New AMP day help

[Raw N Low]

I played through it today and at first thought my bass was playing up as the amp was really quiet. To get a decent volume I had to crank the gain near max and the volume (this is on power amp A not mono bridge) and the limiter kept flashing. Before blaming the bass I swapped the svt 4 pro to a svt classic which is at our rehearsal space and the bass was blaring at noon with gain and master, 3x the volume of the svt 4 pro. These were played through a ampeg 6x10 cab. Before I went I set up the svt 4 pro in mono bridge mode and while there was a noticable volume boost I still had to crank the gain and master way past noon. So what could it be? A blown tube? Dodgy head? Thanks for all the replys tho guys, I wanna get this head blaring! I set up the mono bridge with a standered speaker cable so could that be the cause of the low volume? I'm not sure what year the head is but it looks brand new

I'm going to hook up my 4 pro now and see if I can diagnose for you. The 4 pro has 3 tube in the preamp section.

Here is a hybrid tube tip -- Tubes doesn't always equate to tube distortion. Most hybrid designs are set up to give you warmth and clean headroom. I'm concerned that your limiter is flashing at full and quiet output. I'll report back in a minute...gotta dig out my amp.

 

[Ecko]

Thank you!

 

[Raw N Low]

Here's my old doom rig. Not pretty as everything was in storage. I got the 4 pro in channel A going through a neo 12. I'll let you know in a minute.

 

[Ecko]

I opened it up to have a look inside, I think one of the tubes has been replaced as it's a different colour to the other two

 

[Raw N Low]

Ballsyness confirmed. Crazy loud playing my G&L L5500 > 4 pro > Baer 112. I initially had the master at 1 o'clock and moved it to noon. I turn compression off and it got even louder.

Here is a screenshot of my settings.

My suggestion? Take it to a tech. It could have a bad tube, need cap replaced, and cleaning. Hybrid amps need love too. My SVP 1600 has a bad channel that distorts and is basically a 4 pro with no preamp. I used to run this rig:

4pro+SVP1600 > (2) 410's and (2) 115's. It was stupid loud and I could have thrown another stack in the mix.

 

[Ecko]

Ballsyness confirmed. Crazy loud playing my G&L L5500 > 4 pro > Baer 112. I initially had the master at 1 o'clock and moved it to noon. I turn compression off and it got even louder.

Here is a screenshot of my settings.
View attachment 3392400

My suggestion? Take it to a tech. It could have a bad tube, need cap replaced, and cleaning. Hybrid amps need love too. My SVP 1600 has a bad channel that distorts and is basically a 4 pro with no preamp. I used to run this rig:

4pro+SVP1600 > (2) 410's and (2) 115's. It was stupid loud and I could have thrown another stack in the mix.

Thanks for the help dude, I might have to find a tech to look at it

 

[Raw N Low]

I opened it up to have a look inside, I think one of the tubes has been replaced as it's a different colour to the other two

I'd take it to get cleaned. I forgot to mention that the fan on my 4 pro squeaked for 30 seconds upon power up. These amps are fairly reliable and no way to know how the previous owner cared for the amp.

Sitting at 26 amps in the stable, I'd happily take it off your hands! You got a US model to boot.

 

[Ecko]

I'd take it to get cleaned. I forgot to mention that the fan on my 4 pro squeaked for 30 seconds upon power up. These amps are fairly reliable and no way to know how the previous owner cared for the amp.

Sitting at 26 amps in the stable, I'd happily take it off your hands! You got a US model to boot.

I spoke to my local bass tech (hes been doing my set ups for years) and he said it sounds like one of the tubes has gone and might need replacing, would that sound about right? If the tube has gone will different brand tubes make any diffence to the tone? As I wouldnt mind some mild drive and grit.

 

[Raw N Low]

I spoke to my local bass tech (hes been doing my set ups for years) and he said it sounds like one of the tubes has gone and might need replacing, would that sound about right? If the tube has gone will different brand tubes make any diffence to the tone? As I wouldnt mind some mild drive and grit.

Very possible to have weak output due to a bad tube in the input stage. Some people swear that different brand of tubes make a difference to sound. I'd say go for a good set of quality 12AX7's for warmth and noise reduction.

 

[Ecko]

Very possible to have weak output due to a bad tube in the input stage. Some people swear that different brand of tubes make a difference to sound. I'd say go for a good set of quality 12AX7's for warmth and noise reduction.

I've never owned a tube amp up until now. I was looking at Mesa boogie 12xa7 but what would you reccomend tube wise for a slightly overdriven tone?

 

[Raw N Low]

I've never owned a tube amp up until now. I was looking at Mesa boogie 12xa7 but what would you reccomend tube wise for a slightly overdriven tone?

Although a 4 Pro has driver tubes, you aren't going to get tube distortion from the head alone. You will be able to get a bit of growl and bark when pushed to the edge but that's about it. I would recommend getting a drive pedal to get the desired effects your looking for. This is a hybrid amp and most by design don't produce overdrive unless there is simulation built in. I love true hybrids (tubes throughout the pre-section) to provide a bit of warmth and roundness to my sound. Also, I'm not spending $200 - $300 dollars to replace expensive power tubes pending usage, and instead only $30 - $50 on a nice matched set of preamp tubes.

Also, keep in mind that the 4 pro is two amps in one unit. A and B sides can be bridged via a mono bridge cable however, please notice the break down per side:

RMS Power Output: 300-Watts x 2/900 (mono-bridged @ 8 Ohms)
RMS Power Output: 490-Watts x 2/1200 (mono-bridged @ 4 Ohms)
RMS Power Output (2 Ohms): 600-Watts x 2

That means if you're running an SVT 610 HLF, you only get 490 watts per mono side. 1200 watts using a bridge cable. My Baer 112 was barking and shaking the house only receiving 300 watts running at noon but, it's a very efficient cabinet. Once you get your amp looked at and fixed, you might find the cab to be very dark sounding. YMFV.

So you might say, "The AMPEG 4pro won't distort? That sucks!!!". Keep in mind that this head was designed to give players power and flexibility and reliability on the road or studio. An experienced sound guy will love it because they shouldn't hit any snags running this amp in the front house and you get the sound you need on stage (there's a DI level as well). The amp will give you rock tones but, take advantage of your favorite drive pedal to get your tones.

Dang, I almost forgot that this amp is "effects processor" friendly! That's another good way to get the kind of crunch and tone you are looking for. Also, check and make sure the amp is set up to run in "stereo" and not "mono bridge". That could cause output issues as well. It's a little button on the back that is easy to miss and may require a ball point pen to engage and disengage. It's #31 at the bottom of the diagram.

 

[MarkA]

Sounds like the OP doesn't need a special cable to bridge his particular amp but, for those who do and end up making one, I'd recommend labeling it clearly as such to avoid mixups with other cables. I'd label which end went to the amp, too.

I'll also note that not all amps bridge in the same way (my old Lab Gruppen fp2200 is weird that way -- bridge cable was different than I anticipated, but I'd have to look at the manual to refresh my memory as to how) best to see your manual to be safe.

OP, good luck with your amp -- hope that it turns out to be something as simple as cleaning a contact or replacing a bad preamp tube.

 

[Ecko]

Although a 4 Pro has driver tubes, you aren't going to get tube distortion from the head alone. You will be able to get a bit of growl and bark when pushed to the edge but that's about it. I would recommend getting a drive pedal to get the desired effects your looking for. This is a hybrid amp and most by design don't produce overdrive unless there is simulation built in. I love true hybrids (tubes throughout the pre-section) to provide a bit of warmth and roundness to my sound. Also, I'm not spending $200 - $300 dollars to replace expensive power tubes pending usage, and instead only $30 - $50 on a nice matched set of preamp tubes.

Also, keep in mind that the 4 pro is two amps in one unit. A and B sides can be bridged via a mono bridge cable however, please notice the break down per side:

RMS Power Output: 300-Watts x 2/900 (mono-bridged @ 8 Ohms)
RMS Power Output: 490-Watts x 2/1200 (mono-bridged @ 4 Ohms)
RMS Power Output (2 Ohms): 600-Watts x 2

That means if you're running an SVT 610 HLF, you only get 490 watts per mono side. 1200 watts using a bridge cable. My Baer 112 was barking and shaking the house only receiving 300 watts running at noon but, it's a very efficient cabinet. Once you get your amp looked at and fixed, you might find the cab to be very dark sounding. YMFV.

So you might say, "The AMPEG 4pro won't distort? That sucks!!!". Keep in mind that this head was designed to give players power and flexibility and reliability on the road or studio. An experienced sound guy will love it because they shouldn't hit any snags running this amp in the front house and you get the sound you need on stage (there's a DI level as well). The amp will give you rock tones but, take advantage of your favorite drive pedal to get your tones.

Dang, I almost forgot that this amp is "effects processor" friendly! That's another good way to get the kind of crunch and tone you are looking for. Also, check and make sure the amp is set up to run in "stereo" and not "mono bridge". That could cause output issues as well. It's a little button on the back that is easy to miss and may require a ball point pen to engage and disengage. It's #31 at the bottom of the diagram.

View attachment 3394555

I'll just get stock replacement tubes tubes the and hopefully it'll fix the problem!

 

[BasturdBlaster]

I have rolled tubes a few times in my 4 pro, overall makes little to no difference in tone in my opinion.
I wouldnt spend too much on new tubes for that reason.
The stock tubes are typically a GrooveTube with a red label with the other two having no brand or label.

Im not sure exactly what your amp is doing but I would confirm that both sides (amps) are working and maybe clean the FX and Pre/power loops by spraying a 1/4" jack and plugging it in and out a few times in each jack.

Also, IMO, these amps can get loud but not until you reach the last third of the master and gain. Beware that any "scooping" of the eq or use of the ultra low button (more scoop) will sound good solo but you'll be lost in the mix with a band.

Beware of putting these in a rack case, without a hole on the side it will get very hot in no time.

I have had mine cranked beyond reasonable amounts and I have never seen the "limit" light come on at all but the "peak" light is on a lot due to my high gain setting.

Best of luck!

 

[Ecko]

Although a 4 Pro has driver tubes, you aren't going to get tube distortion from the head alone. You will be able to get a bit of growl and bark when pushed to the edge but that's about it. I would recommend getting a drive pedal to get the desired effects your looking for. This is a hybrid amp and most by design don't produce overdrive unless there is simulation built in. I love true hybrids (tubes throughout the pre-section) to provide a bit of warmth and roundness to my sound. Also, I'm not spending $200 - $300 dollars to replace expensive power tubes pending usage, and instead only $30 - $50 on a nice matched set of preamp tubes.

Also, keep in mind that the 4 pro is two amps in one unit. A and B sides can be bridged via a mono bridge cable however, please notice the break down per side:

RMS Power Output: 300-Watts x 2/900 (mono-bridged @ 8 Ohms)
RMS Power Output: 490-Watts x 2/1200 (mono-bridged @ 4 Ohms)
RMS Power Output (2 Ohms): 600-Watts x 2

That means if you're running an SVT 610 HLF, you only get 490 watts per mono side. 1200 watts using a bridge cable. My Baer 112 was barking and shaking the house only receiving 300 watts running at noon but, it's a very efficient cabinet. Once you get your amp looked at and fixed, you might find the cab to be very dark sounding. YMFV.

So you might say, "The AMPEG 4pro won't distort? That sucks!!!". Keep in mind that this head was designed to give players power and flexibility and reliability on the road or studio. An experienced sound guy will love it because they shouldn't hit any snags running this amp in the front house and you get the sound you need on stage (there's a DI level as well). The amp will give you rock tones but, take advantage of your favorite drive pedal to get your tones.

Dang, I almost forgot that this amp is "effects processor" friendly! That's another good way to get the kind of crunch and tone you are looking for. Also, check and make sure the amp is set up to run in "stereo" and not "mono bridge". That could cause output issues as well. It's a little button on the back that is easy to miss and may require a ball point pen to engage and disengage. It's #31 at the bottom of the diagram.

View attachment 3394555

Right so I used the new mono cable today and the had the gain set at 3 and the master barely turned up and it was thunderous! I was grinning ear to ear. This was through a 4ohm 4x10 ampeg classic. The limiter kept flashing on E string now and then. Is that something to be worried about? Also with the 1+2 mono bridge cable do I use it for power amp a or b if I dont want to use the whole 1200w? My main rig is a hartke 4x10 hydrive 1000w 8ohm so would the wattage from mono bridge be 900w instead of 1200?

 

[Raw N Low]

Right so I used the new mono cable today and the had the gain set at 3 and the master barely turned up and it was thunderous! I was grinning ear to ear. This was through a 4ohm 4x10 ampeg classic. The limiter kept flashing on E string now and then. Is that something to be worried about? Also with the 1+2 mono bridge cable do I use it for power amp a or b if I dont want to use the whole 1200w? My main rig is a hartke 4x10 hydrive 1000w 8ohm so would the wattage from mono bridge be 900w instead of 1200?

Glad to know your getting some output. Do not use the mono bridge cable on amp A or B! That cable should only be used on the mono bridge speakon output. Make sure to label it so you dont get it mixed up.

If you run the amp mono bridge into the Harke, you will get 900 watts into the cab.

 

[Ecko]

Glad to know your getting some output. Do not use the mono bridge cable on amp A or B! That cable should only be used on the mono bridge speakon output. Make sure to label it so you dont get it mixed up.

If you run the amp mono bridge into the Harke, you will get 900 watts into the cab.

Lovely. Thanks for help dude. Do I use a bog standard speakon cable for power amp a and b? Or is there another special one I need to get.

 

[Raw N Low]

Correct, you will need a standard speakon cable for amp connections A and B.

 

[Ecko]

Correct, you will need a standard speakon cable for amp connections A and B.

Only problem I have now is the limiter light is flashing but the tone and volume are fine and the amps dont sound like they're gonna blow. Should I be worried?? I mostly have my setting all noon except mids which are frequency 2 at 3 o'clock and treble which is 2 o'clock. (Gain is on 2/3 oclock and master is barely up) My EQ is flat except 2k boost to cut through more.

 

[Raw N Low]

Only problem I have now is the limiter light is flashing but the tone and volume are fine and the amps dont sound like they're gonna blow. Should I be worried?? I mostly have my setting all noon except mids which are frequency 2 at 3 o'clock and treble which is 2 o'clock. (Gain is on 2/3 oclock and master is barely up) My EQ is flat except 2k boost to cut through more.

Nothing to worry about if your getting some intermittent flashing on the amp. If you don't see that light flicker a little here and there, then you aren't trying hard enough.

Trust your ears and embrace the tone.