christopher godwin
1 post
Mar 31, 2011
6:17 AM
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"Somebody help me.." I've been playing with a band on stage lately. I am using a Fender blues deville reissue amp. There have been feedback issues. I have been using a Smartgate MXR and a bullett mic.The smartgate seems to block the feed back, but in doing so, it also blocks the
harp (ie the harp sound comes out distorted and weird)
Does anyone have any ideas re eliminating or at least controlling the feedback?
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MrVerylongusername
1647 posts
Mar 31, 2011
6:51 AM
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Just ideas
You need to reduce the work the gate is doing, so do your most to cut the feedback without it, and then reducing the sensitivity on the pedal.
Try backing off the drive and reverb from your amp. Use the EQ to control feedback by cutting the mids and treble.If you have a VC on your mic turn it to max and then turn the amp volume as high as it will go before you start to hear the ringing of potential feedback. Then back off the volume on your mic. Then try lowering the sensitivity of the gate.
Can you post a soundclip?
Last Edited by on Mar 31, 2011 6:52 AM
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5F6H
591 posts
Mar 31, 2011
7:21 AM
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Try a 5751/12AT7 in V3 next to the power tubes. You could also try lower mu tubes (12AY7/12AU7) in V1/V2. But I wouldn't go lower than 12AT7 or 5751 in V3, you're pushing your luck with the PI plate resistors if you do.
Blues Deville has a lot of gain, so you need to be very careful with the volume control, however they still kick out a lot of volume at the speakers, even with the volume knob set low. There aren't many 2x6L6 amps that are louder for harp than these...for those that are it comes down to specific amp, rather than brand or model. Don't rule out using the #2 input either.
Also consider lowering the bias current (if you have no idea what I am talking about, trust to an experienced tech)...feedback will be greatly reduced if the stock Sovtek 5881 are running at 8-15mA per tube. Lower currents will also increase crunch. You should familiarise yourself with the rebiasing procedure (buy some bias probes), Fender have made this easier by adding a bias trim pot to the RIs.
Here are some mods that work well with these amps...
Fender 1x12” Blues Deluxe/4x10” De Ville (not the ‘Hot Rod’ versions).
1) Re-bias Sovtek 5881, or Chinese ‘Coke Bottle’ 6L6 (softer attack, if a bit “fizzy”) power valves to 7-15mA for 4x10” De Ville or 15-20mA for Blues Deluxe/De Ville with 12”s, by increasing value of R87 (I would use a 100K 0.75W cermet pot, wired as a variable resistor). Fitting a resistor in parallel to R84, to reduce its value, may also be necessary.
2) Increase value of R91 to 47K 3W. You are looking for 160v (+/- 10v) on plates of the 12AX7 in V1.
3) Replace C1 with 220uf 25v electrolytic cap, observing correct polarity.
4) Increase value of R3 to 5.6Meg, or 8.2Meg 0.5W.
5) Add 330K 0.5W or 470K 0.5W resistor in series with R6.
6) Try various valves (5751, 12AT7, 12AY7) in V3 (the phase inverter, next to the power valves). I normally find that subbing V1 & V2 with lower mu valves just results in a dull tone.
7) On the 4x10” Blues De Ville, rewire the speakers in parallel for a 2ohm load. Replace the speaker jack and extension jack set up with one standard shorting jack and isolate the unused speaker taps (8ohm green wire and 4ohm green/yellow wire). Connect the white, 2ohm speaker tap and the negative feedback loop to the hot terminal of your new speaker jack socket and the black common wire to the ground & switch terminals. Later 4x10” De Villes had ceramic Eminence speakers, I prefer the Eminence Legend 102 alnicos fitted to earlier amps.
8) The Blues Deluxe also has a 4ohm speaker tap, ideal for converting to 2x10” with just a new baffle board. When taking this route I’d recommend Phillips 6L6WGB, or TAD 6L6WGC biased to 25-35mA. If you can afford a new cabinet, then 3x10” is a possibility & highly recommended. Use three 8ohm speakers in parallel off the 4ohm tap. Use a 5751 PI valve & bias Sovtek 5881 power valves to 15-25mA.
Run the amp with the ‘Drive’ channel de-activated. The effects loop reduces losses in the input circuit when using an effect pedal, but also bumps up the gain… maybe preferable for low volume situations?
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hvyj
1343 posts
Mar 31, 2011
8:24 AM
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I'm not familiar with the amp you use. But a fairly reliable method for controlling feedback is to reduce input gain from the mic. There are several aspects to this. One is to use the low gain input jack on the amp. if the amp has a volume (or gain) control and a master volume control, don't crank the non-master volume control very high.
Now, if the mic has a volume control you can reduce mic volume to "cool out" the input signal. on some mics, this will degrade tone, on others it won't. If this is problem, replace the gate with an MXR 10 band EQ pedal which has gain and volume sliders. use those to "cool out" the input signal from the mic. if the mic signal i not as hot, there will be less problem with feedback. use the freq sliders on the EQ pedal to make tonal adjustments and perhaps to notch out the freqs that are feeding back. also keep the treble setting on the amp relatively low. But lowering the input signal gain from the mic is the main thing.
I recently put up an explanation of how to use the MXR 10 band EQ like a preamp under the thread topic "Green Bullet Feedback Issue" that's a page or two back which may be useful. Hope this helps.
Using a bullet mic into a high gain amp is a combination that is particularly prone to feedback.
Btw, using a 12DW7 tube in the phase inverter slot may help control feedback and fatten tone.
Last Edited by on Mar 31, 2011 8:50 AM
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christopher godwin
3 posts
Apr 03, 2011
10:19 AM
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Thanks for the response I got re the feedback problem. Between the ideas which I have gleened from your responses, and some of my own, this is what i'm gonna do: 1) use a different amp. I bought a 40 watt Traynor. (Traynor is Canada's "fender".) This amp is not as sensitive as the 60 watt Blues Deville (doesn't sound as good either). 2) use an extension for the bullet mic to distance myself from the amp.
3) Turned the volume up full on the amp, so the volume won't have to go as high on the mic- the mic is the problem, not the amp. 4) I'm not using the MXR gate.
Some of the ideas which I recieved were pretty technical, and would have involved a lot of pyhsical changes to the Deville. I'm not playing full time with a band, and while these were probably very good ideas, It seemed like a lot of trouble foe a once a week jam.
Thanks again
Chris
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hvyj
1347 posts
Apr 04, 2011
12:37 AM
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You know, I was talking to a harp player the other day who was using a Fender Hot Rod DeVille. I asked him about it and he said he liked it and it was a good harp amp but emphasized that it was a HOT ROD DeVille and NOT a Blues DeVille and said he didn't think the Blues DeVille was a good harp amp.
I have no idea if his opinions are valid--I'm just passing this comment along for whatever it's worth.
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BigBlindRay
106 posts
Apr 04, 2011
1:12 AM
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Hi Chris.
Read this guide by Greg Heumann - It will save you a lot of hassle:
http://blowsmeaway.com/all%20about%20harmonica%20microphones.pdf
Peace.
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Big Blind Ray's YouTube Channel
Mavis and her China Pigs
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BigBlindRay
107 posts
Apr 04, 2011
1:15 AM
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@ Chris - Wether youre using a 60 watt Deville or a 40 watt Traynor - If you dont change the gain rating ie: Tube swap to lower gain tubes in PI stage (correct me if im wrong amp nazis!) Then youre still going to have inherent feedback problems.
Rule of thumb - You play harp? Be prepared to change dem tubes!
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Big Blind Ray's YouTube Channel
Mavis and her China Pigs
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MrVerylongusername
1649 posts
Apr 04, 2011
1:24 AM
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I've played through a Hot Rod Deville that belonged to my guitarist friend: it was a nightmare. Stock, they are far too hot and bright.
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Fingers
21 posts
Apr 04, 2011
3:06 AM
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This is the exact same amp i used for 6 years gigging with a LOUD!! band i used a green bullet with no volume control and all original valves in the amp! never used the drive kept the treble low this amp is loud and distorts great i still have it i haven't gigged for 2 years but cant bear to part with it, maybe you should try a few different mikes with it might make all the difference. Fingers
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5F6H
593 posts
Apr 04, 2011
4:39 AM
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BBRay: "Tube swap to lower gain tubes in PI stage (correct me if im wrong amp nazis!)" Oh, what lovely turn of phrase! :-( Edit it please.
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dougharps
61 posts
Apr 04, 2011
7:12 PM
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hvyj has some good points.
My suggestion about how to improve sound with no mods and no gate:
Try playing through the clean channel if you aren't already. Channel select button OUT. Just use the volume control on the amp, no drive. What gives tube overdrive in a guitar gives feedback in a harp mic.
Boost the lows a little (8?). Cut the treble way back at first (2?), and add a little more treble later after you have the volume you want. Same thing with presence, be moderate with presence. Set the mids at (between 5 and 8), depending on the mic. Try with no reverb until you get a better sound, then add a little. And as suggested, you can experiment with cutting back on the mic volume a little.
This should give you a place to start tweaking the settings to get the sound you want. Each mic/amp is a different mutually interactive combination. It is all dynamic, and one setting effects the others.
I hope this helps. Please let us know! I would be surprised if this doesn't help, but if it does or it doesn't, please post and tell me and the others.
PS Watch out for the obvious feedback problems: be careful about cupping the mic(get a good seal), don't point the mic at the amp.
Some players stand beside the amp so they are outside of the hourglass shape of the projected sound from the amp and can get higher volume without feedback.
h
>I<
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Doug S.
Last Edited by on Apr 04, 2011 7:17 PM
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boris_plotnikov
500 posts
Apr 04, 2011
7:56 PM
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To aviod feedback I always put amp on the floor, tilt it back. I also have Roctron Hush, which helps against feedback a little, MXR six band EQ, to reduce frequencies which feeds back (usually 3,2kHz slider) and to boost frequencies I want more (usually 200Hz, and 1,6kHz sliders). Harp Attack allow me to have more dirt without cranking up amp, but I don't use it with tube amp in loud conditions. I also often use two amps. Each is not loud enough, but together they're louder and cuts the mix better.
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