Ampeg SVT3 Pro PREAMP OUT Balanced or Unbalanced? NEED A DEFINITETIVE ANSWER QUICK!!!

[NKBassman]

My understanding is that it will have a low input/output sensitivity (voltage) compared to the Preamp out. The input sensitivity on the Crown is 1.4v the Ampeg DI output... unknown. Plus DI is usually a weak signal meant to feed into a PA MIXER. Yes it is balanced but I want to get the best balls out of this. *EDIT* Sorry but I also need to run DI to FOH along with cab.

If you're putting the bass into FOH then do you really need 1400W on stage?

I always found my old 3PRO to be more than adequate in a lot of VERY loud gigging situations.

In order to get the most out of the 3PRO, make sure you keep the Gain knob turned up so that the "Clip" light is flashing on every single note. On this amp, the Clip light is basically a signal indicator. If it's not lighting up, you're not getting everything the amp has to offer.

 

[two fingers]

OP - I have this square peg. I have ordered a round hole and before it gets here I need to know how to force the square peg into it.

Us - This is a really bad idea. There are tons of round and square pegs and round and square holes out there. Find a matching pair and put them together.

OP - Happy Holidays but shut up unless you know how I can jam a square peg into a round hole.

 

[okcrum]

Pretty sure over a long cable run that there will be enhanced noise rejection with the Rane connection beyond what is gained by the ground lift.

See this article. last page

FYI...The link opens to page 2 of the article which is the relevant part.

I believe these are equivalent circuits to our two adapters and a 30dB difference in rejection is claimed. The only difference is the shield is connected on both ends so there is no ground lift as suggested by Rane.

Enhanced, yes. I conceded you that point last page. As good as a properly terminated, balanced line, no. At least one end of the (transmission) line is terminated in some unknown impedance. There's no symmetry WRT ground in the system impedance because of the TS (one signal wire IS ground). You might get 30 dB with a perfect shield and perfect grounds on both ends. In reality what you'll get is a crap shoot. That difference in the shield hookup means a lot. Again, in this case, it's a 3-4 ft. run. I have to ask: What's your point?

Either of these hookups is IMO and IME a last resort. Any pro will put a transformer in at the unbalanced end and be done with it.

 

[NKBassman]

The 3 PRO is notorious for sounding quieter than it ought to. You have to max the master volume and slide that fader next to the EQ controls all the way up, then use gain to control your overall volume level.

IME this isn't the way to do it with the 3PRO. Set the Gain first so that the CLIP light is coming on strong on ever note. Then use the Master to set the volume where you want it. Use the Graphic EQ gain slider only if you need to... I never needed it playing in a metal band with two screaming guitars and a strongman power lifter for a drummer.

 

[fourstringburn]

Doesn't the Crown amp have a swichable input sensitivity switch?

Most amps have a 1.4v (+4dBu) and .775 (-10dV) switch meaning amp power can achieve full power when the input drive reaches optimum level. Using a mixer or output meters from a compressor or other device will show you this. Remember full power isn't regulated by the amps attenuators controls.

I have an SVP Pro preamp which appears to be similar to the SVT 3 amp. The XLR d.i. on my SVP is balanced but the output level is weak but can be stepped up by feeding it to a mixer channel.

This XLR out on yours may be too weak also to be driven straight to a power amp unless you use a .775 input sensitivity setting.

The preamp out on Ampeg amps and preamps are unbalanced. On my SVP preamps, the preamp outs are a stronger signal level and drive my external power amp just fine with a 1.4v setting. I do use a mixer and compressor to be sure the signal stays just under 0dB at a +4dBu mixer output level which ensures the power amp is at or near full power. The attenuators determine overall volume but not power.

Hope that helps some.

 

[BasturdBlaster]

The preamp out is 0.5v

 

[InhumanResource]

IME this isn't the way to do it with the 3PRO. Set the Gain first so that the CLIP light is coming on strong on ever note. Then use the Master to set the volume where you want it. Use the Graphic EQ gain slider only if you need to... I never needed it playing in a metal band with two screaming guitars and a strongman power lifter for a drummer.

This is pretty much what I do with my 6-PRO, but I was doing that because it is such a hefty power amp. If it works for the 3 then it's perfect.

I agree that this amp should have plenty of muscle but missed what OP's cab situation is.

 

[Jazz Ad]

IME this isn't the way to do it with the 3PRO. Set the Gain first so that the CLIP light is coming on strong on ever note. Then use the Master to set the volume where you want it.

I agree. The 3-Pro issue is with users afraid of blinking gain lights, not with a lack of volume.
It has a rather extraordinary preamp, which is one of the reasons it has sold well for 25 years with bare modifications.

 

[NKBassman]

I agree. The 3-Pro issue is with users afraid of blinking gain lights, not with a lack of volume.
It has a rather extraordinary preamp, which is one of the reasons it has sold well for 25 years with bare modifications.

It's certainly a solid amp that treated me far better than I treated it over years of abuse. I miss it, some days. I think having that flashing gain light labeled "CLIP" is the crux of the problem. If it were labeled "SIGNAL" that would be more appropriate.

Best solution: Put a piece of black electrical tape over the light and use your ears. Just turn the knob till it sounds the way you want it.


@BassYerFaceoff : I never used the Preamp Out, so sorry I can't answer your actual question. For Power Amp In connections from an external preamp (Sansamp) to the 3PRO I always used 1/4" TS cable and it worked fine. I realize this probably isn't helpful. Merry Christmas.

 

[NickFromNY]

I have the same Crown xls 1002 (and also the 1502) and the input sensitivity is switchable to .775v. That is how I run mine, bridged mono, into either a berg cn410 4 ohm cab or an Ampeg SVT 212-av 4 ohm cab. I have used an Ampeg SVP-Cl preamp, a PF350 and a GK MB200 to drive those power amps using both the preamp out and the xlr out. It can be done, and works well. I have gigged successfully many times. It does not pin the input monitor as far as signal goes, but it gets plenty loud. I posted something about it a while back. either the 1/4 or xlr will work

edit... i do run a Broughton HP/LP pedal between the preamp and power amp when using xlr and can boost the signal through the pedal.

 

[Deleted member 271037]

So between all the rude remarks it seems to be a matter or balancing the preamp out?

If the preamp has is a typical line output level/impedance perhaps one of these could help:

Invalid Link Removed

But I honestly don't understand the point of the extra power amp. Seems like a complicated way to accomplish something that may not even be a very wise thing to do.

 

[ctmullins]

The block diagram for the Ampeg implies that both the XLR and 1/4” Line Outputs are balanced. The Preamp Out is depicted with a TS connector, which would mean it’s unbalanced.

I would run the XLR balanced line out into the XLR input on the Crown, and use the Link/Out on the Crown to send to FOH.

I would also not run the Crown bridged. That’s too much juice for the cab.

Edit: In fact, I wouldn’t use the Crown at all. The SVT should be loud enough for stage volume on its own, especially if you’re sending DI to FOH. I’m not sure what problem you’re trying to solve here.

 

[InhumanResource]

So between all the rude remarks it seems to be a matter or balancing the preamp out?

If the preamp has is a typical line output level/impedance perhaps one of these could help:

Invalid Link Removed

But I honestly don't understand the point of the extra power amp. Seems like a complicated way to accomplish something that may not even be a very wise thing to do.

Exactly.

 

[InhumanResource]

The block diagram for the Ampeg implies that both the XLR and 1/4” Line Outputs are balanced. The Preamp Out is depicted with a TS connector, which would mean it’s unbalanced.

I would run the XLR balanced line out into the XLR input on the Crown, and use the Link/Out on the Crown to send to FOH.

I would also not run the Crown bridged. That’s too much juice for the cab.

Edit: In fact, I wouldn’t use the Crown at all. The SVT should be loud enough for stage volume on its own, especially if you’re sending DI to FOH. I’m not sure what problem you’re trying to solve here.

OP bowed out a while ago after refusing to describe the real issue is. Sounds like they just had a hard on to use a 1400 watt crown as a bass amp.

 

[NickFromNY]

I only use the crown when using my SVP-CL rack preamp, which is what I gig with most. I agree that the SVT-3pro should suffice in most situations. For smaller shows I have the PF350, and in an emergency, I have the MB200.

 

[pbassnut]

Ok, I have looked and searched everywhere I could think of and (unless I missed something) I cannot find a definitive answer. Yes I have looked at the manual and No it does not say. (Only mention is the DI)

The reason I'm needing to know is because I JUST ordered a Crown XTI 1002 (I plan on running in bridged mono) into a Schroeder 212pl 1200W rms using the SVT3PRO as a pre amp... I JUST realized that the CROWN has an imput impedence of 1.4v with BALANCED XLR inputs ONLY. *EDIT* Gig in TWO days! (Will receive on gig day!) Need to run my cab AND FOH using DI.

HELP.

If you're planning to use your SVT3 Pro as a preamp only, you might want to check with Ampeg technical support whether it's safe to run the amp without it being plugged into any speakers. Some amps can do it, but many can't and you could damage it if it's not designed to work that way. They could probably fill you in on the unbalanced / balanced issue as well.

 

[NKBassman]

If you're planning to use your SVT3 Pro as a preamp only, you might want to check with Ampeg technical support whether it's safe to run the amp without it being plugged into any speakers. Some amps can do it, but many can't and you could damage it if it's not designed to work that way. They could probably fill you in on the unbalanced / balanced issue as well.

Yes, it's fine in this case.

 

[Ric5]

I prefer to mike a cab with an SM 57

When I can't do that a balanced line out will do … a Crown power Amp should be able to take a balanced line out from an Ampeg …

The unbalanced line out can result in buzzing

 

[NKBassman]

*EDIT* Gig in TWO days! (Will receive on gig day!) Need to run my cab AND FOH using DI.

I just noticed this part of the OP. Running an untested high powered rig for the very first time at a gig seems like an exceptionally bad idea.

 

[agedhorse]

OP - One way to do this would be to use the DI out of your SVT3-Pro into the crown. Speaker out of the crown to input of a Palmer PDI. Out of Palmer PDI to input of your cabinet. The palmer then sends a line to your FOH. This way you'd have the balanced input for the crown with a different signal going to FOH. I do this currently with an Ampeg PF-50T, and have done it also with a V4B and an SVT. The palmer is not cheap, but sounds ridiculously awesome with a speaker connected after it. Might not be viable for your upcoming gig, but you could do it for the next one.

Good luck.

NEVER run the speaker output of a bridged amp into a DI. The pin 1 connection is tied to the 1/4" jack's sleeve terminal and will short the driven minus signal directly to console ground. This can damage the amp, the console, or both.

So between all the rude remarks it seems to be a matter or balancing the preamp out?

If the preamp has is a typical line output level/impedance perhaps one of these could help:

Invalid Link Removed .

This isn't going to help in this situation, it's a 1:1 ratio transformer that's intended for isolation only. It's not going to do anything for level matching.

The block diagram for the Ampeg implies that both the XLR and 1/4” Line Outputs are balanced. The Preamp Out is depicted with a TS connector, which would mean it’s unbalanced.

I would run the XLR balanced line out into the XLR input on the Crown, and use the Link/Out on the Crown to send to FOH.

I would also not run the Crown bridged. That’s too much juice for the cab.

Edit: In fact, I wouldn’t use the Crown at all. The SVT should be loud enough for stage volume on its own, especially if you’re sending DI to FOH. I’m not sure what problem you’re trying to solve here.

This isn't going to work because the balanced out is quite a bit less than the line level that the amp's input was designed for.

[edited for totally messed up formatting]