Fisher 400 Phono Stage Upgrade - Can I Do It?

tlarwa

Vinyl Lover
This from Sony6060 in a different thread:

"Nothing is fundamentally wrong with the Fisher phono stage. IMO I believe these reports are hearsay. In fact, what is the difference in-between any 12AX7 phono stage? They are all the same with exceptions of the quality of parts and the RIAA tuning.

I can make a Fisher phono stage sound lousy or great with choice of the phono tubes and coupling capacitors. And, a dozen audiophiles with very high-end systems cannot not be wrong. One audiophile is a recording engineer with select master recordings and serious playback equipment.

Two tubes will perform. Brimar CV4004. These are with box plate on one end and a wing on the other end plus are very expensive. Close second place is Westinghouse USA manufactured 12AX7 with short narrow plate and only $30 per tube with diligent shopping. I rolled about every tube, even 1952 Sylvania 12AX7 tall black ladder plate that produced a slight smearing or say just not enough airy response.

Next, change out the phono stage coupling caps to K40Y-9. If a slightly softer presentation is needed, replace one set of K40Y-9 with Sprague Vit Q. Less than stellar LPs will sound a little better.

The last few percent in performance will come forth with a RIAA replacement using close matched metal film and K40Y-9. If organ music is your delight, change the response curve for a lower response. Going too low in response may have rumble possibly showing up. I have not made measurements, but the stock Fisher RIAA is likely good to 25Hz @ -3dB. 3dB is not a lot of fall off. I should measure it soon."

My Fisher 400 has the BizzyBee mods, and is a terrific performer. I don't typically use the phono stage, opting instead for my Parks Audio Budgie. But with the addition of a new-to-me AR XA table, I'm now using the 400's phono stage. I'd like to make it as good as I can. Tube rolling isn't an issue, and I will try to score some Brimar's or Westinghouse 12AX7's as recommended. As for the coupling caps, is that something I can do myself? I can solder decently, and have recapped crossovers, but have never worked on a receiver. Let alone a tube receiver ... and I don't want to electrocute myself. I also don't want to mess this beauty up! So what do you think ... should I tackle it or leave it to someone else?

Tom
 
Keep posting I'm really interested in this subject.

In my case I use a Garrard 401 with two arms one sporting an Ortofon SPU with a SUT and the other a Mono GE VRII the Fisher 500c's phono stage certainly sounded better than the Linn Linto Phono stage I was previously using via the Aux so I sold the Linto.

If there is a way to get the phono stage performing even better I would be very interested so any advice /experience is greatly appreciated.
 
The Fisher phono section will perform to world class standards with a few upgrades. Change the existing .01uF ceramic coupling capacitor out to .01uF Vitamin Q and change out the existing .022uF capacitor to a Russian K40Y-9 .022uF capacitor. The capacitors are located at the bottom of the 12AX7 socket. I have seen both film type and ceramic type .022uF capacitors on stock Fisher products. The Vitamin Q capacitor is most common in a 200 volt rating and the physical size is best vs 400 or 600 volt rated capacitors. I use 400 volt rated K40Y-9.

Two top performing tubes perform excellent in the Fisher phono section. The best is Brimar CV4004 (12AX7) or any Brimar with a box appearance on one side and a fin on the other side of the plate. The Brimar with a fin on each side is a different design and not desirable.

The second best tube and more affordable is USA manufactured Westinghouse 12AX7 with the narrow short plate.

All report the difference is substantial.

Another upgrade is replacing the RIAA ceramic package. It has three wires and located next to the phono tube sockets. The change is not as substantial as the capacitor & tube changes, but still an improvement. I will be offering kits.
 
Thanks Sony6060

I guess my real question is how HARD is it to get in there and replace those caps? Is it something that can be done by someone without experience working on these? I've never even had the bottom off it before. I don't want to mess something up. Any advice on doing this work properly?

Tom
 
I guess my real question is how HARD is it to get in there and replace those caps? Is it something that can be done by someone without experience working on these? I've never even had the bottom off it before. I don't want to mess something up. Any advice on doing this work properly?

Tom

The capacitor locations are an easy access. The .01uF ceramic disc capacitor is located on top of the tube socket. The other .022uF capacitor is located off to the side of the tube socket. I recommend to take a few pictures of the phono tube socket area before start of capacitor replacement. Change out the capacitors at one 12AX7 socket at a time. How are your soldering skills?
 
I have a 500C that will be getting restored in the next few months and I plan to look into this as well. It's funny, I come from the guitar amp world and there, Mullard and Telefunken are considered two of the best 12AX7's made both is sound and quality. When I heard that is what Fisher chose, it made me want one more. So I find it funny people report the Brimar and Westinghouse outperform the stock tubes.

Now don't get me wrong, I have played with tube swapping before and always let my ears be the judge, I'm just saying it's an odd thing.

Thanks for the tip on the cap replacement. Certainly a very easy mod.
 
I have a 500C that will be getting restored in the next few months and I plan to look into this as well. It's funny, I come from the guitar amp world and there, Mullard and Telefunken are considered two of the best 12AX7's made both is sound and quality. When I heard that is what Fisher chose, it made me want one more. So I find it funny people report the Brimar and Westinghouse outperform the stock tubes.

Now don't get me wrong, I have played with tube swapping before and always let my ears be the judge, I'm just saying it's an odd thing.

Thanks for the tip on the cap replacement. Certainly a very easy mod.

I have restored guitar amplifiers so I get your post. Guitar amps sound great with some overdrive distortion. The Westinghouse and Brimar are very neutral sounding tubes and would likely be boring and sterile sounding in a guitar amplifier preamp circuit.

I do not like the Brimar at other locations in Fisher amplifiers & receivers- just too boring a sound. At the phono section the Brimar & Westinghouse tubes produce a neutral, airy and clear sound. That sound is 'jazzed up' downstream with other preamp tubes.

The 3rd place Sylvania 12AX7 tall black plate receives an honorable mention in the phono stage. The Westinghouse is affordable. I and a few others do not enjoy any other tubes in the phono section and the list is extensive.
 
The capacitor locations are an easy access. The .01uF ceramic disc capacitor is located on top of the tube socket. The other .022uF capacitor is located off to the side of the tube socket. I recommend to take a few pictures of the phono tube socket area before start of capacitor replacement. Change out the capacitors at one 12AX7 socket at a time. How are your soldering skills?

Thanks, Sony6060. I wouldn't call myself a solder artisan, by any stretch of the imagination, but I have been successful doing the soldering I've attempted so far. Anything to be concerned about, or any tips to help me be successful? Also, where should I order the caps from? I don't do much of this, so sorry for the newbie questions.
 
Thanks for the replies so far, so basically I would need the following :

1 x Russian K40y-09 Capicator like this http://www.ebay.co.uk/itm/Russian-P...?pt=UK_Guitar_Accessories&hash=item461ce5718d

1 x 0.1 uF Spargue Vitamin Q like this http://www.ebay.co.uk/itm/Tone-Caps...al_Instruments_Guitars_CV&hash=item417e60efc9

And then its trying to find a Westinghouse 12AX7 valve

Do you have any photos of the original & modification, it would certainly help locate the parts to be changed.

Thanks so much
 
Thanks for the replies so far, so basically I would need the following :

1 x Russian K40y-09 Capicator like this http://www.ebay.co.uk/itm/Russian-P...?pt=UK_Guitar_Accessories&hash=item461ce5718d

1 x 0.1 uF Spargue Vitamin Q like this http://www.ebay.co.uk/itm/Tone-Caps...al_Instruments_Guitars_CV&hash=item417e60efc9

And then its trying to find a Westinghouse 12AX7 valve

Do you have any photos of the original & modification, it would certainly help locate the parts to be changed.

Thanks so much

Stereo uses two tubes. These are the tubes with the shields and small bare wire connected from the chassis to the two sockets.

Parts-
2x Vit Q .01uF
2x K40Y-9 .02uF
2x Westinghouse 12AX7 tubes.

I will take a photo tonight.
 
If you want a reference, you can check out my post #138 in this thread:

http://www.audiokarma.org/forums/showthread.php?t=511867

where in I measured and posted the RIAA accuracy of the basic Fisher Phono preamp circuit, as found in my own Fisher 400 receiver.

Dave

Thanks again Dave.

Note- Dave is most familiar with the Fisher phono stages and in fact every detail about the Fisher receivers including precise measurements. The Fisher post by Dave is the most informative text I ever read. The phono upgrade will make a large improvement, however other mods will uncover higher performance.
 
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Thanks for the tip o' the hat Sony -- but when it comes to the sound of the components that makes up the Fisher designs, you're in a league by yourself!

Dave
 
Thank you for your phono section tips, Sony. I just happen to be working on replacing components in my 400 phono section as we speak. It's good to know your recommendations for which tubes to use as well. Your knowledge is very much appreciated!

John
 
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Before I order them - are these the right caps?

(2) .01uF/100V - Sprague Vitamin Q- 186P - paper in oil. ($5.35/ea)
(2) .022uF/1000V K40Y-9 Vintage Russian - paper in oil ($7.19/pair)

There's a 630V version of the K40Y-9 as well ... Which one do I want? I found these on www.theartoftone.com. Any other sources you recommend?

Tom
 
Sorry I take so long to reply

(2) .01uF/100V - Sprague Vitamin Q- 186P - paper in oil. ($5.35/ea)
(2) .022uF/1000V K40Y-9 Vintage Russian - paper in oil ($7.19/pair)

There's a 630V version of the K40Y-9 as well ... Which one do I want? I found these on www.theartoftone.com. Any other sources you recommend?

Tom

The Vit Q must be 200 volt rated or higher. 400 volt Russian is better due to smaller physical size. I buy from ebay. I do buy large lots from Russia for best price. My customers cannot afford more than $2 -$3 average per K40Y-9. 14x go into a Fisher receiver and a pair or two more expensive Vit Q.
 
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I have a later model 400 ... S/N 60329W. Are these cap values correct for all model years? Sorry, it just want to make sure I order the right values, and I read elsewhere that the Russian cap was .047uF, not .022.


The Vit Q must be 200 volt rated or higher. 400 volt Russian is better due to smaller physical size. I buy from ebay. I do buy large lots from Russia for best price. My customers cannot afford more than $2 -$3 average per K40Y-9. 14x go into a Fisher receiver and a pair or two more expensive Vit Q.
 
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