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Old 24th February 2011, 02:28 PM   #1
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Default Acoustat 2+2's

Hey Everyone new here. Just posted to the Subwoofer forum and wanted to post here as well because I'm seeing a lot of information on these great speakers.

I own a pair purchased brand new back in 85. (I think it was around 85 anyway my memory is getting bad) Got um from Boulder Sound Gallery in Boulder Colorado if we have anyone from Colorado around might remember. Good old days.

I love these speakers and to my ear they sound as good now as back when I first bought them.

I tried MANY amplifiers and found the best (within my budget) for overall musicality an Audio Research Classic 60 which I've been driving them with for over 20 years or so. I'm in love with the Classic 60 although my second fav. was a Threshold S-300. Drove them louder but just not with that sweet midrange of the tubes.

I use my 2+2's with a pair of subwoofers X-over 120hz 48db I built from Marchand Electronics (XM16)

Anyway at 25 years old I'm looking to perhaps check into new caps & also replacing that wire-resistor for adjusting high frequencies and or anything else I can find here that other 2+2 owners recommend.

I did find a place in az which sells socks. Already got quote for my Ivory ones 180 so I'm going to order those. At first they said they only had black but emailed me later saying they could do the Ivory.

Anyway thanks for listening and any advise much appreciated. Mean while I'll continue searching and reading what I can find.

Mark
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Old 24th February 2011, 03:43 PM   #2
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Hey Mark: welcome brother. the only caps you really need to replace are the blue NP electrolytic caps 47 or 50 uf at the input. The plastic caps are fine unless you decide that you want to play with some fancy more expensive ones which is fine but it is nnot a necessity. You might want to swap out the internal wire in the interface if you see that there is any oxide on any of the wire at the connections. Do you have the rotary Ohmite resistor or the brown tubular resistor. The Ohmite is a real keaper but there is nothing wrong with the tubular resistor either. Clean the contact amd put some silicon dielectric gel on it to keep it clean and you are good to go to the grave with your stats.
You might want to try running the HT supply's on some good line filters to keep the line noise of your diaphragms Triplite make nice inexpensive units about $30.00 each for a single duplex design. I hope this is of interest and of some use to you. Best regards Moray James.
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Old 24th February 2011, 04:27 PM   #3
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Originally Posted by moray james View Post
Hey Mark: welcome brother. the only caps you really need to replace are the blue NP electrolytic caps 47 or 50 uf at the input. The plastic caps are fine unless you decide that you want to play with some fancy more expensive ones which is fine but it is nnot a necessity. You might want to swap out the internal wire in the interface if you see that there is any oxide on any of the wire at the connections. Do you have the rotary Ohmite resistor or the brown tubular resistor. The Ohmite is a real keaper but there is nothing wrong with the tubular resistor either. Clean the contact amd put some silicon dielectric gel on it to keep it clean and you are good to go to the grave with your stats.
You might want to try running the HT supply's on some good line filters to keep the line noise of your diaphragms Triplite make nice inexpensive units about $30.00 each for a single duplex design. I hope this is of interest and of some use to you. Best regards Moray James.
Cool thanks for the info.

I'm not sure which resistors I have I'll have to open and have a look to refresh my memory. I think I remember they are grey with that round ring around them which slides and then tighten with a screw.

I also "think" my MK 121's were the latest they have both the RED and the BLUE update sticker on them.................. I think the store updated them and left which ever sticker was oldest on the case. (Not sure if RED or Blue was newest)
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Old 24th February 2011, 04:59 PM   #4
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If you haven't yet ordered the sock, I suggest making a new one out of stretched spandex. I replaced my original sock this way for less than what the standard style sock costs, and it looks and (more importantly) sounds better. Less muffled.
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Old 24th February 2011, 07:11 PM   #5
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Replace the electrolytics with polypropylenes, they need not be "fancy"... substantial improvement in the way the speaker images, it moves the upper mids back "in line" with the rest of the sound field. You'll see.

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Old 24th February 2011, 08:51 PM   #6
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Quote:
Originally Posted by Mercury3 View Post
Cool thanks for the info.

I'm not sure which resistors I have I'll have to open and have a look to refresh my memory. I think I remember they are grey with that round ring around them which slides and then tighten with a screw.

I also "think" my MK 121's were the latest they have both the RED and the BLUE update sticker on them.................. I think the store updated them and left which ever sticker was oldest on the case. (Not sure if RED or Blue was newest)
Speakers with a BLUE Medallion label have been upgraded with the Medallion transformers. Although not impossible to upgrade at this point, those transformers are not easy to find.

Speakers with a RED Medallion label have both the improved transformers AND a modification to the high frequency transformer input network. This is fairly easy to do with commonly available parts. If you can't find the "C-MOD" instructions on the Audiocircuit, I can post them here.

By far, the Medallion transformers represent the biggest improvement, although the C-MOD is also worthwhile doing if your speakers don't have it.

I wouldn't bother trying to replace the large gray, 50-watt resistors. Finding resistors of suitable size and wattage will be difficult in any type better than the existing wirewounds. However, there is merit in replacing the electrolytic with a film capacitor (polypropylene etc) in the high frequency input network. If your speaker doesn't have the C-MOD, this would be a good opportunity to make that change too, as the original value of 220-uF will be HUGE to replace with a film type, whereas the C-MOD version uses only 47-uF, which is a much more practical size to replace with a film type.

Concerning the variable resistor for the high frequency balance (whose value also changes in the C-MOD), if you have found your 'sweet spot' for that control, and aren't considering ever changing it, you might want to replace it with two fixed resistors of equivalent value. If you keep the variable resistor, cleaning the contact area and coating with a dielectric grease is recommended, as suggested elsewhere in this thread.
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Old 25th February 2011, 12:28 AM   #7
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Originally Posted by AcoustatAnswerMan View Post
Speakers with a BLUE Medallion label have been upgraded with the Medallion transformers. Although not impossible to upgrade at this point, those transformers are not easy to find.

Speakers with a RED Medallion label have both the improved transformers AND a modification to the high frequency transformer input network. This is fairly easy to do with commonly available parts. If you can't find the "C-MOD" instructions on the Audiocircuit, I can post them here.

By far, the Medallion transformers represent the biggest improvement, although the C-MOD is also worthwhile doing if your speakers don't have it.

I wouldn't bother trying to replace the large gray, 50-watt resistors. Finding resistors of suitable size and wattage will be difficult in any type better than the existing wirewounds. However, there is merit in replacing the electrolytic with a film capacitor (polypropylene etc) in the high frequency input network. If your speaker doesn't have the C-MOD, this would be a good opportunity to make that change too, as the original value of 220-uF will be HUGE to replace with a film type, whereas the C-MOD version uses only 47-uF, which is a much more practical size to replace with a film type.

Concerning the variable resistor for the high frequency balance (whose value also changes in the C-MOD), if you have found your 'sweet spot' for that control, and aren't considering ever changing it, you might want to replace it with two fixed resistors of equivalent value. If you keep the variable resistor, cleaning the contact area and coating with a dielectric grease is recommended, as suggested elsewhere in this thread.
Hey thanks so much this is the info I needed. Let me make sure I understand.

Are you saying the RED sticker means I already have the C MOD? Like I said my units have both the BLUE and RED stickers. I thought they just forgot to remove one when they did the later update but now I see they are seperate updates.

Sounds like if I've got the C Mod I won't have much I need to do. Check into the mentioned caps and possible the two fixed resistors. Yeah I haven't adjusted it in years. Sounds fine where I set it early on.

Thanks to everyone!

Oh, My wife wants me to let her make the socks and save 200 dollars. lol I don't know if she can do it or not. Might have to let her try I think. You know how wifes can be. lol
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Old 25th February 2011, 01:47 AM   #8
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Using spandex for my 2+2 cost about $70 if I remember correctly & there are tons of choices for colors, even patterns if you prefer.
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Old 8th March 2011, 08:07 PM   #9
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Quote:
Originally Posted by Mercury3 View Post
Hey thanks so much this is the info I needed. Let me make sure I understand.

Are you saying the RED sticker means I already have the C MOD? Like I said my units have both the BLUE and RED stickers. I thought they just forgot to remove one when they did the later update but now I see they are seperate updates.

Sounds like if I've got the C Mod I won't have much I need to do. Check into the mentioned caps and possible the two fixed resistors. Yeah I haven't adjusted it in years. Sounds fine where I set it early on.

Thanks to everyone!

Oh, My wife wants me to let her make the socks and save 200 dollars. lol I don't know if she can do it or not. Might have to let her try I think. You know how wifes can be. lol
Your speakers are not supposed to have both Blue and Red labels, but if you have Red labels, it is probably safe to assume you have the C-Mod. More than likely, your speakers were modified twice, once with the Medallion transformers (Blue label) and later with the C-Mod (Red label). Evidently whoever did the second modification didn't remove the Blue labels. To be absolutely sure, look at the electrolytic capacitor in the HF filter - if it is 47-uF, then you have the C-Mod. If it is 220-uF, it is not C-Mod.

Changing the 47-uF capacitor to a film-type is the only upgrade that I would recommend for your interfaces. Changing the variable HF Balance control to two fixed-value resistors should be done only if you are sure you'll never want to change the HF balance.

If you elect to make your own grille socks, I would suggest you start by making a short tube of fabric to test its stretchiness, before commiting to a piece of fabric as large as the speaker. The original Acoustat fabric had quite a bit of stretch to it, so the diameter of the fabric tube, as sown, was smaller than the circumference of the speaker.

FYI, the original Acoustat grille cloth is a double-knit, which does a good job of hiding the ugly innards of the speaker. However, it is not the best at sonic transparency. Using a more shear fabric (i.e. single knit) will likely yield better sound, but will not hide the panels as well. Ah, life is full of trade-offs, eh? (Meaning you should discuss this aspect with your mate, in case cosmetics are an over-riding factor.)
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Old 8th March 2011, 08:43 PM   #10
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THE BIGGEST improvement to the 2+2 . That I have found is to convert the ac pug to an iec and change the power cord. the head in the vise seating position is greatly reduced.
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