As always... PHOTOS..... Clear PHOTOS of everything.
A lot of issues can be spotted by fresh sets of eyes.
I was under the impression the amp shouldn't be hooked up (input or output) while biasing the amp? Wouldn't that screw up the bias settings?
The amp should be isolated, just the power supply hooked up, while biasing the amp.
Impressions not required when you've got these cool build guides available for reference - check Step 51:
Amp Camp Amp V1.6 Build Guide - diyAudio Guides
Neel yes, measure with ALL components in place. (The pictures in step 56 of the build guide are to more clearly show the test points, some of which are obscured when the larger components are in place.)
Alan
Try some quick shortcuts to get a handle on the fault.
Applying a short from G to S on Q2 (the upper FET) should see the current fall to almost zero. If it does then you have an issue around the current regulator Q3 although there may also be other problems such as a failed lower FET.
If the current doesn't drop then you need to dig deeper. Q2 will faulty in this scenario but you need to find out why.
Also check the source resistors
Applying a short from G to S on Q2 (the upper FET) should see the current fall to almost zero. If it does then you have an issue around the current regulator Q3 although there may also be other problems such as a failed lower FET.
If the current doesn't drop then you need to dig deeper. Q2 will faulty in this scenario but you need to find out why.
Also check the source resistors
Hi I have a different problem.
The amp connected to an ipod wouldn't even blow the skin off a rice pudding at full chat.
I used a Meanwell 24v 5amp 120w supply, it delivered bang on 24v, the bias was set exactly to 12v.
Speakers used so far: Tannoy 631's (87db), M.Short MS10 (not the MS10i's) (88db).
Very disappointed in performance, I can't even annoy my kids in the next room at these pathetic volumes, I had to turn up the ipod at least to half volume until I heard anything at all.
I think I read here somewhere that ipods only give out .5v (and I think line level is around 2v) so maybe gain too low at source.
I'm building an Objective2 Head amp to double as a pre amp and hoping the gain boost will help here.
Other than that, any ideas folks?
The amp connected to an ipod wouldn't even blow the skin off a rice pudding at full chat.
I used a Meanwell 24v 5amp 120w supply, it delivered bang on 24v, the bias was set exactly to 12v.
Speakers used so far: Tannoy 631's (87db), M.Short MS10 (not the MS10i's) (88db).
Very disappointed in performance, I can't even annoy my kids in the next room at these pathetic volumes, I had to turn up the ipod at least to half volume until I heard anything at all.
I think I read here somewhere that ipods only give out .5v (and I think line level is around 2v) so maybe gain too low at source.
I'm building an Objective2 Head amp to double as a pre amp and hoping the gain boost will help here.
Other than that, any ideas folks?
I've experienced problems with ipads delivering a really low output.when we run in to a mixing desk (in this case a sound craft si compact 32 (?)) we have had to add a ton of gain on the input, like 40db or so. I never got to the bottom of it but I think it could be a similar problem. Your speakers at 87db probably wouldn't go too loud with this amp anyway, but should be enough for a pleasant listening experience. Have you got a different source you can try? If not, I seem to remember that the gain of the circuit can be increased by changing one of the resistor values. Might be worth searching for that.
I'm using a yamaha music cast wxc50 and the combination was plenty to drive a pair of mission 733i (~89db I think) to fairly decent level. Louder than I generally need to hear the music comfortably.
I'm using a yamaha music cast wxc50 and the combination was plenty to drive a pair of mission 733i (~89db I think) to fairly decent level. Louder than I generally need to hear the music comfortably.
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Neel007 - check for resistance between your mosfet pins and the sink. You are clearly drawing way too much current, so something is shorted. Increasing the bias is causing your PSU to go into protect mode and shut down. If you did all of the metal work yourself, there is a chance that a very thin sliver of metal left over from drilling/tapping got trapped under your mosfet. Other than that, you have an inadvertent solder bridge somewhere on your board. Check the back of the board with a strong light and a magnifying glass. Scratch with a fine-tipped screwdriver between ALL solder pads/joints.
semmyroundel: Something is not correct in your wiring. My daughter runs her ACA (original version boards) directly from her iPod into a pair of Mark Audio CHR-70 drivers (85dB sensitivity) in a small bass-reflex cabinet. It gets plenty loud and we often need to tell her to turn it down when the younger one goes to bed (down the hallway and through two closed doors). Same protocol applies for trouble shooting: post well-let and in-focus images so people can have a look at what is going on.
semmyroundel: Something is not correct in your wiring. My daughter runs her ACA (original version boards) directly from her iPod into a pair of Mark Audio CHR-70 drivers (85dB sensitivity) in a small bass-reflex cabinet. It gets plenty loud and we often need to tell her to turn it down when the younger one goes to bed (down the hallway and through two closed doors). Same protocol applies for trouble shooting: post well-let and in-focus images so people can have a look at what is going on.
Thanks for both those replies, I will post photos and of course, I'm only human, so I could've gotten something wrong, but I copied the wiring exactly as on the guide photos, incidentally, all components are from DiyAudio as a kit except for the chassis.
In the meantime, what is anyone thinking might be wrong ?
Gain with the ACA is low. For example, with my 86dB efficient Wharfedale speakers, I had to have my Classe preamp at the 1 o'clock position to get the same kind of volume levels as 9 o'clock with an old Adcom 545 amplifier.
Another option - decrease the feedback, which will in turn increase the gain.
Preamplifier, unless you have a strong source, is a must with the ACA.
I expect there is nothing wrong with the ACA. Many people using their smart phone report exactly the same as you. You can measure its output and convince yourself the ACA is working just fine if you go back to post #5965. The ratio of input to output should be 1 to 3.3 to 3.6.
You will need a pre-amp for best results, something with another 6 or 10dB of gain. Even for 2 volt sources like CD players etc.. Read back and you will see, Alan
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Did you measure ALL of the resistors before stuffing the boards? If your wiring is correct, my next guess is to go after the feedback resistor as others have already pointed out. The value of R12 in the original version is 68k. It seems that more recent versions have lowered R12 to 39k. Maybe raising R12 to somewhere between 68k and 100k will restore some of the volume you are looking for.
Many thanks Alan, and others who replied.
I just plugged in my Marantz 6005 cd player with phono leads.
I had no way of attenuating, but what a difference!
Now at that level it's way too loud, I'm hoping now that the objective2 headphone amp doesn't add too much gain (I understand that the gain switch switches between 2.5x and 6x), quite why 2.5x ends up as 10x gain, I don't understand.
As I'll be doubling this as a headphone amp, should I leave those values alone?
Thanks to all again.
Eric, yes I did, and shortly after soldering too, this is the latest batch so would had 39k.
I'm diligent about these things so was a bit puzzled, anyway, as you'll see from my other reply, I have it working beautifully now, just sort out the preamp and I'm done.
Hello semiroundel. It is obvious to me that there are holes in your understanding of the broad spectrum of issues involving music recording and reproduction. There is nothing wrong about this, nobody is born with this knowledge, they acquire it. So, knowing that I am likely to bore most people in this forum to death, I think I will give you a quick overview. Music used to be recorded, and reproduced in a totally analog fashion. This was the time of vinyl records (and earlier types of records) amps and pre amps. Then came the CDs which recorded in digital fashion. The output of a CD is digital and needs a DAC (digital to analog converter) to become analog again. Please understand that the main amplifiers, the ones that will drive the speakers, and make pure music are (as the speakers) purely analog. So you have the DAC producing an analog output from the CD digital input. This needs to be beefed up (pre amplified) in an analog way before it gets to the amplifier. This is particularly true for amps that have low outpuut like ACA 1.6.
To complicate matters CDs as a recording medium for music is becoming outdated, the new and widespread mode of recording music is MP-3. This is again a digital form of recording that needs to be processed into analog, etc... Your IPod has this kind of equipment which is meant to drive headphones, which means the analog output level is rather small.
However your Marantz 6005 already has IPod input in the form of a USB so you can use it to play MP-3s. So, look at it this way: 1. the Marantz 6005 provides a way to accept CD and MP-3 inputs. 2. The Marantz has a perfectly functional DAC to tanslate the input digital stream to analog. 3. The Marantz has preamp analog functionality that gives you a beefy input to your ACA.
So, what you need now is volume control. You do not need another DAC or another preamp. Assuming you are using the RCA (right and left plugs in the back of the Marantz) to feed your ACA, all you really need is a double pot attenuator for volume control. I got mine in eBay, not expensive at all. Now, if you need to get fancy the sky is the limit. However I suggest you use the Marantz 6005 as your source and the ACA as your amp, with a double pot (pre manufactured of course) for volume control and you are set. Voila c'est fini.
I cannot use French accents in this computer.
All the best
I wish you all the best in your musical journey and remember that if you want to improve the musical quality of your rig, the sky (and the price) is the limit. From my point of view, start low and enjoy the music.
To complicate matters CDs as a recording medium for music is becoming outdated, the new and widespread mode of recording music is MP-3. This is again a digital form of recording that needs to be processed into analog, etc... Your IPod has this kind of equipment which is meant to drive headphones, which means the analog output level is rather small.
However your Marantz 6005 already has IPod input in the form of a USB so you can use it to play MP-3s. So, look at it this way: 1. the Marantz 6005 provides a way to accept CD and MP-3 inputs. 2. The Marantz has a perfectly functional DAC to tanslate the input digital stream to analog. 3. The Marantz has preamp analog functionality that gives you a beefy input to your ACA.
So, what you need now is volume control. You do not need another DAC or another preamp. Assuming you are using the RCA (right and left plugs in the back of the Marantz) to feed your ACA, all you really need is a double pot attenuator for volume control. I got mine in eBay, not expensive at all. Now, if you need to get fancy the sky is the limit. However I suggest you use the Marantz 6005 as your source and the ACA as your amp, with a double pot (pre manufactured of course) for volume control and you are set. Voila c'est fini.
I cannot use French accents in this computer.
All the best
I wish you all the best in your musical journey and remember that if you want to improve the musical quality of your rig, the sky (and the price) is the limit. From my point of view, start low and enjoy the music.
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Hi Oc11, thanks for that comprehensive run down of recording and reproduction of music, which, I should say, I have a perfectly good understanding of. An assumption about someone can be a dangerous thing, especially if you hardly know them. Luckily I'm quite relaxed about such things.
At 55, I've had many years of education in recording and reproduction of music, having worked for Sony in the eighties and having done some observation of a music producer at work at Abbey Road Studios.
My current setup at home comprises of a Quad power and pre amp coupled with Spendor speakers, a combination that faithfully reproduces the music (crucially for me) as it was recorded, with no colouration. I SPECIFICALLY chose that setup in order that I could hear the recordings WARTS and all.
In fact this was put to the test when I purchased a 180gramme vinyl copy of an early Warren Zevon album, only to find it sounded worse than the cd copy- the cd had been remastered, and the vinyl was recorded straight from the masters (as close as, anyway) thus exposing the humble heritage of the studio or recording equipment or engineer, whatever.
I still like it because that's the way it was recorded.
My Rega Planar 3 coupled with a Sumiko Blue point special MC is about as good as it gets without paying silly money.
No, my holes in my understanding are concerning electronics, I find it difficult to follow wiring diagrams due to a defficiency in my learning ability, but I can build things well.
I've built the Brian Gt LM3886 chipamp to great success, making it into the duoble mono variant with an alps blue pot and an alps selector switch, and also the Tripath TA3020 T class amp from 41hz, again, to great success with Alps pot and selector switch.
I simply had read on this very forum that the ACA was being used with an Ipod as source (I was sceptical knowing that the output was low) as I even have a small opamp headphone amplifier to use when I plug in my Sennheiser SP11, however when using my Etymotic in-ear it's not necessary of course.
As for MP3 they could be stuck where the sun don't shine, even Atrac's algorithms aren't all that.
No I'm a vinyl and cd man, and may investigate flac AIFF, wav and other high-bitrate methods of listening, but not in a hurry to do so.