t. said:
IIRC, there are quite a few 0.1uF power supply decoupling caps, close to supply pins for the chip. My Amp3 is very well behaved, with just about zero noise of any sort. If I press my ears to the tweeter, I hear tiny broadband hiss, but it's really tiny. On fairly high sensitivity Lowthers, the owner remarked how quiet the Amp3 was compared to his megabuck tube pre/power.
On the Norah Jones "Come Away" cd, I do hear a faint whistle on track 2 (only), and I hear it on all systems thus far, with various source / amp combinations. There have been reports of pirate versions of the cd that sound bad, but people who have seen my case lable / cd feel I have the 'real thing'. It is a fairly soft sound...
Nuuk: have you implemented the C1 fix, so that the n/c terminal of the cap goes to ground? As per my usual practice, I have some additional filtering (X2 cap) at the IEC power inlet and schottkys for rectification. Are you using smps power? Could it be that the music segment just induces someIM products between the smps frequency and Tripath's modulation frequency? Yes, I realise this is very non-scientific, but that would be my be suspicion.
I don't know if this helps or not, but on Jans site someone mentioned that they had whistling on a AMP1 or 2, I forget which, and the problem eventually was solved with shielded cables inside and out. Improper inductor winding was also suspect i.e. overlapping at the beginning and or end of the windings.
Hope you get it figured out. That must be annoying.
Hope you get it figured out. That must be annoying.
Update
I tried a different DAC but the whistling was still there.
So I tried another amp - the Autostriure 2020 and the whistling was still there.
So I tried the DiYParadise Charlize (2020) and same again.
Due to the present set up, it's not easy to put a Gainclone back in but I have listened to this track hundreds of times on a GC and never noticed the whistling!
So, it's not a problem confined to the AMP-3 but looks like somethnig that may affect this type of amplifier. If that's the case, we should have a few more people noticing it!
I tried a different DAC but the whistling was still there.
So I tried another amp - the Autostriure 2020 and the whistling was still there.
So I tried the DiYParadise Charlize (2020) and same again.
Due to the present set up, it's not easy to put a Gainclone back in but I have listened to this track hundreds of times on a GC and never noticed the whistling!
So, it's not a problem confined to the AMP-3 but looks like somethnig that may affect this type of amplifier. If that's the case, we should have a few more people noticing it!
Hi,
Just to say i too have noticed a high ptched whistling on my Amp3 on a few occasions as well. The other day my girlfriend stuck in an enya cd and it happened very noticeably, i at first thought it to be something duff with the cd player. I had removed the muted transisotrs on my arcam alpha 5 (and also done a shed load other stuff to it). However i am now sure it is the amp causing the issue since i have never heard any such sound before from chipamps. It is odd sound but happens pretty rarely just a certain sound in a certain passages of music, odd stuff for sure.
It in no way detract from the overal satiscation i have had from my Amp3, which i have to say in my favourite amp soundwise. Howver it would be nice if there was some way to tame this issue. Very interesting stuff from you Nuuk saying the Autostriure and Charlize have the same issue. Seem like a total tripath issue then rather than a specific layout or chip. Like i say for the performance you are getting it is hard to complain but it would be nice to know what causes this and if it could be removed.
Phil
Just to say i too have noticed a high ptched whistling on my Amp3 on a few occasions as well. The other day my girlfriend stuck in an enya cd and it happened very noticeably, i at first thought it to be something duff with the cd player. I had removed the muted transisotrs on my arcam alpha 5 (and also done a shed load other stuff to it). However i am now sure it is the amp causing the issue since i have never heard any such sound before from chipamps. It is odd sound but happens pretty rarely just a certain sound in a certain passages of music, odd stuff for sure.
It in no way detract from the overal satiscation i have had from my Amp3, which i have to say in my favourite amp soundwise. Howver it would be nice if there was some way to tame this issue. Very interesting stuff from you Nuuk saying the Autostriure and Charlize have the same issue. Seem like a total tripath issue then rather than a specific layout or chip. Like i say for the performance you are getting it is hard to complain but it would be nice to know what causes this and if it could be removed.
Phil
HF noise
You might be hearing the cd sampling rate beating with the program material causing intermodulation artifacts to be generated. This can and does happen but usually is filtered out to inaudible levels. The difference could be these class D amps don't hide it or filter it out. IMHO it also is a real possibility that the sampling frequency residual could be beating with the self oscillation frequency. Since the frequency is somewhat dependant on the program I could see this as a possibility. The test would be to implement a brick wall 20-24KHz input filter and see what happens. It would be hard to believe it had a cause outside the cd player its self with all the different configurations that have exhibited the problem. This would include defective cds as a possibility as well.
I have not heard this myself, with my amp3 so can’t go any further.
Roger
You might be hearing the cd sampling rate beating with the program material causing intermodulation artifacts to be generated. This can and does happen but usually is filtered out to inaudible levels. The difference could be these class D amps don't hide it or filter it out. IMHO it also is a real possibility that the sampling frequency residual could be beating with the self oscillation frequency. Since the frequency is somewhat dependant on the program I could see this as a possibility. The test would be to implement a brick wall 20-24KHz input filter and see what happens. It would be hard to believe it had a cause outside the cd player its self with all the different configurations that have exhibited the problem. This would include defective cds as a possibility as well.
I have not heard this myself, with my amp3 so can’t go any further.
Roger
Hi there!
I'm a complete newbie to this but started to get hooked up ever since I saw the reviews about the SI T-Amp. I'm a lot into DIY so I want to make a good sounding amp at little cost. Since I never did like loud music I'm going for the Amp-3. Since this thread is about this amp I though I place my (extremely) basic questions, which are
....
- I'll be using a 12V, 5A laptop power suply like this one taht I just won on ebay realy cheap (1.04£
)
http://www.digidave.co.uk/product_i...d=143&osCsid=06308c83b1dce4a08b72c73b2e0b4b65
is this a regulated power suply or should I add something else to it before the AMP3 board?
- I'll probably be using low sensitivity (86-87 dB) speakers that can be bi-wired. If ater on I decide that one AMP3 is too little for these can I add a second one:
- using the same power suply or adding a new one
- using the same potentiometer for volume control (both amps working in parallel, one for each speaker
more painful questions on he way as soon as I order the kit... but the case is being built already! (big enough to put two amps and two power suplies + whatever needed as it will be 10cm high x 28cm long x 28 cm wide)
I've been wondering arround the net looking for info and for the best way to do this but if my questions are too basic or answered somewhere else, can you please point me to the right direction?
Thank you in advance for your comments! Paulo P.
I'm a complete newbie to this but started to get hooked up ever since I saw the reviews about the SI T-Amp. I'm a lot into DIY so I want to make a good sounding amp at little cost. Since I never did like loud music I'm going for the Amp-3. Since this thread is about this amp I though I place my (extremely) basic questions, which are
....- I'll be using a 12V, 5A laptop power suply like this one taht I just won on ebay realy cheap (1.04£
)http://www.digidave.co.uk/product_i...d=143&osCsid=06308c83b1dce4a08b72c73b2e0b4b65
is this a regulated power suply or should I add something else to it before the AMP3 board?
- I'll probably be using low sensitivity (86-87 dB) speakers that can be bi-wired. If ater on I decide that one AMP3 is too little for these can I add a second one:
- using the same power suply or adding a new one
- using the same potentiometer for volume control (both amps working in parallel, one for each speaker
more painful questions on he way as soon as I order the kit... but the case is being built already! (big enough to put two amps and two power suplies + whatever needed as it will be 10cm high x 28cm long x 28 cm wide)
I've been wondering arround the net looking for info and for the best way to do this but if my questions are too basic or answered somewhere else, can you please point me to the right direction?
Thank you in advance for your comments! Paulo P.
Paulo, that PSU should be regulated but to be safe, check with the supplier! You don't want the voltage drifiting up and cooking the chip!
Yes, you can add another AMP-3 later on and bi-amp using a single volume control or pre-amp. It will probably produce very good results!
The AMP-3 isn't that low-powered compared to the other class-T amps but have you considered the other options?
Yes, you can add another AMP-3 later on and bi-amp using a single volume control or pre-amp. It will probably produce very good results!
The AMP-3 isn't that low-powered compared to the other class-T amps but have you considered the other options?
Thanks for the reply Nuuk!
You mean either Amp1 or Amp2? Yes, I've considered them but I want to keep it simple to assemble and easy to find the parts. The 30V and 5V power needed would be a PITA for me... and building one from scratch even more... so this is good compromise for me. Anyways, the idea for a second unit is not really for added power as I don't listen to music very loud, only to try to squeeze some more quality ou of these little things. Has anyone ever tried to do this with these amps? How did it sound?
If I do include another AMP3 in the box I can then use the same volume pot (a 50K one, right?) for both, is that it? I just solder the outputs from the pot to the boards in parallel with nothing else required? How about power? I probably should add a second PSU to have both running without problems... Anyway, as I said, I'm making a big housing (out of painted alluminum sheets used for false ceilings!) so I can put in more stuf later, if needed.
Thanks and sorry for so many more questions... But I want to try to get this right the first time.
Paulo.
You mean either Amp1 or Amp2? Yes, I've considered them but I want to keep it simple to assemble and easy to find the parts. The 30V and 5V power needed would be a PITA for me... and building one from scratch even more... so this is good compromise for me. Anyways, the idea for a second unit is not really for added power as I don't listen to music very loud, only to try to squeeze some more quality ou of these little things. Has anyone ever tried to do this with these amps? How did it sound?
If I do include another AMP3 in the box I can then use the same volume pot (a 50K one, right?) for both, is that it? I just solder the outputs from the pot to the boards in parallel with nothing else required? How about power? I probably should add a second PSU to have both running without problems... Anyway, as I said, I'm making a big housing (out of painted alluminum sheets used for false ceilings!) so I can put in more stuf later, if needed.
Thanks and sorry for so many more questions...
But I want to try to get this right the first time.Paulo.
No, I was thnking of the Autostriure 2020 and the DiyParadise 2020! They both run of a 12 volt PSU.
Yes, if you have two power amps, use two PSU's. They are cheap enough for this sort of amp!
To connect two amps, you do as you say and connect them in parallel from the volume control. 10K-50K is fine for the volume control.
Hi Nuuk,
It seems that you have all the different Class-D kits, 41Hz amp3, diyparadise Charlize, 2020 Autoconstruire ... when are you going to tell us how the compare?
I fried my second amp3 the other day trying to find a cold joint with PENCIL and made a short between the Tripath pins, seen a little spark, and made a loud POP at speakers.
Cheers.
It seems that you have all the different Class-D kits, 41Hz amp3, diyparadise Charlize, 2020 Autoconstruire ... when are you going to tell us how the compare?
I fried my second amp3 the other day trying to find a cold joint with PENCIL and made a short between the Tripath pins, seen a little spark, and made a loud POP at speakers.
Cheers.
A question of power and biamping
“ I'll be using a 12V, 5A laptop power suply like this one taht I just won on ebay realy cheap (1.04£ )
http://www.digidave.co.uk/product_i...b72c73b2e0b4b65
is this a regulated power suply or should I add something else to it before the AMP3 board?
- I'll probably be using low sensitivity (86-87 dB) speakers that can be bi-wired. If ater on I decide that one AMP3 is too little for these can I add a second one:
- using the same power suply or adding a new one
- using the same potentiometer for volume control (both amps working in parallel, one for each speaker
more painful questions on he way as soon as I order the kit... but the case is being built already! (big enough to put two amps and two power suplies + whatever needed as it will be 10cm high x 28cm long x 28 cm wide)
I've been wondering arround the net looking for info and for the best way to do this but if my questions are too basic or answered somewhere else, can you please point me to the right direction?
Thank you in advance for your comments! Paulo P.”
Paulo,
The power supply you have is powerful enough to run 4 channels/2 separate amps with no problem. It is regulated and will probably have an adjustment inside so you can adjust it up to 13.5v. This way you will get more power but not risk damage to the amps. The screws holding the power supply case together will be under a label or under stick on feet.
Inside your amp case install a buffer cap across the 12v (13.5v) power. This cap should be 22-33,000 uf @ 16V. Run 3 pairs of wires from this cap; one pair to each amp and one to the power input jack. Tightly twist these wires together as +/- pairs.
Connect one twisted shielded cable from each output of the volume control to an input on each amp. On the amp jumper the 2 channels inputs together with a short jumper wire. Connect the ground to only one common point on the amp and connect the cable shield at one end only. Connect the volume control to the RCA input jack with another piece of twisted shielded cable and once again only connect the shield at one end. The RCA connectors ground must be isolated from the case but can and should be connected to it with a small film cap. (.1uf @ 100v)
If you want to ground the case connect another wire from the buffer cap – lead to the case. Also I would recommend a 10k value for the volume control and the higher the quality the better the sound will be.
Later on you can build an active crossover and get rid on your passive ones. This can be done right in the same amp case and will astound you with the improvement!
Roger
“ I'll be using a 12V, 5A laptop power suply like this one taht I just won on ebay realy cheap (1.04£ )
http://www.digidave.co.uk/product_i...b72c73b2e0b4b65
is this a regulated power suply or should I add something else to it before the AMP3 board?
- I'll probably be using low sensitivity (86-87 dB) speakers that can be bi-wired. If ater on I decide that one AMP3 is too little for these can I add a second one:
- using the same power suply or adding a new one
- using the same potentiometer for volume control (both amps working in parallel, one for each speaker
more painful questions on he way as soon as I order the kit... but the case is being built already! (big enough to put two amps and two power suplies + whatever needed as it will be 10cm high x 28cm long x 28 cm wide)
I've been wondering arround the net looking for info and for the best way to do this but if my questions are too basic or answered somewhere else, can you please point me to the right direction?
Thank you in advance for your comments! Paulo P.”
Paulo,
The power supply you have is powerful enough to run 4 channels/2 separate amps with no problem. It is regulated and will probably have an adjustment inside so you can adjust it up to 13.5v. This way you will get more power but not risk damage to the amps. The screws holding the power supply case together will be under a label or under stick on feet.
Inside your amp case install a buffer cap across the 12v (13.5v) power. This cap should be 22-33,000 uf @ 16V. Run 3 pairs of wires from this cap; one pair to each amp and one to the power input jack. Tightly twist these wires together as +/- pairs.
Connect one twisted shielded cable from each output of the volume control to an input on each amp. On the amp jumper the 2 channels inputs together with a short jumper wire. Connect the ground to only one common point on the amp and connect the cable shield at one end only. Connect the volume control to the RCA input jack with another piece of twisted shielded cable and once again only connect the shield at one end. The RCA connectors ground must be isolated from the case but can and should be connected to it with a small film cap. (.1uf @ 100v)
If you want to ground the case connect another wire from the buffer cap – lead to the case. Also I would recommend a 10k value for the volume control and the higher the quality the better the sound will be.
Later on you can build an active crossover and get rid on your passive ones. This can be done right in the same amp case and will astound you with the improvement!
Roger
The class-T amps are innocent!
WOW, I just hooked up a Gainclone and listened to the 'whistling' track and it'sstill there. So it's on the CD!
I don't know why I haven't noticed it before! It's quite clear although perhaps not as prominent with the GC as with the class-T amps..
Can you other 'whistle spotters' try another amp and see if the whistle is still there?
And my apologies to the class-T amps, they are not the source of the whistling (at least in my case).
WOW, I just hooked up a Gainclone and listened to the 'whistling' track and it'sstill there. So it's on the CD!
I don't know why I haven't noticed it before! It's quite clear although perhaps not as prominent with the GC as with the class-T amps..
Can you other 'whistle spotters' try another amp and see if the whistle is still there?
And my apologies to the class-T amps, they are not the source of the whistling (at least in my case).
A question of power
Nuuk,
The case will be externally powered so the power input jack is DC, glad to see you are paying attention! Also glad the whistler is the CD. Like I had stated way back, this new technology will force the music companies to clean up their acts, well I hope anyway.
Roger
Roger
Nuuk said:
The review is for an article on TNT!
Roger, don't you mean the power output jack?
Nuuk,
The case will be externally powered so the power input jack is DC, glad to see you are paying attention! Also glad the whistler is the CD. Like I had stated way back, this new technology will force the music companies to clean up their acts, well I hope anyway.
Roger
Roger
where to find parts...?
Sorry to come and nag again but I'm starting to suspect I'll be having a hard time finding the parts needed to complete my (soon to arrive!) AMP3 kit. Can anyone recommend an online store that sells to europe (france) where I can find nice input and output terminals, a good 50K stereo pot with a large metal knob and an AC power input with on-off switch and fuse? I'm going today to the large "bricolage" stores but I seriously doubt they will have any of these...
Thanks,
Paulo
Sorry to come and nag again but I'm starting to suspect I'll be having a hard time finding the parts needed to complete my (soon to arrive!) AMP3 kit. Can anyone recommend an online store that sells to europe (france) where I can find nice input and output terminals, a good 50K stereo pot with a large metal knob and an AC power input with on-off switch and fuse? I'm going today to the large "bricolage" stores but I seriously doubt they will have any of these...
Thanks,
Paulo
check out www.partsexpress.com they ship internationally but require a minimum order of $50.
they have a decent selection of RCA jacks and binding posts as well as a some IEC power jacks, switches, and pots. i'd look for a pot elsewhere though.
www.digikey.com also has the parts you're looking for and has great service. i get most of the parts i need from them because they get your order together and ship it out fast and have a slightly easier to navigate site than www.mouser.com
they have a decent selection of RCA jacks and binding posts as well as a some IEC power jacks, switches, and pots. i'd look for a pot elsewhere though.
www.digikey.com also has the parts you're looking for and has great service. i get most of the parts i need from them because they get your order together and ship it out fast and have a slightly easier to navigate site than www.mouser.com
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