Hi all,
I got something cool for you today:
I created GIFs of how different Op Amps in my WHAMMY behave on transients, at different pot volumes.
Zooming on the (boring) 10kHz square wave, I noticed some major differences in the way each Op Amp transitions, which should be insignificant since the time constants involved are way above audible range, but I found some correlations between my subjective evaluations and the measurements below:
Blue - Signal generator (amp input)
Green - Op Amp Output
Yellow - Mosfet output (amp output)
AD8599.gif
Burson V6 classic.gif
Burson V6 vivid.gif
LM833N.gif
LME49720.gif
OPA1642.gif
OPA2107.gif
OPA2156.gif
Interesting to note how the LME49720 is a "try hard"
Subjectively, I prefer V6 vivid, then OPA2107 and OPA1642.
This V6 vivid seems to have 2 slew rates, the fast (25V/us) works at low levels, and the slow (4.5V/us) works at higher levels. Fun! no?
LME49720 has a gritty / itchy treble to my ears, and on the opposite, V6 classic lacks details and micro dynamics which makes it too boring.
OPA2156 seems to break loose when level increases too much (see glitch).
For other measurements like THD/IMD/noise etc, see my website in signature.
I got something cool for you today:
I created GIFs of how different Op Amps in my WHAMMY behave on transients, at different pot volumes.
Zooming on the (boring) 10kHz square wave, I noticed some major differences in the way each Op Amp transitions, which should be insignificant since the time constants involved are way above audible range, but I found some correlations between my subjective evaluations and the measurements below:
Blue - Signal generator (amp input)
Green - Op Amp Output
Yellow - Mosfet output (amp output)
AD8599.gif
Burson V6 classic.gif
Burson V6 vivid.gif
LM833N.gif
LME49720.gif
OPA1642.gif
OPA2107.gif
OPA2156.gif
Interesting to note how the LME49720 is a "try hard"
Subjectively, I prefer V6 vivid, then OPA2107 and OPA1642.
This V6 vivid seems to have 2 slew rates, the fast (25V/us) works at low levels, and the slow (4.5V/us) works at higher levels. Fun! no?
LME49720 has a gritty / itchy treble to my ears, and on the opposite, V6 classic lacks details and micro dynamics which makes it too boring.
OPA2156 seems to break loose when level increases too much (see glitch).
For other measurements like THD/IMD/noise etc, see my website in signature.
Attachments
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Very interesting Martigane, thanks for your time and effort. The subjective results graphic on your site is nice, looks like the 1642 is the best all rounder while the 49720 is the most laid back. For the money OPA1642 is a good one for sure.
If you are keen I would send you a few more to try if you have the lock down blues
:
OPA627HA, LT1128, LT1115, OPA1622, LT1028, LT1360. (all the mono's are in pairs)
Interested to see how the metal 627HA's compare. I was impressed with the 1622, sounded very nice, good for the money.
If you are keen I would send you a few more to try if you have the lock down blues
:OPA627HA, LT1128, LT1115, OPA1622, LT1028, LT1360. (all the mono's are in pairs)
Interested to see how the metal 627HA's compare. I was impressed with the 1622, sounded very nice, good for the money.
Yes, LME49720 sounds laid back , and OPA1642 is great for the price!
My favorite was OPA2107 (deep and dynamic bass, very nice extended highs without harshness), until I received V6 vivid which sounded the most balanced and dynamic, but sounded a bit harsh.. until I upgrade to a better DAC where it is now outstanding!
It' s as other poeple say, it will reveal a lot from source/recordings, so one might prefer a more relaxed experience.
If you can send some good Op Amps (not 20 ), I'd be willing to test (Subjective + Scope) more and share the results, assuming my other DIY project does not take all my time.
It' s actually a nice timing as I wanted to make a second round of Op Amp evaluation, since I now have the V6 classic as well.
I' ll PM you my address.
My favorite was OPA2107 (deep and dynamic bass, very nice extended highs without harshness), until I received V6 vivid which sounded the most balanced and dynamic, but sounded a bit harsh.. until I upgrade to a better DAC where it is now outstanding!
It' s as other poeple say, it will reveal a lot from source/recordings, so one might prefer a more relaxed experience.
If you can send some good Op Amps (not 20
), I'd be willing to test (Subjective + Scope) more and share the results, assuming my other DIY project does not take all my time.It' s actually a nice timing as I wanted to make a second round of Op Amp evaluation, since I now have the V6 classic as well.
I' ll PM you my address.
Pretty interesting Martigane.
I am very curious to see your measurements of passive420's chips.
I listened to all of them (except opa1622). From passive's opamps I preferred opa627HA. But then I prefer v6 classic for my own listening.
I haven't heard vivid.
Your blog looks very interesting!
I am very curious to see your measurements of passive420's chips.
I listened to all of them (except opa1622). From passive's opamps I preferred opa627HA. But then I prefer v6 classic for my own listening.
I haven't heard vivid.
Your blog looks very interesting!
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Shielded Transformers for Whammy
I've been hunting high and low for a shielded (steel can) transformer (toroid) for the Whammy project and wanted to ask the forum for recommendations for North American sources. I have tried Antek, but they only have a shielded (surrounding the toroid with mu metal) option not a on steel can type. Both Plitron's and Toroid's websites seem to be messed up right now (any search for products returns nothing or a circular reference). I've tried Mouser and Digikey but they seem to only have similar options. Those are the only places I've ordered xformers from in North America and have struck out so I was hoping someone here could recommend some options.
I've been hunting high and low for a shielded (steel can) transformer (toroid) for the Whammy project and wanted to ask the forum for recommendations for North American sources. I have tried Antek, but they only have a shielded (surrounding the toroid with mu metal) option not a on steel can type. Both Plitron's and Toroid's websites seem to be messed up right now (any search for products returns nothing or a circular reference). I've tried Mouser and Digikey but they seem to only have similar options. Those are the only places I've ordered xformers from in North America and have struck out so I was hoping someone here could recommend some options.
Isn't mu metal specifically chosen to maximally reduce magnetic flux? This is a good thing and makes it better than a steel case
That's why I asked what at the MU version would be wrong.Isn't mu metal specifically chosen to maximally reduce magnetic flux? This is a good thing and makes it better than a steel case
It is the best material to shield a transformer.
You can bend a shield made of MU Metal yourself, but the material must be annealed again after processing.
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Great design, fun build - but have a hum/buzz
Not sure where I'm getting it, but I've got a hum/buzz. This isn't my first build, I normally build tube amps, and know the importance of ground loops and star grounding. BTW love the design and was looking forward to this build for weeks.
I searched this thread for other "hums/buzz issues" and did see several, but all were around shielded cable (which I used - micro coax) and grounding (which I did a star ground scheme - green wires. Moving the twisted wire AC run to the front panel switch didn't make it better or worse. I also have ground runs to each metal panel as well as a ground point in the middle of the PCB. The RCA jacks are isolated from the back panel. The 1/4 phono jack isn't isolated, but grounded to the coax as well as to the star ground. I didn't use coax to the Pot, but did twist leads. I can't believe not mounting the Pot to the PCB directly could cause this much hum.
The hum increases with higher volume, it's there where I have the inputs connected or not. Bad enough that it's not really usable - very sad. I'm wide open to ANY ideas. Pictures attached.'
Thanks in advance,
Michael
Not sure where I'm getting it, but I've got a hum/buzz. This isn't my first build, I normally build tube amps, and know the importance of ground loops and star grounding. BTW love the design and was looking forward to this build for weeks.
I searched this thread for other "hums/buzz issues" and did see several, but all were around shielded cable (which I used - micro coax) and grounding (which I did a star ground scheme - green wires. Moving the twisted wire AC run to the front panel switch didn't make it better or worse. I also have ground runs to each metal panel as well as a ground point in the middle of the PCB. The RCA jacks are isolated from the back panel. The 1/4 phono jack isn't isolated, but grounded to the coax as well as to the star ground. I didn't use coax to the Pot, but did twist leads. I can't believe not mounting the Pot to the PCB directly could cause this much hum.
The hum increases with higher volume, it's there where I have the inputs connected or not. Bad enough that it's not really usable - very sad. I'm wide open to ANY ideas. Pictures attached.'
Thanks in advance,
Michael
Different regulated voltages on the + / - rail
My Whammy got ready tonight and works fine.
However, I have slightly different regulated voltages on the + / - rail, + = 16.63v and - = 16.91v.
I built the Configuration 2 - “LED reference” and used Motorola MC7815CV / MC7915CV as a voltage regulator.
I measured the regulator before installation and the 7815 has an output voltage of 14.91v and the 7915 has 15.19v, so it is clear that the difference of +/- comes from the voltage regulator.
What can I do to get the same +/- voltage? Without filtering voltage regulators.
My Whammy got ready tonight and works fine.
However, I have slightly different regulated voltages on the + / - rail, + = 16.63v and - = 16.91v.
I built the Configuration 2 - “LED reference” and used Motorola MC7815CV / MC7915CV as a voltage regulator.
I measured the regulator before installation and the 7815 has an output voltage of 14.91v and the 7915 has 15.19v, so it is clear that the difference of +/- comes from the voltage regulator.
What can I do to get the same +/- voltage? Without filtering voltage regulators.
Hi Roland,
I'm just a beginner in DIY electronics, but I'd try shunting the diode D6 with a resistor, effectively decreasing the voltage boost done on your MC7915 since that one is a bit too strong.
D6 drop = 16.91-15.19 = 1.72V , so roughly 20mA, which is behaving as a 85ohms resistor in this case, to my understanding.
So if you want to loose 0.3V from that 1.72V, you'd need the equivalent resistance to drop to 71ohms.
-> Try adding something close to 420 Ohms in parallel to D6.
Or maybe wait for some guru advice, I'm just playing in the sandbox here
I'm just a beginner in DIY electronics, but I'd try shunting the diode D6 with a resistor, effectively decreasing the voltage boost done on your MC7915 since that one is a bit too strong.
D6 drop = 16.91-15.19 = 1.72V , so roughly 20mA, which is behaving as a 85ohms resistor in this case, to my understanding.
So if you want to loose 0.3V from that 1.72V, you'd need the equivalent resistance to drop to 71ohms.
-> Try adding something close to 420 Ohms in parallel to D6.
Or maybe wait for some guru advice, I'm just playing in the sandbox here
Enjoying the results
Just got a build started..and semi finished. Figured I'd give a test run before going much further. Tack soldered a power cord to do the PSU test and left it in place. Added input and output wiring and jacks, plugged in an old pair of HD 25's just in case something bad happened, and plugged in the power. Hit play on the CD player, turned the volume up, and voila!...Hey, there's music. Switched over to the HD 650's and things got better. I had been using an Asgard 3...that will go up for sale. The WHAMMY/HD 650 combo is excellent, with more detail and better transients than with the Asgard. Can't be missing any detail now...and this combo absolutely loves percussion. First into the played was Little Feat / Waiting For Columbus..one of the best live rock albums with a drum set that has an excellent mic setup. Next up..Paul Simon / Graceland...then Vangelis / Alexander...James Gang / Rides Again...Paul Winter / Canyon. Everything sounds great...couldn't really ask for much more. Put player on pause and turned the volume way up...not a hint of noise...and that's with just tacked in wiring and not a finished ground scheme. I'll be using a Galaxy 2U case...230mm x 280mm, so there will be a little room to play with. I want to use 2 pairs of inputs and switchable inputs. Power switch on the back a la Asgard. So the extra room will work out and help keep power wiring in the back. But for now, I'm just enjoying the hell out of the SQ. It's not always easy trying to figure if some projects are worth the effort compared to something out of the box, especially when all evidence is anecdotal. I can definitely recommend this one...especially for anyone with HD 650's. I should have dropped the f/stop a bit in this pic but was in a hurry, so the depth of field could be better. I'll get another shot when it actually gets into the cabinet.
Just got a build started..and semi finished. Figured I'd give a test run before going much further. Tack soldered a power cord to do the PSU test and left it in place. Added input and output wiring and jacks, plugged in an old pair of HD 25's just in case something bad happened, and plugged in the power. Hit play on the CD player, turned the volume up, and voila!...Hey, there's music. Switched over to the HD 650's and things got better. I had been using an Asgard 3...that will go up for sale. The WHAMMY/HD 650 combo is excellent, with more detail and better transients than with the Asgard. Can't be missing any detail now...and this combo absolutely loves percussion. First into the played was Little Feat / Waiting For Columbus..one of the best live rock albums with a drum set that has an excellent mic setup. Next up..Paul Simon / Graceland...then Vangelis / Alexander...James Gang / Rides Again...Paul Winter / Canyon. Everything sounds great...couldn't really ask for much more. Put player on pause and turned the volume way up...not a hint of noise...and that's with just tacked in wiring and not a finished ground scheme. I'll be using a Galaxy 2U case...230mm x 280mm, so there will be a little room to play with. I want to use 2 pairs of inputs and switchable inputs. Power switch on the back a la Asgard. So the extra room will work out and help keep power wiring in the back. But for now, I'm just enjoying the hell out of the SQ. It's not always easy trying to figure if some projects are worth the effort compared to something out of the box, especially when all evidence is anecdotal. I can definitely recommend this one...especially for anyone with HD 650's. I should have dropped the f/stop a bit in this pic but was in a hurry, so the depth of field could be better. I'll get another shot when it actually gets into the cabinet.