• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join freeLog in
    Want zero display ads or expanded classifieds tools? Compare plans.

Ohms FAQ

I read the whole first post and the first and last pages here. So, if I am getting an amp, the lower the rating would be better for flexibility - is that right? Because you could add cabinets, lower the load and then still be at or above the rating of the amp - am I understanding correctly?

If the above is true, then buying a 4 ohm amp with a 4 ohm cab would not be a good idea if you want to expand in the future. It would be better to buy a 4 ohm amp and an 8 ohm cab - but then wouldn't you be cutting the wattage in half?
 
What are you trying to accomplish by setting the switch to a different impedance than the cab you are driving? There isn’t untapped power available by doing this. To the contrary, there is less. Plus, running a higher load impedance on a tube amp than the transformer tap can over-voltage the output tubes causing damage.
 
So if I wanted to get an overdriven sound from my amp could I run my head at 2 ohms into a 4ohm cab? and then just crank it as the cab would be getting half the wattage? Does that make sense or would I kill my amp?

Frankly, it does not make sense..............


Just how do you propose running your amp at 2 ohms into a 4 ohm cab ?

If it is a tube amp, you can blow the amp using an impedance mismatch.

If your amp is solid state, there is no "ohm selector" switch. If you hook up a 4 ohm cab, your head will run at 4 ohms.

Also, a S/S amp running at 2 ohms puts out MORE wattage then when running at 4 ohms - so your "theory" of the cab getting 1/2 the wattage is incorrect.
 
Absolutely NOT. Never plug two amp outputs into the same cabinet. You'll fry one or both of the power amps.

Just wanted to say i have hooked up 2 power amps to 1 speaker, or more specifically the left and right positive leads from a stereo pwr amp(did nothing with the negatives). I did it with an old Macintosh tube amp and also a Cmos type amp i cant remember the brand of. I doubt you could do this with some amps. And 2 totally separate amps ^^shrug^^ Ill let ya know when im willing to sacrifice a couple.
However all mids and lows were washed out leaving only highs that sounded tin cany , But there was some cool echo effects going on with this. Made me wonder if thats how they achieve surround sound in some systems.

My thoughts on hooking 2 amps to one cabinent for bass would only work if there were multiple speakers ,and you just add the wireing so they are essentially 2 separate speakers. Although probably not gona be optimal , but might work decent with the right speakers. The other option would be a dual voice coil speaker. But how many times do you run across one of those specifically for instrument bass?

Ive spent alot of time hooking up different speaker combonations , Blown my share of amps and speakers too. I suggest if your interested in experimenting , invest in a multi meter or ohm meter atleast. Its kinda fun hooking up a wall of cheapy speakers through multiple series/paralell sets.

And I'd like to add that i thought I had a pretty good grasp of what I needed to know when shopping speakers. Come to find out that db sensitivity rateing is kinda important and not just one of those worthless #'s to leave for the sound guy techies :eek:

Thanx for a great post Mike
 
This is my first post so I cant wait to hear the knowledge and experience that is out there. here is my delima:

I have an Ampeg SVT 4 Pro (Hybrid) and an Eden 4X10xlt 4ohm cab(RMS 700 watts)

I would like to add another 4X10 Eden cabinet to my Ampeg SVT 4 Pro. Should I get an 8 or 4 ohm cabinet? In other words...What is the "best" output scenario for this set up?

Historically, I have run the Ampeg svt 4 with a 6x10classic but I am not happy with it and I am looking to do something with my Eden cab instead. I also have an Eden traveler WT-300 I could throw in the mix, but I am almost positive this amp can only handle a 4ohm load. Thanks for reading the post. I am looking forward to the feedback the.
 
This is my first post so I cant wait to hear the knowledge and experience that is out there. here is my delima:

I have an Ampeg SVT 4 Pro (Hybrid) and an Eden 4X10xlt 4ohm cab(RMS 700 watts)

I would like to add another 4X10 Eden cabinet to my Ampeg SVT 4 Pro. Should I get an 8 or 4 ohm cabinet? In other words...What is the "best" output scenario for this set up?

Historically, I have run the Ampeg svt 4 with a 6x10classic but I am not happy with it and I am looking to do something with my Eden cab instead. I also have an Eden traveler WT-300 I could throw in the mix, but I am almost positive this amp can only handle a 4ohm load. Thanks for reading the post. I am looking forward to the feedback the.

AFAIK that amp (the SVT 4-Pro) will run at 2 ohms, so your ideal setup would be another identical copy of your 410 XLT.
 
Have I got the whole watts/ohms thing figured out? If you have a 4x10 cab rated at 800 watts@8ohm each speaker would be rated at 200watts (200 watts x 4 =800 watts) and if the head puts out 400w@8ohms that 400 watts is equaly split between each speaker & each recieve's 100 watts, only half of its limit
 
Correct me if I'm wrong here...

I'm looking at the manual for a stereo power amp and it says this:

Dual mode (both channels driven):
305 watts into 4 ohms.
175 watts into 8 ohms.
100 watts into 16 ohms.
Bridge-Mono mode:
610 watts into 8 ohms.
355 watts into 16 ohms.

So if I'm running it bridged, does this mean that I shouldn't run my cabinets parallel, because the impedance would only be 4 ohms?
If doing this can I assume that the wattage would just be 305 @ 4 ohms, which is split between the cabs making for 152.5 watts per cabinet?

So would it be better to hook up one cab to each side and get 175 watts to each?

So if one of my channels fails I could hook it up to one side parallel and only suffer a loss of ~25 watts each?