Jon Kasper
New Member
Hi All,
Hoping you might be able to take a minute and help me out with planning the path/next steps for upgrading my Fisher 400 receiver, later version. I''m a complete rookie when it comes to this and am out of my depth, so any time out of your day and any help/insight you're able to provide will be very greatly appreciated.
So the history is that I purchased this Fisher 400 receiver 6 months back via ebay... obviously lots of risk involved with doing that. Once it arrived I had a local tech take a quick look, fix a few minor items per some recommendations on this wonderful board, bring it up to speed on a variac and fix any minor issues to get it working.
I've been told the current status is as follows:
- a basic recap has been done for all necessary areas to make it operational
- the selenium bridge rectifier has been replaced with a new bridge rectifier.
- output tube bias has been changed from 5.6Kohm resistor to a 3.3Kohm.
- added set of four 10 ohm resistors between the output tube cathodes and ground in the power tube circuitry to act as fuses in the event of one of the 7868 power tubes shorting internally.
- thermistor has been installed to protect power switch
- the tech took a look at the tubes, and the output tubes need to be replaced quite badly, thought he other tubes are in ok condition though the tuner tube is near end of its life.
I did a quick inventory of the tubes installed in the unit, all appear to be original old stock as follows:
V1 - Sylvania
V2 – general Electric
V3 – Silvertone
V4,V5, V6 – FISHER
V7 – tuning indicator, couldn’t see
V8- Toshiba (toyko shibaura electric)
V9 - Toshiba (toyko shibaura electric)
V10- Sylvania
V11 – nothing on tube other than “ASB USA”
V12- ”made in usa fox PILOT radio”
V13- ”made in usa fox PILOT radio”
V14,15,16,17 original FISHER
V100 – BOGEN
V101-- ”made in usa fox PILOT radio”
V102 - Valvo
So it seems like a complete sorgasboard of tubes... maybe to get the unit running so the seller could move the unit on ebay? I assume this isn't ideal, but I paid for the unit at a bit of a discounted price based on the "as is" status... so to be expected I guess.
I've uploaded a bunch of pics below to show the details of the unit. Assuming the tech's work/assessment of the above work items completed to date is correct, I'd greatly appreciate your help in identifying the next areas of improvement and the next things to do to get it sounding its best.
I use this receiver as both a phono circuit as well as amp for my Rega planar 3 - TT into the Fisher, and the Fisher out to a pair of Klipsch Cornwall II. So looking to focus on the phono and amp circuits of the unit. Tuner isn't critical.
I definitely need to upgrade the output tubes (some leaks), the plan is to obtain a nice quad of the Eh 7868 new production which I am currently working on. Also have a pair of VITAMIN Q 0.1 uf 200V caps earmarked for the phono section.
On top of that, if anyone can provide:
- a quick look at the caps installed by both the tech as well as the ebay seller - would there be a decent improvement moving up to different caps throughout?
- does the above tube selection seem ok? Any glaring tubes to look at replacing?
- any other improvements you can spot that would make a significant gain to audio fidelity.
Looking to bring this to the top level it can be - plan is for it to be the workhorse in our home for the foreseeable future, and want to maximize its potential! It just sounds so musical, already so even though still work to be done... it's my baby and just want to make it as great as possible!
Also, I'm a finance guy, professional accountant, so if anyone has any non-audio financial questions/work totally willing to swap financial expertise for your audio expertise!
Cheers,
Jon
Hoping you might be able to take a minute and help me out with planning the path/next steps for upgrading my Fisher 400 receiver, later version. I''m a complete rookie when it comes to this and am out of my depth, so any time out of your day and any help/insight you're able to provide will be very greatly appreciated.
So the history is that I purchased this Fisher 400 receiver 6 months back via ebay... obviously lots of risk involved with doing that. Once it arrived I had a local tech take a quick look, fix a few minor items per some recommendations on this wonderful board, bring it up to speed on a variac and fix any minor issues to get it working.
I've been told the current status is as follows:
- a basic recap has been done for all necessary areas to make it operational
- the selenium bridge rectifier has been replaced with a new bridge rectifier.
- output tube bias has been changed from 5.6Kohm resistor to a 3.3Kohm.
- added set of four 10 ohm resistors between the output tube cathodes and ground in the power tube circuitry to act as fuses in the event of one of the 7868 power tubes shorting internally.
- thermistor has been installed to protect power switch
- the tech took a look at the tubes, and the output tubes need to be replaced quite badly, thought he other tubes are in ok condition though the tuner tube is near end of its life.
I did a quick inventory of the tubes installed in the unit, all appear to be original old stock as follows:
V1 - Sylvania
V2 – general Electric
V3 – Silvertone
V4,V5, V6 – FISHER
V7 – tuning indicator, couldn’t see
V8- Toshiba (toyko shibaura electric)
V9 - Toshiba (toyko shibaura electric)
V10- Sylvania
V11 – nothing on tube other than “ASB USA”
V12- ”made in usa fox PILOT radio”
V13- ”made in usa fox PILOT radio”
V14,15,16,17 original FISHER
V100 – BOGEN
V101-- ”made in usa fox PILOT radio”
V102 - Valvo
So it seems like a complete sorgasboard of tubes... maybe to get the unit running so the seller could move the unit on ebay? I assume this isn't ideal, but I paid for the unit at a bit of a discounted price based on the "as is" status... so to be expected I guess.
I've uploaded a bunch of pics below to show the details of the unit. Assuming the tech's work/assessment of the above work items completed to date is correct, I'd greatly appreciate your help in identifying the next areas of improvement and the next things to do to get it sounding its best.
I use this receiver as both a phono circuit as well as amp for my Rega planar 3 - TT into the Fisher, and the Fisher out to a pair of Klipsch Cornwall II. So looking to focus on the phono and amp circuits of the unit. Tuner isn't critical.
I definitely need to upgrade the output tubes (some leaks), the plan is to obtain a nice quad of the Eh 7868 new production which I am currently working on. Also have a pair of VITAMIN Q 0.1 uf 200V caps earmarked for the phono section.
On top of that, if anyone can provide:
- a quick look at the caps installed by both the tech as well as the ebay seller - would there be a decent improvement moving up to different caps throughout?
- does the above tube selection seem ok? Any glaring tubes to look at replacing?
- any other improvements you can spot that would make a significant gain to audio fidelity.
Looking to bring this to the top level it can be - plan is for it to be the workhorse in our home for the foreseeable future, and want to maximize its potential! It just sounds so musical, already so even though still work to be done... it's my baby and just want to make it as great as possible!
Also, I'm a finance guy, professional accountant, so if anyone has any non-audio financial questions/work totally willing to swap financial expertise for your audio expertise!
Cheers,
Jon