Alembic Guitars Club
Alembic products => Owning an Alembic => Troubleshooting => Topic started by: jazzyvee on November 12, 2007, 03:23:41 PM
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I have recently added a 4x10 mesa boogie Powerhouse cab to my bass rig.
I now have the powerhouse 1x15, 4x10 ( that I got off ebay this last weekend), 2x10 and Alembic f1-x and a qsc plx2402.
Now I put them all together last night and was trying to work out the best way to wire them up as a bi-amped setup.
My living room is probably not the best place to make a compariso n since its not representative of a live situation.
So far the best I've heard is the 1x15 and 4x10 in parallel off the QSC channel fed by the low out of the F1-x and the 2x10 fed off the high channel.
I'd be interested in any advice you can give on setting them up to give the best sound from my basses. If I recall correctly the full range out is out of phase with the low and high so I avoided using that output.
I'll probably have time at the weekend to set it all up for a listening test.
Just for a laugh I plugged my orion guitar into the rig to see how it sounded. It sounded like an amplified acoustic guitar Very clean and meaty.
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Bi-amping is always odd because you generally need way more power for the bass than for the highs. If I were in your position, I might try either the 1x15 or the 4x10 alone as a bass cab with a very low crossover point. Everything else would go through the other two.
Don't forget that the cabs have internal crossovers to split out the very highs. I saw something about adjustable crossover frequency selections for the horns and maybe you can play around with those settings as well.
You may find the 4x10 goes deeper than the 1x15 and it may handle more power as well. I looked on the Mesa site, but they don't publish speaker response graphs that I can find.
That's what I'd try anyway...
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I don't think that bi-amping is what you want with those speaker cabs.
All of those speakers are designed to run full range at least with regards to a bass, and crossing them over will just cause the cabs to not run effectively.
The case where this makes sense is if you are running real subs, i.e. cabinets that are dedicated to producing low end, and are designed as such. In that case, you'd run your bass cabinet (which is really a full range speaker) as the top end, and the dedicated sub as, you guessed it, the sub.
Which is not to say that you might not get some interesting sounds out of it, but I would not plan to be happy with it or for it to work. You'll likely end up disappointed, if so.
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Bradley, I think that was part of what I was trying to say, but there still might be an advantage.
If you have an 18 and a 2x10 cab, then you almost have to bi-amp. The 18 might not be able to handle anything over 2-3K and the 2x10 might not really go below 100 particularly well. Neither can handle full-range thoroughly at volume, so you bi-amp for efficiency and to feed each cabinet what it likes.
Though the speakers Jazzy has are full range, they can probably still do a better job if each is relegated to a particular frequency range. They may not go clean and flat down below 50 Hz or so, but I think they can still do a better job that way than if all the cabs are trying to carry the full range.
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Bob,
The point that I'm trying to make is that all the speakers he has are *designed* to be fed a full-range signal, and are *designed* to run from, say, 50-3K (or 6K, depending on the cab) Hz. A subwoofer is designed to run from, say, 38-110 Hz.
Those are numbers in the realm of reality, by the way-- most subs don't really run any where near 20Hz.
Since the cabs he has are designed to run full range, they aren't very likely to sound good as a subwoofer (and the midrange/top end will sound thin). Even an 18 bass cabinet will not run well as a sub-- the speaker is designed to produce full range, and the cabinet is designed to run full range. It just doesn't work right. To borrow your phrase: feed 'em what they like (full range).
But, like I said, efficiency doesn't equal interesting. You might be able to produce some interesting sounds, but I suspect that it'll all end up sounding way thinner than just running everything full range.
Speaker design is part art, part science, and all hard. Since the propeller heads at Mesa have designed their cabinets to run full range, I say oblige them.
For reference, I'm not talking about crossing over real subs-- you should do that.
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I'm with Bradley on this one. There are cabinets that were designed to be bi-amped, and there are cabinets that weren't. Adding a true sub would be the only circumstance where the complexity of a bi-amp configuration would have any benefit over a straight full-range configuration with any of these cabinets, imho.
And yes, I bet your guitar sounds wonderful through this setup!
John
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I agree with Bradley on this one too.
There are cabinet designs that need to be (or at least are best for) bi-setups. This was especially the case back in the 80's. BUT the cab's that are being made today are far superior to the cabs back in the day of bi-amp always.
I use to run an 18 ampeg sub cab with a 4x10 Guilde Hartke witha cross point at 100 and below to the 18 and everything else to the Hartke.
But with the cabs you have Jazzy I'd run then full run range. The more you play with the cabs you'll probably find that each cab (or combination of) are better suited for different size venues.
I bet that 4x10 Mesa sounds pretty good by itself.
Just My 2 cents worth,
Olie
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Gee whiz, my recent experience/experimentation with bi-amplification, and my own twisted common sense, would suggest the opposite of the views expressed here. In the late 70's I bought a well constructed custom single 15 plywood cab, with an Electrovoice EVM-II 15L, their lead guitar 15 speaker. (approx 35Hz to 5KHz). I have been very fond of this speaker in full range applications, with any amp I feed it with. Why would a cabinet designed to reproduce 35 to 5K care if the signal is only 35 -350? My instincts tell me that without the higher frequencies demands on the speaker, it could only do a better job of reproducing the lows. Same goes for my Ashdown 2x10. It seems like trying to reproduce the 35- 300Hz range would more likely add distortion to the higher freqs. I recently began tweaking my new biamped setup, a Dean Markley pre, with variable crossover from 150 to 1.5K, feeding a new Crown XLS amp. Between moving the crossover freq, adjusting the amp volume individually on the two channels, and experimenting with cabinet combinations, I have realized a wider range of tonal variation, and less mud on the bottom, and this, with a mighty big bottom. Currently I am running two single EV 15's on the lows, and a sealed guitar cab, with 2 JBL E110's on the highs, crossed over around 350Hz. It's the broadest, highest fidelity sound I've ever achieved. And running the same pre/poweramp/speakers in full range mode sounds great, but less so than biamped. I say experiment, throw convention to the wind, and let you ears be the judge. Peace, JBY
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I've let my ears be the judge... in my lounge that is and find the combination i prefer currently is the 1x15 and 4x10 in parallel off the QSC channel fed by the low out of the F1-x and the 2x10 fed off the high channel through the other channel on the QSC.
I am thinking of hiring a rehearsal room for a couple of hours one weekend and take the whole rig down there with a drummer and see how it sounds in a larger setting.
The bottom end sounds quite boomy due i think to the room being fairly small and enclosed so i need to get that out of the equation.
It stands a tad over 6' high but I doubt if there will be a reason to take the whole rig out anyway, but i guess it won't all fit into my smart car... hahaha.
Jazzyvee
(http://club.alembic.com/Images/394/45970.jpg)
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Jazzy-
I have nothing to contribute- just had to tell you that that stack is AWESOME!!! Enjoy it.
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Jazzy,
I'm happy you brought it up. I was starting wonder how your were going to fit all of that stuff in your car. I don't think a roof rack would work as I can just see your car laying on it's back like a stranded turtle. I guess your just going to have to buy a truck or van. ;-)
It sure looks impressive though.
Keith
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Hey Jazzy,
I think the 1x15 alone on the low channel, and the 2x10 cab alone on the hi channel would make a pretty killer bi-amp rig that's portable too. It would probably fit in the car, and take up less room on stage too. You could leave the 4x10 home or for another gig. Play with the crossover freq point, and sweep it up and down. At some point, your ear will say what sounds best. Probably somewhere around 200 Hz, which gives a good low foundation from the 15, and lets the 2x10 sing without low freq interference. Running both full range will do a soft cross over, because the 15 should have less hi freq output than the 2x10 and the 2x10 has less low freq output than the 15. You should be able to tell the difference: Both full range will sound fuller but more distorted (IM) Bi-amped may appear less loud, but clearer. And yes, sometimes the crossover point acts weird, and you may lose some frequencies. But here's where you can dial in an intentional low-mid scoop
(for slapping?). Your ear will be the best judge.
Kris
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The way you have it set up may sound great at home, but it won't be the best if you actually try to generate serious volume. The 4x10 plus the 1x15 can take everything the PLX2402 can put out between them and still want a little more. If they are the 8 ohm versions, they'll want a lot more. On the other hand, the 2x10 probably won't take everything the other side of the amp can put out. As far as efficiently matching the amp output to the speakers, you might do better with the 4x10 on one channel and the 1x15 and 2x10 on the other.
If traveling with all three cabs isn't going to fly, then maybe it makes more sense to figure out what combination that you can actually carry is going to work the best.
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hi, the setup i had before last weekend was the 1x15 and 2x10 which I had bi-amped. That sounded really good and the main reason I got the additional 4x10 was because I thought it would give me more punch and more sound and the stroke of fortune that the cab came up for sale at a price I couldn't let pass. The the seller only had it about 6 weeks then decided he wanted a 1x15 diesel cab instead and when he found one he just wanted to get rid of the 4x10.
So now I have it I want to get the best out of the combination of the three speakers depending on the gig. If all goes to plan with the new band I'm working with I hope to be doing quite a lot of festival gigs next year so the big setup would be good for festivals i guess.
I've read somewhere on here that the full range output of the F1-x is designed to be out of phase with the other two outputs so thats another thing to consider if I use the full range out with any of the other outputs.
As for transportation, I can get the 1x15 and 2x10 in my smart car with the bass and my mesa boogie walkabout amp. But no way would I get anything else.
I also have accesss to a larger 2nd car that I could use when I need to carry more kit but will have to have a fitting session to see what kit I can get into that car prior to me having to.
I plan to rig the thing up again tomorrow and try some of your suggestions and see what it sounds like. taking into account the coloration my lounge has on the sound.
Thanks for your input.
Jazzyvee
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If I remember correctly, the out of phase thing can be adjusted by switching the leads in your speaker cable.
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Can't I just switch the leads round in the cable between the preamp and the power amp?
It should have the same effect shouldn't it?
Jazzyvee
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Same consequence, probably more work though.
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I mean re-soldering the wires in the cable jack between the pre-amp to power amp. Not just swapping leads around as an entity..
That should put that one cable out of phase and therefore in phase with the other outputs so I can use that when using the cab full range with another cab in the low or high outs of the pre-amp.
Jazzyvee
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I think that would be ok. It's been discussed here before, so I suggest you run a search and see if you can find something more definitive from one of the electronics experts. Don't forget to mark the cable that's been reversed.
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yep sure will. Search happening now..
Thanks
Jazzyvee
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Although it doesn't address reversing the leads in the signal before the power amp, there is a reference to the phase shift topic in the Must Reads (http://club.alembic.com/index.php?topic=307) section, which points to a pretty informative thread here (http://club.alembic.com/index.php?topic=2301).
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You can invert phase in any cable in the chain to get the result you want, but that's not the best way to do this!
As has been noted in the thread, if you wire a special cable you'll need to be sure to mark it and make sure you never lose it or you'll be back at the soldering iron putting things right.
The much better solution is to open up the speaker cabinet and reverse polarity internally at whatever point is convenient, usually by swapping hot and ground at the input jack. Now, all the cables (preamp and speaker) are stone stock and you can sub with something from the big cable bag we all have if your regular cable has a problem. The change you made is safe and secure inside the cabinet where nobody can accidentally knock something loose or get it hooked up wrong.
The only way that this would cause a problem is if you share the reversed cabinet between two multi-cabinet rigs. That's pretty unlikely for most of us regular mortals.
As a side point, if you were going to hack a cable, it's much easier to change a speaker cable than a preamp or instrument cable. In the speaker cable, both conductors are equal sized regular wires, so no special work is needed to make everything fit. In most unbalanced shielded cables, one of the conductors is a regular wire and the other is the braided signal shield. If that's the case, you'll probably find it's pretty hard to group and attach the shield conductor to the center pot of the plug without inviting shorts against the plug body. You probably won't notice a shielding problem with a line level cable running between preamp and power amp, but if this were an instrument cable, you would have just defeated the shielding with a reversal like this.
David Fung
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Ok, I've just put the thing down hahaha.
I opened up the speakon connector and changed the cores over in the one end so it's reversed. Bingo All sounds powerful and much more punchy even at very low volume.So thats cool.
I took Bsee's suggestion of putting the 4x10 on full range and had the 1x15 + 2x10 in parallel in the low pass channel and that sounds massive.
With the superfilter turned in all kinds of meaty bass tones came alive.
Just as test I plugged the High out into my PJB Briefcase and that added a nice crispness to the top end but it was too hissy.
All in all I'm getting there. Once I get out on a gig with it then I will try some configurations at soundcheck if there is time.
Jazzyvee
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Thanks David!
JV; sounds like you're making progress! Which reminds me, I need to fix a few problems with my rig before the next gig.
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As with tbrannon - I too have absolutely nothing to add except I would love to play my MK signature through that stack and especially turn up at one of my gigs and shock the other three members when they see it.
I can only imagine the sound...absolutely excellent
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Hi Terry, what kind of music do you play in your band?
I have a couple of friends in Redcar that I haven't seen for a while, maybe a good excuse to go up see them and catch one of your gigs.
Jazzyvee
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JazzyVee - cheesy covers for functions & clubs, we do the odd gig in redcar..namely O'Gradys or The Clarendon, usually Sunday nights.
If you are coming to sunny Redcar give me an email(its on my profile)..could meet up and talk Alembic!!
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haha the Clarendon, I stayed in that hotel for a few months whilst I was working up at the Wilton Centre in 2003.
Some nights they had bands on which was cool.
Small world Eh.
Jazzyvee
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jazzyvee..you worked in Wilton centre!!! That is where I work!!!!! so close man!!!
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Yep I was contracted in by a local consultancy firm to do some work on an IT infrastructure and database migration project.
I used to go to Wetherspoons for my dinner in the evening then went to a couple of clubs there called Aruba's and The Deck.
Jazzyvee
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The Deck.. or the TopDeck as it was known back in the 70's.
They had two levels back then, upstairs was the general pop stuff, downstairs was the real funk music, Parliment, Bros Johnson, old Kool & The Gang(pre Joanna, Celebration)... ah memories!!!!