SDA 2B lack of bass, but only 1 speaker

muncybob

I have noticed recently that the right channel is bass weak. Did the push test and it passes. Switched cables on the amp, sources, etc and have isolated it to def being the speaker. Where to look next?

gmcman

Make sure all the drivers are working and are in phase. You can use a 1.5V battery and briefly connect the battery to the speaker terminal with the speaker cables removed...if all in phase the speaker cones should move outward.

Other than that I would possibly suspect a loose connection on the large inductor coil.

Are the crossovers stock or have you worked on them, are you using the interconnect cable?

muncybob

I'll try the battery tonight. Yes, using the interconnect cable and yes the crossovers were worked on a few years ago, along with Larry's rings, etc.

TennMan

If it passes the battery test and the connection to the inductor coil is tight, check the crossover board for a cold solder joint. I few years ago a forum member had a similar problem that was caused by a cold solder joint.

muncybob

Yep, was out of phase. The mid drivers have no markings on them so I just took a best guess. When doing the battery test I was sure to connect the same wire to the negative speaker terminal and also to negative pole of battery. Drivers pull inwards on both speakers...is that right? I had thought they would push out. Do I now have both speakers uniformly out of phase? They sound good.....

westmassguy

plus to plus and minus to minus, drivers should move out

muncybob

So, with all of them(both speakers) moving out on the battery test....have I somehow managed to wire all of the mids out of phase or is it possible that I have reversed polarity at the speaker terminals? I guess I'll find out tonight.

pitdogg2

Well the real question is when was the last time you disassembled all the drivers? If its been a never then yes agree you need the check the speaker wire at both points amp and speaker.

DaveHo

5 way posts on the speakers should have the red on the left.

muncybob

I probably shouldn't admit this but, I'm not sure what I was drinking when I installed the upgraded crossovers but I managed to get the polarity reversed on BOTH speakers! Rather than pulling things out and resoldering I'm just gonna reverse the speaker cables...same difference right? I know this is gonna bug me so at some point I'll be doing it right.

While they always sounded better than before I always thought the bass was a bit muddy....much better now.

westmassguy

You may be really messing with the difference signal carried by the interconnect. The dimensional sections may not be functioning correctly.

muncybob

Why would that be? The crossover is getting the correct signal from the amp. The interconnect signal is fed from the crossover as are the tweets/mids?

TennMan

muncybob wrote: »

... I managed to get the polarity reversed on BOTH speakers! Rather than pulling things out and resoldering I'm just gonna reverse the speaker cables...same difference right?...

Could you be more specific about what you actually reversed? If it is just the input connection from the terminal cup you could just swap the black and red knobs on the terminal cup temporarily and enjoy your speakers until you decide to go back in for something else.

muncybob

Following the wires from the crossover last night I realized that the one marked + on the crossver board was connected to the binding post marked -...so I had the negative wire from the amp into that post. Visa versa for the other wire from the crossover. So in essence I was feeding the crossover the opposite signal that it was meant to receive. (still can't believe I did that!). The posts do not have a color code on them, have placed a piece of tape on the back of the speaker reminding me of which is + and - until I get the time to correct things internally. I hope I haven't caused any damage playing them out oh phase?

The mods I have not done is Blackhole behind the woofer/radiator or tl. What improvements could i expect if I did these(considering them since I'll have to pull things apart to correct my idiot mistake).

pitdogg2

you wont damage them doing that. They really don't care one way or another.

gmcman

muncybob wrote: »

Following the wires from the crossover last night I realized that the one marked + on the crossver board was connected to the binding post marked -...so I had the negative wire from the amp into that post.

Can you post a pic of your crossover board? Do you have the stock boards or Gimpods boards?

I'm curious how you have one of the wires incorrectly connected on the crossover and not two or more of them. It's possible to mount the white plastic connector upside down and get the polarity reversed.

muncybob

It's the original board. I didn't have just 1 wire wrong..positive and negatives were reversed.

gmcman

1976doc wrote: »

Battery test here???
If all your drivers move the same direction when connected to a AA battery you should be good.. if one of them doesnt move or moves in the opposite direction that would be your culprit..

The battery test was done, but all in the same direction is good if they move outward.

muncybob

"It's possible to mount the white plastic connector upside down and get the polarity reversed."

So, speaking of the white connector...I currently spliced the wires coming from this to the binding posts/interconnect cable. Is there somebody out there that would replace the existing spliced set up to be just 1 individual wire from each white connector "hole" to the posts? I would send you the white connector and the back plate that has the posts.

Schurkey

My internet time is now extremely limited. I didn't re-read the whole thread. If I misunderstand something, please forgive me.

MOST speakers, you connect them in reverse polarity, the drivers move the opposite direction they're supposed to. Some folks are sensitive to the reversed-polarity sound (The Wood Effect...right?) yet some folks are not sensitive to it.

HOWEVER, reversed polarity on SDA speakers results in NO SDA effect. SDA speakers MUST be connected in proper polarity or they do not function properly.

Am I wrong?

muncybob

I believe you are correct. They are sounding much better now. Bass is not muddy, mids are clearer and a much better soundstage. I DO have them in phase now, it's just that the Polk label on the back showing which post is positive and negative has to be reversed when connecting the speaker since I reversed the wires from the crossover to the connection at the binding posts. All speakers move outward now with the battery test, the push test has always been good...actually the mids retract only a very small distance while holding the woofer in and they will stay there a long time as long as pressure if kept on the radiator.

It's just that knowing I screwed up the wires is bugging me and I would like to correct and avoid a splice job.

TennMan

On page 32 of the SDA Handbook there is a test that determines if the SDA is functioning properly. You should do that test even thought the battery test indicates the woofers are in phase to make sure your 2Bs are working properly.

muncybob

Yep. It's also listed above in one of the "stickys". I will do this tonight but I'm fairly sure they are now working properly.

muncybob

Thanks for reminding me of those tests. As I expected, they passed all tests. I just now need to correct the internal wiring so the + and - on the crossover match the same on the binding posts. I would attempt this myself but I don't know how the wires connect to the plastic white terminal that attaches to the crossover board.

RandyCroissant

Can you take a picture of the crossover and the binding post cup so we can see what's up thanks. You should not be having so much trouble with this IMHO

TennMan

Maybe these photos will help. The interconnect cable connector has been changed in the second photo. Other than that your terminal cup should look the same.

RandyCroissant

To the OP this ^^^ is what you should have minus the speakon. Thanks Tenn.

muncybob

I was actually feeling good about things after running the tests last night until seeing that photo. I do not have(and do not recall ever having) a wire running from the + post to the interconnect. Just 3 wires from the crossover: interconnect, + and -.

I'll take pics if/when I open it up again.

TennMan

The photos I provide are for 2Bs with the pin/blade interconnect cable. If your interconnect cable is blade/blade the wiring connections might be different. I believe some early 2Bs used a blade/blade IC.

muncybob

Yep, blade-blade. So can somebody confirm that there are only 3 wires as I described? I have to believe it's so since they passed all the "tests". All that remains is to get the spliced wires replaced.

TennMan

If possible, you should post a photo of the back of your terminal cup. There are folks on here (smarter than me) who will recognize what you have and tell you if the connections are correct.