[billinkansas]

Fisher questions for the Vintage & Tube Guys

I enjoy reading the posts from mkmelt, tuberoller, and some of you other tube cats on this forum, Vintage Asylum, and Audio Karma. I’d like to pick your brains - I have a Fisher 500c in original condition. It sounds pretty darned good with headphones, but strains a bit with speakers. I know it needs a thorough refurbishing, and am prepared to spend some good bucks to do it. My back-up is a Harman Kardon HK-450 that really sounds good with the Beyer DT-880 cans, soundstage is almost as wide as the Fisher, but a lot cleaner and deeper bottom. (HK-450 handily outperforms my Creek OBH-11, IMO)
My questions to you tube guys are:

Can I expect the Fisher's headphone performance to blow away the Harman Kardon after a rebuild?

During a refurbish job, are there any tweaks to improve the lowest bass response of the Fisher?

Thanks much!!

 

[mkmelt]

Your Fisher 500C is rated at 34 watts per channel RMS. This should be enough power for driving most speakers of at least average sensitivity (88db/1watt @ 1 meter) in an average sized room. If you like to listen at near concert levels you will definitely need more power or different speakers with a higher sensitivity. Klipsch Heresy speakers, for example, have a sensitivity of 96db/watt. A pair of these speakers, when driven by your Fisher 500C, could play louder than you would ever need. Then again, you might not like the sound of the Heresy speakers compared to your current speakers. The midrange is forward sounding and except for a mid-bass rise at just over 80Hz, the Heresy speaker has a steeply rolled off bass response below this frequency.

If you have not done so, have the tubes in your Fisher 500C checked. You may need to replace the driver/inverter tubes or the 7591 output tubes. Also, there are coupling capacitors throughout the amplifier that degrade over time and need to be replaced.

Most tube amplifiers use output transformers and coupling capacitors in the final output stage. Both of these are going to limit the audio bandwidth of the amplifier somewhat. The very best output transformers, the kind used in top line equipment such as your Fisher 500C, are designed to minimize roll off of the lowest bass. When compared to the low bass response of your HK 450 the low bass response of the Fisher is still going to be down several db in the range of 30Hz. On most music this is not noticable except by direct comparison to a direct coupled solid state amplifier such as the HK.

The Fisher 500C may sound better than the HK in the midrange, on vocals, and when reproducing brass and string instruments. With an high resolution digital or analog source the Fisher 500C will reproduce more of the ambient information from the recording.

 

[billinkansas]

Mkmelt,

Thanks for a very good response. I like the term "ambient information". This is what I like about the Fisher - the music seems to take place in a slightly larger and more acoustically favorable place than with my s.s. amps. The sound is wider and a little more "present", I only wish that it could be as deep.

I have some rather power-hungry Yamaha NS690 speakers that I bought used in 1977 when I was in college. I had a Marantz 2230 then that did ok, later a Yamaha NS640 and Luxman L430, each better than the last. The Yamahas sing in a whole new way with the Fisher - I like the sound enough to have the Fisher overhauled. Of course, the Fisher is fabulous with the Beyer DT 880s, even in its current condition.

BK