even if it's stating rev B parts and their values are different so I'm pretty sure buying rev C won't justify its cost compared to my own upgrade 😉
I see Hypex has a new datasheet on the OEM evaluation board. It confirms Richard's claims that the buffer circuit consumes up to 60mA. This would take the LM4562 right to the edge of self destruction at maximum output.
Here's what Richard said about the SIL-994:
"The 994Enh-Ticha can sink and source 150mA without breaking a sweat. 200mA and the THD at 1Khz goes from 0.0003 to about 0.0005. What this means is you can drive a very LOW IMPEDANCE. Which is what you have with this Hypex POWER AMP input."
Here's what Richard said about the SIL-994:
"The 994Enh-Ticha can sink and source 150mA without breaking a sweat. 200mA and the THD at 1Khz goes from 0.0003 to about 0.0005. What this means is you can drive a very LOW IMPEDANCE. Which is what you have with this Hypex POWER AMP input."
Last edited:
That's total current through the regs. Not just what's going through the op amp signal stage. And you have to get to crazy SPL levels (or have atrociously inefficient speakers) to be demanding a full signal voltage. Just play with the LTspice model to get a better idea of currents through the op amp.
not sure how did you calculated (edited) current values but typical output current of LM4562 is 26mA so current draw won't be much higher, if you check HxR datasheet it can deliver more than 100mA but you have to fight with heat dissipation
where did you take THD of 0003 under 150 or 200mA ?, these are values under RL=600ohm, there are no specs when RL=75ohm or Am I blind?
where did you take THD of 0003 under 150 or 200mA ?, these are values under RL=600ohm, there are no specs when RL=75ohm or Am I blind?
He is improperly looking at the max current through the regs and applying all of that to Isig and then arguing the LM4562 can't deliver the required current.
Richard told me that. I'm assuming he's aware of the capabilities of the product he built.
Why would seeing the performance with a 75 ohm load matter? 600 ohms is already double the 1200 ohm load of the NC-500's. The 0.0003% THD spec with 150mA load, is driving a 75 ohm load. I think that's a pretty good indicator of how powerful this opamp is. It's barely idling and running in pure class A driving the NC-500's.
If we look at the LM4562 data sheet, the comfortable operating range is 23-26mA. At 53mA it instantaneously short circuits. How could this be optimum for an application that requires up to 60mA current?
Last edited:
I see Hypex has a new datasheet on the OEM evaluation board. It confirms Richard's claims that the buffer circuit consumes up to 60mA. This would take the LM4562 right to the edge of self destruction at maximum output.
Here's what Richard said about the SIL-994:
"The 994Enh-Ticha can sink and source 150mA without breaking a sweat. 200mA and the THD at 1Khz goes from 0.0003 to about 0.0005. What this means is you can drive a very LOW IMPEDANCE. Which is what you have with this Hypex POWER AMP input."
An NDA breach for sure.
//
Actually after a closer look, the maximum recommended current capabilities of the LM4562 of 23mA is based on achieving good quality. 26mA is what it can handle if quality isn't of concern. Read #3 and 4:
Last edited:
You are confusing total max current through the regs with output current of the op amp. Btw remember also that the LM4562 is a dual...
it won't be more than 25mA otherwise Bruno would be crazy to accommodate it into evaluation board 😉
It's just an evaluation board. It works fine for the application. It says right on the datasheet that the buffer draws up to 60mA. Do you think they are lying?
😀 ok, one more time and slowly, 60mA is current draw of whole buffer board from DC regulators (not from source or opamp) to be able to operate, 26mA is current output of opamp towards hypex amp, got it? you are still mixing 2 things together 😉
Where are you getting the 26mA from? 60mA is the max current draw of the buffer. To find the max current draw of the NC-500 from the opamp, multiply the current draw from the regs by the efficiency of the opamp. To assume this is only 26mA is assuming the LM4562 is only 43% efficient.