|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
97.84.205.208
In Reply to: RE: Scott 340B Receivers- Overlooked Bargains posted by sony6060 on August 15, 2014 at 10:13:47
The 340a is an excellent receiver and does not take a back seat to the 500c..The 500c has a cool tuner with the stereo beacon that locks in with a nice click and is a quiet tuner however,the 340B is no slouch as a tuner and the amplifier in the 340b is more dynamic, and much more supple than the 500c as well as being more linear.Most of this is due the driver circuit in the amp which is the 6U8 pentode/triode as opposed to the fisher which uses a 12AX7 to drive the 7591s..I am in the process of implementing the 6U8 driver in one of the 500c receivers I have.
The 12AX7 can drive a PP set of 7591s in pentode but they should have chosen the 6U8/6GH8 as driver because that is probably biggest difference between the 500c and 340b.
The reason you don't hear much about the Scott 340b in the audiophile community is because it lives in the shadow of it's older brother,the 340a which also has two GZ34s and the 350b tuner section and dial.
Honest amplification is better than excessive 2nd order distortion anytime.
Edits: 08/16/14Follow Ups:
Eli D.
The Fisher TA-800 uses a pentode/triode PI. I will be converting Fisher 400 to a 6BL8 PI.
Watch the heater current draw! The 6U8, etc., draw 450 mA. while the OEM 'X7 draws 300 mA. Don't "fry" the power trafo.
You may be better off appropriating the circuitry in (IIRC) Fisher's X-100. That setup uses the 'U7 section of a 12DW7/7247 as the phase splitter. The 'X7 triode is a fine voltage amplifier, but it SUCKS at other tasks. Using a 'U7 triode as the phase splitter disposes of the drive capability issue, without increasing the stress on the power trafo.
Eli D.
The 12DW7 is a good alternate. As Michael stated the 2x 6U8 family of tubes with 1.9 watts extra load on a 300+ VA (watt) transformer and 15 tubes plus two dial lights using 6.3 volts AC has no effect on the Fisher power transformer. The dial lamps could be replaced with LED type lights to recover the difference in current too.
I still prefer the Amperex 6BL8 with a socket converter as installed in an upgraded Fisher TA-800 for best sound. After extensive upgrades, that TA-800 outperformed the other Fisher 400, 500 & 800 receivers with same Vit Q & K40Y-9 coupling caps and same brands of tubes in power, preamp & phono sections.
So, my Fisher 400 will get the same TA-800 phase inverter design wired for 6BL8. I also like the Mullard E80CF.
Eli
The 500C has a huge power trafo as does the Scott 340B and Paul Gryzbek has converted many 500c and 400 Fisher amps to EL34s using the same power trafo. Even running the four EL34s which run almost 2.5 amps more total current,the power trafo stayed right at 6.37vac so there will be no issues running the 6U8.
Honest amplification is better than excessive 2nd order distortion anytime.
The 6BL8,the 6AN8,the 6GH8,or 6U8,any of those are fine for the PI/driver.
If you need a circuit,let me know.
Honest amplification is better than excessive 2nd order distortion anytime.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: