Udderkuz03
8 posts
Jul 18, 2013
8:06 AM
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I have two mics. , a shire 545 and a newer shure green bullet. I run them into a bugera v-5 Watt combo with no feedback problems, just practicing at home...but I also have a line six spider IV 75 Watt guitar amp and that's where the trouble begins, feedback..I did what a tech said at guitar center said and used a direct box to take the impedance down to 600 ohms and it worked though not to sure about taking away from the microphones' performance ...what I'm trying to find out from someone who knows is if I go the other way with a line matching impedance transformer will it increase the microphones' performance, or will the feedback return? ..
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Pistolcat
440 posts
Jul 18, 2013
8:36 AM
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I'm not sure I understand the question. You have decreased the impedance from the mic to match your amp. And now you want unmatch it again? I'm not a gear guy but I bet the feedback will return. Sounds like the fault is in your amp. Maybe not good with harp? Hard to find fixes for that.
Edit: like your handle: it's like bizzarro Kudzurunner :)
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Pistolkatt - Pistolkatts youtube
Last Edited by Pistolcat on Jul 18, 2013 8:37 AM
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Udderkuz03
9 posts
Jul 18, 2013
9:27 AM
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That handle just popped into my head, plus Adam somehow reminds me of one of my cousins...and of course it seems like the feedback would return, but I heard on other posts that if you use an attenuator it reduces microphone performance...and maybe it "matches" the impedance ...
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Greg Heumann
2271 posts
Jul 18, 2013
9:31 AM
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Your tech's suggestion is just a cheap way to reduce the output of the mic, and change its frequency response - perhaps not in a good way. It makes no sense, kind of like suggesting a hemorrhoidectomy to cure a nose bleed.
A better way to do that would be an in-line volume control.
Line matching transformer and direct box are synonymous. They are both impedance matching transformers. The connector sex of a DI box is usually set up for high to low.
In any case the fundamental problem is not your mics. First - you have a 75W amp running through a single 12" speaker. That's not a great recipe for harp. But the biggest problem is that you have an amp set up for guitar, which means it has way too much gain. I don't know your amp - but do everything you can to reduce the gain - ideally to get your volume knob up to 7-8 without feedback. It won't make it louder (doesn't need to be) but it will make it possible to play much closer to the feedback threshold before it runs away from you so effectively you are able to play louder without feedback. It will also be much more manageable - it won't leap out of the amp, it will "swell." Gain is NOT the same thing as volume, nor is it the same thing as mic input level. For much more on the subject you'll find it in this document.
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/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
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Last Edited by Greg Heumann on Jul 18, 2013 9:35 AM
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Udderkuz03
10 posts
Jul 18, 2013
11:32 AM
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David Barrett recommended this amp on a site about recommended amps for harp.
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HawkeyeKane
1897 posts
Jul 19, 2013
7:28 AM
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The Line 6 Spiders are solid state modeling amps like the Roland Cubes, Peavey Vypyrs, and Fender Mustangs. Some of these can make very good harp amps. The Roland Micro Cube is a long-standing favorite around this forum. But it kinda puzzles me as to why Barrett would recommend THIS particular modeling amp for harp. 75W solid state is awfully powerful, and I can definitely see it feeding back on you before you got it loud enough to attain the tone you seek. What settings are you using on it?
When it comes to these modeling amps, I've found that 30W is an acceptable max in terms of output. ANything higher and you could be asking for feedback trouble. I used a Vypyr 15 as my gigging amp for a long time and got good results from it. But by and large, a more bulletproof method of using modeling amps for harp is to use a small portable one, and line it through the PA. The Micro Cube and the Yamaha THR10 have both seen harp-friendly tendencies in this fashion. Check out Hakan's recent Whammer Jammer video thread to see a THR10 in action.
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Hawkeye Kane
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Udderkuz03
14 posts
Jul 19, 2013
9:29 AM
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It has a master and a channel volume control so whatever sounds best balancing these. The shure 545sd plays pretty good without feedback and the newer bullet works with a guitar center live wire di box high to low(600ohms). I don't remember the site but I felt some relief when I thought I saw my amp being recommended. I started lessons with David Barretts' videos and now according to myself, there's no stopping me now...I guess I just thought I misinterpreted line "matching"and thought it would automatically adjust it's signal flow or make things smooth.
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Rick Davis
2133 posts
Jul 19, 2013
9:42 AM
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Udder, just twiddle with the knobs on the amp a lot. Try everything. The goal is to reduce gain and higher frequencies. Or, ask Dave Barrett how he does it. The guy knows amps pretty well.
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-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
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Udderkuz03
15 posts
Jul 19, 2013
1:37 PM
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Rick Davis ; it works pretty well with the mics I have. I've already fooled around with knobs for a year..taking away gain, compressor midrange frequencies..I got tired of it and bought the bugera. No problems..just backtracking to see if I presumed the wrong thing about impedance transformers ..I still use the line 6 at home(low volume) on weekends..
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