Do these exist?

[Davebass]

I've had an idea, I'm hoping this is a known idea and already exists!

Do Amp Attenuators exist? for example taking the out put of a bass head into a 4 ohm dummy load/attenuator then into a 4 ohm cab giving a total of 8ohm impedance? Obviously this could be very beneficial for running a 4ohm min head into 2 4ohm cabs?

Any thoughts?

[Phendyr_Loon]

I know dummy loads are available for the purpose of home audio amplifier repair/testing. Those may not be suitable due to higher power ratings associated with bass amplification. I would think you'd have to look into DIY for that sort of thing, I don't know all the "ins and outs" of loads and circuitry but for starters you'd probably have to fabricate a casing with a pretty sizable heatsink.

[greenboy]

What are you after here? I'm getting a mixed message.

[father of fires]

Glockenklang 600 Impedance Transformer

[Davebass]

To put it into a simpler context:

Amp Head 500w @ 4ohm -> 4ohm cab 300w .... putting too much power to cab. Not really a problem but it also means you can add another cab if needed ....

so if you have a dummy load in series you could do this:

Amp Head 300w @ 8ohm - > 4 ohm dummy load -> 4ohm cab 300w. If we have this dummy load then we can be safe in the knowledge that the cab isnt being overpower. It also means we can add another 8ohm cab to get to the full 500 watts again.

does this make sense or is this impossible?

Cheers,
Dave

[JTE]

So, you'll get the full power out of the amp, but most of that energy goes into heat at the dummy load instead into moving air.

John

[Handyman]

Originally Posted by JTE

So, you'll get the full power out of the amp, but most of that energy goes into heat at the dummy load instead into moving air.

John

Exactly. This is like trying to get more power out of your car by dragging concrete blocks behind it. Yes, your engine will be doing more work, but it will be entirely useless work.

[Bass_Pounder]

Originally Posted by Davebass

To put it into a simpler context:

Amp Head 500w @ 4ohm -> 4ohm cab 300w .... putting too much power to cab. Not really a problem but it also means you can add another cab if needed ....

so if you have a dummy load in series you could do this:

Amp Head 300w @ 8ohm - > 4 ohm dummy load -> 4ohm cab 300w. If we have this dummy load then we can be safe in the knowledge that the cab isnt being overpower. It also means we can add another 8ohm cab to get to the full 500 watts again.

does this make sense or is this impossible?

Cheers,
Dave

OK, so let me get this straight.................


You think it is a good solid idea to go from:

500w amp powering a 300w cab, and using judgement to guide volume level

To:

300w amp powering a 300w cab + a dummy load so that there is only a MAX of 150w available for the cab, and another 150w being burned off as wasted energy ?

[Davebass]

But would connecting a second 8ohm cab in parallel not bring the load back to 4ohms and then regaining max power?

[Handyman]

Originally Posted by Davebass

But would connecting a second 8ohm cab in parallel not bring the load back to 4ohms and then regaining max power?

Yes, but 50% of the power your amp is putting out would be turned directly into heat by your load resistors. If your resistors were replaced with 4 ohm speakers, you would have something useful going on.

[Downunderwonder]

Yes, still wasting a lot of power. If you really want to make the most of the amp then lose the 4 ohm cab and get two 8 ohm that will handle it.

The attenuators for bass I've seen are pretty pricey so matched cabs is definitely the way to go.

[Bass_Pounder]

Originally Posted by Davebass

But would connecting a second 8ohm cab in parallel not bring the load back to 4ohms and then regaining max power?

No it would not..............

You would still be sending power to the dummy load

[Davebass]

Yeah thats fair enough, it makes sense.

Was just an idea to get more out of what I've got. Switching to a 8ohm cab is pretty much out the question with my current finances.

Wish it was as simple as attaching a 4ohm resistor to a speakon!

[greenboy]

Originally Posted by Davebass

Was just an idea to get more out of what I've got.

What - more HEAT? Or more AUDIO?

[chokeslam512]

Originally Posted by Davebass

I've had an idea, I'm hoping this is a known idea and already exists!

Do Amp Attenuators exist? for example taking the out put of a bass head into a 4 ohm dummy load/attenuator then into a 4 ohm cab giving a total of 8ohm impedance? Obviously this could be very beneficial for running a 4ohm min head into 2 4ohm cabs?

Any thoughts?

a 4 ohm dummy load and a 4 ohm cab will give you a total impedance of 2 ohms, not 8. If you are wanting to get the max out of your head (running at total wattage), you have two choices. First: run one 4 ohm cab, if the cab is rated at a lower power handling than your amp is putting out, turn the volume down. Choice two: run two 8 ohm cabs @300W each, that will reduce the risk of exceeding the power handling of the cabs.

[greenboy]

Originally Posted by chokeslam512

that will ensure that your will not exceed the power handling of the cabs.

There is no assurance. Most cab manufacturers don't state anything that you can take to the bank about excursion limits. Good thing too - the numbers they would have to sway the customer with would be decidedly unimpressive.

[Arjank]

Just for jokin' and not to answer the OP question.

This made me suddenly think of guys saying "I have these blah blah speakers and they are 1000watts, so they are better then yours"
I allways tell them wattage has nothing to do with qaulity or loudness. I could easily build a 10000watts speaker just by adding some resistors or an heating element to suckup the power and dissapate it into heat Yeah, that would be a very sucky speaker system. Those speaker eat current for breakfast man!

Just jokin'

[seamonkey]

Originally Posted by Davebass

To put it into a simpler context:

Amp Head 500w @ 4ohm -> 4ohm cab 300w .... putting too much power to cab. Not really a problem but it also means you can add another cab if needed ....

so if you have a dummy load in series you could do this:

Amp Head 300w @ 8ohm - > 4 ohm dummy load -> 4ohm cab 300w. If we have this dummy load then we can be safe in the knowledge that the cab isnt being overpower. It also means we can add another 8ohm cab to get to the full 500 watts again.

does this make sense or is this impossible?

Cheers,
Dave

You also need to look at the impedance curve of the speaker in the cabinet. Resistance is constant for resistor dummy loads, but driver impedance swings up and down.

If you look at Eminence.com they have a load of reference designs. The 4 ohm rating is around the mid freq of the driver. In the bass frequencies it rises, or may rise and fall and rise. depending if the cabinet is ported.

Putting in a series load changes the frequency response of the cabinet to begin to match the impedance. The low frequencies are those that are likely to damage the speaker may not attenuate much, so it may not help much.

It's smarter to change the frequency response using EQ than series resistors. Turn the volume down, but turn the bass down also.

[chokeslam512]

Originally Posted by greenboy

There is no assurance. Most cab manufacturers don't state anything that you can take to the bank about excursion limits. Good thing too - the numbers they would have to sway the customer with would be decidedly unimpressive.

Good catch. My post has been adjusted accordingly. Imma go ahead and get back to the effects forum where I belong.

[greenboy]

Ah, don't do that. Just sayin' it always comes down to the player using their ears, common sense and getting educated.