Image is higher on different amp
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DaveVoorhis
Addicted Member
The location of a sound is determined by slight left-to-right differences in what the brain identifies as the same sound, which are due to phase and frequency response differences caused the folds/ridges in the ear. See https://en.wikipedia.org/wiki/Auricle_(anatomy)#Notch_of_pinna
Amplifiers and other parts of the audio system also cause similar slight left-to-right phase and frequency response differences that the brain interprets as information about the location of sound.
Different amplifiers have slightly different left-to-right phase and frequency response differences, which the brain interprets as the sound coming from slightly different places.
Note that volume difference can exaggerate the effect. If the two amplifiers are otherwise very similar in frequency response, phase differences, etc., it may simply be that their volume levels were slightly different.
DaveVoorhis
Addicted Member
Or... That.
The reason I noticed this is the tuner string broke on the cr-800. An unplanned A/B of the two. Raising and lowering of volume made no difference in image placement. The bias and idle on the cr-800 had just been set. 0.00 volt bias and 0.015 volt idle current. The allowable idle current is 0.005 to 0.023. I may adjust it higher and see what happens.
DaveVoorhis
Addicted Member
Adjusting bias, DC offset, etc., should only be done following the manufacturer's instructions in the service manual, or if manufacturer's instructions are unavailable -- or for verification -- with a sine wave input and an oscilloscope and set for minimal DC offset and bias for minimal crossover distortion.
I have and used the manual for the adjustments. Both sides were equal on dc offset= midpoint voltage and bias=idling current. The idle current is set slightly lower because the variable resister was stable at the lower setting. At the higher 0.023 setting it wants to creep up. I will try again to set it at 0.023 volt / 23 millivolt.
Restrung the tuner. This thread helped. http://audiokarma.org/forums/index.php?threads/where-to-buy-tuner-dial-cord-string.86036/ Used the 65lb test line. Image dropped into place after going to proper idle current setting. Surprises me that the setting made that big of difference. This hobby is full of wtf moments.
sKiZo
Hates received: 92644 43.20°N 85.50°W
Yah - different amps = different top end response, and that's what will affect the tweets (and overall imaging) the most.
Ditto for speakers, or even modding the same speakers. I replaced the tweets and upper mids on my McIntosh XR16's some time back and the height difference was immediately noticeable with no other changes.
PS - it can be electronic tweaks as well. I have a Carver H9AV that has a unique circuit (precog) that allows you to change the apparent height on the fly ...
Don't use that much, but I can say the effect works a LOT better since replacing the stock Malysian ICs in the circuit with TOTL "redline" TI equivalents and later version browndogs in critical positions.
Ditto for speakers, or even modding the same speakers. I replaced the tweets and upper mids on my McIntosh XR16's some time back and the height difference was immediately noticeable with no other changes.
PS - it can be electronic tweaks as well. I have a Carver H9AV that has a unique circuit (precog) that allows you to change the apparent height on the fly ...
Don't use that much, but I can say the effect works a LOT better since replacing the stock Malysian ICs in the circuit with TOTL "redline" TI equivalents and later version browndogs in critical positions.
doctor fuse
Super Member
The higher amp is smoking stronger stuff. *Spliffff!*
chadbang
Well-Known Member
I always knew when I had my superbly imaging Spica TC-50s set up properly when they imaged not only horizontally, but also threw a huge vertical soundstage. Example: If you're listening to a male vocalist placed center stage, you can raise your chin up and the image of his voice will continue to rise upward as you tilt your head back, e.g. an image that extends floor to ceiling in height. That always told me when I had my Spicas precisely dialed in. So my theory is that your receiver which throws the "higher" (IF the center image rises as you tilt your head back) presentation may be imaging better.
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restorer-john
Addicted Member
The dial string helped 'tie down' that floating image. 
cheapcuts
Member
Old thread but possibly helpful, My Yamaha cr-800 has about a total of 36 inches total of internal speaker positive.lead wire from rear of amp to speaker selector switch then back to speaker terminals. The negative speaker lead to the main caps is about 6 inches long in comparison. I did a quick cowboy fix of adding 30 inches of rolled-up wire to the negative speaker wire. Presto very nice imaging receiver. To hear the effect you will need capable speakers.The built-in fm tuner can deliver a stereo image with a good signal Very enjoyable sound for a 50 year old amp.
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Yah - different amps = different top end response, and that's what will affect the tweets (and overall imaging) the most.
Ditto for speakers, or even modding the same speakers. I replaced the tweets and upper mids on my McIntosh XR16's some time back and the height difference was immediately noticeable with no other changes.
PS - it can be electronic tweaks as well. I have a Carver H9AV that has a unique circuit (precog) that allows you to change the apparent height on the fly ...
Don't use that much, but I can say the effect works a LOT better since replacing the stock Malysian ICs in the circuit with TOTL "redline" TI equivalents and later version browndogs in critical positions.
Beware the precognition matrix. That sounds scary... I need to look up what the hell that H9AV is...
Yeah. I went and looked it up as well. I just get a kick out of how Bob labeled things. The precognition matrix.... LOL.
