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1970s ampeg svt questions

jtylerrelyt

jtylerrelyt

Aug 6, 2023
11
24
#1
I recently purchased a early 1970s svt head (black line) from guitar center and I had questions about the rear inputs/outputs. This will be my first tube head so I want know what to do correctly when I actually receive the head. Below I’ll attach some images from reverb on what I’m talking about, also I messaged the sellers to ask them to no response. My questions are about the 4 inputs/outputs on the back, there are 2 ext amp inputs/outputs, 1 300w power output, and 1 ext speaker output. Also how would one di out of this head since there is no xlr? I have an idea on what 2 of these are but I want to be sure given the age and that it’s my first tube head.
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#2
Sweet amp, I have one just like it.

so you plug a 4ohm cab (or 2, 8ohm cabs daisy chained) into the 4 ohm speaker tap on the left.

the right is only connected if you’re running enough cabs down to 2ohms. So another 4 ohm or 2, 8 ohms. There’s actually a switch In that ext speaker jack that lets the amp run at 2ohms.

As far as xlr out, there is none, they were mic’ing cabs back then, get a separate DI box.

Those amp in/out are to slave other amps, I don’t think you can use them as a line out or effects loop.
 
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#3
thisSNsucks said:
Sweet amp, I have one just like it.

so you plug a 4ohm cab (or 2, 8ohm cabs daisy chained) into the 4 ohm speaker tap on the left.

the right is only connected if you’re running enough cabs down to 2ohms. So another 4 ohm or 2, 8 ohms. There’s actually a switch In that ext speaker jack that lets the amp run at 2ohms.

As far as xlr out, there is none, they were mic’ing cabs back then, get a separate DI box.

Those amp in/out are to slave other amps, I don’t think you can use them as a line out or effects loop.
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Thanks for the reply. What exactly is a slave when it comes to amps?
 
#11
Dust2Dust said:
I just learned something :thumbsup: Thanks
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This applies to 99.987% of all tube amps. Not just SVTs. If it has a tube power amp section with transformers, be sure to connect a speaker. This doesn't apply to 99% of hybrid (tube pre/Solid State power), class D, or all SS (pre and power) amps. When in doubt RTFM before you fire up the amp!!! Also note that there are some (generally lower powered) all tube amps that do allow use without a speaker load. The Ampeg PF20T and PF50T and possibly an Ashdown Little Bastard (the new one) are a couple I can think of. Again, be sure to Read The Friendly Manual.
 
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#12
thisSNsucks said:
Those amp in/out are to slave other amps, I don’t think you can use them as a line out or effects loop.
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I have a vintage B25, which has one such jack. I have succesfully used it both as either preamp out or power amp in. So with two you 'might' be able to use them even as effects loop, although I imagine that'd be a parallel type, not series like in modern amps.
 
#14
jtylerrelyt said:
I recently purchased a early 1970s svt head (black line) from guitar center and I had questions about the rear inputs/outputs. This will be my first tube head so I want know what to do correctly when I actually receive the head. Below I’ll attach some images from reverb on what I’m talking about, also I messaged the sellers to ask them to no response. My questions are about the 4 inputs/outputs on the back, there are 2 ext amp inputs/outputs, 1 300w power output, and 1 ext speaker output. Also how would one di out of this head since there is no xlr? I have an idea on what 2 of these are but I want to be sure given the age and that it’s my first tube head.
View attachment 5166048 View attachment 5166049
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congrats, as an AMPEG fan, an avid watcher of GC, REVERB,EBAY etc...I watched this amp, I felt for the older guy selling it, you could tell it just got to heavy, seemed well loved. I recommend the heritage 810, or svt 212av for that amp, both of them 4ohms, both of them sing,
 
#15
I love the warning disclaimer on the back - "continuous exposure to high sound pressure levels may result in irreversable loss of hearing acuity." Didn't the Acoustic 301 bottom have a similar statement? Played through a 371 set-up on loan WAY back in the day....trying to remember.
 
#16
ahc said:
possibly an Ashdown Little Bastard (the new one)
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Yes the current LB30-2N and the current version of the CTM-15 have built in loads, so they can run without a speaker.

Definitely RTFM if you don't know for sure. None of the older LB30, CTM30s, CTM30 Little Stubby, or CTM15 have a built in load...so connecting a speaker is essential.
 
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