Why can't I make my Triaxis work with the DC3 power amp?

[Gerax]

Hi all

I'm trying to put together the various pieces of gear I've collected in the years in an organic and flexible setup.
I mainly have Mesa amps, a Triaxis and a DC3 combo (whose electronics I'll be fitting in a custom built short head cabinet for rackmount purpose) which I'd double with a second one to use the 2 preamps and power amps as separate sections: this way I'd have 4 different sounds from the preamps and a stereo power section. I'd accomplish this with a GCX switcher and a stereo line mixer for parallel FX and stereo routing to the power section.

Now, I'm doing some connection tests before assembling the rack (and getting the second DC) and I found that if I plug the Triaxis straight in the FX return of the DC I get a muffled, dark sound no matter how I set the controls on the Triaxis; also, Triaxis' volume doesn't work, I either get a very low level (at 1 on the volume pot) or a notch above but it stays the same even if I turn it up way loud.
FX level on the DC is 100% wet, and if I do a standard connection with an FX unit (I tried with an Eventide Eclipse) the loop works fine and the combo plays and sounds fine.
I should also say that the DC FX loop is parallel, but the manual says that if the control is set to 100% wet the amp can be used as a plain power section.

I also tried to plug the Triaxis in the front end input of the DC and it looks like evrything is working as it should: I get all of my standard preset sounds and volume output works fine too.

Next I'll ty to plug the Triaxis in a regular power amp (i'll have a VHT 50.2.50 at hand tomorrow) and see if it works OK.

In the meantime, any ideas on why I'm getting this strange behaviour? Should I modify the FX loop to serial? any Impedance issues I should be aware of?

Thanx

 

[geetar_geek79]

im not familiar with the dc at all, but some amps need to have something plugged in the send jack for the return jack to be active. heck, some amps even require something plugged in the input jack for the effects return to work - like my vetta. but that's another story.

 

[bhsbhswarp]

make sure your using the main out of the triaxis.Also you want to turn the GEQ to off.If it'sa older DC you may need to clean the jacks up.Also modding the fx loop would be easy to do.My loop works well with my modelers.(serial mod)

 

[Gerax]

Hi,

Thanx for the reply.

According to the DC schematics it looks like it there actually has to be a jack plugged into the Send socket for the FX loop to work properly as it's been said above; this is due to the fact that the send jack also acts as an "on switch" for the circuit that otherwise works in an awkward way if only the half part of it is used...

Easily cured...I'll do some tests this evening. It also comes as a bonus as I want to switch between the DC's preamp and the Triaxis in my rig, so the Send Jack is also going to be used.

Thanx for you time and support.

L.G.

 

[bhsbhswarp]

cool,mine was conveted to serial loop before I bought it,so mine does'nt have that issue.Hope it all works out,sounds to be a cool setup.

 

[Gerax]

I hope I'll find a second DC3 as I'm going to convert the combos to short heads and rackmount them; then I'll be switching between the 2 DC preamps (so that's 4 sounds) the graphic EQ (another sound) and the Triaxis presets...should be pretty versatile as far as tones go; I'm tossing in an overdrive/distortion pedal too for a different more Marshall type flavor, from there it goes to line mixer and FX (Eventide and Lexicon), and finally I'll have a looper for additional fun! The FX return on the DCs will act as a power amp in for stereo setup to 2 2X12.

 

[MJ Slaughter]

Gerax, I so glad you started this thread. I too have wondered way my preamps/amp modelers sounded dark and muffled in the loop return only of my DC amps which have been turned to serial loops. geetar_geek79's comment about having a jack in the send caused me to try that, and it works great now. Just slap a 1/4" in the send and you should be good.

If you're interested, there is a DC3 head for sale in my area by someone who I think is a member here. For some reason I think I've seen his ad on this forum. Here is the Craig's List link: http://dallas.craigslist.org/ndf/msg/2452621564.html

 

[geetar_geek79]

Gerax, I so glad you started this thread. I too have wondered way my preamps/amp modelers sounded dark and muffled in the loop return only of my DC amps which have been turned to serial loops. geetar_geek79's comment about having a jack in the send caused me to try that, and it works great now. Just slap a 1/4" in the send and you should be good.

If you're interested, there is a DC3 head for sale in my area by someone who I think is a member here. For some reason I think I've seen his ad on this forum. Here is the Craig's List link: http://dallas.craigslist.org/ndf/msg/2452621564.html

glad it worked out for you...

 

[Gerax]

OK, so I actually did the test and yes, IT WORKS! According to the DC 3 schematics if the send jack isn't plugged in the loop isn't closed and the result is a feedback loop of the signal onto itself that causes the anomaly in the tone.

Now it works and I get all my standard clean and distorted presets sounding as they should, but the power amp section overdrives very easily even with a clean preamp setting if I turn the output volume of the Triaxis up to a normal usage level (say from 3 to 5). I guess the output from the preamp is quite hot so that it drives the power amp section into distortion even a pretty low volumes, and I was wondering if there's a way, like a passive attenuator, pad or something like that, to bring it to a more manageable level and allow to use the volume control to its full range.

Thanx

 

[Gerax]

Bringing back this topic to ask a question:

I've managed to have the TA work with the setup, but...It just doesn't sound right: I mean, it looks like the TA/DC3 power section isn't a good combination as all lead tones sound shrill and lack air and depth, clean tones sound small and not dynamic as I remember them. When I switch to the DC3 (using its preamp, I have everything hooked up to a GCX switcher) I get a solid, full bodied tone harmonically rich and complete.
I used to have the TA plugged into a 2:90...but I sold it (I loved it but it was too much power and too much weight for me...) and it sounded stellar...I wonder if pairing the TA to the DC3 section can make such a difference...I cannot get a satisfying tone out of it and I should know how to use both the amps as I have been using them for may years...

Opinions?

 

[eet fuk]

3rd year, 3rd consecutive post! :lol:

I've been wondering about hooking up a pre to a boogie myself, and this dc with graphic comes to mind.

In your situation I'm thinking out-of-phase comb filtering. Small signal level produced by the plug in the fx send jack mixed (says 100%, but maybe in reality like 90%?) with the triaxis 5 stage signal that's out of phase with signal (each stage flips the phase)? If so, maybe you could flip the wires in the end of the cable going out of the triaxis into the return, and that would bring it back to normal. Or the serial mod.

It's been a year after the OP posted. If you're not around, anyone else mess with this and find the same problem and hopefully a solution?

 

[talltxguy]

The DC-3 output section uses EL-84's, which don't have much headroom. And then you have the fact that DC-3s run their output tubes at nearly 160% max plate dissipation, and you have even less headroom. So I can only speculate that the DC-3 output section is mushing your tone. I would try to find the coldest EL84s possible and put them in your amp.

Also, try using an 12AT7 in the phase inverter of the DC-3 as well as an 12AT7 in V3 (FX return) as I believe this will provide more headroom than 12AX7s.

I have never tried running a preamp into the DC-3, so my two cents may be worth crap. Hope this helps you out though.