Question about bridge mode on my amp

[autodidact]

Sorry if this has been asked 100 times but most of the bridge posts I find are too confusing for a simpleton like me to understand -_-"

Question is: in "bridge mode" my Hartke LH1000 puts out either 1000 or 1100 Watts, I forget which. Anyways if I have a 600w cabinet and an 800w cabinet both running off the head could I run it in "bridge" mode? Would the volume really be that much more substantial?

[LiamPodmore]

The bridge mode will likely only be an 8 ohm minimum load, so no, you couldnt run bridge with 2 cabs (As far as i know) but you could with 1.

Liam

[Dark Barn]

What is the impedance rating of these 2 cabs? If they are both 4 ohm for example you might have issues trying to run them in series. Do either of the cabs have a through out?

Ignore how many watts the cabs are rated for, that's the last of your concerns.

[steveksux]

You need to know the minimum impedance the amp will drive in bridge mode, and the ohm rating of the two speakers. If the amp will drive a 4 ohm load in bridge mode (not all that common, it would have to be ok with a 2 ohm load on both channels when run in stereo mode), and both speakers are 8 ohms, you'd probably be ok.

The 1000 or 1100 watts would divide equally between the 2 8 ohm cabs, resulting in around 500-550 watts RMS so you won't be in imminent danger of blowing the speakers. You could actually even use a little more power, many recommend using an amp rated at 1.5 to twice the speakers RMS power rating.

Randy

[autodidact]

I found this from another TB thread:

"Since the LH1000 has dual amps, you can run 2 x 4 ohms in dual parallel mode. That will give you a potential 640 watts and the ability to balance the output to the cabs. That is the way to go IMO"

Both cabs are 8ohms, does that help at all. Thaat thing I just quoted confused the hell outta me.

[Dark Barn]

If both speakers are 8 ohms then you should be able to run in bridged mono no problem. And you should see a small volume increase over running dual parallel.

From the LH1000 manual:

Originally Posted by Hartke LH1000 manual

If you are using two 8 ohm cabinets as a 4-ohm single load, switch the BRIDGE mode to BRIDGE and use a Speakon cable to connect your first cabinet, then use the cabinet's extension output to connect the second cabinet.

[BassmanPaul]

Originally Posted by Dark Barn

If both speakers are 8 ohms then you should be able to run in bridged mono no problem. And you should see a small volume increase over running dual parallel.:

A small increase in volume is the operative word. The amp is also going to be working harder than in parallel mode. I'd try parallel first. I've never felt the need to run in bridge. I've always received what I needed in parallel.

[autodidact]

Its loud enough in parallel, this was kind of just a "what if" thread. I may try bridge just to see if its worth it, chances are ill stick with parallel tho

[autodidact]

Originally Posted by Dark Barn

If both speakers are 8 ohms then you should be able to run in bridged mono no problem. And you should see a small volume increase over running dual parallel.

From the LH1000 manual:

So I should put a speakon from head into input 1 of my top cab and then use a regular cable from cab1 to cab2. Like a daisy chain deal?

[Jazzdogg]

I just looked at the manual:

The output is rated at 225 watts per channel into an 8 Ohm load, and 750 watts into an 8 Ohm load, bridged; a difference of 5dB, which would be noticable, but not startling.

Calculations @ 4 Ohms yield the same increase: 5dB

The dB scale is logarithmic; humans perceive an increase of 3dB as a subtle but noticeable increase; we perceive a 10dB increase as sounding "twice as loud." Doubling the volume requires ten times the amplifier power - IF the speakers can handle the increase. The power handling spec provided by most manufacturers of bass cabinets is so overstated as to be virtually meaningless.

To my ears, the 5dB increase in headroom that's available through bridging would be desirable if I were already playing at or near the maximum output of my amp; if I'm cruising at half power, I wouldn't bother.

If a significant increase in volume or girth is what you're after, adding speakers is a more effective method: if you start with one speaker and add a second, identical, speaker, you'll gain up to 6dB (3dB attributable to cabinet coupling, and 3dB from the increase in power/decrease in impedance) without turning up, or bridging, your amp.

[autodidact]

^ wow my brain hurts but I could actually understand that lol.

I'm using the amp at about 6 1/2 on the volume so I may just give it a shot just for the hell of it.

Thanks everyone

[EpiRipper]

Originally Posted by autodidact

So I should put a speakon from head into input 1 of my top cab and then use a regular cable from cab1 to cab2. Like a daisy chain deal?

Yes. I have an LH1000 as well and this is how I run mine into 2 x 400 watt cabs. When I first bought this amp I ran it in parallel mode and was unimpressed with the tone, it sounded nothing like it did in the shop. I switched to bridge mode and the reason I purchased this amp in the first place came back, loud and clear. Volume to make your head hurt and tone to die for.
Parallel mode, I felt, was lacking in the tone department in a big way. It sounded very thin and brittle, and lacked balls.
Bridge mode has a fuller sound and has balls bigger than King Kongs'.

BTW, if you are currently running your volume at 6 1/2 bridging the amp could cause your head and chest to implode. I've never had mine past 3 and am constantly being told to turn down.

[autodidact]

Originally Posted by EpiRipper

BTW, if you are currently running your volume at 6 1/2 bridging the amp could cause your head and chest to implode. I've never had mine past 3 and am constantly being told to turn down.

I'm playing like a grunge/alternative kind of deal so the bass needs to stick out and I'm playing with the loudest drummer I've ever met plus two guitarists that LOVE to crank their amps...then again...I get told to turn down too sometimes.

[BassmanPaul]

Originally Posted by autodidact

So I should put a speakon from head into input 1 of my top cab and then use a regular cable from cab1 to cab2. Like a daisy chain deal?

If your "regular" cable means a standard 1/4" phone cable they are not safe to use with an amp in bridge mode. Speakons are the only safe way.

[autodidact]

Originally Posted by BassmanPaul

If your "regular" cable means a standard 1/4" phone cable they are not safe to use with an amp in bridge mode. Speakons are the only safe way.

So I should just keep it in dual parallel? Because both my cabs only have 1/4" Jack inputs, not speakon. I know I can get a cable with one end Speakon and one end 1/4" is that dangerous?

[babebambi]

you can retro-fit those cabs with speakon receptacle

[BassmanPaul]

When your amp is in bridge both wires in the speaker cable are hot. Being 180 degrees apart these voltages add. With speakons it makes no difference. Phone plugs however are a different story. Both the tip AND the barrel of the plug are live. This presents a shock hazard for the user and the risk of blowing a channel of the amp if the metal of the plug touches any grounded object.

As Babebambi sugests, retro fit your cabinets for speakons.

[EpiRipper]

Just get the cable with the Speakon on one end and the 1/4" plug on the other. Your amp should be turned off when plugging your cabinets in anyway, so no chance of any shocks or damaging the amp. I've been doing it this way for a year now and have had no problem.

[BassmanPaul]

Originally Posted by EpiRipper

Just get the cable with the Speakon on one end and the 1/4" plug on the other. Your amp should be turned off when plugging your cabinets in anyway, so no chance of any shocks or damaging the amp. I've been doing it this way for a year now and have had no problem.

You forget that the metal of the phone plug is live in bridge. Something as simple a dropping your bass cable over your amp can cause a short. On stage most metal work such as light stands can be, and usually are, grounded. I reaffirm that what you are doing is potentially dangerous!

[autodidact]

Well thanks for all your help guys but it just seems easier to stick with dual parallel for now. But I'm keeping this sub'd for future reference tho