Yet another wattage/Ohms question

capnjim · #1 03-26-2010, 11:24 AM

I can't find any answers to my question from a search and its not something I can try as I need help deciding which cab to use.
I have two really nice 70's 15" speakers which I got completely rebuilt at 4 ohms each. I was going to put them in my 2x15" cab to make a 400 watt 8 ohm cab.
I have since come across a great deal on a GK 400RB III. The amp is 240 watts at 4 ohms or 160 at 8.
Here's the question:
Will I get more volume using an 8 ohm 2x15" cab at 160 watts, or I was thinking of buying a cab (There's one for sale locally with a blown speaker for 100$) and putting in one of my "new" 4 ohm speakers. I can then use the full 240 watts with one 15" cab and have a spare speaker.
I know I could use the 2x15" and get another 8 ohm cab, but I want to stick with what I have.
The guy who re-did my speakers said they where some of the best made in the seventies and can easily handle 200-250 watts each.
Whaddya think will give me the most useable volume?
Thanks

Bass_Pounder · #2 03-26-2010, 12:06 PM

Pushing a single speaker with higher wattage than a pair of matched drivers at a lower wattage will not result in more output.

The difference in wattage from 160 to 240 watts is negligable.

Besides - just because the wattage rating of the single driver seems to match up, you will be displacement limited to around 100 - 150 watts before the speaker starts to fart out on lower frequencies.

Go with the 2X15.

lomo · #3 03-26-2010, 12:43 PM

Pairing 2 4 Ohm 15s will give you 2 Ohms impedance, not 8.

**Thor** · #4 03-26-2010, 12:46 PM

Only if wired in parallel. If he wires then in series they will
be an 8 ohm load.

capnjim · #5 03-26-2010, 12:58 PM

yeah..I was going to wire them to 8 ohm so I have a 400-500 watt cab.
So, will this rig, the GK 400RB and my 2x15" at 8 ohms be loud enough for a band with a medium hitting drummer and two reasonably loud guitars?
I haven't bought the GK yet, but I really miss my 1001RB and am not crazy about the sound of my new Trace Elliot 715x.
I would love an 800rb but can't afford it.
The 1001rb was way too much amp and I never pushed it past 10:00 on the master.
Thanks for the help.
I'm only asking because I have this cab already, and i can buy the 400 III locally for 175$ which is about the limit for my budget. If it will get me back to the sound i had with the 1001 a few years ago i would be very happy to be spending only 175$.

capnjim · #6 03-26-2010, 01:00 PM

BTW Lomo..love your Avatar. My hero as a kid. I still have his rookie card.

lomo · #7 03-26-2010, 01:05 PM

Quote:

Originally Posted by capnjim

BTW Lomo..love your Avatar. My hero as a kid. I still have his rookie card.

Thanks. I'm a sucker for an outstanding athlete with a mind to match and class to boot. We have too many athletes who are intellectual and moral slouches (to say the least) setting bad examples IMO. Sorry for misleading you-I never though about the parallel wiring option.

capnjim · #8 03-26-2010, 04:56 PM

Nobody's familiar with the 400RB III?
I trust you guys way more than the dumb reviews on HC.

M0ses · #9 03-26-2010, 04:58 PM

I'd say yes. Definitely. I don't believe the people who say you need 300W to gig, because I gig with 200W and a 1x15, and I never go past half volume and gain.

Bass_Pounder · #10 03-26-2010, 05:05 PM

Quote:

Originally Posted by M0ses

I'd say yes. Definitely. I don't believe the people who say you need 300W to gig, because I gig with 200W and a 1x15, and I never go past half volume and gain.

What works for does not work for everyone.

I for one would not want to put 160 watts up against 2 guitars and drums.

The OP states he had a 1001RB was "too much amp" because he never drove it past 10 o'clock.

I am from the camp that believes if you have to run your amp past noon, you need a bigger amp.

**Thor** · #11 03-26-2010, 05:43 PM

Quote:

Originally Posted by capnjim

yeah..I was going to wire them to 8 ohm so I have a 400-500 watt cab.
So, will this rig, the GK 400RB and my 2x15" at 8 ohms be loud enough for a band with a medium hitting drummer and two reasonably loud guitars?
I haven't bought the GK yet, but I really miss my 1001RB and am not crazy about the sound of my new Trace Elliot 715x.
I would love an 800rb but can't afford it.
The 1001rb was way too much amp and I never pushed it past 10:00 on the master.
Thanks for the help.
I'm only asking because I have this cab already, and i can buy the 400 III locally for 175$ which is about the limit for my budget. If it will get me back to the sound i had with the 1001 a few years ago i would be very happy to be spending only 175$.

I'd say go for it. The head is a good deal, the rig isn't costing
you much.

What brand were the drivers? JBL's. Altecs. Emininence? Any idea?
If you could nail that down we could model the response
if we can get an idea of the TS parameters. Kind of a long
shot but worth pursuing. Alternately, you could probably
model the cab for a set of Em Delta LF 15's for pretty
cheap later and have a REALLY KICK@$$ rig. Raawr!

capnjim · #12 03-26-2010, 10:56 PM

Thanks for the reply Thor..I don't know the brand of drivers. My speaker guy, who has been re-coning forever, says they are generic 70's speakers that were used in Klipsch and other high end speakers. He said they were probably, in his opinion, the best ever speaker made for bass. Giant square magnets.

johnk_10 · #13 03-26-2010, 11:46 PM

big square magnets sounds like either old CTS or Eminence 15's to me. and if they are, your speaker tech is living in the past. IME, they weren't even very good back then. IMO, bass speakers have made some very large improvements since the 70's. (although i am still a big fan of JBL K140's and still use them).