Driving 4ohm Speakers

onelivewire · 2469

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Offline onelivewire

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on: January 06, 2023, 08:47:46 AM
Hey there,

I've been happily driving T1s & Meze Empys on my C4S Sex for a good few years, as well as periods driving my Klipsch Heresys. As I had these speakers in mind when building the SEX, I opted for the 8ohm output impedence when wiring.

However, after a move the Heresys have gone from my office into the living room. I am waiting on a pair of Buchardt S400 MKII's for the office.

I know that the SEX is underpowered for the 89db sensitivity of these speakers and it is not my long-term plan for driving them. However, in the short-term, the amp is already in my office, so I'd like to use it for low-volume listening for now. I have a couple questions with regard to this use case.

1) I understand there will be an additional drop in volume when rewiring output to 4ohm that is also associated with reduced bass output. Obviously this is not ideal, but assuming the resulting volume is reasonable for an interim period, are there any other lookouts for impact to headphone function, for example?
2) Is there any risk in (initially) running these 4ohm speakers with 8ohm output wiring as I rearrange the room, or need I prioritize rewiring prior to testing the speakers with the SEX?

Thanks in advance!



Offline Doc B.

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Reply #1 on: January 06, 2023, 10:35:11 AM
You can run 4 ohm speakers off the 8 ohm setup with no problem other than the bass might not sound its very best. Bass output will not particularly decrease when you change from 8 ohms to 4 ohms with 4 ohm speakers. In theory bass should get a little tighter and have a little more flat response when you run 4 ohm speakers from the 4 ohm tap. Running headphones off the 4 ohm setup is actually preferred to 8 ohms because it can lower the noise floor a bit.

Dan "Doc B." Schmalle
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Bottlehead Corp.


Offline onelivewire

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Reply #2 on: January 06, 2023, 11:37:53 AM
Perfect, thanks for confirming, Doc!



Offline onelivewire

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Reply #3 on: January 22, 2023, 09:28:27 AM
Circling back here after making the change... I expected a subtle difference, but I'm finding it noticeable without extreme focus on the music. Both on the speakers and headphones I find basslines that washed into the background now cut through clearly and kick drums are more present.

It may take some getting used to on the headphones, but I love the improvement for the bookshelves.

Thanks again for the help here!



Offline jufelling

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Reply #4 on: February 08, 2023, 09:38:48 PM
You can run 4 ohm speakers off the 8 ohm setup with no problem other than the bass might not sound its very best. Bass output will not particularly decrease when you change from 8 ohms to 4 ohms with 4 ohm speakers. In theory bass should get a little tighter and have a little more flat response when you run 4 ohm speakers from the 4 ohm tap. Running headphones off the 4 ohm setup is actually preferred to 8 ohms because it can lower the noise floor a bit.

That is a great info, thanks Doc!
I've also wired my amp for 8 ohm and therefore never tried my 4 ohm Canton Karat 930 speakers because I had the fear to blow up the amp.
I searched the internet if I could try it anyway and always were told that you should never drive 4 ohm speaker with an 8 ohm amp unless you want to damage the amp.



Offline Paul Birkeland

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Reply #5 on: February 09, 2023, 04:12:33 AM
you should never drive 4 ohm speaker with an 8 ohm amp unless you want to damage the amp.
You could hook up a 1 ohm speaker with the SEX amp wired for 8 ohms and it's not going to blow up.

Solid state amplifiers are a different matter entirely!

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline jufelling

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Reply #6 on: February 15, 2023, 09:23:49 PM
Okay cool. Thank you!

In the meantime I connected the speakers to the amp and it sounds ok.

I also ordered Blumenstein Orca a few month ago which should arrive soon.
These ones are 8 ohm speakers and the reason why I wired the amp for 8 ohm in the first place.

Just for understanding: It's best to run these speakers with the 8 ohm wiring, right? They wouldnt benefit from 4 ohm like headphones (e.g. lower noise floor)?
Soon also a pair of Sennheiser HD660S2 (300 ohm) will arrive.

==> Should I keep the 8 ohm wiring?



Offline Paul Birkeland

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Reply #7 on: February 16, 2023, 04:09:08 AM
The Orca isn't sensitive enough to benefit from a lower noise floor, so 8 ohms would be the way to go.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man