Hi all,
I got this amp second hand, it was not used for some years. I really like it, but I wanted to connect a subwoofer amplifier to the PreOut, but there is no signal there.
Is there something I need to do to have a signal there? The manual mentions muting circuit - could it be that there is a bad relay or something?
The funny thing is that my colleague's amp behaves exactly the same - no signal on the PreOut - so either it is a common weakness/failure or I am doing something wrong. From the manual's description, I would expect to have line level signal that I listen to controlled by the volume. I tried to use the recording outputs for the subwoofer, but that means constant volume readjustment since the level on rec out is not influenced by the main volume or input selector.
Is there any owner of this amp that could confirm the way the PreOut works?
Thanks!
I got this amp second hand, it was not used for some years. I really like it, but I wanted to connect a subwoofer amplifier to the PreOut, but there is no signal there.
Is there something I need to do to have a signal there? The manual mentions muting circuit - could it be that there is a bad relay or something?
The funny thing is that my colleague's amp behaves exactly the same - no signal on the PreOut - so either it is a common weakness/failure or I am doing something wrong. From the manual's description, I would expect to have line level signal that I listen to controlled by the volume. I tried to use the recording outputs for the subwoofer, but that means constant volume readjustment since the level on rec out is not influenced by the main volume or input selector.
Is there any owner of this amp that could confirm the way the PreOut works?
Thanks!
in case you change your mind and with a beer and a little patience 
View attachment hfe_denon_pma1500ae_schematics.pdf
View attachment hfe_denon_pma1500ae_schematics.pdf
I have tried to look at the diagram and if I am correct, both the headphone output and pre-out are actually powered from the speaker terminals - the pre-out is just a simple resistor voltage divider. So I just replicate the pre-out circuit board and use it as my new pre-out connected to the Speaker B terminals.
This actually brings me to an idea - both amps were bought at the same dealer - and disconnecting the pre-out board could have been some "tuning" thing or, since they are from the same series, the operator forgot to put the plug in on Friday afternoon or something like that
If there is a failure, then it is definitely in the switching circuit, otherwise it would not play at all.
huggygood, a million thanks for help!!!
This actually brings me to an idea - both amps were bought at the same dealer - and disconnecting the pre-out board could have been some "tuning" thing or, since they are from the same series, the operator forgot to put the plug in on Friday afternoon or something like that
If there is a failure, then it is definitely in the switching circuit, otherwise it would not play at all.
huggygood, a million thanks for help!!!
As long as it still plays as good as it does now, I will not open it. However, I have noticed another flaw. When playing really at low volume, the L and R channels are very unbalanced to a point, where the right does not play at all. That is on whisper level volume. Not too surprising, due to the construction.
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