Ampeg SVT 5 Pro gain structure

mybook1234 · #1 07-31-2011, 01:54 PM

Hi, first post on Talkbass but have been reading these forums for awhile now and appreciate the wealth of knowledge here!

I am playing an Ampeg SVT 5 Pro through a 610HLF in mono-bridged and was wondering about the gain structure that needs to be set, more importantly how the Volume knob plays on the total output of the amp. Being that the 5pro is capable of putting out 1350 watts at 4ohms in mono bridge, I dont want to blow a speaker in my 610hlf (600watt capability).

Currently I have the Gain knob set to where the peak LED is illuminated 80% of the time and the Volume at 3 Oclock, and the Master is barely turned up at about 8 Oclock and the limit LED is blinking sometimes (5 pro is reaching full output 1350 watts!)

Should I be turning the Volume knob down and boosting the Master instead? Anyone have a setup like this? If so, how do you guys have the gain structure set? Sorry if this is a dumb question. Thanks!

BassmanPaul · #2 07-31-2011, 02:57 PM

The volume control has no effect on the maximum power put out by the amp. It merely changes how much signal you have to give the amp for it to get to that maximum.

Another point to remember is that, in general, cabinet power ratings are thermal, the point at which the drivers start to melt. In real world terms a cabinet can make use of about half of its thermal rating, in your case about 300W. In bridge you have for too much power for your cabinet.

mybook1234 · #3 07-31-2011, 03:09 PM

Thanks Paul for the reply. So how should I be running this amp with my cabinet? I see a lot of people of the forum running say a SVT 4 Pro (1200w @ 4 ohms) into say a 410hlf (500w @ 4ohms) or 810E (800w @ 4ohms).

Should I be using just the Power Amp A or B speaker outputs instead of the mono bridged? I only have 1 cabinet, and do not wish to get another to split out the 1350 watts of the 5 pro.

Thanks again!

lokikallas · #4 07-31-2011, 03:49 PM

I think you have it set up right, as far as gain structure. You might play with master volume vs. channel volume a little, but really the channel volume could be wide open if I'm not mistaken. As long as the master is kept in check the channel volume's are just percentages of the whole. Basically to balance out the OD and clean channel. I personally would run it bridged mono. I don't see any reason not to, unless you accidentally turn up your master all the way. I don't own one, but I was reading the manual checking them out not too long ago.

BassmanPaul · #5 07-31-2011, 03:55 PM

Personally I've never seen the need to run any of my amplifiers in bridge. I do like to have a bit of extra power available but certainly not double. I would try running off one side of the amp and see if it's enough for what your need. Your cabinet will be safer that way.

mybook1234 · #6 07-31-2011, 04:00 PM

Thanks Lokikallas for the reply! I assumed the same thing regarding the Volume knob, but it looks like it does affect the overall output because why would the limit LED be blinking when my master is barely turned up. For a point of reference, I am not combining the OD channel. Just running the clean channel.

From the Ampeg SVT 5 Pro Manual:

VOLUME: This control adjusts the output level for the clean channel.
MASTER: This control adjusts the overall output level of the amplifier.

BassmanPaul · #7 08-01-2011, 10:36 AM

I think you are missing my point. Even with the gain on 1 and the master on 1 a large enough input signal will drive the amplifier to its full output power. Whatever the position of the controls your amp is still capable of putting out 1300 odd watts.

JimmyM · #8 08-01-2011, 10:44 AM

Paul, in general, of course you are right about thermal power ratings vs real world displacement. But Ampeg rates that cab at 600w real world power handling, and they're one of the very few companies to use real world power handling ratings, so it will, indeed, take right around 600w.

lokikallas · #9 08-01-2011, 11:05 AM

Quote:

Originally Posted by mybook1234

Thanks Lokikallas for the reply! I assumed the same thing regarding the Volume knob, but it looks like it does affect the overall output because why would the limit LED be blinking when my master is barely turned up. For a point of reference, I am not combining the OD channel. Just running the clean channel.

From the Ampeg SVT 5 Pro Manual:

VOLUME: This control adjusts the output level for the clean channel.
MASTER: This control adjusts the overall output level of the amplifier.

I hate it when amps have too many "volume" knobs. It sounds to me like you should set the master as the max volume limit, and use the channel vol for day to day adjustments.

JimmyM · #10 08-01-2011, 11:14 AM

Quote:

Originally Posted by lokikallas

I hate it when amps have too many "volume" knobs. It sounds to me like you should set the master as the max volume limit, and use the channel vol for day to day adjustments.

That strategy might work for some amps, but it works pretty badly on Ampeg amps. They just don't sound right until you get the gain up, even if you like clean sounds.

mybook1234 · #11 08-01-2011, 12:15 PM

Thanks for the feedback everybody! I will try Paul's suggestion of just using the output of the power amp instead of mono bridged and see how that sounds. In theory that will just give me 675 watts of power right? (1350/2 = 675)

I am just a little confused because I keep reading that having so much extra wattages in the amp gives you head room, but whats the point of if you can't turn up the amp?

JimmyM · #12 08-01-2011, 12:23 PM

Quote:

Originally Posted by mybook1234

Thanks for the feedback everybody! I will try Paul's suggestion of just using the output of the power amp instead of mono bridged and see how that sounds. In theory that will just give me 675 watts of power right? (1350/2 = 675)

I am just a little confused because I keep reading that having so much extra wattages in the amp gives you head room, but whats the point of if you can't turn up the amp?

Exactly my thought, too. But headroom is a good thing, and that's why I never do a gig with an amp that has less than 25 watts

BassmanPaul · #13 08-01-2011, 01:18 PM

Quote:

Originally Posted by JimmyM

Paul, in general, of course you are right about thermal power ratings vs real world displacement. But Ampeg rates that cab at 600w real world power handling, and they're one of the very few companies to use real world power handling ratings, so it will, indeed, take right around 600w.

Fair enough Jimmy but, whether thermal or RMS, 1300W is still too much for a 600W cabinet. OP using a single channel at 4Ω you will have about 420W available.