I was more interested in an equivalent part (equivalent specs) for a power amp for an 8 ohm load. The THD number are quite impressive...it was more an inquiry to see if national is coming out with power amplifiers that have nicer specs than the 3875/3886. You're right, that part certainly is not for driving direct load of a speaker...
Before this thread wanes...
While the LM4562 seems to be a promising part, I am disappointed by the (lack of) quality of the datasheet. Page after page of repetitive and redundant distortion graphs, most of them telling more about the noise floor of the combined DUT/tester than telling anything useful about the DUT. Who creates these thing? On top of this, example RIAA circuits that show that the author has never read Lipshitz's paper on the topic. Then there is the spec table that refers to the test circuit of "Figure X". Who edits these? Did anyone edit it?
I hope the part is better than the datasheet.
While the LM4562 seems to be a promising part, I am disappointed by the (lack of) quality of the datasheet. Page after page of repetitive and redundant distortion graphs, most of them telling more about the noise floor of the combined DUT/tester than telling anything useful about the DUT. Who creates these thing? On top of this, example RIAA circuits that show that the author has never read Lipshitz's paper on the topic. Then there is the spec table that refers to the test circuit of "Figure X". Who edits these? Did anyone edit it?
I hope the part is better than the datasheet.
BrianL said:
You raise a good point, and I submit to you I believe the part is better.
One thing that comes to mind is, if you look at most current parts and look back at early revisions of data sheets, you will notice that what you see now is very much better then what you would have seen when the part was introduced. This is true for other ICs too, not just opamps. Give it a couple revisions. This is a brand new part.
I have critically tested it in several circuits now, and can say I am very pleased. I will not say there is nothing better, as I have not heard everything, but I think you would be hard pressed to find its equal, especially when you consider the cost.
Cheers!
Russ
preiter said:
Dear Sir,
have you got an answer about this very interesting option?
I would like to power one with a SLA battery so I am very interested in a working schematic for single supply.
In my intention it would have to drive a 5kohm load acting as a unity gain buffer.
I wonder what will be the power consumption as well in order to select the Ah of the battery.
I would be extremely grateful if you or anyone else could give me some hints.
Thank you very much indeed.
Kind regards,
beppe
On driving capacitive lines
Some of you pros, can you give a bit more detail as to the limitations of this op-amp with driving capacitive loads? I am using this part (or will use it when the samples come) in a sallen-key post-dac filter. My feedback cap is 1nF, 10x larger than the 100pf limit in the spec sheet, but it of course is resistor coupled with a 10K (the spec sheet makes allowances for larger caps on the load as long as they are resistor coupled).
Also, the output line to the amp will have some small capacitance. So, given that these cpacitances are resistor-coupled, (not straight between the output and ground) what is the safe range of resistor and capacitor to use that will keep this amp within the '100pF' cap. load limit? Maybe there's a simple formula or rule of thumb for this.
Thanks for all of your valuable reccommendations and insights.
Some of you pros, can you give a bit more detail as to the limitations of this op-amp with driving capacitive loads? I am using this part (or will use it when the samples come) in a sallen-key post-dac filter. My feedback cap is 1nF, 10x larger than the 100pf limit in the spec sheet, but it of course is resistor coupled with a 10K (the spec sheet makes allowances for larger caps on the load as long as they are resistor coupled).
Also, the output line to the amp will have some small capacitance. So, given that these cpacitances are resistor-coupled, (not straight between the output and ground) what is the safe range of resistor and capacitor to use that will keep this amp within the '100pF' cap. load limit? Maybe there's a simple formula or rule of thumb for this.
Thanks for all of your valuable reccommendations and insights.
Group buy?
I ordered 2 samples of LM4562 in dip to replace OPA2134 in modded (CDM1) 304 mk2, but have to pay $17.48 shipping and handling costs!!
Isn't it time for a group buy, the large demands for this chip will problably assure the bulk buyer will sell them fast.
Btw have four 33uF Black Gate Nx caps awaiting to sit next to those LM4562's
I ordered 2 samples of LM4562 in dip to replace OPA2134 in modded (CDM1) 304 mk2, but have to pay $17.48 shipping and handling costs!!
Isn't it time for a group buy, the large demands for this chip will problably assure the bulk buyer will sell them fast.
Btw have four 33uF Black Gate Nx caps awaiting to sit next to those LM4562's
Re: Group buy?
On another topic:
*** Has anyone tried forcing the LM4562 into Class-A? ***
How does it sound? I have a Crown Macro reference amp that uses a quad in the front end using class-A mode. When the LM4564 becomes available next year I plan to use them. I want to know if I should take off the resistor going to the power rail, letting the op amp do what it wants.
In the states, Digikey lists LM4562, but the price is $5.50 for quantities under 25 dips, then drops over $1 for 25, and then almost another $1 for 100+. Unfortunately, quantity available is still zero. I figure I can use at least a dozen in surround sound processors/receivers, sound cards, dvd players etc. US sample pricing isn't so bad.tubee said:
On another topic:
*** Has anyone tried forcing the LM4562 into Class-A? ***
How does it sound? I have a Crown Macro reference amp that uses a quad in the front end using class-A mode. When the LM4564 becomes available next year I plan to use them. I want to know if I should take off the resistor going to the power rail, letting the op amp do what it wants.
Seen the popularity this chip is group-buy-ready.
Want to upgrade Kenwood tuner, Marantz surround amp and more.
Pulling an opamp in class A, done that some times (Ne5532). Did it with 2 transistors and 3 resistors in current source. The wanted current can be calculated. See this site for tips & tricks (scroll down)
Englisch: http://www.hawkaudio.nl/tips.htm
Dutch: http://audio.nl/tips.htm
Btw i've done allmost all those tricks, with excellent result.
Want to upgrade Kenwood tuner, Marantz surround amp and more.
Pulling an opamp in class A, done that some times (Ne5532). Did it with 2 transistors and 3 resistors in current source. The wanted current can be calculated. See this site for tips & tricks (scroll down)
Englisch: http://www.hawkaudio.nl/tips.htm
Dutch: http://audio.nl/tips.htm
Btw i've done allmost all those tricks, with excellent result.
ashok said:This one really needs a group buy.
Buy over 250 and we get it for $3.30 each .
We can possibly easily get enough people interested in 250 pieces totally. Beyond 250 pieces the drop in price is much less.
Company direct is less but the quantity might be 5000 pieces !!
There don't appear to be any MDIP available yet.
SMD, DIP, and metal can versions are all available. Most things are smd these days, that's all.
I destructively change smd op amps. Clip the leads then heat to remove any bits on the pads. The new one goes on easy. Hold with pincers/tweezers until the solder on the pad melts. For capacitors I use two irons simultaneously. I find changing smd parts easier than through-hole, especially on multi-layer boards.
I just did a sound card today. The opamp change was a breeze while upgrading the 10uf dc-blocking caps to black gates was painful due to small lead size on a 4-layer board. Hard to get all the solder out of the holes. I eventually prevailed! Pioneer DV47ai is next.
I destructively change smd op amps. Clip the leads then heat to remove any bits on the pads. The new one goes on easy. Hold with pincers/tweezers until the solder on the pad melts. For capacitors I use two irons simultaneously. I find changing smd parts easier than through-hole, especially on multi-layer boards.
I just did a sound card today. The opamp change was a breeze while upgrading the 10uf dc-blocking caps to black gates was painful due to small lead size on a 4-layer board. Hard to get all the solder out of the holes. I eventually prevailed! Pioneer DV47ai is next.
Hi markk02474
Yes thought it over too and that would be the best way: Don't keep the original chip but destroy it. Thanks for info.
Have a very small sort of knipex clip and will grind a fine point on the sides to get easy between the pins. When more then one pin is clipped, there is a risk of pulling and thus ripping the copper trace off.
Though hole is tougher then.
Btw i removed a SMD 16 pin 24 bit Cristal DAC without chip destroy: Put a small knife between trace and lead of chip, cut it off. The pcb will be destroyed then, not chip (Old DVD player) Some leads are some bended then but that can be corrected. Remove trace rests with soldering iron from chip leads (quickly or it will heat chip to much)
I was waiting for the LM4562 chip a long time, cheap and good. I don't understand OP627's pricing, if production costs are around few dollars, and i think it is, why does BB keeps price artificially high? For high end sakes? Or has the 627 heavy gold plated silver & laser trimmed leads within 1 thou.
Yes thought it over too and that would be the best way: Don't keep the original chip but destroy it. Thanks for info.
Have a very small sort of knipex clip and will grind a fine point on the sides to get easy between the pins. When more then one pin is clipped, there is a risk of pulling and thus ripping the copper trace off.
Though hole is tougher then.
Btw i removed a SMD 16 pin 24 bit Cristal DAC without chip destroy: Put a small knife between trace and lead of chip, cut it off. The pcb will be destroyed then, not chip (Old DVD player) Some leads are some bended then but that can be corrected. Remove trace rests with soldering iron from chip leads (quickly or it will heat chip to much)
I was waiting for the LM4562 chip a long time, cheap and good. I don't understand OP627's pricing, if production costs are around few dollars, and i think it is, why does BB keeps price artificially high? For high end sakes? Or has the 627 heavy gold plated silver & laser trimmed leads within 1 thou.
I just replaced a couple of smd OPA2134 chips on a UCD module replacing them with LM4562 smd. I managed to lift the OPA2134 chips without destroying them or the circuit board by pushing a safety pin between the legs of the chip and the circuit board, and as the pin is a little bigger than the legs to PCB clearance, as the lead is heated with the iron the pin pushes the lead up and off the board. I continue pushing the pin past all the legs to remove a side then do the same trick with the other side.
As well as saving the PCB, the pin also acts as a heat sink for the chip so that the heat does not destroy it. This removes the chip in seconds and both board & chip hardly gets hot.
I'll have to wait until the weekend to fire up the LM4562 to see how it sounds!
Regards,
Dean
As well as saving the PCB, the pin also acts as a heat sink for the chip so that the heat does not destroy it. This removes the chip in seconds and both board & chip hardly gets hot.
I'll have to wait until the weekend to fire up the LM4562 to see how it sounds!
Regards,
Dean
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