Suhr Reactive Load  [schematic]

Tube or solid-state, this section goes to eleven!
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floris
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Post by floris »

The signal from the speaker output of the tube amp is different if it is connected to a reactive load, instead of a resistive load. That is because the tube amp output, which is relatively high impedance compared to transistor amps, "works together with" and is affected by that load. The line out circuit must be connected to the speaker output of the amp (= the same as connecting it to the input of the load box). The reactive load is not bypassed when using this line out, because the tube amp's speaker output signal is affected by this reactive load.
I hope this helps...
Last edited by floris on 08 Jan 2021, 01:22, edited 1 time in total.

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Ampkat
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Post by Ampkat »

Floris thanks for posting with me you pose some interesting scenarios. However I can't tell the difference from the reactive load using line out vs the resistive load line out. The Line out is taken from the 8 ohm tap of the OT and then a voltage divider network. The reactive load is just basically taking the place of a speaker or motor if you will. The line out doesn't react to the reactive load any differently than a resistive load because all the OT sees is a load. Now if you would put a line out after the attenuator it would sound different as a speaker does and you would hear the resonance freaquency differences. I've used both reactive and resistive in the line out situation and can't tell them apart but using the Thru is very different. Maybe my Fletcher Munson curves are off at my older age lol. Anyway
Thanks for posting and I will be back after more research.

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Ampkat
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Post by Ampkat »

Ampkat wrote: 07 Jan 2021, 23:12 Floris thanks for posting with me you pose some interesting scenarios. However I can't tell the difference from the reactive load using line out vs the resistive load line out. The Line out is taken from the 8 ohm tap of the OT and then a voltage divider network. The reactive load is just basically taking the place of a speaker or motor if you will. The line out doesn't react to the reactive load any differently than a resistive load because all the OT sees is a load. Now if you would put a line out after the attenuator it would sound different as a speaker does and you would hear the resonance freaquency differences. I've used both reactive and resistive and a speaker in the line out situation and can't tell them apart but using the Thru is very different. Maybe my Fletcher Munson curves are off at my older age lol. Anyway
Thanks for posting and I will be back after more research.

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floris
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Post by floris »

>"The reactive load is just basically taking the place of a speaker or motor if you will."
Yes, exactly. The reactive load has two purposes:
1) Convert the power of the amp into heat so that the amp does not die.
2) Let the amp behave as it would with a speaker connected.
This results into a different signal at the amp speaker output than with a resistive load, but does not sound like a speaker.

>"The line out doesn't react to the reactive load any differently than a resistive load because all the OT sees is a load."
The tube amp output stage will/should behave differently if it's a reactive v.s. a resistive load.

>"Now if you would put a line out after the attenuator ..."
Where in this reactive load would you put the line-out? It's not an attenuator and had no speaker output.

>"... it would sound different as a speaker does ..."
The reactive load-box will not make it sound like a speaker does. The IR after the line-out will make it sound like a speaker does.

Regards, Floris

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Post by m0rk »

good job! but I guess we are still waiting on that list for the first design of yours :)
any chance??

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Post by karhya »

I think people that are not into audio electronic may not know which kind of capacitor is needed. Electrolytic or film capacitor ?
Also on your last build, you have a funny looking resistor (the 9W 62Ohm). What kind of resistor is it ?
Your output transformer, where did you buy it ? The price goes from very affordable to so expensive. Where is the sweet spot ? Why this one ?
Finally, which brand for the components ? They are so many ^^

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Post by m0rk »

karhya wrote: 12 Jan 2021, 20:27 I think people that are not into audio electronic may not know which kind of capacitor is needed. Electrolytic or film capacitor ?
Also on your last build, you have a funny looking resistor (the 9W 62Ohm). What kind of resistor is it ?
Your output transformer, where did you buy it ? The price goes from very affordable to so expensive. Where is the sweet spot ? Why this one ?
Finally, which brand for the components ? They are so many ^^
So true that...

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