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Crate Power Block : should "bridged mono" be louder?

topo morto

Member
Messages
1,574
Simple, and possibly idiotic, question.

I have my cab plugged in the mono output of the Crate. I'm just plugged into the instrument input on the front.

should it be louder with the "bridged mono" button pushed in? Or does that just give it more juice before the protection kicks in?

It's the first amp I've had with a bridged mono mode, so bear that in mind!

Thanks.
 

Silent Sound

Member
Messages
5,520
Bridged mono should only be used when you're hooking the amp up in a bridged mono configuration. Look it up in the instruction manual for more information on how to do this. Each amp will have different requirements, so you really need to know the specifics of that particular amp before using it.

Generally, if an amp has a bridged mono capability, it will usually produce more power in that configuration. But you have to hook up the speaker correctly for it to work, so you don't blow the amp. Bridged mono will usually have different impedance and hookup requirements than the amp would in more typical configurations. So often to get the extra power from a bridged mono setting, you'd have to use a different speaker, and wire it up differently than you ordinarily would, to match the impedance difference.

My advice to you would be to ignore the bridged mono option and just use it as a normal amp. Keep the bridged mono turned off. Then maybe do a bit of research on that option for future reference should you ever need to use it on that amp, or on a different amp. It's typically only a feature found on P.A. oriented solid state amps, and rarely applies to guitar, bass, or keyboard amps. The most common reason to use a bridged mono configuration is to power a subwoofer.
 

phonix

Member
Messages
35
Notwithstanding the above, which is good advice to to make sure you've configured it as per requirements - you need about 10 times more power to have something sound twice as loud. Unless bridged mono adds a substantial amount more power, you're unlikely to really clearly hear the difference. It'll really just give you some more headroom before the onset of clipping.
 

drbob1

Gold Supporting Member
Messages
29,037
On the Powerblock, it's not very tolerant of impedance mismatching, so, use bridged mono if you have a single speaker at the correct impedance. For a pair of speakers, or a single speaker at the higher, mono impedance use the "stereo" output.
 

IM4Tone

Member
Messages
3,769
All these comments....have you ever seen a Crate Power Block up close?
Speaking as an owner, there are three speaker jacks in the rear: Mono (8 ohms/150 watts), Left (4 ohms/75 watts) and Right (4 ohms/75 watts). The button that is labeled 'Bridge/Mono" is meant to be pressed when using the single Mono speaker jack alone. When driving two 4 ohm cabs, the button is not depressed and the cabs plug into the Left and Right Jack. It's that simple!

(in both cases, the ohm rating is minimum, which is important for SS)
 

topo morto

Member
Messages
1,574
All these comments....have you ever seen a Crate Power Block up close?
Speaking as an owner, there are three speaker jacks in the rear: Mono (8 ohms/150 watts), Left (4 ohms/75 watts) and Right (4 ohms/75 watts). The button that is labeled 'Bridge/Mono" is meant to be pressed when using the single Mono speaker jack alone. When driving two 4 ohm cabs, the button is not depressed and the cabs plug into the Left and Right Jack. It's that simple!

(in both cases, the ohm rating is minimum, which is important for SS)
My question is because the manual says " The Mono output is to be used when the Bridge Mono switch (#10) is depressed" - but it is still operational when the switch is not depressed. However, switching it in and out doesn't seem to change the volume at all really - is this the same for you? Maybe (as phonix says) it's what I should expect.
 

The Kid

Member
Messages
5,423
All these comments....have you ever seen a Crate Power Block up close?
Speaking as an owner, there are three speaker jacks in the rear: Mono (8 ohms/150 watts), Left (4 ohms/75 watts) and Right (4 ohms/75 watts). The button that is labeled 'Bridge/Mono" is meant to be pressed when using the single Mono speaker jack alone. When driving two 4 ohm cabs, the button is not depressed and the cabs plug into the Left and Right Jack. It's that simple!

(in both cases, the ohm rating is minimum, which is important for SS)
Good to know.
 

IM4Tone

Member
Messages
3,769
My question is because the manual says " The Mono output is to be used when the Bridge Mono switch (#10) is depressed" - but it is still operational when the switch is not depressed. However, switching it in and out doesn't seem to change the volume at all really - is this the same for you? Maybe (as phonix says) it's what I should expect.
I just follow the directions because it's solid state, not tube. A single cab 8 ohm (or more) plugged into Mono w/ the switch depressed makes available the maximum safe volume. You want less....turn the vol. &/or gain knobs down. We're not dealing with preamp nor power tube distortion here.

So, what is the point of the question? If it's purely curiosity, you need a schematic to see how the speaker jacks are wired and the bridge switch...i.e. parallel, series, with resistance added, etc.

If you just want to know how to safely operate the amp, follow the directions.
 

topo morto

Member
Messages
1,574
So, what is the point of the question?
I just got it off ebay and want to know if it's working properly.

With the instrument plugged into the front panel input, and an 8 ohm cab plugged into the mono output, I was wondering why I don't get a perceptible volume boost when pushing 'bridged mono'.
 

Bobby1Note

Member
Messages
34
I just got it off ebay and want to know if it's working properly.

With the instrument plugged into the front panel input, and an 8 ohm cab plugged into the mono output, I was wondering why I don't get a perceptible volume boost when pushing 'bridged mono'.
A "doubling" of power, will only yield a barely perceptible 3dB increase,,,, at best,,,,,,

If the loudspeaker is in "power-compression", you'd get even less,,,, say, 1-2db more per doubling of power. Added power to the speaker,,, means added voice-coil temperature, over-excursion,,,, and the premature release of the "magic smoke".
 

topo morto

Member
Messages
1,574
The volume does not change. There's certainly no 3dB increase. this is with things all very quiet and low power - very much doubt any limits are being hit.
 

louiscyfer

Member
Messages
99
The volume does not change. There's certainly no 3dB increase. this is with things all very quiet and low power - very much doubt any limits are being hit.
3dB increase is difficult to hear. there would be no increase in volume at the same volume setting, the only time you would notice it when you push it to maximum capacity. you'll have more headroom, so it will be louder before going into clipping. that is the only place you'd notice.
 

topo morto

Member
Messages
1,574
3dB increase is difficult to hear.
I know 3dB's only a small difference, but if there actually was a 3dB difference between the modes (at the same volume setting) I'd have thought it'd be enough to hear when actually switching the button in and out. I can't hear any difference - I was just wondering if this was the same for other owners.

there would be no increase in volume at the same volume setting.
Well if that's the answer, that's the answer! thanks.
 






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