Advantages & Disadvantages Of 6.5 inch v 8 inch speakers

[eldarvanyar]

What’s the views and experience of using a 6.5 inch speaker v 8 inch speaker for the bass midrange in a 2 way speaker box

Thanks

 

[Dagis]

I am currently using Fluid Audio FX8 active studio monitors for hifi,
and are having a great time at that.
These are 8" coaxial speakers with class A/B amps and slot ports in the front.

The thing to consider is that studio monitors will be studio monitors,
they are by design very transparent and revealing speakers
and any upstream components that are originally intended to be used
with muffled and rolled-off speakers might come off as nails on a chalk-board when hooked up to stud.mon.

On the other hand there is no passive x-over sucking details and life out of the music,
and I find that to be a great advantage.
Transparency,details,depth,space..I like my monitors very much.

The active JBL line has been getting a lot of great feedback.

My listening space is aprox. the same as yours,
and these coaxial 8" have no problem filling them with distortion free music.
Including tight and quite deep bass.

You might wanna check what type of amplification (A/B,or class D) any given monitor is using,
some people like digital while others prefer A/B.

Positive: one might save A LOT on not having to buy a quality power amp or speaker wires.
Source,preamp and then a couple of RCA`s and active speakers are up and running.

 

[swechsler]

All else being equal, the 8" will go lower than the 6.5" because it's capable of moving more air, and in most cases, both will go up high enough in the frequency range to be able to cross over cleanly to the tweeter. However, it's not usually that simple, and all else is rarely equal. A better designed 6.5" with longer excursion could outperform a mediocre 8". IOW, I wouldn't make the decision based on driver size, but instead, the overall design of the speaker.

 

[fill35u]

You can mount the tweeter slightly closer to the acoustic center of a 6.5" than to an 8", but the importance of this depends on the tweeter, mounting, crossover, and listening position.

All else equal, the 8" will have a slight advantage in sensitivity, low frequency extension, and power handling. But it will start beaming and also break up at a slightly lower frequency.

The difference between 6.5" and 8" is so slight that I can't imagine anybody making a purchase decision based on it. A 2-way intended for high fidelity needs support from a subwoofer, which in turn means the 2-way needs response at intended volume down to at least 60Hz for integration. With such small radiating surface to choose from (between 6.5" and 8"), you'll probably be doing a 2.5-way design with an extra driver or two helping out on the bottom end. And the bottom end is where you'll be very grateful for the slight advantages of the 8".

But very nearfield, and with support from a nearfield sub, a single 6.5" might make more sense.

 

[tomlinmgt]

Mid and upper bass performance is where I think the difference between the two may become apparent...that’s all other variables held constant except the dia. of the cone and cabinet tuned to optimize the driver’s LF performance. That’s purely speculation on my part as I’ve never had an opportunity to conduct an experiment between two speakers that are identical except for the size of mid bass driver. But I wonder...does the fact that there are scads of bass cabinets (as in an actual speaker cabinet for a bass guitar) that use 8” drivers and virtually none that use 6.5” drivers of any relevance here? I think it is.

 

[Lavane]

Some 6.5" drivers can get pretty low with passive radiators.

 

[AstroZon]

On 2-way speakers, crossover points are usually lower on 6.5" woofers and higher on 8" (typically around 2.5k for 6.5" and 4k for 8".) This means that the 6.5" puts more sound through the tweeter than the 8" does. So the tweeter has to have a wider range than on an 8". Normally this has been factored on factory speakers, but for home builds, including repurposed boxes, you really have to look closely at the tweeter compatibility - especially on 6.5" designs.

 

[AstroZon]

Last weekend, I was experimenting with 2 pairs of Infinity speakers, both 2-way, one 6.5" (RS-9) and one 8" (RS-3001.) I wired the RS-9's Polycell tweeter to the RS-3001's woofer and crossover. I thought it would sound better, but the big magnet on the Polycell was too much for RS-3001's crossover. It sucked the sound right out of the woofer. So naturally I rewired the same woofer/tweeter combination using the RS-9's crossovers. It sounded better and cleaner, but now the woofers lacked punch. Morel: there's more to speaker design than specs. Good ears and lot of trial and error go a long way.

Edit: Actually when I ran both sets together they really sounded great. However, since they're both 6 ohm speakers, running both together would be hard on most amps.

 

[AstroZon]

BTW, of all the 6.5" 2-way speakers that I've owned (and I've had plenty) my favorite is my NHT Model 1.3 (actually a 6" woofer.) NHT absolutely got the woofer right on this.

 

[Pio1980]

I built some e-waves based on the Advent 2 with the smaller woofers, dunno size exactly but smaller than 8 inch, and the driver midrange integration vs midbass and upper bottom end with the 6x6 JBL wg horn/Selenium 220 is superb. Surprising bottom end response, almost full-range shallow smallish true bookshelf dimensions.

 

[motorstereo]

Some 6.5" drivers can get pretty low with passive radiators.

Yes they sure can. Polk figured this out in the 80's in several variations and there's still lots of them around making great music

 

[mitchalee]

Just to throw in a wild card, I have some Quads with 4 inch drivers. They are more precise in the mids and upper bass than any 6.5 or 8 I have ever heard. And can get down to a solid 65 Hz near field. Now they will never get as loud without blowing up, but there are always trade-offs. Also, one always has the choice of using 4 6.5 drivers in series parallel. If one is using them in a 3 way system, then they are essentally non-directional and do not even need to be mounted outside or in the front if one is a passable carpenter.

 

[mitchalee]

My Polk Monitor 7 speaker have great bass with 6.5 woofers and 10" passive radiators.

 

[Tom Brennan]

Some 6.5" drivers can get pretty low with passive radiators.

Indeed, small drivers can go as low as large ones if you're willing to give up efficiency and output.

 

[Pio1980]

AR used 8" in their two-way designs, notably the very popular 4 series and it's equally successful derivitives.

 

[MuseChaser]

Some 6.5" drivers can get pretty low with passive radiators.

...or transmission line enclosures...

Another possible benefit of using the smaller 6.5" driver is the potential for a slightly smaller/narrower baffle, which may place the diffraction step in a more desirable place dependent upon driver characteristics and crossover design, and may benefit imaging and more uniform dispersion characteristics.

 

[Lavane]

...or transmission line enclosures...

Another possible benefit of using the smaller 6.5" driver is the potential for a slightly smaller/narrower baffle, which may place the diffraction step in a more desirable place dependent upon driver characteristics and crossover design, and may benefit imaging and more uniform dispersion characteristics.

Polk made a few speakers with two or more 6" midbass drivers with one driver being tuned differently from the other. I keep looking for a pair of the Monitor 11's that did this. I have a pair of Monitor 10's I like. A soft dome tweeter, two midbass drivers and a passive radiator. They dip into the high 20hz range.
They can really belt out some volume with a 275wpc amp I have.

 

[Fomoco1649]

All else being equal, the 8" will go lower than the 6.5" because it's capable of moving more air, and in most cases, both will go up high enough in the frequency range to be able to cross over cleanly to the tweeter. However, it's not usually that simple, and all else is rarely equal. A better designed 6.5" with longer excursion could outperform a mediocre 8". IOW, I wouldn't make the decision based on driver size, but instead, the overall design of the speaker.

Sounds like the truth to me....

 

[flavio81]

What’s the views and experience of using a 6.5 inch speaker v 8 inch speaker for the bass midrange in a 2 way speaker box

Thanks

2-way speakers have been made with 6.5, 8", 10", and even 12"

Obviously a bigger driver moves more air thus less displacement thus not just better bass response but potentially less distortion, all else being equal.

The bigger the driver, the lower the frequency where beaming starts to be a problem, so it needs to be compensated for in one form or another. The side effect of this beaming is very narrow directivity at the XO frequency, which might or might not be a problem for you.

So to compensate this requires one or more of the following...
(a) lowering the XO frequency. The lowest XO frequency i have seen for a non-horn-powered 2-way was about 1 or 1.5KHz.
(a.1) ...thus, a tough tweeter capable of increased power handling
(b) using a more elaborate crossover, like a 24dB/oct crossover
(b.1) ... or going fully active
(c) some esoteric magic involving the dust cap and cone corrugations to reduce beaming

My desktop speakers are JBL 4408 which are 2-ways with 8" woofers, crossover frequency 2.5Khz. These are mighty fine to me, but then they are used near-field.

My living room speakers are currently NS-500, which are also 2-ways with 10" (ten inch) woofers, crossover frequency 1.8 KHz. The tweeters on this speaker are beefed-up and very special. I love the sound but yes, they do have vertical directivity problems, so the listening height is critical to enjoy them.

Dynaudio makes the BM15 10" 2-way nearfield monitor and it gets glowing reviews.

So, my conclusion... 6.5" inch? lol put some horsepower on your motor... Just joking, 6.5" will enable better directivity and maybe better transient response too. But i can't see how it would give deep, loud bass without being a power hog and without the bass excursions intermodulating with the midrange and robbing detail.

 

[flavio81]

A better designed 6.5" with longer excursion could outperform a mediocre 8". IOW, I wouldn't make the decision based on driver size, but instead, the overall design of the speaker.

However if you want linearlity/lower distortion is better to keep excursion short, enabling an underhung voice coil and enabling the coil to be in the most linear part of the magnetic field.

As far as i know.