That's why my design (white/ gold) has the thermal pad underneath and vias connecting the top and bottom together (as per the datasheet).
That way its possible to apply a large soldering iron to the bottom, to melt the pre-placed solder on top, that's under the chip.
I have seen it done on a Youtube channel and it does work.
That way its possible to apply a large soldering iron to the bottom, to melt the pre-placed solder on top, that's under the chip.
I have seen it done on a Youtube channel and it does work.
Hi,
I'd have a question - I can't find although I've looked - where can I find that example you mentioned in which a 2sk17/2sj74 was swapped using an OPA828?
Replacing the 2SK170/2SJ74 pair for OPA828 is an interesting experiment. Choosing obsolete and hard to find parts that are also often counterfeit for DIY projects built by many is not really a strength.
Higher performance, normal availability and even lower cost. What is not to like?
Higher performance, normal availability and even lower cost. What is not to like?
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Not everything done during development was described in detail at some thread, but there are some details available.
Vunce replaced Toshiba input on his M2 build:
https://www.diyaudio.com/community/...it-and-similar-amplifiers.382345/post-6949371
https://www.diyaudio.com/community/...it-and-similar-amplifiers.382345/post-6948402
I've replaced Input on my LuDEF build:
https://www.diyaudio.com/community/...ludef-sissysit-and-similar-amplifiers.382345/
william2001 used it with SissySIT:
https://www.diyaudio.com/community/threads/sissysit-r-3.371272/post-7352277
There are other examples.
Thank you for the examples, I wasn't so much concerned with proving it was done as with how to safely replace the step from 2sk17/2sj74 with this OPA. I was thinking more of a schematic - how to do it. There are quite a few interesting designs on the mentioned j-fets.
Ah, I thought you were interested in confirmations that resulting sound is better or at least equal to the legendary Toshiba parts.
Unfortunately, operational amplifier can’t be a simple and direct replacement for JFET parts in any circuit. In all referenced examples, complete discrete JFET input buffer was bypassed and replaced with different version containing JFET opamp (and other required circuitry).
Unfortunately, operational amplifier can’t be a simple and direct replacement for JFET parts in any circuit. In all referenced examples, complete discrete JFET input buffer was bypassed and replaced with different version containing JFET opamp (and other required circuitry).
I can't find any source of VSOP adaptor with thermal pad and pins. any ideas? am currently using an adapter from mouser PA0042C for the opa2828, but no pad.
https://www.diyaudio.com/community/threads/opa828-opa2828-vs-opa627.400109/page-5#post-7735566
It has the to some incomprehensible pin 9.
It has the to some incomprehensible pin 9.
Its not incomprehensible - its for grounding the 0.1uF decouple caps which are an option and located on the same board as the OPA8282.
Op amps have +15v and -15v but no 0v center voltage, so this allows the + and - voltage to be decoupled.
Op amps have +15v and -15v but no 0v center voltage, so this allows the + and - voltage to be decoupled.
Of course I understand that. We had a discussion here and many did not understand "pin 9". I made some adapters in the past in similar style so with GND pin and 2 x cap. It is a good choice to do so, if not the best.
Hi,
Thank you for a thread 🙂
My question is regarding your experience with a power supply. Has anyone tried, what kind of capacitance is the best to power this OPAMP?
My OPA 2828 (double 828) will work as a buffer in my analog after DAC. They are supplied with 15VDC (LT1963/LT3015). Of course I am usying 100nf ceramic bypass, but what kind of Electrolytic is the best to use, in sense of Capacitance? 10 uF or rather 47 uF? Do you have experience with it?
Thank you for a thread 🙂
My question is regarding your experience with a power supply. Has anyone tried, what kind of capacitance is the best to power this OPAMP?
My OPA 2828 (double 828) will work as a buffer in my analog after DAC. They are supplied with 15VDC (LT1963/LT3015). Of course I am usying 100nf ceramic bypass, but what kind of Electrolytic is the best to use, in sense of Capacitance? 10 uF or rather 47 uF? Do you have experience with it?
Attachments
If you have a massiv ground plane nearby, maybe. If not, a single capacitor across the supply pins may be better than injecting a ground current where it is up to no good.
For my 4-way rebuilt crossovers that use the OPA2828's for the upper mid and high, I used an external dual R-core power supply which I converted to run -15/ +15v. It has big capacitors on it like 14,000uF, then I swapped the filtering caps on the crossover itself to new 2200uF/ 25v.
The custom made OPA828 boards also had the 0.1uF designed on with a spare 9th pin for a wire to the ground plane.
See here: