Duck-Twacy said:Oops 220VAC... (zo zie je maar, haastige spoed is ...)
/* english mode on :
Well, i wanted to write +/- 10 % but than i ran out of aluminium
Duck-Twacy said:
It's free, just like the laser-engraving !
Ehhh, yeah.... something like thatJacco Vermeulen said:Maybe he wants to tell people he already has the amplifier for years and years, pointing to the voltage label.
I mean two years ago is was 220 V, right ?
Humming problems !
Just survived the first week listening to the A5 amp.........
Sound is oke, but....
As the amp gets warmer
the 50 Hz becomes louder. However, when playing the humming isn't that audible, but i just don't like it.
What could be the reason ?
The power supply i now use is for a stereo A5 :
1 x 625 VA
2 x diode bridge (regular types)
4 x 47000uF
4 x 10uF
Case isn't grounded and not connected with a NTC.
Grtz,
Nick
Just survived the first week listening to the A5 amp.........
Sound is oke, but....
As the amp gets warmer
the 50 Hz becomes louder. However, when playing the humming isn't that audible, but i just don't like it.What could be the reason ?
The power supply i now use is for a stereo A5 :
1 x 625 VA
2 x diode bridge (regular types)
4 x 47000uF
4 x 10uF
Case isn't grounded and not connected with a NTC.
Grtz,
Nick
Hi,
can you hear the 50Hz in the speakers or is it mechanical hum?
To test for the last just disconnect your speakers and listen.
The mechanical hum can be bettered by using a dc-filter on the primaries and decoupling the transformers (rubber...)
If you can hear it through the speakers you must have a look at the earthing. The case should be connected to ground (at least the ground between the caps as mains ground normally isn´t used in dutch living rooms).
William
can you hear the 50Hz in the speakers or is it mechanical hum?
To test for the last just disconnect your speakers and listen.
The mechanical hum can be bettered by using a dc-filter on the primaries and decoupling the transformers (rubber...)
If you can hear it through the speakers you must have a look at the earthing. The case should be connected to ground (at least the ground between the caps as mains ground normally isn´t used in dutch living rooms).
William
William,
It's 50 Hz hum in the speaker.
Today i tried grounding case and 0V, no result.
Should i start thinking about a CRC power supply ?
I hoped the "standard" aleph power supply would be enough
Or should i add some extra supply caps, eg 2x68000uF ???
Grtz
Nick
ps : i'm not a fan of connecting amps to the mains ground, too much trash on that line.....
It's 50 Hz hum in the speaker.
Today i tried grounding case and 0V, no result.
Should i start thinking about a CRC power supply ?
I hoped the "standard" aleph power supply would be enough
Or should i add some extra supply caps, eg 2x68000uF ???
Grtz
Nick
ps : i'm not a fan of connecting amps to the mains ground, too much trash on that line.....
Nick,
if it´s 50Hz then it won´t be the power supply ripple ( 100 Hz) but normaly some kind of ground loop or transformer induced hum.
Try moving the cables inside your amp while listening to the hum. Maybe you can get rid of it this way.
What is kind of funny is that it get´s worse when the amp warms up. This could mean that a connection or solder joint is bad......
William
if it´s 50Hz then it won´t be the power supply ripple ( 100 Hz) but normaly some kind of ground loop or transformer induced hum.
Try moving the cables inside your amp while listening to the hum. Maybe you can get rid of it this way.
What is kind of funny is that it get´s worse when the amp warms up. This could mean that a connection or solder joint is bad......
William
E-Nick,
I think your 625VA power transformer for a stereo A5 is sweating it out causing it to hum. If your speakers are demanding it to work to Class AB, the original AC current gain setting of the A5 at about 75% might be too high and is taxing your PS transformer. Try reducing the ACIG to about 65% or replacing your x'former. Try the first as it's easier and less expensive.
I think your 625VA power transformer for a stereo A5 is sweating it out causing it to hum. If your speakers are demanding it to work to Class AB, the original AC current gain setting of the A5 at about 75% might be too high and is taxing your PS transformer. Try reducing the ACIG to about 65% or replacing your x'former. Try the first as it's easier and less expensive.
Well Blues,
Today i disconnected one channel to see what would happen.
...............It didn't help. There's still a humm.
Next i'll dissamble the amp to see what happens when the trannie is further away from the PCB's
Maybe if i cut the bridge between GND and -IN the amp won't pick up hum so easily.
Grtz
Nick
ps : @WuffWaff the increase in hum due to temperate increase is minimal. It's not so that in "cold" state the amp doesn't hum.
Today i disconnected one channel to see what would happen.
...............It didn't help. There's still a humm.Next i'll dissamble the amp to see what happens when the trannie is further away from the PCB's
Maybe if i cut the bridge between GND and -IN the amp won't pick up hum so easily.
Grtz
Nick
ps : @WuffWaff the increase in hum due to temperate increase is minimal. It's not so that in "cold" state the amp doesn't hum.
Try to use some thin copper plate between the pcb and the transformer (a4 format available by bruna, or copper strip available by conrad). Can you tell me the transformer type ( amplimo?) Take some pictures of the inside, and post them.
I've 2 stereo aleph 5 and the sound great, no buzz at all, only a mechanical buzz in the first 10 minutes from the trafo.
Trafo 625 VA
6x22.000 UF cap
Also measure the fets, and compare the DC voltage over the 1 ohm resistor. Did you use a bypass cap over Z5 ?, do you use a variable resistor for R19. Measure the ac current over the power supply wire. Do you use MKP for example 2.2 UF over the power supply caps? Have you already connected the input ground on the aluminium case ?
Berry
I've 2 stereo aleph 5 and the sound great, no buzz at all, only a mechanical buzz in the first 10 minutes from the trafo.
Trafo 625 VA
6x22.000 UF cap
Also measure the fets, and compare the DC voltage over the 1 ohm resistor. Did you use a bypass cap over Z5 ?, do you use a variable resistor for R19. Measure the ac current over the power supply wire. Do you use MKP for example 2.2 UF over the power supply caps? Have you already connected the input ground on the aluminium case ?
Berry
@Berry :
I'll check if there's AC over Z5. That looks an easy modification.
@ all
I'm a bit disappointed, my brother built an A40. Inside it looks like spaghetti, but no hum
I'll let ya'll know soon what happened...
Grtz,
Nick
It's a 625VA 2x30V modified to 2x28V
Ehhh, no !
Nope !
Some bypass caps, but no MKP's
Yes, with a thermistor and a 10 Ohm resistor.
I'll check if there's AC over Z5. That looks an easy modification.
@ all
I'm a bit disappointed, my brother built an A40. Inside it looks like spaghetti, but no hum
I'll let ya'll know soon what happened...
Grtz,
Nick
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