Integrating a Subwoofer to my Stereo setup

[john_k_antony]

Hi all,

I have been "idling" for a while due to some personal and professional reasons. Now I am back to my passion.

I love to do experiments and wanted to try integrating a Subwoofer to my existing stereo setup. The idea is NOT to increase the quantity of bass, but to get more balanced and quality bass from my system. I said this is an experiment and wanted to try different options.

Now this is my existing setup

1. Source : Oppo 105 / Technics SL Q33 (restored and serviced by Mr Kuruvilla Jacob)
2. Pre : DIY Pass B1 + CNC Phono stage (experimenting here as well with the output resistor mods)
3. Power : Acoustic Portrait NJ1
4. Speakers : KEF iQ7
5. Speaker cables : "TNT" cables (as one FM calls them ) from Mr Murthy.

The above system sounds pretty good for my ears and of course the bass tends to go out of control in some occasions. So I just wanted to try integrating a Subwoofer to balance the bass response.

I am trying to integrate Velodyne EQ Max 10 to the above system.

The Subwoofer has both low level and high level stereo input and output options.

I have thought about 5 theoretical options to set this up.

Option 1 :

Forget about this experiment, keep things simple and do not try to integrate the Subwoofer to the existing setup .

Option 2 : (This is how I just set it now)

Pre -> Sub low level L & R in.
Sub low level L & R out -> Power amp -> Speakers

The crossover filter is set to 50Hz in the Subwoofer.

I do find an overall bass response improvement with the above setup, but have a strange feeling that the crossover in the Subwoofer is "robbing" some music. I need to do some quantitative measurements using REW to see if there are any freq response changes compared to the setup before the Subwoofer integration.


Option 3 :

Pre -> Power amp -> Sub high level / speaker level L & R in -> Speakers

Some Sub manufactures and internet search suggest this method over the usage of low level input and output.

Option 4 :

Use the low level input / output, but do a parallel connection. Use a "Y" connector from pre and route the same signal to Power amp and Sub woofer.

Option 5 :

Use the high level / speaker level input / output, but do a parallel connection. Take two sets of output from Power amp and feed one pair to speakers and other pair to high level input of Subwoofer.

In Option 4 & 5, my main speakers will get full range signal and I will end up with "double bass" that might defeat my whole purpose, which is not to increase bass quantity.

I would love to hear your opinions and experience.

Thanks,
John.

 

[Beast_of_burden]

Option 2 is the worst possible method. The sub's low level output is most likely at a higher impedance which will effect the transfer to the power amp. Option 4 is the best bet which is why I always look for two outputs on the pre. Parallely connecting output from power amp to sub is the next best option. RB81 will compete with the sub no doubt but better than a floor stander. I managed to integrate a RB61 with a ML Dynamo only after adding a room equalizer to the mix and heavily damping the room.

Where did you get the RB81 from? I am looking for a pair.

 

[john_k_antony]

I picked RB 81 from Cinebels, Phoenix Mall, Mahadevpura.

Thanks for giving your thoughts on the Sub integration. As I was saying, I "felt" something is missing with my current setup (Option #2) though there was an improvement in Bass. I will try Option #4 next.

BTW, the Sub integration I am talking about is for my Stereo setup and the speakers are KEF iQ7. RB 81s are used for HT and for HT, I have 2 x Velodyne EQ Max 12 and the entire HT system is "Pre-Proc'ed" and Powered by Emotiva gear. Pretty happy with that setup.

Since my Pre doesn't have two outputs, would I get good results by using basic a "Y" connector and routing the same signals to Sub and Power Amp? Would this result in "double bass" as my main speakers will get full range signals. I know my fronts are rated at 42Hz at low end and I want the sub to cover 28-50Hz range, but still will there be some bass doubling at those frequencies where my fronts are rolling off and the high pass (50Hz) region of sub?

I did read about in other forums where people recommend using high level speaker lines instead of low level. Which is Option #3. Seems like REL recommend high level connections for stereo integration. http://rel.net/support/rel-set-up/

Thanks,
John.

 

[prepress]

^+1. But if you really feel the need of Sub, then you should do some sound level tests between L/R speakers and Sub. Keep that at low level 7-8 o'clock. So that it just add a slight flavor of under 40Hz but not much. This way you may not need to adjust the control for every song. Sub will remain silent for above 40-50Hz frequencies but would sound (at low level) when required.

By the way I am also planning to do it

 

[GeorgeO]

John

A sub definitely adds to the experience-IMHO. I use Option 4 in cases where I dont have a pre. There is some trial and error involved but once it's up and running you will thoroughly enjoy it.

 

[Beast_of_burden]

I have found that it is easier to integrate bookshelf speakers with a sub rather than floorstanders. I have floor standers and it was just way too boomy bcos of the two woofers. I disconnected one of the woofers in each channel and the integration was easier but not straightforward. I still had to use the room equalizer to get it just right. Now it is nearly perfect even at low volumes. I fully agree with George that a sub can make a huge difference. And mine isn't even a very expensive sub, its a wharfedale 10 inch ported sub. The digital room equalizer is doing all the work in this case.

Your best bet is to set the sub cutoff 40 Hz -/+ 5 Hz. 40 Hz is too low a cut off, i prefer 80+ in stereo systems. Start at a low level and increase in really small increments. Pull the sub out to somewhere in between the mains and a bit further out away from the back wall. Pull your mains also away from the back wall. Stuff the ports on the mains. If your sub has an equalizer, attenuate at the cut off frequency to reduce the double bass effect at the cross over point.

Borrow a Deq2496 and see if satisfactory integration is at all feasible. You can also use REW to understand the pro blems.

 

[arj]

John, I would go with option one, no sub at all. I have tried this you know, but I would say integrating a sub to a stereo set up is not a good idea at all. First of all, setting the cross over frequency correctly is one hell of a job, you won't get the integration correct and the bass sound and the other higher frequencies go in different directions. If at all you get the correct setting, it keeps changing with each song and you may have to adjust the sub for each song. Its my humble op.

having run dual RELs for a long time, rather successfully, i would say it is tough to get right but once you do it goes very well.
The big mistake most folks make is keeping the crossover too high and the position of the sub wrong (corssover/phase and position are all connected) and thats why the settings need to change. ideally you need a reference cd to set the level but once set you never need to change it unless you change the speaker/sub position.

 

[john_k_antony]

Thank you all for the great inputs and suggestions.

I totally agree with George Sir, that even without proper setting up and balancing, the Sub really did add some magic into the over all stereo experience. But yes, I do feel that something is missing with the current setup that I have - Option #2.

Now I am going to try the Option #4, before I order another set of speaker cables to try the Option #3 & #5.

This is what is planned

1. Hookup Option #4. That is connect the Sub using a Y connector from the Pre and run it parallel with main power amp.
2. Start with the Sub cross over setting at 40Hz and slowly increase it to the "desired" level.
3. Close the port in my main speakers. I did noticed that closing the port in my KEFs did reduce the bass in the past. Now with the Sub in place, this will be good experiment to try.

I do have an acoustically treated room that helps in the overall sound.

I also have a working REW setup with umik-1. I will run REW after I hook up Option 4.

I also need to do the resistor mod on my Pass B1.

Will update you guys with the results after I try these out.

Thanks,
John.

 

[Hari Iyer]

IMO getting the subwoofer phase correct with the main speaker is going to be the key to get a balanced and well integrated system. Try the below method to get the proper phase angle setup,

1. Place your main left and right speaker at the best possible listening position.
2. Place your subwoofer also in the best possible listening position.
3. Connect your main speakers (left & right) with reverse polarity. Yes - connect it reverse.
4. Play a music with a good decent bass note.
5. Adjust the main speaker and subwoofer volume to a decent level
6. Turn the phase knob of the subwoofer to the position where you get very minimum bass, You can sit at your listening position and ask your attendant to adjust this phase knob.
7. Once you have got the lowest bass at this phase position, go ahead and connect the main speakers with the correct polarity.

This will ensure that your main speakers and subwoofer phase are correct and this will give you a more balanced sound with pin-point integration and imaging.

Let us know after you have done this for benefit of FMs.
Cheers,

 

[john_k_antony]

Thank you for the suggestion Hari. I will try this out and let you know the results. As I said before, this is an experiment and I would be doing it when ever I get some free time.

But before I try this, what would you recommend as the best possible connection option? I know you build speakers and have read most of your comments in the past and they were very informative. So I would kindly request your opinion on the best connection option for me based on your experience.

If you could please look at my first post with different connection options and suggest me the right option, it would be really great. I was planning to try out the Option #4 (parallel low level connections to Sub and Mains).

Thanks,
John.

 

[arj]

I would suggest option 3. And as a starting put the sub at the position you will sit, put the volume of the sub at high and then put your ear level near the floor at the places where the sub can be put. The place you hear it cleanest ( relatively) is the optimal spot.
Now place the sub there and keeping the volume again high change the phase where again the volume is highest at your listening spot.. This is the best phase
Now you need to get the crossover right..so reduce the volume approx to the speaker level and start with 10 db point of gone speaker and keeping increasing the crossover till you get a feeling the speaker and sub has blend in.. This is the most difficult part to get right and may involve even adjusting the position of the sub slightly
Now again adjust the volume so that you just heard the sub

The philosophy of using a sub is that you don't hear it when the sub is on but miss it when it is off..and that's where 90% of people get it wrong.

 

[john_k_antony]

Thanks for the tips arj.

Do you recommend any good tracks that you use as reference for setting up the Sub?

Thanks,
John.

 

[arj]

My favourite has been Eric Clapton Unplugged. most tracks from track 3 have 20-25hz drum which should be heard clearly.

 

[john_k_antony]

My favourite has been Eric Clapton Unplugged. most tracks from track 3 have 20-25hz drum which should be heard clearly.

I assume you are talking about this one

Unplugged (Eric Clapton album) - Wikipedia, the free encyclopedia

 

[arj]

Yes the same

 

[arj]

The first track of the album Reptile by Clapton also is a very good one..it has an overload of bass

 

[Shivam]

I use an AP pre-power setup with dual REL subs. The subs were calibrated using a RTA and pink noise and the integration is such that when the subs are off, I don't miss anything. When they are on, I can feel the low extension in some of the classical music work (especially low contra-bass and organ music). Nothing works better than pink noise with RTA for sub placement and setup.

I listen to most of the bollywood music, ghazals, country music, popular music etc without the subs switched on. I enjoy blues, jazz and western classical with the subs switched on.

Some of the music which is problematic is that with drums in the mid bass region. To get a party feel, the bass needs to be of high energy and tight (think Bob Marley). If I go with the RTA readings, the music sounds robbed of bass compared to what I have heard in most of the good setups in various homes.

 

[john_k_antony]

Thanks for the input Shivam. I did follow your thread earlier regarding your Sub integration to your AP setup. If I remember correctly, you wanted a Sub just to get one song right ?

BTW, did you do RTA with REW or some other setup? I have a working REW setup already in place and have tried the RTA before. The results were not that satisfactory. So I thought of experimenting to fix some of the issues with a Sub integration and may be playing with some phase/location adjustment to nullify couple of unwanted peaks.

It seems like I should get the parallel connection option to integrate the Sub. This will let me switch the Sub off when ever I don't need it and still have the full range signal fed to my mains. That would be Option #4 or Option #5 in my first post.

Like Shivam mentioned, some genre of music sounds good without a Sub and some others will be more "rich" with a Sub complimenting it.

Thanks,
John.

 

[Shivam]

Thanks for the input Shivam. I did follow your thread earlier regarding your Sub integration to your AP setup. If I remember correctly, you wanted a Sub just to get one song right ?

BTW, did you do RTA with REW or some other setup? I have a working REW setup already in place and have tried the RTA before. The results were not that satisfactory. So I thought of experimenting to fix some of the issues with a Sub integration and may be playing with some phase/location adjustment to nullify couple of unwanted peaks.

It seems like I should get the parallel connection option to integrate the Sub. This will let me switch the Sub off when ever I don't need it and still have the full range signal fed to my mains. That would be Option #4 or Option #5 in my first post.

Like Shivam mentioned, some genre of music sounds good without a Sub and some others will be more "rich" with a Sub complimenting it.

Thanks,
John.

It was for 3 songs that I ended up buying the two REL subs.

I used an integrated handheld RTA with spectrum display and cross checked the data with a dbx Driverack's built in RTA display using dbx RTA mic. Pink noise source was a test CD and pink noise generator inside the driverack.
The results were scary when I first saw them. Room is the biggest governing factor in any system's performance.

I used the room simulation mode of REW and some of my old knowledge on standing waves to position the subs and then set the cross over and gain for the subs based on the RTA readings.

I use the speaker level output from my amps to connect RELs which insures that I get the same amp sound signature on my subs as on the speakers. Since they are in parallel, I just have to switch off their power for getting them out of the system. The volume of the subs is also controlled by the preamp as the subs are placed after it (The gain control on subs is left undisturbed after calibration).

Some of the things that I learnt in the whole process :
1. Subs are not needed for most of the music
2. Most of us are used to listening to very high bass in our rooms (even though we don't know it)
3. Well integrated subs are never heard. Is is as if they are not actually being used.
4. Our ears adjust to the acoustics of the room the system is placed in and so too much of correction is of not much use.
5. When setting cross-over for subs, understand that the cross-overs are not of 'infinite' order and cover some more frequencies when they taper off. Speakers also play frequencies (at low levels) sometime well below their rated low frequency performance.

 

[Kannan]

I have my subwoofer placed bang in the middle of the L and R speakers which are incidentally bookshelves. My amplifier has a dedicated sub-out with LPF setting from 200 hz. The subwoofer is passive and in a sealed enclosure. It is powered by a mono block which has onboard phase adjustment, gain setting, bass boost and crossovers.
The auto calibration for the main amp works well but I have manually set it up.
The LPF is set at 80 with a 12db slope and sounds best when set in phase with the bookshelves. The sub volume has been adjusted with the gain control.
I also tried the Y cable way to feed directly from the pre to the mono instead of using the sub out from the main amplifier.
I could not notice any big difference.

I for one cannot live without a sub, be it bookshelves or towers.