| Nuuk |
When using the 41Hz AMP-3 I get a strange whistling noise (like the sound of a kettle boiling) on at least one track of a CD. The CD in question is 'Natural Light' by Eric Bibb and the whistling is most obvious on track 1.
What is this and the whistling down to the amp, the CD, or both? I didn't notice it with the other class-T amps that I ahve here. :xeye: |
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| t. |
Hi NUUK
I sometimes get a high pitched whistle with my Amp3
It seems to be when I use either of my NOS dacs most noticeable if theres no cd in the transport or when I'm loading a disc, its only faint but there is a high pitched noise, I've also noticed a few strange whistling noises on HDCD recorded discs:confused:
Leo |
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| kanaddict |
| quote: | Originally posted by Nuuk
When using the 41Hz AMP-3 I get a strange whistling noise (like the sound of a kettle boiling) on at least one track of a CD. The CD in question is 'Natural Light' by Eric Bibb and the whistling is most obvious on track 1.
What is this and the whistling down to the amp, the CD, or both? I didn't notice it with the other class-T amps that I ahve here. :xeye: |
Hi,
I'm not sure if an experience I previously had could be signifiant here, but just in case. A guy at work have a Maranz reveiver and he had some problem with a particulra CD of Nora Jone. At some specific place of the songs, the amp was delivering a suspect noise. I can't tell you exactly how it sounded as I never visited this person. Anyway, he ask me to listen to the CD to see if the CD was bad and I had no such problem. So, he went to his Hi-Fi store and they finally found that the amp was not able to take the load during the "peak" of this CD. I suppose that the CD was recorded to hight as the music was very soft.
Maybe you have some similar problem with the amp3. You have to listen to many CD and see if it always happen and when it happen.
Regards, |
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| Nuuk |
| quote: | | I sometimes get a high pitched whistle with my Amp3 |
Hi Leo, I was just going to email you! OK, so I am not alone here!
Now we need to know if anybody else has experienced 'the whistle'! :att'n: |
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| t. |
| quote: | Originally posted by Nuuk
Hi Leo, I was just going to email you! OK, so I am not alone here!
Now we need to know if anybody else has experienced 'the whistle'! :att'n: |
Well I've mailed you anyway:D
The sound of the actual music seems fine and the whistle seems its nothing to do with the actual recording, its like that feeling you get when a tv is on if you know what I mean
Strange:confused: |
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| dnsey |
Years ago, when I was contemplating buying my first CD player, almost all the players I heard demonstrated produced a sound similar to a TV line whistle.
None of the dealers I asked about it claimed to be able to hear it, but it was quite audible to me, and made the music almost unlistenable, and put me off CDs for some time. Eventually I decided I'd have to put up with it in order to listen to any newly released music.
These days I don't hear it any more, whether from a good or a bad player, so either I've become 'immune' to it or (more likely) my old ears don't go that high any more. |
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| Nuuk |
But in my case, it is not continuous! It sounds exactly like my whistling kettle when it boils and I am upstairs with the hi-fi on.
And like I said only noticeable on two tracks of one CD (so far). ;) |
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| classd4sure |
I'm betting it also sounds like a cheap AM radio does when you're tuning stations on it.
http://dictionary.reference.com/search?q=heterodyne
Those difference signals, are your whistle.
Distance and shielding between modules is a good help. Are your modules right next to each other? I don't even know if they're both built on the same PCB so forgive the ignorance.
Is there any kind of low pass on the inputs already?
You could also take measures to attempt to lower the modules EMI, I assume there's some sort of heatsink on it, is it bypassed to ground?
Regards |
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| t. |
| quote: | Originally posted by dnsey
Years ago, when I was contemplating buying my first CD player, almost all the players I heard demonstrated produced a sound similar to a TV line whistle.
None of the dealers I asked about it claimed to be able to hear it, but it was quite audible to me, and made the music almost unlistenable, and put me off CDs for some time. Eventually I decided I'd have to put up with it in order to listen to any newly released music.
These days I don't hear it any more, whether from a good or a bad player, so either I've become 'immune' to it or (more likely) my old ears don't go that high any more. |
Well I've always had very good hearing:)
Mine is doing similar to NUUK though in that its only noticeable on a few cd's at certain parts of a track and normally if there is no cd in the transport |
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| t. |
| quote: | Originally posted by classd4sure
I'm betting it also sounds like a cheap AM radio does when you're tuning stations on it.
http://dictionary.reference.com/search?q=heterodyne
Those difference signals, are your whistle.
Distance and shielding between modules is a good help. Are your modules right next to each other? I don't even know if they're both built on the same PCB so forgive the ignorance.
Is there any kind of low pass on the inputs already?
You could also take measures to attempt to lower the modules EMI, I assume there's some sort of heatsink on it, is it bypassed to ground?
Regards |
Thank you for the link:)
We both use an amp based on the TA2021 so its stereo on a single chip, my psu is in a seperate case.
There is a 100pf cap on the input and ground which I presume is used for the filtering.
It seems strange that its only mainly noticeable on some cd tracks |
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| Nuuk |
| quote: | | I'm betting it also sounds like a cheap AM radio does when you're tuning stations on it. |
Not really. It's a steady single frequency.
I just left the CDP empty, ie without a CD, but I didn't get it as Leo reports!
And the last CD played OK without any whistling so, to date, it is just two tracks on one CD out of about a dozen CD's played. :att'n: |
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| classd4sure |
Hi,
Wow, just had a look at what you're dealing with.
I don't think there's anything you can do aside from live with it or get rid of it.
I can't help but wonder how it would work if one of the channels was routed to the other side of the board with a ground plane in between...
I don't believe tripath's CLASS D (snicker) amps are clocked, they're self oscillating from what I know. That means there's bound to be some level of frequency modulation. With two stereo channels side by side like that.... you will get a heterodyne effect as they'll have a different frequency modulation at any given time while working with different signals. I'm sure they correct for frequency modulation, but when is anything ever perfect? So this makes "only certain parts of certains songs/certain CD's" pretty believable to me at least.
You see why it's only a 25W chip.
All I can think of, but it seems overlycomplex for what it's worth, you'd have to force both modulators to switch at the same time by mixing both inputs with the same clock signal.
PS: Maybe higher quality bypass caps would make a difference? If you can find such a thing. |
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| Nuuk |
Well AFAIK, there are quite a few of these amps in use around the world so it would be strange indeed if Leo and I are the only ones experiencing the whistle! I would still like to herar if anybody else with an AMP-3 (or other class-T amp) has heard it.
Fortunately, I don't have to live with it! ;) |
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| classd4sure |
That's true but .... even then to most people it will be a giant leap forward from what they're used to listening to right?
There's might be made with better PCB designs too. |
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| t. |
I must admit these amps do sound very good for such a compact unit.
The sound is different to my other amps, if its better than my tube amp is hard to say but it is good for sure:)
I think the noise I get when no cd's are in the transport is something to do with the CS8412's in both my dacs or possibly my transport:confused:
I've never noticed it on my other amps though.
NUUK, just out of interest is your Eric Bibb cd HDCD, the ones where I noticed the whistle on some tracks have HDCD stamped on the cover, strange really because both my dacs are not HDCD compatible so its probably nothing to do with it |
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| BWRX |
| Nuuk, do you get the whistling sound at all volume levels or only certain volume levels? and do you still hear the sound if only one channel is driven? from what you've said so far it seems like it has to be the program material on the couple of tracks that you mentioned that is causing the amp to produce an undesirable output. |
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| Nuuk |
| quote: | | NUUK, just out of interest is your Eric Bibb cd HDCD, |
No it's not Leo.
| quote: | | Nuuk, do you get the whistling sound at all volume levels or only certain volume levels? |
At all volume levels but the level of whistle seems to be constant, ie independent of the volume control setting.
| quote: | | and do you still hear the sound if only one channel is driven? |
Well I removed one lead from the DAC and left only the left channel connected (that's the side I notice the whistling most) but I got nothing at all. It seems the DAC only works with both leads connected!
I'll play around tomorrow some more when I am not so tired. I'll also try the other class-T amps with that particular track (Too much stuff).
I should add in fairness that the AMP-3 sounds very good! :) |
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| classd4sure |
Hi guys,
I think it might be worth experimenting with bypass caps, if you find ones with lower ESR and better all around, mounted right over the pins if you have to, it might lower EMI just enough to keep the heterodyning down.
I think with only one channel going it will still whistle, unless you can actually disable/mute just the one channel.. doesn't look like it has that ability though. The other channel will still be oscillating, only at a more less constant frequency since it's not modulating anything.
I'd let the guys at 41hz know about it... maybe they'll rework the PCB or have some other tips for you to try?
Best of luck with it,
Chris |
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| jkeny |
Hi guys,
I know what I've experienced with SI t-amp is not the same but it may have some bearing - when I substituted input section of t-amp (consisting of res & cap to ground & inductor & cap in series) with just 2.2uF cap in series, I noticed the mid range lost some life & sparkle. I tried on 2 different t-amps with the same result. When 2.2uF cap just substitued t-amps 0.3uF cap with all other input components in circuit life & sparkle restored.
I surmissed this might have to do with high freq signals on input section coming from t-amp??
Could this have any relevance?
John |
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| t. |
| quote: | Originally posted by classd4sure
Hi guys,
I think it might be worth experimenting with bypass caps, if you find ones with lower ESR and better all around, mounted right over the pins if you have to, it might lower EMI just enough to keep the heterodyning down.
I think with only one channel going it will still whistle, unless you can actually disable/mute just the one channel.. doesn't look like it has that ability though. The other channel will still be oscillating, only at a more less constant frequency since it's not modulating anything.
I'd let the guys at 41hz know about it... maybe they'll rework the PCB or have some other tips for you to try?
Best of luck with it,
Chris |
Hi Chris,
I use 680uf Blackgate NX type cap on each of the voltage decoupling which are a couple of mm from the chips pins so there is a pair of these on the pcb.
The pcb of the Amp3 is tiny but I can't see any bypass caps on the main supply lines for the chip |
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| mb |
| quote: | Originally posted by t.
Hi Chris,
I use 680uf Blackgate NX type cap on each of the voltage decoupling which are a couple of mm from the chips pins so there is a pair of these on the pcb.
The pcb of the Amp3 is tiny but I can't see any bypass caps on the main supply lines for the chip |
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. |
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| Bearman |
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. |
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| Nuuk |
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! :att'n: |
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| filholder |
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 |
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| sx881663 |
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 |
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| pcspinheiro |
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 :blush: ....
- I'll be using a 12V, 5A laptop power suply like this one taht I just won on ebay realy cheap (1.04£ :D )
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. |
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| Nuuk |
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! :att'n:
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? ;) |
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| pcspinheiro |
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... :blush: But I want to try to get this right the first time.
Paulo. |
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| Nuuk |
| quote: | | You mean either Amp1 or Amp2? |
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. ;) |
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| MrDodo |
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. |
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| sx881663 |
“ 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 |
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| Yves Smolders |
| quote: | 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...
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I've got the SACD and just checked this track, except for very distant hiss there's nothing to be heard. Checked this on a Pioneer 868 source with & double UcD400 - so if it is something class-d related, I can't hear it on the SACD.
Yves |
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| Nuuk |
| quote: | | when are you going to tell us how the compare? |
The review is for an article on TNT! ;)
| quote: | | Run 3 pairs of wires from this cap; one pair to each amp and one to the power input jack. |
Roger, don't you mean the power output jack? :att'n: |
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| Nuuk |
WOW, I just hooked up a Gainclone and listened to the 'whistling' track and it'sstill there. So it's on the CD! :eek:
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? :att'n:
And my apologies to the class-T amps, they are not the source of the whistling (at least in my case). :) |
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| sx881663 |
| quote: | Originally posted by Nuuk
The review is for an article on TNT! ;)
Roger, don't you mean the power output jack? :att'n: |
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 |
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| Nuuk |
| quote: | | The case will be externally powered so the power input jack is DC, glad to see you are paying attention! |
Oops Roger! I wasn't paying attention closely enough (too many amps here to listen to)! :dead: |
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| pcspinheiro |
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 |
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| pcspinheiro |
| As I suspected... can't find the parts I need and no one was able to recommend a place to go to... can you guys help? Wish there was something like radio shack or whatever arround here... |
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| BWRX |
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 |
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| Nuuk |
Nearer home is CPC in England with quite a good range of connectors.
Forget the pot and do the amp justice with a stepped attenuator! ;)
And big knobs are a bespoke item so don't expect to find one off the shelf. You will need to find a friendly local person with a lathe! :att'n: |
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| sx881663 |
| quote: | Originally posted by Nuuk
Nearer home is CPC in England with quite a good range of connectors.
Forget the pot and do the amp justice with a stepped attenuator! ;)
And big knobs are a bespoke item so don't expect to find one off the shelf. You will need to find a friendly local person with a lathe! :att'n: |
Nuuk,
Right on the money! Stepped attenuator is the way to go.
The knob issue is why I bought a small lathe. Even designed and built a radiusing attachment for it. Love the feel of heavy brass knobs with smooth edges. Now if I can figure out some way to get the plating done without it’s costing a fortune.
Roger |
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| MrDodo |
Hello,
Do check at http://www.hificollective.co.uk/com...ntiometers.html for pots. They've got good pots and better still a ladder type Stepped Attenuator with Dale Vishay resistors, hush it's a secret...
That was exactly what I was looking for ages and I ordered one from them...its on its way.
Its the best you can get except if you want to go the Transformer Volume Control way... the Holy Grail
But this cost leg and arm. Does anyone know non-expensive TVC source (I won't say cheap with all that implies) please share but I suspect there ain't any. But I don't despair.
They also have Elma switches and Audio Note knobs that look gorgeous. I'll order them soon to make a passive pre.
Cheers. |
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| sx881663 |
Just a note: I have only checked out one TVC on the bench and it was truly a disaster. It had extreme ringing with sq wave input on all settings but one. This particular unit came from China but wasn’t all that cheap. Be real careful of these and be sure you can return them for your money back if you don’t like them.
The stepped ladder looks real nice and at a fair price too. With only one resistor to the input at any settings it should be very nice sounding as well. Only disadvantage I can see is the large size.
Roger |
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| pcspinheiro |
There is a guy on ebay that sells those steped atenuators as a kit, you "just" need to solder all the resistors in place. The price is arround 30£ + P&P.
Thanks very much for all the buying tips! I'll look into it right now.
Paulo. |
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| Nuuk |
That's interesting! They were being sold on Ebay recently but you had to get them shipped over from the Far East. If they are exactly the same, they are a good buy even at the increased price! :att'n: |
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| pcspinheiro |
| The idea is good but wouldn't it be a bit exagerate to put a 50£ volume control on a <20£ amp :confused: ? |
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| MrDodo |
Hi,
I do think it makes sense to put a good pot on a good amp.
And of course the amp is worth more than 20 pounds when you consider the effort and time (and fun) in the soldering and assembly.
Good connectors by themselves may cost more than the amp.
And we are not talking about the power supply.
I have seen passive pre-amp with only input selector and attenuator in the $1000 price, so... |
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| Nuuk |
I agree with MrDodo here! Any hi-fi system is only as good as its weakest link!
I can think of lots of other things that will cost more than an attenuator and not improve the sound quality as much!
And besides, if you fit a 50 UKP volume control to a 20 UKP AMP-3 then surely you have a 70 UKP amp, not a 20UKP one. :att'n: ;) |
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| kanaddict |
What do you think of this one :
http://digitalanaloguediy.com/attenuator.html
they have a 10K and a 100K. I wonder if one of this value would be a good choice for the autocostruire 2020 kit ?
Nuuk
What is the value you use with your autocostruire amp ? |
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| kanaddict |
Are you satisfy of this unit ?
Thanks ! |
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| Nuuk |
| quote: | | What is the value you use with your autocostruire amp ? |
10K.
Those kits from OZ are a good price but I just went on their site and the total price at checkout did not show any shipping costs added. Is that right? Also, there is no method for paying by credit card! :( |
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| pcspinheiro |
| I just got a reply from the guy at diyfidelity and he said shipping to europe would be 8$ AUD meaning that it would cost the grand total of 35€! best price yet! The thing is he only accepts cheques or bank transfer... |
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| t. |
Those stepped attenuators using the dale resistors are nice units,
they are certainly much better than the Noble or Alps blue pots (already compared them).
I've just fitted mine inside a little case with in/out phono sockets and teflon/silver wiring, it makes a nice passive pre;) |
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| pcspinheiro |
A little question a bit off the topic... I can probably get hold of a thick aluminium plate that would be ideal for the front pannel of my on-going AMP3 based project. However, this material has an ugly, kind of polished finish.. how can I make it look like brushed aluminium? Just scrub it with coarse sand paper for metal? Any ideas?
Paulo. |
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| sx881663 |
Paulo,
There are many finishes you can do. One I like is to put a Scotch brite green scrub pad on an orbital sander and have at it. Place the panel on a rubber pad so it won’t move around while you sand it. Use even, straight across strokes to begin with. If you do use sandpaper start with 400, this is so it won't mess the panel up too much if you don’t like it. Working at metal finishing is a time consuming art and requires a great deal of patience. Doing it with a hand block and sandpaper will never be uniform but a hand finish can be done using the Scotch brite pads with a block. This finish won’t last and will start to deteriorate immediately, you will need to have it anodized when it is done to protect it. The finish will be smoother after the anodization as some of the surface etches away. A 600 finish will be almost shinny after it is anodized. An alternative after the finishing is done is to scrub it with dish soap and hot water, rinse very thoroughly in the hot water, dry, then do a transparent clear lacquer over coat. This is not very durable and I wouldn’t recommend it except for something quick and temporary.
Note; this is dirty work and will stain clothes. This will make your better half very unhappy so wear old ones.
Roger |
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| IndyAudi |
| quote: | Originally posted by Nuuk
Those kits from OZ are a good price but I just went on their site and the total price at checkout did not show any shipping costs added. :( |
I don't wish to confuse the issue but aren't those Oz stepped attenuators @ 49.5 AUD only mono ?
http://www.diyfidelity.com.au/produ...&products_id=32: |
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| kanaddict |
Well, it use a total of 90 resistors. It have 23 steps with 2 resistors each = 46 resistors. From this I can conclude that there is 45 for one channel and 45 for the other. I don't know why the stepped attenuator dont use 46 on each side :confused: Maybe someone can explain this to us :rolleyes:
Regards, |
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| sx881663 |
The top step needs no resistors, or just one to ground, as it is a direct connection input to output.
Roger |
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| MrDodo |
A little off topic not not much as we are in the pot subject, I've got an old Morganite 10k pot from the scrap bin and always wondered what was the connections at the back of the pot is for.
It's written 2A - 250v. |
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| sx881663 |
That is a power switch.
Roger |
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| MrDodo |
| Looks like there're used for power connections, but where's the switch. |
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| pcspinheiro |
If anyone is interested in the DIYfidelity resistors they do accept paypal payments. I'm getting one!:cool:
It seems to be stereo because on the second page of the assembly instructions it shows two in and two out pins, but there is only one ground... is this OK?
Oh, and thank you for the nice, detailed suggestions! |
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| theAnonymous1 |
Here is a link to a stepped attenuator that uses SMD resistors.
http://www.dact.com/html/attenuators.html
Looks nice, a bit pricey though at around $180 USD on the DIYcable site. They also sell a remote control attenuator kit for a whopping $405 USD :bigeyes:. |
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| vmac011 |
To IndyAudi
This is stereo attenuator
To Nuuk
I've checked on Australia Post site and postage (economy air) to UK is A$8. Same postage for US.
To Kanaddict
First step doesn't have series resistor, just 1 paralell to GND, thus 22*4+2=90
The attenuator is not silky smooth as DACT (in mechanical terms), but it's not bad either. Just a tad notchy. Sound is very,very good. It's mutch better than ALPS and lightyears ahead of any graphite pot. |
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| kanaddict |
| quote: | Originally posted by vmac011
To IndyAudi
The attenuator is not silky smooth as DACT (in mechanical terms), but it's not bad either. Just a tad notchy. Sound is very,very good. It's mutch better than ALPS and lightyears ahead of any graphite pot. |
Thanks for the information !
From what you said, I suppose that the mechanical lack don't have any effect on the sound. No noise when you turn the knob. It's more about the feeling you get when using it. |
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| Nuuk |
I've just ordered a 25K attenuator from DiyFidelity using Paypal! I doubt that there is any audible difference between the 25K version and the 10K that I have already but it's interesting to find out! ;)
Thanks to whoever originally spotted this great deal! :) |
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| pcspinheiro |
I ordered the 50K one because that's what Jan from 41 Hz (to whom I bought the AMP3 kit) says it's suitable... Should I just change my order? What difference can it make to have 10, 25 or 50 :confused: The sound volume will just increase faster or slower at each position of the attenuator or is there more to it? If someone can clarify this so that I can still chage my order if necessary, as they will only be shipping monday.
Thanks |
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| t. |
I wouldn't worry to much about the value, I've used 10,22,50 and 100k pots/Attenuators with my Amp3.
The 22k dale Attenuator sounded much better than a 10k or 100k pot:)
50k should be fine in my opinion |
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| Nuuk |
| I agree, 50K will be fine and I think 50K is the value of the pot supplied with the Autostriure amp" |
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| IndyAudi |
I like these PEC pots but I've only been able to find the 1 watt 20K mono military ones
as below.
If anyone can point me in the right direction for the 2 watt stereo ones I would be very
appreciative.
http://www.precisionsales.com/precomp.html |
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| kanaddict |
| quote: | Originally posted by vmac011
The attenuator is not silky smooth as DACT (in mechanical terms), but it's not bad either. Just a tad notchy. Sound is very,very good. It's mutch better than ALPS and lightyears ahead of any graphite pot. |
Could you please tell me what is the diameter of the attenuator (once the resistors are soldered). I have to verify if it will fit in the case I wanted to buy.
Thanks !
Daniel |
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| sx881663 |
| quote: | Originally posted by vmac011
The attenuator is not silky smooth as DACT (in mechanical terms), but it's not bad either. Just a tad notchy. Sound is very,very good. It's mutch better than ALPS and lightyears ahead of any graphite pot. |
I have found Dale resistors to be very clean and neutral sounding so am not surprised at your post.
Years ago the DACT attenuators also were very notchy. I fixed them by putting in lighter detent springs. Later Elma offered this as an option on there switches and DACT has used this lighter version ever since. I would think the same fix could be done to this switch. Just make sure the springs are equal if it uses 2 and strong enough to keep it from hanging between positions. While you have it open spray the inside liberally with WD40 and it will keep working properly for many years.
Roger |
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| vmac011 |
| quote: | | Could you please tell me what is the diameter of the attenuator (once the resistors are soldered). I have to verify if it will fit in the case I wanted to buy. |
The attenuator is aprox. 40-45mm in diameter. There are two ways of assembling.
1. as shown on DIYFidelity site http://www.diyfidelity.com.au/produ...&products_id=32
2. as per picture below. This way you save few MM in diameter. |
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| vmac011 |
Oops!
Forgot the picture. Here 'tis. |
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| kanaddict |
Thanks !
I'll ask them to solder it for me. They charge $20.40 AUD. Knowing me, it would take me more then hour to sorlder it and make sure that each value are at the right place. So, one hour of my time worth the extra $20.40 AUD :smash:
The attenuator would fit in the case I saw last fryday in a surplus store ($10) . It's a stong metal case that would need an appropriate face plate. For my GC chassis, I used a video recorder case and I made the face plate with wood and it look very good. This time I'm stugling with myself, doing the same kind of DIY chassis or buying a nice chassis. A DIY chassis would cost me about $30 and an aluminium chassis with the knobs would cost me about $130. Making the chassis, I would save $100, but the amp won't look so good :rolleyes: There is not much peoples who see my system....if I buy the nice chassis, it would be for my own pleasure ;)
Thanks again !
Daniel |
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| KT |
There was a very thorough discussion about these Dale-based attenuators a while back when everyone was making Gainclones.
A lot of folks got really excited about them because the offered very good performance for the price. As people started buying and using them, though, many discovered that the switch would often produce loud popping/ electrical switching noises when switched (and not necessarily at all rotational positions) that, when amplified, was sufficiently annoying that they eventually switched to something else. It was even determined that the switches were make-before-break types, so the culprit was thought to have been contact damage from excessive heat when the technician assembled them.
There was some fear, as well, that the loud pulse could damage high efficiency speakers.
I bought one of these before all this came to light, but I haven't had the chance to use it, yet.
It would be very useful to hear if anyone is still experiencing this type of popping on the more recent units being purchasing.
Apart from the popping, these attenuators were said to sound very good.
Best,
KT |
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| sx881663 |
The noise is generated from a voltage transient being generated and fed to the input. This can be caused by 2 things;
1) There is DC present on the volume controls input,
2) The switch opens up while switching between steps.
1 can be fixed by tracking it down and eliminating the source. A quick and dirty solution would be to add film caps into the path before the control.
2 can be fixed with a good replacement that doesn’t open up or a 27k res. can be added from the output to ground thus preventing it from ever opening all the way.
Roger |
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| soongsc |
| quote: | Originally posted by sx881663
I have found Dale resistors to be very clean and neutral sounding so am not surprised at your post.
Years ago the DACT attenuators also were very notchy. I fixed them by putting in lighter detent springs. Later Elma offered this as an option on there switches and DACT has used this lighter version ever since. I would think the same fix could be done to this switch. Just make sure the springs are equal if it uses 2 and strong enough to keep it from hanging between positions. While you have it open spray the inside liberally with WD40 and it will keep working properly for many years.
Roger |
Does the WD40 have good electrical characteristics? |
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| sx881663 |
I have been using the stuff for years in pots and on switches. It cleans and protects with just enough lubrication to be helpful but not enough to hurt conductivity. I have never had it hurt a part but have more than once saved a VC that didn't have an available replacement. It may have only lasted another year but better than nothing and certainly better than junking an otherwise good piece. I have not noticed it to have a sonic character but it is hard to tell as the sprayed part always sounds better after treatment. I also spray the internals of the DACT controls as a mater of course as they operate much smoother.
The only place you can get into a little trouble is if a switches detent requires grease and you wash it all off when you spray it.
As for electrical properties, they recommend it to spray wet auto ignition cables to disperse water. 30,000+ volts!
Roger |
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| MrDodo |
Quote
2 can be fixed with a good replacement that doesn’t open up or a 27k res. can be added from the output to ground thus preventing it from ever opening all the way.
Roger,
Is that a universal value res. or do I have to change the value if my pot is 50k to a 50k+ res? |
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| BWRX |
| Not to get off topic but that is quite an interesting use for WD40... When I worked at Clair Brothers Audio we used CAIG Deoxit on all metal contacts (pots, switches, etc) when servicing amps and input boxes. WD40 sure displaces water and lubricates well but I wonder how well it deoxidizes (if at all)? |
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| sx881663 |
1)The 27 k is a more or less arbitrary value that should work well in most applications. I would go to 50k for the higher value pots like 100, 250k. The idea is to be low enough to do the job without upsetting the log curve too much.
2)I have used a rather large assortment of cleaners over the years and don’t think any of them do much better than WD40 at cleaning. If you used one of the others you would want to restore the protection and lubrication anyway so why do 2 steps when one does just as well. The other thing with the other types of cleaners is I am not sure the residual left behind is benign. I would hate to find out the hard way by having a comeback.
Roger |
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| t. |
I've had one of those dale Attenuators for over a year now and have not experienced any problems with it at all
If you do get one of these I'd suggested wiring all the resistors up and running a sig gen through them for a while, I never believed resistors need burning in but the dales do benefit for some reason, I tried it and noticed an improvement
The case I use to house mine came from an old camera psu which cost me 50 pence from a radio rally
I just made a new front and back panel, well it does the job:D |
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| Nuuk |
| quote: | | This time I'm stugling with myself, doing the same kind of DIY chassis or buying a nice chassis. |
Hi Daniel, you may find something here to help make up your mind! ;)
Take it from me, the pods are ideal for the class-T amps! :att'n: |
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| vmac011 |
| quote: | | As for electrical properties, they recommend it to spray wet auto ignition cables to disperse water. 30,000+ volts |
People,
Please don't use it around HV cables and distributors in cars. I did it last week and it was misfiring badly (on great displeasure of other motorist during peak hour). From 280hp I was reduced to few asthmatic mule powers. Instead, use CRC or silicone spray. I guess it doesn't matter in low voltages.
| quote: | | It would be very useful to hear if anyone is still experiencing this type of popping on the more recent units being purchasing. |
No poping here baby! If you muck around Tripath amps, you should idealy de-couple with, say, >10uf poly cap. This is because the chip is internaly biased with 2.5VDC. I've asked people from DIY FIdelity if the switch is "make before break" type, but they didn't know. Lucky me, I work 2 blocks away from them. |
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| kanaddict |
t. and Nuuk,
thanks for showing me your chassis. They look great. I like woodworking and the pod would be fun to build, but I want a chassis that will contain both the amp and the PSU. So, I'll buy the $10 case I saw last Friday and make a nice front plate with wood or maybe with some black Plexiglas. I should be able to make it detachable. This will allow me to make a few front (Plexiglas) of different colour & change it from time to time.
I like Gold :$: & Red :car: and could try these for fun.
Let the fun begin :smash:
Daniel |
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| t. |
| quote: | Originally posted by kanaddict
t. and Nuuk,
thanks for showing me your chassis. They look great. I like woodworking and the pod would be fun to build, but I want a chassis that will contain both the amp and the PSU. So, I'll buy the $10 case I saw last Friday and make a nice front plate with wood or maybe with some black Plexiglas. I should be able to make it detachable. This will allow me to make a few front (Plexiglas) of different colour & change it from time to time.
I like Gold :$: & Red :car: and could try these for fun.
Let the fun begin :smash:
Daniel |
Yes, well have fun Daniel and don't forget to post some pictures;)
The advantage of having a seperate enclosed psu is it allows you to try out different supplies easier for comparing
Plus NUUKs pods look really smart:cool: |
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| kanaddict |
| quote: | Originally posted by t.
Yes, well have fun Daniel and don't forget to post some pictures;)
The advantage of having a seperate enclosed psu is it allows you to try out different supplies easier for comparing
Plus NUUKs pods look really smart:cool: |
I could try the Pod for the next project. I'll post some pictures and comments about the autocostruire kit in a few weeks. Here is a picture of my last project :
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| MrDodo |
I like the wood front, gives an organic feel to any project.
Can we see pic of the internals?
I also like the idea of seperate pieces that can be pluged together, just like Lego or if you are into programming, Java Beans.
I have started to do something that don't need cables between them, eg a DAC that plugs into passive pre that plugs into power amp side by side. This way I can swap the passive for another one to see if it's better.
Only constraint, these beans must be small enough to be able to be plugged side by side and still stand on a standard shelf.
41hz amp3 , monica2 DAC and passive pre are ideal candidates for audio beans.
I'll post some pics as and when these can be shown.
Cheers,
Thierry. |
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| t. |
| quote: | Originally posted by kanaddict
I could try the Pod for the next project. I'll post some pictures and comments about the autocostruire kit in a few weeks. Here is a picture of my last project :
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Nice work Daniel:cool: |
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| Nuuk |
| Yes, nice work and a beautiful piece of wood! :checked: |
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| kanaddict |
| quote: | Originally posted by MrDodo
I like the wood front, gives an organic feel to any project.
Can we see pic of the internals?
I also like the idea of seperate pieces that can be pluged together, just like Lego or if you are into programming, Java Beans.
I have started to do something that don't need cables between them, eg a DAC that plugs into passive pre that plugs into power amp side by side. This way I can swap the passive for another one to see if it's better.
Only constraint, these beans must be small enough to be able to be plugged side by side and still stand on a standard shelf.
41hz amp3 , monica2 DAC and passive pre are ideal candidates for audio beans.
I'll post some pics as and when these can be shown.
Cheers,
Thierry. |
Yes, wood ad some warmth to a piece of electronic. Most modern amp look cold. I bought an antique radio last week (tubes) mostly because of the nice wood they used. It's my second antique radio, last years I got a nice 1938 Zenith. These radio are piece of art and are part of the audio history.
About the pictures of the internals, I don't have some...mainly because it is not as well done as it should be. It was my first project and I had to deal with the video recorder case. The amp look good externally, but the inside is far from being a reference :(
Regards, |
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| kanaddict |
| quote: | Originally posted by t.
Nice work Daniel:cool: |
| quote: | Originally posted by Nuuk
Yes, nice work and a beautiful piece of wood! :checked: |
Thanks guy !
I have some leftover of this wood and will probably use it for my actual project (autocostruire kit). I want to try plaxiglass before, to see how it look. By the way, I used Tung oil to protect the wood. |
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| MrDodo |
Daniel,
Acrylic and wood looks nice, particularly dark wood.
See my attempt at making the smallest case for amp3, and having shortest length of cable to sockets. Top is acrylic, side wood and bottom aluminium, which also serve as heatsink. Sorry, pic is not very good. My inablilty to take a good pic, not the camera's fault.
Thierry. |
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| pcspinheiro |
Well, I'm back again... I received my AMP3 kit and have soldered almost everything in place except for the chip. Soldering, however, is not first class :( ... (meaning that it is not always the "by the book" concave shinning surface type, sometimes it's a bit more messier)... but everything seems well soldered. My inexperience in soldering SMD components for one and the not so thin tip of the iron are to blame (that is why I could not solder the chip...). Will there be adverse effects of this soldering, I mean, nasty even, on the sound quality or will it just look worst than if done by a pro? That is, if I didn't burn any of the components :hot: (does this happen easilly?)...
Regretably late, I'm getting a new welding iron with finer tip for soldering the tripath chip. Regarding the PSU that I talked about, welll... I tore it apart but there seems to be no output regulator so I'll be using the (measured) 12.34V. Will it be necessary to add a heatsink to the chip?
Cheers,
Paulo P |
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| pcspinheiro |
Just finished building my diyfidelity stepped attenuator and it looks great! Still haven't soldered the chip yet though as I can't seem to find a fine tipped solder iron that doesn't cost a lot of money...
I'll try ebay... otherwise I'll just pay some repair shop to do it for me. |
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| dnsey |
| quote: | | I can't seem to find a fine tipped solder iron that doesn't cost a lot of money |
If you have a 'named' (Antex, Weller, etc.) iron, you should be able to obtain a fine tip for it with little difficulty. |
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