4 ohm (or 6) Bookshelf speakers. Pass Labs 30.8


Hi everyone!

I am having a hard time finding book shelf speakers that run in 4 ohm (or 6 maybe?).  Before I seriously consider the Pass Labs 30.8, I need to at least know what kind of speakers to listen to, price them out, etc.  I am just now building a system and have no speakers, but I see it looks like the 30.8 is ideal for not that many speakers (from what I can see).  Google didn't help much. I live in an apartment, and the room I have isn't ideal for floor speakers, and is perfect for a lower watt amp, I'd rather pay for quality over power I won't use!.  Bass from floor speakers could also be an issue so I'd rather not even entertain that idea.   If 4 ohm and small speaker don't really go together, I will consider the 150.8 instead.  

Many have said "Any 4 ohm speaker", but being able to find a 4ohm book shelf has left me with not much, so far. 

If this isn't really in the cards (small speakers and 4ohm), feel free to be blunt.  Save me time.  :)

So here is what I have found so far.  Any others?  

1.  Harberth Super HL

Thanks everyone in advance.
823f81fb dd0d 4022 bd2f d903a8e26e2cmplstereo

Showing 2 responses by almarg

First, regarding...

... is a speaker with sensitivity of 100 at 8 ohms as loud per watt as a speaker of sensitivity 85 at 4 ohms?

If the specs are accurate (and speaker sensitivity and efficiency specs are often optimistic by a few db), and if the specs are defined on a per watt basis, an 85 db 8 ohm speaker will be equally as loud as an 85 db 4 ohm speaker, for a given input power. A 100 db 8 ohm speaker would be **vastly** louder than both of them, for a given input power.

However, such specs are most often defined on the basis of an input of 2.83 volts, rather than 1 watt.

2.83 volts into 8 ohms corresponds to 1 watt; 2.83 volts into 4 ohms corresponds to 2 watts. 2 watts is 3 db greater than 1 watt. Therefore an 85 db/2.83 volt/1 meter 4 ohm speaker corresponds to only 82 db/1 watt/1 meter, while an 85 db/2.83 volt/1 meter 8 ohm speaker corresponds to 85 db/1 watt/1 meter.

In that situation, **if** the amplifier is capable of providing twice as much power into 4 ohms as into 8 ohms the maximum volume it will be able to produce with the 4 ohm 85 db/2.83 volt speakers will be exactly the same as the maximum volume it can produce with the 8 ohm 85 db/2.83 volt speakers. Again, assuming the specs are accurate.

Second, you may find it informative to plug some numbers into this calculator:

https://myhometheater.homestead.com/splcalculator.html

You’ll find that under conservative assumptions about placement 30 watts into a pair of 85 db/1 watt/1 meter speakers will result in a sound pressure level of 93 db at a distance of 10 feet. Less conservative assumptions will increase that volume by an additional few db. And doubling that power to 60 watts will only result in a 3 db increase.

Given your preference for "lower listening volumes up to moderate," and the fact that you are in an apartment, I would expect that you would exceed 93 db at the listening position very rarely, and then only on very brief and very occasional dynamic peaks on certain recordings. Consequently, when and if that were to happen a correspondingly brief excursion into class AB seems to me to be almost certain to be unnoticeable.

Given all of that I would strongly recommend that you put aside your stated preference for a 4 ohm speaker. And as you realize doing so would greatly expand the range of available choices.

Also, you may find this paper by Nelson Pass to be of interest, if you haven’t already seen it:

https://www.passlabs.com/press/leaving-class

Good luck. Regards,
-- Al


Or at least I am not doubling my volume like I thought I would be.

A generally recognized rule of thumb guideline is that achieving a subjective perception of "twice as loud" requires either a 10 db increase in speaker sensitivity or a 10 db increase in the amount of power delivered to the speaker (assuming the speaker can comfortably handle that amount of power). A 10 db increase in power means 10 times as many watts.

Good luck. Regards,
-- Al