I do not know if this helps you?
Long time ago german Burmester used the LT1028 in parallel to get a high perfomance phonostage. And if i remember right they got a pretty good test in StereoPlay in the 90's?
I do not think they are make parts who performance less than other manufactures from datasheet point of view. But i have never got to the point to try them out.
I think the reason why they are rejected is their low supplyvoltage (+/-5V). Every thing else is as good as any other manufacture from the Datasheet point of View..
A little warning. Rail-Rail input opamps makes crossover distortion at the inputs (+in and -in).. Why? In the same way as a class AB output stage. When you get near the rails one of the inputpairs will turn off and therefor there will be no bias current flowing through the inputstage from this pair. This is usual a fast turn off....
Thats what my note from a AD seminar says but i have to Go through them again.
Sonny
Long time ago german Burmester used the LT1028 in parallel to get a high perfomance phonostage. And if i remember right they got a pretty good test in StereoPlay in the 90's?
I do not think they are make parts who performance less than other manufactures from datasheet point of view. But i have never got to the point to try them out.
I think the reason why they are rejected is their low supplyvoltage (+/-5V). Every thing else is as good as any other manufacture from the Datasheet point of View..
A little warning. Rail-Rail input opamps makes crossover distortion at the inputs (+in and -in).. Why? In the same way as a class AB output stage. When you get near the rails one of the inputpairs will turn off and therefor there will be no bias current flowing through the inputstage from this pair. This is usual a fast turn off....
Thats what my note from a AD seminar says but i have to Go through them again.
Sonny
Bernhard,
I used the new Analog Devices AD8610 op amp(http://products.analog.com/products/info.asp?product=AD8610) in a 2-way Linkwitz-Riley X/O, using the schematic found at ESP Projects: http://sound.westhost.com/project09.htm
Everywhere you see an op-amp I used an AD8610: 6 per channel (including gain output for lows). The entire stereo unit is double-sided pcb, using all surface mount components. It is approximately 2 x 3 inches and includes dual regulators for each channel with a smt-fused flat-pack style transformer.
Instead of the values listed, I used 15K/30K resistors and 0.1 microfarad caps, giving a crossover frequency of 75 Hz. The unit performs really well and is absolutely quiet; it looks good on the oscilloscope too. I use the X/O in a system to match up a pair of Quad 988 and 12" Velodyne subs. The internal X/O in the Velodyne never mated well with the Quads; the new X/O is simply seemless.
Good luck,
Robert
I used the new Analog Devices AD8610 op amp(http://products.analog.com/products/info.asp?product=AD8610) in a 2-way Linkwitz-Riley X/O, using the schematic found at ESP Projects: http://sound.westhost.com/project09.htm
Everywhere you see an op-amp I used an AD8610: 6 per channel (including gain output for lows). The entire stereo unit is double-sided pcb, using all surface mount components. It is approximately 2 x 3 inches and includes dual regulators for each channel with a smt-fused flat-pack style transformer.
Instead of the values listed, I used 15K/30K resistors and 0.1 microfarad caps, giving a crossover frequency of 75 Hz. The unit performs really well and is absolutely quiet; it looks good on the oscilloscope too. I use the X/O in a system to match up a pair of Quad 988 and 12" Velodyne subs. The internal X/O in the Velodyne never mated well with the Quads; the new X/O is simply seemless.
Good luck,
Robert
Carlos,
I didn't replace anything. Your question seems to suggest that I took a X/O board and removed parts and soldered in soic devices.
Instead, I laid out my own pcb using only smt devices (soic, etc). That's how I fit a 4th order X/O with bass gain (and a volume control), in stereo, with a transformer, on such a small board.
Robert
I didn't replace anything. Your question seems to suggest that I took a X/O board and removed parts and soldered in soic devices.
Instead, I laid out my own pcb using only smt devices (soic, etc). That's how I fit a 4th order X/O with bass gain (and a volume control), in stereo, with a transformer, on such a small board.
Robert
new opamp adapters
For all you fans of the AD8610 and AD825 opamps, a dual AD8610 with altered specs should be out eventually, called the AD8620. No word on a dual AD825. However, there is another solution to the usability issue coming out in a week or so.
BrownDog makes SO8 to DIP adapters, among other things. They are really nifty for prototyping and replacement of legacy DIP components in existing circuits. I approached BrownDog with the idea and design for a new adapter which configures two SO8 opamps (one on top and one on the underside in mirror image superimposition) as a dual DIP opamp.
BrownDog loved it, and in about a week the first units should be in from the boardhouse. Both the original and the opamp adapter are $2.39 with a minimum order of 5. I have no financial stake in this, I'm just doing the DIYAudio community a service.
Here is a link to the BrownDog page:
http://www.brndog.com/SMTAdapt.html
For all you fans of the AD8610 and AD825 opamps, a dual AD8610 with altered specs should be out eventually, called the AD8620. No word on a dual AD825. However, there is another solution to the usability issue coming out in a week or so.
An externally hosted image should be here but it was not working when we last tested it.
BrownDog makes SO8 to DIP adapters, among other things. They are really nifty for prototyping and replacement of legacy DIP components in existing circuits. I approached BrownDog with the idea and design for a new adapter which configures two SO8 opamps (one on top and one on the underside in mirror image superimposition) as a dual DIP opamp.
An externally hosted image should be here but it was not working when we last tested it.
BrownDog loved it, and in about a week the first units should be in from the boardhouse. Both the original and the opamp adapter are $2.39 with a minimum order of 5. I have no financial stake in this, I'm just doing the DIYAudio community a service.
Here is a link to the BrownDog page:
http://www.brndog.com/SMTAdapt.html
Sorry, the bypass caps need to go in your circuit. There is no room to put pads and caps on the adapter and keep it the same size as an 8-pin DIP. You could always buy LC Audio AD825 modules at $25 a pop. Unfortunately, they are huge, and require a grounding tether from the adapter to the main pcb:
http://www.lcaudio.com/ad825.htm
The idea here is to have an adapter that fits anywhere a DIP would fit. If your circuit has bypass caps next to the DIP socket power pins, that should be close enough, certainly closer than the top opamp on the LC audio module is to its onboard bypass caps. We thought long and hard about that issue before committing to making the adapters as they are. Not all opamps even need bypass caps. If you purchased a hypothetical dual DIP AD825 it would not come with bypass caps on it, you would have to make arrangements for them. Thus it is so with the BrownDog adapter.
http://www.lcaudio.com/ad825.htm
The idea here is to have an adapter that fits anywhere a DIP would fit. If your circuit has bypass caps next to the DIP socket power pins, that should be close enough, certainly closer than the top opamp on the LC audio module is to its onboard bypass caps. We thought long and hard about that issue before committing to making the adapters as they are. Not all opamps even need bypass caps. If you purchased a hypothetical dual DIP AD825 it would not come with bypass caps on it, you would have to make arrangements for them. Thus it is so with the BrownDog adapter.
Sockets
As stated in another post:
Many modern high-speed op-amps can become unstable due to the increased parasitic capacitance introduced by ic sockets. It is best to keep these devices as close to the ground plane as possible. If interchangability is a must, it is usually recommended that pin racks be used.
Also it is power supply decoupling caps that I was refering to. On a two layer board they could go on the bottom and would also require a pad to solder a ground return lead to the main pcb. Also, all op amps require power supply decoupling capacitors. Go read the data sheet for your favorite op amp.
H.H.
As stated in another post:
Many modern high-speed op-amps can become unstable due to the increased parasitic capacitance introduced by ic sockets. It is best to keep these devices as close to the ground plane as possible. If interchangability is a must, it is usually recommended that pin racks be used.
Also it is power supply decoupling caps that I was refering to. On a two layer board they could go on the bottom and would also require a pad to solder a ground return lead to the main pcb. Also, all op amps require power supply decoupling capacitors. Go read the data sheet for your favorite op amp.
H.H.
I have used those adaptors to adapt SOIC devices to Dip packages with both the AD-8610 and the AD-825 without any bypasses on the adaptor just plug them into the Exsisting Dip sockets on the Board so we have adaptor plus on board sockets. as Unwise as this may seem i have never encounterd a stability pr overshoot problem doing this with the above mentioned opamps. Now Opamps with less phase margin or Higher bandwidth might be a Problem, But not with the AD-825 and AD-8610.
Sorry if there was confusion, bypass = decoupling to me, and the Analog Devices pdf datasheet refers to them as bypass caps.
I know the mantra regarding parasitic capacitance. Bypass/decoupling caps placed at the DIP socket should be close enough. I find it hard to believe a circuit would oscillate with the caps wired close to the DIP socket and not oscillate with the caps wired to the pins of the adapter. Use the nicely machined gold plated 4 way split tulip DIP sockets instead of the cheesey tin spring clip sockets and worry not.
There is not much incentive to muck around with soldering single SO8 OPA132 packages to an adapter when you could be using a better opamp or the dual DIP OPA2132 version instead. You would get thermal isolation between channels. Perhaps that is worthwhile for some applications.
I know the mantra regarding parasitic capacitance. Bypass/decoupling caps placed at the DIP socket should be close enough. I find it hard to believe a circuit would oscillate with the caps wired close to the DIP socket and not oscillate with the caps wired to the pins of the adapter. Use the nicely machined gold plated 4 way split tulip DIP sockets instead of the cheesey tin spring clip sockets and worry not.
There is not much incentive to muck around with soldering single SO8 OPA132 packages to an adapter when you could be using a better opamp or the dual DIP OPA2132 version instead. You would get thermal isolation between channels. Perhaps that is worthwhile for some applications.
Have you seen the new AD8065 preliminary specs? It is supposed to be out this month. New FastFET XFCB technology, 150MHz BW, 180V/µS slew rate, 5-24V supply, 6.5mA quiescent current, 30mA output current, 7nV/sqrtHz noise, rail to rail output, settling time to be determined. Could be interesting.
morsel said:Sorry if there was confusion, bypass = decoupling to me, and the Analog Devices pdf datasheet refers to them as bypass caps.
I know the mantra regarding parasitic capacitance. Bypass/decoupling caps placed at the DIP socket should be close enough. I find it hard to believe a circuit would oscillate with the caps wired close to the DIP socket and not oscillate with the caps wired to the pins of the adapter. Use the nicely machined gold plated 4 way split tulip DIP sockets instead of the cheesey tin spring clip sockets and worry not.
There is not much incentive to muck around with soldering single SO8 OPA132 packages to an adapter when you could be using a better opamp or the dual DIP OPA2132 version instead. You would get thermal isolation between channels. Perhaps that is worthwhile for some applications.
I agree. WRT 132 v 2132, what about electrical isolation and crosstalk?
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