Please Correct Me, If I'm Stupid?

[The Ballzz]

So, given the current/recent prevalence of low wattage amps that rely heavily on the overdriving of the EL84, 6V6, etc. power tube(s) for a large portion of their overall sound/color/character, a properly operating effects loop (series or parallel) seems a pretty tough nut to crack. One of the biggest issues is that any effects loop I've seen comes before the power tube(s) and ignores the overdriven power tubes' contribution to the sound. From a layman's perspective the solution seems simple: Design/install an effects loop "AFTER" the power tubes or possibly even after the output transformer. I realize that, in practice, this may be easier said than done. It also seems that if one were to attempt this, a parallel loop may be a bit easier to do than passing the entire high level signal path through the loop. In light of the fact that there are numerous "speaker level" DI boxes on the market, it leads me to believe that deriving a line level input signal to an effects unit is not that difficult. It appears that a proper way to reintroduce that loop's signal is the main issue. I understand that what I'd like to accomplish could be done with multiple amplifiers, re-amping, micing/DI-ing one amp to drive the effects and then into another amp, etc, etc, but dragging around a bunch of gear for a 10-25 watt guitar rig is at best, inconvenient and realistically a pain in the A$$. Couldn't it be possible to make a speaker level DI type box (likely with it's own power supply) that could serve this purpose? If this could be effectively done, I'm guessing they would sell like hotcakes! Even if it were a little bit pricey, the convenience of it's use would (at least to me) make it worth every penny!
Am I Just Pi$$ing In The Wind?
Gene

 

[Big John]

...Design/install an effects loop "AFTER" the power tubes or possibly even after the output transformer...

So, you want to capture the signal of the power tubes caving in and the OT saturating but at line level, send it to outboard effects, have it returned to the same amp and then hear it back through the same power tubes caving in and saturated OT?

 

[The Ballzz]

Big John,
Kind of, but not quite like you worded it. I realize/understand that as you worded it, a feedback loop would be created. I'm thinking more along the lines of tapping the signal off the lines either going to the output transformer, or to the speaker, and then re-introducing the effected signal back onto the same lines in a parallel manner. I'm making a layman's assumption that diodes, or similar, could be used in key places to make sure that all signals and voltages flow in the proper directions to eliminate a feedback loop? I'm also assuming that it may get a bit dicey/difficult as we'd be dealing with AC as opposed to DC?
Thanks For The Reply,
Gene

 

[wgs1230]

What you're suggesting isn't electrically feasible without the use of a large step-down transformer which would add significant weight, be difficult to mount/vent and, in all likelihood, would bleed off significant treble frequency information the same way that many attenuators do when they're set for high dampening. And then there's the oscillation problem that post #2 suggests.

Notice that the manuals for most of the available attenuators explicitly warn against attempting to run their dampened signal into effects or direct to a mixer. The voltage levels are still far too high to drive those devices safely.

 

[Splattle101]

Could you not use an attenuator with a line out?

So your rig would go into the attenuator, you take a line out from the attenuator and send it to your effects, and then....send the return where? Back to another input? To the desk?

 

[The Ballzz]

To All Kind Respondents,
Yeah, pretty much what I figured. The only really effective way to accomplish "post power amp" time based effects is to either mic or DI/RedBox type device a dry amp at full tone/distortion/overdriven and run it into a delay/effects processor and then into a clean, non-equalized, non-overdriven power amp section and then into another speaker. The other way, of course, is to just use time based effects through the mixing console after a miced amp. This, however, takes the control and creative nature of the use of the effect away from the guitarist and puts in in the hands/responsibility of the "NOT SO SOUND" man!
Thanx All,
Gene

 

[Big John]

Gotcha. Only option I see here is a "pro loop". In essence, having you're own personal P.A. on stage next to your amp. RedBox (or equivalent) feeding either (1, parallel) small mixer > effects in mixer's aux loop > powered speaker(s) or (2, series) effects unit > built-in mixer on powered speaker(s). You can also place a 25k volume pedal right after the RedBox for volume control/swells of the effects, which would work for both options as well as feeding the FOH.

 

[redking]

Bad Cat Unleash or Wet Dry Rig using a basic solid state combo amp for FX.

 

[Soul Tramp]

I don't understand the need for a post power amp loop. I'm not sure one could be designed that would work properly.


For the most part power amps are used in one of two ways. The first is to drive it clean, like in a Fender Twin. The second is to drive it to saturation as in a Fender Deluxe.

If the power amp is used clean, with minimal signal distortion, have an FX loop after the power amp would be no different than having it before the power amp (as ALL loops are).

If the power amp is used saturated, the signal would likely be so mangled it would be too much a mess to run into any effects.

Again, I don't understand what would be gained having the loop after the power amp.

 

[babatube]

solution is easy and expensive.
get an attenuator with a line out.
connect line out to effects.
connect the output of the effects to another tube power amp and then to a cabinet.
it will sound like shit and worse then using a regular fx loop.
so you get the idea why it is not done

 

[Big John]

...I don't understand what would be gained having the loop after the power amp.

For convenience...

...dragging around a bunch of gear for a 10-25 watt guitar rig is at best, inconvenient and realistically a pain in the A$$...

 

[cybermgk]

As mentioned, the Bad Cat Unleash does exactly what the OP is looking for. Output from amp is attenuated and goes to an FX loop (as well as a DI out as well), then is reamped back up (if one wants). THis provides this capability for live situations. Recording, one just records the dry MIc'ed whatever and applies fx when mixing.

And the use is, many FX, pre output, don't sound all that well when the power tubes start saturating THAT signal.

 

[The Ballzz]

Cybermgk,
WOW!
Until now, I had no idea what the Unleash was and had always assumed it was some kind of low wattage amp like a Blackstar, Class 5, etc. Very cool unit and yes it does appear to do just about what I'm looking for, even if it does end up being a second power amp. The only issue is that it presents an 8 ohm load to the amp, in this case a Marshall Class 5, which has a minimum impedance output of 8 ohms. This would take away the option of using the Class 5, dry, into one set of speakers and the Unleash, all wet/effects into another set of speakers. Oh well, I've been considering an output transformer upgrade for the Class 5 for a while now and that would give me 4 ohm capability!
I'm not talking about stop box/foot pedal type stuff, but rather top end type rack mount stuff and only for delay, reverb, chorus and other time based effects. No boost pedals or dirt boxes in my universe! The Class 5 IS my dirt box! The time based stuff sounds SOOOO much better after your whole, complete dry sound is achieved, much like a sound man does at the front of house console. Doing it my way puts those effects into my hands and control.

Thank You,
Gene

 

[TeaForTwo]

Cybermgk,
WOW!
Until now, I had no idea what the Unleash was and had always assumed it was some kind of low wattage amp like a Blackstar, Class 5, etc. Very cool unit and yes it does appear to do just about what I'm looking for, even if it does end up being a second power amp. The only issue is that it presents an 8 ohm load to the amp, in this case a Marshall Class 5, which has a minimum impedance output of 8 ohms. This would take away the option of using the Class 5, dry, into one set of speakers and the Unleash, all wet/effects into another set of speakers. Oh well, I've been considering an output transformer upgrade for the Class 5 for a while now and that would give me 4 ohm capability!
I'm not talking about stop box/foot pedal type stuff, but rather top end type rack mount stuff and only for delay, reverb, chorus and other time based effects. No boost pedals or dirt boxes in my universe! The Class 5 IS my dirt box! The time based stuff sounds SOOOO much better after your whole, complete dry sound is achieved, much like a sound man does at the front of house console. Doing it my way puts those effects into my hands and control.

Thank You,
Gene

Interesting thread and problem Gene....Welcome to the forum and please do
keep us all updated on how your "problem" is resolved....
.

 

[V2]

My two cents:
the reason for putting the FX loop at the end of the pre-amp is to avoid distorting time-based effects like reverb and delay (same reason why in-amp reverb circuits come after some preamp gain stages).

The power amp doesn't really provide a tonne of gain, and so there's no problem of having the effects before the power amp.

 

[EndGame00]

I'm not exactly sure what you're looking for, but David Bray makes this neat little device called Lo-1 Line Out box where you can use your primary amp for dry signal, and a secondary amp dedicated for effects.

It looks great of an amp that has no effects loop and doesn't want to alter the organic tone..

 

[The Ballzz]

V2,
Yes, I understand what you're getting at, however, on these little Class 5 units, a major part of the distortion, crunch and color comes from overdriving that single, little EL84 power tube. So you don't end up with a full sonic picture of your sound hitting the input of a delay from any effects loop you could install in this amp or even any of the 18 & 20 Marshall style amps/kits out there, and you can often get some beats, especially when using longer delay settings. Not to mention, the power section kinda gets a bit "confused," if you will, by working to amplify dis-similar signals. It also leaves the delay sounding kind of sterile and unnatural/out of place and sounding slightly out of phase. Sounds much better after the whole sonic thing is complete.

TeaForTwo,
For now I'm just waiting for my speaker level Direct Box to arrive. I will use it between the Class 5 amp (for dry sound) and 2 of the speakers in the 1960B cabinet (or out of the unused speaker out of the amp to the DI) and run the balanced XLR output to the balanced XLR input of my Lexicon MX300 effects processor and then out of the processor into either the effects loop return of my JTM30 or power amp in of an MG100HDFX head to drive the other 2 of the speakers in the cab with a wet only signal. If the XLR input to the MX300 is too hot I can adapt it down to unbalanced 1/4" which drops the input sensitivity a few db. The Direct box has an up to -40db pad and a low pass filter to help eliminate hiss, etc. If this works as well as I think it should, I'll just deal with it, although that BadCat Unleashed is a pretty cool unit. Certainly, if I go to a bigger (LOUDER) amp for my clean sound, of course I'd NEVER do that, Ha Ha, that Unleashed is the way to go for stage volume control! I have already tried this set up using a mic on the dry amp's speaker into the input of the delay with all the rest the same as described above. It worked fairly well except for bleedage/feedback caused by miking a different speaker in the same cab as the wet amp is driving. This should be less of an issue with a Direct box feeding the effects and would also be even less of an issue if I were simply willing to haul around 2 1960B cabs!
I'll keep Ya posted,
Gene

 

[LPV]

Unleash does that and more purty darn good. But the real magic with a low watt amp is get one that's so good that it needs nothing else.

 

[redking]

Unleash does that and more purty darn good. But the real magic with a low watt amp is get one that's so good that it needs nothing else.

Agreed! To quote one of my heroes the GearManDude.... "Reverb Sucks!"

 

[The Ballzz]

OH FU@KING YEAH!!!
Well, my "cool guy" Direct box has not arrived yet, but.... a sound company buddy let me borrow a DI that's capable of accepting speaker level signal (no low pass filter or any of the other cool features) and all I can say is what I said above! Here is the setup:
A-Guitar straight (with a true bypass wah) into Class 5 driving 2 speakers of my 1960B at 8 ohms
B-DI plugged out of 16 ohm speaker jack of the Class 5
C-XLR out of DI to XLR input of Lexicon MX300 Set to Mono input
D-Output of MX300 (set to +4db) into effects return of Marshall MG100HDFX (set to +4db). This input bypasses all of the preamp but gives the surprise added benefit of being before all of the on board effects of the amp, allowing the use of the on board Flange, Chorus and Reverb which are already fairly well tweaked and suited for guitar use. There is also a separate level control for each of Chorus/Flange/Etc, Reverb and effects return. Hell, it works like a little effect mixer! The effects return is also before the Master Volume. This amp is driving the other 2 speakers of my 1960B.
E-The sound of the signal from the DI is almost a perfect carbon copy of the sound coming out of the speakers of The Class 5, except for being a tiny bit grindy on the top end. I expect that this will be easily tamed by the LPF on my soon to arrive DI. If not, a gentle bit of EQ from a 31 band will fix it nicely.
The Delay (and I expect to soon discover my Looper) works fantastically with all the fabulous harmonic goodness of the Class 5 being captured to be repeated by the delay. By far the best I've ever accomplished! I'm happier than a pig in SH!T! I do, however, suspect that to use the looper in line, I may need to switch the +4db settings to -10db.
This setup would likely work with almost anything as a second wet amp, as long as it has some sort of input that bypasses the channel EQ/overdrive/coloration. I guess there actually is a use for these horrible MG series amps, after all. And even the ones with on board effects can be had CHEAP!
Thanks For All Of Your Comments & Interest,
Gene