Aiken's Reactive Dummy Load.

Mike Sch

Member
Messages
16
Mike, you convinced me to try this circuit instead of the real speaker thing! Niw I have to read the whole thread :)
I read a lot of it and its a lot of good stuff, but you don't have to go thru all of it to do a build. So if you want to get started straight away, just focus on the first post that has the schematic, use EARSE inductors and caps (these are the consensus if you sift thru the thread and I can confirm they work/sound great), and ARCOL or similar power resistors, and then read my posts on page 23 about orienting the pieces and avoiding placing ferrous parts like screws close to inductors. And when you buy parts, I suggest also get a 33 ohm 50 watt in addition to the others so you can tame the sizzle if needed or wanted. You're gonna love the box. I'm using Neural DSP for my simulated amps and they're among the very best out there at this point and my real amps thru this box are definitely better.
 
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303_trancer

Member
Messages
11
A bit of history is that people tried the idea you have several decades ago with less than great results which is what led to these types of circuits being developed.
Hi Mike,
Sorry to bother you again. But I was thinking about your remark. When people were trying my approach several decades ago, how did they use that closed box? Back then there were no IRs. So did they use mics inside the box or a DI box? A mic inside the box would offcourse sound very bad. And if they used a DI box, how did they use that signal to let it sound alright without IRs?

I'm not yet convinced that the closed box with real speakers is a worse option than the RL circuit. Maybe I have to build both off them and A/B the results to see for myself. The only thing I'm realy worried about at the moment is heat builup in the closed box. That could be a reason for the speakers to burn out.
 

teemuk

Member
Messages
3,150
What you describe is known as isolation cabinet. The problem is that they are heavy, typically limited in driver selection, do not really isolate sound to whisper levels (though can attenuate some), peak bass, the internal volume does not compare to "free air" where cabinets typically are used, and that they effectively also isolate all heat and therefore easily overheat everything inside them. Like your precious driver. And so on..

You can find these from shops in various forms and the one that personally seems most useful to me is one where you simply place in a standard speaker cab.
 

303_trancer

Member
Messages
11
I want to use 2 6" 50 watt speakers in anti phase in a closed small cabinet that is included in a just bigger box. So the weight will not be so important because I want to use it only at home. And because the 2 speakers are in anti phase, they can be driven hard because most of the sound will eliminate itself due to anti phase.
But you are right about the heat development inside a closed box. This is my biggest concern at the moment. Maybe I can put in a temperature sensor to monitor the temp.
 

Mike Sch

Member
Messages
16
Back then there were no IRs. So did they use mics inside the box or a DI box?
The ones I saw were mic'd.

As for the load box, I'm shocked at just how good this thing sounds with my amps and OwnHammer IR collection. If I ever play live again, I'll never go thru a cab again. May use the cab as an amp stand since its on casters, but signal to house and in ears is going thru this load box and IRs.
 

manitsa7

Member
Messages
3
hi

i want to built the reactive load but im not good at schematics and i wanted to ask if anyone can make a layout for this without the switch for resistive/reactive i will not use resistive so only reactive

thank you
 

InDecember

Member
Messages
23
hi

i want to built the reactive load but im not good at schematics and i wanted to ask if anyone can make a layout for this without the switch for resistive/reactive i will not use resistive so only reactive

thank you
Just leave the switch out of the plan in the first post.

I'm interested in building this as well, but the most difficult part seems to be getting the right components. I tried Mouser but they don't seem to have those winded inductors. Can someone point me to a (European) distributor?
 

manitsa7

Member
Messages
3
Just leave the switch out of the plan in the first post.

I'm interested in building this as well, but the most difficult part seems to be getting the right components. I tried Mouser but they don't seem to have those winded inductors. Can someone point me to a (European) distributor?
banzai
 

Johndh

Member
Messages
399
I think on these circuits, you are best going to places that specialise in loudspeaker parts to find the coils and big cap. They are used in speaker crossovers.
 

ssbb

Member
Messages
1
I finally got around to building a reactive load based on the info here at a few other forums. Not sure how to post photos onto TGP though / upload media. Would be happy to share
 

PeterBregman

Member
Messages
19
Any reason not to use a transformer on line output for balanced operation? Would the impedance of the primary effect the loading much? I'm thinking something like this:

 

Johndh

Member
Messages
399
I reckon the loading is fine. No matter how you set that, the signal to the transformer is through at least the 5k which is plenty high enough to have no effect on tbe amp. Im interested and not sure about whether thd inductance of the tranny will affect the line out tone, and what sort of level range you'll get.
 

PeterBregman

Member
Messages
19
I reckon the loading is fine. No matter how you set that, the signal to the transformer is through at least the 5k which is plenty high enough to have no effect on tbe amp. Im interested and not sure about whether thd inductance of the tranny will affect the line out tone, and what sort of level range you'll get.
The plot looks close enough when I model it with a 40H primary inductance (the Edcor 10K:600 xfmr specs out that way).


Not so sure about the output level - I might have to mess with the resistor/pot ratio to get it in the right range.
 

PeterBregman

Member
Messages
19
I had the tweak the values a bit more.

If anyone is interested in a similar application as I am (direct recording using low-wattage (~5W) amps), these values seems to pass muster in simulation. I attempted to match the impedance curve of a single 8 or 10 inch speaker in an open back cab (think Fender Champ or Princeton). At full-bore, a 5W amp should be putting out a little over 6V into 8 ohms, which should give you right around line-level at the output of the transformer with the pot around halfway.



Here's the plot for those who might be interested:
 




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