SDA 2.3 No bass

tragusa3

First post: New to me SRS2.3 (non TL). If they were issue free, I would have paid better than fair. However, that is not how the story is going so far.

I immediately noticed lack of bass, so I started pulling drivers to make sure everything was correct. What appear as a pristine pair of speakers had actually been hacked up pretty good on the inside. The drivers were all different dates, 3 had been substituted for the incorrect driver. Probably typical after 40 years, but dang these were cherry on the outside. This picture with my big smile was before I started digging into them. The smile has left.




I was able to rob the correct drivers from my (very nice sounding) 1C's. This didn't solve the issue. So, using the internal wiring diagram, I went through every driver making sure it measured the correct resistance and the right wires were in the right places (including polarity).

I also used a battery to make sure the correct drivers were pushing or pulling. I didn't find any wiring issues (except one wire that Polk said should be red and it was actually white with a red marker).
At this point, I have spent 10 hours on them. I put them back together and fired up a track to disappointment.

Next step, I played test tones at various frequencies and used my SPL meter to see if it verified what I was hearing. It sure did. Below 80hz, volume drops like a rock.

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I'm including my worksheets I was using throughout all of this.

1. wire colors and polarity verified
2. resistance of each driver and driver type in correct location.
3. In/Out meaning which direction the driver moved with a battery test.
4. Overall cabinet resistance at the binding posts (4.4 ohms for both cabinets)
5. Chart of SPL readings at different frequencies (note: nothing audible at 40hz)
6. Pulled binding posts to verify internal connections and sanded jumpers clean.
7. I found a few spots on the rubber surrounds that were not glued well, so I repaired those. Cabinets hold seal to at least 3 seconds.

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I'm sort of guessing at this point. Does anyone a direction for next steps?

Anyone have a good link to a tutorial on testing capacitors? I can pull them and see if things are within tolerance?

Thanks to everyone that takes the time help with this mess. I enjoy the troubleshooting part of the hobby, but have to admit to being frustrated. On top, this could add hundreds into the investment that I was trying to do on a shoestring.

F1nut

The caps are way past their lifespan, but I can't say that is your problem.

How close to the wall do you have them?

tragusa3

Yes the caps are needed. I intend to rebuild them. I know caps will give improvements, but have they been known to make bass non-existent? I've tried placement in all available locations with no change in bass. My 1C's have strong bass in the same locations. I'm using an Emotiva XPA amp with approximately 400w/ch at 6ohm (note the cabinets are measuring 4.4 ohm at the binding posts).

F1nut

Ok, that doesn't tell me how far. They need to be 5 to 6 inches away from the wall with a half inch making or breaking it.

The 1C are bass thick.

Gardenstater

Are your sub-bass drivers functioning at all when you play those low tones? SDA Handbook says 4.0 Ohms from + to - binding posts. You have 4.3 or so. Could be your meter. It would be weird but what if someone disconnected the sub-bass drivers? Supposed to be 2 x 6513.

tragusa3

F1nut wrote: »

Ok, that doesn't tell me how far. They need to be 5 to 6 inches away from the wall with a half inch making or breaking it.

The 1C are bass thick.

I just measured and placed them 5" off the front wall. No difference in bass. The bottom register is currently 1/10th of what my 1C's are.

tragusa3

Gardenstater wrote: »

Are your sub-bass drivers functioning at all when you play those low tones? SDA Handbook says 4.0V from + to - binding posts. You have 4.3 or so. Could be your meter. It would be weird but what if someone disconnected the sub-bass drivers? Supposed to be 2 x 6513.

Hi George. I'm brand new to all of this. The sub bass drivers are the ones with the donut (MW6513), right? Those all measured 3.2 ohms. They are moving less than the other drivers (50% or so). How do I measure voltage at those? Put a tone on and measure the voltage the crossover is sending to them?

skipshot12

If the cabinet’s are well sealed, and you have 3-5 seconds on the leak down test, it would eliminate the cab and drivers sealing.

Almost sounds like the needed frequencies for bass are not being produced but, that’s a guess.

It may be time to look at the crossover?

No loose connections to all drivers?
Re-flow all solder connections on the crossovers?
After that all ok I’d start with the crossovers?

As previously said…. Caps are way past their life expectancy and replacing them is always a good idea.
Inductors rarely take a crap but I have seen an open in goofy situations.

skipshot12

All drivers are playing as they should?
All drivers have free movement with no magnet shift and voice coils rubbing?

tragusa3

The cabinets hold seal for 3-4 seconds. Not impressively well, but they do. They bump out equal to what I press on the PR, but almost immediately drop to 3/4 of that. They then hold the 3/4 distance for at least several seconds.

All drivers are free of VC rub. They all move in or out appropriately with the battery test. Mids and highs seem normal.

Gardenstater

Sorry I had a typo 4.0V should've been 4.0 Ohms. The ones with the donuts are supposed to be stereo drivers I believe (2 x 6511) and the other two in the 4 driver line array are supposed to be the sub-bass drivers which in the early 2.3s were MW6513 with heavier mass cones. Maybe if they were disconnected you would get a higher resistance of 4.3 or 4.4 like you are getting. They could be disconnected at the XO board. If you remove the passive radiators you can get a good look inside.

The schematic on record is weird in that someone crossed off Series/Parallel and it doesn't actually show the connection of the drivers. Maybe it is in another schematic.

pitdogg2

3-4 seconds is good for that test.

tragusa3

The MW6513's measure 3.2 ohms with nothing else connected to them. They move half as much as the other drivers when doing the pressure with the PR. Maybe this is normal due to the extra mass? I'm going to go back in and look at the crossover more closely.

F1nut

The ones with the donuts are supposed to be stereo drivers I believe (2 x 6511)

The donut drivers are MW6513.

F1nut

The cabinets hold seal for 3-4 seconds. Not impressively well, but they do. They bump out equal to what I press on the PR, but almost immediately drop to 3/4 of that.

They should not drop back that far, that fast. They should pop out and slowly recede about a quarter way back taking 3 to 5 seconds. When the PR is released they should recede quickly to their resting position

tragusa3

F1nut wrote: »

The cabinets hold seal for 3-4 seconds. Not impressively well, but they do. They bump out equal to what I press on the PR, but almost immediately drop to 3/4 of that.

They should not drop back that far, that fast. They should pop out and slowly recede about a quarter way back taking 3 to 5 seconds. When the PR is released they should recede quickly to their resting position

There are no obvious locations for leaking. I do have the material to cut out new gaskets for every hole in the cabinet. Start there? And, will minor leaking cause a 30db drop at 40hz?

Gardenstater

F1nut wrote: »

The ones with the donuts are supposed to be stereo drivers I believe (2 x 6511)

The donut drivers are MW6513.

Okay so the donuts are how they added the extra mass for the sub-bass drivers. Then the sub-bass drivers would be the upper and lower donut drivers in the 4 driver line array.

@tragusa3 Try disconnecting one of the terminals on each of the donut drivers and check the resistance across the + and - terminals at the binding posts. If you get the same values that you got before, then something is preventing those drivers from getting current.

JCL

Did you confirm the resistance between connectors matched those in the SDA handbook? That may tell you if there is a problem in the wiring or crossover. Below is what I had but it matches the handbook. Ignore the markup that was my measurements years ago.

tragusa3

JCL, I saw that chart, but no I haven't done this. I couldn't understand where it was asking me to measure?

F1nut

tragusa3 wrote: »

F1nut wrote: »

The cabinets hold seal for 3-4 seconds. Not impressively well, but they do. They bump out equal to what I press on the PR, but almost immediately drop to 3/4 of that.

They should not drop back that far, that fast. They should pop out and slowly recede about a quarter way back taking 3 to 5 seconds. When the PR is released they should recede quickly to their resting position

There are no obvious locations for leaking. I do have the material to cut out new gaskets for every hole in the cabinet. Start there? And, will minor leaking cause a 30db drop at 40hz?

Start with tightening the end cap nuts. There's 4 at the top and 4 at the bottom. You'll have remove the top drivers and the PR.

While you are in there it would not hurt to run a bead of sealant around the seams. Do not use RTV silicone. Also, make sure
all of the poly fill is above the PR.

The stock driver gaskets are supposed to be paper thin. Unless damaged there's no reason to replace them.

JCL

tragusa3 wrote: »

JCL, I saw that chart, but no I haven't done this. I couldn't understand where it was asking me to measure?

Pin #1 and pin #2 location are highlighted in yellow at the bottom of the page. They are where the pin blade interconnect plugs into the back of the speaker. The others measurements are taken off the binding posts.

tragusa3

F1nut: Will do. Tighten the nuts, construction adhesive on the inside seams.

JCL: Thanks, I understand and will do this.

audioluvr

Check your interconnect cable for continuity.

tragusa3

audioluvr wrote: »

Check your interconnect cable for continuity.

Done. Yes, continuity from pin to pin. Not from blade to blade. Bass response doesn't change with or without Interconnect. Thanks.

audioluvr

tragusa3 wrote: »

audioluvr wrote: »

Check your interconnect cable for continuity.

Done. Yes, continuity from pin to pin. Not from blade to blade. Bass response doesn't change with or without Interconnect. Thanks.

Then your sub base inductor is bad or has a bad connection. You should hear a significant difference between the IC plugged in and not.

xschop

In your 2nd pic, it looks like the driver connection tab detent is not engaged fully, possibly not making good connection.

I'd get rid of all plastic/pin connectors and hard solder all connections on the X-over and replace or re-crimp the fastons.

Gardenstater

I was looking at how black the male faston looks on the sub-bass inductor. It might just be the lighting in the photo....

It would be easy to measure the resistance/continuity of the sub-bass + return path to - binding post by disconnecting the + fastons at both drivers and measure from + terminal (or - since you already tested voice coil resistance) to - binding post (black). Should be the black one but it is possible for people to reverse the black and red plastic nuts (don't ask me how I know lol). Black should be on the R, Red on the L.

tragusa3

George, I'm trying to follow you, but I am literally a first timer. I had to Google was a "Fast-on" was and what an inductor looked like. And, when you say, "at the terminal", where exactly are you talking about?

Gardenstater

tragusa3 wrote: »

George, I'm trying to follow you, but I am literally a first timer. I had to Google was a "Fast-on" was and what an inductor looked like. And, when you say, "at the terminal", where exactly are you talking about?

No worries. Another term for faston is quick disconnect terminal or even a quickslide terminal. It is also the type of connectors that you probably have on your driver "terminals", unless they were still soldering when your speakers came out of the factory.



https://www.dormanproducts.com/p-24859-84546.aspx

https://www.autozone.com/stereo-speakers-and-audio/audio-terminal-and-connector/p/dorman-conduct-tite-quick-disconnect-audio-terminal/325950_0_0

pitdogg2

None of his are soldered on🤦🏻‍♂️

tragusa3

According to the Handbook, DCR checkpoints chart that JCL referred me to, I may be finding some differences.

Since I have no confidence in what I'm doing, I am attaching the chart with my readings. R2 and R5 are significantly different. I'm including the position of my probes when measuring R2. Am I doing it right?