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Op Amp upgrade

#64
carvinbassplyr said:
If you are saying this because u know a way to easily indentify which is which...I'd love to be informed.
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I believe his point is that a TL072 relabeled as a TLE2072 will be nearly impossible to distinguish unless you have some rather expensive test equipment around to test the specs.

This is the most probable outcome from a counterfeit part: some cheap part re-labeled as an expensive one.
 
#65
Handyman said:
I believe his point is that a TL072 relabeled as a TLE2072 will be nearly impossible to distinguish unless you have some rather expensive test equipment around to test the specs.

This is the most probable outcome from a counterfeit part: some cheap part re-labeled as an expensive one.
Click to expand...

Well honestly I think that even relabeled tl072's would be a welcome improvement to all the tl082's that are currently installed throughout the entire preamp of my amp...
 
#66
I have an old SWR studio 220 that was always difficult to dial in a good sound. I am no expert, but IMO the simpler a design, the better it is going to sound. I believe the reason that Avalons sound so good is because the tone circuit is relatively simple. Just a hunch...
I built a preamp of an Alembic fx-1 (fender preamp) And it sounds amazing, only because it is so simple.
If I where you, I would loose the SWR or run a whole separate preamp (alembic clone) along with it
 
#67
Handyman said:
I believe his point is that a TL072 relabeled as a TLE2072 will be nearly impossible to distinguish unless you have some rather expensive test equipment around to test the specs.

This is the most probable outcome from a counterfeit part: some cheap part re-labeled as an expensive one.
Click to expand...

Not necessarily "expensive" when it comes to discussing test equipment, but not exactly "cheap" either.
 
#68
Precisionb87 said:
I have an old SWR studio 220 that was always difficult to dial in a good sound. I am no expert, but IMO the simpler a design, the better it is going to sound. I believe the reason that Avalons sound so good is because the tone circuit is relatively simple. Just a hunch...
I built a preamp of an Alembic fx-1 (fender preamp) And it sounds amazing, only because it is so simple.
If I where you, I would loose the SWR or run a whole separate preamp (alembic clone) along with it
Click to expand...
While the approach might be simpler (no EQ section and hardly any knobs to turn) I highly doubt that a $3k Avalon AD2022 comes by good tone by being "simple". A direct box is simple, and I sure wouldn't pay $3k for an over-sized direct box...
 
#69
carvinbassplyr said:
While the approach might be simpler (no EQ section and hardly any knobs to turn) I highly doubt that a $3k Avalon AD2022 comes by good tone by being "simple". A direct box is simple, and I sure wouldn't pay $3k for an over-sized direct box...
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Who ever said circuit complexity and price are directly proportional? The price tags on Alembic preamps are ridiculous, and they are stupid simple. Now I don't know exactly whats under the hood of an Avalon pre, but I imagine price tag is derived from its origin of manufacture, craftsmanship, engineering, quality of components, and a little bit of the name. Of course there is a little bit more going on then whats in a DI, but lets not make assumptions...
 
#71
carvinbassplyr said:
Well honestly I think that even relabeled tl072's would be a welcome improvement to all the tl082's that are currently installed throughout the entire preamp of my amp...
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I seem to recall looking at a GK one time years ago and being surprised to find TL082 in that unit... And I believe older Peavey also, although I don't count that for much...... they used a lot of things I didn't like..... Y5V or Z5U ceramic caps in the tone stack, etc.
 
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#72
FWIW, I'm also somewhat skeptical regarding buying ICs from China. Digi-Key ships very quickly.

The audible difference between TL082 and TL072 is probably negligible. They are from the same family, and maybe even made using the same process. TLE2072 is a newer part, maybe a little clearer sounding than the older TL parts, though I found it perhaps a bit edgy, IIRC. For FET input replacement, I think OPA827 sounds more open and musical, though it is not inexpensive. ADA4627-1 has also been highly recommended, though I haven't tried it yet.
 
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#73
12bass said:
FWIW, I'm also somewhat skeptical regarding buying ICs from China. Digi-Key ships very quickly.

The audible difference between TL082 and TL072 is probably negligible. They are from the same family, and maybe even made using the same process. TLE2072 is a newer part, maybe a little clearer sounding than the older TL parts, though I found it perhaps a bit edgy, IIRC. For FET input replacement, I think OPA827 sounds more open and musical, though it is not inexpensive. ADA4627-1 has also been highly recommended, though I haven't tried it yet.
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I've heard the difference btwn 72's and 82's is very audible...the 82's are usually described as "phatter" or "grittier" which makes sense considering there distortion characteristics. The 72's are described as fairly clear sounding and the 2072's even clearer and quieter.
 
#74
I dropped out of this one when it became obvious that the OP had already made up his mind about what he was going to do. The question that remains: Is he actually going to hear a difference in the end result because of the parts he changed or because he has convinced himself that there WILL be a difference.

My feeling is, as I posted earlier, that there will be no significant difference.
 
#75
BassmanPaul said:
I dropped out of this one when it became obvious that the OP had already made up his mind about what he was going to do. The question that remains: Is he actually going to hear a difference in the end result because of the parts he changed or because he has convinced himself that there WILL be a difference.

My feeling is, as I posted earlier, that there will be no significant difference.
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I'm expecting the change in tone to come from the AE bypass mod...all I expect from the tle2072's is for the preamp section to operate more quietly/cleanly since it is currently outfitted with tl082's which are "worse" than factory spec for noise and THD. Do I think it will sound like an Avalon AD2022, no. Do I think it will sound better overall, yes.
 
#77
UncleFluffy said:
DIYable, probably. But by the time you've built/bought your test gear or taken it to a tech you'll have spent 10x as much as you've saved by buying the parts on eBay.
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Someday I will write a brief article on the subject, but for now, I would suggest that with some effort and ingenuity, you can make considerable headway with free / cheap tools. I have done noise performance measurements using just the audio input of my PC, a free program called Visual Analyzer, and some odds & ends.

My secret is comparing the noise of the circuit with the input grounded, to the noise with the input hooked up to a 100k resistor, whose noise voltage can be computed.

BTW, the new OPA140 from TI looks interesting.
 
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#78
I'm with Paul. But if you hear a difference, you could before and after measure it, or record it, so the next person who investigates can get a grasp on if it's worth the effort.

I bet if you tried a more modern pedal preamp into the amp in, effect return you'd get some pretty good results.
 
#79
seamonkey said:
I'm with Paul. But if you hear a difference, you could before and after measure it, or record it, so the next person who investigates can get a grasp on if it's worth the effort.

I bet if you tried a more modern pedal preamp into the amp in, effect return you'd get some pretty good results.
Click to expand...

I used to use a preamp into a power amp setup...
Problem 1.) To much rack space...4 rack spaces taken up just by preamp and amp and I like to have a power conditioner.
Problem 2.) The eqing ability on the SM-900 is the best setup for me. I like the 2 channel 3 band semi parametric eq...no one else does that not even the eden navigator as one channel has less capability than the other.
I like the seperate preamp/power amp setup since you can get more power with less money but it was just to many pieces to hual around and not enough eq flexibility. I used a bass vamp into a QSC which wasn't the best, but that had the most eq flexibility in a preamp I could find.

While I loved the Avalon AD2022 for sessions once again I run into the not enough eq ability problem for varying live venues...the modded SWR just seems like a good compromise...
 

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