What is SAG?

Re: What is SAG?

It's a type of natural compression usually obtained in a valve amp by the valve rectifier. Kinda 'slows' down the sound and makes the bass a little less tight, more spongy.


I think ;)
 
Re: What is SAG?

Sag is a decrease in power-supply voltage due to a sudden increase in playing volume. It's a type of compression. "Engineer" types (the kind that ruined Fender in the 70's, not ones like me) would say that sag is a bad thing, adn design it out of a power supply. Toneologists like us know that sag can be a desireable component of tone, and select amps based on whether they have it nor not (and to what degree), according to our taste.

Tube power supplies tend to sag more than soild state. Certain tubes sag more than others.

Using decoupling resistors between power supply filter stages causes more sag. Using a choke sags less.

Tube-rectifier-type sag can be simulated with a SS rectifier by adding series resistance.
 
Re: What is SAG?

Sag is caused when I put my foot up a troll's ass so far I lose my shoe. It's so heavy, being a size 14, that the muscles and skin start to elongate causing a visible difference in the appearance of the troll's ass. This is commonly known and referred to as sag.
 
Re: What is SAG?

Sag is caused when I put my foot up a troll's ass so far I lose my shoe. It's so heavy, being a size 14, that the muscles and skin start to elongate causing a visible difference in the appearance of the troll's ass. This is commonly known and referred to as sag.

Gee... and here I was... all set to blame age and gravity.
 
Re: What is SAG?

Sag is a decrease in power-supply voltage due to a sudden increase in playing volume. It's a type of compression. "Engineer" types (the kind that ruined Fender in the 70's, not ones like me) would say that sag is a bad thing, adn design it out of a power supply. Toneologists like us know that sag can be a desireable component of tone, and select amps based on whether they have it nor not (and to what degree), according to our taste.

Tube power supplies tend to sag more than soild state. Certain tubes sag more than others.

Using decoupling resistors between power supply filter stages causes more sag. Using a choke sags less.

Tube-rectifier-type sag can be simulated with a SS rectifier by adding series resistance.

Thanks for taking the time to explain this concept. You made it easy for me to understand. Much appreciated.


Dave
 
Re: What is SAG?

Thanks for taking the time to explain this concept. You made it easy for me to understand. Much appreciated.

Dave

Crap. I'm an engineer. I'm supposed to talk in non-stop techo-mumbo-jumbo so that no normal person ever understands a thing I say, but leaves with the impression that I'm some sort of geek.

I hope they don't revoke my license.
 
Re: What is SAG?

1.) Sag is a decrease in power-supply voltage due to a sudden increase in playing volume.

can u please explain more in detail about this?

Why does it decrease in power supply voltage?


2.) Tube power supplies tend to sag more than soild state. Certain tubes sag more than others.

What causes the SAG in the tubes?

3.)Using decoupling resistors between power supply filter stages causes more sag. Using a choke sags less.

Why does using decoupling resister cause more SAG?

4.) Tube-rectifier-type sag can be simulated with a SS rectifier by adding series resistance.

Series reistance would be a load or what to the power supply?
 
Re: What is SAG?

Software AG - they make a database management system called ADABAS that is a high priced competitor of DB2.
 
Re: What is SAG?

Basically, any electrical circuit (in this case, the power supply of the amp) has some series reistance. It might be an actual resistor, or it might be an "equivalent resistance" - basically a characteristic of the device (like a tube rectifier) that can be modelled as a series resisitance.

So, the output current of the power supply is flowing through this series resistance on it way to the amplifier circuit. Remember ohms law V=IR, where I is the current, R is the resistance, and V is the voltage drop across the resistor. When you play loud, the current increases, so the voltage drop increases, causing the power supply output voltage to DECREASE, or sag.

Tube rectifiers sag more because they are less than ideal, meaning their internal equivalent resistance is high. SS diodes are closer to "ideal", have lower inernal resistance, and sag less.

Chokes sag less because they use their inductance to do a lot of the filtering, so their resitance is lower than a pure resistor that would do the same job. Less resistance, less sag.

Inserting a resistor in series between the PS and the amp will add sag.

I got my mumbo-jumbo workin'.
 
Re: What is SAG?

Thanks for the help

1.) Inserting a resistor in series between the PS and the amp will add sag.

How do u get more SAG alot of SAG?
any other modifacation tricks?

2.) MOst tube amps don't use regulators why is that? does regulators take away the SAG? most solid state amps use regulators why is that VS tube amps they don't use regulators?

3.) How can i play at low volume but have alot of SAG?
 
Re: What is SAG?

so less B+ voltage/output of the power supply is called B+ , so less B+ voltage means more SAG? making the power tubes have less voltage? and less current?
 
Re: What is SAG?

Sag also happens in speakers and makes them sound worse, typically only happens when mounted vertically though (like facing upwards or downwards).
 
Re: What is SAG?

It's an exaggerated droop in your drawers, initially used by prisoners to announce their availability. For some reason, street thugs adopted this as the latest "fashion," leading to copycat styles in the 'burbs.

I have always been amazed that a fashion developed by criminals would inhibit a fast getaway. Seems as though Reeboks and sweatsuits would be more efficient.
 
Re: What is SAG?

What is SAG? and What causes SAG?



Even if you are not a fan of the music, spend $20.00's on the White Stripes DVD, "Under BlackPool Lights", and listen to that beautifull sag from the Twin Reverbs !

Jack White use valve-sag to enhance the sound and feel of the song !

In almost every song you can hear huge amounts of sag !!!

I LOVE IT !!!
;)
 
Re: What is SAG?

Thanks for the help

1.) Inserting a resistor in series between the PS and the amp will add sag.

How do u get more SAG alot of SAG?
any other modifacation tricks?

Something about 100 ohms is a good starting point, but you have to be careful. The voltage drop lowers B+ overall, and that can change the bias of cathode-biased stages.

2.) MOst tube amps don't use regulators why is that? does regulators take away the SAG? most solid state amps use regulators why is that VS tube amps they don't use regulators?

Old tube amps didn't use regulators because high-voltage regulators are expensive. Modern tube amps don't use regulators because old tube amps didn't use them, and we found we like sag in varying degrees.

3.) How can i play at low volume but have alot of SAG?
Use a small amp cranked and/or a power attenuator. A master volume won't do it. There are some amps around with preamp stages that sag, too, but when we say 'sag" we usually mean the output stage.

so less B+ voltage/output of the power supply is called B+ , so less B+ voltage means more SAG? making the power tubes have less voltage? and less current?

No. Sag is not just lower B+. Sag is when B+ dips temporarily in response to loud playing. The short-duration surge in current causes a similarly short-duration sag in B+. This makes the amp more dynamic, giving changes in tone in response to picking dynamics. It also gives a compressed sound, and resulting sustain.

Less saggy amps tend to keep the B+ more stable no matter how loud you play, and are referred to as being "tighter", like Blackface vs. Tweed or Plexi vs. JTM-45.
 
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