Aleph 5 with no (few) gain

ElectroNick · 12th March 2005, 04:29 PM

Hi,

The past week i've been testing the A5 amp. One channel gives 16 mV at output at works fine.
But.... the other one seems to have no gain. While inspecting both channels i found that at the base of Q5 (T4 in the Kristian schematic) there was a lot of noise on the signal. The signal itself is not amplified, in the other, good mono section you can see a larger signal.

The only thing i recall the past week, while switching between both channels., i heard some "spikes" while connecting the speaker to the bad amp.

So far i changed C10 and Q5 (T4 and C3 in the Kristian schematic)

What can it be, i'm getting confused.

Am i looking in the wrong place, i mean is some other component responsible for the trash signal on the base of Q5 ?

Phill · 12th March 2005, 06:45 PM

hello

I am sorry to be able to answer your question ...

I visited your Web page ...

can you explain this image

which are the components used?
thank you
Phill

Netlist · 12th March 2005, 07:58 PM

Does the diff pair work?
What DC values do you get at the crucial points? VCE Q5, voltage over R14, is there bias current flowing trough the outputs?

/Hugo

ElectroNick · 13th March 2005, 12:41 PM

I found the error

It seems that i drilled through a trace when i was placing the three capacitors, they had a different size.
I soldered the caps but overlooked the missing trace

Anyway : a simple repair on the PCB and the Aleph was working.
I'm now building it together again and in an hour or so i'll sit back and relax (maybe with some wine

)

Grtz
Nick

ps : @ Phil
It's a simple discrete rectifier with MBR1645 and some MKS caps.

ps2 : i'm not using this bridge at the moment, for now only a "simple" metall rectifier bridge.

Netlist · 13th March 2005, 01:08 PM

/Hugo

12th March 2005, 04:29 PM	#1
ElectroNick diyAudio Member Join Date: Dec 2002 Location: The Netherlands	Aleph 5 with no (few) gain Hi, The past week i've been testing the A5 amp. One channel gives 16 mV at output at works fine. But.... the other one seems to have no gain. While inspecting both channels i found that at the base of Q5 (T4 in the Kristian schematic) there was a lot of noise on the signal. The signal itself is not amplified, in the other, good mono section you can see a larger signal. The only thing i recall the past week, while switching between both channels., i heard some "spikes" while connecting the speaker to the bad amp. So far i changed C10 and Q5 (T4 and C3 in the Kristian schematic) What can it be, i'm getting confused. Am i looking in the wrong place, i mean is some other component responsible for the trash signal on the base of Q5 ?

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12th March 2005, 06:45 PM	#2
Phill diyAudio Member Join Date: Nov 2003 Location: France dand le sud	hello I am sorry to be able to answer your question ... I visited your Web page ... can you explain this image which are the components used? thank you Phill

12th March 2005, 07:58 PM	#3
Netlist diyAudio Moderator Emeritus Join Date: Jan 2003	Does the diff pair work? What DC values do you get at the crucial points? VCE Q5, voltage over R14, is there bias current flowing trough the outputs? /Hugo

13th March 2005, 12:41 PM	#4
ElectroNick diyAudio Member Join Date: Dec 2002 Location: The Netherlands	I found the error It seems that i drilled through a trace when i was placing the three capacitors, they had a different size. I soldered the caps but overlooked the missing trace Anyway : a simple repair on the PCB and the Aleph was working. I'm now building it together again and in an hour or so i'll sit back and relax (maybe with some wine ) Grtz Nick ps : @ Phil It's a simple discrete rectifier with MBR1645 and some MKS caps. ps2 : i'm not using this bridge at the moment, for now only a "simple" metall rectifier bridge.

13th March 2005, 01:08 PM	#5
Netlist diyAudio Moderator Emeritus Join Date: Jan 2003	/Hugo