I'll let Andy answer the first two questions and the fourth. As far as screws/bolts are concerned, I've always used McMaster-Carr. They have just about everything!
McMaster-Carr
You can get new power supplies here:
New Acoustat Spectra 11 12V 130mA AC Adapter Power Supply SA 35TT-5 | eBay
(Maybe Andy can confirm these are the correct ones).
McMaster-Carr
You can get new power supplies here:
New Acoustat Spectra 11 12V 130mA AC Adapter Power Supply SA 35TT-5 | eBay
(Maybe Andy can confirm these are the correct ones).
The recommended transformer to use is 15 volts AC. The internal circuit rectifies and filters the AC, which powers a high-frequency oscillator driving a transformer, which in turn feeds a diode-capacitor voltage quintupler to produce the 5 kV necessary for the electrostat's operation. You'll see both 12 VAC and 15 VAC "Acoustat" transformers for sale on eBay. I recommend the 15 VAC version, but really, any suitably sized "wall wart" transformer will do.
McMaster-Carr is a very good source for hard-to-find hardware, but you can probably find cheaper w/free shipping elsewhere. Those bolts are fairly common.
I suggest you charge the speakers for a few hours before playing. You may hear some "crackling" during initial charging. Then play some music to see if you have any problems. Don't forget there's a right and left speaker: it sounds weird if you get them backwards.
I've attached a schematic of the Spectra 2200/3300 MK-2123, as well as a procedure for checking/adjusting the bias.
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Thanks for your replies. I found decent hardware this morning--not identical but close enough to see if the speakers can be properly "assembled". I see the tilt brackets are crazy loose, I don't want to disturb my nearly pristine socks to address that. I expect there is (supposed to be) a t-nut inside the frame, hopefully it isn't rattling around loose inside the frame!
The label on the 3.5mm jack of the MK-2123 remains a puzzle: 12-15V AC and 15-20V DC? Odd.
I just purchased a pair of power supplies on ebay: Acoustat 120 VAC-15 VAC TTA35TT, A7300-01 Speaker Transformers Adapters 15 Volt. They should be here in a couple days.
Thanks to Mr. A. A. Man for the schematic and bias procedure. I will use both.
FYI: I've only owned "Florida" Acoustats in the past, this is my first pair of "Arizona" Acoustats. First attempt at power up will be in about two hours.
The label on the 3.5mm jack of the MK-2123 remains a puzzle: 12-15V AC and 15-20V DC? Odd.
I just purchased a pair of power supplies on ebay: Acoustat 120 VAC-15 VAC TTA35TT, A7300-01 Speaker Transformers Adapters 15 Volt. They should be here in a couple days.
Thanks to Mr. A. A. Man for the schematic and bias procedure. I will use both.
FYI: I've only owned "Florida" Acoustats in the past, this is my first pair of "Arizona" Acoustats. First attempt at power up will be in about two hours.
Well, my Spectra 22 are up and running. I replaced most of the phillips head 1/4-20 screws with socket head screws, the speakers are solid now. No issues with any t-nuts or threads. Acoustat construction quality is way beyond what I observe in my Magneplanars or QUAD ESLs. I wonder what a pair of Spectra 22 would retail for if they were being built today...
The speakers have been charging for just an hour or two. Probably not enough based on the performance of my other ESLs.
My observations so far: The frequency balance is skewed a bit, to my ears, to the low side. On some music I am lowering the volume below my preferred listening level to avoid making the walls rattle and . The 22s go low, maybe 1/2 an octave (or more) lower than my Magneplanar SMGA and MMG--which will be a good thing if I can figure out a way to pad the woofer segment down a bit. The prodigious bass output makes the somewhat tentative top end come across as even weaker. Male vocals carry more weight than I am used to hearing with the QUAD ESL or MMG. Close mic'ed female vocals are better than I remember coming from my "Florida" Acoustats.
I see that I do have the L and R speakers swapped, i.e. tweeters are on the outside. I will swap them around and note any differences I observe.
The speakers have been charging for just an hour or two. Probably not enough based on the performance of my other ESLs.
My observations so far: The frequency balance is skewed a bit, to my ears, to the low side. On some music I am lowering the volume below my preferred listening level to avoid making the walls rattle and . The 22s go low, maybe 1/2 an octave (or more) lower than my Magneplanar SMGA and MMG--which will be a good thing if I can figure out a way to pad the woofer segment down a bit. The prodigious bass output makes the somewhat tentative top end come across as even weaker. Male vocals carry more weight than I am used to hearing with the QUAD ESL or MMG. Close mic'ed female vocals are better than I remember coming from my "Florida" Acoustats.
I see that I do have the L and R speakers swapped, i.e. tweeters are on the outside. I will swap them around and note any differences I observe.
In that case maybe I don't have the speakers swapped left for right. I should have marked the speakers before I re-mounted the interface boxes.
They sound less bass-heavy today. It may be that the tweeter segment diaphragms take longer to charge.
Some of the deepest, coherent bass I have ever heard came from Dayton-Wright XG8 and from the Acoustat Model 6 (or 8) I heard at the "company store" in the Ft. Lauderdale area while the interfaces from my Model 2 were updated by the factory years ago. Bass from big ESLs can be substantial and impressive. The amount of air they move creates a different feeling for me than what I experience from big Wilsons, MBLs, etc.
So far the Spectra 22 seem to go way lower than I remember my 2 or 2M did. That strikes me as a odd as I expect the Spectra have less panel area dedicated to bass frequency production.
Does anyone know if the HV bias in the Spectra shuts down when the speakers are inactive?
They sound less bass-heavy today. It may be that the tweeter segment diaphragms take longer to charge.
Some of the deepest, coherent bass I have ever heard came from Dayton-Wright XG8 and from the Acoustat Model 6 (or 8) I heard at the "company store" in the Ft. Lauderdale area while the interfaces from my Model 2 were updated by the factory years ago. Bass from big ESLs can be substantial and impressive. The amount of air they move creates a different feeling for me than what I experience from big Wilsons, MBLs, etc.
So far the Spectra 22 seem to go way lower than I remember my 2 or 2M did. That strikes me as a odd as I expect the Spectra have less panel area dedicated to bass frequency production.
Does anyone know if the HV bias in the Spectra shuts down when the speakers are inactive?
Okay... I finally took a look at the MK-2123 schematic provided by AAMan (thanks for that). I can see the internal DC powered oscillator powered via bridge rectified 15VAC or via Vin(DC) after a forward voltage drop in one leg of the bridge. Got it.
The Spectras have been running for 48 hours now and haven't misbehaved or upset anyone so far. Good. This contrasts with the "modern" planar magnetic speakers that were removed from the system after an hour or two for producing listener fatigue.
I remember seeing a diagram showing the frequency ranges supported by the four "segments" in the 22s.
For the Spectra 22 I am currently using for the right channel it seems to be (looking at the front of the speaker):
UL: MF + LF
UR: Full range
LL: LF
LR: Full range
Should I try swapping the left and right speakers?
The Spectras have been running for 48 hours now and haven't misbehaved or upset anyone so far. Good. This contrasts with the "modern" planar magnetic speakers that were removed from the system after an hour or two for producing listener fatigue.
I remember seeing a diagram showing the frequency ranges supported by the four "segments" in the 22s.
For the Spectra 22 I am currently using for the right channel it seems to be (looking at the front of the speaker):
UL: MF + LF
UR: Full range
LL: LF
LR: Full range
Should I try swapping the left and right speakers?
The superior transformers in the Spectra series could be responsible for your impression of stronger bass. Please note the entire surface area (four segments) of the Spectra 22 is devoted to bass reproduction. Three of the four segments also produce midrange frequencies. One of the segments also produces high frequencies (in other words, plays full range). All sectors are the same in construction. This is a variable-width speakers, not one with separate drivers for different frequencies.
The bias system is active whenever it's powered, as it should be.
![spectra_sectors5B15D[1].jpg](/community/data/attachments/617/617571-a83fd3f88482011c08f4438920d2ca1b.jpg)
I don't understand your designations, but what you should hear on the right speaker is the full range segment (where the high frequencies come from) as the second segment from the left edge, as viewed from the front. Conversely, on the left speaker, you should hear the high frequencies coming from the second segment from the right edge of the speaker, as viewed from the front.
If you don't hear the high frequencies as described above, you may have connected the panels incorrectly to the interface. Make sure you properly distinguish the blue group of wires from the white group, and then follow the color coded wires and corresponding terminals within each group. Failure to have the panels wired correctly may result in frequency imbalances, as well as imaging irregularities.
Thanks for the tips MrAG. I ordered the TTA-35TT adapters (15VAC) and they have already arrived and are performing their duty. Nice.
FYI: My old "Florida Acoustats" featured fully internal supplies. The natural hum of the step-down transformers rigidly bolted to the walls of the interface boxes must have been close to the resonant frequency of the diaphragms... I could hear the hum from across the house late, on several occasions I needed to unplug them to get relief. Acoustat sent felt washers to decouple the transformers. The washers had zero effect, they worked better as ear plugs. When I first saw the wall packs charging the newer Acoustats I was not impressed. Now I appreciate their utterly silent service.
Thank you tyu for the diagram. That was helpful. I have not seen a planar speaker organized this way before. Assuming the segments are physically identical, experimentally re-ordering them should be easily executed via wire swapping without changing the loading on the audio frequency taps.
The frequency balance is improving (i.e. brain reprogramming aural nets) but is still limiting overall volume control setting. I like the Spectra's LF extension versus my planar magnetics but the "home theater bass levels" are not a positive. 2 or 3 segments providing bass instead of all 4 may have been better for me. I never had this issue with the Model 2 or 2M. I think these speakers could play Big Band jazz and Reference Recording's Requiem at realistic levels save for the bass overloading the room before reaching realistic levels.
FYI: The speakers are symmetrically placed along a short wall of a 14'x36' space. This placement works well with other planar speakers, but none of them go as low as the Spectra 22s. I observed plenty of output at 31.5 Hz. And audible output below 25 Hz. My other speakers don't go that low. The 22s are pulled out of the corners as far as I dare go with opaque black monoliths. Turns out the physical transparency of M-L CLS attracts less (negative) attention in terms of room decor. I made a note: Next time M-L Statements, not Model 6/8/6600
I made a note: Next time M-L Statements, not Model 6/8/6600
If I could buy a pair of E2's for the price of 6/8/6600, that would be SWEET!
I've heard hundreds and hundreds of different speakers and very few left a lasting impression. The Statement E2 was one, along with the Infinity IRS, the big Soundlabs, the HQD system and the Magnepan Tympani.
Complete systems, the mbl Master Reference System is probably the best I've ever heard, (in the proper room).
Yes, sometimes the old bias transformer could emit an audible hum. In later production, Acoustat mounted the transformer with rubber grommets, which all but eliminated the issue.
The primary motivation behind Acoustat's change to the Ultrasonic Bias Power Supply was to get around worldwide safety agency approvals. By using a wall transformer that was approved by multiple safety agencies, and having only low voltage AC feeding the interface, the interface circuitry no longer fell under the scrutiny of safety agencies. Acoustat's foreign importers appreciated this change, as they needed only to source a wall transformer that matched the local voltage and plug style.
The Ultrasonic supply also has two performance advantages over the original supply: it is both regulated and adjustable. Therefore, the bias voltage doesn't change with varying mains voltages, and the bias voltage can be adjusted for an exact value, yielding a better match between a given pair of speakers.
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Understood. Meeting European safety standards (electrical and hazmat) can be troublesome. I worked on the elimination of CR2025 and CR2032 lithium "button batteries" on PC motherboards to meet Euro standards.
Anyone here old enough to remember the Koss 1/1A ESLs? I've heard them a few times. As I recall some of them used batteries to power an oscillator based charge pump for dc bias. I've got boxes of 9V batteries for smoke detectors... I'll have to try battery-supplied bias so I can compare the sound of Energizers to Duracells
I've been reading these messages for years. I have two sets of Acoustats and my 1100s are now sounding like a bowl of Rice Crispies (boy do I feel the pain); still have 2200 Spectras to enjoy though. I've removed all those staples and blow it out and now Ill need to look at the caps/resitors/ect...I bought them as the company was being moved to Germany from one of the engineers. Any feedback is welcome; otherwise, I'll keep reading this stream of information that comes in handy.
Are the speakers making crackling noises? Does the noise occur all the time (i.e. even when no music is playing) or does it only happen when music is playing?
The 1100's, as I plug in the transformer from the wall will sound crackling and then (as a bowl of Rice Crispies with milk just poured on them) calm down a bit. The crackling is continuous though weather a signal is applied or not. These were stored for the last 10 years in cover in my non air conditioned storage shed (I live near the old Acoustat Office in AZ). The crackling measures around 55db and the hz is around 1000 to 8000.