Hey guys, I just got a Hartke lh1000 and there’s a switch in the rear that switches from bridge to dual parallel modes but the switch is recessed into the chassis to the point where you have to use a pen or key or something to access it and switch it. Is this a defect or is this the way it’s designed. It doesn’t say anything about it in the manual and it just doesn’t look right to me. Thanks
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Hartke lh1000 bridge switch
- Thread starter bear33
- Start date
- Feb 12, 2006
- 60,953
- 5
- 220,608
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
This is absolutely by design, and imo a good design.
Something else not in the manual. Don’t shift the switch with the power on.
Remember that in bridge if you use a 1/4" Phone plug that both the tip and the sleeve are hot with respect to ground. It's very easy to get a shock from the speaker cable! 
On amps that are switching the input from the preamp, it could avoid a loud pop which isn't good for your speakers. The design may prevent this but it's good to be safe.
Bridge switches should be hard to actuate - it's not a switch you want to accidentally engage or disengage, as it changes how the thing works fundamentally, and there are....potential consequences to being in the wrong mode; hence having them out of the way is a great idea.
It's not quite as serious as the switch you use for launching a nuclear missile, but in audio, a bridge switch on a power amp is about as serious as we get.
It's not quite as serious as the switch you use for launching a nuclear missile, but in audio, a bridge switch on a power amp is about as serious as we get.
I have an Eden WT500/800 which was upgraded to 400-watts per channel @ 4ohms and 800-watts bridged. It also has that recessed bridge switch, which is a good thing. It ensures that you are paying attention to what you are doing and that the change in mode is deliberate.
One other thing that might not be in the manual is to center the balance knob when you are running in bridged. What the amp is doing is taking all the power from one power section and sending it over to the other power section (bridging it) which is then sent to the bridged output. If you turn the balance knob towards the side that is sending the power, there won't be anything there. So it will get quieter and quieter until it's gone. Turn it back to center and all the power is there. Turn it towards the side that is getting all the power and it will sound the same as having it centered. So be sure to just set it at center when you run it bridged.
Another thing to be careful of is DO NOT plug anything into either the left or right side when running in bridged mode. ONLY use the bridged speakon output on the back of your amp in bridged mode. All kinds of bad things can happen if you have cabs plugged into the wrong jacks when running bridged...none of it good.
One other thing that might not be in the manual is to center the balance knob when you are running in bridged. What the amp is doing is taking all the power from one power section and sending it over to the other power section (bridging it) which is then sent to the bridged output. If you turn the balance knob towards the side that is sending the power, there won't be anything there. So it will get quieter and quieter until it's gone. Turn it back to center and all the power is there. Turn it towards the side that is getting all the power and it will sound the same as having it centered. So be sure to just set it at center when you run it bridged.
Another thing to be careful of is DO NOT plug anything into either the left or right side when running in bridged mode. ONLY use the bridged speakon output on the back of your amp in bridged mode. All kinds of bad things can happen if you have cabs plugged into the wrong jacks when running bridged...none of it good.
