Speaker output volume very low please help!

[admin_exported]

Hello

I have a problem with my new hifi setup that consists of a Rotel RB-1070 Power amp, Rotel RC-1070 Pre and a pair of B&W P4 floorstanding speakers.

I bought them all second hand from various sources and have finally got round to connecting them up.

The first problem i encountered was there seemed to be no sound from the amp so i opened it up and tested the fuses. One of the four fuses was bad so i replaced them all with new ones.

After trying again I thought it might work but it did not. I thought there was no sound at all coming through so i turned up the volume dial and when it got to full volume I could hear sound coming out of the speakers but it is very very quiet but both speakers work.

So this is where I am stuck, does anyone know what could be wrong?

I have tried different interconnects from pre to power, did'nt make any difference.

I don't think it can be the speaker cables as there is sound going to the speakers.

I have tried a cd player and turntable but both are low volume.

Could it be a problem with the power amp?

Any advice please?

much appreciated,

 

[Covenanter]

It sounds pretty much as if the power amp isn't working (although it is impossible to be sure about the preamp). The fact that one of the fuses had gone is indicative that something happened in the past.

Chris

 

[Anonymous]

Did you change the fuse of the pre or poweramp?

 

[Anonymous]

Hi

Thanks for your reply, I changed the 4 fuses that were in the power amp, when I turn it on the power light comes on and the fuses do not blow.

I checked the fuse inside the pre-amp also but it was fine anyhow.

I'm wondering if it's a problem with the pre but also suspect the power amp.

 

[Covenanter]

The fuses in power amps are there to protect the output stages should you, for example, short out the speaker ports. They don't always work fast enough and then the output transistors can get fried. That's where the evidence points.

Chris

 

[Crocodile]

Check the jumpers are set to stereo mode & not bridged mono as per the manual.

Try headphones on the pre-amp, that should give an indication if it's working.

 

[Anonymous]

Thanks for the reply, so you think that if i replace all of the output transistors it should work normally again? Are they attached to the heatsinks?

Thanks again!

 

[Overdose]

They will most likely be screwed to the heatsinks. I'd test them first though. If replacing, make sure you replace like for like and don't be tempted to 'upgrade' them. I think that you'd be unlucky to have all four transistors fried, more often just one channel is affected. Have a look at the wiring diagram and see what part of the amplifier was protected by the blown fuse, this would be the first place I'd start looking.

 

[Anonymous]

Thanks again, any advice for a newby with a digital multimeter to test the transistors without getting fried?

But if only one channel maybe faulty then why does sound still come through both speakers but at very very low volume?

I have also checked the jumpers and they are in the correct positions.

I plugged my headphones into the pre-amp and sound came through like normal.

thanks

 

[Overdose]

I wouldn't rule out the transitors being fried, but I wouldn't expect them to be.

Without wanting to sound off, if you don't know how to test a transistor, perhaps you shouldn't be tinkering inside the amp?

Anyhow, have a read of this... just be aware that a little knowledge can be a dangerous thing. I would first get hold of a wiring schematic for the amp though and work through before digging in with test probes and the like. If nothing else, you'll get a better idea of what you are dealing with.

 

[Anonymous]

Yes I would not consider poking about inside so would leave it to the pro's it's far too dangerous.

I think i'll take it to the repair shop.

Thanks for all the help :rockout:

 

[hybridauth_Facebook_10154067646864728]

I nave similar problem with second hand amp (pioneer A-204R), worked fine then volume went very low after trying a different set of speakers, thought it was the speakers so reconnected the origonal speakers and the volume is still very low. Has any body heard of protection mode? If so, how is it reset? I've heard that if an amp is 'blown' then there wouldn't be any sound.