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Ampeg SVT4 por questions

V

vij

Nov 21, 2007
30
0
#1
Hi. This is my first mail here as I am new here.

I have been changing from a Ampeg SVP PRO preamp with a SVT 300 all tube power amp (Same pre amp and power amp as SVT2 Pro but in separate modules) to a SVT4 Pro. The main reason to change is that my SVT2 is about 110 lbs in the rack and the SVT4 pro is 50 lbs.

I have some questions about my new (used) amp.

I run it into a SVT410 HLF speaker and i am using a USA Fender Jazz 62 reissue.

*The first question is the Gain. I have to turn it up to one or two o clock position to get the LED to blink.

On my previous amp I had the gain at 10-11 o clock position.

Is this normal for a SVT4 Pro. I swapped the preamp tubes between my old amp and the new one just to test and it is no difference.

*Second question is about the speaker connection. For the moment I only have a Speakon-tele cable but I will get a proper speakon-speakon cable.

I tried mono/bridged and also to use stereo and only using one channel. I did not notice any difference at all. Is it possible to run the amp with full power (mono bridged) with the speakon-tele cable?

I have been reading somewere that it needs a special cable to be able to run it in mono bridge. The rumer sais that it is not the same cable as you use if you run the amp in stereo mode. Is this truth? What cable should I use?

*Third question is if I manages to run the amp in mono brigde will the speaker (SVT410 HLF) be able to handle the power or will it all end up in smoke and tears.

I love the sound of this combination and was thinking that I might need two SVT410 HLF speakers to get the full effect of this amp but I would be happy if I dont need two as I dont like to carry to much stuff around as the main reason to replace my old amp was the weight.

Jocke
 
#2
Like many issues on TB, this can be searched for and found on TB. You need a 4-conductor Speakon plug on the amp-end of the speaker cable. Instead of the traditional 1+=+, 1-=- for the conections, I believe it's 1+=+, 2+=- for bridged mono mode. Check out your manual. If you don't have a manual, then Ampeg has downloadable ones for free on their website (www.ampeg.com).

My SVT 4 Pro's gain LED goes on at about the same place. It's nothing to worry about. Turn it to where you like the tone, then control the output volume with the master. Also, many believe that the active graphic EQ must be in use and boosted to get the full volume out of the amp.

You can put a 1,000,000 watt capable amp on a 10 watt capable speaker, if you want. Just watch how loud you get the amp; listen for distortion. This subject has been HEAVILY covered on TB. I would suggest a search in the forums for more details on this one. The short answer is, though, that your setup is just fine. BTW, if you want to get rid of that old SVT 300, let me know :)
 
#3
Thanks for the answer.

My old amp is unfourtnuantle not a good old SVT 300. Ampeg introduced a rack mounted power amp called SVT 300 at the same time as they introduced the "original" SVT2 so the power amp is a normal SVT2 power amp. Very nice but just to heavy for my back.

Jocke...........
 
#4
I don't think you need a four conector speakon. I called and talked to someone at Ampeg a few weeks ago about this same thing for an SVT5, and they said all you need to do it rewire a standard speakon to the 1+, 2+ on the amp side of the cable. I also waisted $10 getting a shop to do this for me. It is simple to rewire speakon, just open the end you want to rewire, then unscrew the leads and reattach to the correct connections. You'll see what I mean when you open the cable. Just be sure to mark the end of the cable you rewired if it's a speakon to speakon cable.

As far as the speakon to 1/4", I'm not sure.

When I did this, I wasn't too blown away by the supposed 1300 watts I was supposed to get. There wasn't much increase in the volume the amp was putting out. I'm kind of sick of my Ampeg setup as of latley, so when it didn't have a big change it tone/volume it just made me want to get rid of this stuff even faster. But that's just me. Sorry for the tangent.
 
#5
There are two, four, and eight conductor speakon plugs. A two conductor plug only has 1+ and 1-. A four conductor plug has 1+, 1-, 2+, and 2-. You need the four conductor plug to achieve a 1+/2+ connection for bridged mono. The 1/4" end will stay normal: Tip=+, sleeve=ground.
 
#6
vij said:
Thanks for the answer.

My old amp is unfourtnuantle not a good old SVT 300. Ampeg introduced a rack mounted power amp called SVT 300 at the same time as they introduced the "original" SVT2 so the power amp is a normal SVT2 power amp. Very nice but just to heavy for my back.

Jocke...........
Click to expand...

That's kinda' what I've been hoping to find...just a rackmount, all-tube, power amp.
 
#7
Warpeg said:
That's kinda' what I've been hoping to find...just a rackmount, all-tube, power amp.
Click to expand...

It might just be a small problem. I live in Europe and we run 220 volts here. From memory I dont think that the power amp has a 110/220volt selector switch so i think it might be useless in a 110 volt country:( . I will check out if it has a 110/220 volt selector switch if you are interested.

Jocke.........
 
#10
petersenbass said:
is there a diagram,video, or detailed instructions on how to rewire a 4 conductor speakon to work as a mono cable for the SVT4-Pro?

If I unscrew the connecter will it make sense? I'm waiting on the cable to get here. I;ve seen the +1 = + stuff, will that make sense when I get it?
Click to expand...

+1 :help:

i love the tone of this amp, but i did find it mildly frustrating that i have to buy a special cable and then mod it to run it at full power; seems like it should only be a matter of pushing the "stereo/mono" on the back. :hmm:
 
#11
yeah, when you see the cable undone it makes sense. you can see the little +1/-1 right inside there. this confused the hell outta me as well. but thanks to the trusty geniusis here i was able to figure it out. but just as stated before it wasnt that grand of a volume increase at all, i was pretty bummed myself. i thought this would be the loudest amp ever, now im thinking about going for a meager 300 tube watts in the svt cl or vr. but i still cant fathom how thatd be louder or as loud then the "alleged" 1200 watt 4pro. oh well....
 
#13
It's LOUDER in mono than in dual-channel.

edit to remove stupid typo....


IXNAY <<<<And it runs mono at 2.........>>>>> IXNAY

Good job of fat-fingered typing......... but bad information if you believe it.

Nope it runs MONO at 4

It runs DUAL CHANNEL at 2

But it is indeed louder in mono........
 
#18
question about preamp tubes on the 4 pro (dont mean to jack the thread). would swapping out the tubes in the pre for better or different ones make a difference? or is it a waste of time and money? anybody else do this or know any info on the 4 rpo and whether a tube change would help with tone?
 
#19
Hi, I had an svt4 for 3 or 4 years and I know this head inside and out.

About the gain led, that's really no big deal, and it's normal that the gain position varies from amp to amp and from player to player, I used to run it pretty high, like 3 o'clock, that's where it sounded its best.

For the mono bridge cable, if you bought the head new, the cable is supplied with the head, it's in the box and is labeled mono-bridge. you shouldn't have to buy it separatly, if your svt4 is new and you don't have the cable, go back to the place where you bought it and ask them for it.
 
#20
vij said:
It might just be a small problem. I live in Europe and we run 220 volts here. From memory I dont think that the power amp has a 110/220volt selector switch so i think it might be useless in a 110 volt country:( . I will check out if it has a 110/220 volt selector switch if you are interested.

Jocke.........
Click to expand...

Some of the SVT300 may have a universal transformer. No switch, but probably re-wirable inside. There were, however, domestic-only and export-only versions, mostly quite early in the SLM Ampeg time, and that is when the SVT-300 was made.

It is "easy" to find out..... if the power transformers have 4 wires on the mains side, it is re-wirable. if it has two wires only, it is not.
 

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