Hi folks,
Need your advise.... Thanks to the excellent instructions on Mike Mardis's website, I have successfully completed the "stealth" mod. 😀
BUT... for some reason, there is this constant "hissing" sound on the speakers. It is really faint (barely audible unless ears next to it) and does not increase with the turning of the pot (I'm using 100K Alps Pot). But, the "hissing" sound does get real loud when I touch the pot. I tried touching the cap and cables... no sudden amplification.
I'm using a single ground cable to the pot. It is wired to both L & R terminals on the pot. The ground from the RCAs then tap from this same point on the pot's terminal.
I have since resoldered the terminals on the PCB and ground cables on the pot. But does not make any difference...
Anyone has similar encounter? What else do I need to check? 😕 Thanks in advance...
Need your advise.... Thanks to the excellent instructions on Mike Mardis's website, I have successfully completed the "stealth" mod. 😀
BUT... for some reason, there is this constant "hissing" sound on the speakers. It is really faint (barely audible unless ears next to it) and does not increase with the turning of the pot (I'm using 100K Alps Pot). But, the "hissing" sound does get real loud when I touch the pot. I tried touching the cap and cables... no sudden amplification.
I'm using a single ground cable to the pot. It is wired to both L & R terminals on the pot. The ground from the RCAs then tap from this same point on the pot's terminal.
I have since resoldered the terminals on the PCB and ground cables on the pot. But does not make any difference...
Anyone has similar encounter? What else do I need to check? 😕 Thanks in advance...
Can you post photos and diagram of your wiring?
It is probably a grounding or shielding issue, but it is hard to tell ithout seeing it.
It is probably a grounding or shielding issue, but it is hard to tell ithout seeing it.
Here goes.... first time posting pictures.. hopefully it comes out fine... thanks!
Btw, I read in one of the thread that high DC offset is bad. It should not exceed 100mV. How do we measure that? Probe the +ve and -ve of each set of speaker binding post? What can we do if it exceeds 100mV? Thanks!
Btw, I read in one of the thread that high DC offset is bad. It should not exceed 100mV. How do we measure that? Probe the +ve and -ve of each set of speaker binding post? What can we do if it exceeds 100mV? Thanks!
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Shielded cable for all the low level signal leads would probably help a lot. Make them as short as possible.
Also move the speaker leads well away from the input leads.
Cheers
Rob
Also move the speaker leads well away from the input leads.
Cheers
Rob
Hi Rob,
Low level signals refer to the input? I will try using copper braids. Does this goes back to supply ground (as in 110/240v earth), the 12V ground (or 0v), or the digital ground that the inputs are going to? 😕
Chances is that I cannot shorten the cable anymore coz I will be re-housing this into a fairly long wooden box... 🙂
Do I need to shield the output/speaker cables as well?
Thanks!
Low level signals refer to the input? I will try using copper braids. Does this goes back to supply ground (as in 110/240v earth), the 12V ground (or 0v), or the digital ground that the inputs are going to? 😕
Chances is that I cannot shorten the cable anymore coz I will be re-housing this into a fairly long wooden box... 🙂
Do I need to shield the output/speaker cables as well?
Thanks!
Hi
I assume you mean by "copper braids", the shielding around the cable. Just connect it to the same place as the existing black wires. Shielding the input leads should be sufficient as long as you keep the speaker leads well away from them.
Cheers
Rob
I assume you mean by "copper braids", the shielding around the cable. Just connect it to the same place as the existing black wires. Shielding the input leads should be sufficient as long as you keep the speaker leads well away from them.
Cheers
Rob
Rob is right, you need to clean up your wiring. Keep everthing as short as possible and use sheilded cable for the inputs. Keep the speaker wires away from the input wires.
As far as I can see, all the connections are correct.
That's a mighty big power supply you have there!! 😱
As far as I can see, all the connections are correct.
That's a mighty big power supply you have there!! 😱
Heh...heh... that's a SMPS I bought off some second-hand shop.. think is a 75W power supply. Comes with both 12v and 5v... I tuned the pot within the SMPS to supply 12.8v. So far still hanging on... 🙂
I will try the shielding of the input cables first. But strangely, how does my hand touching the potentiometer's shaft (I have yet to put in a knob) or it's metalic surface amplifies the ringing sound? 😕
Will update once I'm done with the grounding... 🙂
Thanks!
I will try the shielding of the input cables first. But strangely, how does my hand touching the potentiometer's shaft (I have yet to put in a knob) or it's metalic surface amplifies the ringing sound? 😕
Will update once I'm done with the grounding... 🙂
Thanks!
Btw, I also noticed the output (music) seems to have either being attenuated or there seems to be loss of dynamics... 😕 I now need to turn the pot much higher to achieve similar loudness... how come?
Anyway, here's the pic of the final product... i used heat-shrink to wrap each pair up and it's connected on 1 end to the gnd on the pot:
Anyway, here's the pic of the final product... i used heat-shrink to wrap each pair up and it's connected on 1 end to the gnd on the pot:
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Okay you seem duely distressed.
1) I got hiss and hum before in an enclosed casing, had to rewire the wires, try braiding them. But yours is an open casing, so it may not pertain to you yet. Shielded wire maybe overkill for this application.
2) I got distortion on one channel, it bugged me out until i discovered it was actually bad cap.
3) Assuming you has properly isolated all binding post and rca jacks already, tie only* signal in* ground to chassis and make sure the rest is floated. Try some teflon plumber tape if you are unclear if there proper isolation.
4) Check the board for any soldering gone wrong. Its another highly likely cause, so use a fine tooth comb.
5) Have you heard of Koba in Chinatown, you can get tons of stuff to mod the board even more! They have nichicon, elnas, inductor that look like 41-hz clones prewired.
Regards
Chuck.
PS worst come to worst, look for someone on the echoloft forums to check the board out for you.
1) I got hiss and hum before in an enclosed casing, had to rewire the wires, try braiding them. But yours is an open casing, so it may not pertain to you yet. Shielded wire maybe overkill for this application.
2) I got distortion on one channel, it bugged me out until i discovered it was actually bad cap.
3) Assuming you has properly isolated all binding post and rca jacks already, tie only* signal in* ground to chassis and make sure the rest is floated. Try some teflon plumber tape if you are unclear if there proper isolation.
4) Check the board for any soldering gone wrong. Its another highly likely cause, so use a fine tooth comb.
5) Have you heard of Koba in Chinatown, you can get tons of stuff to mod the board even more! They have nichicon, elnas, inductor that look like 41-hz clones prewired.
Regards
Chuck.
PS worst come to worst, look for someone on the echoloft forums to check the board out for you.
Plus you still have unshielded wires from the pot to the caps and from the caps to the board.
Cheers
Rob
Cheers
Rob
Hi angchuck,
What do you mean by "signal in to ground and float the rest"? 😕 Anyway, I will pop by koba next week... 😀
Hi all,
Thanks for all your advise.... here's what I have done and the result.... (in order of the tries)
1. copper shielding (only on input...left out the ones on the input caps... 🙁 )
-> becomes softer, less dynamic
-> ringing still exist
2. insert stiffener cap
-> ringing still exist
3. ground pot chassis and psu chassis to supply ground
-> ringing still exist
4. re-solder smts whose soldering looks dodgy
-> ringing seems to have more subdued but still exist
Actually, I realised that it can be rather intermittent. It can disappear/reappear after playing a little while. I'm gonna try my friend's SMPS some time soon. Just in case it is a case of noisy PSU.
Anyway, I dun think will be putting in the braid shielding.. didn't quite like how it sounded after that. 🙁 Anyway, will get the replacement cap for C10 and the inductors before troubleshooting further... hopefully it is a faulty component... 😀 Err... you guys think the pot/EMI filter might be the culprit?
Btw, here's a pic of the new "housing", with integrated SMPS, using an input receptacle with EMI filter. 😉 Still "al-fresco" style... easy to change components. Will put a cover after that. 😀
Thanks
What do you mean by "signal in to ground and float the rest"? 😕 Anyway, I will pop by koba next week... 😀
Hi all,
Thanks for all your advise.... here's what I have done and the result.... (in order of the tries)
1. copper shielding (only on input...left out the ones on the input caps... 🙁 )
-> becomes softer, less dynamic
-> ringing still exist
2. insert stiffener cap
-> ringing still exist
3. ground pot chassis and psu chassis to supply ground
-> ringing still exist
4. re-solder smts whose soldering looks dodgy
-> ringing seems to have more subdued but still exist
Actually, I realised that it can be rather intermittent. It can disappear/reappear after playing a little while. I'm gonna try my friend's SMPS some time soon. Just in case it is a case of noisy PSU.
Anyway, I dun think will be putting in the braid shielding.. didn't quite like how it sounded after that. 🙁 Anyway, will get the replacement cap for C10 and the inductors before troubleshooting further... hopefully it is a faulty component... 😀 Err... you guys think the pot/EMI filter might be the culprit?
Btw, here's a pic of the new "housing", with integrated SMPS, using an input receptacle with EMI filter. 😉 Still "al-fresco" style... easy to change components. Will put a cover after that. 😀
Thanks
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okay... last ditch efforts to rid the ringing sound... 😛
1. Changed C10 to 2200uF Elna (is this too big?)
2. Changed the stock inductors to some other bigger coil ones...
- measured at the shop... was 11uH... how does it being a little bigger than the 10uH suggested by Tripath affect the output?
- the highs seems a little "truncated"... less dynamic too... 😕
- What's the purpose of these output inductors? Noise reduction?
The sound seems a lot more tamed... actually, it happens alot lesser now.. though it still comes back once in a while... similar loudness as before when it happen actually... will run it a little longer before changing anymore stuff.... 😛
Thanks...
1. Changed C10 to 2200uF Elna (is this too big?)
2. Changed the stock inductors to some other bigger coil ones...
- measured at the shop... was 11uH... how does it being a little bigger than the 10uH suggested by Tripath affect the output?
- the highs seems a little "truncated"... less dynamic too... 😕
- What's the purpose of these output inductors? Noise reduction?
The sound seems a lot more tamed... actually, it happens alot lesser now.. though it still comes back once in a while... similar loudness as before when it happen actually... will run it a little longer before changing anymore stuff.... 😛
Thanks...
Hi folks,
The ringing sound seems to be solved liao.... tried quite a few things until stumble on the ONE... 🙂
1. Shielding + grounding for input caps (wima mkp)
- improves but still significant
2. Shielding + grounding for pot
- waste time... no difference!
3. Attached a grounding cable to silvery top of cap C10 (onboard cap)
- Clears up immediately!
Really strange... before I change the stock cap to Elna 2200uF CEW, ringing sound already there. Could it be 2 cases of bad caps? I will probably try another cap when I make more changes... status quo for now... 😛 Anyone experience ringing noise due to the same issue? 😕
Thanks!
The ringing sound seems to be solved liao.... tried quite a few things until stumble on the ONE... 🙂
1. Shielding + grounding for input caps (wima mkp)
- improves but still significant
2. Shielding + grounding for pot
- waste time... no difference!
3. Attached a grounding cable to silvery top of cap C10 (onboard cap)
- Clears up immediately!
Really strange... before I change the stock cap to Elna 2200uF CEW, ringing sound already there. Could it be 2 cases of bad caps? I will probably try another cap when I make more changes... status quo for now... 😛 Anyone experience ringing noise due to the same issue? 😕
Thanks!
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