Help with Advents

[Newbie01812]

Hi all,

Apologies for probably being an annoying noob but I am struggling a little here and hopefully you will take pity given my circumstance.

So my Dad is in his 70’s and his health is pretty bad, so I was trying to give him a surprise to cheer him up. He always loved his Advents and for years has complained that they are just collecting dust in the attic.

Fast forward. I have gotten down the old speakers, and the foams had totally perished and the covers were looking kinda gross so I refoamed the woofers, got the cabinets looking beautiful again, re upholstered the covers and I thought while I had the woofers out I would recap the crossover.

I know they are NLA’s, they have the ‘Normal, Extended, Decreased’ switch and originally had the Unicon 13uf 50v and 1.0 Ohm 10w and 1.5 Ohm 10w resistors.

I educated myself as best I could and eventually went with installing a Dayton 12uF 250V Polypropylene and Dayton 1uF 250V Polypropylene in parallel.

After putting everything back together I hooked them up to my Pioneer SA-8500 and gave them a try.

So, they work…but they have way too much treble, so much so that the only way I can get them to sound half way normal is by using the ‘loudness’ switch on my amp…which I have never used before….but it’s the only way to pull some bass into the mix.

I have to admit, I have never heard a pair of loudspeakers, but given their reputation…I can’t think this is right?

Any advice would be hugely appreciated. I’ll be the first to admit I am no expert at this but I am generally ok with this kinda stuff and have recapped a few amps in my time without issue, but this is my first time not just changing like for like, or using poly caps.

Given I am trying to do something nice for my sick dad, I am hoping this wonderful community might offer me some help and advice as to why this is happening. On these caps take some time to break in? Am I missing something? Or did I just really mess up!? Here is an image of one of the crossovers post recap….

IMG-2331 hosted at ImgBB

Image IMG-2331 hosted in ImgBB

ibb.co

 

[rmeade]

Greetings and welcome

first you should confirm that the woofers are working, put your ear to a tube (like that used by paper towels) and the other to the woofer (s) play some music. Make sure that there are no shorts to the wiring and such.

The advent is an acoustic suspension speaker. The woofer works by compressing the air and using this to 'spring back'. The cabinet needs to be sealed well; the two drivers (woofer, tweeter) need to be sealed at their seating to the cabinet. The cabinet interior perimeter joints (where the walls and back intersect) need to be tight and leak free. You can use some cheap calking here. The speakers were designed to have insulation inside the cabinet - that fills the cabinet. You seem to have some foam there, in the picture, and this might not be enough.

Why don't you take a picture of the foam surrounds that you installed. These could be an issue too.

Don't fret, you are close.

 

[swechsler]

Yeah, my guess would be a problem with the refoaming as well. What foam did you use? How did you center the cones while you were gluing the foam? Check to make surround is fully glued all the way around. And while I agree with @rmeade that the cabinet seal is important, acoustic suspension speakers were rarely perfectly sealed; you're talking about a wood box, after all, so don't sweat this too much. With the woofer playing some deep bass, run the back of your hand along any joints in the cabinets and where drivers are installed; if you feel any strong blasts of air then that area needs to be sealed better.

 

[Newbie01812]

Well first of all thank you so much for the immediate answers….and also the woofer mounting would never have been my first thought! @rmeade i am pretty sure the foam is good, I did remove about 2/3 of it while I recapped the crossover but took pictures and replaced it exactly as it came out, it’s packed in there pretty tight.

Let me try tightening the mounts and checking for leaks and I will report back.

 

[Newbie01812]

Also when it comes to the refoaming I am pretty confident here. I used a kit from simply speakers and they were perfectly centered.

 

[Newbie01812]

Ok so update, tightened the mountings….to be honest they were pretty tight already so I’m pretty sure nothing much changed there.

Played some music through them…woofers are definitely working, no air escaping through the foam or the cabinet.

Still just sounds like there is way too much mid to treble.

There is bass there but it sounds so hidden in the mix, it’s like having the treble turned to max at all times so as you increase the volume it become super obnoxious.

 

[swechsler]

Are you sure the tweeters are original? You mentioned the tweeter output switch but not what setting you have it on. Does changing its position have any effect?

One thing I would try is to disconnect the tweeters and see if the woofers are actually performing well on their own, just not at the correct output level. That is, does low bass come through at the same level as midbass? You can use a frequency generator app to test this. Try comparing, say, 80 hz to 320 hz.

 

[Newbie01812]

I’m am pretty certain they are original @swechsler my old man has never mentioned changing anything and then I opened up the cabinets it looked like they had never been touched before.

Right now I have them on ‘Decreased’ but I have tried every setting, it makes a mild difference but not huge.

I can definitely try disconnecting the tweeters later this week if you think that’s worthwhile. I may need your help performing the test you suggested.

I’m really stressed here all, feel like I have ruined my dad’s prized speakers.

 

[swechsler]

To test without the tweeter, you just need to disconnect one wire from the tweeter; then reinstall them back in the speaker so it doesn't interfere with the woofer's performance.

Another test you can try is: with the speaker fully assembled, push the woofer cone in (apply pressure on either side of the cone, don't press on the dust cap). It should (relatively) slowly return to its rest position. Then remove the woofer, or the tweeter, from the cabinet and repeat the test. When it's not in a sealed cabinet, the woofer cone should spring back immediately.

Don't stress out here, it's unlikely you've done any permanent damage. Worst case, replacement drivers are commonly available on the used market, but I don't think you're going to have to go that far.

 

[Newbie01812]

Thanks man, I really hope so.

Here’s what may possibly be a really dumb question….is there any chance I wired the woofers wrong? There was no markings on the ears for + and - but is there a right and wrong polarity??

 

[swechsler]

It's possible you wired one of them out of phase, but that's easy to check by just listening to one speaker at a time. If you wired both the same way then that's probably not the problem.

 

[Newbie01812]

But that would be the speaker itself right? I was asking if specifically the woofer has a designated pos and neg? I know the connections from the amp to the speaker posts are correct

 

[kermit z]

But that would be the speaker itself right? I was asking if specifically the woofer has a designated pos and neg? I know the connections from the amp to the speaker posts are correct

Yes check the woofer inside the cabinet and make sure they are connected correctly. It can easily get swapped. Now, I have refoamed a number of OLA's, and no NLA's but the OLA woofers have a seal that has to be replaced usually when placing the speaker back into the cabinet. I used Plumber Putty on the last set I refoamed, heck maybe on all I have done, it's been awhile.

 

[swechsler]

But that would be the speaker itself right? I was asking if specifically the woofer has a designated pos and neg?

It does, but the difference in sound would be minimal unless you wired the woofers in each speaker differently. That's because when they are wired out of phase (left vs. right), either the woofer or the entire speaker, the signals can cancel each other out, and the bass can be diminished. That's why I recommended trying just one speaker. If both woofers are wired out of phase relative to their design (but in phase relative to each other), it might be audible, especially in the frequencies where the woofer crosses over to the tweeter, but it's unlikely to cause the problem you're experiencing.

I don't know the Advents specifically, and I couldn't find a pic of the internal wiring, but in most speakers, the 0 terminal would be connected directly to the unmarked or '-' terminal on the driver (and when I say "directly", I don't mean that the wire will always physically run directly from the terminal, but there should be no electronic components between the driver and the terminal, so if you did a resistance reading, you'd get 0Ω between 0 and the - wire), and the other wire goes to the terminal with the '+' or red mark. This isn't a hard and fast rule, but the Advent crossovers are relatively simple, so it should apply in this case.

 

[f0427ea]

But that would be the speaker itself right? I was asking if specifically the woofer has a designated pos and neg? I know the connections from the amp to the speaker posts are correct

Yes they do or at least should

embossed next to the tabs as in this picture


Or marked in some way as in this picture

 

[f0427ea]

Simply switching the positive and negative wires connecting the woofer in one of the speakers would solve the out of phase question.

 

[f0427ea]

The woofer and tweeter need to be wired in phase.

 

[kmagnuss]

I have the same speakers and they have quite a lot of bass. I'd try the following (as others have recommended):
-You may have the woofers wired backwards to each other... you can quickly test this by just bouncing back and forth with your balance knob... if there's more bass when just one speaker is playing you have a speaker out of phase.
-The positive side is shown in a picture above... it's the left terminal when the speaker is facing down.
-Make sure your tweeters are wired properly also, but this won't effect the bass output
-How many foam/sponge squares do you have in each speaker? There should be 4 in each. This matters and definitely changes the amount of bass. If you don't have all 4 in each speaker you will need to add some or some fiberglass. I read a review where a guy had the original foam in one speaker and put in fiberglass in the other and the one with the foam produced substantially more bass (in his application).

Best of luck. I'm going to be re-capping and swapping the resistors on mine this weekend, so if you need any pictures while they're apart just let me know.

-Mag

 

[drumbum]

@Newbie01812

The NLA's are fairly "bright" from the factory. Wall to wall carpet and plush upholstery and draperies were popular at the time, which led to the redesign.

They need to be switched to the "decrease" setting for normal rooms.

The Poly caps are already low esr and in parallel lowers it even more, hence the overly bright tweeter.

 

[rmeade]

The refoaming job looks nice. Is there a seal in place between the speaker frame and the cabinet for all four drivers?

Sealing cones Advents and BA's

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