JBL 308P + (JBL?) sub

[Yorkshire Mouth]

I’m thinking of getting a pair of JBL 308Ps. Amir’s review here:

JBL 308P MKII Studio Monitor Review

This is a review and detailed measurements of the JBL 308P MKII 8-inch Monitor (powered speaker). I purchased this from a member a few months ago. New, they cost US $249. The 3 series look the same for good or bad: The large plastic waveguide is really in your face. Wish JBL would provide...

www.audiosciencereview.com

Bass goes down flat to c.45hz before rolling off. Some distortion the louder you go, the lower you go.

I have a sub, a BK XLS200 MkII:

XLS200-DF

The more knowledgeable and able may wish to look elsewhere for accurate, independent figures, but I’ve found this:

BK XLS200 SPL Measurements, good or bad?

Hi, after much time and anticipation my new sub has arrived to complete my setup :grin: so I thought it best to get down to work with the SPL and work out what is going on. I've done an initial pass at this with the sub in its natural position (given what else in the room), this is about 2 ft...

www.avforums.com

It appears to roll of at…erm…45hz. Do I have that right? If so, is there any point even attaching it?

JBL do their own sub, the 310S.

Can anyone - you know, the wonderful members of these forums who, unlike me, know what they’re talking about, know how to read the figures, etc. - please compare and contrast.

I’ve dug out the manual for the 300 series:

https://jblpro.com/en/site_elements/3-series-owner-s-manual

Page 19, the 308s go down to 24hz whilst the sub only goes down to 27hz. So what’s the point? That’s not a rhetorical question.

Over to you. Many thanks.

 

[Music707]

Seems that you misread the specs in the JBL manual. Just give it a second look.

 

[Yorkshire Mouth]

Seems that you misread the specs in the JBL manual. Just give it a second look.

Ah, yes. Many thanks.

It still sort raises an issue of spending £400 on a pair of speakers, then almost £400 more to buy a sub for what? Just 10hz lower? Don’t get me wrong, any improvement is an improvement, but that’s pretty much doubling the price for just a bit more, and even then not going all the way down to 20hz.

Would anyone care to comment on this, because I’m just guessing. The sub wouldn’t just handle frequencies below the 308Ps. The manual suggests setting the crossover at 80hz. My guess is that the sub takes the strain of the lower frequencies - even those the monitors would usually handle - and thus would mean lower distortion (and higher possible volume) from the monitors. Is my guess right?

 

[bodhi]

Ah, yes. Many thanks.

It still sort raises an issue of spending £400 on a pair of speakers, then almost £400 more to buy a sub for what? Just 10hz lower? Don’t get me wrong, any improvement is an improvement, but that’s pretty much doubling the price for just a bit more, and even then not going all the way down to 20hz.

Would anyone care to comment on this, because I’m just guessing. The sub wouldn’t just handle frequencies below the 308Ps. The manual suggests setting the crossover at 80hz. My guess is that the sub takes the strain of the lower frequencies - even those the monitors would usually handle - and thus would mean lower distortion (and higher possible volume) from the monitors. Is my guess right?

It's an old, small and cheapish sub. Usually if you want extension and SPL you go at least with something like SVS SB-1000 Pro for a bit more money.

Then there is that generally music really doesn't have that much going in the lower frequencies. What do you expect to hear when adding the sub? I have only a bit beefier monitors (Genelec 8350) and usually the sub does almost nothing with music.

I won't say this is the case but I have noticed that some people who have uncorrected subs in their living rooms think that the booming bass is what should be there when really they just have 10+dB peaks from midbass down. If you like it just dial the sub up. If you are trying to get neutral response just accept that the JBLs are almost there already by themselves.

 

[Yorkshire Mouth]

It's an old, small and cheapish sub. Usually if you want extension and SPL you go at least with something like SVS SB-1000 Pro for a bit more money.

Then there is that generally music really doesn't have that much going in the lower frequencies. What do you expect to hear when adding the sub? I have only a bit beefier monitors (Genelec 8350) and usually the sub does almost nothing with music.

I won't say this is the case but I have noticed that some people who have uncorrected subs in their living rooms think that the booming bass is what should be there when really they just have 10+dB peaks from midbass down. If you like it just dial the sub up. If you are trying to get neutral response just accept that the JBLs are almost there already by themselves.

I completely get what you’re saying.

Any comments regarding the sub reducing distortion in the monitors by removing lower frequencies?

 

[bodhi]

I completely get what you’re saying.

Any comments regarding the sub reducing distortion in the monitors by removing lower frequencies?

It should, but I haven't noticed anything while testing crossovers from 50Hz to 100Hz.

I might notice if I got hearing protection and really started blasting, but I'm not that interested.

 

[Yorkshire Mouth]

It still raises the question - what exactly is this sub for, if it’s not going to add very much?

JBL are a company who appear to be serious, and who know what they’re doing.

 

[LearningToSmile]

I got the 308P with a sub, but I decided against getting the 310S. It's just not powerful enough. Your BK sub will almost certainly extend lower. From those measurements it looks like it's pretty reasonable to 25Hz if you smooth it out a bit with EQ. Keep in mind that depending on your room you will need to get a measurement mic to EQ everything properly - otherwise integrating a sub is going to be a nightmare.
For distortion, did I think my 308Ps sounded clearer when I crossed them over to a sub at 80Hz? Absolutely. Did I objectively measure it in any way? Not at all

My advice is to start with the pair of 308Ps and a measurement mic, pair it with your current sub, see how room gain you're getting, and only then decide if you need to buy another sub. Keep in mind that any real subs worth buying will be probably even more expensive than the 310S(I echo the recommendation for SVS, in Europe they're still the most obvious choice). But your BK sub should be plenty for 30-40Hz where the 308P is falling off but there's still a lot of musical content(at least in the music I listen to).

 

[Ellebob]

Adding a sub does reduce distortion for the speakers and you will have cleaner sound at louder volumes. You can gain a couple db more volume but usually speakers will play to a certain volume but near their max volume distortion is greater often in lower frequencies so you reduce that distortion.

How do you plan to connect these speakers and sub? Depending on what equipment you are using the BK sub might not have the connections needed.

If the BK isn't ideal for your situation then I would get the JBL sub. Often with studio monitors and their corresponding sub they use a custom crossover to integrate better. So it is not always about the specs and which can go lower/louder, etc. I do like that the SVS has parametric EQ so I am not against the SVS at all, especially if you are using a processor that is handling the crossover duties and not the sub.

 

[Music707]

Ah, yes. Many thanks.

It still sort raises an issue of spending £400 on a pair of speakers, then almost £400 more to buy a sub for what? Just 10hz lower? Don’t get me wrong, any improvement is an improvement, but that’s pretty much doubling the price for just a bit more, and even then not going all the way down to 20hz.

Would anyone care to comment on this, because I’m just guessing. The sub wouldn’t just handle frequencies below the 308Ps. The manual suggests setting the crossover at 80hz. My guess is that the sub takes the strain of the lower frequencies - even those the monitors would usually handle - and thus would mean lower distortion (and higher possible volume) from the monitors. Is my guess right?

In general, it is true that monitors or bookshelf speakers benefit from subs in terms of distortion. In Amir's measurements the JPL 308p Mk II show a rise in distortion below 60 Hz at 86db. The sub that you have seems to go down to 22 Hz so that perhaps you need not pay for a better sub but can just use what you have. (Edit: Reading your post below it seems that the BK contrary to the 310 does not offer help for integrating the sub with the mains so that you might require a crossover. Unfortunately, I cannot share any experience in that regard.)

What all those general considerations cannot take into account is the room gain in your room and your required SPL as a result of your listening distance and your listening volume.

I you want more precision, taking measurements might be the next step.

 

[Yorkshire Mouth]

Adding a sub does reduce distortion for the speakers and you will have cleaner sound at louder volumes. You can gain a couple db more volume but usually speakers will play to a certain volume but near their max volume distortion is greater often in lower frequencies so you reduce that distortion.

How do you plan to connect these speakers and sub? Depending on what equipment you are using the BK sub might not have the connections needed.

If the BK isn't ideal for your situation then I would get the JBL sub. Often with studio monitors and their corresponding sub they use a custom crossover to integrate better. So it is not always about the specs and which can go lower/louder, etc. I do like that the SVS has parametric EQ so I am not against the SVS at all, especially if you are using a processor that is handling the crossover duties and not the sub.

The system will be fed by XLR balanced outs from my Topping EX5. If I use the BK, then the Topping also has RCA outs, and both these and XLRs can be used together. As a result, full frequency will still be sent to the monitors, negating any distortion advantages.

If I get the JBL sub, it’s XLRs from Topping to sub, crossover set to 80hz on the sub (recommended by JBL for when using with the 308s), then XLRs to the 308s.

 

[Ellebob]

I would get a new sub. There is really no benefit to using your sub with that DAC except for filling in the very low end. You would have to set your sub's crossover pretty low to match the low frequency cutoff of the 308s. This would not give the lower distortion nor does it allow you to place the sub in best location for best bass response.

 

[gino1961]

Hi interesting topic indeed
I am intrigued by the 2+1 solution even if two subs one per channel would be easier
I love the sub plus satellite solution a lot Decoupling the sat from the sub could prevent the low vibes to reach the sat
Moreover if you cut out the lower frequencies from the sat the IMD of the sat will decrease resulting in a cleaner midrange and High range
The big issue is the optimum cross frequency between sub and sat
From 80 to 200 there are many options viable
If it's low you need a bigger woofer in the sat
If it's higher smaller SATs could be just fine
I am still very very confused

 

[Ellebob]

The crossover should be set by where you get the best result. In most rooms that is between 80-100hz. If using the JBL sub and you are using the sub for the crossover by connecting your left and right channels to it and then connecting your speakers to the sub, use the sub's 80hz setting.
If connecting the sub to a processor start at 80hz. If you the capability to measure the response the check it and then try 90hz and 100hz (or5hz increments) and see which works best.

 

[gino1961]

Hi thank you very much for your very useful advice
I would not used small monitors in full range expecially with high SPLs in big rooms The IMD would be very high They have physical limitations
a 8 inch woofer should be cut at 100 Hz or even higher to get a clean response during music peaks
it is quite logical When the woofer is asked to produce a strong 80 Hz and a 2 kHz signal in the middle you will see IMD products
i prefer 12 inch subs The bigger woofer moves less and so will have less distortion at same Hz and dB
It can cover the range below 200 Hz very well (i.e. with low distortion)
i prefer the more expensive 2+2 solution An expert from JLAudio convinced me
Maybe he just wanted to sell more subs

 

[ZolaIII]

I completely get what you’re saying.

Any comments regarding the sub reducing distortion in the monitors by removing lower frequencies?

Take a look at Dynaudio BM9S II sub if you need balanced I/O and high pass trough it with 60 and 80 Hz switch. It's a bit pricey but I don't know better with balanced line (especially pass trough with high pass). There is & 2x 10“ model but considering price you should pass. I wouldn't go with down firring or ported and future more would plug the main ports.

 

[Ellebob]

Using more than one subwoofer depends on youjr situation. The long sound waves that bass creates aynwhere from 14 feet to 56 feet from 80hz down to 20hz respectively, behave differently than mid and highs in the way they interact in the room. You can have very different bass response depending where you are listeing in the room. To correct this and many of the room mode problems in smaller home sized rooms, multiple subwoofers are used. This will get a more consistent response for most of the seats in the room. What is the purpose of your room? How many listeners? How important is it that all the listeners have a similar experience? Sometimes you hjave to accept that there will be some cheap seats that don't perform as well.

If you only care about one listener, then one sub will work great. Find a good spot for the listener and the sub and you will also need a little EQ.

If you have myltiple listeners and they are all away from walls and corners then you can get a very good response with 2 subwoofers. Howeverm they need to be well placed to correct some of these bass problems. EQ will also be needed. A lot of reading to do on this. I don't have the time to give all the various locations that typically work well and it will vary depending on your room. Harman has SOME examples in their white papers.

Audio Innovations | HARMAN

HARMAN and its powerful, proven and progressive technology are at the center of a connected and ever-changing world.

www.harman.com