I am not too sure weather this is the correct place to post this or not.
I mod my D/A but it doesn't sound as I expected. The original chip was OPA2134. I replace it with BD adaptor to place 2x 627 SMD on the DAC.
It sound like Low Pass filter activated somehow. What could be a problem?
I mod my D/A but it doesn't sound as I expected. The original chip was OPA2134. I replace it with BD adaptor to place 2x 627 SMD on the DAC.
It sound like Low Pass filter activated somehow. What could be a problem?
it couldn't hurt to have (free) RMAA tests before and after just to make sure something did't happen during the swap
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but detailed memory for sound is usually considered one of our poorer human abilities - usually only gross features get transfered to long term memory and a suprizing amount of our "memory" is is reconstructed on the fly with the new input only having to hit a few key points
for reliable aural comparision few seconds of switching time and careful level matching is necessary to begin to make valid distinctions of small differences - blind testing also helps increase reliability by reducing expectation effects
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but detailed memory for sound is usually considered one of our poorer human abilities - usually only gross features get transfered to long term memory and a suprizing amount of our "memory" is is reconstructed on the fly with the new input only having to hit a few key points
for reliable aural comparision few seconds of switching time and careful level matching is necessary to begin to make valid distinctions of small differences - blind testing also helps increase reliability by reducing expectation effects
I tested that by swapping out the 2134 to 627 and back. Could it be the lower than optimum supply voltage? What would be a minimal burn-in time for 627? it now has about 30 hours.
In some systems the 627 does indeed sound dull. Local PS bypassing with suitable caps like ERO 1837 may help some.
That's well known. The OPA2134 is designed for audio and it hears. The OPA627 is not designed for audio and it hears too. Even the OPA827 is not mainly designed for audio, and it still hears.
Go with the OPA132UA, if you want a real good FET opamp. It's a definite upgrade over the dual (and lower grade) OPA2134, trust me.
i.e. you need to color the sound through some peculiar sort of power supply bypassing... I know. I have used this trick with the (less dull than an OPA627) LME49710NA, and it works well.
I brought my 627 from a dealer in Bangkok "hifimod" What is the effect of having a bit low voltage anyway? I thought 627 will sounded more open than 2134 but instead sounded more dull.
If you don't perceive sonic color(s), then certainly you won't perceive the OPA627 as duller than the OPA(2)134. But for all those who do perceive it...
I believe that the OPA627 would have never become so popular in audio forums (interesting not in commercial audio, even highest-end) if more people were sensitized to the tonal side of sound. I continuously hear people speaking of bright and dark - it seems all that they are aware of..
Goes completely against my experience. The only way do do a reliable sonic comparison is to first become addicted to an opamp's sound - then when you change the opamp you'll hear the difference in an instant. Now become addicted to the new sound, then try to go back. You can't go wrong this way.
Quick A/B switching is useless because the brain gets addicted to a sound and takes a little time to refresh and appreciate a difference. That way you get to think that all opamps sound the same!
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Andrea, now you are talking about something you don't know anything about.
Most opamps are for industrial use which also are good for audio if the speed is high enough but if you read the datasheets for mentioned opamps:
OPA134:
APPLICATIONS
l PROFESSIONAL AUDIO AND MUSIC
l LINE DRIVERS
l LINE RECEIVERS
l MULTIMEDIA AUDIO
l ACTIVE FILTERS
l PREAMPLIFIERS
l INTEGRATORS
l CROSSOVER NETWORKS
OPA627:
APPLICATIONS
l PRECISION INSTRUMENTATION
l FAST DATA ACQUISITION
l DAC OUTPUT AMPLIFIER
l OPTOELECTRONICS
l SONAR, ULTRASOUND
l HIGH-IMPEDANCE SENSOR AMPS
l HIGH-PERFORMANCE AUDIO CIRCUITRY
l ACTIVE FILTERS
As you too will notice, audio is the primary specified application of the OPA134, and the last one(s) mentioned of the OPA627.
I don't think that the OPA627 sounds bad, but there's better these days. OPA1611, OPA211, OPA827, LT1028 come to my mind first.
However, the OPA2134 keeps being a musical opamp with a rich tonality. That's why it's so widely used. I recommended the OPA132UA because with it the rich tonality wouldn't be lost, and contemporarily there would be a reasonable gain in transparency.
Probably the most interesting FET opamp of all is the new ADA4627-1, though.
I don't think that the OPA627 sounds bad, but there's better these days. OPA1611, OPA211, OPA827, LT1028 come to my mind first.
However, the OPA2134 keeps being a musical opamp with a rich tonality. That's why it's so widely used. I recommended the OPA132UA because with it the rich tonality wouldn't be lost, and contemporarily there would be a reasonable gain in transparency.
Probably the most interesting FET opamp of all is the new ADA4627-1, though.
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Do you know why? OPA627 has more precision when it comes to DC paramterers and also lower noise.
Both mean nothing to me. The OPA134 has them both already very good. I would go with the OPA134 simply on the basis of sound quality. The OPA132UA is a little more refined.
The OPA827 is a better alternative to the OPA627, with slightly more dynamics and (sonic) precision than the OPA132UA, but not yet the tonal richness of the latter.
It might have to do with the price difference. Prices at Farnell:
OPA627
276,52 - 1 331,79 SEK (divide by 10 to get EUR)
OPA134
12,58 - 30,62 SEK
OPA2134
23,74 - 39,82 SEK
Low noise and high performance for DC costs to manufacture. Those two parameters are really important in signal conversion.
Or that the sound of the OPA627 doesn't justify its price. 🙂
Again I'm not saying it's a bad sounding opamp. It's inoffensive sounding, and that's a good thing. It's pretty detailed too. Tonally...it's lacking. Like the (also expensive) AD8610.
Anyway... if the OP can use bipolar opamps (I guess he can), I suggest trying 2x LT1028 (ACN8 or CS8) for the kind of upgrade that he looks for.
Again I'm not saying it's a bad sounding opamp. It's inoffensive sounding, and that's a good thing. It's pretty detailed too. Tonally...it's lacking. Like the (also expensive) AD8610.
Anyway... if the OP can use bipolar opamps (I guess he can), I suggest trying 2x LT1028 (ACN8 or CS8) for the kind of upgrade that he looks for.
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