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mrbeezroom
New
Username: mrbeezroom

Post Number: 3
Registered: 3-2004
Posted on Friday, April 30, 2004 - 9:53 pm:   Edit Post

I'M PUTTING TOGETHER AN AMPLIFIER SYSTEM FOR BASS GUITAR. I JUST BOUGHT AN CROWN XLS602. MY OTHER COMPONENTS ARE TWO ALEMBIC FX-1 PREAMPS, A KORG DTR-1 RACK TUNER, A FURMAN PL-8 POWER CONDITIONER, AND A STARTOUCH A/B BOX. I WANT TO BE ABLE TO SWITCH BASSES TO THE AMP/SPEAKER SETUP WITHOUT HAVING TO CHANGE SETTINGS (HENCE, TWO PREAMPS). I AM USING AN EDEN D210T 8-OHM 250w AND AN AVATAR 8-OHM 4 X 10 CABINET (800w?) RUNNING TOGETHER AT A 4-OHM LOAD. CAN ANYONE HELP ME WITH SOME SUGGESTIONS FOR WIRING IT UP? I AM ALSO CONSIDERING PURCHASING AN ACCUGROOVE EL WHAPPO (800w) THAT IS SWITCHABLE BETWEEN 4 AND 8 OHMS. I PLAY AN ORION-5 AND AN IBANOWSKY 4-STRING (AN '81 IBANEZ MUSICIAN W/ SADOWSKY ELECTRONICS. THE CROWN RUNS 350w/CHANNEL @ 8OHMS, 600w/CHANNEL @ 4 OHMS, 1200w @ 8 OHMS BRIDGE-MONO, & 1680w @ 4 OHMS BRIDGE-MONO. ONE MORE THING, DO I HAVE TO RUN UNBALANCED INPUTS FROM THE PREAMPS TO THE AMPLIFIER? MY PROBLEM IS I KNOW JUST ENOUGH TO BLOW EVERYTHING UP. HELP!
palembic
Senior Member
Username: palembic

Post Number: 1317
Registered: 9-2002
Posted on Saturday, May 01, 2004 - 9:43 am:   Edit Post

Hi John,

to be honest ...I am not sure. I use my F1-X with the frequency cross-over for bi-amping. I can give a yell and ask more technical brothers to come over and see into this.
BTW: welcome to the club and I really love to see some pictures of this amazing set-up.

Paul the bad one
mrbeezroom
New
Username: mrbeezroom

Post Number: 4
Registered: 3-2004
Posted on Saturday, May 01, 2004 - 1:09 pm:   Edit Post

Thanks for responding. I was beginning to think it was my breath! The setup is really not that amazing, just need being the mother of invention. My basses are so different in tone that in order to switch in mid-set I needed to be able to be very quick. I also didn't want to carry around two complete setups. So I found a good A/B box and it works well. If you know of anyone who could give me an detailed (read:idiot-proof) wiring diagram for a Y-cord with 2 male balanced XLR's down to one 1/4" mono plug I would appreciate it. Or possibly another way to wire it up. I really would rather avoid bi-ampimg. Is it possible to put a TRS 1/4" output jack on the F1-X's? I'll post some pictures when I finish the setup, Thanks again.
dfung60
Junior
Username: dfung60

Post Number: 37
Registered: 5-2002
Posted on Sunday, May 02, 2004 - 1:08 am:   Edit Post

What you're trying to do isn't too complicated, but the components that you have aren't going to make this very easy.

The basic block diagram is simple. Bass A goes into preamp A. Bass B goes into preamp B. The unbalanced full-range output from each preamp goes into the A and B inputs on your switcher. The output of the switcher goes into your tuner. The output of the tuner goes into your amp in bridged mode. The output of your amp goes into the speakers in parallel. The AC connections all go into your power conditioner. And that's it.

If the cable runs are short (say 8' or less), then the unbalanced connectors will be fine. When the runs get long, signal loss (mostly treble) and noise may start to become a problem.

This is where your specific components start to give you a problem. Your a/b box is a floor pedal rather than rack mount. If it were a rack selector, then the unbalanced connectors aren't an issue as the cable run will probably be no more than a couple of feet. But if you need to run from the preamps to your stage position and back to the amp, you could easily be talking about a very long cable run. Also, your Crown amp only has XLR inputs, so you'll probably need at least one inline transformer to get it hooked up to the rest of the gear. The FX-1s have XLR outs that will work with the Crown amp, but this doesn't help because you really want to sum the two preamps before they get to the amp which you would probably run in mono anyway (stereo will require more speakers; biamp won't work either because you have the input selection problem again).

Life will probably be a lot easier if you can find a rack mounted a/b selector with unbalanced in and out. If you're switching mid-song, then not having a floor switching box is probably OK anyway. It would probably not be a big deal to have the guts of your StarTouch box mounted in a rack cabinet. Once you've done that, the wiring is pretty simple and cable runs are short. You'll still need one inline transformer. I guess this sort of magic box could potentially let you switch between A and B remotely without routing the signal all the way out to your stage position.

Interestingly, Alembic used to make just such a box called the IN-2 Input Module. It was a rack switcher designed to switch the stereo outputs of a Series bass. It did a lot of other stuff too that you don't need (5-pin XLR input and 3-pin XLR outputs, I believe) and would be tremendously expensive to solve this problem.

The deluxe solution would probably be to get a balanced switch box for your rack. This will definitely be a lot more bucks, but will have better performance. In this case, you will probably need the tuner on an unbalanced sidechain and, if you want to mute the amp while tuning, you'll need some sort of separate mute switch on the switching box.

The other thing you ask about - a y-cable between the two preamps - is also a possibility. To make that work right, you'll need to have a series resistor in line with the output of each preamp. I don't know what the value of the resistor would need to be to address the loading problems that you'd have from the summed outputs. This will lead to a signal loss and may have other undesirable effects on your tone. You'd probably want to do this on the unbalanced preamp outs rather than the balanced ones, otherwise you'll need two matching transformers.

Good luck

David Fung
mrbeezroom
New
Username: mrbeezroom

Post Number: 6
Registered: 3-2004
Posted on Sunday, May 02, 2004 - 1:41 am:   Edit Post

Thank you, your info actually helps more than you know. I have mounted my switchbox to the front of my rack drawer, so the cable runs are short. I am using 1 preamp separately for each bass, so stereo or summing the two isn't a problem. I am perfectly happy with my tone from just one preamp. I don't switch guitars mid-song and by the time I'm playing on stages that are so big that I'm that far away from my rig, I would hope I'd have a tech to do all of this for me! I really appreciate your knowledge & time. I'll post another message with some photos when I get this all sorted out.
palembic
Senior Member
Username: palembic

Post Number: 1319
Registered: 9-2002
Posted on Sunday, May 02, 2004 - 1:59 am:   Edit Post

Et voilą ...that's what this club is all about you have technical wizzards and technical morons, if the one helps the other ...well ...we can get a lot of a hell good sounding basses ...not the SAME sounding but ...well ...what YOU want to hear!!!!


Paul the bad one


Hehe ...I KNEW it ...iff I yell hard enough ...Brother David great info

(Message edited by palembic on May 02, 2004)
bkbass
Junior
Username: bkbass

Post Number: 29
Registered: 11-2003
Posted on Sunday, May 02, 2004 - 6:45 am:   Edit Post

Might I suggest Have Inc.com?They make all kind of custom rack stuff using only the best connectors etc.They are also a great source for wires and all is reasonably priced.
mrbeezroom
New
Username: mrbeezroom

Post Number: 7
Registered: 3-2004
Posted on Sunday, May 02, 2004 - 11:17 am:   Edit Post

Thanks! Looks like a great source. I submitted a couple of custom quotes. I'll let you know how it works out.
gbarchus
Member
Username: gbarchus

Post Number: 64
Registered: 6-2002
Posted on Tuesday, May 04, 2004 - 8:34 pm:   Edit Post

One F2B makes it a little easier. Two channels in and a mono out!
mrbeezroom
New
Username: mrbeezroom

Post Number: 9
Registered: 3-2004
Posted on Tuesday, May 04, 2004 - 8:52 pm:   Edit Post

Thanks everybody! Ron e-mailed me with a number of viable options that I'll be trying. The suggestion of the F2-B entered into my decision-making process, but the F1-X's balanced outs make them a less noisy (but more expensive)option. I appreciate all the help.
gblick
New
Username: gblick

Post Number: 4
Registered: 10-2003
Posted on Monday, May 10, 2004 - 1:47 pm:   Edit Post

The 1/4" unbalanced outs on my F-2B are so quiet that I couldn't imagine them being any quieter.

-Gus

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