In the Spirit of NAMM Anouncements (FAS reactive load box)

Oscarraap said:
Well, if I choose an attenuator, I do need to hook up my cab. So what is the differrence between the two, in technical terms?
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The load box, well, shows your PA a load instead of the speaker and produces a line level signal to send to your axe/interface. This way you can silently record your tube head without blowing it up or needing a cab
 
Thanks everybody for responding, and your patience.

I know what a loadbox is. I know that its not easy to simulate the behaviour of a real speaker that way.
And thats exactly what Im trying to avoid; by keeping my real cab hooked up as a load and using an attenuator instead.

So I would like to know how an attenuator works. Or is it essentially thesame as a loadbox?

Cheers!
 
The "reactive" part of a "reactive loadbox" is simulating a real speaker. How good is the simulation? Here's a quote from Cliff:

FractalAudio said:
Well, for one, the impedance of our load actually resembles a real speaker. The same can't be said about some of the other so-called "reactive loads". Furthermore I've developed proprietary magnetics technology so the impedance changes with applied voltage, like a real speaker does.

Most importantly though, it sounds really good. I've tested just about every reactive load out there (except the Suhr) and ours actually sounds like a real speaker. In fact I'd go so far to say it sounds better than when I use my iso cab as a load.
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Are you able to run large amps at full volume into the LB-2 without damaging the amp? From the front, it looks like there are a larger vents to dissipate heat. I am assuming there is a large heat sink and fan built in as well?
 
guitarcal said:
Are you able to run large amps at full volume into the LB-2 without damaging the amp? From the front, it looks like there are a larger vents to dissipate heat. I am assuming there is a large heat sink and fan built in as well?
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It's never recommended to run a tube amp at full volume understanding that with the master volume at 10 or 11 as the amps will not sounds its best like that with or without a load box.

This is a miss conception, amps have a sweet spot and its not at max volume.
 
Thanks Mikko, I have read this statement, and thats what my question is all about...

To repeat: Im sure the FAS load is good, but A. it's not available yet and B. do i need one? My Mark V amp has a slave out. So maybe an attenuator is enough for me?

Or maybe using an ISO cab as a load is a good idea.

It seems my question doesn't make any sense to you guys, I just want to know more about how an attenuator works technically, so I can decide whether to wait for the Nucleus or go for an attenuator.

Cheers
 
nicolasrivera said:
It's never recommended to run a tube amp at full volume understanding that with the master volume at 10 or 11 as the amps will not sounds its best like that with or without a load box.
This is a miss conception, amps have a sweet spot and its not at max volume.
Click to expand...

This isn't necessarily true, it depends on the amp. It just so happens the "sweet spot" on mine is when the master volume is on 10.
I was more asking from a technical perspective, was curious if the LB-2 heat sinks can handle that much power being thrown at it. Also, for those of us with 100 watt Marshalls, can we run the Master on 10 without damaging the amp?
 
guitarcal said:
This isn't necessarily true, it depends on the amp. It just so happens the "sweet spot" on mine is when the master volume is on 10.
I was more asking from a technical perspective, was curious if the LB-2 heat sinks can handle that much power being thrown at it. Also, for those of us with 100 watt Marshalls, can we run the Master on 10 without damaging the amp?
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What amp do you have?
 
nicolasrivera said:
It's never recommended to run a tube amp at full volume understanding that with the master volume at 10 or 11 as the amps will not sounds its best like that with or without a load box.

This is a miss conception, amps have a sweet spot and its not at max volume.
Click to expand...
Kinda weird to make a statement about "never recommended". I had old JMPs that mushed out above 2 o'clock and others that happily went full tilt. Just the same as single ended amps not liking to be hit hard on the input. Many go ratty but with the right combination they can either sing or literally stop.
 
Oscarraap said:
Thanks everybody for responding, and your patience.

I know what a loadbox is. I know that its not easy to simulate the behaviour of a real speaker that way.
And thats exactly what Im trying to avoid; by keeping my real cab hooked up as a load and using an attenuator instead.

So I would like to know how an attenuator works. Or is it essentially thesame as a loadbox?

Cheers!
Click to expand...
In a past life I was VP at THD Electronics and I guess I know a thing or 12 about attenuators.
Here's the thing, run a line out parallel or before an attenuator with the cab as load, it will work perfectly fine.
I've done IR stuff since Waves released Q clone and been doing this type of set up since 2005.
Also the idea of a reactive load simulating a anything more believable with a bump in the bottom and a shelf on top is ludicrous. Still a static two dimensional curve, and impedance is three dimensional and due to its frequency dependant changes not static.

Love when everybody and their brother believe marketing.

Lastly... The speaker resonance in the Axe with the clean tube pre goes a long way with that.
 
Ed DeGenaro said:
In a past life I was VP at THD Electronics and I guess I know a thing or 12 about attenuators.
Here's the thing, run a line out parallel or before an attenuator with the cab as load, it will work perfectly fine.
I've done IR stuff since Waves released Q clone and been doing this type of set up since 2005.
Also the idea of a reactive load simulating a anything more believable with a bump in the bottom and a shelf on top is ludicrous. Still a static two dimensional curve, and impedance is three dimensional and due to its frequency dependant changes not static.

Love when everybody and their brother believe marketing.

Lastly... The speaker resonance in the Axe with the clean tube pre goes a long way with that.
Click to expand...

Not sure I followed all of that, but Oscarraap seems to want an attenuator that gives same result as a loadbox without any of the tone or feel compromise when he takes his line out signal to a mixer or sound processor. He seems to be asking if he can use an attenuator hooked up that will reduce the sound coming out completely while still putting a load on the amp. Kind of makes sense theoretically, but I have no idea if it would work the same. If that is case- why would people even use loadboxes if they could, in effect, have a variable loadbox effect with an attenuator?

The THD HOTPLATE manual kind of hints at this:

4. Adjust the rotary switch on the Hot Plate to attain the volume you desire. At -0 dB the
loudness is the same as it would be if the amp were running directly to your speakers. The
effective volume will drop in increments of 4 dB as you turn the switch counter-clockwise.
At the -16 dB setting, the potentiometer on the right is activated (at all other settings this
pot has no effect so it does not matter where you set it). When the rotary switch is at -16
dB and the pot is turned fully clockwise, the effective volume will be 16 dB less than your
unattenuated volume. As you turn the pot counter-clock wise, the volume drops smoothly
down to -∞ dB (no sound).
When the rotary switch is at Load, there will be no sound coming through the speakers,
but your amp will still be safely running at full output.



What do you think the best solution is for silent playing/recording for people wanting to use a SLAVE OUT (unfiltered signal tapped from speaker out) from their amp like on a MARK V?

Coincidentally he and I both have Mark V's.
 
Lkdog said:
Not sure I followed all of that, but Oscarraap seems to want an attenuator that gives same result as a loadbox without any of the tone or feel compromise when he takes his line out signal to a mixer or sound processor. He seems to be asking if he can use an attenuator hooked up that will reduce the sound coming out completely while still putting a load on the amp. Kind of makes sense theoretically, but I have no idea if it would work the same. If that is case- why would people even use loadboxes if they could, in effect, have a variable loadbox effect with an attenuator?

The THD HOTPLATE manual kind of hints at this:

4. Adjust the rotary switch on the Hot Plate to attain the volume you desire. At -0 dB the
loudness is the same as it would be if the amp were running directly to your speakers. The
effective volume will drop in increments of 4 dB as you turn the switch counter-clockwise.
At the -16 dB setting, the potentiometer on the right is activated (at all other settings this
pot has no effect so it does not matter where you set it). When the rotary switch is at -16
dB and the pot is turned fully clockwise, the effective volume will be 16 dB less than your
unattenuated volume. As you turn the pot counter-clock wise, the volume drops smoothly
down to -∞ dB (no sound).
When the rotary switch is at Load, there will be no sound coming through the speakers,
but your amp will still be safely running at full output.



What do you think the best solution is for silent playing/recording for people wanting to use a SLAVE OUT (unfiltered signal tapped from speaker out) from their amp like on a MARK V?

Coincidentally he and I both have Mark V's.
Click to expand...
Unless I misunderstood the question was... If I use a cab and an attenuator with the slave out will the speaker be the "reactive" part.
Yes it will as long as it's used.

As I said I've been doing this since long before there was an Axe-Fx or commercial IRs...let alone reactive load boxes.
Actually long before I even went to THD the first time I've been using a Hot Plate for that. Carl Verheyen turned me on to this back in the late 80s or early 90s.

As for the Hot Plates...with the deep switch on they are reactive by way of the inductor being switched in.

Chances are also that with the Mark you can get milage out of turning the amp down via fx return without an attenuator.
 
Also before I forget there's the impedance of your I/o. I still use an ancient red box with the cab sim off since it has a 300 ohm output and when I go into the input of a mic pre, especially something like the UA610 that can be switched down to 500 ohm it mosdef feels different than using 1 meg I/o.
 
An attentuator dissipates part of your signal...it's meant to to knock volume off, a load turns an amp into essentially a pre-amp. Or is used to bench test an amp without a cab.
There are attenuators with loads build it.

When I got my first Scholz attenuator I balked at the price, just as I didn't like spending 200 bucks on my first used Hot Plate. But sure sure would not pay what some builders are asking for their attenuators or loads. The craziness of guys with disposable income when it comes to buying tone...priceless
 
Ed DeGenaro said:
Unless I misunderstood the question was... If I use a cab and an attenuator with the slave out will the speaker be the "reactive" part.
Yes it will as long as it's used.

As I said I've been doing this since long before there was an Axe-Fx or commercial IRs...let alone reactive load boxes.
Actually long before I even went to THD the first time I've been using a Hot Plate for that. Carl Verheyen turned me on to this back in the late 80s or early 90s.

As for the Hot Plates...with the deep switch on they are reactive by way of the inductor being switched in.

Chances are also that with the Mark you can get milage out of turning the amp down via fx return without an attenuator.
Click to expand...


Thanks for your reply.
 
Ed DeGenaro said:
If I use a cab and an attenuator with the slave out will the speaker be the "reactive" part.
Yes it will as long as it's used.
Click to expand...

This is very good news! If I understand correctly, the load of an attenuator only works when volume is reduced to zero. At any other setting of volume reduction, the load of the attenuator is not working. The cab will take the load. Am I right?

This would confirm my hunch. I have no technical understanding. All I know is I dont need a box for a line out, because my amp has line out built in. My conclusion is the accuracy of the simulated load (different brands, reactive versus resistive etc etc.) doesnt matter to me. Because i won't be using the simulated load. All I need to do is get an attenuator, set the volume low, and let my real cab take the load.

Ed DeGenaro said:
Chances are also that with the Mark you can get milage out of turning the amp down via fx return without an attenuator.
Click to expand...

Even more interesting! The fx loop indeed has a level control. How do i approach this, physically connect fx out to fx in with a cable?

Cheers!
 
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