effects loop install question

[12AX7]

I have a little combo i built a long time ago thats basically a jcm 800 master volume style build tho with a 6v6 output section and18 watt transformers. I need to put a loop in it but i don't want to spend any big time energy or money on it because it;s just an amp i use now and then and this isn't real important. Tho what IS important if i can possibly do it without all the time/money is i don't want to kill the tone. I was thinking of just using a pair of jacks, one switching of course, and sticking them between the master and PI. The effects i would be using is a small 1/2 rack DSP that has its own in and out levels.  Question is, if the levels are adjusted optimally on the DSP, will that kind of loop sound as good as a active one? I realize the DSP itself will degrade the signal to some degree depending on how well designed it is.

I guess what i'm asking in a concise form is, with all else being equal, IE: using the same DSP and proper in and out levels on it to match the particular loop, will this loop work as well as an active one? Seems to me active loops are considered better because you can match in/out levels on effects that don't have them so you don't overdrive the input and/or have too low an output. Is that it or are there other reasons a passive simple will degreade tone?

[kagliostro]

I HIGHLY doubt that the output level of the effect can match the level requested by the PI

Franco

[burger]

Can work.  I had a passive interrupt loop on a plexi style amp.  The loop was an serial interrupt style sitting in between the master volume and entry to the PI.

Work fine as long as you have a effect that can handle a fairly hot signal without the need to pad it down.  Also long cable runs won't work, you'll need a buffered loop to run long cables back and forward to a pedal board.

[12AX7]

Thanks, it wouldn't be running to a pedal board, i'd be using a 1/2 rack size DSP so it'll just sit on the amp. I don't think the input signal will be too hot because as long as the output is large enough to get the amp volume where i want it i can leave the master real lo to keep from OD'ing the unit. At least in theory that should be the case. Guess i'll try it today, thanks.

[tubenit]

As an FYI,  I have found an MXR carbon copy delay and a Boss Digital Delay DD-6 (?) to work just fine in passive delays.

I prefer an active effects loop because I use them as a type of master volume prior to the LTPI & I can tweak the higher frequencies a little bit, but really I've been pretty happy with those two delays in a passive FX loop.

With respect, Tubenit

[Ed_Chambley]

+1 on a simple passive loop.  I use a Boss EQ in front of modulation effects which gives me a level control and I can eq the pedals too.  I have a Delay, Chorus, Flanger, Reverb and tremolo on a little board that I run through a passive loop.  I have never had to boost the signal very much at all.

[12AX7]

I installed it and I'm more than happy with the result. Works prefect and very transparently with the my DSP. It has a +4/-20 DB switch so that along with input level courtesy of a front panel knob and software output level globally and per patch, theres no issue with levels at all. I was also quite surprised by the fact it's quiet too. In fact, the amp itself is a slop fest i threw together haphazardly yet sounds fabulous and quiet ! Makes me kinda wonder why i spend so much effort on other amps building them so clean. Anyways, thanks all. Loop successful....