Tremoverb experts.....FX loop suckage normal?

[rpurdue]

Hey all. i have a 94 Tremoverb. It's retubed completely with JJ tubes. Sounds KILLER but.....Recently i've been getting into more delays and i notice a huge change in the tone when i switch the knob on the back to the effects loop. This is even with only a short patch cable between the send and return. I have the send maxed but manipulating the levels makes no difference. There's a huge loss in bottom end and more harshness introduced. Is this a normal occurrence? I replaced all the tubes with the correct ones including the one for the loop.

 

[elvis]

The search function is your friend.

"Tone suck" is a myth. You have a combination of:

1. Loop not 100% series. The latency of digital effects (time delay for A/D and D/A conversion and numerical processing) causes the dry signal to be mixed out of phase, which creates a comb filter that causes destructive interference of low frequencies and flanger-like effects in the midrange. This can be reduced somewhat, but there will always be a bit of feed-forward around the loop in the amp. It is an amp design issue, not an effects issue. Using analog-only effects helps, as there is no latency, but the quality is often poor with analog effects. If you're only using delays in the loop, set the delay box to "kill dry" or "100% wet" and dial the amp's FX loop to 50% wet (or whatever you like). For other effects you have fewer options.

2. Impedance mismatch. The output impedance of the FX send is high, and many FX boxes have quite low input impedance. This creates a filter that also reduces low frequencies. A good buffer between FX send and the FX input helps a lot.

 

[TremoJem]

Elvis,

Thanks for clearing this up. I had the same issue and even though I modded my two Tremoverbs FXLoops to Series from Parallel, I also added a buffer to each one of them between the FXSend of the amp and the FX in of the effect box.

This helps.

Some people thought I was crazy...I now feel better.

By the way I purchased two "This1sMine" buffers.

Just google it and you will find it.

 

[rpurdue]

The issue is that it does this without any effects even. If i just jump the send and return with a monster cable patch cord and turn the effects loop off and on via the back knob there is still a huge difference in tone. Would the series mod get rid of this?

 

[Nitrobattery]

The issue is that it does this without any effects even. If i just jump the send and return with a monster cable patch cord and turn the effects loop off and on via the back knob there is still a huge difference in tone. Would the series mod get rid of this?

+1

As much as I love my Tremoverb, I'm ready to ditch it because of the loop. Just engaging the loop sucks out a ton of bottom end and roundness.

 

[94Tremoverb]

Why are you maxing the send level? That will probably make the loop circuit distort, which could be part of the problem.

Either - do what it says in the manual and start with the Loop Active Master at noon, and adjust the send level to give unity gain; - or go even further and max the LAM completely, then set the send for unity gain. (No change in level when hard-bypassing the loop with the switch on the back.) This should put the send level somewhere around 9 or 10 o'clock.

I don't have any problems with the loop on mine, in fact it's one of the things I like about the amp compared to most others I've used. I've left it parallel. Changing it to series will help if the issue is caused by digital latency in the FX unit, but won't make any difference if you're still having trouble just with the loop jumpered.

I would also try different tubes than JJs. Personal preference admittedly but I really think they sound poor. I would certainly never want to use all-JJ in a Tremoverb.

 

[elvis]

Yup, in rereading your post I see that you were pretty clear about just using a jumper cable. My bad.

The FX circuit in the TVerb is interesting in that it completely bypasses the FX send drive and receive circuit (V4a&b, and associated circuitry). It seems possible that the settings of the loop active master and FX send controls could affect the tone, as it alters the impedance of the stages. Also, the tone of V4 would directly affect the FX circuit tone.

Try setting the knobs to nominal and swap V4.

Also, when using a patch cable from send to return, the FX MIX control should do NOTHING. See if that's true for your amp.

As with most of Mesa's circuits, it is all high-impedance, and uses a number of resistor-divides along the way, both for protection from external connection faults and to keep the voltages from hurting the user. That makes it reasonably safe, but it doesn't play well with many FX boxes.

I find it ironic that they went through the trouble of making the FX send a cathode-follower (a decent drive circuit with 600 Ohms output impedance) and then add a 25k FX send pot that increases the output impedance to several thousand Ohms at practical setting levels.

 

[TremoJem]

The search function is your friend.

"Tone suck" is a myth. You have a combination of:

1. Loop not 100% series. The latency of digital effects (time delay for A/D and D/A conversion and numerical processing) causes the dry signal to be mixed out of phase, which creates a comb filter that causes destructive interference of low frequencies and flanger-like effects in the midrange. This can be reduced somewhat, but there will always be a bit of feed-forward around the loop in the amp. It is an amp design issue, not an effects issue. Using analog-only effects helps, as there is no latency, but the quality is often poor with analog effects. If you're only using delays in the loop, set the delay box to "kill dry" or "100% wet" and dial the amp's FX loop to 50% wet (or whatever you like). For other effects you have fewer options.

2. Impedance mismatch. The output impedance of the FX send is high, and many FX boxes have quite low input impedance. This creates a filter that also reduces low frequencies. A good buffer between FX send and the FX input helps a lot.

I have a This 1s Mine buffer between the amp and TC GMajor.

Here is my question: When I press the FXLoop bypass foot switch I still see signal (on the gmajor meter on display) going thru or bleeding into the gmajor...no effects are audible as I guess it prevents it from reaching the amp.

Without much of an engineering background I would think this is because of a mismatch in the buffer, or that the buffer is too strong?

I worked with Dan to customize it by sending him the specs for the Tremoverb and the GMajor, as I suspected that 10M was not a good buffer compared to 1M. He assured me that I would be happy.

I will say that all sounds good, but am just wondering what your opinion was. Thanks Brother.

 

[screamingdaisy]

Here is my question: When I press the FXLoop bypass foot switch I still see signal (on the gmajor meter on display) going thru or bleeding into the gmajor...no effects are audible as I guess it prevents it from reaching the amp.

The amp mutes the FX return while still allowing signal to pass out send, which is useful for multi amp setups where the FX are slaved into a second amp.

 

[TremoJem]

Here is my question: When I press the FXLoop bypass foot switch I still see signal (on the gmajor meter on display) going thru or bleeding into the gmajor...no effects are audible as I guess it prevents it from reaching the amp.

The amp mutes the FX return while still allowing signal to pass out send, which is useful for multi amp setups where the FX are slaved into a second amp.

So I guess this is normal, whereas before I used the buffers I never saw this bleed.

So nothing to worry about huh?

Thanks man...