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Amp Rig Ohms Puzzle...

KevInDaBassment

KevInDaBassment

The cat's "meh..."
Jul 30, 2010
8,461
9,358
Gulf Coast
#1
EDIT: Buying a Palmer merging box to take two 4-ohm cabs to 8-ohms and call it a day.


Ok so here's the situation in brief...

The band I'm in has flopped back and forth on what style we are going for, related to whether there is a lead guitarist or not. We are now a three piece and have decided to keep it that way. When we had a lead guy before, the BL wanted a Strokes kind of tone from me. So big, clean, and thumpy was the goal there. Back to a 3-piece, he wants something more like Scott Pilgrim and Cliff Burton, which to him means fuzz and various kinds of dirt on bass. Here's where amps come in:

My "fuzz n' effects rig" is a GK MB200 into an Avatar 2x10 Neo. My Strokes-style rig is a Traynor YBA200-2 and Kasino 2x15's with Eminence Legends inside. I like the flexibility of the GK MB200 for all the effects (chorus, fuzz/OD/dist, pitch shift, envelope filter, etc) because of the active 4-band EQ. The subtleties I pick up in my tube amp kind of get lost when I pump that many effects into it, not to mention the 2x15s cab is quite the haul (easily over 100lbs). The all-tube and 2x15 rig is fantastic with that sweet spot, but I like it for mild grit and mostly that warm thump, so I'm keeping that rig but not roading it if this is the direction we're going.

Now the only problem is the neo 2x10s is a 4 ohm cab, which is fine for rehearsal, but I'd like to do a two 2x10 line array for practice/shows so I can hear myself better. Honestly the tonal response of the cab is very good, I don't drop tune my p-bass or anything so I'd just like more volume and something closer to my ears. I LOVE my GK tone and want to keep it, but I'd have to buy another 4 ohm cab to go to two speaker cabs which is where my quandary begins. Here's where I'm at on my ideas/options (please let me know if these are completely stupid or un-doable)

- Buy an 8 ohm Avatar 2x10 and hook it up like normal with the 4 ohm. Since it wouldn't be going too low (2ohm) it shouldn't damage the cab and SS heads usually auto sense the resistance? (fact check?). This may involve me buying a GK MB500 or something of that nature (maybe an RB head?), and of course the 8 ohm cab.

- Attempt to rewire the 4 ohm cab (even possible?) to make it 8 ohms. Still need to buy something like a GK MB500 and the 8 ohm cab.

- Buy another 4 ohm avatar cab, but look for a class D SMPS micro head that does decent wattage and can do 2 ohm loads. I'd go into the effects return on the 2 ohm head from my GK and then into the cabs. I can keep my GK tone this way and won't have to take risks with the cabinet ohm loads or my tone. (Suggestions for heads plz!!)

- Something else I haven't thought of!


Please keep in mind I'd like to do line array. Our rehearsal space is 10x10 and as much space as we can spare, the better. I'm selling off some gear to make this work, but want to make sure I'm moving forward with the most cost effective option.



Thanks!
- PtB
 
Last edited:
#2
You could run a series junction box, or cable, and connect two 4 ohm cabinets in series to make an 8 ohm load. This would decrease the power output of them amp, however, but it would still be a gain in volume.

I like your suggestion to run the GK into a poweramp that is 2 ohm capable and run both 4 ohm cabinets off that. Carvin, QSC, Yorkville, there are quite a few options really. If you are on a budget look used. I would not look at an additional head.

You may be able to re-wire but that is over my pay grade.
 
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#3
DiabolusInMusic said:
I like your suggestion to run the GK into a poweramp that is 2 ohm capable and run both 4 ohm cabinets off that. Carvin, QSC, Yorkville, there are quite a few options really. If you are on a budget look used. I would not look at an additional head...
Click to expand...

Thanks for the reply, DiM!

The power amp is a very sensible option, but I only had two issues with it...

1) Half my decision to go forward with this is the prospect of a vertical line array, a very lucrative option for me. Vast majority of power amps would be too wide for me to do this.

2) While I could rack everything and keep it on the floor, that's stooping down to make tweaks, another thing I'd like to get away from...which also takes up more floor space in the practice spot.


Do you know of anyone making micro-sized power amps? It doesn't have to be an ungodly 2k watts of power, the Avatars are very very efficient IME. The GK MB200 gets very loud right now, but with fuzz and other effects kicking in, I want some more headroom and power handling. This is why I was leaning towards another, inexpensive bass head that can do 2 ohms and has an effects return.
 
#4
Very few if any "micro" heads will do 2 ohms. The power amp modules are just not rated for that low a load. Only two possibilities for a 4 ohm 210 cab, 4 ohms with speakers wired parallel and 16 ohms with speakers wired in series. That is why I personally never recommend 4 ohm single cabs unless they have a lot of drivers in them (810, 610, 412).
You could use the "Chain out" from the MB200 to an MBP powered cab.
 
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#5
KevInDaBassment said:
- 1. Buy an 8 ohm Avatar 2x10 and hook it up like normal with the 4 ohm.

- 2. Attempt to rewire the 4 ohm cab (even possible?) to make it 8 ohms.

- 3. Buy another 4 ohm avatar cab, but look for a class D SMPS micro head that does decent wattage and can do 2 ohm loads.

- 4. Something else I haven't thought of
Click to expand...

1. Nope. 2.67 ohms, too low for those heads.
2. Can't: see above post... your only option would be 16 ohms.
3. Again, see above post. There may be something out there that's small that will go down to 2, but IDK of any off hand.
4. Like B mentioned, an MBP cab would be an option. Do they make a powered 2x10? You'd still be mixing cab designs that MIGHT not get along.

Sorry there isn't a way out that's less spendy. 4 ohm 2x10 cabs kind of paint you into a corner. If you are determined to go 2-2x10, you need different cabs, or another 4 ohm cab run in series. You WILL need a special cable, or an external box like mentioned to do this.

Have you considered the tried and true milk-crate? Get your 2x10 up closer to your ears. You don't need to buy a new cab or amp, and I'd bet it'll make at least a bit of a noticeable difference in perceived loudness. Heck, use a stool and get it up even higher. You probably wouldn't lose coupling with the floor with something like a 20" height stool.
 
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#6
Ok throwing out another idea...


So I HATE how high (or low?) the input sensitivity is on my Crown XLS1500 is. That does go down to 2 ohms, but it doesn't give me near enough headroom. I tried to use my GK MB200 through it one time, but I have to crank the gain on it up (I don't think it's really designed to do this) and it still wasn't getting enough juice. I have the VT Bass Deluxe, but turning up the gain and master to get it loud enough makes the preamp going into OD and it messes with how I want the sound shaped with the pedals.

Anybody know if an amp tech can change the input sensitivity on that amp so it's more usable? If so, I could just snag another 4 ohm Avatar cab and maybe a different preamp or get a used 400RB-IV or something to rack in there. Might just have to deal with the rack hanging over the sides. Just hoping it won't fall off :(
 
#13
This is what mine looks like...

GKBAck.JPG
 
#15
Maybe yours is a bit quieter. The powered cabs came out after a few runs of MB heads, maybe they boosted the output a bit for them once they started making the powered cabs? Guessing. Mine says "line out/chain out".
 
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#16
B-string said:
So you must have an early model. I don't know how strong the signal is on the early ones is but email [email protected] and he should be able to tell you. Or PM @rag here on TalkBass, but he may take longer to respond (G-K is his company).
Click to expand...

Thanks for the all the help. B-String.

Man I could KICK myself for getting a 4 ohm cab way back when. To Avatar's credit, I've had this cab for over 6 years now and it has been fantastic. You can see why I'm reluctant to part with it lol.
 
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#17
Another thought.... Maybe reaching here.....
An 8 ohm Avatar, and two of whatever speaker are in the 8 ohm cab swapped out into your current 2x10. This will really only be effective if the 8 ohm cab and 4 ohm cabs are the same design and Dave just used 4/8 ohm versions of the same model speaker. Actually, from what I've read here on TB, there's a chance the cabs are just "stuffed" anyway. IDK how true this is.
 
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#18
KevInDaBassment said:
Thanks for the all the help. B-String.

Man I could KICK myself for getting a 4 ohm cab way back when. To Avatar's credit, I've had this cab for over 6 years now and it has been fantastic. You can see why I'm reluctant to part with it lol.
Click to expand...

Yep, I understand. As you can maybe tell, I am a fan of making work what you have at hand first and foremost. The original may or may not be a balanced output as well. Those are questions Brian and of course Bob can answer. The other possibility is using the output in the headphone position as an unbalanced input to the Crown, but start with the gains all the way down incase the signal is too hot. The balanced/unbalanced question needs to be answered though before you try it. The headphone will be a stereo out so the balanced TRS cable won't work with a headphone out, TS to XLR unbalanced cable would be needed.
 
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