Sansamp psa-1 with blender pedal in SVT-4 effect loop?

[permadave]

Hello All,
I like the way my psa-1 sounds in the effects loop of my svt-4 but would like to mix in some dry signal. Would the Barge VFB-2 setup in the following config get me where i'm going? Would the vfb-2 work right with a line level input from an amp effects loop like I'm thinking of doing? Any different suggestions to blend dry signal in?
This is how I think that it would be set up:


1. send from SVT-4 effects loop to vfb-2 input

2. vfb-2 SEND to the sansamp input (it has line or instrument level selector {0 vs -10db}, I'm assuming it would need instrument level, right? (-10db))

3. sansamp output to the vfb-2 RECEIVE

4. vfb-2 output to SVT-4 effects loop RETURN

I don't really like the PSA-1 in front of the amp as much as in the effects loop so any help with this would be appreciated.

Thanks!

[bongomania]

If you don't already have the Barge, be aware they fell off the face of the earth a couple years ago. Not officially "out of business", just AWOL.

I'd suggest either the Xotic X-Blender or the [sfx] X&M. The Xotic has a phase inversion switch that can sometimes make or break the quality and effectiveness of blending dirt signals with clean. The [sfx] uses a crossover, so phase problems are avoided by splitting the signal into two frequency ranges and processing them separately. Another option would be a Y-splitter from the fx loop send, and an FEA mixer at the other end going into the return. The FEA mixer has an excellent phase adjustment control.

[permadave]

thanks Bongomania! I think I might give the FEA Mixer a try. Sounds like it may work best for this application out of the available options. Do you think I'd have to have the gain set really low on the FEA for signal coming from the effects loop of the amp since it's line level? Do you think I'll be able to achieve a pretty good mix this way? I pretty much want to be at 70% Sansamp 30% dry. Thanks for all the help!

[bongomania]

I'll try my FEA mixer at line level sometime today, and report back on the results.

[permadave]

Originally Posted by bongomania

I'll try my FEA mixer at line level sometime today, and report back on the results.

Thanks man but it sounds like that may not be necessary. I wrote to FEA and this is what Frank had to say, who gave you a shout out by name lol.

Hello David,

The Mixer will operate with line level signals and should work fine for the application that you describe because of its 18V headroom. The only thing that you need to be aware of is that the channel gains of the mixer range from -5dB to +12dB. At -5dB the signal is approximately 1/2 level, so you would have to run the sansamp channel with a bit more than +6dB gain to achieve the ratio mix that you are looking for (30% dry 70% sansamp). I would think that your amps effects loop should handle the hotter signal just fine, though you may have to turn the amps master volume down a bit for your normal playing volume.

If you are interested in saving some money, there is/was a fellow (bongomania) on talkbass.com that has one of these mixers for sale.

Thank you for the interest in our products!

Best regards,
-Frank Appleton

[bongomania]

Remember you will still need a splitter to divide the loop send into the clean and PSA-1 channels.

[permadave]

Originally Posted by bongomania

Remember you will still need a splitter to divide the loop send into the clean and PSA-1 channels.

I'm assuming I can just pick up one of those cheap Y cable splitters at the Shack of Radios? I thought I had one but can't find it. I think it was only 5 bucks so no biggie. I wanna do this ASAP but I'm not sure I can justify the money till after xmas My Mesa M-pulse head does have a blend knob in the FX loop so maybe I'll just use it till then instead of the SVT. Thanks for the help, very much appreciated!

[tech21nyc]

You might consider running your bass into a splitter first and from there to the front end of your Ampeg and the other half of the split signal to the PSA. You could even use a stereo chorus pedal or something similar for this. Then you would need to run the effects send of your amp to an ABY box and the out of the PSA into the ABY box and the out of that to the effects return of your amp and use the controls on bothe units to blend as you wish. There a number of different ways to do this. Lehle makes some excellent products for this type of application. You would also to factor in possible ground loop problems. Lehle switchers have excellent isolation transformers.

[permadave]

Originally Posted by tech21nyc

You might consider running your bass into a splitter first and from there to the front end of your Ampeg and the other half of the split signal to the PSA. You could even use a stereo chorus pedal or something similar for this. Then you would need to run the effects send of your amp to an ABY box and the out of the PSA into the ABY box and the out of that to the effects return of your amp and use the controls on bothe units to blend as you wish. There a number of different ways to do this. Lehle makes some excellent products for this type of application. You would also to factor in possible ground loop problems. Lehle switchers have excellent isolation transformers.

Thanks for the help. It's awesome that you guys are on TB helping out your customers. In your scenario, where would the send on the SVT effects loop go, to the ABY input or output? Which ABY would it need to be? 2 in's and 2 outs or 1 in, 2 out's? Does this diagram look right?

[boomertech]

If you use isolated power supplies for the mixer and PSA, the possibility of ground loops will be minimal.

It looks like a blender box or the y-cable/mixer combo will be the simplest configuration for what you are looking to achieve. The only thing you would need to know is if the PSA inverts the signal from input to output. If the signal isn’t inverted then you can use a real cheap NADY 4-ch mixer for less than a set of strings from MF or GC. If the signal is inverted from the PSA then you will need something with a phase switch or control to avoid the phase problems that bongo mentioned.

-Frank

[bongomania]

Originally Posted by permadave

where would the send on the SVT effects loop go, to the ABY input or output? Which ABY would it need to be? 2 in's and 2 outs or 1 in, 2 out's?

In his suggested approach, you would need an ABY with 2 ins and 1 out; note that most ABY boxes are just passive switches, so they work both ways (2-->1 and 1-->2). It goes like this:

bass --> splitter
splitter output 1 --> Amp instrument input
splitter output 2 --> PSA input
Amp fx loop send --> ABY input "A"
PSA main 1/4" output --> ABY input "B"
ABY output --> Amp fx loop return

It's a clever system, but it may be vulnerable to feedback.

[permadave]

Originally Posted by boomertech

The only thing you would need to know is if the PSA inverts the signal from input to output. If the signal isn’t inverted then you can use a real cheap NADY 4-ch mixer for less than a set of strings from MF or GC. If the signal is inverted from the PSA then you will need something with a phase switch or control to avoid the phase problems that bongo mentioned.

-Frank

Hopefully Tech-21 will chime back in on this point, thanks Frank!

[tech21nyc]

Our PSA is phase coherent. There is one problem with all of this that our engineer pointed out to me. Even though the PSA is phase coherent as I'm sure your Ampeg is in phase as well there will be a phase "shift" whenever you adjust the EQ on either unit. It won't be a 180 degree shift but there will be a shift to a certain degree. He really recommends using a mixer to combine the 2 signals. It would probably be best to temporarily try it before purchasing anything fancy to see if it is worthwhile for you.

I think you will get a better sound out of the PSA by having your bass plugged into it rather than having your Ampeg's preamp circuitry driving it. Perhaps a better alternative would be to use a splitter or any mono in stereo out stompbox to send your bass signal to the inputs of your Ampeg and to the PSA and from there send the efx send of your Ampeg and the out of the PSA to an ABY to your amps efx return and you have 2 different sounds. There are a number of different configurations you could try it really depends on what sounds you are trying to achieve.

Without being there it's hard for me to tell but it sounds like you are using the PSA to add some tube grind to your sound. Have you tried just bypassing your Ampeg's pre entirely and just going through the PSA into your Ampeg's efx return?

[permadave]

Originally Posted by tech21nyc

Our PSA is phase coherent. There is one problem with all of this that our engineer pointed out to me. Even though the PSA is phase coherent as I'm sure your Ampeg is in phase as well there will be a phase "shift" whenever you adjust the EQ on either unit. It won't be a 180 degree shift but there will be a shift to a certain degree. He really recommends using a mixer to combine the 2 signals. It would probably be best to temporarily try it before purchasing anything fancy to see if it is worthwhile for you.

I think you will get a better sound out of the PSA by having your bass plugged into it rather than having your Ampeg's preamp circuitry driving it. Perhaps a better alternative would be to use a splitter or any mono in stereo out stompbox to send your bass signal to the inputs of your Ampeg and to the PSA and from there send the efx send of your Ampeg and the out of the PSA to an ABY to your amps efx return and you have 2 different sounds. There are a number of different configurations you could try it really depends on what sounds you are trying to achieve.

Without being there it's hard for me to tell but it sounds like you are using the PSA to add some tube grind to your sound. Have you tried just bypassing your Ampeg's pre entirely and just going through the PSA into your Ampeg's efx return?

Thanks for all the help and yes, I am just trying to add a little grind to my signal to dirty it up. Specifically I want a mix of my post-eq amp signal and the sansamp outpt. I would prefer if the Sansamp received a pre-eq signal but it doesn't sound too bad to me with a post eq signal and I can live with that. I'm not really running extreme eq settings so that's probably why it sounds ok. I'm using a typical "frowny face" eq config for a slight mid boost. The sansamp works this way okay with my Mesa Mpulse, running in the effects loop (mesa has a blend knob for the effects loop but the Ampeg doesn't) but I can definitely see an advantage to having the sansamp get a pre-eq signal.

To answer your other quesion I have tried bypassing the apmpeg's pre by just turning it off on the front of the amp while the PSA is in the effects loop and have also tried using the PSA as a preamp straight into the poweramp section of the Ampeg. Also I have tried just running it in front of the amp like an effects pedal.

As for splitter for the bass signal I don't have any stereo effects pedals laying around unfortunately. Would a regular Y cable work ok? I have heard in the past that those don't work that great with instrument level signals. I used to use one in the past to send my bass signal to both inputs on a Mesa 400+ head and it seemed to work ok though.

Thanks!

[boomertech]

A y-cable should be fine for feeding two inputs.

-Frank

[tech21nyc]

Originally Posted by permadave

Thanks for all the help and yes, I am just trying to add a little grind to my signal to dirty it up. Specifically I want a mix of my post-eq amp signal and the sansamp outpt. I would prefer if the Sansamp received a pre-eq signal but it doesn't sound too bad to me with a post eq signal and I can live with that. I'm not really running extreme eq settings so that's probably why it sounds ok. I'm using a typical "frowny face" eq config for a slight mid boost. The sansamp works this way okay with my Mesa Mpulse, running in the effects loop (mesa has a blend knob for the effects loop but the Ampeg doesn't) but I can definitely see an advantage to having the sansamp get a pre-eq signal.

To answer your other quesion I have tried bypassing the apmpeg's pre by just turning it off on the front of the amp while the PSA is in the effects loop and have also tried using the PSA as a preamp straight into the poweramp section of the Ampeg. Also I have tried just running it in front of the amp like an effects pedal.

As for splitter for the bass signal I don't have any stereo effects pedals laying around unfortunately. Would a regular Y cable work ok? I have heard in the past that those don't work that great with instrument level signals. I used to use one in the past to send my bass signal to both inputs on a Mesa 400+ head and it seemed to work ok though.

Thanks!

Using the Y cable depends upon whether your bass is passive of active. It will work either way but with a passive bass your signal will be loaded down somewhat as it is not low impedance. Just for the sake of trying it I would give it a go. If you like using the PSA after your Ampeg's preamp out that is fine too but in general running two preamps in this manner is not the best approach. It's still best to use some sort of mixer to combine the sounds of both your Ampeg's pre and the PSA.

It sounds like it may be cheaper in the long run to consider perhaps using either our SansAmp Paradriver DI or Bass Driver DI for what you are trying to accomplish. You can get there with the PSA as well but by time you purchase a splitter and a mixer it may turn out to be more economical to just use one of the aforementioned pedals.

[bongomania]

Originally Posted by tech21nyc

It sounds like it may be cheaper in the long run to consider perhaps using either our SansAmp Paradriver DI or Bass Driver DI for what you are trying to accomplish. You can get there with the PSA as well but by time you purchase a splitter and a mixer it may turn out to be more economical to just use one of the aforementioned pedals.

Totally!

[permadave]

Originally Posted by tech21nyc

It sounds like it may be cheaper in the long run to consider perhaps using either our SansAmp Paradriver DI or Bass Driver DI for what you are trying to accomplish. You can get there with the PSA as well but by time you purchase a splitter and a mixer it may turn out to be more economical to just use one of the aforementioned pedals.

Agreed! I was just hoping initially to use the PSA since I already own one for guitar. Thanks all.