New Rack user question hooking up poweramp

[P I K A]

Yea I 've been an amp head user for years and now and downsizing to rack gear a simple preamp and poweramp and 2-12. Ok I got the genz benz 2-12 and the back has a mono 16 ohm input and under that 2 inputs labeled 8 ohm stereo left and mono right 8/4 ohms. Now the poweramp is the mesa 20 20 and I'm confused. It says use 1, 8 ohm cab in the 8 ohm jack of each channel, use 1, 4 ohm cab in 1, 4 ohm jack each channel ,use 1 , 16 ohm cab into the 8 ohm jack each channel.WTF I just want to plug and play so where do I plug this in? Also do I use it in stereo or mono. If mono am I using only 2 powertubes thereby only half the amp and then I can reverse the tubes after 12 months. Sorry guys for all the questions I just used to plug the 8 ohm head into the 8 ohm cab It was very easy. Thanks

[Outlander]

Re: New Rack user question hooking up poweramp

PIKA
for stereo use the 8 ohm outs of your amp into each input (left right) on the cab. you'll have even tube wear this way on both channels.For mono use one of the 4 ohm outputs on the amp to the 8/4 ohm mono input on the cab.Make sure you have nothing plugged into the unused channel and turn the volume and presence all the way off or down.Mesa recomends you alternate channels every so often or x amount of hours or so equally to provide equal tube wear on each channel if you use it this way.This way if you decide to run in stereo later on both channels will be equal in tone and power (theoretically!)
[img]graemlins/headbang.gif[/img]
I would just run it in stereo, then you don't have to keep switching the cables or keep track of operating hours per channel.On the other hand if you run in mono and gig you'll have a built in backup.

[ February 07, 2004, 08:18 PM: Message edited by: OUTLANDER ]

[Dreamland_Rebel]

Re: New Rack user question hooking up poweramp

ok plug 2 speaker cables into the 4ohm jacks of the mesa 20/20. run one into the left 8ohm stereo and the other into the right mono 8/4of the GB

~JW

[Outlander]

Re: New Rack user question hooking up poweramp

Let's not confuse him Dreamland....
you meant 8 ohm outs correct?

[Dreamland_Rebel]

Re: New Rack user question hooking up poweramp

no, his cab has 8 ohm stereo jacks, so when running 2 8ohm loads they creat a 4ohm drain on the amp.

cab reads 16 mono, 8 stereo left, and 8/4 mono right. which means it can run in mono 16, 8, or 4ohm; but uses 2 8ohm loads when run in stero.

so 4 and 4 on the mesa and 8 and 8 on the genz-benz.

~JW

edited to say that this is becuase the 20/20 is a stereo preamp.

[Dreamland_Rebel]

Re: New Rack user question hooking up poweramp

if you go to www.mesaboogie.com and veiw the manuel for the 20/20 (or any other amp for that matter) it explains how when using 2 cabs with one head (stereo or not) you use the speaker out that is rated for half the impedence of the cabs.

example: your head has one 16 ohm, one 8 ohm, and two 4 ohm speaker outs. you have 2 cabs both rated 8 ohms. when running both cabs you will want to plug both of them into the 4 ohm speaker outs. if only using 1 cab that is rated 8 ohms you will want to put it in the 8 ohm speaker out. if you have two 16 ohm cabs you will want to daisy chain them together and run them in the 8 ohm speaker out.

is this making any sense?

~JW

[P I K A]

Re: New Rack user question hooking up poweramp

[QUOTE]Originally posted by OUTLANDER:
[QB]
For mono use one of the 4 ohm outputs on the amp to the 8/4 ohm mono input on the cab.Make sure you have nothing plugged into the unused channel and turn the volume and presence all the way off or down.

Thanks I'll go with this arrangement as it seems fairly simple. Mesa says to turn the volume down but to crank the presence all the way up. I'll be in mono since I have only a 2-12 right now so mono is fine.Thanks for the replies I can now plug it in without any worries of frying the thing.

[yabba]

Re: New Rack user question hooking up poweramp

ok, apologies in advance for bumping an OOOOLLLLDDD thread, but I stumbled upon it with search and I'm feeling particularly dense today and just not getting this...

If a 2x12 cab (the g-flex discussed here, for example) is 8 ohms per side, then wouldn't you want to plug into the 8 ohm outputs on a stereo poweramp? (Directly from the 20/20 manual: "Use one 8 ohm cabinet in the 8 ohm jack of each channel"; isn't a 2x12 cab that runs 16 ohms mono/8 ohms stereo basically the same thing as say, 2 separate 1x12 cabs that run 8 ohms each?)

[Outlander]

Re: New Rack user question hooking up poweramp

Wow I was surprised to see this pop up.
Yabba you are correct.The G-Benz in stereo is 8 ohms. The 20/20 is a stereo amp.
I think Dreamland thought he wanted to hook up two 8 ohm cabs together thereby dividing the load which would be a 4 ohm load.
One of the things about the G-B is you can run it stereo 2- 8 ohm feeds or run it mono 1 -4 0hm feed.
I have the 20/20 and G-flex 2x12 and have run it stereo but would rather have 2 G-flex cabs and run one on each chanell (4 0hms)

[Newc]

Re: New Rack user question hooking up poweramp

This shit makes my head hurt. Gimme one cab, one power amp, and a mic (or a Mixer channel from the rack) into the PA if I need more volume [img]/images/graemlins/laugh.gif[/img]

[rodrigo_echeverri]

Re: New Rack user question hooking up poweramp

If I am ever in doubt I will just grab a tester and measure the impedance on the cab... once I am sure I have the right load I will hook it up to the power amp!...