I used R9=1270 Ohm, C34=1nF
It gives a -3db corner frequency of 125000Hz as in George's original suggestion except with lower overall gain of the original.
I dont think it is because of NOS topology. Both the NOS version and my own version using 8x oversampling pmd100 have similar energy and drive.
BUF03
I was the guy way back when that made the original recommendation to use the BUF03 off the TZ. It is a good performer. The OPA627 (soic) is actually better and now the OPA1641 outperforms that. If your interested in holographic imaging.
I was the guy way back when that made the original recommendation to use the BUF03 off the TZ. It is a good performer. The OPA627 (soic) is actually better and now the OPA1641 outperforms that. If your interested in holographic imaging.
DS vs Multibit
Hi quatran, I recently did a comparison of my PCM1704 dac vs my replacement Sony UHP-H1. This is before moving on to a OPA1641 buffer. They had the identical output level and I did an A B for hours. The SONY (Delta Sigma dac) had a less focused sound stage. The instrumental outlines were fuzzy and indistinct. The 1704 dac was sharply focused, faster sounding and the treble was delicate and accurate. Completely agree in your assessment.
Hi quatran, I recently did a comparison of my PCM1704 dac vs my replacement Sony UHP-H1. This is before moving on to a OPA1641 buffer. They had the identical output level and I did an A B for hours. The SONY (Delta Sigma dac) had a less focused sound stage. The instrumental outlines were fuzzy and indistinct. The 1704 dac was sharply focused, faster sounding and the treble was delicate and accurate. Completely agree in your assessment.
I think they are special, but they get bad press/reviews from users that have not purchased wisely and got fakes, there are many fakes of these around, and they look identical.
So get them from reputable suppliers that are BB affiliate, and pay the right money for them.
Cheers George
Hearing is very subjective and depends on various factors. In my experience, if we put a small resistor before the RCA socket in some case it makes quite a big difference compared to a direct connection from the opamp output as this resistor minimizes the effect of interconnect cable on the sound.
Some opamp has stronger driving capability than others even though the sound quality may not be better or even worse. In such case it depends on the load and the cable.
Some opamp has stronger driving capability than others even though the sound quality may not be better or even worse. In such case it depends on the load and the cable.
Your right Quan but I would try never to use a resistor at the output even high
quality ones. As for BUF03 not only does it sound good when properly set up it's
other virtue is it's high current drive which makes cable issue almost redundant
accept for tuning SQ for personal liking
Cheers
quality ones. As for BUF03 not only does it sound good when properly set up it's
other virtue is it's high current drive which makes cable issue almost redundant
accept for tuning SQ for personal liking
Cheers
If you use a decent quality resistor it's almost impossible to hear any color added by it because the value is only about 100 ohm or less ie a fraction of the load. Any noise or distortion cause by this small resistor is very very small to be audible. The key point is that it is placed before the cable and the load is after the cable. Without this resistor the output stage will see cable capacitance directly.
BUF03's
Hi sumotan, BUF03's are quite good and a little bit ahead of it's time. I have used those at various times over the years. Holographic imaging depends largely on the speakers. Having adequate power and a clean preamplifier in my experience. I use LT1083's for regulation most of the time. Configured for positive and negative voltage. My preamp is true dual mono and I think that helps ultimate channel separation. A BA-3 Nelson Pass design with Didden Jung super regulators. The sound in my system using the BUF03's is rich with a large soundstage. Not the last word in detail. Likely due to higher distortion levels. The OPA627's in SOIC are more detailed and image slightly better. The distortion specs are much better as well. The OPA1641's have a lot more going on especially in regards to holographic imaging. They have a nice smooth sound that the OPA627's lack. This could be system specific. So if your real happy with the BUF03's in your system then enjoy them. I have no qualms about using them in projects where a Class A warmth is needed. I have large ribbon tweeters and a planar magnetic bass system. The Magnepan MG2.5R's have improved crossovers. About 300 Watts per channel on tap.
Hi sumotan, BUF03's are quite good and a little bit ahead of it's time. I have used those at various times over the years. Holographic imaging depends largely on the speakers. Having adequate power and a clean preamplifier in my experience. I use LT1083's for regulation most of the time. Configured for positive and negative voltage. My preamp is true dual mono and I think that helps ultimate channel separation. A BA-3 Nelson Pass design with Didden Jung super regulators. The sound in my system using the BUF03's is rich with a large soundstage. Not the last word in detail. Likely due to higher distortion levels. The OPA627's in SOIC are more detailed and image slightly better. The distortion specs are much better as well. The OPA1641's have a lot more going on especially in regards to holographic imaging. They have a nice smooth sound that the OPA627's lack. This could be system specific. So if your real happy with the BUF03's in your system then enjoy them. I have no qualms about using them in projects where a Class A warmth is needed. I have large ribbon tweeters and a planar magnetic bass system. The Magnepan MG2.5R's have improved crossovers. About 300 Watts per channel on tap.
Wondering if the perceived improvement reported on piggy-backing is the buffer that gets a real benefit when no nfb applied around it. Some years ago did some measurements and found rising distortion from increased levels up to 0.3% above 2VRMS. With hindsight (which is conveniently always perfect ), it was the buffer and not the transconductance front that caused this.
Not read every post, has anybody made any similar observation?
.
), it was the buffer and not the transconductance front that caused this.Not read every post, has anybody made any similar observation?
.
Wondering if the perceived improvement reported on piggy-backing is the buffer that gets a real benefit when no nfb applied around it. Some years ago did some measurements and found rising distortion from increased levels up to 0.3% above 2VRMS. With hindsight (which is conveniently always perfect
Not read every post, has anybody made any similar observation?
.
I think most people are not using the internal buffer of the ad844.
I tried triple stack a while back but using only the internal buffer of one chip. I found the sound become a bit hard (distorted?). But is suspected that 2 of three chips may be fake or they were from different factories.
I will give it another try with an external fet buffer connected to pin 5. I think I have got enough geniune ad844s this time.
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OPA1641
I run the rails at +15 and - 15 volts DC. I will be trying a discrete op amp solution in the next few days. Kind of curious to see how that may compare. The discrete's cost more then OPA627's. I got a small bonus from work. So decided it was worth getting them to try.
I run the rails at +15 and - 15 volts DC. I will be trying a discrete op amp solution in the next few days. Kind of curious to see how that may compare. The discrete's cost more then OPA627's. I got a small bonus from work. So decided it was worth getting them to try.
read back a few pages Joe, we've already done this, it's OK but the single (real) OPA627 eats it.
Cheers George