testing a crossover

unable to access your crossover photos
https://antenaview.xyz/

PM me,  I'll answer when I can, but there are things to check that have not been mentioned. This can be figured out.  It may well be a driver problem, if not, I can draw new crossover schematics for you with a few improvements if you can build them.  

Hi Tim,so sorry i havent gotten back  to you,ive been trying to to fix this problem online with another guy,but for me,my end,my laptop is very old and slow,and have been waiting to receive a new one from the UK,and it all takes time,living in Bulgaria,thank you so much or your offer,it is very much appreciated, I wish you all the luck in the world,with your new job and thank you again for your amazing offer.   kind regards mk.

@likklegerry    Sorry,  I haven't heard from you, So you may not want my help at all, but I just started a new job.  I'll be working a ton of hours for awhile.  Won't be able to help.  Tim

@likklegerry   
sorry,  I just saw this.  PM me, I'll help you figure this out. 
Tim

Correction to my post deleted. 1/Lt = 1/L1+1/L2... So yeah, dcr is about 0.05 ohms or less. Initially thought it would be about 0.68 ohms, but that was incorrect.

Yes, thanks for the links, info and your input. To me, it looks like the wire gauge is 22 or 24. Doesn't appear to be 18 for sure, but hard to tell.

Lower than expected dcr for 0.22uH inductor; from what I can tell, a nominal dc resistance for that inductor is about 0.21 ohms.

Are you refer to the 0.22mH inductor across the tweeter?
https://ucarecdn.audiogon.com/a89e98dd-d4a0-4acf-9f74-934683ea9b70/-/autorotate/yes/
 
DCR varies with wire gauge and core type, for example, DCR of an 0.22mH 18AWG air core inductor is about 0.2Ω, DCR of an 1mH 18AWG "I" core inductor ( about 4.5 times higher inductance than 0.22mH ) is only 0.17Ω. You can see from the photo that it is an cored inductor, I won't be surprised its DCR will be 0.05Ω or less.
https://ucarecdn.audiogon.com/bfe5fcb3-3dd7-42ff-835d-9e69c47231fd/-/autorotate/yes/

Lower than expected dcr for 0.22uH inductor; from what I can tell, a nominal dc resistance for that inductor is about 0.21 ohms. Think that is one area that needs some additional testing.

I just recently learned that iron core inductors are suppose to be better than air core for the bass driver due to the lower dc resistance in many cases.

@fiesta75
If replace a cored inductor with air core, I think it is important to use the same inductance air core inductor with very close DCR to the cored inductor, it will be bigger, heavier and cost more.

I’m still learning...

I'm as well, learning is a lifelong process.

He wouldn’t even need to make a PCB, he can just use point to point wiring for those 2 components

Agree 100%

imhififan - I agree on both suggestions. I just recently learned that iron core inductors are suppose to be better than air core for the bass driver due to the lower dc resistance in many cases.

Yeah, they have lower DCR, but sometimes that DCR is quite useful as part of the baffle step compensation, and in even ordered parts of a high pass filter that DCR is again quite handy.  Still, if you want massive power handling, and a very low frequency cutoff, iron core is hard to beat.

Best,

E

imhififan - I agree on both suggestions. I just recently learned that iron core inductors are suppose to be better than air core for the bass driver due to the lower dc resistance in many cases. Tannoy  is one that uses iron core on some speakers, I'm still learning... He wouldn't even need to make a PCB, he can just use point to point wiring for those 2 components and that would also reduce the dcr.

Tell you what,you guys have put so much time and effort into this,this weekend i am going to clean everything up and start again,i will take variuos readings on crossovers,re-assemble the whole two speakers and do it all again and then i will come back with a list of readings,it seems thats all i can do,

Something to consider:

Put the LF xover ( the 3.5mH inductor and 51uF capacitor ) on a separate circuit board to eliminate shorts from HF/MF crossover components.
Better yet, upgrade to air core inductor!

https://images-na.ssl-images-amazon.com/images/I/71pf0GZOI1L._AC_SL1500_.jpg

@likkelgerry-

       "30 years of Hifi, i dont think one meal will cover that....you know how we get!!"

        Exactly why I'm single, again (well: one of a FEW reasons, anyway)!

where i have written"   speaker terms with everything connected" ive written Hi and low, which means mid/high and bass,on the speaker posts,just to clear that.
thanks guys

ok i have uploaded my original readings,via a picture.
later guys

thankyou for that,some thing seems a miss,i do read 0ohms,i also found my orignal written values also this morning when i first started investigating all this,
Tell you what,you guys have put so much time and effort into this,this weekend i am going to clean everything up and start again,i will take variuos readings on crossovers,re-assemble the whole two speakers and do it all again and then i will come back with a list of readings,it seems thats all i can do,i really appreciate all the help,i really do.
And thank you all again
Mk

If you measure the resistance across the loudspeaker posts which include connection to the bass driver (or full range) then you will measure some resistance that is greater than 0Ω which is made up of the crossover components and the voice coil resistance of the bass driver only. You are not measuring the impedance of the loudspeaker, in fact an impedance measurement doesn't mean anything unless you know the frequency you are measuring at.

In your configuration you should see open circuit for MF/HF and some resistance across LF. Which you do when the crossover is disconnected from the speaker terminals.
If I understand you correctly it is only when you put the loudspeaker back together that you read 0Ω across the MF/HF. If that is correct then you have a short which is upstream of the crossover i.e. the loudspeaker terminals, connecting wires etc.
If the MF/HF connectors really are a dead short then your amplifier would fail immediately... actually it should go into overcurrent protection but I digress.

Something doesn't add up.

1) You measure 0Ω across the MF/HF terminals of both speakers.

2) When you had everything disconnected you measured open circuit across IP+ & IP-. That is what you would expect.

Knowing that, it should be simple with the crossover disconnected to measure the resistance across the loudspeaker terminals to locate the short. If there's not one then the short was either at the point the wires connected to the crossover or items 1 & 2 listed above are incorrect.

The fact that both speakers measure 0Ω at the MF/HF terminals implies that you're not looking for a stray wire or small solder bridge but a mistake or failure on both speaker inputs. That's why something like connecting the amplifier outputs incorrectly seemed like a likely scenario... although I know you've ruled that out.

ps,just found this in an old book
7.1ohms LEFT MID/HIGH 8+6.4=4+3.2=7.2
6.8ohms LEFT Bass 6.8

7.0ohms RIGHT MID/HIGH 7.5+6.5=3.75+3.25 
6.8 ohms RIGHT Bass 6.8
i must have taken these measurements of the speakers a few years ago,which are different to the measurements that we have now,i know these are the measurements as i only own one pair of bi-wirable speakers

wow,such a lot of input,thx guys.ok
Fiesta 1st," Are you SURE that when you bi-amped the speakers after getting the amp back from servicing that you didn't forget to remove the second set of cables to the low and mid/hi inputs? "
the two amp to speakers where wired correctly,the cables are all marked up correctly left/right,plus minus, and they have different plug,banna and another type,so it impossible to mix them up,plus i dont ever use jumpers on the back of the speakers.
Sorry,not parts list available, he wouldn't give me one,i asked but got no reply on that score.he said it was getting too hot and fitted a fan after repair,which i wasnt keen on ,as i see that as covered up WHY it is getting too hot.
On doing re-work,all i have done is,removed the cables from the x-over and tested continuity from every component to the track on the PCB,every thing checked out,also i clean up the board with pcb cleaner,to remove flux stains.
change out from ,  4.2uf and the one you installed is 3.9uf,may not be correct,im still looking for the old caps,to verify the are the same type,like for like,as wilmslow may have updated that schem,as the speaker evolved with different drivers in it,as i have 100s and 100s of caps from different projects,im just struggling, at this moment to put my hands on them,
Rodman- the difference between using  one and two power amps,i heard my system using two and heard it using one,i dont want to back to one,tow sounds amazing,one sounds ok,im sure you know what i mean,ive been evolving this system for 30 years,i dont want to loose 10 of them,sorry.

"  Meanwhile: take the Wife OUT for some Meshana Skara or Mousaka and help her relax!    Top it off with some Marudnik (are wild berries in season over there?) and make her love you, again!"
30 years of Hifi,  i dont think one meal will cover that....you know how we get!!.but thx for the advise.

imahififan- no short,,the picture shows a little solder splash,where i DE soldered the other x-over cap to check it,but and in that picture the cap lead is not soldered down,but well spotted, that is studying these pics very closely thx.

So guys,it looks like we are running out of ideas,which makes me feel ,like it might be some thing else,as you guys would have picked up on it,

I know this may sound stupid,so when i test a speaker ,at the binding posts,disconnected,i cannot just put the mul/mtr in ohms and check to see what ohms the speaker is/are ??.as thats what ive done for years !!,im sure that when ,infact i know thats what i did when i found a a tweeter blown  and what i did when i re-capped the x-overs and when ever i test a speaker to see what ohms it is,totest its ok ??.

just a little note,when these amps have blown,they have made the same noise both times ,through the speakers,just like a little pop,then the amp goes into alarm,exactly the same sounds,just thought i would through that in there,
when ive tested these speaker in the past,the way i have expalained ,i have never had 0ohms for the mid/high ,im pretty sure of that,im just putting it out there,
Another thing ,because the amp is getting hot{but they do run hot [Arcam Alpha 10Ps} and they are 25 years old,do you think i should give them a re-cap?,will this possibly bring them back into spec and cool down a  little,.Anyway ill get back to my concreting.
cheers guys

imhififan - That is an excellent catch. I was beginning to think along with rodman, that maybe the problem was outside of the speaker crossovers. I think you may have nailed it. I suppose the single short could have caused both channels of the amp to have failed, or maybe the other board has similar issues? I have asked OP about a list of parts that were replaced when the amp was serviced, wonder if he has that info. What do you think about the lower than anticipated resistance measured across the 0.22mH inductor?

Please look at this photo:

https://ucarecdn.audiogon.com/32d4343f-f8e2-4de2-95f7-2e0766972c94/-/autorotate/yes/

If that is a short, for bi-amping, it will connect two amplifier output together through the 3.5mH inductor and the 3.3Ω resistor. There could be more similar problem spots on the PCB that we can’t see from those photos, that was the reason I suggest OP to clean up the PCB and reinstall components.

@likkelgerry-    I do not envy you being so far from someone versed in electronic repair.

       Here's hoping you are able to locate the issue and get it resolved, without having anything further go awry with your amp.

        Unless the bi-amp configuration made a MAJOR leap upward, regarding sound quality, to your ears; I'd button things back up and run with one!

         Meanwhile: take the Wife OUT for some Meshana Skara or Mousaka and help her relax!     Top it off with some Marudnik (are wild berries in season over there?) and make her love you, again!

                                


       

@fiesta75-     " I just don't want the OP to do anymore work on the boards before doing tests. It seems like he is doing rework in the middle of the tests and that could make some tests invalid. This could create more problems as I'm sure you know."

                              I get that and agree, fully!

       Still believing the problem to exist outside of the crossover components themselves: I'll stop flapping my fingertips!

     

imhififan - That was very helpful, thank you!

**likklegerry - Small difference between the original capacitor values and the ones you installed will not cause failures of the amplifiers. If anything, it would have a SLIGHT chance to damage the tweeter or midrange driver. Since it appears that the value of the original capacitor for the tweeter was 4.2uf and the one you installed is 3.9uf, that would very slightly raise the crossover frequency and absolutely NOT cause damage to the tweeters or amplifier. The caps you installed will definitely improve the sound, so please just leave them in.

Here are my posts from that day:
06-16-2021 5:40pmOkay, its been a rough couple days. I just got done drawing the schematic and looking at the words and measurements again. Just one note, do all measurement in the resistance mode, not in the diode mode as the diode mode really doesn't tell us anything. You don't need to disconnect one end of the resistors to check each resistor. So with no drivers attached, between the midrange terminals on the crossover board, you get close to 2.2 ohms, but it's not a dead short correct? For the tweeter terminals, you get close to 0 ohms, but not a dead short correct? At the mid/hi amp inputs, you get essentially OL after holding the probes on the terminals for few seconds, correct? What happens when you reverse the leads on the mid/hi amp terminals? Does the meter go to (-) xxx.x ohms then to (+) xxx.x ohms before going to OL? This is a dumb question, but just so I understand everything. When you use only one amplifier to power the speaker in the full range (bi-WIRE) mode, the (+) terminals of the inputs are connected together. And separately, the (-) terminals of the inputs are connected together, correct? The photos are gone, but don't think we need it again. From your DC voltage measurements at the amps, they look healthy. Please answer all of my questions in order, so we don't get confused, thanks.fiesta75404 posts06-16-2021 5:48pmWhich resistor, if it's STILL showing a dead short or 0.00 ohms? This is the one mentioned in post 6-16 @ 12:59amfiesta75404 posts06-16-2021 7:06pmCORRECTION, sorry. The last test on the mid/hi amp terminals on the crossover board; when I asked to to test and then reverse the meter leads and test again. The multimeter should be set on the "diode" test mode, not ohms. The readout should display some voltage then go to OL. When you immediately reverse the leads, the display should read -x.xxx volts, then change to +x.xxx volts before going to OL. Hope your meter has a diode test function, but it's not absolutely necessary. This test just shows that the caps are charging in both directions.
I still can't explain why the system worked with one amp when the mid/high amp was in repair... This is troubling.

rodman - I appreciate your comments. I just don't want the OP to do anymore work on the boards before doing tests. It seems like he is doing rework in the middle of the tests and that could make some tests invalid. This could create more problems as I'm sure you know. The only test I want from him before finalizing everything is the dc resistance across the tweeter terminals of the board, because his last info on that makes me think the resistance he measured was below what I expected from a 0.22 mH inductor. All help is welcome.

@fiesta75-   I don't see a post, from you, dated 6-16 @ 7:06pm, at all.

     Nor anything vaguely explaining why nonpolarized caps behave like they do and are supposed to, when presented with DC, which was my ONLY intent and, as I've mentioned twice now, "just FYI/fun facts"..

      I did see something about connecting DC, and what readings may occur, at the terminals, from you.

      Given his question, regarding his DMM readings, when changing the polarity:   "Diode test on mid/high -OL
when reversed is flashes 2.2xx,then goes to OL
every time i reverse leads it flashes something {2.2xx}not sure its voltage,it doesnt tell me that"      to which I replied,  wasn't even posted until 6-22 @5:10am, I have to ask:

                                                     Are you a prophet?

rodman - Just FYI, I did explain that the diode function test was to verify the charging and discharging of the capacitors. This was in my post of 6-16 @ 7:06pm. His answer showed there was no longer a short at the inputs of the mid/hi amp connections.

I'm curious, do you have a list of parts that were replaced when the amp was serviced? A list from the first repair and one from the second repair might shed some light on a potential cause for the failures.

I don't believe there is a problem that exists on the crossover any longer. Let's just do a few more tests. 

The fact that the speakers and amps worked of a couple or more hours is a hint that the problem may not be in the crossover. Are you SURE that when you bi-amped the speakers after getting the amp back from servicing that you didn't forget to remove the second set of cables to the low and mid/hi inputs? If the amps were connected in the outputs, even just one wire like the negative or positive between amps, that could have caused the amplifier failure.

I didn't know you were in Bulgaria, that explains the delays in communication. I think a few more tests are the only thing that is required to conclude that the issue is solved. I'm still willing to try.

The testing of the mid/hi input terminals showed the caps at that end of the circuit were charging and discharging. No shorts or problems were noted in that particular test.

Hi rodman,whn everything is connected in a  one or two amp system is in use ,everything sounds great,the sound is amazing, slightly better with two power amps {obviously},but nothing is a miss,its just that it keeps blowing one amp,the one driving the mid/highs,and that is the only problem,i just cannot find out why,but every time it blows an amp,it cost me a fortune to send to Sofia about 200 miles from where i live in Bulgaria,as its the only tech i can find in the country,postage alone is £50plus the repair another £100 plus.


gregm3,iits not esay in bulgaria to find a electronic HIFI tech,,to find any tech is a job in its self,a good one is like rocking horse ..

Cheers guys Mk

@likkelgerry-  Apparently: I wasn’t clear enough, when answering the question you posted (on 6/22).

     NOTHING in my answer has ANYTHING TO DO, with the problem you’ve experienced. (specifically why I stated, "just FYI/fun facts")

     Any PROPERLY FUNCTIONING nonpolar/bipolar capacitor, will act the same way, when presented with DC.

     Once they charge in the direction of the DC current’s flow, they BLOCK any further DC, which (when used as coupling caps) is their intended purpose.

     What I suggested would not damage ANYTHING bigger than the typical tweeter, OR: I wouldn’t have suggested such.

                          Obviously: my use of the word, "POP" triggered something.

                             btw: I still stand by my first post to this thread (on 6/10).

     IF your crossovers were truly functioning properly (everything sounded as it should), when correctly connected to ONE amp, all of those crossovers’ internal components were fine, to start with.

                                              "...my wife is going crazy."

                                                             I’ll bet!

Sorry to state the obvious but, why not just take the xovers along with the schematic to your local eletrician who will solve the issue in a jiffy for a few quid -- if that:)
There's a short somewhere in the tweet xover and that's tricky to identify from afar It could be a component failure, a wrong connection, etc)!Good luck

pps,just to add to my explanation ,i feel that there might be a value issue here,what do you guys think,ive possibly fitted the wrong value caps{i dont think i have,as i would have compared them before fitting}but they are definitely different type of caps,ill dig the old ones out and put the old type and what i replaced then with on here later,but today i have to do some concreting, my wife is going crazy.
thanks again guys
M

pps,does any know how to remove hot glue ??,the easy way

ps,thankyou thomas for the explanation and time,you know who you are.

thank you all guys i am so honoured for all your help,but i think i am going to go for the simple fact,that,i think all these problems may have started when i changed out all the caps,on the cross over,im going to find the old ones which i removed,check there values again ,against the schematic i have uploaded ,and maybe ask you guys if they are compatible/same,like for like to do the job,i received a private email,that explained that they maybe different,although i did get them from Wilmslow audio and stated they where for an upgrade for my speakers,but it just might be worth trying the obvious stuff first,as soon after the change out,is when this problem started,2 years ago.still dont understand why it works with only one power only though,and not two.weird.
Just to answer your last question though.

pragmasi,the the binding posts holder is plastic,no short there.
i connect the speakers via two cables{pairs]to a four post bi-wire termial posts,in one amp mode,i use the same cables and posts ,but use the two sets of speaker post on the back of the amp.

Hi fiesta the blue circled cap is 6.8uf 250v cap,which is the one that looked like it had a short,but after desoldering it from the board ,it tested on,no continuity and good cap testing values,so was red herring,someone said it was because it was in parallel with other parts reason for show a short
fiesta-
" In one photo I can read 3.9uf/250V. When you drew and label the components on the circuit board the 4.2uf should have been 3.9?"
I didnt draw the x-over i received it from wilmslow audio and posted it here,

maybe i have the wrong caps,i will dig out the old ones and check/compare.

hififan,i checked out the link,had a look at the schem,that one is similar,but are they not all individual to every speaker?,im not sure.

rodman,i dont really want to go down that route of testing with expendable drivers and amps,its exspensive, when things go pop,but thanks,plus the speakers work,but after a few hours the amps goes pop,so i dont think its an obvious fault,but possibly a high draw problem,putting strain on the amp driving the mid/high drivers,but thanks for the input.infact thank you all for your imput.
im going to check out the cap values and tyes again ,against that schematic.

@likklegerry-    re: Your first post on this page:

 "Diode test on mid/high -OL
when reversed is flashes 2.2xx,then goes to OL
every time i reverse leads it flashes something {2.2xx}not sure its voltage,it doesnt tell me that"

      Only here to address that question, as I didn't notice any other answer (just FYI/fun facts).

       A non/bipolar cap, when presented with DC, will charge in one direction.  Reverse the polarity and it will discharge and charge in the opposite direction.

            That's what your DMM is reading, for that brief instant.

       As an experiment: Connect a non/bipolar cap in series with a speaker.    Don't use a tweeter, unless it's expendable.

        Touch a 9V battery's + post to the open lead of the cap and -, to the open speaker terminal.    Hold it there, for a few seconds.     Longer: the greater the cap's values

         Reverse those connections and you'll hear a *POP, every time.

                                        *The cap, discharging

I don’t know it’s can be of any help, you can find the xover schematic here:

https://ucarecdn.audiogon.com/a89e98dd-d4a0-4acf-9f74-934683ea9b70/-/autorotate/yes/

In one photo I can read 3.9uf/250V. When you drew and label the components on the circuit board the 4.2uf should have been 3.9?

Stop, I would not strip any parts off either board. The data, answers to my questions, looked promising. You’ve already done a lot of visual inspection and testing. The most recent pictures, the cap with the blue circle around it, what is that? Suspect bad part? What is the printed value of the cap including the voltage rating?

ps was that pragmasi or eric which posted the equation post ?

That was me re-posting Eric's advice to point out how it wasn't very helpful.

1) Original test with everything assembled showed 0Ω resistance across the MF/HF +/- terminals on the back of the speaker.
2) Those terminals connect directly to IP+ and IP- on the crossover PCB.
3) With the crossover disconnected the DC resistance between IP+ and IP- was open circuit.
If points 1-3 are correct and you’ve put it back together and measured 0Ω across the loudspeaker terminals then there’s a short somewhere between the terminals and where the wires connect to IP+ and IP-.

totally correct

Okay, that should narrow it down a bit and you can stop worrying about the crossover. If you only get the short when the loudspeaker is reassembled then you're looking for something between the crossover PCB and the loudspeaker inputs. If you disconnect the crossover you should be able to track it down... what are the binding posts on the loudspeaker mounted to, plastic or could it be anodized aluminium?

i had a good play about with them both today,x-overs,couldnt find a problem ,maybe i should just strip them down,or one,check all parts then reasemble,not sure how to test the inductors though,as i can see i dont know enough, I can test parts but all this equations for test with a multi meter only,idont evem know what mH is !!??.Didnt think this would be that hard, obviously im wrong again.
cheers guys for all your help