Hi,
I got another question, unrelated to my last one.
What do I have to do, to use the "Audio Out" on the ODAC and not the "Line Out"?
I want to try the ODAC with another Amplifier, thats why.
The amplifier is working, tested with an onboard soundcard, the ODAC is recognized in Windows and should be playing music, tested on different USB ports.
Is there a jumper or something that I am not aware of?
I got another question, unrelated to my last one.
What do I have to do, to use the "Audio Out" on the ODAC and not the "Line Out"?
I want to try the ODAC with another Amplifier, thats why.
The amplifier is working, tested with an onboard soundcard, the ODAC is recognized in Windows and should be playing music, tested on different USB ports.
Is there a jumper or something that I am not aware of?
You're sooooo funny Petting!
You get my vote for this site's best comedian.
ANY carbon film pot is subjective to channel imbalance issues at lower volume levels. To state that it's "isn't possible" is truly ludicrous.
I own several commercial integrated amps and preamps that use the RK27 and they ALL have channel imbalance issues at lower volume settings.
If those big, blue ALPS pots are so superior to stepped attenuators, then companies like Gold Point would've gone by the wayside years ago.
Yes, a Gold Point is considerably more expensive than an ALPS, but it'll outlast several ALPS and have zero issues with channel imbalances.
Ahh, another happy ALPS user without imbalance issues:
Need affordable stepped attenuator | Head-Fi.org
Not sure what in the hell "light shows and Laserdreams" have to do with this thread or HAs in general. It's totally meaningless and juvenile...but then so is your whole post above.
By the way, the name is Ammel, not Mel.
Now...let's bust out the moonshine and bunch of those good ole' NJM4556s and build a 02.
Just in case you missed it, most of the music you listen to probably already passed through dozens of opamps. That's what you're listening to, 5532s and the likes, and probably even some TL072s hahahaha!
No, I haven't missed anything. Personally, I could care less what the music has already passed through.
I DO care about what it passes through NOW, though.
Hahahaha! Thank you for such a funny post!
I'm afraid I have no idea on the ODAC. Hopefully someone who has experience of it can advise.
Hi everyone,
I'm about to order parts to build an O2 amp for desktop use only so I will omit the batteries. I'm also going to buy a bigger aluminium case and I will wire all the connectors and switches. I have a 12VAC 600mA power supply and I measured that even with 500mA output current to a resistive load the output voltage was around 13VAC.
I'd like to ask few questions before I make my order so I won't mess anything up.
I'm going to use Tasker C286 (or similar) to wire the volume pot, RCA-connectors ans 1/4" jack. I believe that's suitable wire for the job.
I was thinking that I would use a DP3T 3-position slide switch (Mouser 629-G128S3011) to control gain. My idea was that in position 1 there is no connection to ground and gain would be 1x. In positions 2 and 3 signal would go through resistors R17/R21 or R19/R23 to ground and that way I would get three position gain control. Is this a good idea? Does the swith quality matter? Can I use six (or five) single conductor hook up wires (like awg20 or awg22) and twist them together or should I use a shielded wire?
I know the D7 Led can't be changed to another color. If I still wanted to use e.g. a green power led separate from the PS-circuit, how do I do this correctly? Can I just connect the led and a resistor between the ~+12v line and ground line right after the power switch? If I do this should I use a equal load between ~-12v line and ground? Does this make any difference? Please let me know if this is a bad idea.
I was also thinking if I could fit tiny heat sinks to the voltage regulators (see Mouser 567-274-2AB). I was thinking if I could fit these to the regulators, if I don't mount the regulators so close to the pcb and bend the legs a bit. Thoughts?
I'm about to order parts to build an O2 amp for desktop use only so I will omit the batteries. I'm also going to buy a bigger aluminium case and I will wire all the connectors and switches. I have a 12VAC 600mA power supply and I measured that even with 500mA output current to a resistive load the output voltage was around 13VAC.
I'd like to ask few questions before I make my order so I won't mess anything up.
I'm going to use Tasker C286 (or similar) to wire the volume pot, RCA-connectors ans 1/4" jack. I believe that's suitable wire for the job.
I was thinking that I would use a DP3T 3-position slide switch (Mouser 629-G128S3011) to control gain. My idea was that in position 1 there is no connection to ground and gain would be 1x. In positions 2 and 3 signal would go through resistors R17/R21 or R19/R23 to ground and that way I would get three position gain control. Is this a good idea? Does the swith quality matter? Can I use six (or five) single conductor hook up wires (like awg20 or awg22) and twist them together or should I use a shielded wire?
I know the D7 Led can't be changed to another color. If I still wanted to use e.g. a green power led separate from the PS-circuit, how do I do this correctly? Can I just connect the led and a resistor between the ~+12v line and ground line right after the power switch? If I do this should I use a equal load between ~-12v line and ground? Does this make any difference? Please let me know if this is a bad idea.
I was also thinking if I could fit tiny heat sinks to the voltage regulators (see Mouser 567-274-2AB). I was thinking if I could fit these to the regulators, if I don't mount the regulators so close to the pcb and bend the legs a bit. Thoughts?
The LED can be changed... in fact tying the design to specific parts is not good practice. If you want a brighter power on LED then just reduce the value of R6.
You need to read my notes on fault-finding the 02 (link at the bottom of post #1) where I suggest a method to allow different LED's to be used but if your mains only then it doesn't really matter as long as the comparators are in the 'on' state.
You shouldn't need heat sinks as the current draw is so low.
The gain switch is important because it is in the audio path, however it is configured around the 'earthy' end of the chain and so a short run of single core wire should be fine.
You need to read my notes on fault-finding the 02 (link at the bottom of post #1) where I suggest a method to allow different LED's to be used but if your mains only then it doesn't really matter as long as the comparators are in the 'on' state.
You shouldn't need heat sinks as the current draw is so low.
The gain switch is important because it is in the audio path, however it is configured around the 'earthy' end of the chain and so a short run of single core wire should be fine.
The tip of a 3.5mm plug is normally left channel and so that would indicate pin 3 of P2 is left (going off the diagram and assuming its drawn correctly).
That would mean pin 1 of P1 is left input.
Two ground pins simply reinforces the ground connection. Is it an admission that one pin may be suspect in itself...... ideally all connections should be soldered imo apart from where you must have plugs/sockets such as the headphones and inputs.
That would mean pin 1 of P1 is left input.
Two ground pins simply reinforces the ground connection. Is it an admission that one pin may be suspect in itself...... ideally all connections should be soldered imo apart from where you must have plugs/sockets such as the headphones and inputs.
From what I can see, the MV5764.MP4B has been unavailable at all the major distributors for many months now. After all these years of experimentation among countless builders, is anyone aware of a suitable alternative in this list that is a close enough drop-in replacement which closely approximates the Objective2's requirement of Vf = 1.8Vdc at 0.5 mA?
Red 3 mm Through Hole LED Circuit Board Indicators | Mouser
Red 3 mm Through Hole LED Circuit Board Indicators | Mouser
I have read it and the associated post #3775. Note post #3775 which it references from post #1 should navigate to post #3775 but the link in post #1 is broken, likely due to a somewhat recent forum upgrade. However, I was able to track it down so here is the fixed link for everyone.
The Objective2 (O2) Headphone Amp DIY Project
However, both posts fail to answer my question: is there a direct LED drop-in replacement or replacements (part or parts with an identical Vf curve) found by any user after all these years? Certainly, many people can go through the exercise of multimeter testing to find the appropriate resistance value to use with any old LED, which I am already fully aware of having built several O2’s over the years. However, some people may not have ready access to a supply of assorted resistor values or want to wait for mail delivery again for a multiturn preset.
The ideal, simplified scenario here going forward would be a drop-in replacement or replacement(s). I am certain not everyone wants to start installing a multiturn preset on account of MV5764.MP4B now only being available in volume purchases (>=5000 at Mouser, >=125 at Arrow, >=75 at Future Electronics). Perhaps @agdr has found an LED that is a match? Alternatively, I would be willing, with your permission, to organize a group buy. At the current unit price of $.1480, an order of 75 of MV5764.MP4B at Future Electronics would come to around $11.10 plus shipping which is not bad all considered. LTL Group, who is a bit off the beaten path but is US-based and appears to be legitimate, also has 977 in stock at the moment:
Part Detail - LTL Group
MV5764MP4B Stock Status
The Objective2 (O2) Headphone Amp DIY Project
However, both posts fail to answer my question: is there a direct LED drop-in replacement or replacements (part or parts with an identical Vf curve) found by any user after all these years? Certainly, many people can go through the exercise of multimeter testing to find the appropriate resistance value to use with any old LED, which I am already fully aware of having built several O2’s over the years. However, some people may not have ready access to a supply of assorted resistor values or want to wait for mail delivery again for a multiturn preset.
The ideal, simplified scenario here going forward would be a drop-in replacement or replacement(s). I am certain not everyone wants to start installing a multiturn preset on account of MV5764.MP4B now only being available in volume purchases (>=5000 at Mouser, >=125 at Arrow, >=75 at Future Electronics). Perhaps @agdr has found an LED that is a match? Alternatively, I would be willing, with your permission, to organize a group buy. At the current unit price of $.1480, an order of 75 of MV5764.MP4B at Future Electronics would come to around $11.10 plus shipping which is not bad all considered. LTL Group, who is a bit off the beaten path but is US-based and appears to be legitimate, also has 977 in stock at the moment:
Part Detail - LTL Group
MV5764MP4B Stock Status
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Farnell's list is pretty generous with equivalents, unless I'm looking to the wrong specs: http://uk.farnell.com/w/c/optoelect...v|2.1v|2v&sort=P_ATT_BASE_VALUE_1000024_EN_GB.
Also, this one seems to have similar specs, just much brighter:
6321F7 VCC | Mouser Europe.
Anyway, I believe Mooly was referring to post #3775 indeed, like sonichedgehog36 said: The Objective2 (O2) Headphone Amp DIY Project, short copy-paste below:
"2) Accurate test of comparator. The comparators change state when the voltage on pin 2 of U2 falls BELOW the voltage across the LED. In other words if there is 2.00 volts on the LED, the rails will cut off when pin 2 falls below 2.00 volts. Replacing R9 with a 47k multiturn preset allows different LED's to used and the trip point to be adjusted accurately by monitoring the combined battery voltage and setting the preset to cut off when the combined battery voltage falls to say to 14 volts (two 8.2 volt batteries containing 7 cells each and discharging to 1 volt per cell)."
I'm gonna paste designer's text too:
"POWER LED: You might think this doesn’t need a mention but there are some special requriements. First, the normal forward current for most LEDs is 20 mA. That’s as much power as the entire rest of the amplifier needs! So a 20 mA LED would cut the battery life in half. The O2 uses a “HE” high efficiency red LED that is sufficiently visible with only about 0.5 mA. Second, it’s powered symmetrically from the rails (18 – 24 V) on purpose even if that seems less efficient. Otherwise one battery will drain slightly faster than the other. That gets you nothing except mismatched batteries. Finally, the LED’s forward voltage is a critical element of the power management circuit. You can’t change to a different color (especially white or blue) without making other changes as that will require more current and the different forward voltage means the power management circuit has to be altered."
Hope this helps,
Raul.
Also, this one seems to have similar specs, just much brighter:
6321F7 VCC | Mouser Europe.
Anyway, I believe Mooly was referring to post #3775 indeed, like sonichedgehog36 said: The Objective2 (O2) Headphone Amp DIY Project, short copy-paste below:
"2) Accurate test of comparator. The comparators change state when the voltage on pin 2 of U2 falls BELOW the voltage across the LED. In other words if there is 2.00 volts on the LED, the rails will cut off when pin 2 falls below 2.00 volts. Replacing R9 with a 47k multiturn preset allows different LED's to used and the trip point to be adjusted accurately by monitoring the combined battery voltage and setting the preset to cut off when the combined battery voltage falls to say to 14 volts (two 8.2 volt batteries containing 7 cells each and discharging to 1 volt per cell)."
I'm gonna paste designer's text too:
"POWER LED: You might think this doesn’t need a mention but there are some special requriements. First, the normal forward current for most LEDs is 20 mA. That’s as much power as the entire rest of the amplifier needs! So a 20 mA LED would cut the battery life in half. The O2 uses a “HE” high efficiency red LED that is sufficiently visible with only about 0.5 mA. Second, it’s powered symmetrically from the rails (18 – 24 V) on purpose even if that seems less efficient. Otherwise one battery will drain slightly faster than the other. That gets you nothing except mismatched batteries. Finally, the LED’s forward voltage is a critical element of the power management circuit. You can’t change to a different color (especially white or blue) without making other changes as that will require more current and the different forward voltage means the power management circuit has to be altered."
Hope this helps,
Raul.
Thanks! I think I will go ahead and just purchase from LDL Group when I hear word back from them on Monday. I am also planning on using all the recommended parts in AGDR's Objective2 upgrades guide here:
O2 upgrades
I have question concerning the section "O2 BOM V1.1 C13 & C14. Coupling capacitors" in that guide, which reads:
Upgraded part replacement = Mouser #505-MKS23.3/63/5 for $2.99 each vs. $0.86 for the original BOM part. These two capacitors are the coupling caps in the middle of the signal path of the O2. The new caps upgrade the BOM's 2.2uF to 3.3uF to extend the O2's low end frequency response roll-off from 1.8Hz to 1.2Hz. The new capacitors are the same physical size as the older capacitors in the O2 BOM and are the same DC and AC voltage rating. Still stacked film to have a minimal impact on the sound. The new caps are 5% tolerance vs. 10% for the BOM cap to provide better channel to channel matching.
Would a 50 VDC, 5% tolerance, 4.7 uF capacitor of the same dimensions and product family--more specifically, MKS2B044701K00JSSD, linked below--also work?
MKS2B044701K00JSSD WIMA | Mouser
O2 upgrades
I have question concerning the section "O2 BOM V1.1 C13 & C14. Coupling capacitors" in that guide, which reads:
Upgraded part replacement = Mouser #505-MKS23.3/63/5 for $2.99 each vs. $0.86 for the original BOM part. These two capacitors are the coupling caps in the middle of the signal path of the O2. The new caps upgrade the BOM's 2.2uF to 3.3uF to extend the O2's low end frequency response roll-off from 1.8Hz to 1.2Hz. The new capacitors are the same physical size as the older capacitors in the O2 BOM and are the same DC and AC voltage rating. Still stacked film to have a minimal impact on the sound. The new caps are 5% tolerance vs. 10% for the BOM cap to provide better channel to channel matching.
Would a 50 VDC, 5% tolerance, 4.7 uF capacitor of the same dimensions and product family--more specifically, MKS2B044701K00JSSD, linked below--also work?
MKS2B044701K00JSSD WIMA | Mouser
The higher capacitance would just lower the roll-off frequency even further, which isn't really necessary, given it's already low value. And the tolerance won't really matter since you wouldn't possibly hear any difference in the resulting ever so slightly roll-off frequency variation. I would just stick to the BOM's value, or, for what it is worth, to agdr's suggested upgrade, but IMHO that "upgrade" isn't really one other that at a component quality level, maybe...
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But would using the 50 VDC part I suggested, not being the higher 63 VDC rating, cause any problems? ADGR's part recommendation is out of stock which is why I asked.
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Oh well, I am kind of dumb.
After inquiring at Headnhifi, where i got all my parts, i was told, that there are two jumpers at the bottom of the ODAC, where you have to shorten them.
I just did not know, that these were jumpers.
Just in case anyone is wondering the same and stumbles upon my question.
After inquiring at Headnhifi, where i got all my parts, i was told, that there are two jumpers at the bottom of the ODAC, where you have to shorten them.
I just did not know, that these were jumpers.
Just in case anyone is wondering the same and stumbles upon my question.
Hi,
I got another question, unrelated to my last one.
What do I have to do, to use the "Audio Out" on the ODAC and not the "Line Out"?
I want to try the ODAC with another Amplifier, thats why.
The amplifier is working, tested with an onboard soundcard, the ODAC is recognized in Windows and should be playing music, tested on different USB ports.
Is there a jumper or something that I am not aware of?
Check this out: http://www.jdslabs.com/pdf/Custom O2-ODAC - Complete Soldering Guide.pdf
If I remember correctly, my ODAC has a switch that switches between Line-Out and Audio-Out, so I can choose between Objective2 and my external amplifier.
Oh well, I am kind of dumb.
After inquiring at Headnhifi, where i got all my parts, i was told, that there are two jumpers at the bottom of the ODAC, where you have to shorten them.
I just did not know, that these were jumpers.
Just in case anyone is wondering the same and stumbles upon my question.
I don't remember any jumpers on the bottom of the PCB, the're not enough place for jumpers I guess... However, what was this about? What would suppose to do these jumpers anyway?