Best overdrive unit for tube amps

[zeppman]

Anyone have an opinion on the best overdrive/distortion unit to put infront of a tube amp?  Is it the tubescreamer?  I've always used my amps channel distortion...which leads me to my next question.  Why use a stompbox (solid state distortion) if tube distortion is supposed to be best?

[vanhansen]

It all depends on what you're looking for.  The most common use for overdrives is to push the input to the amp right to the edge or over it.  This is wonderful with tube amps when you are already overdriving the tubes.  They just push them more.  The most popular ones commercially available are the Tube Screamer or Boss Super Overdrive, and now the MXR Zakk Wylde Overdrive.  In the DIY community, the options are endless (ROG Tube Reamer, AMZ OD Pro, Easy Drive, etc., etc.).

Pro rig example: Zakk Wylde.  He uses a JCM800 2203 with 6550 power amp tubes.  Now, the 2203 has good gain, but not enough for the searing metal that he plays with Ozzy and BLS.  So, for years he used a SD-1 to push the amp over the edge.  He now uses his MXR ZW-44 pedal, which is really a SD-1 with some differences (search the archives for what those are).

All three examples I mentioned have different characteristics even though they are very similar circuits.  It all depends on whether you like the sound of symmetrical or assymetrical clipping, and what tone you're looking for.

I myself use a modded SD-1 in front of my Marshall but I am going to pick up the ZW-44.  Heard good things about that one.

[Dragonfly]

many people...myself included...like to use a good "boost" pedal to push a tube amp, instead of an overdrive !

andy
dragonfly fx

[Paul Marossy]

There's always the good 'ol TS808 Tube Screamer...
Or the AMZ Mini Driver...
Or the Z Vex SHO (not DIY, but worth the money)
Or several others you could build.

[onboard]

I'm glad I glanced at this again before posting what I just typed. Compared to vanhansen's specific examples, it sounds like a reply straight from the desk of Mr. Vague. I wasn't going to get into specific pedals, but that does seem more helpful.

I've played certain tube amps that I'ld never put a pedal in front of, just because the amp itself sounded fantastic to me with the gain cranked.

That said, a Fuzz Face and a Tube Screamer sound completely different in front of my tube amp and I love them both - each for it's own personality.

Is that too touchy feely?

[The_Philth]

The "best" overdrive or distortion box is of course entirely up to your ears to decide. I use an all-tube amp and I've tried both amp gain and a distortion though the clean channel and so far I've been stuck on using the LEAD channel just slightly dirty with an MIJ Ibanez Super Tube STL in front and I've gotta admit; that set-up sounds in-fuggin-credible!

Many years ago I would use the STL for a boost in a Latin Jazz ensemble, so when that band went away my STL went away as well. I found it in storage recently and I tried it in my current set-up (I currently play progressive Rock) and my tone is beautiful.

Usually, the cats that use the distortion into the amp setup would be playing some type of Metal, or they’d just get themselves a Boogie Triple Rectifier. Using a distortion pedal has different sonic characteristics than using the amps distortion. Sometimes you just can’t get that “chugga-chugga” power from the amp alone, thus lays the distortion box or amp distortion conundrum.

I can also achieve nice, clean bluesy tones with the STL as well. I mean very nice tones. Glassy, crisp, crystalline tones that emanate from pushing the Clean channel of my amp which reminds me so much of a late 70’s Fender Super Twin Reverb I had once upon a time.

Tube distortion is nothing but close to Heaven, but sometimes it just aint enough distortion to knock someone’s teeth out. People use distortion boxes in the amps dirty channel for that extra boost or they'll just use it in the Clean channel for the independence of the distortion box.

I know this reply isn’t really answering your question, but I figure I can provide my two cents considering that I recently stumbled upon the ol’ “Overdrive-in-front-of-the-amp” technique again and fell completely in love with the response I got.

So, in *my* opinion, the Ibanez Super Tube is an excellent overdrive to run in between my guitar and amp through the amps' 'dirty' channel to push the tubes a bit more and attain that “boutique/Boogie/Soldano” tube-amp tone and grit. The feedback/sustain I get with this setup as well is beautiful. I mean, at decent volumes I can sustain some killer notes that I wouldn’t be able to with the amp alone and playing along to “Europa” has never been more appealing.

[vanhansen]

Oh yeah, a nice boost does a good job.  My Marshall jumps through the roof with Gus's NPN boost pushing it.

onboard, I know what you mean about sometimes not needing them.  A great example of this is the Zinky amps.  Those little 1x12 tube combo's just rock.  Man, if I could get my hands on one.

[Paul Marossy]

Oh, stoopid me  - a Shaka Tube can sound very cool, too. You can set it for all sorts of different tones. One of my favorites.

[R.G.]

Let's turn it around - what tube amps sound better with a booster driving them?

It's not widely appreciated, but a 12AX7 input stage clips more softly when driven from a lower impedance source. Many if not all amps use a series 68K resistor in the input stage. Lowering that can make your booster clip the input stage more softly.

[j0shua]

Good Question ..... I like my Own AMP DRIVE CHANNEL , and about pedal , the best for me is MXR Dist. +


but is just the taste of player

[petemoore]

It all depends on what it depends on.
 Amp Type and settings...WIDE differences here...I have a BMP sounded fantastic for the first time ever the other day...MKII 50w settings and BMP tone control settings got this chain to really Rock Smooth !!!  Before that I thought BMP sounded like POOP through my rig...way to glanky highs etc.,,,That BMP, or with those settings would probably start at point A [Pooptone] through another amp with other settings...
 Let us know the amp, the type of sound [you want and what you're getting], and guitar[s...maybe we can be more specific about suggesting circuits in our replies. Also what effects you have and currently like/dislike.
  usedAnother question I suggest is: How do I get perfect' clean-ish, Medium Gain AND High Gain Crunch...with one foot tap between each ... this adds a whole new parameter to the ballgame...!
 If you state what your amp is, what type sound you want to get, and basically how close the amp gets to that already...
 Say if you have an amp with tube type Dist, clean or nasty, a booster may be just the thing to nastier it up a bit.
 If you start with a sort of clean-ish amp 'distortion' [like a bassman say], you may find that a FF gets all kinda tones from bright clean to saturated clipping.
 If you want bedroom distortion [the kind that happens mostly 'in the box' as opposed to 'in the amp'] you may find diode to ground clippers like DIST+ to do that trick.
 You want amp like tube tone, maybe try multiple Jfet type builds.
 BSIAB
 DIST+ Types [I like DIST+, modded abit, and LIquiD Drive...yeah]
 FF [best with tube amp in some peoples 'opinions'...highly variable results...depends on FF, amp, guitar, etc.].
 TS Types [Tubescreamer and diode in feedback loop of OA circuits]...you may be able to start and end your TS foray with a Tube Reamer [ROG}...I've tone TS, SD-1, Reamer, Alexa, and others...all a bit different...

[The_Philth]

Let's turn it around - etc...

Please elaborate further Mr. Keen, for I'm a total moron and what I just read from your reply, my brain processed it as 'Blah blah BLAH blah blah...'

Nonetheless, it attracted my attention... please... tell me more (like a junkie needs his fix)!

[ESPguitar]

Let's turn it around - etc...

Please elaborate further Mr. Keen, for I'm a total moron and what I just read from your reply, my brain processed it as 'Blah blah BLAH blah blah...'

Nonetheless, it attracted my attention... please... tell me more (like a junkie needs his fix)!

:wink:

[Paul Marossy]

RG has brought up a very good point. What he means is, that if you lower the value of the input resistor, it will make your amp clip more softly. Most amps traditionally use a 68K input resistor in series with the input signal. If you lower that to 56K, 47K or maybe even 33K, it will change the way your amp handles the clipping that occurs at the start of the preamp section. This is an intriguing idea. I may just try this on one of my amps.

[R.G.]

A vacuum tube generally works with its grid more negative than its cathode. It does this because the grid voltage being more negative than the cathode throttles back the plate current and can eventually cut it completely off.

If the grid is more negative than the source, then no grid current flows - the grid is like an open circuit, very high impedance. If the grid gets positive, then the electrons from the cathode start being attracted to the grid instead of repelled from it and grid current starts flowing. The grid goes from a resistance of a gagillion ohms down to a few K, and a nonlinear few K. Bad juju indeed.

If you drive the grid from a high impedance source, like a 100K resistor or a 62K 12AX7 plate, then the grid being driven goes from infinite impedance to a few K and the driving source cannot supply the current to drive the grid positive. So the grid hangs up right there at Vgk=0.

However, if you had a low impedance source driving the grid that could drive it above 0V and eat the electrons the grid is collecting, then the grid would go positive.

In going positive, it attracts electrons more; however, the grid is a quite open screen of wire. Most of the electrons it attracts simply miss the grid wires and get flung into the 'way positive plate. So a positive going grid *still* causes plate current to increase as long as the cathode can supply electrons. This is not as efficient as with negative grid voltage, so the amplification is less and the reprduction is squashed up there - very, very mild clipping. (!!!!!!!!!!!!!HEY!!!!!!!!!!!!!!!)

So by using a booster with a bigger output and low impedance, you can make your input stage 12AX7 clip more softly than it otherwise might if you have lowered that 68K resistor so it doesn't choke things off.

[zeppman]

Great info guys!  Maybe you could help me out a little more.  I play an amer strat through a boogie mark iv.  I want something creamy and rich, like david gilmore.  I don't play any thrash or metal...more of a jam band.  Any thoughts on what I could build to achieve this?

[Paul Marossy]

That's an interesting little secret RG!  

To answer that question zeppman, we need to have some idea of what amp(s) Gilmore uses. I am thinking that maybe it might be a HiWatt amp...

[Doug_H]

That's an interesting little secret RG!  

To answer that question zeppman, we need to have some idea of what amp(s) Gilmore uses. I am thinking that maybe it might be a HiWatt amp...

With lots of pedals...

Doug

[Paul Marossy]

Well, I have seen a diagram of his rig once, and he sure does use a lot of pedals. I can't remember anything about the amps that he uses, though. I'm sure it must be a combo of amp and some pedals.

[petemoore]

Cooleo...good toknow...just zipped up the MkII after a thorough Ch1 bottom input tracing, board inspection [the 68k is right there, with enough room atop the board to 'tag' a parallel right to it N/P] and final [hopefully final] voicing/function modification.
 I'd tried the mod, as suggested in an amp forum, and that helped. Channel one as shown has rediculously high treble, 'spike in the forehead' it was called, and was. Still the volume control's touchy spot [scritchy pot wafer...] left the choices around not enough treble or 'take your head clean off...'
 Today I approached it like I would anything else...I figured out to put a jack in the bottom ch1 input, to negate connection to ch1 TOP input, thereby I was able to trace ch1 wire to a single 68k...the one I probably shouuld have parallel/lowered with say...well, I'd grab a 68k and parallel a 100k, measure, try a 120k or 82k...measure with DMM...cause I'm 'lazy' at math, I let the resistors and DMM do it for me...lol !!!
 At any rate, all the capacitors came off of Ch1 pot, then, after tasting a few while dialing the knob up/down, a 1n - 1000pf AVX Boxed Metal Film  cap was placed across it's outside lugs...the knob has no 'WhAM-Gotchas'...didn't even notice the 'scritch' at all [It was near fully CCW], and I'm seemingly getting plenty of high end !!!
 Not that I recommend dealing with potentially lethal voltages...makes Me nervous, I don't particularly like doing it, but getting yer amp 'right' is a really good thing to have done...
 Most amps aren't so 'funny' like the MkII, and all the control knobs are 'right' enough to work with easily..as shipped, stock....that 68k mod though...you can bet that's on the list...