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

BassYerFaceoff

BassYerFaceoff

Aug 23, 2018
131
169
DC Metro Area
#1
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.
 
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#3
two fingers said:
Maybe I'm missing something. What is preventing you from using the XLR from the SVT to go into the Crown?
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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.
 
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#4
Keep in mind, as I understand it, the tube gain section is AFTER the preamp. So you won't be getting that part in the preamp out. That 12ax7 and 12au7 (I think I'm right on the second one.... it's been a long time since I owned mine) are used to drive the power section (MOSFET maybe?). There are 2 or 3 more 12ax7 tubes in the preamp section.

So, to me, it won't really be the sound of the SVT III through the cabs running it into a power amp straight off the preamp. It'll sound fine. But it just won't have the grit you could get through cabs otherwise.

Keep in mind, I last owned one in the late 90s. So I could be remembering incorrectly.
 
#5
two fingers said:
Keep in mind, as I understand it, the tube gain section is AFTER the preamp. So you won't be getting that part in the preamp out. That 12ax7 and 12au7 (I think I'm right on the second one.... it's been a long time since I owned mine) are used to drive the power section (MOSFET maybe?). There are 2 or 3 more 12ax7 tubes in the preamp section.

So, to me, it won't really be the sound of the SVT III through the cabs running it into a power amp straight off the preamp. It'll sound fine. But it just won't have the grit you could get through cabs otherwise.

Keep in mind, I last owned one in the late 90s. So I could be remembering incorrectly.
Click to expand...

You'll still get the preamp tube sound (and grit) through the gain. The power amp tubes are a non factor in my question and not to sound short and sound like a d×$k... but that wasn't my question. Sorry but Happy Holidays.

Does someone out there know PLEASE?!
 
#6
BassYerFaceoff said:
You'll still get the preamp tube sound (and grit) through the gain. The power amp tubes are a non factor in my question and not to sound short and sound like a d×$k... but that wasn't my question. Sorry but Happy Holidays.

Does someone out there know PLEASE?!
Click to expand...

Ha! Not offended. Good luck with this. Wish I could help.
 
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#7
The manual looks pretty clear to me. It doesn't give dBu levels but since you have a knob to control it you should be fine.

The schematics show that the preamp out is unbalanced.
upload_2018-12-20_3-14-55.png
 

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#9
Preamp out is unbalanced, just a phone jack. I'm not sure what the signal level is like, I've never used that on mine. You could try an adapter cable (TS phone plug to XLR), it might be hot enough to drive the power amp.

Line out is balanced (XLR or TRS phone jack) but I don't think you'll get anything near 1.4V out of it. I've run mine into a board and as I recall it's closer to a mic level than a hot line level.

Get yourself a small mixer to put between the line out and power amp in. It should solve the problem and you'll find lots of other uses for it ;)
 
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#10
rickdog said:
Preamp out is unbalanced, just a phone jack. I'm not sure what the signal level is like, I've never used that on mine. You could try an adapter cable (TS phone plug to XLR), it might be hot enough to drive the power amp.

Line out is balanced (XLR or TRS phone jack) but I don't think you'll get anything near 1.4V out of it. I've run mine into a board and as I recall it's closer to a mic level than a hot line level.

Get yourself a small mixer to put between the line out and power amp in. It should solve the problem and you'll find lots of other uses for it ;)
Click to expand...

Do you know if using the adapter from 1/4" to XLR from the "PREAMP OUT" would in effect, make it a balanced line into the power amp. If it does I'm sure it'll be hot enough.
 
#12
A balanced input just uses the difference between the two signal lines. If you're sending a balanced signal into it, the two signal lines have the same signal, just opposite polarity (positive on one, negative on the other).

You can connect a single-ended signal to the balanced input, one signal line is the signal and the other is ground (no voltage). You lose the noise canceling benefits of a balanced line (usually not a big issue for a short cable run), but it works just fine.
 
#15
BassYerFaceoff said:
You'll still get the preamp tube sound (and grit) through the gain. The power amp tubes are a non factor in my question and not to sound short and sound like a d×$k... but that wasn't my question. Sorry but Happy Holidays.

Does someone out there know PLEASE?!
Click to expand...

There's no power amp tubes in that amp. Power amp is solid state.
 
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#17
#18
Jazz Ad said:
Yes and no.
Power comes from MOSFET, so solid state but the power section is driven by a preamp tube that plays a role in the tone of the amp as a whole.
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Yes, but as you said the power section is MOSFET. I usually hear the tubes you're talking about referred to as "driver" tubes. I use the 6-PRO which is the same amp with a bigger power section and there sure aren't any power tubes in it.
 
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#20
InhumanResource said:
Yes, but as you said the power section is MOSFET. I usually hear the tubes you're talking about referred to as "driver" tubes. I use the 6-PRO which is the same amp with a bigger power section and there sure aren't any power tubes in it.
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I want to use THE AMPEG SVT3PRO "PREAMP OUT" (Preamp tubes, the POWERAMP on the SVT IS NOT USED) ... I'm not going to use THE POWERAMP ON the SVT... That's why I bought the CROWN POWERAMP...
 
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