4 ohm vs 8 ohm speakers with tube amplifiers

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rushfan71

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4 ohm vs 8 ohm speakers with tube amplifiers
« on: 17 Jul 2019, 02:06 pm »
Im currently looking for a new pair of speakers and I have a Primaluna Dialogue Premium HP power amp. With the stock El34's it puts out 70 watts per channel. I would like opinions on 4 vs 8 ohm as the speakers Im looking at are available either way. They are on the higher sensitivity side which I understand is a positive for tube amps.
My main concern is whether or not one type or the other would rob the sound of any bass, soundstage, or detail ect.
Thanks in advance, John




Tyson

Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #1 on: 17 Jul 2019, 03:24 pm »
More than sensitivity, you need to know the impedance of the speakers.  Are they nominal 8 ohms, 6 ohms, 4 ohms?  And do they have any large phase swings (most speakers do), so knowing what is the minimum phase will help. 

My general rule of thumb - if the impedance drops to 4 ohms at any point then I tend to use the 4 ohm tap. 

rushfan71

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #2 on: 17 Jul 2019, 04:32 pm »
Tyson, thank you. Im sorry if I wasn't totally clear. That is what Im asking. The speakers are available in 4 ohm and 8 ohm versions. Which is the better option? Also Im glad you mentioned the speaker outputs on the amplifier. I have 4,8, and 16 ohm taps. Which should I use and why? Ive tried them all. I notice hardly any difference.

Tyson

Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #3 on: 17 Jul 2019, 04:47 pm »
IME, 8 ohms is usually an easier load for tube amps.

Freo-1

Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #4 on: 17 Jul 2019, 07:16 pm »

When in doubt, always go for the lower ohm tap (4 ohms).  Many of these speakers seem to have lower impedance curves. 


Even a nominal 8 ohm speaker can have a dip in the impedance curve where it drops down to 3 to 5 ohms at certain frequencies.   

FullRangeMan

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #5 on: 17 Jul 2019, 07:31 pm »
IME, 8 ohms is usually an easier load for tube amps.
+1
Hi John, you should choose the 8 ohms speaker.
So you will allowed use the 8 ohms taps and also the 4 ohms tap in case this speaker have severe impedance drops that usually is the case with complex xovers.

glynnw

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #6 on: 17 Jul 2019, 07:42 pm »
For a while I ran a 4 ohm speaker off an amp designed for 16 ohm speakers.  The amp was running very hot.  I purchased a Speltz autoformer which goes between amp and speaker - I set it to present a 16 ohm load to the amp and the amp ran much cooler.  Just sayin'.

Tyson

Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #7 on: 17 Jul 2019, 07:56 pm »
Tubes prefer speakers that have high impedance.  Definitely get the 8 ohm version of the speaker, not the 4 ohm.

Freo-1

Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #8 on: 17 Jul 2019, 08:07 pm »

Agree with everyone's advice that 8 ohm speakers are an easier load.  The point I'm making is that a lot of speakers tend to hang out in the lower impedance curves.  If you can. see if there is an impedance curve for the speakers available.  As long as it doesn't drop below 6 ohms, no worries for 8 ohms.


BTW, the reason the amps run warmer at 4 ohms is that there is twice the current supplied at 4 ohms to generate the same wattage as 8 ohms.

FullRangeMan

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #9 on: 17 Jul 2019, 08:51 pm »
Worth mention in the hey days of tubes, speakers and OPTs were all 16 ohms, 8 ohms is a modern situation amp builders was forced to accept.
« Last Edit: 18 Jul 2019, 12:52 am by FullRangeMan »

2wo

Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #10 on: 18 Jul 2019, 12:16 am »
Another vote for the 8 ohm option. Are your amps OTL BTW? I thought at least some Primaluna amps were and would like the higher impedance...John

Rusty Jefferson

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #11 on: 18 Jul 2019, 11:32 am »
.....I would like opinions on 4 vs 8 ohm as the speakers Im looking at are available either way.....
This seems unusual. I'm not familiar with speakers that have a variable impedance.  What brand are they?

Another vote for the 8 ohm option. Are your amps OTL BTW? I thought at least some Primaluna amps were and would like the higher impedance...John
Primaluna amplifiers are transformer coupled, not OTL.

rushfan71

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #12 on: 18 Jul 2019, 03:40 pm »
Thanks for all the input guys. I appreciate the collective knowledge.Yes my amplifier is transformer coupled.  Rusty let me clarify, Im looking at Tekton DI's, they are available in 4 ohm and 8 ohm versions upon request.
So Im thinking The route I want to go is 8 ohm speaker and possibly use the 4 ohm tap on the amp incase they dip down lower in impedance from what Ive gathered here.

Tyson

Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #13 on: 18 Jul 2019, 03:54 pm »
Thanks for all the input guys. I appreciate the collective knowledge.Yes my amplifier is transformer coupled.  Rusty let me clarify, Im looking at Tekton DI's, they are available in 4 ohm and 8 ohm versions upon request.
So Im thinking The route I want to go is 8 ohm speaker and possibly use the 4 ohm tap on the amp incase they dip down lower in impedance from what Ive gathered here.

Nailed it.

Rusty Jefferson

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #14 on: 18 Jul 2019, 10:22 pm »
Okay, I just talked to Tekton. They said "buy the 4 ohm speakers unless you're running an 8 watt SET amplifier." They have to use different woofers on the 8 ohm model, and they feel they are inferior to the woofers they use on the 4 ohm model.  With a push/pull amplifier with a 4 ohm tap, buy the 4 ohm model.  Minimum impedance is 4 ohms. You'll be fine with your amp(s).

PDR

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #15 on: 18 Jul 2019, 10:36 pm »
Great thread..... :thumb:

Wind Chaser

Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #16 on: 19 Jul 2019, 12:14 am »
For a while I ran a 4 ohm speaker off an amp designed for 16 ohm speakers.  The amp was running very hot.  I purchased a Speltz autoformer which goes between amp and speaker - I set it to present a 16 ohm load to the amp and the amp ran much cooler.  Just sayin'.

Wish I had kept mine. The least expensive solution is $540 now... http://www.zeroimpedance.com/zeroimpedance_014.htm


FullRangeMan

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #17 on: 19 Jul 2019, 01:55 am »
Okay, I just talked to Tekton. They said "buy the 4 ohm speakers unless you're running an 8 watt SET amplifier." They have to use different woofers on the 8 ohm model, and they feel they are inferior to the woofers they use on the 4 ohm model.  With a push/pull amplifier with a 4 ohm tap, buy the 4 ohm model.  Minimum impedance is 4 ohms. You'll be fine with your amp(s).
This statement are curious, IMO Tekton take a shoot in his foot.
I believe they mean say the 4 ohms version delivery more spl, no more sound quality, unless the 4 and 8 ohms woofers are not the same, a 4 ohms speaker reduce the options to use a tube amp.

FullRangeMan

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #18 on: 19 Jul 2019, 02:04 am »
Wish I had kept mine. The least expensive solution is $540 now... http://www.zeroimpedance.com/zeroimpedance_014.htm
There is no specs in this page on this OPT, do you have any specs as pri/sec impedance?

Rusty Jefferson

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Re: 4 ohm vs 8 ohm speakers with tube amplifiers
« Reply #19 on: 19 Jul 2019, 03:41 am »
This statement are curious, IMO Tekton take a shoot in his foot.
I believe they mean say the 4 ohms version delivery more spl, no more sound quality, unless the 4 and 8 ohms woofers are not the same, a 4 ohms speaker reduce the options to use a tube amp.
The woofers used for the 4ohm version and the 8 ohm version are different.  They have to be to change the impedance.  Tekton said the woofers used in the 4ohm model are preferred, and recommended for all amplifiers except as mentioned, low power SET amps. This is why I earlier stated I was confused about speakers with optional impedance choices.  It requires changing drivers to accomplish. I described the OP's Primaluna amplifier(s) and he (Eric) confirmed the 4ohm version is what he recommends.