Using 4 and 8 Ohm Together

[Buddhaful]

I have a Hartke 7000 HA Amp, a 1 x 15 Hartke XL Series with an Eminence Kappa 600W @8 Ohm speaker upgrade, and a 400W Ampeg 4x10HLF @ 4 Ohms.

Can I use these all together? What is the best configuration? I'm playing loud Hard Rock through the house PA. What change to the config if playing without a PA?

thanks.

[Zooberwerx]

Originally Posted by Buddhaful

I have a Hartke 7000 HA Amp, a 1 x 15 Hartke XL Series with an Eminence Kappa 600W @8 Ohm speaker upgrade, and a 400W Ampeg 4x10HLF @ 4 Ohms.

Can I use these all together? What is the best configuration? I'm playing loud Hard Rock through the house PA. What change to the config if playing without a PA?

thanks.

Yes, you may use them together, one per side with 240 watts and 350 watts respectively. Go full-range, do not bi-amp. Let your ears be the judge.

Riis

[madmatt]

Only if your amp can handle a 2 Ohm load.
Together they will appear as a 2.333 Ohm load to the amp.
If your amp cannot handle this it will burn up.

[Munjibunga]

Originally Posted by madmatt

Only if your amp can handle a 2 Ohm load.
Together they will appear as a 2.333 Ohm load to the amp.
If your amp cannot handle this it will burn up.

2.7 ohm load.

[walterw]

zoober's got it. that head has a stereo power amp, so one side per cab will work fine.

+1 to not biamping, you'll get more beef with both cabs run full-range.

[Buddhaful]

Thanks for the help. So no to biamping. How do I determine if it can handle the Ohm load? the specs show:

2 channel x 350W @ 4 Ohms
2 channel x 240W @ 8 Ohms

Does this mean it can't handle the load if I use both cabs?

Thanks again.

[Ric5]

Get a second head to run as a slave power amp and then you can run the extra cab very nicely.

Most amps cannot handle less than 4 ohms.

[Zooberwerx]

Originally Posted by Buddhaful

Thanks for the help. So no to biamping. How do I determine if it can handle the Ohm load? the specs show:

2 channel x 350W @ 4 Ohms
2 channel x 240W @ 8 Ohms

Does this mean it can't handle the load if I use both cabs?

Thanks again.

Here's the manual:

http://s3.amazonaws.com/samsontech/r...cs/ACF1903.pdf

The Hartke appears to have two independent power amps, one for each speaker. An impedence mis-match would be a critical issue if they were sharing a single amp source....which they are not. Keep the bi-amp switch in the "off" position. According to the block diagram, even with the bi-amp feature defeated, the balance control gives you some flexibility with the preamp feed to amps A & B. IOW, once your rig is up and running, you can tweak the balance between the 4 X 10 and 1 X 15 to get the tone you want.

Riis

[Buddhaful]

Thanks Zoober.

So because there are 2 amps it's not in parallel...therefore not 2.6 ohms?

So if my 4x10 is the 350Watt side and the 1x15 is the 240Watt side I could shift the balance toward the 1x15 side to 'even' things out?

I just want to make sure I shouldn't have the balance set more towards one side or the other to protect against any potential damage to the speakers or amp.

[Zooberwerx]

Originally Posted by Buddhaful

Thanks Zoober.

So because there are 2 amps it's not in parallel...therefore not 2.6 ohms?

So if my 4x10 is the 350Watt side and the 1x15 is the 240Watt side I could shift the balance toward the 1x15 side to 'even' things out?

I just want to make sure I shouldn't have the balance set more towards one side or the other to protect against any potential damage to the speakers or amp.

Exactly. As mentioned, the balance control appears to work independently of the bi-amp option but I could be missing something. I would give it a try with the balance centered and lower volume settings. I have a sneaking feeling the 4 X 10 will walk all over the 1 X 15. Anywho, experiment and give us a report. In essence, what you have is a 600 watt system which will look cooler than all git-out on stage....with a sound to match.

Riis

[walterw]

right, you have two independent power amps, so one will be running at 8Ω, the other 4Ω; no problem for either side.

just adjust the balance by ear so the two cabs are about the same volume. (or don't; the 4x10 will both get more power and be more efficient at the same power, so it should be a lot stronger than the 1x15 unless you back that side way down. frankly, this argues for leaving the 1x15 at home.)

[MikeCollatos]

I totally disagree with the people saying not to bi-amp this head. Unlike most heads this has a variable crossover and level control for each so you can blend them perfectly. I had this head for many years and loved the sound I got out of it bi-amping it. If it didn't have the variable crossover and balance feature I would agree go full range with both cabs but this head has it and you should at least play around with it. I think you will be very happy with the results.

[walterw]

all that does is take the low end out of one of the two cabs, cutting in half the available bass power.

biamping makes sense if you have, say, a 2x15 with a 2x10 sitting on top of it. otherwise, you're just emasculating one of the two cabs.

single 15s and especially 4x10s are meant to be run full-range.

[Zooberwerx]

Originally Posted by walterw

all that does is take the low end out of one of the two cabs, cutting in half the available bass power.

biamping makes sense if you have, say, a 2x15 with a 2x10 sitting on top of it. otherwise, you're just emasculating one of the two cabs.

single 15s and especially 4x10s are meant to be run full-range.

Bi-amping makes more sense when running a tweeter array which is not the situation. Hartke even suggests this in the manual. I believe the xover's high end freq. is 2.5 khz.

Riis

[Shadow123]

I'm actually looking to do the same thing with a Carvin r1000.
The manual shows 2 ohm power but in section 10. it mentions the amp will go into "protect" if loaded below 4 ohms. Is this ok to do?

http://www.carvinguitars.com/cartech...-seriesiii.pdf

[ggunn]

Originally Posted by walterw

all that does is take the low end out of one of the two cabs, cutting in half the available bass power.

biamping makes sense if you have, say, a 2x15 with a 2x10 sitting on top of it. otherwise, you're just emasculating one of the two cabs.

single 15s and especially 4x10s are meant to be run full-range.

Biamping not only takes the lows out of one cab, it takes the highs out of the other. Try it, you might like it. Some folks claim that biamping sounds clearer to them, even if both cabs are identical.

There is more to good sound than just volume.

[stingraysvt]

I would try and "trick" the sound guys, I'd use my bi amped setup to turn down my highs and leave the lows up enough I could feel it.

I guess it worked ok I only tried it once or twice.

Coming from a sound guy, we can hear when you are too loud, so don't try it! Lol!

[Buddhaful]

Good thing I went early in the day for a line check. I initially set up full-range. Sounded loud, very loud. As I warmed up I noticed some strange sounds coming from both cabs. At times the 15 kinda fluttered if I just barely hit the E string. I messed with the balance knob a bit, and was at the point where I was just going to play out of the 4x10 due to fears of blowing the 15. Even the 4x10 didn't sound as good as I was used to.

I thought about MikeCollatos input and the fact he owned the same head and decided to try it bi-amped really quick. I set the crossover at 250 Hz (250 to 20 Hz to low frequency speaker jack; 250 and higher to high frequency speaker jack). I had the 15 hooked to low and 4x10 hooked to high.....HALLE-F'in-LUJAH!

Crisp, clear bass tone (especially with a SansAmp RBI), Loud as you know what. "Very happy with the results".

Thanks to everyone for their input. I get to do it all over again Saturday.

[Zooberwerx]

Originally Posted by Buddhaful

Good thing I went early in the day for a line check. I initially set up full-range. Sounded loud, very loud. As I warmed up I noticed some strange sounds coming from both cabs. At times the 15 kinda fluttered if I just barely hit the E string. I messed with the balance knob a bit, and was at the point where I was just going to play out of the 4x10 due to fears of blowing the 15. Even the 4x10 didn't sound as good as I was used to.

I thought about MikeCollatos input and the fact he owned the same head and decided to try it bi-amped really quick. I set the crossover at 250 Hz (250 to 20 Hz to low frequency speaker jack; 250 and higher to high frequency speaker jack). I had the 15 hooked to low and 4x10 hooked to high.....HALLE-F'in-LUJAH!

Crisp, clear bass tone (especially with a SansAmp RBI), Loud as you know what. "Very happy with the results".

Thanks to everyone for their input. I get to do it all over again Saturday.

Glad it worked our for you! I'm a bit curious about the quirks highlighted above to the point where I'd re-assemble the rig in a controlled environment (read: my living room) to determine the "how's" and "why's". From your description, things sounded really bad in full-range operation and may be a bone of contention should you ever need to run a single cab (maybe the 4 X 10?) in the future.

Riis

[Buddhaful]

I posed the same question to Hartke and here was their response:

The 7000 is a stereo amplifier. You can safely connect one 4 ohm cabinet (to the “High” side output) and the other 8 ohm cabinet to the “Low” side output. With your configuration bi-amp would be the ideal setting as it will allow you to set the crossover frequency and balance between the 410 and 115. The full range option is for cabinet configurations that have the same diameter speaker (meaning multiple 410 cabinets, or multiple 115 cabinets, etc).

Riis, I replied to Hartke and mentioned the issues when set up in full-range. If they respond I'll post it here. Prior to this setup I had always used my 4x10 with no problems. I'm hoping the quirk when I had the balance all the way to one side for the 4x10 was due to the fact I still had the 1x15 hooked up even though I wasn't 'using' it.