I've just finished soldering every thing, and the first test fails. I'm only geting 7.5v across the batteries. I tried switching it on to see if the LED works and it came on. I switched it off right away but it took around 10 seconds for it to go dim again. I'm guessing one of the capacitors are keeping the charge? Any ideas?
Do I follow the power input with the DIMM and see where it starts to drop?
Do I follow the power input with the DIMM and see where it starts to drop?
Here's what I posted at Head-Fi for a starter subjective review of my O2.
OK here is a quick subjective comparison. O2 vs mildly modded Crack with Speedball.
Source = PC-> Foobar-> Wasapi-> AMB Gamma 2
Cans= HD595
Tunes+ Vince Guaraldi , A Charlie Brown Christmas, Fur Elise, The Christmas Song, Greensleeves
Had the wife help out. She would change the amps while my back was turned and start the song. I could tell the difference clearly, the Crack was smoother with more seeming detail, wider sound. The sound was kinda towards the rear and spread beyond the outside sides of the headphones. The instruments seemed to be a bit more clearly defined in the space. Bass was full and clear, mids good and cymbals and brushes were smooth and crisp. O2 did really well though, crisp sound, a bit forward and closed in, the sound was confined to my head. Definition was very good bass was deep and well defined but not as rich, mids good, cymbals and brushes were not as lush(?) and brighter.
Overall the O2 did a remarkably good job, it was fun to build, a great price and sounds very good. I mean the 6NS7 chrome top cost more than two boards and all the parts for two O2s... not to shabby!
Pardon my lack of description, my very first review of this type.
OK here is a quick subjective comparison. O2 vs mildly modded Crack with Speedball.
Source = PC-> Foobar-> Wasapi-> AMB Gamma 2
Cans= HD595
Tunes+ Vince Guaraldi , A Charlie Brown Christmas, Fur Elise, The Christmas Song, Greensleeves
Had the wife help out. She would change the amps while my back was turned and start the song. I could tell the difference clearly, the Crack was smoother with more seeming detail, wider sound. The sound was kinda towards the rear and spread beyond the outside sides of the headphones. The instruments seemed to be a bit more clearly defined in the space. Bass was full and clear, mids good and cymbals and brushes were smooth and crisp. O2 did really well though, crisp sound, a bit forward and closed in, the sound was confined to my head. Definition was very good bass was deep and well defined but not as rich, mids good, cymbals and brushes were not as lush(?) and brighter.
Overall the O2 did a remarkably good job, it was fun to build, a great price and sounds very good. I mean the 6NS7 chrome top cost more than two boards and all the parts for two O2s... not to shabby!
Pardon my lack of description, my very first review of this type.
@billyk,
I'm not surprised by your findings. I was playing around with my DAW (Adobe Audition, in this case) a few months back and found that if I introduce very small amounts of delay or overlay delay at different frequencies that I could push the sound outside my headphones. It was fantastic and I think it's the kind of trick I'd like to employ for some recordings.
What I'm telling you is that your tube amp has very likely introduced distortion so that there is a fractional time delay on one channel. It may also be something else, but my experience tells me that time delays are the way to make things 3D. I hope you enjoy it. I'm mature enough to think it's cool and it's welcome when I want it and know clearly what it is I'm getting. A few years ago I would've been heartbroken. I'm more man now to accept reality and also to accept the reality of musical fun through distortion, but a foundation of clarity such as the O2 gives is necessary to me. Could you imagine what would happen if I spun a track from my DAW with distorted or uncorrectable equipment?
I'm not surprised by your findings. I was playing around with my DAW (Adobe Audition, in this case) a few months back and found that if I introduce very small amounts of delay or overlay delay at different frequencies that I could push the sound outside my headphones. It was fantastic and I think it's the kind of trick I'd like to employ for some recordings.
What I'm telling you is that your tube amp has very likely introduced distortion so that there is a fractional time delay on one channel. It may also be something else, but my experience tells me that time delays are the way to make things 3D. I hope you enjoy it. I'm mature enough to think it's cool and it's welcome when I want it and know clearly what it is I'm getting. A few years ago I would've been heartbroken. I'm more man now to accept reality and also to accept the reality of musical fun through distortion, but a foundation of clarity such as the O2 gives is necessary to me. Could you imagine what would happen if I spun a track from my DAW with distorted or uncorrectable equipment?
And to be more specific C9 has the larger charge.
EDIT: Even more information. I installed all the amps and I now get .68 over C9. -1.24 over C8 and -5.4 total. Tried with batteries and got 1:2 ratio again. Did I fry a MOSFET? Is there a way to check the MOSFETS?
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@ethanolson No doubt! I have been in love with my tubes for many years. I have owned top of the line conrad johnson gear, and lots in between. I agree that there is something "else" going on. I don't care... I just know what sounds good to my ears!
Edit: And the O2 is definitely one of the good sounding ones!
Edit: And the O2 is definitely one of the good sounding ones!
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I didn't realize the K701 is technically gone. That's kind of sad. But it seems it's just been "re-born" as the Q701 with Quincy Jones branding and now also available in neon green!
The Q701 is rated at 200 mW at 62 ohms. That's 3.5 Vrms and I was only suggesting 3.2 Vrms. So if you use your Redbook source, at a "high" 2.1 volts, that's 3.5/2.1 = 1.7X and you're correct the gain resistor would be in the 2.1 - 2.2K range.
The big difference is the question was what gain to use with an iPod as the source. To get the same 3.2V you need 3.2X - 6.4X gain depending on if you're using the LOD or headphone output.
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Something is very likely wrong with your amp if R1 is getting hotter than R2 and U6 hotter than U5. You may have a battery problem--either a bad battery that won't fully charge, or worse, a battery in backwards.
Measure the DC voltage across C2 and C3. They should both be the same and over 17 volts. If not, there's a problem with your meter (DMM), wall transformer, D3, D4, or most likely, U5 or U6. The regulators could have a solder bridge, be in backwards, or be in the wrong locations on the board.
If you do measure over 17 volts for both C2 and C3 but only 7.5 volts at the battery terminals (with no batteries connected), I would also check the regulators as well as D1, D5, R1 and R2.
I'm not sure under what conditions we're talking about? After the amp is shut off, C8 and C9 may measure somewhat differently. But with the amp powered on they should be the same. And if you're doing the "one battery test" they should read as outlined in the testing section.
Sorry for the lack of information.
That was with AC power and only U2 install. I installed all the amps and still had the problem, getting .68 over C9. -1.24 over C8 and -5.4 total. Tried with batteries and got 1:2 ratio again.
Also checked P2 and got voltages just over 1. Same with measuring from the center pin to the outer ones of the jack.
edit: I did the other checks as well. The voltage at C2 and C3 are good (17). I checked the ground to R1 and R2 and they were good as well (almost 12). The D1, D2, D5, and D6 measure about .2 or .190 (while powered on).
D3 and D4 measure in the .560/.570s (powered off) and have continuity (Should they?) when powered on.
That was with AC power and only U2 install. I installed all the amps and still had the problem, getting .68 over C9. -1.24 over C8 and -5.4 total. Tried with batteries and got 1:2 ratio again.
Also checked P2 and got voltages just over 1. Same with measuring from the center pin to the outer ones of the jack.
edit: I did the other checks as well. The voltage at C2 and C3 are good (17). I checked the ground to R1 and R2 and they were good as well (almost 12). The D1, D2, D5, and D6 measure about .2 or .190 (while powered on).
D3 and D4 measure in the .560/.570s (powered off) and have continuity (Should they?) when powered on.
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I guess I need to work on a trouble shooting section for the blog. At least 9 out of 10 builds seem to be working fine on the first try and most of the rest have some obvious problem. But a few are tough to diagnose. Any help or ideas from others would be very welcome.
I can't stress enough to double check the right components are in the right locations oriented the correct way. And to make sure all solder connections look good with no tiny bridges (shorts) anywhere. Nearly every problem so far has been one of these things being wrong.
The basic trouble shooting technique when voltages are wrong is to work backwards "upstream" until you (hopefully) find normal voltages and that usually points to where the problem likely is I'll put together a table of what voltages should be along with some things to check when they're not. I'm not sure when I'll have that done, however.
In your case, if the regulators are not getting hot, there's something wrong in the power supply--i.e. before C8 and C9 and not in any of the audio circuitry. I would remove all the op amps (leave U2) to be safe. If the regulators are getting hot, you could have a problem anywhere.
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@billyk, measure the voltage across both R1 and R2 with AC power and the batteries in place both with the amp on and off. The voltages should be the same. If they're the same, they should be the same temperature if they're both the same value resistors--i.e. 220 ohms (red red brown). If the R1 and R2 voltages don't match, measure across each battery. If they're not the same let the amp charge overnight and re-test the voltages.
So I recently finished my build, and at first attempt everything seemed perfect. While I was building it, I did end up realizing that a few of the resistors I picked up were wrong. All of the 1/8 watt resistors in the BOM, I some how ended up getting 1/20 watt resistors. I didn't realize until later, but but things seemed to work initially. I am planning on switching out those resistors for the corresponding and playing around with the gain settings, but at the moment, I'm thinking my issue is with something else, I'm no expert though, so I'll let someone knowledgeable help me out. This is my first diy project and really the first time I've picked up a soldering iron, so I'm quite proud of myself despite the current predicament.
Anyways, after first firing it up, and the sound was good and everything was working. I then started to notice after about 1.5min the right channel started to get fuzzy, and about a minute later, no sound from the right channel at all. I recheck everything, and all looked to be well. I took some extra care to make sure none other solder points were touching the case. I fired it up again and same exact issue. I tried both gain settings as well. The interesting thing is that if I quickly turn it off then back on, the sound comes back normal and everything sounds great, but until 1.5min later when the issue comes back. I'm not sure what else to try other than ordering up those resistors, but I would assume it's not related since its only the right channel that is having the issue. Anyone have any ideas?
Sent from my Transformer TF101 using Tapatalk
Anyways, after first firing it up, and the sound was good and everything was working. I then started to notice after about 1.5min the right channel started to get fuzzy, and about a minute later, no sound from the right channel at all. I recheck everything, and all looked to be well. I took some extra care to make sure none other solder points were touching the case. I fired it up again and same exact issue. I tried both gain settings as well. The interesting thing is that if I quickly turn it off then back on, the sound comes back normal and everything sounds great, but until 1.5min later when the issue comes back. I'm not sure what else to try other than ordering up those resistors, but I would assume it's not related since its only the right channel that is having the issue. Anyone have any ideas?
Sent from my Transformer TF101 using Tapatalk
matthaios, the 1/20 watt resistors are probably the Mil Spec Vishay "ugprades" and they're great. You don't need to replace them. They're "de-rated" for military use but they're really 1/8 watt resistors.
The term "1/8 watt" resistor is sort of used like "Kleenex" to describe a paper tissue. It generically means resistors about 3.5mm long versus about 6 - 7mm long for "1/4 watt" resistors. The actual power ratings are set by the manufactures and they vary quite a bit. For the mil spec parts, they're very conservative.
Your problem sounds like something getting hot? Have you checked for that?
The term "1/8 watt" resistor is sort of used like "Kleenex" to describe a paper tissue. It generically means resistors about 3.5mm long versus about 6 - 7mm long for "1/4 watt" resistors. The actual power ratings are set by the manufactures and they vary quite a bit. For the mil spec parts, they're very conservative.
Your problem sounds like something getting hot? Have you checked for that?
JDS Labs Experience
I wanted to let everyone know about my recent experience with JDS Labs. I looked for a group buy for O2 boards and front panels on the forums and after a while got frustrated. I decided to order the parts from JDS Labs after the site was suggested to me. I ordered 8 sets of PWBs and front panels. The raw boards were $8.95 each and the front panels $10 each. The shipping for the entire order was $6.25. I was surprised that JDS Labs wasn't trying to make money on shipping as some companies do. I decided to call them and spoke with the contact person John Seaber. I was very impressed with John. I have spoken with him twice now and both times he has been very helpful. After I receive the shipment, I will let inspect the boards and front panels and let everyone know what my findings are.
Roger
I wanted to let everyone know about my recent experience with JDS Labs. I looked for a group buy for O2 boards and front panels on the forums and after a while got frustrated. I decided to order the parts from JDS Labs after the site was suggested to me. I ordered 8 sets of PWBs and front panels. The raw boards were $8.95 each and the front panels $10 each. The shipping for the entire order was $6.25. I was surprised that JDS Labs wasn't trying to make money on shipping as some companies do. I decided to call them and spoke with the contact person John Seaber. I was very impressed with John. I have spoken with him twice now and both times he has been very helpful. After I receive the shipment, I will let inspect the boards and front panels and let everyone know what my findings are.
Roger
I'd have to second that. I've emailed John with questions before and he was very prompt and helpful. I've had 4 orders from him through the past 2 weeks and all of them were shipped very quickly. The last one, I got the shipment notification 5 min after my order!