Home |
Search |
Today's Posts |
#1
Posted to rec.audio.high-end
|
|||
|
|||
Tannoy Monitor Gold Dual concentrics
Hi,
I've inherited my father's old 10" Tannoys (in the Tannoy vented enclosures). They still sound good, but I've noticed that there is an imbalance between the two speakers. One sounds a bit louder, (it could be just a difference in the treble range) and swapping the source leads, or swapping the speaker leads makes no difference. The effect is confirmed with mono source - the sound does not seem to come from the midpoint of the speakers. I don't have access to proper testing gear, but I do have a multimeter and a basic understanding of electronics. I'm wondering what sort of testing sequence I can follow. I have checked that the two voice coils on the lower output unit are intact, with DC resistances of about 8.2 and 4.4 ohms on the tweeter and bass respectively, so it isn't an obvious driver issue (I would have heard the loss of sound quality in any case). Now I'm thinking about the crossover unit. Can I perform simple ohmmeter tests on the crossover, or will any deterioration only show up in AC? I guess the next question is should I just go ahead and replace some crossover components (capacitors) since these are now about 40 year old. Thanks for any suggestions. Gib |
#2
Posted to rec.audio.high-end
|
|||
|
|||
Tannoy Monitor Gold Dual concentrics
"Gib" wrote in message
... Hi, I've inherited my father's old 10" Tannoys (in the Tannoy vented enclosures). They still sound good, but I've noticed that there is an imbalance between the two speakers. One sounds a bit louder, (it could be just a difference in the treble range) and swapping the source leads, or swapping the speaker leads makes no difference. The effect is confirmed with mono source - the sound does not seem to come from the midpoint of the speakers. I don't have access to proper testing gear, but I do have a multimeter and a basic understanding of electronics. I'm wondering what sort of testing sequence I can follow. I have checked that the two voice coils on the lower output unit are intact, with DC resistances of about 8.2 and 4.4 ohms on the tweeter and bass respectively, so it isn't an obvious driver issue (I would have heard the loss of sound quality in any case). Now I'm thinking about the crossover unit. Can I perform simple ohmmeter tests on the crossover, or will any deterioration only show up in AC? I guess the next question is should I just go ahead and replace some crossover components (capacitors) since these are now about 40 year old. Thanks for any suggestions. Gib I'd leave the electronics alone for now, and buy either a test CD (from Stereophile or Radio Shack) or test LP and use your ears and the test disk to record/track frequency response (they all have such a test, intended for just such purpose, on them). My suspicion is that you will find a high frequency rolloff in one, most likely due to a "dead" horn tweeter (which will be in the middle of the speaker). Once you have detemined if this is the case or not, you can figure out what to do next. |
#3
Posted to rec.audio.high-end
|
|||
|
|||
Tannoy Monitor Gold Dual concentrics
Hi Harry,
Meanwhile I had a look at the crossover box, and noticed some deformation of the plastic consistent with heating. Upon opening it up I found that the two resistors on the edge of the PCB (5 and 10 ohms) have been very hot. Right next to these resistors on the other side is a capacitor, 3.3 uF from the Tannoy circuit diagram. Interestingly the crossover shown on Troels Gravesen's site www.troelsgravesen.dk/Tannoy_IIILZ.htm has 3.3 uF electrolytics, but these capacitors in my crossover are not electrolytic. In any case the one next to the resistors shows signs of having been exposed to high temperatures, and it could well have suffered. By the way, I'm confident that the tweeter is not dead - the speaker sounds reasonable, not totally deficient in treble. So I will replace the 3.3 uF capacitor, and while I'm at it I'm inclined to replace the 25 uF and 8 uF electrolytics. I have to decide whether to stick with electrolytics or to go with a more expensive option (if one is available). The test CD or LP, by the way, is an excellent idea. Cheers Gib |
#4
Posted to rec.audio.high-end
|
|||
|
|||
Tannoy Monitor Gold Dual concentrics
You can replace all of those capacitors with non-electrolytics, these are
not large values - but the replacements will be physically larger. If you select 50 volt capacitors you will have plenty of voltage margin. There are claims that different dielectric materials affect sound quality - I don't know how this plays out in crossover networks though. Capacitors are cheap - so it may be worth some experimenting - try polypropelene, mylar, maybe a oil type motor run capacitor - see if you hear a difference, and use what you like "Gib" wrote in message ... Hi Harry, Meanwhile I had a look at the crossover box, and noticed some deformation of the plastic consistent with heating. Upon opening it up I found that the two resistors on the edge of the PCB (5 and 10 ohms) have been very hot. Right next to these resistors on the other side is a capacitor, 3.3 uF from the Tannoy circuit diagram. Interestingly the crossover shown on Troels Gravesen's site www.troelsgravesen.dk/Tannoy_IIILZ.htm has 3.3 uF electrolytics, but these capacitors in my crossover are not electrolytic. In any case the one next to the resistors shows signs of having been exposed to high temperatures, and it could well have suffered. By the way, I'm confident that the tweeter is not dead - the speaker sounds reasonable, not totally deficient in treble. So I will replace the 3.3 uF capacitor, and while I'm at it I'm inclined to replace the 25 uF and 8 uF electrolytics. I have to decide whether to stick with electrolytics or to go with a more expensive option (if one is available). The test CD or LP, by the way, is an excellent idea. Cheers Gib |
#5
Posted to rec.audio.high-end
|
|||
|
|||
Tannoy Monitor Gold Dual concentrics
Thanks Bill. In fact the range of capacitors available here (NZ) is
very limited, and they're not cheap. The best source here in Auckland doesn't have 25 uF @50v, the closest is 2*10 uF + 4.7 uF, all at 160v (i.e. big), and I have to buy a 5-pack of each size. I was able to get 3.3 and 8 (actually 8.2) in non-electrolytic, some sort of poly. My interim plan is to replace the 25 with an electrolytic, and order a non-electrolytic replacement from overseas if necessary. Is there any advantage to using a bipolar electrolytic? Cheers Gib On Oct 12, 4:12=A0am, "Bill Noble" wrote: You can replace all of those capacitors with non-electrolytics, these are not large values - but the replacements will be physically larger. =A0If = you select 50 volt capacitors you will have plenty of voltage margin. =A0Ther= e are claims that different dielectric materials affect sound quality - I don't know how this plays out in crossover networks though. =A0Capacitors are cheap - so it may be worth some experimenting - try polypropelene, mylar, maybe a oil type motor run capacitor - see if you hear a difference, and = use what you like "Gib" wrote in message ... Hi Harry, Meanwhile I had a look at the crossover box, and noticed some deformation of the plastic consistent with heating. =A0Upon opening it up I found that the two resistors on the edge of the PCB (5 and 10 ohms) have been very hot. =A0Right next to these resistors on the other side is a capacitor, 3.3 uF from the Tannoy circuit diagram. Interestingly the crossover shown on Troels Gravesen's site www.troelsgravesen.dk/Tannoy_IIILZ.htmhas 3.3 uF electrolytics, but these capacitors in my crossover are not electrolytic. =A0In any case the one next to the resistors shows signs of having been exposed to high temperatures, and it could well have suffered. =A0By the way, I'm confident that the tweeter is not dead - the speaker sounds reasonable, not totally deficient in treble. =A0So I will replace the 3.3 uF capacitor, and while I'm at it I'm inclined to replace the 25 uF and 8 uF electrolytics. =A0I have to decide whether to stick with electrolytics or to go with a more expensive option (if one is available). The test CD or LP, by the way, is an excellent idea. Cheers Gib |
#6
Posted to rec.audio.high-end
|
|||
|
|||
Tannoy Monitor Gold Dual concentrics
"Gib" wrote in message
... Hi Harry, Meanwhile I had a look at the crossover box, and noticed some deformation of the plastic consistent with heating. Upon opening it up I found that the two resistors on the edge of the PCB (5 and 10 ohms) have been very hot. Right next to these resistors on the other side is a capacitor, 3.3 uF from the Tannoy circuit diagram. Interestingly the crossover shown on Troels Gravesen's site www.troelsgravesen.dk/Tannoy_IIILZ.htm has 3.3 uF electrolytics, but these capacitors in my crossover are not electrolytic. In any case the one next to the resistors shows signs of having been exposed to high temperatures, and it could well have suffered. By the way, I'm confident that the tweeter is not dead - the speaker sounds reasonable, not totally deficient in treble. So I will replace the 3.3 uF capacitor, and while I'm at it I'm inclined to replace the 25 uF and 8 uF electrolytics. I have to decide whether to stick with electrolytics or to go with a more expensive option (if one is available). The test CD or LP, by the way, is an excellent idea. Cheers Gib Sounds like you are right on it. Do those things, and if it still sounds funny, go to the test disk. |
#7
Posted to rec.audio.high-end
|
|||
|
|||
Tannoy Monitor Gold Dual concentrics
On Oct 11, 9:35=A0pm, Gib wrote:
Thanks Bill. =A0In fact the range of capacitors available here (NZ) is very limited, and they're not cheap. =A0The best source here in Auckland doesn't have 25 uF @50v, the closest is 2*10 uF + 4.7 uF, all at 160v (i.e. big), and I have to buy a 5-pack of each size. =A0I was able to get 3.3 and 8 (actually 8.2) in non-electrolytic, some sort of poly. My interim plan is to replace the 25 with an electrolytic, and order a non-electrolytic replacement from overseas if necessary. =A0Is there any advantage to using a bipolar electrolytic? Cheers Gib On Oct 12, 4:12=3DA0am, "Bill Noble" wrote: You can replace all of those capacitors with non-electrolytics, these a= re not large values - but the replacements will be physically larger. =3DA= 0If =3D you select 50 volt capacitors you will have plenty of voltage margin. =3DA0= Ther=3D e are claims that different dielectric materials affect sound quality - I don= 't know how this plays out in crossover networks though. =3DA0Capacitors a= re cheap - so it may be worth some experimenting - try polypropelene, myla= r, maybe a oil type motor run capacitor - see if you hear a difference, an= d =3D use what you like "Gib" wrote in message ... Hi Harry, Meanwhile I had a look at the crossover box, and noticed some deformation of the plastic consistent with heating. =3DA0Upon opening= it up I found that the two resistors on the edge of the PCB (5 and 10 ohms) have been very hot. =3DA0Right next to these resistors on the o= ther side is a capacitor, 3.3 uF from the Tannoy circuit diagram. Interestingly the crossover shown on Troels Gravesen's site www.troelsgravesen.dk/Tannoy_IIILZ.htmhas3.3 uF electrolytics, but these capacitors in my crossover are not electrolytic. =3DA0In any ca= se the one next to the resistors shows signs of having been exposed to high temperatures, and it could well have suffered. =3DA0By the way, = I'm confident that the tweeter is not dead - the speaker sounds reasonable, not totally deficient in treble. =3DA0So I will replace t= he 3.3 uF capacitor, and while I'm at it I'm inclined to replace the 25 uF and 8 uF electrolytics. =3DA0I have to decide whether to stick wit= h electrolytics or to go with a more expensive option (if one is available). The test CD or LP, by the way, is an excellent idea. Cheers Gib A polarized cap will NOT work. They must be bipolar. You can also wire polarized caps back to back to form one. I would suggest getting a cheap cap tester and measure all the caps, and resistors. Substitution other caps for electrolytics can cause problems. the thing was designed using electrolytics, so changing values may be required to get the orginal sound. This should be in rec.audio.tech. greg |
#8
Posted to rec.audio.high-end
|
|||
|
|||
Tannoy Monitor Gold Dual concentrics
On Oct 10, 7:32=A0pm, Gib wrote:
Hi, I've inherited my father's old 10" Tannoys (in the Tannoy vented enclosures). =A0They still sound good, but I've noticed that there is an imbalance between the two speakers. =A0One sounds a bit louder, (it could be just a difference in the treble range) and swapping the source leads, or swapping the speaker leads makes no difference. =A0The effect is confirmed with mono source - the sound does not seem to come from the midpoint of the speakers. =A0I don't have access to proper testing gear, but I do have a multimeter and a basic understanding of electronics. I'm wondering what sort of testing sequence I can follow. =A0I have checked that the two voice coils on the lower output unit are intact, with DC resistances of about 8.2 and 4.4 ohms on the tweeter and bass respectively, so it isn't an obvious driver issue (I would have heard the loss of sound quality in any case). =A0Now I'm thinking about the crossover unit. =A0Can I perform simple ohmmeter tests on the crossover, or will any deterioration only show up in AC? =A0I guess the next question is should I just go ahead and replace some crossover components (capacitors) since these are now about 40 year old. Thanks for any suggestions. Gib Sort of a distillation of other advice given he a) Rebuild your crossovers. Replace _all_ the resistors and _all_ the capacitors. The caps should be non-polarized, and if you use electrolytics spend the few extra bucks to get high-temperature units at 50V or better. Use good resistors as well, rated at-or-better than what you take out for wattage. If there are controls on the crossovers, clean them thoroughly. Given the age of these units, all of the above should be done as a matter of course and won't cost you very much either. b) Only then will the test disc do you much good. With what is in there now your perceived defect could be about anything up to and including a bad driver - but not for sure. c) Heed the advice on polarized caps. You can put caps back-to-back (tied on the negative side, positive side out), but to get 25uF, you will have to put two 50uF caps back-to-back (in reality given the tolerances for electrolytics, 47uF (standard size) caps will do fine. d) The attached website might help: http://www.mouser.com/contact-australia= / Peter Wieck Melrose Park, PA |
Reply |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Tannoy Monitor Gold intermittent socket | Tech | |||
FA : Tannoy system DMT 15 15" Tannoy dual Concentric | Pro Audio | |||
FA : Tannoy system DMT 15 15" Tannoy dual Concentric | Marketplace | |||
WTB: SINGLE TANNOY MONITOR GOLD IN ANY CAB | Marketplace | |||
monitor roundup: Tannoy Reveal, Tannoy PBM 6.5 II, Event 20/20 v1 | Pro Audio |