Quantum Jr. Dome midrange
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loquatious
village elder
there are threads in this forum outlining how to fix these. if it is beyond your skill set, i'd think you can find a correct working original for much less than $115. the original 1.5" dome mid was made by braun and had a part number 902-0206 (the monitor jr. tech sheet has the wrong part #. it shows 902-0260, another HK mistake).
speaking of mistakes, the pair of "quantum" midranges on ebay right now are not correct, they are audex units someone used as replacements (the seller hasn't figured it out. he's selling them as originals).
the 1.5" braun dome midrange was used in infinity's quantum series as well as the monitor series.
http://www.audiokarma.org/forums/showthread.php?t=398687
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speaking of mistakes, the pair of "quantum" midranges on ebay right now are not correct, they are audex units someone used as replacements (the seller hasn't figured it out. he's selling them as originals).
the 1.5" braun dome midrange was used in infinity's quantum series as well as the monitor series.
http://www.audiokarma.org/forums/showthread.php?t=398687
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Coastsider
Curmudgeon
One of the anomalies relative to the Braun dome midrange drivers used in the mid to late 70's Monitors as well as the later Quantums is that the Monitor IIa used a slightly larger dome midrange driver than was used in the Monitor Jr. as well as in all of the Quantums as far as I can tell from available photographs. I don't know why this is the case but below are photos I just took minutes ago of the midrange drivers in one each of the pairs of Monitor IIa's and Monitor Jr's that are currently in service in my music room. The recently restored second pair of Monitor Jr's I have in service in my office have the same smaller driver.
The Monitor IIa midrange dome:
And the Monitor Jr midrange dome:
I think this was discussed in another thread some time ago but I am unable to find it.
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loquatious
village elder
the funny thing is, the monitor IIa, the monitor jr., and the quantum tech sheets all list the mid as a 1.5" dome. is it just the mounting flange that varies in size, or the dome itself?
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Coastsider
Curmudgeon
Weird, huh?
I know - weird, huh? The mounting flanges around the IIa dome itself do seem larger with a thicker surround but the domes also seem larger as indicated in the photos but maybe it's an optical illusion. In any event it is a different driver, the information provided on the tech sheets notwithstanding. Even though I did not make a conscious effort, the photos are almost to the same scale.
I bought these Monitor IIa's new in 1976 and both the dome mids and dome tweeters are absolutely the original drivers. Maybe some other Monitor IIa owners can check their dome mids against my photos and chime in.
I know - weird, huh? The mounting flanges around the IIa dome itself do seem larger with a thicker surround but the domes also seem larger as indicated in the photos but maybe it's an optical illusion. In any event it is a different driver, the information provided on the tech sheets notwithstanding. Even though I did not make a conscious effort, the photos are almost to the same scale.
I bought these Monitor IIa's new in 1976 and both the dome mids and dome tweeters are absolutely the original drivers. Maybe some other Monitor IIa owners can check their dome mids against my photos and chime in.
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loquatious
village elder
my monitor IIa mids are like the 1st picture. here are the measurements i get:
the mounting plate is 5 1/8" square. the inner screws are spaced 2 3/8" apart. overall width of dome (including surround roll) is 2 3/8", and just the dome itself measures 1 3/4".
i don't know where they get the 1.5" (3.8cm) measurement on the tech sheets. i think HK just got it wrong again. and a size difference also brings the part numbers into question.
the drawing of the mid on the monitor IIa tech sheet is an accurate depiction of the driver. this seems true on the tech sheets for the numbered quantum's as well, (but not so for the quantum jr.).
i notice the quantum mids are slightly different in the drawings than their monitor IIa counterparts, and are labled 902-0206. the monitor IIa drawing has no part number for the mid, but says to substitute 902-0206.
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the mounting plate is 5 1/8" square. the inner screws are spaced 2 3/8" apart. overall width of dome (including surround roll) is 2 3/8", and just the dome itself measures 1 3/4".
i don't know where they get the 1.5" (3.8cm) measurement on the tech sheets. i think HK just got it wrong again. and a size difference also brings the part numbers into question.
the drawing of the mid on the monitor IIa tech sheet is an accurate depiction of the driver. this seems true on the tech sheets for the numbered quantum's as well, (but not so for the quantum jr.).
i notice the quantum mids are slightly different in the drawings than their monitor IIa counterparts, and are labled 902-0206. the monitor IIa drawing has no part number for the mid, but says to substitute 902-0206.
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Coastsider
Curmudgeon
I just made a huge mess of my spares closet digging out the box containing a pair of Monitor IIa dome mid-range spares, one of which has a broken tinsel lead and the other of which is fine. They are identical to the pair in my IIa's and I can only guess that I got them in one of the other two pair of IIa's that I acquired over the years for spares in which some of the drivers were either missing or not working. Those along with two or three pair of empty WTLC cabinets are stored in a closet off of my music room that is relatively inaccessible.
I guess since these Monitor IIa mids are apparently pretty rare I should see about getting the broken one repaired.
EDIT: Upon closer inspection of the damaged dome mid it would appear that at some point in time I had attempted to repair it and was unsuccessful in doing so.
I guess since these Monitor IIa mids are apparently pretty rare I should see about getting the broken one repaired.
EDIT: Upon closer inspection of the damaged dome mid it would appear that at some point in time I had attempted to repair it and was unsuccessful in doing so.
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loquatious
village elder
you are wrong about this. while the tweeters in the monitor IIa were made by peerless, the mids were made by braun. peerless never made drivers with the tinsel wires protruding out into space like braun did. this is a braun design flaw that was a recurring theme with their drivers. do a google image search and you won't ever find a peerless driver with it's tinsels hanging out in the breeze. braun did this over and over.
look at pictures of the part numbers you mention. neither is the mid we are discussing.
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Coastsider
Curmudgeon
The only markings on the back of the spares I have are "Made in Germany" and "44-6", both embossed in one corner of the frame, and the letters A e V inscribed in another.
"8Ω" is also stamped on the back of the magnet in white ink which is something Peerless used to do on the cones of some of their drivers. I'm not taking sides, just stating facts.
Maybe I'll give Miller Sound a jingle to see what they can do assuming my repair efforts didn't mess up the non-working driver beyond repair.
"8Ω" is also stamped on the back of the magnet in white ink which is something Peerless used to do on the cones of some of their drivers. I'm not taking sides, just stating facts.
Maybe I'll give Miller Sound a jingle to see what they can do assuming my repair efforts didn't mess up the non-working driver beyond repair.
loquatious
village elder
this has all been discussed and documented before, but to rehash…
braun didn't stamp their logo or part numbers on the magnets. they used a sticker. infinity took those stickers off, and they assigned their own part numbers for replacement purposes. ADS also used braun mids from this series. they didn't take the stickers off.
.http://www.canuckaudiomart.com/deta...ers2also-used-in-ads-speakers/images/1017629/
long ago, parts express bought out the inventory of new old stock braun mids and offered them at a discount price under stipulation the braun sticker was removed. to sell at their price point they could only say they were made in germany. they sold out of these mids years ago.
http://www.parts-express.com/treated-textile-1-1-2-soft-dome-midrange--279-104
braun was made in germany, peerless in denmark. sticker or no, these are german drivers.
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braun didn't stamp their logo or part numbers on the magnets. they used a sticker. infinity took those stickers off, and they assigned their own part numbers for replacement purposes. ADS also used braun mids from this series. they didn't take the stickers off.
.http://www.canuckaudiomart.com/deta...ers2also-used-in-ads-speakers/images/1017629/
long ago, parts express bought out the inventory of new old stock braun mids and offered them at a discount price under stipulation the braun sticker was removed. to sell at their price point they could only say they were made in germany. they sold out of these mids years ago.
http://www.parts-express.com/treated-textile-1-1-2-soft-dome-midrange--279-104
braun was made in germany, peerless in denmark. sticker or no, these are german drivers.
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Coastsider
Curmudgeon
Correction
The embossing actually says "Made in W. Germany" which makes more sense given the time frame.
Attached are the photos of the non-working spare that I just sent to Millersound.
Besides the open VC which may or may not be just the broken tinsel lead, the negative terminal is also broken off. It may just be a goner.
The embossing actually says "Made in W. Germany" which makes more sense given the time frame.
Attached are the photos of the non-working spare that I just sent to Millersound.
Besides the open VC which may or may not be just the broken tinsel lead, the negative terminal is also broken off. It may just be a goner.
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Coastsider
Curmudgeon
After doing a bit of highjacking (just a little) I'm going to swing this thread back to the original question posed by the OP.
As suggested by Bkphoto I contacted Millersound regarding the repair of my Monitor IIa Braun dome midrange (I have to side with loquatious relative to Infinity's source for these drivers) and got a pretty immediate reply as to the charges involved. I don't want to bend any AK rules but will just say that they are less than those services available on ebay and will send you a PM with the details.
Even though your Quantum driver is not the same as the spare I have for my Monitor IIa which I will probably send in for repair, it seems unlikely that the charges involved would be any different and so unless you can source an exact original replacement on ebay - there appear to be none available currently - I would suggest that repair is a viable alternative to using a non-original replacement.
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