Double Bass How about this for a rig? (ATTN: ELECTRONICS TECHIES!!)

[Gilbert F]

Ok, so I've had my Double Big Twin for a couple of months now, and I have to say I'm not as thrilled as I was initially. It's a pretty good pickup for the price, and it handles arco and pizz pretty well, but I'm still not too happy with the sound. It also isn't resistant enough to feedback for my purposes (which isn't even THAT loud anyway, dammit!!!) I could go on and on, but I won't.

So anyway, the DBT couldn't get loud enough for me on a recent gig, so I had to go through a Shure Sm58 into a medium sized PA, and it sounded WONDERFUL. I don't want to buy a PA because they're expensive, big, and heavy, and I really like my iAMP 800, so do you think it would be possible to run a relatively cheap mic like the sm58 (cause there's no way I'm dumping 700 bucks or whatever on a Neumann) into a $50 mic preamp such as Invalid Link Removed or Invalid Link Removed and then running it into my iAMP? I know that the iAMP has a pretty flat frequency response, so I would imagine that it would be able to work. Does anybody have any thoughts on this? If I'm right, then I'll have a rig that sounds pretty close to the acoustic sound of my bass, with hardly any possibility of feedback because I usually don't play higher than moderate (jazz) volume levels.

Thanks

 

[Chris Fitzgerald]

SULLIVAN - there's no reason why you shouldn't be able to do this, although I don't much dig gear by B*******r, as it's kind of the "Cremona/Palatino" of audio. The ART should be fine. I've seen Drew Gress play through a 58 stuck into his tailpiece more than once, and he always sounds good. Two things to consider:

1) In order for this to work, you'll need to make sure you're getting a decent input impedance match between the output of the pre and the input of the iAmp. This stuff is way over my head, but if you're lucky one of our friendly neighborhood techies like e=mj2 or DRURBELCH will wander by and help you set that issue straight.

2) Part of the reason a PA sounds so good is because the speakers are usually full range and up off the ground away from your bass. I've been putting my speakers up on PA stands for about a year now, and have pretty much eliminated feedback from the equation as a result, since the sound never gets driven back into the bass or the path of the mic. Good luck, and let us know how it all turns out.

 

[Uncletoad]

I've been putting my speakers up on PA stands for about a year now

Huh. How did I miss that you've been doing that. I need to know more. Like, how, what stuff, maybe a pic if you've got a minute.

 

[Chris Fitzgerald]

Huh. How did I miss that you've been doing that. I need to know more. Like, how, what stuff, maybe a pic if you've got a minute.

Hmm..no pics yet, but the rest is pretty easy: You get an aluminum (that's "aluminium" for Bruce) folding PA stand, which weighs about 3 lbs. You attach a mounting flange to the bottom of the speaker - I had mine installed into the speaker cabinet, but the external ones should do fine. Then when you get to the gig, you just unfold the legs and pop the speaker up onto the stand at any height above about 42". I use either a VL108 or 208 for this, driven by a Focus 2.

The cool thing about it is that you almost never get any feedback even with a mic (AMT here), and you can hear as much of the bass as you want since it's at ear level. Too little bass in the monitor? Swivel it toward yer ears. Too much, swivel it slightly away. Front men seem to like 'em, too, since they can hear the pitch better and the stand helps control boominess.

 

[Uncletoad]

You attach a mounting flange to the bottom of the speaker - I had mine installed into the speaker cabinet, but the external ones should do fine.

Yikes. You cut a hole in a VL208?!! Isn't that like sacrilidge or something.

That is interesting stuff. I know my bass sounds best in my studio. The monitors are up on the desk. They are big old JBL's with 12's. It gets loud and really clear in a way I can't seem to get on the gig.


I'm going to try to get on the pole.

........Except for the hole thing.

 

[Chris Fitzgerald]

Yikes. You cut a hole in a VL208?!! Isn't that like sacrilidge or something.

Sorta, but since I had two and didn't plan on selling either...

I'm going to try to get on the pole.

........Except for the hole thing.

Yeesh, I ain't touching the first line. But seriously, I got an external flange mount that I'll bring up and leave with Nnick next time I'm up that way. You'd have to find a way to mount it on the bottom of the cab, but you could probably do it with four wingnuts or something.

 

[phlybass]

Morning!

Chris, after reading of your method, I did it this way. I had a couple of the external flange mounts that came with some Ramsa's that I used as monitors. I drilled into the speaker cabs and mounted some "T-nuts" from the inside for the wing nuts to screw into to mount the flanges. When not using the flanges, I have some Nylon bolts the correct length to use to fill the holes in the cabinets.

The only hassle is getting to the inside of the cabinet to insert the "T-nuts"... not really a big thing, and just about zero intrusion into the internal acoustical path either with or without the flanges.

Regards, Alex, aka phlybass

 

[Chris Fitzgerald]

Alex - that sounds like a great method. I don't mind the internal flange on my main speakers (less hassle getting to the gig), but because of the way the 208 is constructed, the balance of the internal flange is off, which causes the whole thing to list slightly to starboard when up on the stand. It's not tipsy and doesn't affect the sound, but it does look a little funny once you notice it.

 

[Gilbert F]

Originally Posted by Christmas Fitzgerald
SULLIVAN - there's no reason why you shouldn't be able to do this, although I don't much dig gear by B*******r, as it's kind of the "Cremona/Palatino" of audio. The ART should be fine.

Ok, ART it is, then.

1) In order for this to work, you'll need to make sure you're getting a decent input impedance match between the output of the pre and the input of the iAmp.

Well, the output impedance of the ART is 300 ohms, and the input impedance on the active input of the iAmp is 10,000. I, being a complete novice to all that kind of stuff have no idea if it would work, but I do know that you can successfully run a 10 megohm peizo pickup into a 1 megohm input. That's a difference of 9 million ohms, whereas the mic preamp into the iAmp would only be a mismatch of like 9,700 ohms. But hey, I have no idea what I'm talking about. Can anyone help me with this? I want to know if this will work before I spend a bunch of money.

 

[fdeck]

Ok, ART it is, then.



Well, the output impedance of the ART is 300 ohms, and the input impedance on the active input of the iAmp is 10,000. I, being a complete novice to all that kind of stuff have no idea if it would work, but I do know that you can successfully run a 10 megohm peizo pickup into a 1 megohm input. That's a difference of 9 million ohms, whereas the mic preamp into the iAmp would only be a mismatch of like 9,700 ohms. But hey, I have no idea what I'm talking about. Can anyone help me with this? I want to know if this will work before I spend a bunch of money.

"Matching" is a misnomer. You can generally plug a low-Z output into a high-Z input with no ill effects. It's going the other way around, high-Z into low-Z, that is a problem.

 

[Chris Fitzgerald]

"Matching" is a misnomer. You can generally plug a low-Z output into a high-Z input with no ill effects. It's going the other way around, high-Z into low-Z, that is a problem.

Your honor, I'm just a caveman.

So any low-Z preamp would be fair game going into most amp inputs as long as you had an xlr to 1/4" transformer whatchamhoogie, or am I reading this wrong? I've tried this on numerous occasions - sometimes it works really well, and sometimes it sounds like sphincter fumes. I've never quite been able to figure out why. In the latter case, is it more likely (in general of course) a matter of a pre with a color I don't care for, or an impedance mismatch? I suppose it could also be a gain staging issue.

 

[fdeck]

Your honor, I'm just an ex president.

So any low-Z preamp would be fair game going into most amp inputs as long as you had an xlr to 1/4" transformer whatchamhoogie, or am I reading this wrong? I've tried this on numerous occasions - sometimes it works really well, and sometimes it sounds like sphincter fumes. I've never quite been able to figure out why. In the latter case, is it more likely (in general of course) a matter of a pre with a color I don't care for, or an impedance mismatch? I suppose it could also be a gain staging issue.

If the preamp has an XLR output, you could just go with an XLR to 1/4" adapter cable thingamabob and skip the transformer whatchamahoogie. If the preamp has a 1/4" output, use that instead. It could be that the preamp output is strong enough to cause distortion in the transformer. Plus, the transformer is adding gain that could further threaten to distort the front end of your amp.

The most prolific sphincter in bass gear is gain staging issues (including signal level through that transformer). If the bass amp has an input pad switch or an "active" input, you could try those. Also, try going into the effects return.

Next is the pre color issue. If you don't like it, then all bets are off. But you have to resolve the gain issues before you can give the preamp its day in court.

 

[Chris Fitzgerald]

If the preamp has an XLR output, you could just go with an XLR to 1/4" adapter cable thingamabob and skip the transformer whatchamahoogie. If the preamp has a 1/4" output, use that instead.

This makes sense, as I've always had better luck with the 1/4" outs. But what is a "1/4" adapter cable thingamabob" exactly? I'm not sure I've ever seen one, having always used a transformer whatchamahoogie - probably out of fear that the impedance police would bust me if i didn't.

It could be that the preamp output is strong enough to cause distortion in the transformer. Plus, the transformer is adding gain that could further threaten to distort the front end of your amp.

Before the front end of the amp actually clipped, could this cause an "overly hot and kinda gooey" type of sound (sorry for getting all technical on you)? If so, I think I may have experienced this.

 

[seanm]

Ok, I have an ART Tube MP and a Shure SM58 and an iAMP 500, so I tried it.

There are actually two ways to go. You could keep the ART turned down and run it into the bass input. Or, if you are willing to give up the EQ, it might be better to run it straight into the effects return.

I tried it straight into the active input. I had to be careful about feedback but it seemed to work well. My wife is just going to bed so I didn't try it into the effects return. I also couldn't turn it up too loud.

However, at a rehersal space (i.e. bassment) I sometimes run my P bass into the MP into a power amp. Before testing this out, I tried it at home running the MP into the effects return of the iAMP. Works well but you have *no* EQ. Luckily the bassment is very acoustically neutral so I don't need EQ.

I also have a very clean preamp that I use. The ART MP is noticably darker than the clean preamp.

 

[karlgustav]

hi

about useing the speaker stands.I looked into it a littel bit,and would apriciate some
what kind,or wich brand are you useing?

"You get an aluminum (that's "aluminium" for Bruce) folding PA stand, which weighs about 3 lbs."
-3 Ibs seems really atempting,but the ones I hafe seen weight around three times taht

maybe you could recomend a site,or a place to buy these things?

also is anyone useing a cart or mounted wheeles or something like that ?
to make the trip from car to stage as easy as it can get

 

[mje]

Some notes about impedance matching:

One of the main concerns is having enough current to supply the next stage. (High impedance = high voltage/low current. Low impedance = low voltage/high current.) If you connect a pickup with an output impedance of 5 Megohms into an amplifier with an input impedance of 1 Megohm, the pickup can't supply enough current to the amp, and the waveform is distorted.

A piezo pickup can generate over 60 volts on peaks- I soldered a Kynar film transducer to a neon lamp to demonstrate this- but almost zero current. The preamp's job is to supply the missing current. It doesn't take much- note that fdeck's design supplies less than a milliamp- but that's far more than the piezo can supply.

Condensor microphones are similar; they actually generate almost no current whatsoever. That's why they have a preamp built into the microphone, to turn that high voltage/zero current signal into a low voltage/high current signal.

More current lets you drive a longer cable without losing highs. That's why microphones- with output impedances in the 50-150 ohm range- can easily be used with 100' cables, and guitarists, with their 250K output impedances, get so picky about the sound of their 15' cables.

When voltages are very high, and current very low, the losses can be great even over a short distance. That's why piezo preamps should be as close as possible to the pickup, and why condensor microphone preamps are built into the microphone.

Beyond the issue of matching very high impedances, generally you're safe so long as the source of a signal has a lower impedance than whatever it's plugged into. The typical bass guitar pickup has an output impedance of around 250K, and the typical bass amp these days has an input impedance of 1Meg.

Sometimes a pickup is designed to work best into a certain range of input impedances; then you can run into trouble . (Phono cartridges- remember LP records? - are designed to work into a very specific input impedance.) Generally, though, you're okay so long as the you follow the lower -> higher rule.

 

[Tom Baldwin]

Sorry to get off on a(nother) tangent here, but what is the most basic equation one needs to know in order to begin to understand electricity? What are the components of the equation, how are they abbreviated, and what are they measured in? You know, I read these words like volts, amps, ohms, watts, impedance, current, etc. and it might help if I had just a rudimentary knowledge of how they interact mathematically speaking.

Thanks in advance.

 

[tombowlus]

Your honor, I'm just a caveman.

LOL!!! I use that line a lot, and no one ever gets it.

 

[Chris Fitzgerald]

hi

about useing the speaker stands.I looked into it a littel bit,and would apriciate some

-3 Ibs seems really atempting,but the ones I hafe seen weight around three times taht
maybe you could recomend a site,or a place to buy these things?

I'm using an Onstage brand, but they don't list the weights for those. While I haven't weighed it, I can pick it up with my pinky finger, hence my guesstimation.

Invalid Link Removed one that looks a lot like mine and includes the bracket, but is listed at 6 lbs. I don't know if I could pick it up with my little finger, but I'm pretty sure it's very similar.

also is anyone useing a cart or mounted wheeles or something like that ?
to make the trip from car to stage as easy as it can get

Yes. The one I use looks a lot like [Invalid or Expired Link Removed].

Sorry for the further thread derail, but in a weird way, it is all sorta related using a mic, since I believe that getting the speaker up above the mic is essential to feedback reduction.

 

[bassame]

2) Part of the reason a PA sounds so good is because the speakers are usually full range and up off the ground away from your bass. I've been putting my speakers up on PA stands for about a year now, and have pretty much eliminated feedback from the equation as a result, since the sound never gets driven back into the bass or the path of the mic. Good luck, and let us know how it all turns out.

The discussion has addressed the first point [impedance matching] and the second part of point two. On the subject of PA speakers, the Bose 802 looks interesting (4x4.5" drivers, 31 lbs) but heavy, in fact all the useful PA speakers (EV, JBL, Yamaha) seem heavy when you add the amp, and the stand, and the pre-amp.