The Stereophile - Bob Carver Challenge (Bob wins!):
http://www.diyaudio.com/forums/showthread.php?postid=152392#post152392
Eva's point can't be over emphazied, frequency response differences have to be considered The 1st order amp difference in listening tests
eq/shaping the amp's forward transfer function and modifying feedback and zobel to tweak the output Z at the amplifier terminals controls loudspeaker's final ouput, if you get these right you can make a solid state amp indigstinguishable from a tube amp in sound (barring clipping)
http://www.diyaudio.com/forums/showthread.php?postid=152392#post152392
Eva's point can't be over emphazied, frequency response differences have to be considered The 1st order amp difference in listening tests
eq/shaping the amp's forward transfer function and modifying feedback and zobel to tweak the output Z at the amplifier terminals controls loudspeaker's final ouput, if you get these right you can make a solid state amp indigstinguishable from a tube amp in sound (barring clipping)
jcx:
Very true, but as always, these truths go against the interests of most salesman, that are the ones that fund magazines with their paid ads. They do a prety good job fooling us into thinking that esoteric stuff has actually something of esoteric in it and that it's worth the money they ask us for. Don't disappoint them or they will do their best to shut you up.
Very true, but as always, these truths go against the interests of most salesman, that are the ones that fund magazines with their paid ads. They do a prety good job fooling us into thinking that esoteric stuff has actually something of esoteric in it and that it's worth the money they ask us for. Don't disappoint them or they will do their best to shut you up.
I don't want to argue with EVA or JCX 
. Modifying component/values in the same amp does gives different sonics.
I can hear difference between miller cap 33pf or 100pf, as long as you do it with A/B selector with the same amp (left and right) at instance (with a A/B switch). If you take too much time between A and B, you will forget
. Modifying component/values in the same amp does gives different sonics. I can hear difference between miller cap 33pf or 100pf, as long as you do it with A/B selector with the same amp (left and right) at instance (with a A/B switch). If you take too much time between A and B, you will forget
This is difficult. If the trebles are easily modified, making solid bass or midrange is difficult. There is only 1 way to do it, make the amplifier free of intermodulation. If you have done it right, even with 10 or 20W power amp, you will feel that the sound is already "right", powerfull. If you don't do it right, even with 250W power amp, you will feel something is missing, or the bass/midrange has no "weight"
Some things I noticed while 'tweaking" an amp recently..
The amp sounded pretty good to begin with,but the high-end seemed rolled off.
I fiddled with bypass caps,etc. untill it got pretty good.I found this to be tricky -you have to experiment to get the right combination.
I ended up with film+foil input coupling caps,and also as bypass caps in a couple places,and those dipped mylar? (green 'chicklets') in other places.Ohh,and some tantalum too! It took me 2 days of soldering to find this combination,and it *rocks* in this amp!
The next thing, -Muting transistors on the amp's input,I didn't even realise they were there! (they would have been the first things to go!) I yanked them out and it was *worlds* better.The top end was clear and crisp! I think this SS amp is on the level of some good Tube amps now.
Then I replaced the shielded wire carrying the signal from the RCA jacks to the amp-board. I was using some 'cheap' shielded wire like you'd find for the CD-rom audio cable in your PC. 2cond+shield.
I cheanged it to 2 seperate 1cond+shield wires,and the sound became "veiled"..It sounded better with the 2 cond wire (and it's little bit of cross-talk).
You just have to play around a bit and see what strikes your fancy.What sounds good to you,in your system,might be completely different than another guy,and his system.
That was one thing I 'tweaked' on this amp Originally there were 100pf ceramic caps,and I eventually settled on 47pf Tantalum's,I think. There wasn't a whole lot of difference in my case,but it did clear the top-end up a bit.
The amp sounded pretty good to begin with,but the high-end seemed rolled off.
I fiddled with bypass caps,etc. untill it got pretty good.I found this to be tricky -you have to experiment to get the right combination.
I ended up with film+foil input coupling caps,and also as bypass caps in a couple places,and those dipped mylar? (green 'chicklets') in other places.Ohh,and some tantalum too! It took me 2 days of soldering to find this combination,and it *rocks* in this amp!
The next thing, -Muting transistors on the amp's input,I didn't even realise they were there! (they would have been the first things to go!) I yanked them out and it was *worlds* better.The top end was clear and crisp! I think this SS amp is on the level of some good Tube amps now.
Then I replaced the shielded wire carrying the signal from the RCA jacks to the amp-board. I was using some 'cheap' shielded wire like you'd find for the CD-rom audio cable in your PC. 2cond+shield.
I cheanged it to 2 seperate 1cond+shield wires,and the sound became "veiled"..It sounded better with the 2 cond wire (and it's little bit of cross-talk).
You just have to play around a bit and see what strikes your fancy.What sounds good to you,in your system,might be completely different than another guy,and his system.
That was one thing I 'tweaked' on this amp Originally there were 100pf ceramic caps,and I eventually settled on 47pf Tantalum's,I think. There wasn't a whole lot of difference in my case,but it did clear the top-end up a bit.
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