To bridge or not to bridge?

[Dace]

What is better stereo or bridged?
2XT48 30" with Lab15s
XTI2000

[Bill Fitzmaurice]

Never bridge.

[Gregory East]

Aye aye aye, I need to limit two T48 3015LF on a single XTI2000 channel to be safe.

[mr.lussier]

Never bridge.

Damn, I use my amp bridged....

Why is that one must not bridge ?

[Dan30]

One high voltage spike and *poof* goes your driver.

[mr.lussier]

Ok, but why voltage spikes are more dangerous on a bridged amp ?
And if you run a properly set-up limiter ?

[BrentEvans]

Ok, but why voltage spikes are more dangerous on a bridged amp ?
And if you run a properly set-up limiter ?

They're not. What is more dangerous is that the bridged amp can generate much more voltage, and doing so is usually not necessary.

Bridging is only warranted when the single channels of the amp being bridged cannot produce sufficient voltage to perform the requried task (for instance, bridging two amps capable of 35v to push a speaker that can handle 60). You still must limit, but what is the point of roughly doubling voltage output just to limit it back by half or more?

[Bruce Weldy]

I power two 3012LFs with a bridged Crown XLS1500. It's not powerful enough to run it in stereo mode.

Tried my Crown xTi 2000 - but it just didn't have enough headroom, so went back to the bridged 1500......been running that way just fine for two years.

Personally, I think it's a good option to be able to buy an amp (XLS1500) that will bridge at 1100 watts/4 ohms (66 volts) for half the price of an amp (xTi 2000) that pushes 400 watts @ 8ohms/channel (56 volts).

Limiting to 56 volts let me run clean with a little headroom on the bridged amp.

[BrentEvans]

Tried my Crown xTi 2000 - but it just didn't have enough headroom, so went back to the bridged 1500......been running that way just fine for two years.

IME the 2000s would be just barely enough... headroom is moot when limiting. What was the voltage you were getting out of your 2000?

[Bruce Weldy]

Tried my Crown xTi 2000 - but it just didn't have enough headroom, so went back to the bridged 1500......been running that way just fine for two years.

IME the 2000s would be just barely enough... headroom is moot when limiting. What was the voltage you were getting out of your 2000?

I was getting right at the 56 volts, but it was clipping way too often at lower voltages - pretty much every kick drum hit. Switched to the bridged XLS with the same set up and same limit and wasn't clipping.

I like having a little extra. I put the 2000 on monitors and all is well.....except of course, for that dang hissing from the 2000 - seems to be kinda' normal for those from what I've read.

[DJ Terrabass]

Hi everyone, I was looking for an appropriate thread to post this and think here should be fine so here goes....

I have some findings from the Xti2000 amp from tests done earlier today. Using a QM-1500 multimeter without speakers attached to measure peak voltages for each limiter setting provided in the onboard-DSP I found that.....

(EDITED STATS with +20dB EQ)
Peak voltage without limiter on was normally 60-65 volts up to 77 volts peak
Limiter set to -3dB was normally 40-45 volts up to 61 volts peak
Limiter set to -6dB was normally 27-32 volts up to 46 volts peak
Limiter set to -12dB was normally 14-17 volts up to 33volts peak

The tests were done with mixer gain prior to the amplifier to make the signal about as hot as a line-level signal would ever get. The model of multimeter used could have been better but it should be fine for the purposes in the experiment.

Hopefully some will find this useful if using the Xti2000/T48 w.3015lf combo for subs
Cheers

[doncolga]

Previously, I'd have never dreamed that I would not run my sub amp bridged, but I'm running my four T30's off a little EPQ 1200 in dual mode and it gives me just enough swing to just engage the limiter on full tilt.

[Gregory East]

Hi everyone, I was looking for an appropriate thread to post this and think here should be fine so here goes....

I have some findings from the Xti2000 amp from tests done earlier today. Using a QM-1500 multimeter without speakers attached to measure peak voltages for each limiter setting provided in the onboard-DSP I found that.....

Peak voltage without limiter on was normally 60-65 volts up to 75 volts peak
Limiter set to -3dB was normally 40-45 volts up to 53 volts peak
Limiter set to -6dB was normally 30 volts up to 39 volts peak
Limiter set to -12dB was normally 15-16.5 volts up to 21volts peak

The tests were done with mixer gain prior to the amplifier to make the signal about as hot as a line-level signal would ever get. The model of multimeter used could have been better but it should be fine for the purposes in the experiment.

Hopefully some will find this useful if using the Xti2000/T48 w.3015lf combo for subs
Cheers

This tallies with my rougher and readier testing with a basic meter and overdriven sinewaves. There has been at least one instance of 3015lf being torn up with a 3dB limited xti2000 however.

[DJ Terrabass]

This tallies with my rougher and readier testing with a basic meter and overdriven sinewaves. There has been at least one instance of 3015lf being torn up with a 3dB limited xti2000 however.

Yeah it was from reading one of those posts about the 3015lf being torn on another thread which led me to do some testing of the amp to start with. Maybe it was from improper high-passing of the sub? But I'll stick to my -3dB limit and 48dB/oct L-R high-pass @35Hz and report back if the driver breaks before it's time . Seems like building more cabinets outweighs trying to get the most out of each driver substantially

[Tom Smit]

Seems like building more cabinets outweighs trying to get the most out of each driver substantially

+1 that's what Bill has been suggesting for yeeaaaarrrsss.

Edited to correct the author of the quote.