Headphone my butt..
once I get something that I can build stable, I have the OPA541 prototype just sitting there waiting for some re-design. The headphone are basically from my brother - it would be neat for him to have something that he can just hook up to an output and it would drive his headphone. He works in broadcasting too, and there are balanced signals everywhere, but few portable headphone amps can use them.
once I get something that I can build stable, I have the OPA541 prototype just sitting there waiting for some re-design. The headphone are basically from my brother - it would be neat for him to have something that he can just hook up to an output and it would drive his headphone. He works in broadcasting too, and there are balanced signals everywhere, but few portable headphone amps can use them.
Do you remember?
I informed you that the sound got a bit worse when I increased the input resistor from 10k to 20k. I felt that the sound seemed to be suffering insufficient current supply from the booster. That was why I measured the amount of AC current flowing through the emitter resistor.
At last, I increased the ability of the AC current supply by reducing R15/16 from 22k to 11k. Hmm...the sound got better, without losing the clean square wave forms measured last time.
Now, I feel that the sound comes out more easier.
JH
I informed you that the sound got a bit worse when I increased the input resistor from 10k to 20k. I felt that the sound seemed to be suffering insufficient current supply from the booster. That was why I measured the amount of AC current flowing through the emitter resistor.
At last, I increased the ability of the AC current supply by reducing R15/16 from 22k to 11k. Hmm...the sound got better, without losing the clean square wave forms measured last time.
Now, I feel that the sound comes out more easier.
JH
Attachments
MSSCF
JH,
Did this change reduce the system gain, iow you now have to increase volume a bit to get the same loudness as before?
At any rate, you realise you throw away about 3dB of gain for nothing with that 20k-47k input attenuator, right?
Jan Didden
JH,
Did this change reduce the system gain, iow you now have to increase volume a bit to get the same loudness as before?
At any rate, you realise you throw away about 3dB of gain for nothing with that 20k-47k input attenuator, right?
Jan Didden
Bernhard said:
Do you mean the 100k R2 & R4 in JH's schematic (post #642) and all the X circuits?
If that's the one, read this:
http://www.passlabs.com/pdf/xa-white-paper.pdf
and this:
http://www.passlabs.com/pdf/susy.pdf
/Hugo - no way to find a better explanation 😉
Msscf
Yes, I increase the volume a bit. Anyhow, I have no problem with the loudness at all. The pre, BOSOZ, is set with about 10dB gain while this power amp has approximately 24dB on the balanced input mode.
No, with 20k-47k I get better and cleaner square wave measurement results with which I believe that the amp is stable.
JH
PS
The reduction of R15/16 to 11k affects the sound much. I am impressed on it. I want to have further experiment with further reduced R15/16 if it is possible without losing the stable square wave forms. But, at the moment the components around the girly-chips are arranged too compact to do that. Soon I will build one more baby. Then, I will have a chance of the further experiments. I am getting good music, real DIY enjoyment and useful lessons. 🙂
janneman said:
Yes, I increase the volume a bit. Anyhow, I have no problem with the loudness at all. The pre, BOSOZ, is set with about 10dB gain while this power amp has approximately 24dB on the balanced input mode.
No, with 20k-47k I get better and cleaner square wave measurement results with which I believe that the amp is stable.
JH
PS
The reduction of R15/16 to 11k affects the sound much. I am impressed on it. I want to have further experiment with further reduced R15/16 if it is possible without losing the stable square wave forms. But, at the moment the components around the girly-chips are arranged too compact to do that. Soon I will build one more baby. Then, I will have a chance of the further experiments. I am getting good music, real DIY enjoyment and useful lessons. 🙂
I thought it would be appropriate to ask if you would like this thread to be moved to a new forum for girly amps? 😉http://www.diyaudio.com/forums/forumdisplay.php?forumid=40
Peter Daniel said:
Sorry dude but there is nothing 'girly' about this amp...
And technically it's not a chip-amp either. In fact, since there are two semiconductor components it's a discrete design. 😉
On a separate note, there are way too many categories on this forum.
I think it is Nelson's to decide..
but in my mind, No.
Using the chips is not developed enough that a likely chip amper is ready to try it. When there are more than a couple of stable amps running, perhaps.
but in my mind, No.
Using the chips is not developed enough that a likely chip amper is ready to try it. When there are more than a couple of stable amps running, perhaps.
Peter Daniel said:
Well, actually, its mainly Nelson's thread.
This one's somewhere between the Chip and the Pass forum.
But if you ask me, I don't mind, as long as we can find it it's ok for me.
Or even better...you could create a "Fearless Amplifier Builders" forum.
😎 😉 /Hugo
grataku said:
I did not say it's a girly amp, I said this about the new forum. OTOH, I noticed JH was reffering to his amp (or part of it ) as "girly"😉
Re: Msscf
Understand. If you go even lower than 11k, and you start to get into instability country, you may want to parallel the resister with a couple of 10s of pF's.
Jan Didden
jh6you said:
Understand. If you go even lower than 11k, and you start to get into instability country, you may want to parallel the resister with a couple of 10s of pF's.
Jan Didden
Netlist said:
Or even better...you could create a "Fearless Amplifier Builders" forum.
/Hugo
Oh Yeah! 😎
I don't subscribe to "girly-man" chip circuits, but I do believe in catering to the interests of the DIY population.Netlist said:
Fearless Amplifier Builders. Brings to mind Fearless Vampire Hunters....
Me, I'm like Gomez Adams and his train set.
How long are the wires to the Mosfets allowed to be ?
Maybe my circuit is unstable because of too long wires ?
I have new changes that will help perhaps.
Also a new idea...
Tommyknockers, Tommyknockers knocking on my door 
Maybe my circuit is unstable because of too long wires ?
I have new changes that will help perhaps.
Also a new idea...
Tommyknockers, Tommyknockers knocking on my door
Nelson Pass said:
"In the show, Fester has an "Electric Personality" HE is able to conduct electricity through his body. This allows him to power some of his experiments, Gomez's train set, and of course, light a bulb in his mouth.
In reality, the actor portraying Fester would put a prop light bulb in his mouth. This prop had a small bulb powered by a small battery. There were two contacts on the bottom of the bulb. When pressed at the same time by the actors tongue, the contacts would completed a circuit to the low voltage bulb and light up. This method of using small contacts and body parts is used to power many different toys available on the market today."
Bernhard said:
As seen on your picture, this can't be the problem. Make sure the 220ohm resistors are as close as possible to the gates.
/Hugo
What is a foot converted to inches or centimeters ?
I put a circuit on the simsalabim.
The circuit has an output resistor of 100ohm.
It is fed by a 2V 1kHz sine.
Another sine is coupled to the output of the first circuit with an output resistor of 1k.
The result is that the output of the circuit is a 1k sine, 10% modulated with a 10k sine.
This 10% sine modulation fakes a distortion.
Now I connected a second circuit, and the modulation is nearly gone
This could lead to a ZDA / NDA.
I put a circuit on the simsalabim.
The circuit has an output resistor of 100ohm.
It is fed by a 2V 1kHz sine.
Another sine is coupled to the output of the first circuit with an output resistor of 1k.
The result is that the output of the circuit is a 1k sine, 10% modulated with a 10k sine.
This 10% sine modulation fakes a distortion.
Now I connected a second circuit, and the modulation is nearly gone
This could lead to a ZDA / NDA.
- Status
- Not open for further replies.