high blend. can it be added to a tuner?

[packrat]

Can a simple high blend cricuit be added to a tuner? Sometimes the hiss on weak stations is a bit much. I was thinking that it could be added right onto the output RCAs jacks of the tuner, and then it would be fixed and permanent. Some tuners have two outputs, a fixed and variable, so this could provide one output with a hi-blend and the other wide open. You could even have both hooked up to the 'tuner' and 'aux' inputs of the preamp and just select whichever 'tuner' suits the station.

I vaguely remember an article in Audio (or even Stereophile?) about adding this circuit, but I don't remember the details. It was as simple as a small capacitor and resistor in parallel across the left and right signal wires, to combine the high frequencies to mono. Problem is, I don't remember the values used. Any ieas???

 

[Tom Bavis]

I'd try a 1K in series with each tuner output, and a .022 uF across the outputs to the amp. If you have some old interconnects to hack up, you can try different values - high level, so shouldn't introduce any hum.

 

[mhardy6647]

Tom:

I am not thinking this through, but wouldn't that just filter the HF? The idea of HF blending is to eliminate the out of phase noise between L and R but not to attenuate the HF (right)?

 

[Punker X]

Because I have a KT-8300 in front of me right now.. Looking at the scat, all the MPX filter does is High-blend with as Tom said, a .022uf cap across the outputs just before the muting relay no addition resistors. This particular had been previously modified by APS with their special blend circuit modification "to reduce noise in stereo without having to switch to full mono".. this special circuit is a 5.6K ohm resistor also put across the outputs in parallel with the cap. This reduces separation even further.

I've seen high-blend circuits that is just resistor across outputs. Some Sansui's have a noise amp that drives a optical coupler, as the noise increases the resistance decreases and the higher the blend you have.

X

 

[jblmar]

Yes and No. Any circuit can be made and added. The problem appears to be the tuner. Your tuner may need more signal to quiet. High Blend reduces the high frequency response while maintaining the stereo broadcast. Try a higher gain antenna.
Ron

 

[packrat]

thanks for the tips!

Yes, a better antenna does help, but sometimes there is still a little bit of hiss there. This is a 'problem' only because I listen with headphones. Makes me think that what I really should do is put the high-blend onto the headphone jack. I'm also thinking of adding this to a receiver I use at work, where I think I'd have to put the 0.022 cap across the L/R inputs of the selector switch.

Thanks!