Monitor IIa, ohm rating??
- Thread starter sansuigold99
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Coastsider
Curmudgeon
Remember that the Walsh is a unique super tweeter that radiates frequencies above 10KHz in a 360 degree pattern. What you've got essentially without working Walsh's are Monitor Jr.'s in a larger cabinet. The Monitor Jr. is rated 32Hz-22KHz with the dome tweeter handling everything above 5KHz just as it does in the Monitor IIa and it is a damn fine speaker so my suggestion would be to just leave your IIa's as is until you can source a pair of working Walsh's instead of trying to emulate the effect of the Walsh's with EMIT's because they just won't provide what loquatious refers to as the "sparkle" and "spaciousness" and what I like to call "shimmer" that the Walsh's add to the mix. And don't get me wrong - I have nothing against EMIT's and in fact have four different pair of Infinity's equipped with them and love how they sound. I just don't think they are appropriate for the purpose you suggest.
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loquatious
village elder
i'd be remiss if i didn't chime in and suggest that an emit in a IIa (while an interesting idea) would open a can of worms that may never yield satisfactory results, and may prove to be more trouble than its worth. deviations from stock undermine resale value as well.
a few things to consider:
as coastsider said, the walsh is a super tweeter (you have a dome tweeter) and gives 360º dispersion. to replace the walsh with another super tweeter, you need to source a semit (super emit) which are as rare, or rarer, than walshes and consequently more expensive. standard emits, and emit-r's are tweeters and cover a broader frequency range than the walsh.
the design of the original (ribbon-type) emit allowed for very narrow (beamy) dispersion: 30º horizontal X 18º vertical (some, used in line arrays, had only 7º vertical). the later (leaf-type) emit-r offered 30º X 30º dispersion. neither is suitable to be mounted facing up (you'd never be in the "sweet spot"), so you could not use the walsh mounting hole. you could eliminate the walsh altogether and seal the hole, then swap an emit for the dome tweeter, but then, you are changing from a 4-way to a 3-way system.
it only gets more complicated:
there were a lot of variations of emits, most look the same, but the spec's vary greatly. most emits were used in speakers rated at 6 or 4 ohms. semits used only in the real low-impedance amp-killers. mating one not designed for an 8 ohm speaker (like the IIa) could prove problematic. you'd need to redesign the crossover to accommodate the design change. mismatched components, impedance, changing the crossover points, and adding a protection circuit for the emit would all have to be addressed.
then there is a question of power. the emits were found in power-hungry speakers, and like a diet of 120-150 watts to come alive (in fact can be damaged if they don't get enough). the stock monitor IIa's are more than happy with 70 watts.
you've been living with SM150's which, frankly, are considered bottom-of-the-barrel infinitys. the stock monitor IIa's are a big step up from the SM line. personally, i think they deserve to be restored. do that and i think you'll be happy. if, once you've restored them, you find you want something else, sell them. if you don't want to restore them, i'd hope you'd pass them on to someone who will.
if you really want infinitys with emits, buy some. there are lots of them to choose from on the market all the time. they have matched components, and they were designed by people who knew what they were doing (until about 1993). there are some emit-equipped sleepers out there still to be had at bargain prices, but be aware that as you go up the infinity food chain it only gets more expensive. not only the speakers, but what it takes to drive them.
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a few things to consider:
as coastsider said, the walsh is a super tweeter (you have a dome tweeter) and gives 360º dispersion. to replace the walsh with another super tweeter, you need to source a semit (super emit) which are as rare, or rarer, than walshes and consequently more expensive. standard emits, and emit-r's are tweeters and cover a broader frequency range than the walsh.
the design of the original (ribbon-type) emit allowed for very narrow (beamy) dispersion: 30º horizontal X 18º vertical (some, used in line arrays, had only 7º vertical). the later (leaf-type) emit-r offered 30º X 30º dispersion. neither is suitable to be mounted facing up (you'd never be in the "sweet spot"), so you could not use the walsh mounting hole. you could eliminate the walsh altogether and seal the hole, then swap an emit for the dome tweeter, but then, you are changing from a 4-way to a 3-way system.
it only gets more complicated:
there were a lot of variations of emits, most look the same, but the spec's vary greatly. most emits were used in speakers rated at 6 or 4 ohms. semits used only in the real low-impedance amp-killers. mating one not designed for an 8 ohm speaker (like the IIa) could prove problematic. you'd need to redesign the crossover to accommodate the design change. mismatched components, impedance, changing the crossover points, and adding a protection circuit for the emit would all have to be addressed.
then there is a question of power. the emits were found in power-hungry speakers, and like a diet of 120-150 watts to come alive (in fact can be damaged if they don't get enough). the stock monitor IIa's are more than happy with 70 watts.
you've been living with SM150's which, frankly, are considered bottom-of-the-barrel infinitys. the stock monitor IIa's are a big step up from the SM line. personally, i think they deserve to be restored. do that and i think you'll be happy. if, once you've restored them, you find you want something else, sell them. if you don't want to restore them, i'd hope you'd pass them on to someone who will.
if you really want infinitys with emits, buy some. there are lots of them to choose from on the market all the time. they have matched components, and they were designed by people who knew what they were doing (until about 1993). there are some emit-equipped sleepers out there still to be had at bargain prices, but be aware that as you go up the infinity food chain it only gets more expensive. not only the speakers, but what it takes to drive them.
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I had no idea the EMIT had such poor horizontal dispersion measurements especially when(at the time) Infinty claimed near perfect horizontal dispersion characteristics.
I've never felt the Infinitys with EMITs beamed and certainly never noticed a narrow sweet spot as one gets from a Magneplanar.
I've never felt the Infinitys with EMITs beamed and certainly never noticed a narrow sweet spot as one gets from a Magneplanar.
sansuigold99
Active Member
I haven't learned how to do multiple quotes quite right...
You both give excellent points against the "dark thought", things I hadn't quite thought of. I am no sound engineer, so altering the crossover beyond its factory parameters would be a guessing game for me. Plus, the price of the Emits is up there with the Walshes, so no benefit there. Sage advice there, guys.
I asked Patrick, the maker of those new Walsh tweeters on that bid site, about using my old ones for rebuild, and he said it's an option BUT to quote him,
"...but these tweeters are 35+ years old now and many loose the sound output level by up to 50% and if you had one out of the two do this, your speakers loose balance and that magical sound that the Walsh tweeters provide."
I would tend to spring for those new ones he makes (where else would you get new ones?) than use some originals, based on his info. I'm not super anal about having a "100 point" restoration, and would be fine with their being close in appearance to the originals, and sounding a lot better.
Since you don't have much invested in them and for the sake of originality, I'd definitely obtain a pair of working Walshes.
As to the Emits, they are, in essense, a super tweeter usually crossed over at 4kH and utilized quite well by Infinity for the purpose of extended well disbersed high frequencies
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but I'd leave the speaker (re)designing to the experts
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If I had the boxes, receipts and manual, I'd consider my cloth-topped Monitor IIas mint:yes:.
As to the Emits, they are, in essense, a super tweeter usually crossed over at 4kH and utilized quite well by Infinity for the purpose of extended well disbersed high frequencies
,but I'd leave the speaker (re)designing to the experts
.If I had the boxes, receipts and manual, I'd consider my cloth-topped Monitor IIas mint:yes:.
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Coastsider
Curmudgeon
I have been fairly accused of being very anal regarding the 100% original condition of my Infinity speakers and I just ordered a pair of Patrick's new Walsh tweeters and will be evaluating them in my Monitor IIa's. I have sufficient spares to replace most of the Walsh's in the three pair of speakers I own that are equipped with them but I am intrigued by the fact that these new Walsh's are constructed to be all but identical to the originals cosmetically while improving on the design and functionality from an engineering standpoint and am anxious enough to evaluate them to spring for what I suggest is an attractive price point for what they represent - a new and possibly better replacement for a 35+ year old very fragile driver that is becoming increasingly more difficult to find in good cosmetic and working condition.
I feel compelled to add that I am in no way affiliated with this product or it's creator/vendor except as a customer.
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loquatious
village elder
as long as we've got some other monitor IIa owners in the mix, id like to ask something.
on your IIa's, how much clearance do you have between the top of the walsh's center support tube and the underside of the wood top? (naturally, measured when both walsh and top are installed properly). i have fairly decent clearance with the fabric top, but my wood tops are only a hair's width away from physical contact with the support tube, which bugs me.
this is something i am curious about re: the "new" walshes, and why i'm overjoyed that coastsider will be evaluating some. i can think of no one better qualified to assess them.
probably better suited to one of the walsh threads, but i have many questions. how will they fit? are they the same height as originals? can you use the original mounting holes? how is the maker (i take it his name is patrick) attaching the center support tube to the magnet structure? gluing, or drilling and threading? if he's doing any machining, are any contaminants introduced to the delicate voice coil area? how is he attaching the aluminum cone to whats left of the titanium dome? is he addressing the natural corrosion that occurs over time with aluminum in contact with titanium? is the spider comparable to the "specially designed" spider of the original? he is currently playing with center tube height because he hasn't got the foam properly domed. is that issue going to be addressed? what foam is he using? etc, etc, ect.
if the answers are good, there is an improvement in sound, and life expectancy of the new drivers seems reasonable, i'll buy some. i'd keep my originals in a safe place though.
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on your IIa's, how much clearance do you have between the top of the walsh's center support tube and the underside of the wood top? (naturally, measured when both walsh and top are installed properly). i have fairly decent clearance with the fabric top, but my wood tops are only a hair's width away from physical contact with the support tube, which bugs me.
this is something i am curious about re: the "new" walshes, and why i'm overjoyed that coastsider will be evaluating some. i can think of no one better qualified to assess them.
probably better suited to one of the walsh threads, but i have many questions. how will they fit? are they the same height as originals? can you use the original mounting holes? how is the maker (i take it his name is patrick) attaching the center support tube to the magnet structure? gluing, or drilling and threading? if he's doing any machining, are any contaminants introduced to the delicate voice coil area? how is he attaching the aluminum cone to whats left of the titanium dome? is he addressing the natural corrosion that occurs over time with aluminum in contact with titanium? is the spider comparable to the "specially designed" spider of the original? he is currently playing with center tube height because he hasn't got the foam properly domed. is that issue going to be addressed? what foam is he using? etc, etc, ect.
if the answers are good, there is an improvement in sound, and life expectancy of the new drivers seems reasonable, i'll buy some. i'd keep my originals in a safe place though.
.
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Coastsider
Curmudgeon
I guess I'll pipe in on this question first as usual and hope that others will as well.
I had to reinstall one of my wood tops as I have been running my IIa's with the cloth tops since they became a topic of conversation in this thread and having done so find that indeed the clearance between the top of the support tube and the bottom of the wood top is very small indeed, perhaps 3/32", something about which I apparently hadn't paid much attention in all the years I've owned them or more likely did notice at some point and just forgot. Maybe that's why the Infinity brochure for the IIa talks about the cloth tops providing the Walsh's with perfect acoustic transparency with more room to breath. The new Walsh's I am getting will have what Patrick described as a 4" support tube as was the original length which hopefully, with whatever other differences there may in the base of the driver, will not bring the top of it any closer to the wood top and might be a good question to ask him while the build is still in progress.
As far as all of your other questions about the new drivers, I am happy to present them to Patrick but would suggest that he may rightfully feel unwilling to share certain proprietary information. There may however be some facts relative to your questions that he would be willing to add to his listings for the benefit of the more technically inclined prospective buyers which I feel would be more appropriate than that information being presented here.
Finally, once I get mine and install them in my IIa's and have allowed myself ample time to get some impressions that I am ready to share, I'd be happy to start a new thread specific to the topic.
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sansuigold99
Active Member
What midrange do I need to be looking for for my Monitor IIa? Are there other speakers that employed the same one? I see a listing on E*** for a bunch out of a Quantum that look the same. He is advertising "5 hole"...is that what I need? Thanks.
No.
You need the 2 1/2" Peerless softdome midrange, as opposed to the 1 1/2, to be authentic and I suppose to sound "correct".
Coastsider
Curmudgeon
2 1/2" midrange
Here's a shot of the 2-1/2" midrange dome in one of my Monitor IIa's. The spec sheet for the IIa on the Infinity Classics website describes the midrange dome as 3.8 centimeters or 1-1/2" but the pictured driver is original in my IIa's that I purchased new. In the color brochure the specs section also says the midrange dome is 1-1/2" but in the text of the brochure in the description of the midrange section it is called a 1-7/8" dome so apparently things were still in flux when the documentation and advertising material was being produced. My second incomplete pair of IIa's that are currently stored in the garage also have what appear to be their original 2-1/2" midrange domes, however my in service Monitor Jr's have the original 1-1/2" dome mids that the Quantums also shared so it looks like the larger 2-1/2" dome midrange was unique to the Monitor IIa as tubed suggests.
Here's a shot of the 2-1/2" midrange dome in one of my Monitor IIa's. The spec sheet for the IIa on the Infinity Classics website describes the midrange dome as 3.8 centimeters or 1-1/2" but the pictured driver is original in my IIa's that I purchased new. In the color brochure the specs section also says the midrange dome is 1-1/2" but in the text of the brochure in the description of the midrange section it is called a 1-7/8" dome so apparently things were still in flux when the documentation and advertising material was being produced. My second incomplete pair of IIa's that are currently stored in the garage also have what appear to be their original 2-1/2" midrange domes, however my in service Monitor Jr's have the original 1-1/2" dome mids that the Quantums also shared so it looks like the larger 2-1/2" dome midrange was unique to the Monitor IIa as tubed suggests.
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sansuigold99
Active Member
Say, Coastsider, see'ins how you seem to have a nice pair of Monitor IIa's there, could you snap a pic of the mounting of the woofer? I have attached a pic of mine after installing one of the replacement woofers. The hole looks kinda rough; I think the original owner cut it up to fit some aftermarket woofers in there, and was wondering what it is supposed to look like. I was thinking of painting the wood black so it didn't stand out. Thanks.
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Coastsider
Curmudgeon
No problem.
The camera flash makes the doping look weird but otherwise it shows the mounting that you requested. The edge of the frame is flush with the face of the cabinet.
The camera flash makes the doping look weird but otherwise it shows the mounting that you requested. The edge of the frame is flush with the face of the cabinet.
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loquatious
village elder
your woofer mounting hole does look a little chewed up, but the opening seems to be the stock diameter. it might have been routed out a little to change the mounting flange depth of the cabinet, but it would be hard to machine the opening much deeper and still leave enough meat for the screw to bite in. are your screws getting a good grip? since you have access to him, i'd ask the original owner if he messed with it. cosmetically, a little touch up with black paint or magic marker will help the aesthetics a lot.
one question: when you installed the woofer did you use a gasket between the woofer basket and the cabinet? infinity originally used a 1/2" wide foam tape as a seal. though the seal on a ported cabinet is less critical than a non-ported one, the gasket does space the woofer out from the cabinet a little and insulates from vibration. you can get the foam tape at parts express (their part # 260-542), or some like to use rope calk instead.
oh, and the midrange is frequently mis-identified as being sourced from peerless. however, the evidence points to it actually being sourced from braun.
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Hi Loq.
I've only heard that the mids were sourced from a subsidiary of Peerless in W. Germany.
Infinity sourced the early softdome tweeters from Peerless.
I've neverheard of any relationship between Braun and Infinity.
Any "evidence" you could kindly supply would clear up this misconception.
Cheers.
loquatious
village elder
a while back, some 1.5" dome mids showed up on parts express as "factory buyouts" that looked just like the ones infinity used. the ad copy said they were made in germany, and alluded to their performance being "like" braun or ADS mids.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=279-104
i contacted PE and asked about them (they'd already sold out). PE said the drivers were, in fact, braun. they were a discontinued item, and PE bought out the remaining factory inventory of NOS drivers. PE said part of their agreement with braun was they could not advertise the mids as braun at the price point they were selling them at. so PE just listed them as being from germany and "like" braun or ADS.
well, braun certainly was in west germany, and certainly used their own drivers in their own speakers. it is also well documented that similar mids used in ADS speakers were sourced from braun.
braun seldom marked their drivers, or only marked them with a small sticker that said only "braun" and was easily lost or removed. one of the tell-tale characteristics of the mids in question are the precariously routed and easily damaged tinsel wires, which is a braun trademark.
if you go on google, and do an image search for "braun midrange" or "braun dome midrange" you will find numerous examples of braun mids with their tinsels exposed. many don't even have the protective coating on the tinsels. if you do the same search for "peerless midrange" or "peerless dome midrange" you won't find any examples with the tinsels so exposed.
infinity did source various drivers from peerless, including the tweeter used on the monitor IIa. part of the confusion about the dome mids comes from their similar look to that peerless tweeter (that tweeter was also used on some polk models). similar mounting plate, similar treated fabric dome, etc.
peerless took some design cues from braun (the success of the braun driver was not lost on them). but the danes (peerless was made in denmark) had too much common sense to hang their tinsels out in the air. they made similar looking drivers to the braun, but always tucked the tinsels into a recessed channel for at least some protection (the dome tweeter on the monitor IIa is a good example). they also tended to angle the tinsels at 45º .
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http://www.parts-express.com/pe/showdetl.cfm?Partnumber=279-104
i contacted PE and asked about them (they'd already sold out). PE said the drivers were, in fact, braun. they were a discontinued item, and PE bought out the remaining factory inventory of NOS drivers. PE said part of their agreement with braun was they could not advertise the mids as braun at the price point they were selling them at. so PE just listed them as being from germany and "like" braun or ADS.
well, braun certainly was in west germany, and certainly used their own drivers in their own speakers. it is also well documented that similar mids used in ADS speakers were sourced from braun.
braun seldom marked their drivers, or only marked them with a small sticker that said only "braun" and was easily lost or removed. one of the tell-tale characteristics of the mids in question are the precariously routed and easily damaged tinsel wires, which is a braun trademark.
if you go on google, and do an image search for "braun midrange" or "braun dome midrange" you will find numerous examples of braun mids with their tinsels exposed. many don't even have the protective coating on the tinsels. if you do the same search for "peerless midrange" or "peerless dome midrange" you won't find any examples with the tinsels so exposed.
infinity did source various drivers from peerless, including the tweeter used on the monitor IIa. part of the confusion about the dome mids comes from their similar look to that peerless tweeter (that tweeter was also used on some polk models). similar mounting plate, similar treated fabric dome, etc.
peerless took some design cues from braun (the success of the braun driver was not lost on them). but the danes (peerless was made in denmark) had too much common sense to hang their tinsels out in the air. they made similar looking drivers to the braun, but always tucked the tinsels into a recessed channel for at least some protection (the dome tweeter on the monitor IIa is a good example). they also tended to angle the tinsels at 45º .
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Coastsider
Curmudgeon
I have a pair of those NOS dome mids and they are identical to the one's in my Monitor Jr's. The only identifying markings on them are the words "Made in W. Germany" that are cast in relief in tiny letters in one corner of the underside of the plastic frame casting, what appears to be the letters "A o v" also in relief in another corner, and the numbers "37 1-6" in relief in yet a third corner with the "1" purposely scratched out on both drivers. The impedance, 8Ω, is stamped in white ink or paint on the back of the magnets, something that Peerless was in the habit of doing on the paper cones of many of their drivers.
That's about as much as I can contribute to the solution, or possibly add to the confusion of the "mystery" of the genesis of these drivers.
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loquatious
village elder
the white "Ω" is food for thought, but is really not conclusive evidence either way. the "made in w. germany" gives more credence to the braun origin. braun was a german manufacturer, peerless was not. peerless took pride in their "made in denmark" origin of their drivers.
infinity seems to have stipulated the drivers they bought be devoid of the manufacturers' name or logo. the implication being they didn't want someone else's branding associated with an infinity product (unless they had a licensing agreement, i.e., walsh or watkins). this is not uncommon practice, though some identical drivers found in other manufacturers' speakers did retain source info.
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infinity seems to have stipulated the drivers they bought be devoid of the manufacturers' name or logo. the implication being they didn't want someone else's branding associated with an infinity product (unless they had a licensing agreement, i.e., walsh or watkins). this is not uncommon practice, though some identical drivers found in other manufacturers' speakers did retain source info.
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sansuigold99
Active Member
Thanks Cs, that helps.
I think my woofers are sitting in a little too far. I didn't put any "gasket" behind them, but that would be a good idea. I have some foam tape at work called Armaflex, used for wrapping pipes, that I might trim to 1/2" and install. There is enough wood to hold a screw but I'm not tightening them very tight.
There is a guy on E*** that repairs the 1 1/2" mids in Quantums, and I asked if he could repair mine, but haven't heard back yet. They seem to be the same just smaller, right?