Age Old Question - 4 or 8 ohm tap?

[AFpay]

Greetings,

I am currently running my Deftech 3000's off of the 8 ohm amp tap. The speakers are 8 ohms but, I often hear that there is an advantage to running them at 4 ohms. My amps are Rogue 150's. Any thoughts or experiences out there that I can learn from? What, if any, advantage is there to running 8 ohm speakers from the amps 4 ohm taps?

Thanks,

AFpay

 

[markn2wae]

Amp. may like a slightly lighter load?

I have heard someplace that some tube amps may sound better with a slightly lighter load than what is considered "normal.

If the speaker "spends a lot more time" below 8 Ohms across the audio range, you may find it performs better as a system (amp. and speaker) than when hooked to the 8 Ohm tap.:scratch2:

Mark T.

 

[Tom Bavis]

Speaker damping will be greater on the 4 Ohm tap - but whether that sounds better or worse will depend on the speaker. The most power will available on the "matched" tap, but if you don't need every last watt, that may not matter.

 

[AFpay]

Thanks for the replies,

I think that the Deftechs probably need all the power that they can get. They have a powered sub built into them so at the very least the amp does not have to control the bass driver. They are supposed to be able to handle 1000 watts, that is why I think that they are power hungry. I will give the 4 Ohm tap a listen and see if I can tell the difference.

AF

 

[Kegger]

You also change the load the TUBE sees on the input side of the trannie
by using different load speakers on different load taps, so some speakers
and or amps for that matter may prefer being or having on a different tap.

So yes by all means you should experiment and see.

If you had a trannie that was 6600 pt to pt which is good for say 6l6's, now
you put say a firm 8ohm load on the 4ohm tap, that trannie may well be good
for an EL84 based amp now and be smiling all the way at it's lower power use.
So there is a lot of experimenting that can be done with possable great results. (or not so great results)

 

[PakProtector]

You also change the load the TUBE sees on the input side of the trannie
by using different load speakers on different load taps, so some speakers
and or amps for that matter may prefer being or having on a different tap.

Hey-Hey!!!,
The primary load on a TX cupled circuit is entirely dependant on the load applied to the secondary. It is all about turns ratio betwen the two. So, applying an 8R load to the 4R tap would in theory double the load the power tube sees( and by theory, I mean part of The theory ). If it is supposed to be 3k plate-to-plate, you would be looking at 6k instead...

The frequency respoponse at LF is set by the primary inductance, and its relatioship to the load it is trying to apply. If you try to apply twice the load, and don't double the primary L, the turn-over frequency ( where 2PiFL=Plate load ) doubles.
cheers,
Douglas

 

[jaymanaa]

I heard this too, and tried the 4ohm taps on my Dynaco 70 with some Heresys (not power hungry). For whatever reason it sounded terrible:thumbsdn: Let us know how your experiment works out. Jay

 

[jgarcia]

i read somewhere that a set of yammy 1000-m's were ran on the 4 ohm side of a tube amp and the speakers sounded better. i wanted to try this, but my tube amp is low in watts and do not want to damage anything. so i am curious as well.

regards, j garcia

 

[AFpay]

Ok, so I have moved over to the 4 ohm tap. I wish I could say that there was a dramatic improvement, but I can't. There seems to be a little more bass but overall the presentation seems the same. Keep in mind these are just first impressions. I'll have to listen more and live with the 4 Ohm setup to see if it really makes a difference.

By the way, the system sounded good to my ears on the 8 Ohm tap. I'm just trying to find a way to squeeze a little more out of it.

AFpay

 

[Kegger]

Experiment as you will, won't hurt anything, power output is changed but a little.