Amp - Metal "sag"

[MontyW]

Can anyone explain to me what the term "sag" means when referring to metal tones - I know its to do with EQ but surly it ain't the same as scooping the mids, so is it to do with bass? Anyone? Any linked sound clips to help?

 

[KH Guitar Freak]

Sag is basically a feel thing, which is when you pick on a string, it goes from a fairly tight sound to a looser one, if that makes any sense. IMO, I would generally refer to sag as that, which seems to apply to valve rectification and using the spongy mode...

 

[MontyW]

Thanks - that helps.

 

[MrMarkIII]

"Sag" means the note seems to drop a tiny bit in volume right after it's picked, and then seems to "bloom", or get louder, before it eventually dies out.
This happens with old amps (and modern amps) with tube rectifiers.
Rectifiers change the A/C current coming into the amp into D/C current, because D/C is what electronic devices use. The juice comes from the wall, hits the rectifier, then goes to rest of the amp.
A solid state rectifier is more efficient than the older tube design, so the supply of current remains more constant, no matter if you pick hard or soft.
A tube rectifier reacts more slowly. If you pick hard, the demand for juice goes up, but it takes a bit for the rectifier to catch up.
For a brief moment, there's less juice feeding your amp, so the sound seems to "sag".
Hope this helps

 

[MontyW]

I think I get it LOL

 

[rocksalt7]

EXCELLENT description MrMark...that's just the way I understood it too; very well said.

 

[mrd]

Also, to add:

Since bass frequencies require the most electrical power to amplify, if you're running with tube rectifiers and have your EQ set in a huge V with the volume cranked, every time you go to do a huge, chunky palm muted chord, the bass is going to sap almost all the power right away. So if you're doing a nice chunky rhythm line (like classic Metallica) and you're pickin' away, all those super fast attacks are going to be working the rectifier hard. Not that it's bad or anything. It's just the fact that it's not instantaneous in its rectification can mean that ultra-fast & tight bass response can't really be achieved. This is often why people say the MKIV is so much tighter is because of it's diode rectification. It's also voiced differently which helps too. but I think the classic Recto sound in a lot of people's minds is with the sag of the recto tubes.

Hope it helps.

 

[Large_Filter_Cap]

Also, to add:

Since bass frequencies require the most electrical power to amplify, if you're running with tube rectifiers and have your EQ set in a huge V with the volume cranked, every time you go to do a huge, chunky palm muted chord, the bass is going to sap almost all the power right away. So if you're doing a nice chunky rhythm line (like classic Metallica) and you're pickin' away, all those super fast attacks are going to be working the rectifier hard. Not that it's bad or anything. It's just the fact that it's not instantaneous in its rectification can mean that ultra-fast & tight bass response can't really be achieved. This is often why people say the MKIV is so much tighter is because of it's diode rectification. It's also voiced differently which helps too. but I think the classic Recto sound in a lot of people's minds is with the sag of the recto tubes.

Hope it helps.

It helps. Since the Si-diode rectification creates a tighter and instantaeous response, I would imagine a Dual-Rec, or a Roaster or Road-King to be supreme in this department, interms of fast, responsive heavy chuncky attacks.??

 

[eudaimonia02912]

The Mark series is tighter and more responsive than the Recto series, even when the Recto series is in SS mode, IMO. Apparently this is a common opinion, from what I've read.

 

[Scary]

You guys rock. I knew what sag was, but now I also know what causes it and how it's created!

 

[94Tremoverb]

The Rectifiers have quite a lot of sag even in solid-state diode mode - sag is not just caused by rectifier tubes, it's also a function of the power transformer internal resistance and the amount of filtering. The Rectifiers have a different transformer from the Mark series, although apparently the first 500 used Mark transformers - and are supposed to be much tighter sounding. (I've never played one.)

 

[msi]

The Rectifiers have quite a lot of sag even in solid-state diode mode - sag is not just caused by rectifier tubes, it's also a function of the power transformer internal resistance and the amount of filtering. The Rectifiers have a different transformer from the Mark series, although apparently the first 500 used Mark transformers - and are supposed to be much tighter sounding. (I've never played one.)

Correctly put, the first batch of Rectifiers. The Mark transformers were not limited to just the first 500. My rack rectifier has the MKIII transformers and it's serial number is in the 1000's.

 

[94Tremoverb]

That's interesting - I knew the Racktifiers were suppose to sound different from the regular heads. I thought it might be to do with the physical layout, since I thought the circuit was the same. It might still be, but if the transformers are different too it would make a much bigger difference. I've never played one of these either but it would make sense.

 

[msi]

That's interesting - I knew the Racktifiers were suppose to sound different from the regular heads. I thought it might be to do with the physical layout, since I thought the circuit was the same. It might still be, but if the transformers are different too it would make a much bigger difference. I've never played one of these either but it would make sense.

I can't comment on why it sounds different other than the transformers. It's a revision F board. I don't really care for the pre-1000 crap that gets spouted but the only major difference from my racktifier and later ones are the transformers. Here's what I know, the rev. C board is vastly different from everything that came after. The basic layout is there, but the switching on the orange channel and in the feedback loop was different. The revision E boards introduced the switching scheme that both the F and G revisions used. I haven't seen any pictures of a rev D pcb, so I don't know if it is closer to the C or E revisions. The revision F and G boards are nearly identical. It appears to me the changes were mostly in the switching power supply. Also about the time the boards switched from F to G also came the switch from a serial to parallel fx loop. That change was not on the PCB board though. The racktifiers use the same boards as the heads. The physical layout is more cramped and the choke is externally on the amp rather than internal as in the heads. If they sound different to the heads it's not because of any changes to the PCB boards. There are the stories that George Lynch would look at the transformers of the Dual Rectifiers to see if they had the MKIII transformers as he thought they sounded better. My racktiifer has the MKIII transformer. I haven't heard another revision F rectifier with the replacement transformers though.

As for sag, if you get a chance you'll notice the tone of the amp changes when using the tube rectifiers. Tube rectifiers have a larger voltage drop than the silicon diodes, so the voltages going to the rest of the amp are lower as well. The amp will has less gain. The same thing happens when playing just like mentioned before.

 

[94Tremoverb]

That's very true. The tone changes noticeably even when the amp is at such low volume that sag cannot possibly matter. I'm running a pair of GZ34s in my Tremoverb at the moment - which have a lot less resistance than 5U4s - and there's still a clear difference. The tone in Solid State Diode is harder, very slightly louder and has a tiny bit more bass. I would describe it as hearing a bit more of the iron fist inside the velvet glove than you do with the tube rectifier .

I don't know much about the early revisions or other variants of the Dual Rectifier by the way - just what I've read. I'm pretty sure all the ones I've played have been Rev.G since I don't remember one with a series loop. But even the few Tremoverbs I've played all seemed to sound slightly different, and as far as I know there are no changes at all in those.