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

I’m running the Buchardt S400’s with a Pass xa30.8 and they sound amazing!  You won’t be disappointed.

I recommend you take a look at Ascend Acoustics Sierra 2 and Sierra 2 EX. Either of these would work great in your apartment and at the listening levels you describe.

@mplstereo ATC

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

@almarg 

WOW.  So as far 4 ohm/ 8 ohm, im not getting "louder" (for this specific set up), presuming the sensitivity is the same.   Or at least I am not doubling my volume like I thought I would be. That explains some of the responses that I didn't understand.But, increasing sensitivity is the key to getting a bit more volume out of a speaker, not dropping to 4 ohm.  Now this is making a lot more sense, I was having a hard time understanding why such an amp would only play nice in class A with so few book shelf speakers. That was extremely helpful.  

I used the calculator, 30w at a sensitivity of 85 is plenty loud for me, as loud as I'd ever really want to go it seems, in my given room.

Looks like I have much less to focus on that I thought, and will restart my speaker search to include 8 ohm.  I knew some used 8 ohm but just figured it was because thats what they had, and said it worked just fine. I presumed they were in A/B mode then.   

Point noted and advice taken.  

@jaybe 

" I’ve run a 30.5 through an AR pre to 8 ohm 86db sensitivity speakers in a fairly small room. No problem at all with volume to pretty loud levels. I don’t believe it ever got out of class A but have no way of verifying that. Pass will also tell you that there is no sudden change in sound when it goes to A/B. If mine ever changed to A/B I didn’t know it. This 30 watt amp was tested long ago by Stereophile to output about 150 watts I believe, which is slightly higher than the .8 model."

Thats helpful to know, and even surprising!  Great to hear from some one that owns the xa30.  8 ohms and 86.  Well, sounds like I am being a little to careful here.  Just curious, what make/model of speakers?  

Thanks!

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

@stttt Those look good, thanks!  Added to list!

@yogiboy 

" The Aerial 5t is a 4 ohm speaker. BTW, why do you feel that you need a 4 ohm speaker? The impedance changes with most speakers!"

Ok, well, I don't know anything about impedance changing.  Not that I needed another variable in the mix, but if it's there, it's there!  One thing I did not clarify earlier on because I was still learning, was that I want to stay with in the amps Class  A rating, and at 8 ohms, that is only 30w/ch.  By going with a 4 ohm speaker (as in, only 4 ohm), the amp is now making (advertised) 60w/ch, fully class A. 

So I guess in short, my answer is volume and headroom.  How much of that I'll need depends on the speaker and likely the source, too. Though my listening levels will tend to be low, sometimes moderate, I can appreciate knowing that I have some flexibility there.  60w/ch still isn't a lot, most amps today make 100/ch. 

One thing thats hard to pin, is what is the minimum wattage any speaker needs to sound full or at it's potential.  That varies with speakers, and I don't know how to validate what power they need minimum.  Maybe most book shelfs only need 10 watts to sound good?  Others, more?  And thats where sensitivity comes into play.  Most book shelf speakers, or stand mounts, seem to be rated 85-86.  Not helpful with low output amps.  95 would be a different story, etc.  But I seem to be finding more and more 4 ohm speakers,not so much highly sensitive ones.  I do know Klipsch makes some, though.  So, that said, I'm also open to highly sensitive speakers, I just don't know at what sensitivity level they are on par with twice the volume, which would only be needed as a reference point so I could calculate other sensitivity figures, too.  

I’ve run a 30.5 through an AR pre to 8 ohm 86db sensitivity speakers in a fairly small room. No problem at all with volume to pretty loud levels. I don’t believe it ever got out of class A but have no way of verifying that. Pass will also tell you that there is no sudden change in sound when it goes to A/B. If mine ever changed to A/B I didn’t know it. This 30 watt amp was tested long ago by Stereophile to output about 150 watts I believe, which is slightly higher than the .8 model.

@jsautter   Thanks for the input!  Just to make sure we are on teh same page, my goal is to keep the amp running in class A for my listening needs.  at 8 ohms, it produces 30w/ch.  at 4 ohms it produces 60w/ch.  So, there is more headroom fro Class A, making it a bit more practical for when/if I want to go a bit louder, though I do prefer lower volumes.  60w/ch isn't much though in a world of massive mono blocks!  Should be fine for me though.  

When you say "perform better in 8 ohms", what do you mean?  

Once I can validate a speaker will very likely produce the volumes I am seeking, I'll add it to the list of speakers to listen too.  An 8 ohm speaker at a sensitivity of 86 will likely not be ideal, for example.  I want to give the amp a chance, and have to be selective in the speaker to do so.  

@georgehifi   Agreed, that is what I am shooting for.  Just, not a boat load of 4/6 ohm shelf speakers out there, but they are out there, and increasingly enough it seems I have enough options to consider this amp as something for me (where as before I was concerned there just wasn't a selection of 4 ohm speakers in the shelf form).  Do you think very sensitive speaker, say 95 or higher @8ohm, would be just as good or better than a speakers sensitivity at 85 with 4 ohm?  Do you have a preference?  Just curious, seems like both methods might get the same result, just different ways.  Thanks!

I'm selling my Selah Tempestas. They are 6ohm. Yo can see them in my burial systems.
Raal, Accuton and Scanspeak drivers.

@stereo5   Yea, I hear ya there!  I am doing my best to be realistic with the right speaker, trust me.  I may go up to $2500 new/used.  That's pretty significant, but so is the amp.  Due to cost, the purchasing will be over a time frame, and reflect goods sold from my home.  :)  Most importantly I just want speakers that, at a minimum, will remain in the amps Class A range to my common listening levels and not switch over to A/B all the time, eliminating the heart of the amp, sort to speak.  I have read, however, this speaker, the s400, doesn't perform well at lower volumes and needs moderate volume to sound full.  Could still try it, but if the two reviewers that stated that are right, it's not for me.  Will seek more insight from owners.  Thanks for your input!

@razorbraun Thanks!  That speaker is now on my short list.  How do they sound at lower volumes?  The limited reviews I came across noted that to sound full they had to be "pushed" a little, or turned up.  I'm seeking speakers for low to moderate listing volumes, and if this is true, the 400's may not be right for me.  I want this speaker to be right for me though, and might just try it!  Thanks!

@ostrey93 Those speakers look like good ones, too.  Do you think they might not be up to par with the amp?  I only say this because of the sweeping cost difference between the amp and speaker, and it may not matter that much.  Also, how do the speakers sound at lower volumes?  I know some need to be pushed just a bit to sound good, according to some, and am seeking a speaker that does well at lower volumes  Not any easy task, but some speakers do it better than others.  Bass is not that critical, bass presence is, but full sound at lower volumes is what I am really seeking.  Thanks!   

@jaybe I emailed them, and Kent was helpful with providing a lot of information on how to determine what was best for my set up, but did not mention specific speakers, except one that was to expensive ($13k/pr).  I was hoping by now, I would have an idea of what would work well for me, and have a base of dozens of speakers, and go from there.  

Many have mentioned here, as supported in a stereophile review, that the amps lower output is not a big deal, because it goes into A/B after 30/w and will go up to 100/w or more.  And so for that reason, I should be less concerned about ohms/sensitivity.  Well, if that is the case, and I'm running in A/B most the time for my listening, what was the point in getting an amp for it's A class properties?  And I can't really know how loud a certain any speaker will be until it's in my room.  (why the variables are important)

This is certainly one reason I'v been looking at 4 ohm speakers, to take advantage of the power bump from the amp (up to 60w/ch), which opens up a lot more options and leaves me feeling a bit more confident the amp will remain in class A.  I do prefer lower listening volumes up to moderate, but still want to err on the safe side leaving my self plenty of room in A class (plenty being relative, I know this isn't a mono block), using A/B when I'm more in the mood for loud music and won't care so much for the sound as I would in a quiet mood.  (personal preference)

I feel that the xa30.8 is still a  good candidate given my listening room is small and my preference of lower volume listening, but don't want to pigeon hole my self with a high end amp and only lower volumes in class A.  If this isn't the right setting for it, what is?  Another area of struggle for me when learning/reviewing speakers is ohms vs sensitivity. I'v read a lot and am getting much better at understanding, still hazy.  If 4 ohms bumps up the power, to 60w/ch and sensitivity means more volume with less power (sort of), where do they equal?  Meaning, is a speaker with sensitivity of 100 at 8 ohms as loud per watt as a speaker of sensitivity 85 at 4 ohms? 

The mission here isn't for me to quibble to much over the numbers (which I am because I'm not an expert), but rather, find the right threshold, single those speakers out, then I can listen them, with confidence, knowing they will work for my set up, not wasting time on speakers that certainly won't. Keeping the amp in full class A up to and at moderate listening volumes is the goal.  A few examples here that were listed were some 4 and 6 ohm speakers, all with low sensitivity though. (and why can't we have sensitive 4 ohms?)  Then there are 8 ohm speakers with high sensitivity.  They may all work well.  

This is much more important when buying used speakers that I can't listen too.  Some I can audition right here in my home and plan on doing so after I get the amp, but, I still need to make sure that the amp it self isn't so limited with speakers that will allow full class A with moderate listening volumes, that is the tricky part.  It's looking a lot better for me and this amp, but still concerned it's class A properties may be a bit limited (and that might be ok, I don't need every speaker option).  
  

Call Pass. They'll give you a list of speakers. They did that for me.

Thank you everyone for your help, I will be looking into these speakers!  It's great to hear from everyone that has them and can speak for them and also clear up some confusion I had about the amp.  Seems pretty consistent, regardless what I do, buy good speakers and son't cheap out!  That's ok, that just means I'll have to sell some items and save longer, but hey, for an end all Hi-Fi (as long as it lasts), buy once cry once.  Thanks again everyone.  

Dynaudio Contour 20 is really good but its a pretty big monitor and very current hungry. For something smaller and a little less demanding I'd be all over some Dynaudio Special 40. 

I also own the Buchardt S400s.   Right now using my Anthem MRX 720 as my amp... they sound quite good.  Sometimes exceptional, amazing bass for a bookshelf.  

Mads at Buchardt answers emails very quickly if you have any problems.  I bought mine just before they were swamped with orders.  I ordered the smoked oak, but took the option of dark oaks temporarily.  So I’ve had the dark oak since April with a promise of late July delivery for the smoked oak.  They really care about the customer and have great comm.  Mads has upgraded me to the spokes oaks as well.  I really appreciate their concern.

I’ve been enjoying these speakers since April.  Just sent and email yesterday and Mads promptly returned an email update.

They are still behind a bit on sourcing the smoked oak and hiring more people.  Apparently they have updated the speakers with some tweaks as well and he believes they have improved the speakers... so I can’t complain as they will send the updated speakers and have been able to listen to these long term... they are keepers IMHO.
They had them at Xponia but honestly they did not sound as good as they are with that setup in the room.

Personally think they did a disservice to the speaker.

I WOULD SEND AN EMAIL TO BUCHARDT AUDIO and ask them, their customer service is extremely good .....my bet is they would be able to give you useful advice.

i am planning on buying a different amp as the Anthem is for my Home theatre and plan sending an email to get advice from Mads Buchardt when I take that next step.

The Dynaudio Excite X18 are 4 ohm and sound pretty good.  They have been discontinued, so you can find them around half price now at about $1000 a pair.

mplstereo

I would worry too much as the Pass 30.8 gives more that you think, and it actually increases it wattage for each halving of impedance as well, so can do half decent current into low impedances.
This is the 30.5 which I take is similar just earlier version.
https://forum.audiogon.com/discussions/comparing-the-pass-labs-xa30-5-to-the-xa-30-8

While the XA30.5 may give 30Wpc into 8 ohms in class-A the distortion at this power level is low, at 0.015%.
The amplifier doesn’t actually clip (defined as the THD reaching 1%) until a much higher power level:
130Wpc into 8 ohms
195Wpc into 4 ohms
332W into 2 ohms single channel driven

Cheers George

There is a better than average chance that the 30.8 and a vast majority of amplifiers both S.S. and tube will perform better with a higher impedance speaker. The impedance swing will be a less significant factor with S.S. than tube however. I think that you shouldnt worry about the impedance and concentrate on buying a speaker whose sound you like. 

I looked at that Buchardt site and those S400 speakers look amazing. If I were doing this, I would try out the speakers and stands, you really have nothing to lose. I bet it will sound really right with 30wpc of pure Class A power. If you live in the US, I bet it would probably be under 3K. Don’t cheap out on the speakers, especially with an expensive amp like that. If you cheap out, you will become dissatisfied wityh the speakers really quick. I’ve been there and done that a few times over the years myself. It ends up costing you much more in the long run.

Synergy, ok.  I will have to focus on that when eyeing speakers.  Given the cost of the amp, used, it will be a bit after I purchase it before I get speakers, so I hadn't totally thought that far, other than at least validating most book shelf's will work ok.   Tentatively, I wasn't planning on anything over $2k/pair, not that I need to or am aiming to go that high. I will have to find a Pass dealer, probably just buy the speakers there, and I really want/hope I can listen to some speakers with the 30.8.  

I've never owned a Pass amp but have a couple of friends that have owned many of their models and they both think that the 30.5 and 30.8 are the best all around sounding amps in the line if their power works for you.  One of the reasons I recommended the Buchardt is that you can listen in your home for 30 days and they pay the shipping both ways and refund your money if you don't care for them or they don't work for you.  I am keeping mine.  Another model to look at is the Reynaud Bliss Jubilee and you can call Bob Neill at Amherst Audio and talk to him about it as he has personally owned Harbeth's, Spendors and Audio Note's in addition to the Reynaud's. Both speakers will work well with the Pass and are extremely musical. 

Synergy between amp and speakers is paramount. If possible, audition your amp with prospective speakers. Some combinations work well together and others not so well.
You didn't mention your price limit? In my system I use a NAD integrated with a pair of PSB Imagine B's ($1000/pr). Synergy is very good with NAD and PSB. Do some research and you may find a good match with your amp.

Jackd,
    Found a hometheaterhifi review that compared the 30.8 and the x150.8, and it really secured my interest in the xa30.8 over the x150.8.  Also I did follow up with reviews comparing 30.5 to the 30.8.  This also explained the class A and AB for both and bumps with what your saying.  This has been very helpful.  My listening levels are low.  I enjoy long hours of listening after work, while relaxing, and reading online.  Rocking out for me would be volume loud enough just to the point where I wouldn't hear a person speaking from 5 feet away or so, rarely.  I was able to get enough volume out of my Bose mini when I had that, those little rechargeable ones.  :)  

    Plowed through reviews, did see a lot of identical speakers among listeners, most were panel or floor, and few bookshelf (which partly worried me) but now that I have learned I have more freedom then I thought I did with bookshelf's, I'm not as concerned.    Maybe most folks that have these amps have more room in their home for larger setups so bookshelf's just are not as popular for that reason?  No matter.  

   Thank you for helping clarify this stuff.  Now I feel like this amp is way to good for me!  Kidding.  

I have TAD ME-1 and technically they are bookshelf size although I think they come with the stands. The sound is incredible.

@mplstereo: i have the xa30.8 and it sounds good driving 8 ohm loads. However, when driving difficult 4 ohm loads it becomes a whole new amplifier. I much prefer 4 ohm speakers with mine. I have had amazing success with the elac uni fi or adante range. For the money those uni fi speakers amd this amp are amazing.  

It stays in class A at it's published rating.  Somewhere above those ratings it goes into A/B and continues to 130 and 195 wpc at 1% distortion.  Best thing you can do short of actually testing the amp with speakers is to read all the reviews of the 30.5 and 30.8 and see what speakers that used with them.  Unless your listening room is cavernous and you intend on playing to concert levels then the 30.8 will push most any bookshelf speaker you find to "reasonable" levels.  

Thanks everyone!  

Wow, this amp was underrated that much?  

Yogiboy - I read in forums from individuals (who may have been uneducated or misinformed) that to get some volume/power get a 4 ohm speaker, that this would bring the output to 60w/ch.  To be honest, researching this amp has been really confusing. I don't know much about ohm's at all.  And now I'm understanding that the amp really makes 100w/ch at 8 ohms fully class A.  SMH, guys like me can't read between the lines with this high tech stuff!

Jackd - Yes, I read that too!  But I just didn't understand it.  I mean, the underrating is so much, that i almost didn't consider it because I was feeling it wouldn't work well with many speakers.   Their power specs are frustratingly misleading and seems weird.  So it stays class A all the way to 100w/ch?  That's plenty for me, but what gives?  Why such the variance?  

So I think the question I need to be asking, just so I am clear, is: are there types of speakers I need to avoid?  (This whole underrated concept and 4 ohm preference talk is making this confusing!  ha)

Also, to be clear, in 4/8 ohm, it stays class A  to 100w/ch?

What about efficiency?  I read that it prefers speakers above 85 for sensitivity?  

It sounds like I should have no issue driving any book shelf speaker, at all, or floor for that matter.  

Any catches, things I might not be seeing?  

Thanks again everyone!

The Aerial 5t is a 4 ohm speaker. BTW, why do you feel that you need a 4 ohm speaker? The impedance changes with most speakers!
https://aerialacoustics.com/5t/

REGA RX1 are 6 ohm bookshelf models

http://www.rega.co.uk/rx1-loudspeakers.html

Stereophile measured the 30,5 at 130 at 8 ohms and 195 wpc at 4 ohms and the .8 should be the same or similar so no lack of power reserves. The listed specs are for Class A only at .01 THD

Agree with jackd, also it sounds fabulous with the SHL5+

Buchardt S-400 and you can try it for 30 days and they pay the shipping both ways. Surprisingly good speakers for the money  Also that Pass amp is a lot more powerful than it's spec's suggest. In reality it will put out well over 100 wpc.

https://www.buchardtaudio.com/shop/s400-black