FX Loops

[Kaiowas]

Here's asimple question, What are the FX Loops for (i.e. In an Amp)? What improvements do they offer?

Thanks!

[donald stringer]

Effects loops are a portion of the guitar signal [taken after the pre-amp and before the main amp]  they are arranged with an output 1/4 inch jack after the pre-amp and effects return going back to amp. So you can insert your stompboxes into the signal path,midway as opposed to having all your boxes before the amps input. Most prefer modulation effects after the pre-amp.  A common rule to follow is gain producing effects before the amp input. Compressors/wah/distortion/ eq. Slam the pre-amp with a hot signal [especially tube amps] and put reverb and delay in the effects loop. My fender 185 has an adjustable effect loops , this pads the signal at either -10 -4 or line level or above , inorder to make your effects more prominent in your amp tone, via the speakers. A couple of years ago I did some missionary work[ construction,concrete, drop ceilings etc. on a mission there. The american missionarys name was michael but anyway I wasnt there long enough to enjoy the country. As there was some internal warring there at the time between the rebels and gov. forces. I hope this answered your question

[Peter Snowberg]

One of the major benefits of an effects loop is that the pre-amplified signal is used to drive the effects so you get less noise and you can take better advantage of the dynamic range of the effect and get less noise.

take care,
-Peter

[Kaiowas]

Thank you guys...

But if you have a preamp, that would avoid the need on the fx loop, wouldn't it?

[Peter Snowberg]

One other thing that goes on in guitar preamps is tone shaping. If you want your delay based effects to be as clear as they can be, an effects loop comes after the tone controls so that remains the best place to put them.

In the end you will hear a little difference between different effects placements, but the tone is up to you so whatever sounds best to you is best.
%W>eke care,
-Peter

[Kaiowas]

Well, i guess i've got only one question left.

It is possible to add and FX Loop to a preamp that doesn't have it, or it is to much?

Thanks again, and pardon my excessive curiosity!!!

[Kaiowas]

I swear this is the last one!!! :oops:

The Alembic 2FB is a guitar or bass preamp?

[Travis]

The Alembic 2FB is just the front end of an early Fender Champ/Princeton.  You can raise the value of the tone-shaping caps to make it better suited for bass.

[Peter Snowberg]

You can add a loop to any amp fairly easily. All you need to do is to tap the signal between stages and make sure the signal is passes through coupling caps so that you don't get any DC on the loop input or output. Check out the schematics of add-on effects loops for tube amps and you'll see lots of similarities between designs. If you can point to a specific schematic, I can help to point the way, but the best place for this type of information is at http://www.ax84.com

The F-2B is mainly a guitar preamp, but tiny changes will make it good for bass too. The circuit is taken directly from the first two stages of a Fender Dual Showman amp. It is very similar to dozens of Fender amps. If you increase the size of the cathode caps you'll get more bass, but it will work fine as it is. You can check out the Fender schematics here http://www1.korksoft.com/~schem/fenderheaven.htm and copy the first two stages of any of these amps.

Please don't ever worry about asking questions here. That's what these forums are for!

Take care,
-Peter

[Mark Hammer]

FX loops have multiple roles.

1) Take advantage of what the distortion from your guitar amp's input stage sounds like when altered by an effect, rather than effecting first then trying to distort.

2) Useful for incorporating rackmount, or table-top effects into your rig (hard to patch them in between your wah and fuzzface on a pedalboard).

3) Feeding your power amp inputs from other sources, such as a different preamp.

4) Feed your preamp signal to another power amp, or a mixing board.

5) Do "post-production"-type effects where an effect is superimposed over everything after the preamp.

...and more.

Some other advantages of FX loops are that they often include send and return level knobs, which permit both boosting and padding down.  

As well, some FX loops will allow you to mix in another source along with whatever is coming out your preamp.  For example, reverb generally sounds better when it is clean.  So, a better-sounding reverb can be produced if you split the guitar signal and feed a clean unaffected version of it to a reverb unit, and mix that reverb signal back in with whatever you've tortured and distorted along the way at the "Return" jack.

[donald stringer]

I remember talking about before, I am going to just that. I am in the process rehashing my setup, the only problem is that with me there are so many choices to make and pedals to build and the number of hours in a day. I would have to move to alaska in order to have enough daylight. But I am closing in on choices. I had to take time to absorb some learning curve on cmos switches but it  is coming together....the effects loop on my fender 185 is one of the best that I have heard, that in it self deserves to be taken out and traced and posted but here we go again. :idea:

[Kaiowas]

Once more, you've made some man's life easier!!

Thanks from Colombia!! thank you all!!

I think i'm gone modify the Alembic to put the FX Loop on it, i'll be studying some schems of other amps with FX Loop...if i find myself in a hole, i'll be here again, don't doubt it! (anyway i read some posts everyday)  

Take care, all of you!!