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Vintage Ampeg SVT Question

#21
According to the JDI manual the DI is virtually invisible to the amp.


from the manual -
"Connect your amp as usual, then connect a ¼” to ¼” cable from the second (parallel) speaker cabinet jack to the JDI. Because of the high impedance and low draw from the JDI, the amp will only see the speaker cabinet so you do not have to change the amplifier’s impedance setting. Depressing BOTH the -15dB PAD switch and the SPEAKER switch inserts a special circuit that will protect the JDI from overload and allow the parallel speaker connection to be made safely. Depressing the SPEAKER switch also introduces a band-pass filter circuit that rolls off the highs and lows in order to better emulate the performance of a typical 12" speaker."


So adding a parallel jack to the cab should be safe as long as I don't daisy chain the cab with another cab which will change the load impedance that the SVT "sees". I spoke to my tech and he said adding a parallel Jack would be $20 job.
 
#23
coreyfyfe said:
I've used the country man, that's the way to go if you want to DI off of the speaker out. It's rated to handle the equivalent of 2800 watts into 4 ohms according to the manual. It works by presenting a high impedance to the signal so it doesn't really appear in line with signal and the amp only "sees" the cab but it's able to pinch of a little signal to be sent out through the DI.
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This is what I'm talking about. The above sounds correct. I'm curious if the JDI functions the same way.

bassboysam said:
According to the JDI manual the DI is virtually invisible to the amp.
Click to expand...

As long as we're talking about the OUTPUT stage of the amp. If the JDI is set up the same way as the Countryman, you should be good. I'd email Radial and ask them if you can use the JDI as a speaker DI. Point them to this thread if need be.


bassboysam said:
So adding a parallel jack to the cab should be safe as long as I dint daisy chain the cab with another cab which will change the load impedance that the amp "sees".
Click to expand...

That's technically correct, but I really recommend against it. I'd just use the "Thru" jack on the JDI once you get an OK from Radial.

Only YOU will know the additional jack is for the DI (unless you marked it "DI Only" or something like that.)

Someone might borrow your rig down the road, or someone else may set it up, etc... the chances are too great of some knucklehead not understanding the impedance issues and "giving it a try" and you could do serious damage to your head, or their head.

There are few (if any) amps with a singe 2-ohm output. Most use two 4-ohm outs in parallel. I can't see any advantage to adding the additional jack (vs. the potential misunderstanding it could cause). A Hosa or Radio Shack Y-cable would do the same thing, for 6.99, and would not be a permanent mod.

I'd still rather use the "Thru" jack on the JDI if Radial says it will work.
 
#24
bassboysam said:
from the manual -
"Connect your amp as usual, then connect a ¼” to ¼” cable from the second (parallel) speaker cabinet jack to the JDI. Because of the high impedance and low draw from the JDI, the amp will only see the speaker cabinet so you do not have to change the amplifier’s impedance setting. Depressing BOTH the -15dB PAD switch and the SPEAKER switch inserts a special circuit that will protect the JDI from overload and allow the parallel speaker connection to be made safely.
Click to expand...

That's the stuff. That sounds good.

I'd just hate to add the jack to the SVT cab.

I'd just use a Y-cable, but a parallel jack would work too.

I'm curious if you need to use an instrument cable, or a speaker cable.
 
#25
coreyfyfe said:
You should put that in line with the cab you are using. No modification or second cab necessary. Same set up as the countryman type 85 in that case. The difference is that the JDI rolls off highs and lows to emulate a speaker sound so you get a more "mic'd cab" vibe directly while the Type 85 sends the entire signal directly for EQing at the board.
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My cab only has one input jack. if the amp is plugged in then there is no way form me to connect the JDI to it. That is why I would need another jack installed on the cab.
 
#28
bassboysam said:
My cab only has one input jack. if the amp is plugged in then there is no way form me to connect the JDI to it. That is why I would need another jack installed on the cab.
Click to expand...

Y-cable. Exact same thing as a parallel jack. You can make your own with speaker cable if you're concerned about quality. (Or have your amp tech make you a rugged one.)
 
#31
WINGS012345 said:
Nice. I'm going to get me a Y-cable and test. Radio Shack should carry them. What complaints will I hear from my Sound guy in this if any?
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If it works, he'll kiss your feet.

Most sound guys I meet roll their eyes when I ask them to mic my SVT. That's why I bring my own mic & stand.

Sound guys like anything they can plug an XLR cable into.
 
#32
the jdi absolutely does work as a speaker di. i've used it before. and bob bonner is right...with the speaker di, you'll get a sound like an a-designs reddi di, which is great, but it opens up a whole new ballgame with the mic'ed 810.

also, don't modify a vintage svt or do "tricks" so you don't have to bring a separate box. just suck it up and bring the separate box and do it right. it's so not worth damaging a vintage svt.
 
#34
Well, even if you mic it.... the sound guy still has the ultimate say on how you are going to sound. He can still and probably will eq whats coming from the mic. My expierence, You need to be wireless, and walk out in front during a sound check and tell him the sound your looking for.
 
#35
WINGS012345 said:
Well, even if you mic it.... the sound guy still has the ultimate say on how you are going to sound. He can still and probably will eq whats coming from the mic. My expierence, You need to be wireless, and walk out in front during a sound check and tell him the sound your looking for.
Click to expand...
yep. it really does help. or at least tell the guy before the gig what you're looking for in your tone. you have to be a little proactive about warning soundmen if you have special needs. or if you don't have a lot of experience and not sure about your tone, they can sometimes give you good advice if they don't have their heads up their butts.
 

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