HawkeyeKane
2726 posts
Mar 02, 2015
2:13 PM
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Found this on beavis audio...seems like it'd be an inexpensive, simple, yet effective build to use as a preamp in front of amps with solid state preamps like my Alamo Fury. And 12AU7's seem to have a nice warm tone to them. Thoughts?
ValveCaster Overdrive - Tube Overdrive and Boost from 9 volts
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Hawkeye Kane - Hipbone Sam
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james jeffery
4 posts
Mar 02, 2015
2:33 PM
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This looks really cool... Do you think it would work to give a "warmer" tone if you run it in front of a solid state amp?
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jj3ff3ry
Last Edited by james jeffery on Mar 02, 2015 2:35 PM
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Barley Nectar
690 posts
Mar 02, 2015
2:55 PM
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I can't imagine running that tube at 9V DC. Many of these SS amps with a tube stuck in the preamp, is just a sales gimmick, IMO. I get the impression that it is the power tubes that give the "Tube Tone" not the preamp. If you read about hybrid guitar amps, the ones which use a tube power section are the preferred units. (Music Man, Peavey) Let's see what 5F6H has to say...BN
Last Edited by Barley Nectar on Mar 02, 2015 2:58 PM
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HawkeyeKane
2727 posts
Mar 02, 2015
3:47 PM
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Goose, it looks like there's a simple voltage divider to make the voltage delivered to the tube around 6VDC. The amp I have in mind for this is indeed a hybrid with SS preamp & tube power section. I currently warm the tone with an ART Tube MP, but that only has gain & output controls and runs Av=100 with an AX7 as opposed to Av=17 with an AU7. If I could swap the tube out in the ART, I woulda done it long ago, but it's sealed in.
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Hawkeye Kane - Hipbone Sam
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HawkeyeKane
2728 posts
Mar 02, 2015
3:53 PM
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And just FYI...that ART runs off a 9VAC power supply.
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Hawkeye Kane - Hipbone Sam
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Harpaholic
648 posts
Mar 02, 2015
4:45 PM
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Hawk, you can replace the tube in the ART, I've done it. Two screws on each side. You can't take the cover all the way off because it's attached with a wiring harness, but it will allow enough space to remove and replace the tube.
I put a JJ 12AX7 in it, I can't offer an opinion
on a lower gain tube.
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isaacullah
2939 posts
Mar 02, 2015
5:34 PM
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This, and other low-voltage tube preamp designs, is operating the tube in "Space Charge" mode, which, as far as I recall, can be done with many "preamp" tubes. The deal is that you don't connect the heaters, and you run the tube at lower voltages, and they work for mild gain and overdrive. This can't be done with output tubes, which is why you have to run an SS power section after. There are several designs out there for space-charged preamps, including some kits and fully assembled boards, eg: http://www.sophtamps.ca/mambo/index.php. Google brings up many more. I remember at some point there was an Australian company building well-regarded space-charged preamps with 6111 subminiature tubes, but I've forgotten the details...
These things were all the rage 5 or 6 years back on the DIY stompboxes forum. I haven't heard much about them since. Not sure if that's cause they don't work all that well, or if they do and people just aren't talking about them anymore.....
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YouTube! Soundcloud!
Last Edited by isaacullah on Mar 02, 2015 5:40 PM
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Barley Nectar
695 posts
Mar 03, 2015
9:38 AM
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How bout that, I have never heard of space charge. More stuff to learn. Thanks...BN
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srussell
14 posts
Mar 03, 2015
12:26 PM
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Does the Art Tube Mp provide any distortion? - I play guitar as well and would like to be able to use the same amp for both (not at the same time) - and was wondering if there was a simple pedal that I can use to drive the tube tone prior to the amp driving it. Just need to dirty the tone enough to not have to swap out tubes.
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Harpaholic
649 posts
Mar 03, 2015
12:43 PM
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What amp are you using for guitar? The Art studio will increase gain to the point of your tone getting thicker and fatter, it can also make the tone warmer and add bass.
It increases the gain of the signal but It doesn't distort like OCD distortion, it acts more like a low and mid boost.
Its a great multipurpose pedal for the money and it will definitely improve tone. I just sold a set of them because I didn't need them.
Last Edited by Harpaholic on Mar 03, 2015 12:46 PM
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srussell
15 posts
Mar 03, 2015
1:05 PM
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I'm looking at getting a Vox AC4BL - It's a 4 watt vox amp. I haven't had a chance to put harmonica through it yet, but I love Vox tone for guitar. It's small and lightweight and I mainly play at small clubs and events. My fear is that I won't be able to get the overdrive I want for the harmonica though, and so I was looking at option to basically preamp prior to the amps preamp.
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HawkeyeKane
2729 posts
Mar 03, 2015
1:10 PM
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"Hawk, you can replace the tube in the ART, I've done it. Two screws on each side. You can't take the cover all the way off because it's attached with a wiring harness, but it will allow enough space to remove and replace the tube."
Hmmm...well I don't necessarily wanna tear into my ART...but I have a Behringer MIC100 that does the same thing that I wouldn't mind cracking open. I just wish it had some kind of tone control in it is all...
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Hawkeye Kane - Hipbone Sam
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Harpaholic
650 posts
Mar 03, 2015
1:21 PM
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I have a Vox Da5 and a Mini 3. There pretty decent for harp but not great. Dynamic mics work best.I use the Mini 3 for camping or a day at the lake running with a power inverter. They both have built in effects but I like them clean or through the mic channel.
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srussell
16 posts
Mar 03, 2015
1:39 PM
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The Ac4 is a 10 inch speaker and 2 12ax7's in the preamp and an EL84 for the 4 watts of power. So it should be better and warmer than the little one's. I know I could tube swap if I needed too, but would love to be able to stick another preamp in the signal path if I needed a bit more tube overdrive.
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HawkeyeKane
2730 posts
Mar 03, 2015
2:08 PM
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@srussell
You could also try a split input cable to your Vox and use preamp on one jack of it, and whatever else on the other.
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Hawkeye Kane - Hipbone Sam
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Harpaholic
651 posts
Mar 03, 2015
2:28 PM
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It should work well with that set up Russell.
Have you looked at the Lone Wolf Pedals?
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rogonzab
664 posts
Mar 03, 2015
2:38 PM
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How wel this pedal would work just as a boost? I use my HarpBreak to get my distortion, so this pedal may work as a simple boost to "warm up" the sound?
And, what "warm up the sounds" mean?
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Sorry for any misspell, english is not my first language.
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Harpaholic
652 posts
Mar 03, 2015
3:53 PM
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The ART will work as a clean boost.
To me warm is not bright, highs are rolled off,
more focus on mids and lows. More pleasent to listen to.
Tube amps are typically warmer than solid state amps.
Last Edited by Harpaholic on Mar 03, 2015 3:55 PM
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srussell
17 posts
Mar 04, 2015
6:47 AM
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@Hawkeye - good idea if I ever need it for electric guitar and harp in the same gig - although I'd probably use an A-B box.
@Harpaholic - I looked a little bit at Lone Wolf and was thinking of the Harp Attack as possible solution, but wasn't sure about other options. If the ART is simply a clean boost - which most mic pre's are then it's not really what I'm going for. I want to be able overdrive the tube in the preamp pedal so that I can get a grittier, dirty (and warmer) tone from the amp without having to swap tubes to get the gain before feedback that I want.
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orphan
425 posts
Mar 04, 2015
7:22 AM
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@ srussell
I think you will be pleased with the Harp Attack. I have used it in front of SS amps and PAs to shape tone and control gain before feedback. Nice pedal, easy to use.
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