Quality of line out in load boxes (iron man mini 2 & suhr reactive load)

[Wonks]

You've answered your first two questions. Yes, the amp will still see the load, and an active DI box will work if it's one with a -40dB pad on it.

A valve amp interacts with the load it's driving, so you'll get a slightly different output signal from the amp just by changing the speaker used, say from a Celestion Vintage 30 to a G12T-75.

Some speaker attenuator/load boxes are entirely resistive, which will result in quite a different signal coming from the amp than a 'reactive' one that uses inductors and capacitors to try and more accurately represent a speaker's varying impedance characteristics at different frequencies.

This is always going to be a compromise with a speaker attached, and even pure 'reactive' load boxes will give a slightly different sound from the amp.

As all the different load or attenuator boxes have different circuits, it's very likely that a DI box sampling an amp first running into a Suhr Reactive Load and then a Torpedo Cap 8 ohm will sound a bit different.

But what does it sound like passed through the speaker and cab IRs? As these will roll off most of the high frequencies giving the 'bright' sound you get coming direct from the amp, the end results may be very similar, nothing a touch of EQ won't fix. It's not something I've done, so I really don't know.

[hotlegs]

Yes, it really sounds dull. I wrote an Email to support and they told me, this is normal. I play an slo-30, this amp has a line out at the end of the output transformer (speaker side). Taking the ironman as a load and comparing ironman line out vs slo-30 line out, ironman sounds like an old Tapedeck of the sixties. Today I got my fractal x-load, sounds same like slo-30 line out. Now I use the ironman only as power-soak for Appartement level, this works. For recording my Fender amps or my SLO, I use the fractal unit. For SLO I can also use the SLO lineout with x-load or speaker connected. Ironman has obviously an error by design with the line out.

Michael

[Guitarking]

One would start to think there is a cab sim on the Iron Man line out...

[hotlegs]

No, no cab sim. Go to your DAW and listen with no impulse response, it sounds awful. I think it's only bad design, it kills highs and shape the bass a little bit. I think it's not ok, you have to turn to much to compensate in the DAW. For recording, I use another load.

[Wonks]

Yes, it has already been mentioned a couple of times that a lot of these load boxes have a line out with a speaker emulation, which is often not switchable. All these units are slightly different to each other in what they provide.

It is not a design fault, it is a design choice. Some of the manufacturers could be clearer about what the line out is, and whether it has a speaker emulation or not, but a lot do explain it in their manuals.

It does help to read the manuals in advance before purchase, to know as much about the unit as you can.

I don’t claim that these units have great speaker emulations (it’s often just a couple of capacitors and a few resistors), so some will sound better than others. But at sone point the design team will have said that it sounds good enough to them.

Not everyone will want to record a non-speaker emulated signal from the DI out and then pass it through software IRs. A lot will like the emulated signal. So the load box/attenuator needs to have the right features to do what you want.

Personally I’d get a Captor X and use its IRs and record direct from that.

[hotlegs]

Well, I know both Tone King attenuators, the 100 Watt version (this has a selectable DI and line output. The DI output is frequency compensated for direct recording, switchable axis between cone or edge.

This from the manual:

Line Out
The Ironman II's Line-Out jack provides a line-level signal that can be used to drive another amplifier, mixing board, computer sound input, or any other line level input. This is useful if the Line-Out is being used to drive another guitar amplifier, where you need to reduce the level to avoid overdriving the guitar amplifier. The line-out signal is generated from the amplifier input, and does not change as you vary the attenuation knob. The line-out signal will be present even when the attenuator is bypassed. The line-out signal is a non speaker simulated output.

DI Output
In this new design Iron Man II design we included a cab-simulated (OP amp driven) balanced XLR output XLR output. Comparing this analog circuit to some of the most intricate computer-based IRs, we achieved a great sounding output you can send to front of house or use in the studio. The XLR output includes a ground-lift, level, and center/edge of speaker cone simulation switches.

The Tone King mini 30 Watt has only a line out, not marked in the manual as frequency compensated.

Line out: Recording / DI out, impedance 10 k, level -10 dbu

The sound of the mini sounds not frequency compensated for direct recording (I know, how these palmer, redbox etc., all these passive compensated DI boxes sound. Like you said, these are build by resistors and capacitors.

Best how you can describe the line out of the TK mini is, it sounds wit a blanked over the speaker. Anyway, I don't have a problem with the unit, I take it for level reduction and not for recording (Fender Tweed Deluxe) and this sounds very good - better than the captor x with his two choices of attenuation. For a well build loadbox (silent recording) I prefer suhr reactive load or fractal audio x-load. These are reactive loadboxes simulating the behavior of real loudspeakers and they have very clean DI outputs for feeding IR via DAW or feeding another poweramp.

I'm only answering to the first post:

Hi everyone,

Bought a Tone King Iron Man 2 mini. The attenuation is really fantastic! But not sure about the line out. Sounds dull to me. Anyone has the same experience?

and I have the same experience.

Michael

[Guitarking]

Would the Two Notes Cap 8 ohm have a clean line out? As I already have the Iron Man 2 mini, all I need is a good load box with a clean di and the Cap 8 ohm is pretty affordable.
Again the attenuation of the Iron Man 2 mini is very good.

[hotlegs]

Don't know about the quality of the Two Notes. Fractal Audio X-Load is working perfect, they have a sale for 299.- dollar.

[ef37a]

Just a thought?
It is not unknown for the wrong value component to get stuffed into a PCB.

That "dull" load box might have a position for a capacitors for RF suppression and somehow 100nF has been loaded instead of 1nF!

Dave.

[Guitarking]

Mmm could this be something one could easily change out to fix?

And if I understand correctly from previous posts, the fact that the di signal from my BSS AR133 dulls somewhat when putting the Iron Man as load after the BSS has to do with the fact that every speaker sounds differently? So not using a loadbox but swapping real speakers after the BSS di line out would also yield slightly different results (affects the di signal slightly???)???

[ef37a]

Mmm could this be something one could easily change out to fix?

And if I understand correctly from previous posts, the fact that the di signal from my BSS AR133 dulls somewhat when putting the Iron Man as load after the BSS has to do with the fact that every speaker sounds differently? So not using a loadbox but swapping real speakers after the BSS di line out would also yield slightly different results (affects the di signal slightly???)???

Well, valve gitamps have a high source impedance compared to their hi fi brethren or most solid state amps. This means the sound quality is rather sensitive to the load, its resistive value and inductance so changes in speaker or load values will cause small sound changes...But, in the knockabout world on stage with a drummer, bass, vocals and maybe keys, nobody really hears or gives a ****!

Guitar amplifiers are IMHO not things to be closely scrutinized, more your "ball of chalk and string" rather than digital vernier design process! Some folks even say the sound changes as the winding resistances of the traffs increases as they heat up!

Dave.

[Studio Support Gnome]

Fractal box seems to be working for you.. cool.

for the record , Torpedo CapX has dual outputs and can be configured as Emulated + direct , and it works brilliantly... it can also be configured several other ways, and you can make your Own IR... but seeing as they have factory IR in the store that happen to include four out of 5 of the cabs I have in the room.,.. I can tell you the thing sounds exactly like it would if I mic'ed up the cab... except level attenuated in the room...

But it cannot do 100% attenuation.... just "jolly quiet" and it MUST be connected to the cab.... and the cab must be the correct impedance for the unit

I also have the Captor8 , it works pretty well. , I'm not anal enough to have sample accurately aligned the two using the same cab impulse and seen how good the phase cancellation might be,.... there's a couple of analogue emulations on it and I sometimes use one of those, or sometimes I use the Torpedo Wall of sound plug in, which has the same cab models as the captor X does to match the cab.

my basic prerequisite is ... does it work ? answer yes,
Does it sound good doing it ? answer also , yes

My technique is to use captor X and captor 8 together, and produce what might best be described as an M/S feed , using stereo configuration of captorX for the S and captor 8 as the M . Captor 8 is fed from my Laney IRT studio (valve) , and the Captor X from my Laney IRT60H . Using Laney Heritage 4x12 Cab model and IRT 2x12 cab model.... since that's pretty much what I actually have in the room with me....

sounds bloody great

I also have a couple of Mic's rigged , mostly to remind me how good the captorX really is.....

[Guitarking]

Hello everyone,

Ressurrecting this thread...
Still looking for a way to have the best possible line-out signal from my tube amps to work with my own IR's in my DAW.

So far, I found that the best way for this is to use a real speaker connected to my amps. Line out is provided by the AR-133 DI box (speaker is connected via the link output). The speaker is in my diy isobox. This isobox attentuates pretty well, but the low end still comes through. The latter I want to improve on.

I have a few ideas:
-put an extra isocab in the isocab, to make it even quieter. The sound in the isocab is not important, it's just used as a 'load'.
-buy a loadbox. I'm thinking of the X-load LB2. Apparently this line out is very neutral.
-buying the Celestion Peacekeeper and put it in my isobox. But: will the peacekeeper, like most loadboxes, dull my line out signal? Or is it a different technique from loadboxes/attenuators because it is an actual speaker?

Curious what you think!

[ef37a]

FYI I used a 1/2kW resistive load to test and specc' out valve amps up to 200W (8 Ohms).

That had an analogue mV meter across it which had a top range IIRC of 1kV but making a resistive attenuator to bring the voltage down to line level is beer into water and will do nothing to alter the frequency response. 50W into 8R is 20V rms so you are going to need about 20dB to drop that to +6dBV* or about +8dBu. If you look up the tables to make a "600 Ohm" attenuator you can then use a 600 Ohm line transformer to give earth isolation. OEP traffs have some very suitable, modestly priced units, after all you don't need <<0.1%thd at 20 Hz for guitars!

*Guitar electronicists are you see modern and logical in their measurement parameters!

Dave.

[Hugh Robjohns]

So far, I found that the best way for this is to use a real speaker connected to my amps. Line out is provided by the AR-133 DI box (speaker is connected via the link output).

As a general rule, it's not a great idea to use the link socket when DI-ing an amp/ speaker.

The reason is that a lot of current flows between amp and (low-impedance) speaker. If you plug a DI box into that amp-speaker circuit all that current has to travel between the input and link socket terminals, usually via thin PCB tracks inside the DI box — and they are rarely up to the job!

It's much better, therefore, to connect the speaker directly to the amp, and then use either a duplicate speaker output socket on the amp, or an extension (parallel) socket on the speaker cab itself, to derive a feed for the DI box.

In this way the DI box still sees the full amp signal, but doesn't have to pass any current and is therefore at much less risk of bursting into flames!

You'll need 40dB of input attenuation selected on the DI box input pad because of the very high voltages at the amp output.

[Wonks]

The Celestion Peacekeeper sounds just like a standard speaker. There was a That Pedal Show episode on it. Although they thought it didn't sound as good in the studio (because it was quieter, and 'louder is better'), the level matched mic recordings sounded very close indeed to the standard Celestion used for comparison (they should have listened to the recordings before passing judgement).

It's not a load box, just a speaker designed to be inefficient. Or more inefficient than a standard speaker is. But as that's only 3%-4% efficient anyway, the extra heat output from it will be minimal.

[Wonks]

But any isobox isn't designed to be used for hours on end with lots of power going through it. The acoustic isolation also provides good thermal insulation, so with 50W-100W of power, all but that escaping as weak sound being converted to heat, the heat will quickly build up. Not good for the speaker, and not great for any mic used inside it.

If the isobox is sitting directly on the floor, it's worth trying it out raised up (manually for testing) to see if the bass level drops. If that works, there are foam mats you can get for putting bass cabs on, which might improve things. Or make a wooden frame and suspend it on steel springs.

[Guitarking]

Tnx!

@Hugh, I always have the 40dB pad engaged on my DI. Seems to work fine for years now. If I recall correctly, the manual of the AR-133 states that it is possible this way, but of course with the 40dB pad engaged.
Do you still stink it's unsafe this way and?
And if so, how would I get a line level? Could I, for example, just plug the DI into the second output of my amp (without having to change the ohm?). Or how to get the line from the speaker, I don't want the sound of the speaker, as I'm using IR's.

@Wonks, the isocab is on wheels. But I like your idea of extra suspension.

[Guitarking]

Can anyone confirm the neutral quality of the Fractal Load Box (in silent mode)? As I said at the beginning of this thread, my experience (and what I read) is that once the load/attenuater kicks in, the line-out signal becomes dull. I want a full/neutral line-out signal to send to my daw, but also a proper load to my tube amp of course.

And also, is it not available anymore in Europe?

[Hugh Robjohns]

Seems to work fine for years now.

A 100W into 8 ohms is about 3.5 amps. Jack sockets are typically rated at either 5 or 1 amp. But its the pcb tracks that are the potential weak points... depending on the construction.

And, obviously, lower powered amps involve less current flowing to/from the speaker.

If it works for you then fine... carry on.

My caution is because I have seen a DI on fire after being connected that way!

If I recall correctly, the manual of the AR-133 states that it is possible this way

I checked.. and it's rather vague... but the diagram appesrs to show only a single cable going to the DI box!

Do you still stink it's unsafe this way?

Well, if I really had to DI the power amp output I would always connect as I described (assuming the amp/speaker allowed that) in preference to looping the speaker feed through the DI box.

But I can't remember the last time I DI-d a power amp. I typically either mic the speaker, or take a line level feed from the preamp, FX chain output, or raw guitar (or all three!).

And if so, how would I get a line level?

Connecting the DI jox as I described gives exactly the same output as looping the speaker feed through it. In both cases the DI circuitry is sitting in parallel with the amp and speaker, sampling the audio voltage on the line.

The only difference is that my arrangement doesn't ask the DI box to pass all the power to the speaker as well...

Could I, for example, just plug the DI into the second output of my amp (without having to change the ohm?).

Yes, that would be ideal... and the amp won't even notice it's there!

Or how to get the line from the speaker...

Wire a second socket in the speaker cab in parallel with the first, and use that to feed the DI box.

I don't want the sound of the speaker, as I'm using IR's.

In which case, do you really need the amp/speaker at all? It might be easier to DI the output of your FX chain or preamp output...

[Guitarking]

Thank you Hugh.
Yes I do need the amp as I like them and I mainly use non master volume tube amps with no fx.
Max 35w.
And I need the speaker as it is the best sounding load (attenuators and loadboxes dont sound good so far in my experience).

[ef37a]

To enlarge on Hugh's point, a lot of low power <20W transistor guitar amps have a headphone jack fed from the PA and switch the internal speaker off when cans are inserted. Invariably you find over the years that the internal speaker either goes silent or gets low and distorted.
This is due to minute flexing of the PCB over the years leading to a 'dry' joint which then heats up and gets worse, even in some cases burning a hole in the board.

Even the switched jacks in an FX loop can suffer tarnishing and give problems.

Bottom line: if you want to switch speaker levels, use a friggin switch!

Dave.

[Guitarking]

thank you for the warnings.
I've re-routed now and get the line out from a second amp-output instead of the link in de DI.

[Guitarking]

For anyone in the same search as me for how to get a great line out signal and load for your tube amp: this might be interesting:
https://www.youtube.com/watch?v=AR_q297ll5U

Seems like it explains why my Iron Man isn't doing the job for me (although as attenuator it's great!). And that the Fractal Load box is best.

Is this a safe conclusion that the Fractal wouldn't dull my line out signal when in load?

Still doubting whether to buy the Fractal (or Suhr), or keep using my isocab with a Celestion Peacekeeper... The latter is a) 50% cheaper b) available whereas the Fractal is not available now in Europe.

[Guitarking]

I have a silly, seemingly unrelated question, whilst brainstorming on the decoupling idea in the isobox:
How about decoupling the guitarspeaker by hanging it on sturdy elastics. E.g. the elastics go through the mounting holes of the speaker.
Goal is not a great sound in the isobox anymore but rather to get as little sound as possible. Maybe this is achieved by 1) getting rid of the cab in the first place and 2) decoupling the speaker by hanging it.
Is is mandatory for a speaker to be on a baffle? Will a speaker be damaged by not being on a baffle and "floating" in the air?
Inspiration came from Wonks' decoupling idea combined with a video I saw by Johan Segeborn who took a speaker out of the cab.