Is Buffer required to split dry FX Send?

[Throb]

Want to bring my TriAixis pre-amp's  parallel effect loop scheme out of the stone ages. Been using Y chords to connect 2 mono in / stereo out analog modulators (HT Delay + BOSS CE 300).

A small budget project, so I acquired a Behringer MX-882 (PDF) mixer / splitter to combine the stereo outs and route them to the TriAxis A/B FX return ports. Was going to get a blank effects box to build a splitter, but after checking shipping costs out, decided on a Galaxy JIB S 4-way Splitter from Sweetwater.

Talked with a Mesa tech and he suggested I might need a buffered splitter.

At most, I'll only run 3 modulators in the TA Effect Loop. Question Does the splitter need a "buffer"? If so, could the JIB S be modified by adding a buffer? Would appreciate any links (i can recognize ground, resister, and capacitor symbols, but couldn't tell ya where a pre-amp or feedback loop is in a schematic). Can solder cables and connectors and small mods to my effects - still a rookie.

Might need a new thread for this. Trying to figure out a bypass scheme. One modulator is racked, the other is not. Right now it seems the only way to properly bypass, would be between the FX Out and the Effect return ports. The switch would need to break the wet path and insert a dry signal.

Thanks.

[chptunes]

I can't say if you do or do not need a Buffered Splitter, but if you decide to build one:  http://www.muzique.com/lab/splitter.htm

-Corey

[slacker]

If you're currently connecting the FX send to two units using a Y splitter and that works then adding a third will probably work as well.
Have you got a link to a schematic of the amp? I had a quick look but I couldn't find one that showed the FX send, with that we might have a better idea of whether you need a buffer.

[Throb]

Thanks Slacker,
This schematic isolates on the I/O (back panel?) stages.

This, I believe, is the entire schematic set for the TriAxis (including) MIDI CB.

JIC: The TriAxis Manual (PDF).

According to Tubefreak, this is the the signal path:

INPUT -> (V1) -> V2A -> EQ -> V2B -> (V4) -> V3A -> PRESENCE -> VOLUME -> TL072A -> DYNAMIC VOICE -> TL072B -> (FX SEND) -> (FX RETURN) -> V5A + V5B -> MASTER VOLUME -> OUTPUT

TL072B is shown in the upper right section of the first link (or 3rd schema down in the second link).

[Throb]

I can't say if you do or do not need a Buffered Splitter, but if you decide to build one:  http://www.muzique.com/lab/splitter.htm

Corey
Thanks for the link - I especially liked the little PCB image at the bottom with the parts listed.

[slacker]

Cheers for the schematic links, I think you'll be fine without a buffer, the opamp driving the send should be perfectly happy with 3 things attached to it. The worst that can happen is you might get some volume loss but you can compensate for that with the mixer.

[Throb]

Slacker,

Thanks,

Analog Stereo Parallel Effect Loops with mono in stereo out FX devices is a career path I had hoped to avoid. Really appreciate you guys helping on this.

The MX 882 (PDF)seems allow allow channels to be [concurrently] designated as mixing or amp matching. The manual is not "obviously" specific (to urs tru) regarding the "amp matching" feature as it relates to the main outs for the mix channels. zZSounds support tech looked at the amp matching schema and opined along with urs tru that engaging an XLR in the channel output disengages channel output to the main, or mixed, outputs - but wisely reluctant to offer a firm response.

Filed a Behringer support request for clarification. Should channels configured as "amp match" (or fx input buffering) channels when their output jack is engaged NOT bleed into the mix-out, it should be easy to sort the "buffer" or "not to buffer" the split effect send signal thingamabob.

Also trying to figure out how to implement bypass. Engineers never let me around their boards. Curious as to what happens to the mixed main out if an active channel input is disengaged. Do the remaining connected/engaged input channels re-sum up to main output levels, or is the mix output diminished? What happens to the mixed output when a channel's input device is disconnected?

Also curious, while I got you on the line, as to how many db's does a return stage need to "hear" to maintain nominal performance?

If the effect loop return stage is happy with a next to nothing (db wise) dry signal, could [possibly] use the MX 882's main input stage to parse a low level dry signal to the main outs. That way, to this rookies noodle, if the input source for all the mix inputs are disconnected, the TA's effect loop return might be satisfied with the low level dry drone sig from the main inputs: Meaning: The bypass switches would only need to be ON/OFF gizmos whose only concern is passing, or blocking, the line inputs. And not worry about the dry guy!

If it don't work, then the only thing that comes to mind would be to hook relay up to each bypass switch. When the switch is set off (disconnects the input source or effect loop send), the relay would bridge a drone dry signal path. In a case where all the bypasses were bypassing, all the relays would bridge the alternate drone dry signal to the effect loop return stage.

Question is, is totally "min" level dry signal an acceptable dry signal.

So much to learn - and all I wanna do is work this amp and thrash phat inverted fifths - or fourths - or augmented 7th / diminished 9th collages  - or any tone that slays the demon !

QFTD - Does gasoline cost more because it is worth it, or does gasoline cost more because the dollars we trade for it are worth less?