Digikey stocks adapters for some surface mount types (SOIC) to 8-pin DIPs: A724-ND (page 207 of current catalog). They cost $7 each in small quantities. They're delicate to solder to, but I've used them and they work well.
Some of the surface mounts are even smaller and won't fit on the SOIC -> DIP adapter.
Some of the surface mounts are even smaller and won't fit on the SOIC -> DIP adapter.
OPA627
I have tried many differend kinds of opamps for the output stage of my CDp, includind ad825, opa604 opa2132 BUT the opamp to go for is definitely OPA627 . By far the cleanest clearer, most dynamic and above all the one that creates a dramatic deep soundstage of unrealistic proportions. only valid alternative is the opa604 and ad825 maybe followed by the opa2132 which is dual(the only positive point about it). Just give opa627 an audition compared with others! Just the perfect opamp for hi-end cdp output stages as well as trully good line pre-amplifiers.
I have tried many differend kinds of opamps for the output stage of my CDp, includind ad825, opa604 opa2132 BUT the opamp to go for is definitely OPA627 . By far the cleanest clearer, most dynamic and above all the one that creates a dramatic deep soundstage of unrealistic proportions. only valid alternative is the opa604 and ad825 maybe followed by the opa2132 which is dual(the only positive point about it). Just give opa627 an audition compared with others! Just the perfect opamp for hi-end cdp output stages as well as trully good line pre-amplifiers.
I agree. The OPA627, when properly applied, is a certainly a top class performer.
That being said, many of the figures in the "Functional Description" section of the datasheet for the AD8610 contrast the AD8610 directly with the OPA627. suggesting the AD8610 may have been designed to be an "OPA627 killer".
I've ordered samples because I'm curious.
Michael
That being said, many of the figures in the "Functional Description" section of the datasheet for the AD8610 contrast the AD8610 directly with the OPA627. suggesting the AD8610 may have been designed to be an "OPA627 killer".
I've ordered samples because I'm curious.
Michael
Ive already got them .. I am planing to make a DAC where i buffer the dac with the ad8610.
Second stage making a attenuator around AD8610 and a WM8816 .. It is inverted so i will drive a following stage with a AD8610 followed by a discrete bufferstage...
I like its settling time to 0.001 in ~800nS ... Better than 16 bit in less than 800nS!!!!
YES it looks like a opa627 KILLER!!
OPA627 and the AD8610 are really good opamp's,but they will suffer a lot if they don't have a low noise low impedance powersupply ... And impedance matching between in+ and in-
Sonny
Second stage making a attenuator around AD8610 and a WM8816 .. It is inverted so i will drive a following stage with a AD8610 followed by a discrete bufferstage...
I like its settling time to 0.001 in ~800nS ... Better than 16 bit in less than 800nS!!!!
YES it looks like a opa627 KILLER!!
OPA627 and the AD8610 are really good opamp's,but they will suffer a lot if they don't have a low noise low impedance powersupply ... And impedance matching between in+ and in-
Sonny
Has anyone looked at OPA228/2228/4228?
Seems pretty impressive although I have not used it yet. The slew rate is somewhat meager, and it is optimized for gains > 5, but can be externally compensated for.
It is the same thing as it's brother, OPA227, except it has lower distortion on the high end, and has increased slew.
The same is true for the OPA134/132. They seem to be the same thing, but one has improved performance--particularly distortion.
Seems pretty impressive although I have not used it yet. The slew rate is somewhat meager, and it is optimized for gains > 5, but can be externally compensated for.
It is the same thing as it's brother, OPA227, except it has lower distortion on the high end, and has increased slew.
The same is true for the OPA134/132. They seem to be the same thing, but one has improved performance--particularly distortion.
rpell:
I would not bother biasing the OPA627 into Class A if I could add a current buffer behind it. I beleive a buffer is the best way to achieve the desired end result: keeping the op amp in class a mode. The output stage of most op amps is class a up to a point. The buffer eliminates the op amp ever driving a load past the point of class a operation. It also has the benefit of minimizing any thermal effects that would otherwise be caused by the output stage heating. The buffer also lets you use lower impedance feedback components to reduce noise and reduce impacts of parasitics.
There are lots of buffers to play with: BUF634, LM6321, BUF04, EL2001, etc. are a few that come to mind. You can also use the high powered current feedback amps as buffers; some part numbers are the AD811, AD815, OPA603.
And of course, you can always roll your own with discrete bipolars, JFETs or MOSFETs. I do this for one of my headphone amps and it sounds great.
Michael
I would not bother biasing the OPA627 into Class A if I could add a current buffer behind it. I beleive a buffer is the best way to achieve the desired end result: keeping the op amp in class a mode. The output stage of most op amps is class a up to a point. The buffer eliminates the op amp ever driving a load past the point of class a operation. It also has the benefit of minimizing any thermal effects that would otherwise be caused by the output stage heating. The buffer also lets you use lower impedance feedback components to reduce noise and reduce impacts of parasitics.
There are lots of buffers to play with: BUF634, LM6321, BUF04, EL2001, etc. are a few that come to mind. You can also use the high powered current feedback amps as buffers; some part numbers are the AD811, AD815, OPA603.
And of course, you can always roll your own with discrete bipolars, JFETs or MOSFETs. I do this for one of my headphone amps and it sounds great.
Michael
For those interested in opamp/buffer combinations, the headwize site is full of stuff on it: www.headwize.com
richt said:
Hi richt,
What comparisons have you made to come to this conclusion? Have you swapped surface mount components out with their dip or leaded version in the same circuit and compared how the sound changed? (Don't compare tantalum or electrolytics with poly caps and blame the difference on the surface mount).
Virtually all modern products use surface mount components. I doubt if you will see many newly designed opamps even available in dip form in the future.
Some of the reason for using surface mounts instead of leaded or dip packages include:
- Greatly reduced lead inductance which permits better high frequency performance. Chip caps do a much better bypassing job than leaded caps because of this.
- Much smaller footprint which permits reduced product size/cost.
- Lower packaging costs reduce component cost.
- Better heat transfer to circuit board.
- Simpler and better performing board layouts (leaded and dip parts require a hole drilled through all layers of the board for every pin of every device).
- Simpler PCB manufacturing. All surface mounts means you no longer require a wave solder step which puts less thermal stress on the board. Not having to go through the wave solder step also lets you put components on both sides of the board for even more compact designs.
I understand that surface mount parts are more difficult for hobbiest to use, but that has nothing to do with how well they perform. In the case of an opamp it's exactly the same silicone inside, it's just in a better package.
Phil
5 - 9 years ago it was a problem when going from DIP to SMD housing. Especially with Voltage Refence and Temperature sensor.
They where not made for SMD housing.
Today .... It is no problem. If it is a problem ... You have to check your PCBdesign. If you can hear differences your circuit is oscillating in one of your configurations. ... Weak supply? To long lines from bypass caps to VPOS and VNEG?
Regards
Sonny
They where not made for SMD housing.
Today .... It is no problem. If it is a problem ... You have to check your PCBdesign. If you can hear differences your circuit is oscillating in one of your configurations. ... Weak supply? To long lines from bypass caps to VPOS and VNEG?
Regards
Sonny
rpell,
If you could keep us posted, I'd be very interested in the progress with your headphone amplifier. I may someday build one like you're planning, I actually went so far as to buy the BUF634s but then went with a Class A MOSFET design instead (a modified Szekeres, if you're a HeadWizer). Mine was going to be derived from a circuit that Pete Millett posted there a while back (used OPA134/BUF634).
If you could keep us posted, I'd be very interested in the progress with your headphone amplifier. I may someday build one like you're planning, I actually went so far as to buy the BUF634s but then went with a Class A MOSFET design instead (a modified Szekeres, if you're a HeadWizer). Mine was going to be derived from a circuit that Pete Millett posted there a while back (used OPA134/BUF634).
hi
i completly disagree with surface mount !
first when an op amp blows it makes a beautifull hole in your pcb
destroying the traces ( mackie mixing boards & presonus preamps) making that channel unrepairable.
it is more suceptible to heat & moisture.
we rebuilt a blown channel sttrip burned with small pcbs & dip
op amps & small cables going to the blown area.
that particular channel was sounding a lot better than the original ones.
it makes your equipment less repairable & upgradable.
richt.
sorry.
i completly disagree with surface mount !
first when an op amp blows it makes a beautifull hole in your pcb
destroying the traces ( mackie mixing boards & presonus preamps) making that channel unrepairable.
it is more suceptible to heat & moisture.
we rebuilt a blown channel sttrip burned with small pcbs & dip
op amps & small cables going to the blown area.
that particular channel was sounding a lot better than the original ones.
it makes your equipment less repairable & upgradable.
richt.
sorry.
Hello all,
thanxalot for the input
. My interest is not into op-amps as an audio amplifier but I fervently need them as error amplifiers for shunt-regulated power supplies for tube amps. In this application the error amplifier's behaviour is VERY important and op-amps usable as audio amplifiers have proven to perfom very well.
I am surprised noone mentioned the AD797. A buddy of mine is modifying CD-players since before 1990 and he used the OPA627 as his all time favourite, until the AD797 was tried out. anyone out there knowing this thing? Having tried it out?
thanxalot for the input
. My interest is not into op-amps as an audio amplifier but I fervently need them as error amplifiers for shunt-regulated power supplies for tube amps. In this application the error amplifier's behaviour is VERY important and op-amps usable as audio amplifiers have proven to perfom very well.I am surprised noone mentioned the AD797. A buddy of mine is modifying CD-players since before 1990 and he used the OPA627 as his all time favourite, until the AD797 was tried out. anyone out there knowing this thing? Having tried it out?
Can't help with the AD797, but I'm getting my hands on some LT1358s next week to tweak on my bass guitar preamp. At 25 MHz GBW and 700 V/us slew (!), it's supposed to be stable into any capacitive load and very forgiving as long as you maintain some phase margin. Check out the data sheet, it's an eye opening design for a fast op amp.
The fastest in the series, the LT1363 through 1365, has some stout current driving capabilities (try 50 mA loads!) as well as 70 MHz GBW and 1000 V/us slew. All this at only 6 mA per amplifier - which is about what the 5532 draws, FYI. I'm thinking of using one for a headphone amp.
The fastest in the series, the LT1363 through 1365, has some stout current driving capabilities (try 50 mA loads!) as well as 70 MHz GBW and 1000 V/us slew. All this at only 6 mA per amplifier - which is about what the 5532 draws, FYI. I'm thinking of using one for a headphone amp.
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