[John B]

 What's that you're saying neighbor?  

Got two 10" Rocket subs coming in for review on Friday.  Going to use the tape out on my tube preamp and adjust for volume on the sub amp.  Don't know how well this is going to work, but I thought I'd give it a try.  Now the thing is...how do I judge how good these subs are?  Looks like I may have to pay Big B a visit to get duly educated to the facts of great sub lore

[Charles Calkins]

Yo Beav:
  As sharp as you are when it comes to audio gear I'm sure you don't need any advice from anybody.

                       Cheers
                       Charlie

[John B]

Yo Beav:
As sharp as you are when it comes to audio gear I'm sure you don't need any advice from anybody.

Cheers
Charlie

You really think so Charlie?  I don't know, I consider myself very much a rookie at all this myself.  I've experienced a decent selection of gear from SS to tubes from dynamic drivers to ribbon's but I'm no where near versed enough in audio knowledge to consider myself an expert.   I know what I like in sound reproduction in my rig, but that's the extent of it.  I have no where near the technical knowledge of most in the Industry and even my fellow enthusiasts.   I always look for good advice, I'd be a fool not to.  But who knows, maybe I'm starting to come across as a know it all; well, about the only thing I really know it alla bout  is what I like in the components that cross my path in my system.  Beyond that it's all discovery and investigation, which I think is what we are all about.  

Regards,

John

[Charles Calkins]

Beav:
  I've read articles by you in Positive-Feedback. You are being very modest. I'd listen to your advice any day of the week.

                                      Cheers
                                       Charlie

[warnerwh]

Talking to B about bass can't hurt too many people. He's certainly an expert on the subject and how to do it right.  Best of luck on your review John.  I'm sure it's difficult to have equipment sent to your house to listen to

[John B]

I'm sure it's difficult to have equipment sent to your house to listen to

You don't know my neighbor, it's a bit more risky than you think  

[ctviggen]

I think of all the things to review (well, other than cables, that is, where the differences are minute), subs might be the hardest things to review.  I have an SV sub, and in my other (rental) house, the thing shook the whole house.  And it wasn't in a corner.  In my new house, where the system is in the basement, the difference was phenomenal -- even in a corner, there just wasn't the tactile presence that the old setup had.  Even now, with two VMPS largers AND the SV sub, I still don't get the same "oomph" that the single SV sub had in my old house.  Part of this is the fact that I no longer up the sub level by 3dB, and part has to be the room.  There's a lot involved with subs -- getting them to blend in with your system; are they best for music or movies or are they good at both?; placement issues to get the best overall response; room modes; etc.

[John B]

Warner,

My PM ability here on AC was removed last year, so I'll answer your message here.  The Rdes will be coming later, as they are out of stock presently.

[doug s.]

 What's that you're saying neighbor?  

Got two 10" Rocket subs coming in for review on Friday.  Going to use the tape out on my tube preamp and adjust for volume on the sub amp.  Don't know how well this is going to work, but I thought I'd give it a try.  Now the thing is...how do I judge how good these subs are?  Looks like I may have to pay Big B a visit to get duly educated to the facts of great sub lore

john, i would strongly recommend *against* using the tape out for yer subs.  this will mean having to separately adjust the subs' wolume every time ya wanna adjust the mains' wolume.  while best results would be to use an active x-over between subs & mains, until you do this, you will be better served by using a splitter from yer preamp line outs to feed yer main amp & the subs.  then, when the proper sub wolume is dialed in, it will be in sync w/the mains whenever the preamp wolume control is adjusted.  the only possible issue w/hooking your system up this way this is that it will effectively double the preamp's output impedence that your amps see...

doug s.

[John B]

Doug,

This type of splitter, which I assume will have a 2 rca male/4 rca female config., where would I get one?  The output imp of my preamp is 500 ohms, the input imp of my amps is 412K Ohms.  Will this work?

[John B]

Doug,

This what you're talking about with an active crossover?

http://www.crutchfield.com/S-hfAv2EkmJD4/cgi-bin/ProdView.asp?wm=fp&I=20603KX2&g=82600

[doug s.]

john, re: splitters, i am talking about something like this:


http://www.partsconnexion.com/catalog/connectors.html

as long as your output impedence is at least 10 times smaller than the amp's input impedence, you should be fine.  w/500ohm output impedence (effectively doubled w/the splitter to 1kohm, this is so much smaller that the 412kohm input impedence of yer amp, that you will be fine.

re: x-over, if you can't get something like a marchand x-over, i wouldn't bother - i'd yust run it as i described prewiously, w/a splitter.  the x-over from crutchfield yure showing would likely work (and it likely needs 12vdc to be powered, as it's for car stereo), but it also likely will be quite veiled sounding...  if ya really wanna try an active outboard x-over, & don't wanna splurge on something like a marchand (which can be found every so often used for ~$300), ya may wanna try a pro-audio unit from dbx, behringer, art, etc...  these can usually be had from pro-audio stores for ~$150 new.  and, the also show up a lot on places like ebay...  ashly also makes pro-audio x-overs that are supposedly among the best for pro-audio stuff, but they are a bit more $$$.  still may be able to find a current used model on ebay for $200 or less.  i have never tried the pro-audio x-overs...

doug s.

[John B]

I picked up two of Radio Shack's top of the line   Y-Adapators.  Now for the tricky part; setting the crossover on the sub.   It'll all depend on my monitors in room response; I'd bet 50hz is where I'll end up.

+/- 1dB: 70Hz - 18kHz
-3 dB, typical in-room: 45Hz - 20kHz

Thanks Doug!

[doug s.]

good luck, john.  50hz is definitely a good place to start.

fyi, tho i am sure those rat-shack adapters will work, the "fancy" adapters from audioconnexion are only $7.50/pair...

doug s.

I picked up two of Radio Shack's top of the line   Y-Adapators.  Now for the tricky part; setting the crossover on the sub.   It'll all depend on my monitors in room response; I'd bet 50hz is where I'll end up.

+/- 1dB: 70Hz - 18kHz
-3 dB, typical in-room: 45Hz - 20kHz

Thanks Doug!

[John B]

Doug,

To my ears things sound pretty good with the two subs hooked up in the manner decided on.   However I've been questioned about whether this combo is creating sub cancellation?  I turned off one sub last night to see if the bass picked up but all's I heard was a lessening of the fullness of the sound in general.   I only measured the subs by themselves yesterday, using the onboard equalizer to tame the 35hz bump I found via the Rives Test tone cd disc.  I still have a nasty suck out at 50hz I need to deal with when I get the Rdes.   But so far so good, I feel there are improvements with this setup, though until I a/b with my BOMB "bass booster" (w/subs offline) I wont' be able to define gains vs losses.

[zybar]

Doug,

To my ears things sound pretty good with the two subs hooked up in the manner decided on.   However I've been questioned about whether this combo is creating sub cancellation?  I turned off one sub last night to see if the bass picked up but all's I heard was a lessening of the fullness of the sound in general.   I only measured the subs by themselves yesterday, using the onboard equalizer to tame the 35hz bump I found via the Rives Test tone cd disc.  I still have a nasty suck out at 50hz I need t ...

How big is the suckout?

Don't expect the Rdes or any of the digital correction system to fix a big suckout.   You can add a little boost, but not much more than a few db's.  Anything more than that will actually make things worse and not better.

Also, make sure you have headroom on your sub amp before applying the boost.

George

[John B]

How big is the suckout?

It's a 8db difference.  

[doug s.]

Doug,

To my ears things sound pretty good with the two subs hooked up in the manner decided on.   However I've been questioned about whether this combo is creating sub cancellation?  I turned off one sub last night to see if the bass picked up but all's I heard was a lessening of the fullness of the sound in general.   I only measured the subs by themselves yesterday, using the onboard equalizer to tame the 35hz bump I found via the Rives Test tone cd disc.  I still have a nasty suck out at 50hz I need to deal with when I get the Rdes. But so far so good, I feel there are improvements with this setup, though until I a/b with my BOMB "bass booster" (w/subs offline) I wont' be able to define gains vs losses.

yes, this bass cancellation issue was talked about in another thread, where i commented two subs is always better than one.  until that thread, i've never heard about this.  and, ime, i've never heard one sub be anywhere near as good as two...  any room issues are much easier to deal with, using two subs than one, imo.  and, you will certainly get bass cancellation electronically, if you sum a stereo signal into mono.

re: room bass boost/suckout, since you have a db meter, you can experiment w/placement.  george is correct re: trying to fix suckouts w/equalization.  to help w/room node issues, try, for example, to *not* have the subs symmetrically placed in the room.  ie: if the left sub is 3' from the left wall, try 2'-6" or 3'-6" for the right sub from the right wall.  (this can also work w/monitors, either w/or w/o subs, btw...)

doug s.

[John Casler]

  re: room bass boost/suckout, since you have a db meter, you can experiment w/placement. george is correct re: trying to fix suckouts w/equalization. to help w/room node issues, try, for example, to *not* have the subs symmetrically placed in the room. ie: if the left sub is 3' from the left wall, try 2'-6" or 3'-6" for the right sub from the right wall. (this can also work w/monitors, either w/or w/o subs, btw...)
...

If I'm not mistaken, isn't your room asymetrical already JB?

Isn't the left sub closer to the wall, and the right has a kitchen opening etc.?

[John B]

If I'm not mistaken, isn't your room asymetrical already JB?

Isn't the left sub closer to the wall, and the right has a kitchen opening etc.?
_________________

The left sub is at the only true corner in the front of the room, the right sub is off of the entrance way hallway.   The room is 10' wide by 24' long.  After a full day of experimenting the best sub placement I came up with was left sub 3' behind left speaker flush to the left front corner, right sub same distance back flush against a bass trap, in the right intersection corner that has the hallway going to the front door.   Crossover that worked best, with the subs not be audible, but the bass clearly enhanced, was 50hz.   Now with the subs and the main speakers in the mix, my 50hz suck out was gone.  I'm fairly flat from 20hz to 60hz, then I get some peaks from there on up.  I may try to raise the crossover point on the subs to attempt attenuatio of those frequencies, but I doubt it will sound as good.   I did find that the BOMB (bass filter/booster) on the mains was a must.   Things simply sound flatter and mushier without it.   So, with BOMBs in, and the subs on line at a 50hz crossover, we have much more fullness and extension to all frequencies.  A definite keeper at this point.