Passive FX Loop - can it drive headphone capable pedal?

GlideOn

GlideOn

Active member
I'm looking to install an FX Loop on a Soldano style 1x12 amp/preamp that currently has none.

Basically I want to use headphones for silent practices, but instead of a hugely expensive attenuator with all the bells as and whistles, use instead a dummy load and one of these clever DI/Cab Sim boxes that plug into the FX Loop and have headphones tap:

https://a.aliexpress.com/_msXr96b

https://a.aliexpress.com/_mr2e6tH

I presume the Soldano and it's 4 gain stages is more than enough to have satisfying tones via headphones without the power amp and these DI boxes seem to add some power amp/cab simulation that looks intriguing.

I am already building a 200w 8ohm dummy load box for power amp to stay happy, plugs into output jack instead of speaker.

Would a passive FX, true bypass loop work fine to drive these DI/Headphone boxes?

Or would one of those Buffered FX Loops from Metropolis, Mojotone, Granger work better for driving a DI box?

https://store.metropoulos.net/products/zero-loss-fx-loop-kit

https://www.mojotone.com/Mojotone-D...gtiVKtqmn-2QgF5J2tsHRpdJJdJa-Xwr7b-xbuRmJ1hfN

https://grangeramp.com/product/ultimate-fx-loop-2/

Not looking to make it super expensive, just looking for a clever solution to an age old issue.

I already have a Spark Go amp with headphones tap, but it's nowhere near as satisfying to use.
 
Why dump all of the power into a resistive load if you’re not going to use the power side for the tonal benefits? You’ll lose all of the resonance and presence circuit impacts as well as the sound of the power tubes.

Just grab a suhr reactive load with a headphone output, and if you want IR, just grab the IR version. Does all that you want and you don’t have to modify the amp with a subpar effects loop of any that you’ve mentioned.
 
glpg80 said:
Why dump all of the power into a resistive load if you’re not going to use the power side for the tonal benefits? You’ll lose all of the resonance and presence circuit impacts as well as the sound of the power tubes.

Just grab a suhr reactive load with a headphone output, and if you want IR, just grab the IR version. Does all that you want and you don’t have to modify the amp with a subpar effects loop of any that you’ve mentioned.
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Look again. The Sim box has cab emulation, power tube emulation and resonance to boot. Really the only thing it doesn't do is attenuate the power amp as it is not an attenuator.

It's also not $$$. It's $$. That's hugely important.

Also, I couldn't care less about what the power section is doing so as long as it is safely loaded up and silenced. Never sounded bad with the master volume low either.
 
Yes they’re $$ and not $$$ but you’re going to have to install a buffered loop into your SLO as well.

I don’t think it’s going to sound as good because you’re sending preamp only signals to emulate the power section and dumping the actual power section as well as NFB controls to a resistive load.

Those loops are all based on LND150’s and they do the job but don’t sound all that great to me. Also those loops are intended to be installed between treble and master, not where SLO passive loops are placed, so you’re cutting up more of the amp and modding it in a much more invasive manner. The passive loops would not be enough to drive the emulator without poor noise performance and overall poor clarity.
 
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glpg80 said:
Yes they’re $$ and not $$$ but you’re going to have to install a buffered loop into your SLO as well.

I don’t think it’s going to sound as good because you’re sending preamp only signals to emulate the power section and dumping the actual power section as well as NFB controls to a resistive load.

Those loops are all based on LND150’s and they do the job but don’t all that great to me. Also those loops are intended to be installed between treble and master, not where SLO passive loops are placed, so you’re cutting up more of the amp and modding it in a much more invasive manner. The passive loops would not be enough to drive the emulator without poor noise performance and overall poor clarity.
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I had thought as much, so passive FX Loop is not sufficient.

I wanted to install the Granger FX Loop for pedals anyways as it has leveling trim pots for send and return built-in to the ends of the input jacks and adjust through them via screwdriver. I can easily install the loop in between treble and master via shielded cable, I don't have the restrictions of the PCB it's all PTP style in my amp.

I'm not entirely convinced the NFB and power amp section are that huge a factor though - I have similar issues with LarMar Master Volumes on my other amps, they provide essentially 4 gain stages by incorporating the phase invertor which cancels out the NFB and power amp voicings, but it sounds amazing despite.

I'm thinking a similar scenario would happen here with the dedicated 4 gain stages, hopefully the pedal here as advertised provides a bit of compensatory voicing to make up for these.

Also, I have a Weber Mass 100w attenuator already. It's a rheostat/L Pad old-school type. It does not get silent for practice and it sounds pretty terrible at lower settings. I don't really want more of the same from other boxe$$$.
 
Installing a post PIMV doesn’t cancel out anything involving NFB controls FWIW. They still function and are tapered with the volume as both phases are adjusted at the same time. You still have full control of all controls and functionality.

Even if you installed a different pre phase master that does something entirely different, you’d still have indirect control over the feedback input via direct control of the primary phase input that’s being inverted.

The granger effects loop sounds like a cool idea but rarely would I want to reach for a tool to adjust that on the fly. I prefer George’s and Jason’s where you flip a switch for line or instrument level output and return is 1:1. Headfirst corrects for the send and return ports being backwards on George’s Metroloop one.

I’m not familiar with the Weber mass 100 attenuator, is it transformer based? I’m usually not a fan of those.

Why not just buy a THD hot plate? Even used they aren’t expensive and will do more of what you need with a resistive load.
 
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glpg80 said:
Installing a post PIMV doesn’t cancel out anything involving NFB controls FWIW. They still function and are tapered with the volume as both phases are adjusted at the same time. You still have full control of all controls and functionality.

Even if you installed a different pre phase master that does something entirely different, you’d still have indirect control over the feedback input via direct control of the primary phase input that’s being inverted.

The granger effects loop sounds like a cool idea but rarely would I want to reach for a tool to adjust that on the fly. I prefer George’s and Jason’s where you flip a switch for line or instrument level output and return is 1:1. Headfirst corrects for the send and return ports being backwards on George’s Metroloop one.

I’m not familiar with the Weber mass 100 attenuator, is it transformer based? I’m usually not a fan of those.

Why not just buy a THD hot plate? Even used they aren’t expensive and will do more of what you need with a resistive load.
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The Hotplate is still hundreds of dollars more to do the same thing my Weber is doing, still with no headphone tab or cab emulation.

If anything, I'm more intrigued by the Harley Benton PA-100 which advertises silent load capability and is well under $100 with favorable reviews. That plus the DI box providing tone shaping and headphone tap, seems like a good deal and effective solution.

Also, the argument that you lose the power amp - isn't that what an FX Loop is for? For going into another power amp? For that external power amp in turn to provide extra tone shaping?
 
GlideOn said:
The Hotplate is still hundreds of dollars more to do the same thing my Weber is doing, still with no headphone tab or cab emulation.

If anything, I'm more intrigued by the Harley Benton PA-100 which advertises silent load capability and is well under $100 with favorable reviews. That plus the DI box providing tone shaping and headphone tap, seems like a good deal and effective solution.

Also, the argument that you lose the power amp - isn't that what an FX Loop is for? For going into another power amp? For that external power amp in turn to provide extra tone shaping?
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Buffered effects loop sends are generally used as a preamp out raw sound correct. However many people myself included would prefer a dedicated line out from the secondary of the OT which captures the amp dynamics as a whole and not just the preamp. Then you can slave that sound to as many flat response big power amps as you desire. Everyone knows the OT and power tubes as well as power amp shaping controls have as much of an impact on tone as the preamp does. Many people don’t have dedicated line outs off of the OT so they use reactive load boxes to get it instead since when using the secondary line out you have to have a loadbox or a cab anyway.
 
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If you've already got the Weber, all you need is something like the Suhr Line Level box to take the output of your amp down to feed a headphone box.
Doing the FX loop is a waste of time and money IMO.
 
True, I haven't even though of using a simple Line Out!

Is the dedicated OT Line Out different than what would be present on an attenuator? Or would it be better to do from the amp like this diagram?:


1000071009.png



Also, the Suhr Load Box just seems the more expensive version of the one I posted in post #1.

I default to being a cheap bastard, so unless it's an absolute one-of-a kind thing that does like no other, I tend to get sticker shock at some of these niche items that have the "name" attached to their piecetag$

Also, the law of averages dictates there are always some quality Chinese built version of that very item 🤣
 
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Let's entertain the very feasible (and affordable) possibility of using the Harley Benton PA-100 attenuator & dummy load box:
https://www.thomannmusic.com/harley...-Yx1Wgp4b7bGh1UGRvWiXqw_cbuTrVzIaApbmEALw_wcB

And combine with the Leeky DI SIM:
https://a.aliexpress.com/_mLy4QFD

It's total around $160, gets me attenuator I can use at whatever level I chose + silent practice, the DI box gets me headphone tap for silent practice and ability to like out a very polished sound for recording to interface and PC DAW for editing.

Does this seem a feasible solution?

The amp is housed inside a reused Mesa MK4 1x12 combo with the reverb pan removed, so I can easily keep these pieces of gear concealed inside as a bonus.
 
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