What do you DO with ROG effects?!?

[Praying_V]

runoffgroove.com...  Tube amp designs cloned into FET circuits...

Do you use them as DI boxes, to go straight into a board?  Do you use them as a preamp, plugging straight into your power amp?  Do you really use them as an effect pedal, in you regular chain, switching it on for certain songs?  These circuits are so cool, but I've never built one, 'cause I've never been sure what I could DO with it...

[tcobretti]

Most people use them as stomp boxes, others as preamps.  I plan to build a bass amp with a power amp and the flipster as the preamp.

They sound amazing.  By they, I mean every ROG project I've built.

[Praying_V]

If used as a preamp, does the sound actually rival that of a tube preamp? I'm especially looking at the Flipster.  Could a bass player in a live rock band actually use it on stage, plugged into a power amp?  Can you use boosters & fuzz pedals in front of a FET preamp (and get a good sound)?

[tcobretti]

There are more threads on the tubiness of the ROG pedals than you want to read.  Nothing really sounds like a tube.  However, these pedals distort much like the amps they emulate, and have a similar eq-ing which goes a long way toward 'emulation'.

If you can afford it, a Line 6 Pod (or Bass Pod) is a better preamp, but if you are broke, these are a great alternative.

Re: Boosters and Fuzz.  I am not crazy about boosters and the ROG pedals because they saturate that first transistor and it sounds less tubey to me.  Fuzz, however, sounds great.

I've built the English Channel, Supreaux, and Eighteen, and they all sound great.  The Eighteen is AC/DC in a box, while the Supreaux NAILS the tone from Zep's Lemon Song.  The English Channel has a very thick Voxy sound.  At some point I will almost certainly use the Supreaux as a preamp just cause it is so unique sounding.  My Line 6 does the Vox and Marshall sounds so well that I don't need them so much; if I used overdrive pedals I would play them because they are no kidding the best overdrive pedals I have ever heard. 

[MartyMart]

I like to run these into either a "speaker sim" direct to mixing board or through a small
power amp. ( condor / Ultra-G / LM2050 based amp )
With my 'real' guitar amps, the tone is different - but not in a bad way.
They are very cool and give you the "flavor" of the amp's they emulate, sometimes quite close !

MM.

[DiamondDog]

The Eighteen is AC/DC in a box, while the Supreaux NAILS the tone from Zep's Lemon Song.  The English Channel has a very thick Voxy sound.

+1.

Remember, the way to look at these circuits is that they give you the character of the amp. Personally I've found the Supreaux to be very responsive to a lot of the things I like responsive in That Big Black Box Behind Me, and a sound I like. I have DI-d it successfully through the Condor, but such a setup would be too fussy live. Too many things to go wrong.

[Mark Hammer]

A few things to get straight.  Part of what makes a tube amp a tube amp is the output tubes and their quirks at whatever plate voltage is used, and the output transformer.  Part of what makes ANY amp sound the way it does is the speaker complement and cabinet.

The ROG circuits are great, but what they attempt to emulate is the preamp section of the various amps in question, and not the power section or sound of the speakers.  Consequently, what one uses them for is to mimic the tonal qualities of the harmonics added by the preamp alone, and whatever interesting tone shaping the circuit provides to both clean and not-so-clean signal.

Now NONE of that is a criticism.  But what it implies is that to avoid disappointment arising from unrealistic expectations, one should conceive of the circuits as simply different flavours of overdrive circuits, or alternatively as front ends to amps of other types (e.g., any low-to-medium power amp built from a power-amp chip).  It is not unreasonable to use them so as to push the front end of an already complete tube or SS amp in ways that can provide satisfying behaviour in that particular amp.  Of course at that point, one needs to stop thinking of the ROG circuits as producing the "sound" of the amp they are named after because there is, after all, another amp in series.

[WGTP]

Answer #1  I can not speak in a public forum of what I do with ROG effects.

Answer #2  I hybridize them.

Answer #3  I use 3 of their Mosfet stages in series as a distortion.

Answer #4  I appreciate them.   

[balance]

I've only made the Fetzer Valve Deluxe at this point. I boxed it up in a 1590B and use it as a pedal. For me it serves as a not so clean boost and has been in my chain since the day I built it. I mostly use it for dirtying up slide.

Brian

[DougH]

he ROG circuits are great, but what they attempt to emulate is the preamp section of the various amps in question, and not the power section or sound of the speakers.

That's not really true.

They usually have a "PI" and "power amp" section after the preamp as well as a 2 pole LPF on the output for crude "speaker simulation".

[Mark Hammer]

All true, but let's be honest that the "speaker simulator" on most of the ROG circuits tends to be the same regardless of which circuit, and the "output section" equivalent does not attempt to deliberately mimic a push-pull circuit, or the behaviour of an EL34 vs a 6L6 vs a 6V6 vs an EL84.  So, while you are correct that they are not JUST a preamp circuit with a FET-for-triode substitution, I think an honest appraisal would indicate that they most effectively and authentically aim for emulation of the front end, with some modest attempt at providing an output that is sort of like a generic miked speaker cab fed by a tube output section.  Me, I'm still waiting for folks to start dickering around with small output transformers in those circuits.  I think the results might be interesting and a step up from what is already a great start.

Again, that is not what I would consider any sort of flaw, and I'm as much a believer in the maxim that if it sounds right it IS right as anyone here.  But you and I can look at the circuits and know immediately what we do/will and don't/won't get out of them.  There are probably several hundred enthusiastic 18 year-olds here, whose curiosity led them to migrate from H-C that won't readily infer what the ROG circuits do and don't do/emulate.  For me, it is simply a question of being fair to them, and not letting them fall victim to what they don't know...yet.  I know damn well that it won't take more than a couple of years before they're all kicking my ass.

[DougH]

My point is that some of the original attempts at this sort of thing on this forum with miniboosters and so forth was just mimicking preamps. The Booster2.5, BSIAB, etc all derived from that approach. And that works fine for a lot of high-gain stuff like mesa-boogies and etc. It really depends on where the characteristic "sound" is generated in the particular amp in question. For vintage amps, a lot of it comes from PI and power amp distortion, which the ROG approach takes into account.

As far as output transformers and etc go, I don't know. I'm not holding my breath that emulating (or using an xformer in a 9v circuit) is going to make much of a dramatic difference if at all. One thing I do know is it is much easier just to build a tube amp than it is to attempt to accurately emulate it in SS, esp at 9v.

I will say that the ROG approach works well and sounds good on its own merit. And a lot of what a lot of people consider "tubey" comes down to EQ.

[B Tremblay]

I will say that the ROG approach works well and sounds good on its own merit.

It's rather amusing to see you of all people attributing the approach to us!

[petemoore]

  Here's what I did with it today.
  Remembered how much I liked the Supreaux, reading the article again, then choosing it between it and the Eighteen, close call and I ebbed toward the slightly lower gain looking Q1 and the way the Supreaux's Gain stage > Volume > gain stage > Tone > Gain Stage >Volume looks, putting the treble rolloff farther downstream than the Eighteen [plus I have an 18w amp].
  And decided to build the Supreaux again anyway, using a few different values here and there...10k's 2n2's for the two pole filter at the end [instead of 12k's and 3n3's], and a 4u7 source bypass cap on Q1...the 3k9 source resistor became 3k6, and I had to use a 47k trimpot [with optional 47k] to bias Q3.
  And opted for J201 [Q1], 2n5457 [Q2], and MPF102 [Q3] transistor compliment.
  3 X J201 was definitely higher gain and grain, I found the tone to be most 'ampy' and less 'distorter' sounding with the 'tapering gain' transistors as gain goes up through the circuit [obviously Q3's input level is much higher than Q1's and higher than Q2's],  and a bit more conservative bias [with 8.8v batt, around 450, 444, 448 IIRC].
  Really enjoying the result ! I did much better work with this one ! I believe this will be a shoe in as compliment between simple boost and distorters, the two pole filters make for a more focused voice. 

[frank]

I really like to use use FET Princeton as an overdrive. I think it does not sound quite like a real single ended tube Princeton, mainly because of its hier gain and output stage.  This circuit sound good with any amps.  Ex: the 18 used as a dist. box, if plugged in a clear Fender Twin can sound very grainy.  The Princeton is much smoother.  It may be one of my favorite dist. effect by now.

By the way THANKS to Petermoore for the input.

The ROG effects have a good point for studying the preamps architecture of many classic amps without having to deal with high voltage issues.  They are all good effects to build if you think that one day you might like to build a tube amp.  It's GOOD EXPERIENCE!   

[Mark Hammer]

I'm looking at the schematic for the Carvin Vintage 33 at the moment, which has a different sort of front end. the schematic shows a 2+2 back-to-back pair of 1N4745 diodes used in some sort of clipping manner.  I see these are 16V zeners, which would give the diodes a clipping threshold of +/-32v.  Assuming one wanted to make a FET-for-triode version of such a fron end, what sort of dioes would be suitable replacements?  Clearly you can't leave the 1N4745s in there.

The schematic can be found here: http://www.bnv-gz.de/~ooehmann/schematics/carvin/Vintage_33.pdf (Vintage 50 has pretty much the same front end).

[soulsonic]

The guitarist in my band uses the Thor I made as his main distortion straight into the front of his amp. I tweaked the filtering of the circuit a little bit to sound best with his amp and that's it! Great sounding box; covers all the crunchy to hi-gain Marshall-ish tones.

[petemoore]

  Mess with...
  Mess around with the values like transistors gains.
  Add a transistor or HF Rolloff ability.
  Stick a MuAmp on there w/Tone control. 
  See what it sounds like with an adjusted Fuzz Face driving it.
  Stuff like that.
  Enjoy the helloutta playing these 'amp in stompo-boxters' so much as to wonder why it sounds better than a regular 18W tube preamp or Tube Tweed preamp.
  Then also wonder if I'll be able to beat these tones with tubes or whether I'd even want to, pre-surmizing 'it's not possible' but having to dream about applying the ~240VDC I have set up as preamp PS in amp chassis to actual...tube preamp...like...I already have..
  Might come up with something comparable with tubes, not sure it'd 'win out' or even come close to the fun I have:
  While running it through Tube Tweed preamps with tweed output with 5881's, Alnico Blue.
  Or an 18watt preamp with 18w output section using EL84's, Tone Tubby
  Run it through the 5watt tube recto thing I have here, Alnico Blue.
  or Vox AC15 w/MM tranny's .. Greenbacks or TT.
  Probably because the tube preamps [and the power supplies that run @~ 20x the voltage] have too much headroom to really get distorting like the Jfet's @9v.
  With just a guitar pushing the Jfet circuits there's some distortion..probably more than these tube inputs are making..
 

[frank]

Me, I'm still waiting for folks to start dickering around with small output transformers in those circuits.  I think the results might be interesting and a step up from what is already a great start.

This is a good question.  I am trying to make the equivalent circuit of an out. trans. in spice and I am wrong somewhere.  I would like to use the inductance model to simulate core flux hysteresis, and also the center tap, and the software is not eating what I made, I think that I have problems with node assignations of the model (?)...

Apart for the output trans. that someone would put there, I might be wrong, but I think that there would be other filters plus small OT (no?).  But having the same kind of magnetic flux pattern in the core of the small OT would be feasible.  Different impedance matching with same frequecy transfer function and similar hysteresis curves would be the way to go.       

I'm looking at the schematic for the Carvin Vintage 33 at the moment, which has a different sort of front end. the schematic shows a 2+2 back-to-back pair of 1N4745 diodes used in some sort of clipping manner.  I see these are 16V zeners, which would give the diodes a clipping threshold of +/-32v.  Assuming one wanted to make a FET-for-triode version of such a fron end, what sort of dioes would be suitable replacements?  Clearly you can't leave the 1N4745s in there.

Now that is a good question for an exam. The first thing to do is find out what is the signal that goes through those diodes in the tube amp and have the same proportions/characteristic curve of the other diodes in the fet circuit. 

[Mark Hammer]

The curiosity about the transformer partly stems from the absence of anything that one can use as a source of "presence" the way it is used in true amplifier circuits, where harmonic components from the transformer output that are not present in the input to the transformer are fed back in varying amounts as negative feedback.  Now, whether you could get a dinky little PC-mount interstage transformer to behave like a power output transformer....that's a different kettle of fish, and well beyond the perimeter of my expertise.