to add a subwoofer or not to a full-range stereo speaker system?

[atomant]

the left channel null at 45Hz and the both-channels dip at 250Hz.

Point taken, thanks!

It would be feasible to EQ them but at the expense of a global 6 to 20 dB reduction in SPL across all the bandwidth, i.e. 60-70 dB instead of 75-80 dB SPL for the same volume settings. Already tried that several times. I still have the filter files to retest and compare.

Will need to take a new set of measurements soon as the furnitures in the room have changed a lot since, added 2 doors as well to get the side walls more symetrical and get rid of an alcove on the front area of the room.

Futhermore, I'm changing the actual woofers (RS 40-1301) for a pair of Peerless SLS-315 or Dayton DCS305-8 when I can locate some locally.

 

[Hear Here]

They were installed in an enclosure I built myself based on plans published in a 1973 book by Gilles Poirier. These were enclosures designed for the BBC. The front and rear panels were filled with compacted sand to eliminate vibrations and were nearly 2 inches thick. For this reason, I'm considering keeping them and will consider your suggestion of replacing them with something more compact and modern.

One is always loath to chuck out or sell at a low price a speaker system one has lavished many hours and lots of cash on, albeit 50 years ago!

I was lucky in selling my Airedales for a good price, though I suspect the KEF drivers were the main selling point - and they looked pretty good after I decided against the upward-facing mid and top drivers in the Wharfedale originals and substituted slim walnut strips to replace the Tygan covering that was so popular at the time! Incidentally my speakers were 4.5 cu ft and also featured a sand-filled panel and quarry tiles to add substance to the larger panels. The cabinet was designed for wall or corner placement, so hexagonal in plan. Made construction a bit tricky!

 

[theREALdotnet]

Anyway the only thing the OP needs to 'fix' in his graph from the measured position, is the left channel null at 45Hz and the both-channels dip at 250Hz.

The latter is likely from bass drivers located about 35cm above the floor. This will be difficult to tackle, and may not be worth it. Most speakers have a dip somewhere in that region, depending on where the woofers are. Some speaker designs use additional bass drivers higher up (some even above the tweeter) to compensate for that.

 

[atomant]

bass drivers located about 35cm above the floor

The woofer center is at 1m from the floor precisely; the event, at 24 cms.

 

[theaudiopath]

I have an alternative suggestion. As the errant speakers you are wishing to replace are 15's Why not replace with the same size? I think despite their apparent issues. Which from your description are likely due to the surrounds hardening up. The sense of acoustic image & scale each 15 creates as they move that mass of air might be sorely missed if you go to something smaller.

SB acoustics make some very credible 15's with very high efficiency in their upper models. There are plenty of others to choose from If I understand correctly you were saying are going to run on only 50 watts which I would suggest doubling. Not for more SPL as you don't seem to need it. But for more clean headroom. For transient attack. Ie the thwack of a snare drum that makes you jump out your seat, the punch in the chest & guts @ the thud of a kick drum & all that good stuff that makes the low end inject LEBEN or life into canned music. And only a BIG high efficiency driver will do that for you. With that barely adequate wattage currently powering your low end.

I think you don't NEED a sub. But if you DO go there why hold back? Go for some Rythmik [That's how is actually spelled] audio servo controlled 15's A much improved modern version of the Philips motional feedback system they developed for their active speakers. To better control & limit bass over excursion that's still an issue to this day, as it was back in the 70"s Along with their Rythmik plate amps. Yes they are subs but really REALLY good ones. Super tight and super fast with transient attck that can stop on a dime! A universe away from the slow & heavy fart boxes most people THINK is good low end. If I had the money That's what I would buy for myself. And I'm a VERY fussy bastard when it comes to audio! I believe you can run them up to a 300Hz XO point to the mids & tweeters. Anyway thats my 2 cents worth.
Cheers from down under. Australia that is.

 

[Hear Here]

I have an alternative suggestion. As the errant speakers you are wishing to replace are 15's Why not replace with the same size? I think despite their apparent issues. Which from your description are likely due to the surrounds hardening up. The sense of acoustic image & scale each 15 creates as they move that mass of air might be sorely missed if you go to something smaller.

Certainly the least costly solution (no need for major cabinet surgery) is to replace the old 15" driver with a new - and better – 15” one. However we don't know the crossover frequency being used. Often speakers of that vintage used 300 Hz or so. All 15" drivers will struggle with the upper reaches of that range (for the reasons described in my earlier post) so perhaps the OP could adjust his active XO to ensure the 15" driver handles only sub 150 Hz or so. This may mean the mid driver needs to be checked for its ability to handle lower frequencies than it’s used to!

In view of the size of the enclosure, it may be possible to cut out a section of the front baffle, insert a fresh panel to mount twin 12" or even twin 10" modern drivers for improved bass

 

[atomant]

I have an alternative suggestion.

I totally agree to what you said.

First, some precisions on my material:
My original speakers were 100W, or maybe 50W only, that is unclear as they are 50 years old.
My bass power amp is 150W; my midrange (Quad 303) is 45W; and my high (custom design) is 25W.
XO freqs are ~ 333 and 3333 Hz

I'm trying to locate some Dayton Audio DCS380-8 which are 15", 8 ohms, should such a model even exists, and so far only found the 4 ohms model DCS385-4 readily available in pair. They are rated 300 W.
1) My bass power amp is rated 8-16 ohms.
2) They are twice as pricey as the 12" DCS305-8. Out of my budget.
3) They're probably oversized for a 9 cu in enclosure and I might have to tune down the vent freq.
4) I wrote to solen.ca for availability of both the 12" and the 15" in 8 ohms. This could be problematic. All Peerless speakers, my first choice, are out of stock.

I had a look at the SB Acoustics

SB34NRXL75-8​

but they are 4x the price I'm expecting.

What do you think of the GRS

RSRMO-8​

?
The GRS RSRMO-8, 387mm (15in) is a Replacement Woofer for 15" Realistic Mach One 8 Ohm.

===========

Update:

Allright, located some Dayton Audio DCS380-8 and ordered a pair already

 

[atomant]

Certainly the least costly solution (no need for major cabinet surgery) is to replace the old 15" driver with a new - and better – 15” one.

They are twice as pricey as the 12" I have an eye on, minimum

However we don't know the crossover frequency being used. Often speakers of that vintage used 300 Hz or so. All 15" drivers will struggle with the upper reaches of that range (for the reasons described in my earlier post) so perhaps the OP could adjust his active XO to ensure the 15" driver handles only sub 150 Hz or so. This may mean the mid driver needs to be checked for its ability to handle lower frequencies than it’s used to!

333 and 3333 Hz. Mid is 6" speaker 85W from Maddison

In view of the size of the enclosure, it may be possible to cut out a section of the front baffle, insert a fresh panel to mount twin 12" or even twin 10" modern drivers for improved bass

Originally, I had no money for the 15", I was a student and was always broke so for the first years, the woofers were 12" instrument speakers from Radio Shack mounted on a circular adapter for the 15" design. So, it's not a problem.

 

[levimax]

I have an alternative suggestion. As the errant speakers you are wishing to replace are 15's Why not replace with the same size? I think despite their apparent issues. Which from your description are likely due to the surrounds hardening up. The sense of acoustic image & scale each 15 creates as they move that mass of air might be sorely missed if you go to something smaller.

SB acoustics make some very credible 15's with very high efficiency in their upper models. There are plenty of others to choose from If I understand correctly you were saying are going to run on only 50 watts which I would suggest doubling. Not for more SPL as you don't seem to need it. But for more clean headroom. For transient attack. Ie the thwack of a snare drum that makes you jump out your seat, the punch in the chest & guts @ the thud of a kick drum & all that good stuff that makes the low end inject LEBEN or life into canned music. And only a BIG high efficiency driver will do that for you. With that barely adequate wattage currently powering your low end.

I think you don't NEED a sub. But if you DO go there why hold back? Go for some Rythmik [That's how is actually spelled] audio servo controlled 15's A much improved modern version of the Philips motional feedback system they developed for their active speakers. To better control & limit bass over excursion that's still an issue to this day, as it was back in the 70"s Along with their Rythmik plate amps. Yes they are subs but really REALLY good ones. Super tight and super fast with transient attck that can stop on a dime! A universe away from the slow & heavy fart boxes most people THINK is good low end. If I had the money That's what I would buy for myself. And I'm a VERY fussy bastard when it comes to audio! I believe you can run them up to a 300Hz XO point to the mids & tweeters. Anyway thats my 2 cents worth.
Cheers from down under. Australia that is.

^This!^ A modern 15" driver (there are a lot of free speaker CAD tools to help you select the best one for your enclosure) will give you better performance in every way and make a sub unnecessary. The more I learn about proper sub integration the more I try to avoid them... time domain is important for quality bass and the more subs you add the harder that is to achieve. Multiple subs will get you a "smoother" FR but that does not guarantee "preferred sound quality". You might also want to look at a bigger amp for the woofer as well, modern 15" drivers can handle a huge amount of power. Don't overlook some of the 15" "Pro" woofer drivers like Lavoce or Eminence. They are most likely better suited to your needs than a "modern heavyweight" 15" Hi-Fi subwoofer driver. Have fun!

 

[atomant]

The adventure has started.
Ordered a pair of Dayton Audio DCS380-8 for the same price as the most recommended powered subwoofer on Amazon I was considering installing.
Thanks for the advices!

 

[theaudiopath]

I have an altrnative suggestion. As the errant speakers you are wishing to replace are 15's Why not replace with the same size? I think despite their apparent issues. Which from your description are likeley due to the surrounds hardening up. The sense of acoustic image & scale each 15 creates as they move that mass of air might be sorely missed if you go to something smaller. SB acoustics make some very credible 15's with very high efficiency. If I understand correctly you were saying this 15 is run w 50 w?
A bit more headroom would be something you would definitely hear as an improvement subjectively. so a 100w + or double that.
Would give those 180 g cones a little more control. Class D sucks for antything but bass IMHO. But in this application they absolutely ROCK. Inexpensive powerful and in CONTROL

 

[theaudiopath]

Good choice atomat. But @ 91 dB. I seriously think a few more watts driving that sucker would be a really good idea.
Just sayin! It's all you @ your call. Just trying to give you a better musical experience. That's all

 

[atomant]

a few more watts

Thanks, it's a 150W already. Only for the bass channels 7-333 Hz.

 

[theaudiopath]

Cheers. My bad, didn't catch that part of the equasion. Should hopefully sound much better once installed & tweaked.

 

[krabapple]

I think you don't NEED a sub. But if you DO go there why hold back? Go for some Rythmik [That's how is actually spelled] audio servo controlled 15's A much improved modern version of the Philips motional feedback system they developed for their active speakers. To better control & limit bass over excursion that's still an issue to this day, as it was back in the 70"s Along with their Rythmik plate amps. Yes they are subs but really REALLY good ones. Super tight and super fast with transient attck that can stop on a dime! A universe away from the slow & heavy fart boxes most people THINK is good low end. If I had the money That's what I would buy for myself. And I'm a VERY fussy bastard when it comes to audio! I believe you can run them up to a 300Hz XO point to the mids & tweeters. Anyway thats my 2 cents worth.

are we back to 'fast ' and 'slow' subwoofers

so much....lore

OP's in-room response looked pretty darn good except for two nulls. Instead of focusing on that, this thread has gone off into the wilderness. Happy trails, guys.

 

[atomant]

Oops, while I was retuning the ports for 20 Hz, I noticed the speakers were the 1980 model 40-1308 rated at 75W, not the older 40-1301. They are still in surprisingly good condition though!

 

[atomant]

are we back to 'fast ' and 'slow' subwoofers

so much....lore

OP's in-room response looked pretty darn good except for two nulls. Instead of focusing on that, this thread has gone off into the wilderness. Happy trails, guys.

No worries, I'm use to it in forums. That is the rule, not the exception.

I will be back on topic once the new woofers are installed, tuned, new REW measurements being made and correction applied Might take a few weeks.

Thanks for your interest!

 

[krabapple]

Heard it, KNOW it. The end BYE NOW!.

Lemme fix this for ya to make it apropos Audio Science Review:

"Heard something, THINK I know what caused it. But could be WRONG!"

Cheers!

 

[krabapple]

That's a lotta words in the service of missing the point.

 

[atomant]

First impressions.

They weigh a lot more, the magnet is larger, so is the spider.
I've replaced 1 of 2 to do some A/B testing. It's not very conclusive because lack of directivity at those frequencies. There are subtle differences though with the sound I use to hear with my test audio files.
Comparing DaytonAudio DC380-8 (left) with Realistic 40-1008 (right).