4 ohm tap vs 8 ohm tap

At the 4 ohm tap, you would be running the signal through more transformer windings than at the 8 or 16 ohm tap. The 2 ohm tap (if you have one) would go thru even more output transformer windings. And all things being equal (and they never are) more wire yields a more degraded signal. How much? depends on if the better damping factor is worth the (small) loss in signal quality.

Also the amp may sound different into the different impedance taps. IT may not "sound right" using a 2 or 4 ohm tap with you speakers. things may sound better with the 8. Or with the four. use your ears. depends on what low impedance dips your speakers have.

Aroc,

You have received incorrect info. No matter which tap you use, the full primary of the output transformer is used, and on the secondary, the HIGHER the tap impedance, the MORE of the winding is used (for example, on an winding with 4, 8 & 16 ohm taps, the 4 ohm tap is the CENTER TAP).

Another thing--according to the Dynaco ST-70 manual, running an 8 ohm speaker on a four ohm tap reduces power, but "the operating conditions are shifted from maximum power output to minimum distortion."

And, yes, the damping factor will be higher from the lower tap. The great thing is that it costs nothing to find out which way sounds better, and will not damage your amp (if you turn off the amp before playing with the wiring). Luceeeee, you got some listening to do!

BTW, I am the designer of a tube power amp, and have been an electronic technician for over 30 years.

Hi Al. I would suggest listening to Al. He and I discussed this very same topic quiet some time ago. My speakers, Roman Audio Centurions are an 8-ohm rated speaker and I am running them on the 4 ohm taps on my tube amp. At first I didn't think there there would be a difference, but Al was right, there is. Try it and see for youself.

SHAMELESS PLUG: Al does make a really awesome tube amp, I use one.

Aroc,

Alraul is correct - the full primary winding is always seen
by the output tubes.

The different taps are on the secondary side of the the
transformer with higher tap impedance having more windings.

Hence the 4 ohm tap will have the fewest windings of the
set of 4, 8, and 16 ohm taps.

Dr. Gregory Greenman
Physicist

Thanks for the corrections Al. I did a quick internet search and you are right on the money. Thanks again. Gotta watch who you get advise from!

Thanks, I just wanted to make sure there were no issues before I started running them like that for an extended period of time. I tried the 4ohm tap and I felt I liked it beeter that way.
Thanks again. Scott

Well, I can definatly notice a difference. I just got these speakers about a week and a half ago. When I first hooked them up I forgot to change from 4 to 6 ohm because my Thiels are 4 ohm. I liked the speakers right away.
After I noticed that I forgot to change to the 8 ohm tap, I quickly changed the amps to the 8 ohm tap.
After a few LP's I began to not hear the bass. So after you all confirmed that I would not damage anything, I switched back to the 4 ohm tao. The bass is back.
You need all the help you can get with the Shearwaters. They are not bass heavey at all.
Thanks, Scott

Aroc,

"Thanks for the corrections Al. I did a quick internet search and you are right on the money. Thanks again. Gotta watch who you get advise from!"

You just pinpointed why I ended my post (giving advice) with my qualifications. I notice Morbius subscribes to this concept, too!

Alraul,

I do end my post with my qualifications - and I get a lot
of flak for doing so.

The qualifications work as a double-edged sword.

The fact that I put "Physicist" after my name says that I
do have a special expertise in Physics. It also says that
I have absolutely no special qualifications in anything else.

Dr. Gregory Greenman
Physicist

Morbius, I think you will find this amusing
I have spoke to a good work friend who is an electrical engineer. He has been in this profession for over 25 years.
I was telling him about the discussion on the CABLE forum of breaking in power cords. I almost had to call a code red to get him medical attention, because he couldn't stop laughing so hard.
How anal is this crap?

Would like to add that this has been a useful thread for me. I am running a pair of Granite Audio 860.1 tubed monoblocks into Equation 25 speakers and had been using the 8 ohm tap- never gave it much thought. The speakers are 6 ohm. Tried the 4 ohm last night and was very pleasantly surprised- cleaner, more articulate bass, and warmer midrange, without losing too much on top- just the effect I have been looking for with mixed success by trying different cabling.

Are there any technical reasons that a 6 ohm speaker should be driven better with a 4 ohm than a 8 ohm amp?

Makes me wonder about the Proacs that I sold because I was unhappy with them. Wonder how they would have sounded with the 4 ohm tap.

Of course the output tubes are always connected to the full primary winding of the transformer. So everyone is talking about the secondary windings, 4 vs 8 ohms. However, when you put an 8ohm load on the 4 ohm tap (or 4 on 8) you have changed the impedance loading on the output tubes, even though you never moved their wires. This probably affects the operating characteristics of the tubes.

No taps on my Crown PS-200s. The spec sheet says it supports 4, 8 and 16 ohm impedance. 170 wpc at 4 ohm, 100 wpc at 8 ohm, 55 wpc at 16 ohm - max average at 0.1% THD. Just swapped in a lovely pair of new Wharfedate Liniton Heritage Speakers listed at nominal 6 ohm, dipping to just under 4 ohm.

Still breaking in the speakers but they seem to sound best with the Crown at full attenuation, unpowered Shitt preamp with the input pot about 50% and system volume controlled by the DAC streamer input level. The Lintons are 3-way double rear ported, warm and rich with a wide dispersion range. The '70s called, they want their throwback box speakers back :)

Nice  18 yr old thread revival…..

FWIW I tried the 4 OHM taps on my setup and although my speakers are rated as "8 ohm compatible" and are more like 4 ohm nominal. I felt they were a bit constrained on the 4 ohm tap and soundstage shrunk a bit. That surprised me.

 

After a few LP's I began to not hear the bass. So after you all confirmed that I would not damage anything, I switched back to the 4 ohm tao. The bass is back.

The suspension of any loudspeaker takes a while to break in. You might try the 8 Ohm taps again in a few weeks and see if the bass is still missing. The 8 Ohm tap is more efficient by a few Watts, depending on the output power the amp is capable of. That in itself isn't a big deal.

The load on the power tubes is much higher if the 4 Ohm tap is used on an 8 Ohm speaker. This might mean less power from the amp, but might also mean less distortion (less distortion = greater transparency). So its always worth trying.