Load Box / Ohm equaliser / thingy Question

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JSett
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Load Box / Ohm equaliser / thingy Question

Post by JSett » Fri Aug 26, 2022 11:37 am

I'm probably using the wrong word there but what should I be looking for/is there a thing I can use with my Bassman in-line from the output so it can see its desired 4 ohm load regardless of the cab I'm plugging into? A lot of venues here have house cabs that are Orange, which are 16ohm...too high a mismatch.
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LVC
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Re: Load Box / Ohm equaliser / thingy Question

Post by LVC » Fri Aug 26, 2022 11:57 am

You want an impedance matcher ― something like the Weber Z-Matcher

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Some attenuators double up as impedance matchers too.
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Re: Load Box / Ohm equaliser / thingy Question

Post by JSett » Fri Aug 26, 2022 11:59 am

LVC wrote:
Fri Aug 26, 2022 11:57 am
You want an impedance matcher ― something like the Weber Z-Matcher

Image

Some attenuators double up as impedance matchers too.
That's the ticket. I had a Weber attenuator that had a permanent 8ohm load regardless of cab, didn't know they did a dedicated box.

Thanks!
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Re: Load Box / Ohm equaliser / thingy Question

Post by JSett » Fri Aug 26, 2022 9:05 pm

Ouch, $270 after shipping. Anyone know of a more ubiquitous option?
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Re: Load Box / Ohm equaliser / thingy Question

Post by LVC » Fri Aug 26, 2022 10:08 pm

I've got a Jet City Jettenuator, but I don't think it would be right for you. It attenuates your volume by a significant amount at its lowest setting, which I suspect might be a little too drastic for onstage playing. Also, as an L-pad circuit, it does slightly cut your highs.

I only use it to play my bigger amps in my flat so I don't mind at all as long as it keeps me in good terms with my neighbours.

Both Bugera and Harley Benton make cheaper clones, but AFAIK they have the same shortcomings.
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Re: Load Box / Ohm equaliser / thingy Question

Post by JSett » Fri Aug 26, 2022 10:16 pm

Yeah, I don't really have need for an attenuator anymore. I sold my Weber Mass when I sold all my +100w heads and moved to smaller stuff. It's just the load matching I needed. Not the end of the world, I was just trying to avoid having to lug a cab to shows if I didn't have to 🤣 and the Bassman being 4ohm is a pain. I'll happily run it into an 8, but no higher.

I, like most people, hate spending money on the boring stuff.
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Re: Load Box / Ohm equaliser / thingy Question

Post by MayTheFuzzBeWithYou » Sat Aug 27, 2022 12:14 am

I recently talked to a guy in germany who builds custom attenuators and loadboxes (130-250€ depending if it‘s 50W or 100W) and he told me that a power transformer solution (without volume loss) would be possible too - but way more expensive (3-400€). The Weber sounds about right but yeah I‘m with you with the „boring things“. Haha.

The impedance mismatch and the 120V vs 230V issues are the two things I really dislike about vintage amps (and like about my supersonic).

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Re: Load Box / Ohm equaliser / thingy Question

Post by øøøøøøø » Sat Aug 27, 2022 7:39 am

If you only need to switch one specific impedance to another specific impedance, all you need is a transformer (in a box with an input and output).

You might be able to DIY this bit cheaper than the Weber unit, but probably not, to be honest--after all the shipping of the various parts, and sourcing a quality transformer, etc. you might not come out very far ahead.

If you need (for example) a 2:1 impedance ratio then your turns ratio would be 1.4:1 (the turns ratio will be the square root of the impedance ratio).

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Re: Load Box / Ohm equaliser / thingy Question

Post by JSett » Sat Aug 27, 2022 9:12 am

øøøøøøø wrote:
Sat Aug 27, 2022 7:39 am
If you only need to switch one specific impedance to another specific impedance, all you need is a transformer (in a box with an input and output).

You might be able to DIY this bit cheaper than the Weber unit, but probably not, to be honest--after all the shipping of the various parts, and sourcing a quality transformer, etc. you might not come out very far ahead.

If you need (for example) a 2:1 impedance ratio then your turns ratio would be 1.4:1 (the turns ratio will be the square root of the impedance ratio).
I have been looking into the DIY option and you're right. A good quality transformer that can handle the wattage is pretty expensive. $80 of the cost of the Weber is the insane shipping cost (auto-shipping calculators are always rubbish and wildly out of reality for some reason) in fairness.

I'll likely just stump-up for it. I always rate Weber gear and have used it on and off for years.
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Re: Load Box / Ohm equaliser / thingy Question

Post by DeathJag » Sat Aug 27, 2022 10:21 am

What about taking another 8-ohm speaker and pulling off the cone?!! Seems like it'll be super ugly but would function well? Maybe? Have the empty spider hanging out behind the amp. I mean, doesn't everyone have junky 8 ohm speakers laying around?

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Re: Load Box / Ohm equaliser / thingy Question

Post by MayTheFuzzBeWithYou » Mon Aug 29, 2022 12:17 am

DeathJag wrote:
Sat Aug 27, 2022 10:21 am
What about taking another 8-ohm speaker and pulling off the cone?!! Seems like it'll be super ugly but would function well? Maybe? Have the empty spider hanging out behind the amp. I mean, doesn't everyone have junky 8 ohm speakers laying around?
If your amp has enough outputs you could also get a „multi-purpose“ attenuator/loadbox that you connect instead of the second cab. And use the attenuator additionally for a line out signal or as an actual attenuator if you ever need it. This could be a tad cheaper.

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