Ohms, Impedence and Watts in Heads and Cabs

[ebe9]

I have seen numerous of threads in which people have been asking question with regards to matching the Wattage & Ohm/s of the head/amp to the Wattage & Ohm/s the cab and if they can run the two ratings differ.

The following are some articles/threads should hopefully help.

http://www.talkbass.com/forum/showthread.php?t=144244

http://www.talkbass.com/ampfaq/


Update: 28 February 2006

http://www.duncanamps.com/technical/technical.html (Impedence calculator for your cab and other information relating to amps/heads)

Update: 04 April 2006

http://sound.westhost.com/impedanc.htm
(Impedance and Audio Equipment)

http://www.maxim-ic.com/appnotes.cfm/appnote_number/742 (Impedance: The scientific explaination)

[muthafunkabass]

Cool articles. I wish you had posted them 3-4 months ago, not when i finally understand.

No problem, man...any resources and/or articles work great in here. Nice job.

-Gav

[Tryxx]

http://www.musicianforums.com/forums/showthread.php?t=329764

That should have some good links.

[tinnitus]

hey, thats pretty helpful, thanks alot,

Would i be able to use a GK 1001 RB (which is 700 Watts at 4 ohms, 480W at 8 ohms) with one 4 x 10 hartke VX Cab (Power handling: 400W at 8 ohms) for the time being, I wanna save up for a better cab later on...

[muthafunkabass]

Yeah, that would work.

[Trevo]

I am still veery confused
Could I hook up a [URL="http://www.musiciansfriend.com/product/Bass/Amps?sku=480695V"]Behringer B Stock BX3000T Ultrabass 300W Bass Head[/url] to a [URL="http://www.musiciansfriend.com/product?sku=486200"]Basson B15B 300W Bass Cabinet with 1x15 Speaker and Horn[/url]
Plz help me

[ebe9]

Originally Posted by goleafs_89

I am still veery confused
Could I hook up a [URL="http://www.musiciansfriend.com/product/Bass/Amps?sku=480695V"]Behringer B Stock BX3000T Ultrabass 300W Bass Head[/url] to a [URL="http://www.musiciansfriend.com/product?sku=486200"]Basson B15B 300W Bass Cabinet with 1x15 Speaker and Horn[/url]
Plz help me

Okay the cab you are looking at is running 300W at an impedence of 8 Ohms. The head is producing 300W at 4 Ohms.

The resistance (the impedence) of the cabinet is twice that of the head/amp, thus the head/amp will only be producing 150W at a rating of 8 Ohms.

What this basically means is that of the 300W availible to you by the cabinet, the head will only be supplying a potential 150W (just remeber that these are all guestimates as the exact number may differ slightly). I.e. You will be underpowering the cab by 150W or the cab has the ability to handle another 150W of power.

In short, Yes you can use those two items together, just do not turn the volume on the amp up too high as it will not be providing enough power to the cabinet and it may cause "clipping" of the speakers which is not very good for them.

[Trevo]

so I shoul hook it up to a cab that haas 600 Watts through 8 ohms
i think i undeerstand

[ebe9]

No...........you would just be making the problem worse then as the amp would still only be putting out 150W at 8 Ohms into a 600W Cab at 8 Ohms thus increasing the likelyhood of the speakers clipping.

In most cases it is the Amp/head that you need to invest the money in, in order to get one that has a decent wattage rating at various Ohm ratings.

E.g. A head/amp with a rating of 800W at 4 Ohms and a rating of 400W at 8 Ohms would be great.

What you must try and do is match the Ohm and Watt rating of the cabinet with a head of a similar rating.


EDIT: Read the links...............They explain it far better than what I can. That or email Edgebass if he has an address on his profile.

[muthafunkabass]

Dude, nothing needs a bump in the resource section.

[ebe9]

updated

[Trevo]

ebe9, would I be ok with a head with 180 watts at 8 ohms and a 150 watt cab at 8 ohms?

[Killer Fridge]

Yes, as long as you didnt push it right to the maximum.

[Pluperfect_Arson]

I just wanted to throw this link in here:

http://www.tunemybass.com/bass_amps/how_to_hook_up_heads_and_cabinets.html

It pretty much explains the same as the links in Ebe's post, but it is a bit easier to understand for those who don't quite have a grasp on the terminology.

[Polyamarous]

So a 575watt 4ohm head to a 500watt 4 ohm cab would be mmkay if I don't really push out the volume?

[ebe9]

Originally Posted by Polyamarous

So a 575watt 4ohm head to a 500watt 4 ohm cab would be mmkay if I don't really push out the volume?

Yes, that is actually ideal as he are pretty much matching.

And I do not know anyone who actually turns their gain and volume up all the way.


The thing to remember is that the rating the amp quotes is usually an RMS Wattage rating, i.e. the number of watts the amp can continuously push out with out doing any damage to itself.

Now unless you are actually running the amp at full you are not going to be using all of that power to the best of my knowledge.

[Polyamarous]

Who wants to shoot at what progam watss or something are?
Like you see an amp thats rated 300watts RMS and 700watts programmable or something.

[ebe9]

Originally Posted by Polyamarous

Who wants to shoot at what progam watss or something are?
Like you see an amp thats rated 300watts RMS and 700watts programmable or something.

Programme I think is just another name for Peak, but I am not sure.

[ludwig109]

if a cab is 800 watts at 8 ohm and the head is 700watts at 4ohm is the cab still couted as 800watts or is it halved?