jaudio said:
Nope.
The y-scale on that diagram is dB gain, so a voltage gain of 30 = approx. 29.4 dB gain. If you see in the diagram the x-scale is logarithmic, which means it's flat up to about 27k or there about. (The log scale is weird in the diagram)
edit:
Used SplTrace to get a more accurate reading. Voltage gain of 30 gives approx 30k freq. With the recommended 1k-10k combo which gives a voltage gain of 11, the freq. is 100k.
Some here at the forum has said the graph is even worse in real life. (don't remember who)
jaudio said:
SplTrace tells me it's then flat to 50k. It's hard to read accurate this diagram without "cheating" with SplTrace.
26dB gain = 20 voltage gain
According to my calculations, you'd reach 80k with a voltage gain of 13. --> 1k and 12k resistors.
Lets us know how they look and sound once your trasnformer arrives 
😉
Keep up the good work Alcaid.
😉 Keep up the good work Alcaid.
hey i am a hobbyist i have the opa549. could u please send me a pcb layout diagram in black and white (jpg) and also the parts list and part names.
i am an extreme amateur i cant design my own circuits yet.
can u also tell me the specs of the is circuit
i am an extreme amateur i cant design my own circuits yet.
can u also tell me the specs of the is circuit
n00beR said:Lets us know how they look and sound once your trasnformer arrives
Keep up the good work Alcaid.
Well, the trafo arrived, and I've been listening to it for a couple of days.... SWEET! Love the sound of the amp+pre combo.
Onkyo amp for sale 😉
Alcaid said:
I've been reading this post, and want to build a 549 amp. I don't know why the gain matters though. Why can't I use a 22k resistor to not have a need for a preamp?
If I can't use the 22k resistor, I don't have a 10k resistor. I do have a 22k and a 1.8k or a 2.2k resistor. That would make either a gain of 13.2 or 11. Will that be the same as using a 10k and a 1k?
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Joined 2002
Alcaid, is there any chance you could post your pcb layouts to scale and in black&white?
That would be cool😎 Great work.
Steen.
That would be cool😎 Great work.
Steen.
soundNERD said:
If you use a higher gain the frequency response would roll off too early, and you would loose the top, and also people reports distortion in the midrange as a result.
I would use the 2k2 - 22k combo.
jleaman said:
Attached the Eagle files. Enjoy! 🙂
pdf files of the pre.
I made the top layer by just taping the layer before etching and used a 4mm drillbit to isolate the pins NOT going to the ground plane.
I made the top layer by just taping the layer before etching and used a 4mm drillbit to isolate the pins NOT going to the ground plane.
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