help! NLA tweeter issue (i think...)

[worldwidehoodoo]

greetings! i'm a first timer here, as you can see. i did my best to wade through old topics to form a coherent question...my apologies if i overlooked any obvious info.

i acquired a pair of new large advents a few years back (A3 78620 & A3 81047, respectively.) i bought them from the original owner, who took excellent care of them. i know he had the foam surrounds redone, and the dustcaps look newish too...he may have had them re-coned altogether, but i don't remember the exact story.

anyway, one speaker always sounded way "duller" than the other. for a long time i figured that this was due to my room setup (400sqf efficiency = speakers 2 ft. apart, 2 inches from back wall, with all kinds of craziness on the sides.)

once i got into a bigger place (ah! to have a bedroom...) the problem persisted.

i re-did both crossovers with sonicraft caps and resistors. this dramatically improved the problem and overall performance, but the basic issue remains: one speaker just sounds more "alive" than the other.

tonight i tested the woofers and tweeters with a multimeter. here's what i got:

"bad" speaker:

tweeter: 2.2-2.3

woofer: 4.3

"good" speaker:

tweeter: 2.9-3.0

woofer: 4.4-4.5

now, i must say that i have little to no knowledge of how electronics actually work. if you give me a soldering iron and some components i can "follow the recipe", but that's about it. i'm pretty sure i'm using the multimeter correctly, though it was $18 at walmart and should probably have the "fisher price" logo on it compared to most others.

SO....if i am testing this all correctly....do i need a new tweeter? can tweeters even be repaired? is there anything else i should test?

i'd really appreciate some help, and i'd be happy to provide more info about my setup/listening environment if needed.

thanks so much

-mike

[Pete B]

greetings! i'm a first timer here, as you can see. i did my best to wade through old topics to form a coherent question...my apologies if i overlooked any obvious info.

i acquired a pair of new large advents a few years back (A3 78620 & A3 81047, respectively.) i bought them from the original owner, who took excellent care of them. i know he had the foam surrounds redone, and the dustcaps look newish too...he may have had them re-coned altogether, but i don't remember the exact story.

anyway, one speaker always sounded way "duller" than the other. for a long time i figured that this was due to my room setup (400sqf efficiency = speakers 2 ft. apart, 2 inches from back wall, with all kinds of craziness on the sides.)

once i got into a bigger place (ah! to have a bedroom...) the problem persisted.

i re-did both crossovers with sonicraft caps and resistors. this dramatically improved the problem and overall performance, but the basic issue remains: one speaker just sounds more "alive" than the other.

tonight i tested the woofers and tweeters with a multimeter. here's what i got:

"bad" speaker:

tweeter: 2.2-2.3

woofer: 4.3

"good" speaker:

tweeter: 2.9-3.0

woofer: 4.4-4.5

now, i must say that i have little to no knowledge of how electronics actually work. if you give me a soldering iron and some components i can "follow the recipe", but that's about it. i'm pretty sure i'm using the multimeter correctly, though it was $18 at walmart and should probably have the "fisher price" logo on it compared to most others.

SO....if i am testing this all correctly....do i need a new tweeter? can tweeters even be repaired? is there anything else i should test?

i'd really appreciate some help, and i'd be happy to provide more info about my setup/listening environment if needed.

thanks so much

-mike

I usually find the NLA tweeters to be about 2.2 - 2.5 ohms so

you are in the ball park. I don't recall on these tweeters, since

I don't have one in front of me, but often the current passes

through a rivet that holds on the terminal lug. The rivet is

often brass which can corrode. You can measure on the

other side of the rivet and see if you get a different reading

to see if it is worth cleaning up around the rivet and soldering

across it to avoid any problem with corrosion.

Otherwise I would find a replacement tweeter.

[Doug G.]

Welcome, Mike.

Another thing you can do is connect the "good" tweeter directly to a music source (turntable/amp) with the volume and bass all the way down. Now, turn up the volume just until you hear music from the tweeter. Disconnect that tweeter and connect the "bad" one.

These were made to fairly tight specs. so you should hear very close to the same output from the "bad" tweeter as the "good" one.

If not, assume there are windings shorted or whatever and you need a replacement.

Doug

[worldwidehoodoo]

I usually find the NLA tweeters to be about 2.2 - 2.5 ohms so

you are in the ball park. I don't recall on these tweeters, since

I don't have one in front of me, but often the current passes

through a rivet that holds on the terminal lug. The rivet is

often brass which can corrode. You can measure on the

other side of the rivet and see if you get a different reading

to see if it is worth cleaning up around the rivet and soldering

across it to avoid any problem with corrosion.

Otherwise I would find a replacement tweeter.

thanks!

i measured on the other side of the rivet, and the reading was actually lower. i'm becoming a bit suspect of my meter...it may just need a new battery. the numbers on the display go all over the place and then finally settle on a reading.

i always thought that 3 ohms was the proper reading for these tweeters, so i guess i'm wondering what constitutes "out of spec"....is 2.3 not that different from 3.0?

btw i'm going through the thread for the magic box mod....probably some dumb questions coming your way from me soon!

Welcome, Mike.

Another thing you can do is connect the "good" tweeter directly to a music source (turntable/amp) with the volume and bass all the way down. Now, turn up the volume just until you hear music from the tweeter. Disconnect that tweeter and connect the "bad" one.

These were made to fairly tight specs. so you should hear very close to the same output from the "bad" tweeter as the "good" one.

If not, assume there are windings shorted or whatever and you need a replacement.

Doug

this sounds fun...

the only source is my HH Scott LK 48 integrated...so i assume you mean that i should hook up the speaker wires directly to the tweeter? trying to not blow myself up here...

i suppose i should begin my search for a new tweeter. is there a most popular drop-in replacement currently in production, or is it best just to buy the originals on ebay?

[worldwidehoodoo]

forgot to ask:

what should the inductors read, and do i need to remove them from the circuit for an accurate reading? i did some serious listening today with a wide range of music, and noticed that some of the difference is in the low end as well.

thanks

-mike

[Pete B]

forgot to ask:

what should the inductors read, and do i need to remove them from the circuit for an accurate reading? i did some serious listening today with a wide range of music, and noticed that some of the difference is in the low end as well.

thanks

-mike

The woofer inductor has a DC resistance of about .36 - .38 ohms,

as you can see in section 3.1 here:

http://baselaudiolab.com/ADVENT_LA_XO.html

Just remove the woofer connection and as long as only one lead is connected

to the XO you will get a good reading.

[Pete B]

thanks!

i measured on the other side of the rivet, and the reading was actually lower. i'm becoming a bit suspect of my meter...it may just need a new battery. the numbers on the display go all over the place and then finally settle on a reading.

i always thought that 3 ohms was the proper reading for these tweeters, so i guess i'm wondering what constitutes "out of spec"....is 2.3 not that different from 3.0?

btw i'm going through the thread for the magic box mod....probably some dumb questions coming your way from me soon!

this sounds fun...

the only source is my HH Scott LK 48 integrated...so i assume you mean that i should hook up the speaker wires directly to the tweeter? trying to not blow myself up here...

i suppose i should begin my search for a new tweeter. is there a most popular drop-in replacement currently in production, or is it best just to buy the originals on ebay?

Actually, as I stated earlier 2.2 to 2.5 ohms is what I usually read for NLA

tweeters so it is odd that your bad one is actually in range. Again if the

reading is different on the other side of the rivets you should clean them

up and solder across. Also check the resistors and switch in the crossover,

solder any crimped connections.

It is normal for the meter reading to change until it determines

the resistance, however make sure that the connections are clean and

that it is zeroed.

[worldwidehoodoo]

The woofer inductor has a DC resistance of about .36 - .38 ohms,

as you can see in section 3.1 here:

http://baselaudiolab.com/ADVENT_LA_XO.html

Just remove the woofer connection and as long as only one lead is connected

to the XO you will get a good reading.

i disconnected the woofer and desoldered one of the inductor leads from the XO. i couldn't get any type of reading, but i think this is either a problem with my meter or me (most likely me!)

i'm using an ESUN DT830 digital multimeter, which under the "ohm" setting has stops for 200, 2000, 20k, 200k, and 2000k. i tried them all and got nothing.

again this is probably a malfunction with yours truly, as i assume if the inductor was "dead" the woofer wouldn't make much sound. am i wrong?

Actually, as I stated earlier 2.2 to 2.5 ohms is what I usually read for NLA

tweeters so it is odd that your bad one is actually in range.

i understand that, but i don't understand why if one reads 2.9, and the other reads 2.3 they are both in "in spec". is the 2.9 out of spec? i'm asking this more for my own curiosity than anything else...just trying to wrap my head around the range of readings that are considered "normal". if the typical reading is 2.2 - 2.5 ohms, what reading would give you pause?

again, i'm just curious/"thinking out loud" so to speak....

thanks so much for your help/advice. i'm circling the wagons on the BSC box as we speak, so i may bug ya some more!

[Pete B]

i disconnected the woofer and desoldered one of the inductor leads from the XO. i couldn't get any type of reading, but i think this is either a problem with my meter or me (most likely me!)

i'm using an ESUN DT830 digital multimeter, which under the "ohm" setting has stops for 200, 2000, 20k, 200k, and 2000k. i tried them all and got nothing.

again this is probably a malfunction with yours truly, as i assume if the inductor was "dead" the woofer wouldn't make much sound. am i wrong?

i understand that, but i don't understand why if one reads 2.9, and the other reads 2.3 they are both in "in spec". is the 2.9 out of spec? i'm asking this more for my own curiosity than anything else...just trying to wrap my head around the range of readings that are considered "normal". if the typical reading is 2.2 - 2.5 ohms, what reading would give you pause?

again, i'm just curious/"thinking out loud" so to speak....

thanks so much for your help/advice. i'm circling the wagons on the BSC box as we speak, so i may bug ya some more!

The woofer inductor is probably too low for you to read

on a 200 ohm full scale meter. I doubt there is a problem

with it. There was no need to desolder it, just pull the red

positive woofer lead - assuming you still have the push on

terminals.

I said you were in the ball park, at least the other tweeter

is not an open circuit. I do not think that 2.9 ohms is normal

but I do not have a large sample set and all of these speakers

have seen production changes so who knows? What reading

do you get, for each one, going on the other side of the rivets?

Also try to measure all the resistors in case one has gone out

of spec. You can just pull the yellow lead from the tweeter to

measure the resistors and set the switch to decrease.

Also, does your meter zero reliably? Not to be critical but it

could be operator error.

You're welcome and I hope you do try the BSC.

[worldwidehoodoo]

The woofer inductor is probably too low for you to read

on a 200 ohm full scale meter. I doubt there is a problem

with it. There was no need to desolder it, just pull the red

positive woofer lead - assuming you still have the push on

terminals.

I said you were in the ball park, at least the other tweeter

is not an open circuit. I do not think that 2.9 ohms is normal

but I do not have a large sample set and all of these speakers

have seen production changes so who knows? What reading

do you get, for each one, going on the other side of the rivets?

Also try to measure all the resistors in case one has gone out

of spec. You can just pull the yellow lead from the tweeter to

measure the resistors and set the switch to decrease.

Also, does your meter zero reliably? Not to be critical but it

could be operator error.

You're welcome and I hope you do try the BSC.

ha ha! did you know that my middle name is "operator error"?

i don't think that 2.9 is normal, either. weird thing is that the "abnormal" speaker sounds better!

i've replaced the caps and resistors in both XOs..the only original remains are the inductors and the switches. all new components are brand new from sonicraft...tested them all before installing, and they are all soldered in the right place.

now, in the back of "bad" driver there is some weird residue/oxidation of some sort...though it looks like it's been there a long time. regardless, it tests in spec.

as for the meter....it never shows zero in the ohm setting...it has a 1 at the far left, and then the decimal moves depending on which setting you choose. if you can recommend a good, cheapo meter that does what it should for this application, i'm all ears.

NOW....ONTO THE BSC!

i've looked through the thread, and it looks like something i can build pretty easily. i'm pretty excited about it, to tell you the truth!

i'm running an HH scott lk-48 integrated (48-watt, 20wpc rms) into the NLAs. it has a tape monitor, so we should be good to go.

my question: should i do the 2.2k version, or the 4.7k?

it looks like another person in the thread made a box with switches for each db step. i'd really like to do this, but without a picture to go from it would be tough for me. i'd have to sit down and actually learn how to wire something up like that, and i don't have the time do that right now. SO, unless you happen to have such a picture....which db step would be the most appropriate for the system i'm running?

thanks again! can't wait to try out the mod.

[Pete B]

ha ha! did you know that my middle name is "operator error"?

i don't think that 2.9 is normal, either. weird thing is that the "abnormal" speaker sounds better!

i've replaced the caps and resistors in both XOs..the only original remains are the inductors and the switches. all new components are brand new from sonicraft...tested them all before installing, and they are all soldered in the right place.

now, in the back of "bad" driver there is some weird residue/oxidation of some sort...though it looks like it's been there a long time. regardless, it tests in spec.

as for the meter....it never shows zero in the ohm setting...it has a 1 at the far left, and then the decimal moves depending on which setting you choose. if you can recommend a good, cheapo meter that does what it should for this application, i'm all ears.

NOW....ONTO THE BSC!

i've looked through the thread, and it looks like something i can build pretty easily. i'm pretty excited about it, to tell you the truth!

i'm running an HH scott lk-48 integrated (48-watt, 20wpc rms) into the NLAs. it has a tape monitor, so we should be good to go.

my question: should i do the 2.2k version, or the 4.7k?

it looks like another person in the thread made a box with switches for each db step. i'd really like to do this, but without a picture to go from it would be tough for me. i'd have to sit down and actually learn how to wire something up like that, and i don't have the time do that right now. SO, unless you happen to have such a picture....which db step would be the most appropriate for the system i'm running?

thanks again! can't wait to try out the mod.

My meters are Fluke and unfortunately they are not inexpensive,

but they are the best IMO.

I'm hearing fairly good things about Mastech but I have no experience with them:

http://www.diyaudio.com/forums/equipment-t...tml#post2144876

That is a tube amp I take it? If so you want a much

higher impedance. Do you have a link to the schematic?

More power is also better, say 50 to 100W

[worldwidehoodoo]

My meters are Fluke and unfortunately they are not inexpensive,

but they are the best IMO.

I'm hearing fairly good things about Mastech but I have no experience with them:

http://www.diyaudio.com/forums/equipment-t...tml#post2144876

That is a tube amp I take it? If so you want a much

higher impedance. Do you have a link to the schematic?

More power is also better, say 50 to 100W

yes, the hh scott lk 48 is an integrated tube amp.

schematic:

http://hhscott.com/pdf/fs/222C-C1.JPG

[Pete B]

yes, the hh scott lk 48 is an integrated tube amp.

schematic:

http://hhscott.com/pdf/fs/222C-C1.JPG

You've got tubes with no cathode followers which indicates that

it is a high Z circuit. Use the 2.2K design, or the values from the

tables but multiply the resistors by 10, and divide the cap values

by 10 which will raise the impedance to 22K which is a good

match for tube circuits.

[worldwidehoodoo]

You've got tubes with no cathode followers which indicates that

it is a high Z circuit. Use the 2.2K design, or the values from the

tables but multiply the resistors by 10, and divide the cap values

by 10 which will raise the impedance to 22K which is a good

match for tube circuits.

thanks, and sorry for the belated reply...rough weekend!

if i multiply and divide the components i come up with following for a 4db attenuation:

R1 = 22 K, C1 = .001

R2 = 35k, C2 = .01

is this correct?

would it be worth it to also build one with the original values to compare, or will the "multiplied" version be way better?

thanks again.

-mike

[Pete B]

thanks, and sorry for the belated reply...rough weekend!

if i multiply and divide the components i come up with following for a 4db attenuation:

R1 = 22 K, C1 = .001

R2 = 35k, C2 = .01

is this correct?

would it be worth it to also build one with the original values to compare, or will the "multiplied" version be way better?

thanks again.

-mike

Your values are correct.

No there is no reason to build one

with the original values - it is just

not right for a tube circuit such as

the one you're using.

Build it if you want to try a SS amp.