positive (forward) pulse, regardless of the contortions that happen within the signal chain, I'm happy.
 
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I have an X100 that has been in our family since the early 1960's. My dad bought it new. I had it re-capped, etc. a while back. Currently it's running with Klipsch Forte II's and that seems to be great combination. I also have it connected to a restored Fisher R200 tuner and am using a Sony Playstation (model SCPH-1001) as a CD player.
 
fisherx100a.wordpress.com you can see from here.
real x 100A or x 100 2

That circuit is the same as the one (incorrectly) labelled X-100-A at http://www.one-electron.com/FC_Consumer.html and mentioned by ciscokid and also at http://www.tubesrit.com/audio/thumbnails.php?album=38. It uses 7591s in the output (with 430V plate, 360V screen), whereas the real X-100-A (& X-100-2) use 7189s (the military EL84M should be OK too) with 390V plate, 340V screen. The input stage looks much the same, but the phase inverter voltages are different, and since the output stage 7189s have 18V on G1 vs 26V in that other circuit, the cathode bias resistors/heater values are different, as is the feedback resistor & cap, at a glance. I have right here a genuine Fisher X-100-A/X-100-2 (the "2" is in a subscript) service manual (well, most of it!) including the schematic, but my scanner is packed away. I'll try to remember to upload it (and write to one-electron.com!) when I can. I can confirm it does look the same as the one at Fisher Doctor, http://fisherdoctor.com/pictures/fisher/amps/x-100-2.jpg. Really 390V is too high for plain EL84/6BQ5 (300V design-centre) so they may not last too long if you try to use those. Hope that's useful meanwhile!

[Edit: I've been reminded that the cathode is at 30V, so 360V (less ~5-10V again across the OPT?) across the tube.]
 
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That circuit is the same as the one (incorrectly) labelled X-100-A at http://www.one-electron.com/FC_Consumer.html and mentioned by ciscokid and also at http://www.tubesrit.com/audio/thumbnails.php?album=38. It uses 7591s in the output (with 430V plate, 360V screen), whereas the real X-100-A (& X-100-2) use 7189s (the military EL84M should be OK too) with 390V plate, 340V screen. The input stage looks much the same, but the phase inverter voltages are different, and since the output stage 7189s have 18V on G1 vs 26V in that other circuit, the cathode bias resistors/heater values are different, as is the feedback resistor & cap, at a glance. I have right here a genuine Fisher X-100-A/X-100-2 (the "2" is in a subscript) service manual (well, most of it!) including the schematic, but my scanner is packed away. I'll try to remember to upload it (and write to one-electron.com!) when I can. I can confirm it does look the same as the one at Fisher Doctor, http://fisherdoctor.com/pictures/fisher/amps/x-100-2.jpg. Really 390V is too high for plain EL84/6BQ5 (300V design-centre) so they may not last too long if you try to use those. Hope that's useful meanwhile!

In my case, the originals 7189's are testing good but I have a spare set of Russian 6p14p-ev. X-100-2 here...
 
I've tried the following in my X-100-3 with GE triple mica black plate 5751s in the first two positions and Sylvania long pinched plate JAN 12AX7s in the tone control section and Fisher/Tele ribbed plate 12AX7s in the phase inverter positions. I like them best in the following order:
Sylvania yellow letter 7189
Fisher (probably Amperex) 7189
6p14p
New Mullard 7189

The Sylvies do everything right. They present stunning yet uncluttered microdetail. The Fisher/Ampies are good too, but different. Perhaps it's my system that has strayed a bit from what makes the Amperexies shine their best. Or I could have adjusted my system around the Sylvies a bit, because I have had them longer. The others are a touch bright for my taste.
They've all had more than 100 hours on them, with the new Mullards having 300 hours on them. I can live with all of them, even the Mullards.
 
I've finally gotten around to scanning all the pages I have (in order) from the Fisher X-100-A manual. They're large images scanned at 300dpi for printing, although filesizes have been kept to under 150KB (from 92KB to 141KB actually) and are all line-art gifs except the cover which is a reduced quality greyscale jpg. (the handwriting is from a previous owner!)
You can view or get the full-size image (right-click, save as etc. on Windows) from the landing page of each link below:

Fisher X-100-A_SM_cover
Fisher X-100-A_SM_parts list
Fisher X-100-A_SM_circuit_p1.
Fisher X-100-A_SM_circuit_p2.
Fisher X-100-A_SM_circuit_p3.
Fisher X-100-A_SM_mains transformer voltage taps
Fisher X-100-A_SM_AC balance adjust

I've also emailed these to John Atwood (one-electron.com) so perhaps he'll correct those there.
Hopefully these (or at least the circuit/schematic pages!) can replace the other wrong ones out there as well...
And maybe they'll be useful to others looking for Fisher X-100-A data in the future ... :thmbsp:

Enjoy!
 
I'm more than happy with my Scott 299A but I couldn't help the compulsive purchase of a Fisher X-100 (X-100-3? X-100-A?) for $120. It's the model with four 7189's, five 12AX7's, and all of the plastic control knobs are the same size.

It looks brand new, with all of the original paperwork, schematic, and a bunch of Fisher advertisements. The original owner said he bought this one, listened to it a couple times, then built his own amp. He said this amp sat in a closet for 40+ years.

My live-in girlfriend hates my stereo collecting and this amp immediately went into storage. :no: So I feel inclined to sell it, but I'm still very curious about how it would stand up against my Scott 299A. Any thoughts?

Also, this amp came with a quad of Fisher-labeled Mullard 7189's with supposedly very few hours on them. I plan on yanking them, as the original Amperex 7189's in my Scott are getting a bit worn out. Would Russian Reflektor 6n14n tubes work in the Fisher x-100 or would they get fried rather quickly?
 
I'm more than happy with my Scott 299A but I couldn't help the compulsive purchase of a Fisher X-100 (X-100-3? X-100-A?) for $120. It's the model with four 7189's, five 12AX7's, and all of the plastic control knobs are the same size.

It looks brand new, with all of the original paperwork, schematic, and a bunch of Fisher advertisements. The original owner said he bought this one, listened to it a couple times, then built his own amp. He said this amp sat in a closet for 40+ years.

Mine (which has been shamefully shelved for many years with a stalled PSU upgrade - must get it out & finish it!) came with Telefunken 7189s, but some years earlier I had bought a matched quad of Sovtek EL84M for it which are still unused.

My live-in girlfriend hates my stereo collecting and this amp immediately went into storage. :no: So I feel inclined to sell it, but I'm still very curious about how it would stand up against my Scott 299A. Any thoughts?

The only way you'll know is to listen to both ... 299A as it is, X-100-A as it is, then its 7189's in the 299A, perhaps. I don't know the Scott at all, what if any bias adjustments; the Fisher has none, and uses effectively a shared cathode resistor between all 4 output tubes... I guess a matched quad is the best you can do for it, without modifications. You might be better off getting new tubes for the Scott; I'd think the Fisher would have a far higher resale value with the original Fisher tubes, and that back-story!

Also, this amp came with a quad of Fisher-labeled Mullard 7189's with supposedly very few hours on them. I plan on yanking them, as the original Amperex 7189's in my Scott are getting a bit worn out. Would Russian Reflektor 6n14n tubes work in the Fisher x-100 or would they get fried rather quickly?

NB that the "n" seems to be a visual representation of the Cyrillic П, which is otherwise transliterated as P, so (from the first link below) Russian 6P14P (Cyrillic: 6П14П) tubes. You need the -E suffix versions, it seems, which are equiv. to EL84M/7189, not the plain ones which are = plain EL84 and won't last.

Searching "Sovtek EL84M price" just now on Google brings some interesting links in the first few, including some discussions on the Russian tube variants (you need the higher voltage military etc versions as above) from here and here (NB the EL34/84 typo) (both in a music amp context) Some links there to reviews too.

But there's a range of vendors and prices in other links on that Google search.

I don't know how my earlier Sovtek EL84M relate to current production (or even how they sound vs 7189) yet.
But thanks to this and other posts I've become aware of those other Russian tubes, which seem worth looking at.
 
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Scan those originals!! (nicely!;=}))

It looks brand new, with all of the original paperwork, schematic, and a bunch of Fisher advertisements.

A sudden thought and a plea ... <there is no angel prayer icon!!> ;=})

The service manual pages I posted above are all I have. They may be incomplete...
As already noted, there's a scarcity of literature on the net for these.

How about organising, if possible, to scan these;- even the advertisements might be appreciated by many, even now, if not later - so that there's a better & more available, even tending permanent, record? ;-?

Could work out best places to reposit them later ... just please consider how! ;=})
(there are sites loving old hifi adverts, and circuit diagrams, service manuals)

This is a great site just retrieved from my bookmarks which could be useful:
http://www.scantips.com/
(and which maybe I should have restudied! - you'll need to "fit to page" to print the above gifs.)

Best wishes to all,
 
My live-in girlfriend hates my stereo collecting and this amp immediately went into storage. :no: So I feel inclined to sell it, but I'm still very curious about how it would stand up against my Scott 299A. Any thoughts?

Man, you need another girlfriend. The way I look at it is your not out drinking, gambling or consorting with other women when you are enjoying your stereo collection. That should be enough.
 
Man, you need another girlfriend. The way I look at it is your not out drinking, gambling or consorting with other women when you are enjoying your stereo collection. That should be enough.

+1

One woman friend left me because she did not like motorcycles, well that, and the fact that I went out with a younger woman. :D

After two transitional girlfriends later, I met and married my wife, who like motorcycles, and good music! :banana:
 
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