Coud I use IRFP240 to replace IRF510 in this project? I think it is overkill, but I have plenty left.
If you are using your own layout: sure, pretty much any mosfet is on the table as long as you keep an eye on the gate charge. You want to keep that reasonably low, say below 100 nC (IRF510 is 8 nC). You can even use an n-channel device, if you flip the output stage on its head, so to speak.
If you are using the RJM Audio circuit boards: The IRFP240 is pin compatible, but the package is slightly bigger. TO-247 vs. TO-220. If you can get it to fit, by all means make the substitution.
http://www.vishay.com/docs/91210/91210.pdf
http://www.vishay.com/docs/91015/sihf510.pdf
/R
If you are using the RJM Audio circuit boards: The IRFP240 is pin compatible, but the package is slightly bigger. TO-247 vs. TO-220. If you can get it to fit, by all means make the substitution.
http://www.vishay.com/docs/91210/91210.pdf
http://www.vishay.com/docs/91015/sihf510.pdf
/R
Thank you! I change my option to IRFP240 to IRFP150 because I used LTSpice and found at 20khz the simulator run not so smooth (like something goes wrong) and result with IRFP150 show some reduce in THD, I'm not expect miracle about that but I already have the part so why not try. And yes, I will use my own layout.
I think with gain = x3.5, this headphone amp can work as a pre-amplifier just fine. Am I right?
Any advice about Stepped Volume Attenuator? I use 20K Alps Blue-Velvet audio/log taper volume control now and I need your personal impression of upgrade for Alps Potentiometer vs. Stepped Attenuator. Thank you.
I've always felt there was a big improvement moving to a stepped attenuator, but it is hard to pin down. Considering the cost difference isn't great (or doesn't have to be: you can build your own attenuator very cheaply), it always seemed to me to be a sure-fire upgrade.
Thank you since you gave me a confidence that I'm moving to the right direction....
Resistors are not a problem since I have access to Vishay-Dale RN55 (hope it is a good/right type for our headphone amp). Question is when to get nice 20+ stereo stepper...
Resistors are not a problem since I have access to Vishay-Dale RN55 (hope it is a good/right type for our headphone amp). Question is when to get nice 20+ stereo stepper...
Got it. It is so many there with doubtful quality, beside know hi-end brands and pricey once....
Can you please be more specific if possible.
Also, what type is the best: serial, leather or shunt?
Thank you.
Can you please be more specific if possible.
Also, what type is the best: serial, leather or shunt?
Thank you.
Got it. Thank you for advises.
I use recommended 20K Alps now, but my comfy zone of volume is about 7-8 in its scale of 10 (Max). Should I go for 10K or to stick to 20K for Attenuator?
In addition, what type do you guys recommend to use: series, leader or shunt?
I use recommended 20K Alps now, but my comfy zone of volume is about 7-8 in its scale of 10 (Max). Should I go for 10K or to stick to 20K for Attenuator?
In addition, what type do you guys recommend to use: series, leader or shunt?
10k or 20k isn't going to change the volume position, but if you need that setting then 10k is preferred.
It seems you need more gain, which is to say the headphone sensitivity is a bit low for the amp.
It seems you need more gain, which is to say the headphone sensitivity is a bit low for the amp.
I use AKG K701. How can I add more gain? Should I change voltage across R7 (it is 5.5V now).
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I'm surprised you need more gain with 62 ohm / 105 dB headphones like the '701s. Are you using a line-level source? The J-Mo II doesn't lend itself to easy adjustment of the circuit gain, so I'd suggest using a higher output source or a preamplifier.
/R
PS re. your earlier question about attenuator types: ladder, shunt etc there are no particular special considerations for this circuit as it is not sensitive to the input impedance. A regular shunt type is fine.
/R
PS re. your earlier question about attenuator types: ladder, shunt etc there are no particular special considerations for this circuit as it is not sensitive to the input impedance. A regular shunt type is fine.
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Yes, I connected CD player directly to your headphone amp. My payer is NAD M5 has 2V RMS, but it is MAX. So, I'll try to connect pre-amp in between. Lets see the results.
I tested.... So, I set my headphone volume potentiometer to MAX and pre-amp potentiometer was set to comfort zone which is found around 4 out of 10 scale. It definitely louder, but I feel that direct connection to CD player is kind of sounded clearer when its own potentiometer is set to 7 out of 10. I need to listen more to clarify that for sure. BTW, my pre-amp (for the reference) is TRV-4SE Limited: Triode Production - Triode Corporation
Unfortunately the preamp gain specification is reported as an input sensitivity of 250 mV, without knowing the reference output level I don't know the V/V gain.
A full 2 Vrms line level CD signal + 10 dB (6 Vrms!) of the J-MoII into K701 should not require the volume level to be set more than 50%. I would double check that R2 and R3 are set to the correct values. If you have some way to measure the gain, using a reference signal and an AC voltmeter, please check that it is 3x as expected.
/R
A full 2 Vrms line level CD signal + 10 dB (6 Vrms!) of the J-MoII into K701 should not require the volume level to be set more than 50%. I would double check that R2 and R3 are set to the correct values. If you have some way to measure the gain, using a reference signal and an AC voltmeter, please check that it is 3x as expected.
/R
My Triode TRV-4SE is Maranz 7c design (one to one, with smaller feedback. 82K is original, and TRV has 39K).
So, based on Maranz and 39K feedback resistor, my gain should be in 16-18 dB zone.
Le's go back to my original inquiries since we little deviated from the subject - potentiometer vs. attenuator…
In general note: I have no issue with your amp at all and it sounds amazing in my taste.
I also have no problem to use my Alps (20K) on scale 7. Attenuator might work better at that position, but I need to test that setup…
Now to go back to the subject’s details:
Does that amp is sensitive to the input impedance? If yes, then I’ll remove my Apls and I'll connect it directly to TRV pre-amp output.
If it is not sensitive , I’ll might use direct connection to CD and I’ll go to try 10K Attenuator with ladder assembly type.
One more detail... It is dead quite (absolute quite) when connected to CD. However, I have some little noise when connect it to TRV tube pre-amp.
So, based on Maranz and 39K feedback resistor, my gain should be in 16-18 dB zone.
Le's go back to my original inquiries since we little deviated from the subject - potentiometer vs. attenuator…
In general note: I have no issue with your amp at all and it sounds amazing in my taste.
I also have no problem to use my Alps (20K) on scale 7. Attenuator might work better at that position, but I need to test that setup…
Now to go back to the subject’s details:
Does that amp is sensitive to the input impedance? If yes, then I’ll remove my Apls and I'll connect it directly to TRV pre-amp output.
If it is not sensitive , I’ll might use direct connection to CD and I’ll go to try 10K Attenuator with ladder assembly type.
One more detail... It is dead quite (absolute quite) when connected to CD. However, I have some little noise when connect it to TRV tube pre-amp.
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