PS2A big volume differences between Synergy preamp and main amp

[cdonat]

I don’t yet know, which component is the issue, but since Fryette is also involved in Synergy I hope to get help here.

I run my guitar into a Synergy Syn1. The Syn1 Bypass is connected to a Vox AC30. The Vox’ output is connected to the PS2A, and the PS2As FX loop in return is connected to the Syn1s Amp FX loop connections, since vintage AC30ies don’t have FX loops.

When I run the Syn1 the resulting signal is reasonably loud, but when I bypass the Syn1, the Voxes signal gets out very silent. The Vox is canked, and I’ve experimented with several combinations of FX loop levels, PS2A line level, and input level. Some settings made things worse, but none improved the issue.

I’ve also experimented with other amps, from 15W to 100W, and I’ve tried using the amps FX loop, where possible, as well as the PS2A FX loop. It’s always the same issue, just on slightly different levels.

Can anyone please point me to what I might be missing. I had everything working fine, before I decided to restructure my studio. Therefore I assume, that the devices are OK, adn I messed something up.

[Gil]

Hello, I’m hoping to help you out here but I need to know some more details about how you configure your rig. Please tell me what output on the SYN1 you are using to feed the Vox AC30?

Have you tried connecting the Vox amp to the PS-2A without the SYN1 connected just to see if the amp and PS-2A play together nicely? I’ll wait for your answers to these questions before attempting to assess the other issues. Thanks! Gil

[cdonat]

Thank you very much for trying to help. The “To Amp In” is connected to the AC30. To make it complete, the PS2A FX loop is connected to “From Amp FX Send” and “To Amp FX Return”. “Main out” is not connected.

The Vox seems to get the normal signal to its input, since it’s overdrive sounds as usual. Therefore I guess, the issue is after the amp. Either in the load, or with the PS2A FX loop.

I haven’t tried without the Syn1. That’s a good idea, and shoud give more information. ATM it’s late at night over here, so I’ll try tomorrow.

[cdonat]

I’ve tried without the Synergy now. The level is still very low.

• the PS2A’s FX loop is plugged in, but bridged directly. It just was easier without ripping everything apart again.
• the guitar goes directly into the AC30, I haven’t checked again with the other amps, but since the behavior was the same for all amps with the Synergy, it’s probably not the amp.
• the input level on the PS2A is on “Low”. I’ve even tried with “High” but unsurprisingly that resulted in an even lower output level.

Of course now I can’t compare directly with the output level with the Synergy. But I had to put the PS2As volume as high up as before with the Synergy-bypass.

So I guess, that takes the Synergy out of the equation now. I can’t think of any cable plugged in wrongly, that would still give some output. Also I don’t think, there’s an issue with the PS2As power amp, because it’s as loud as expected, when driven from the Synergy in the FX loop.

[Gil]

Thanks for the additional info and details. I have a couple more questions; are you connecting your Vox AC30 with its internal speakers like this;

In what manner are you “bridging” the PS-2A’s FX loop? That seems to be a variable here that we can’t be absolutely sure about unless you physically disconnect the loop from any other components. I know it may be a pain to undo your rig, but if we determine that your PS-2A needs service, you’ll have to remove it anyway. Please let me know. Thanks! Gil

[cdonat]

Yes, that is exactly, how the speakers are connected.

The “bridging” of the FX loop means, that there’s a direct connection.

The complicated explanation is, that the FX loop is connected to a KHE amp switcher, which also switches FX loops. It has a switch, with which I can directly connect send and returns, instead of sending them to the Synergy FX loop. THat is how I checked without the FX loop this morning. As I said, unplugging the FX loop involves dismantling quite some of my setup.

Anyway, I’ve just crawled behind the rack, and pulled the FX loop from the PS2A. Still the same.

I don’t think, it’s the PS2As power amp, because it has no issue to amplify the Synergy signal. I also don’t think, it’s the Amp, because using it stand alone is really, really loud, as it should be. My best guess is, that it’s the PS2As load, or one of the connections.

I still don’t exclude the option, that I’ve plugged in something wrongly, because exactly that setup worked, before I moved things around in the studio. Breaking the load part of the PS2A, which probably is the least sensitive part of the whole device, just at the moment, when I rebuild everything, is not impossible, but the probability seems pretty low to me.

I just can’t think of anything in the cabling, that would produce this specific result.

[DavidPhelge]

There is a level switch on the back Syn that sets the levels of the external amp send and return jacks on the Syn. There is a corresponding rear panel FX level switch on the PS-2 that does the same thing.

You just need to try each position of each switch to see which combination yields the best volume balance.

I recommend keeping the volume down on the Syn and the PS-2 when changing these switch settings.

Dave

[cdonat]

Thank you for your response. I’ve tried all possible combinations of these level switches.

The volume balance is not the main issue. Well in a way it is, but the low level of the signal captured from the amp is strange. I shouldn’t have to turn the PS2As volume to 3 o’clock, just to merely get to bedroom level from a cranked AC30. And I didn’t have to before moving stuff around in my studio.

There’s only one combination of the two level switches, where at least the Syn produces a reasonable output level around 9 o’clock. Yet the AC30 doesn’t.

I have the same effect with a 15W Orange, and a newer AC30 - both of them cranked, and an old 100W solid state amp - at 70%-80% level. Those have FX loops, and when I use that, instead of the PS2As, the level is always very low, even with the Syn. That’s expected, because then the Syn signal also goes through the amp power amp, and the amp input of the PS2A.

[cdonat]

And just a few minutes after my last post I have found the root cause: the cable from the KHE amp-switcher to the PS2As “Amp In” was broken. I found that by accidentally touching it. Replaced the cable and everything works, just as it should.

Thanks again to everyone who chimed in, trying to help. Maybe I should have tried to wiggle all the cables, before panicking.

[Gil]

Happy to hear that you found that faulty cable. The clue was that everything was working fine until you moved things around. This is a good lesson for all of us to remember to check all connections no matter what. That’s a big part of what this forum is all about. Cheers! Gil