I don't recall any changes to the Spectra 11 woofer during its production run. If there were any changes, they were not intentional design changes, but rather minor cosmetic changes due to vendor supply changes.
More than likely someone changed the woofers in one of your pairs. The woofer is the weak point of the Spectra 11, so changing the woofer to a better one has been done by a few owners. And no, I don't have any recommendations for a better woofer: the people who have done this don't seem to be sharing the information, or they didn't know what they were doing and only made it worse. (A better woofer in the wrong application is not better!)
Hi there I’m new to all this so please be patient
I have recently become the owner of a pair of Acoustat hybrid sold have connected them up
With great anticipation and I get bass and midrange with very distant top end as is evident something is wrong power supply plugs in rear between binding posts and is 12volts ac
I unscrewed the top of the sub enclosure to reveal the circuit board all seems ok will probably need to replace the two transformers caps and resistors etc also I can not identify a model and I’ve been looking please find attached photos
I have recently become the owner of a pair of Acoustat hybrid sold have connected them up
With great anticipation and I get bass and midrange with very distant top end as is evident something is wrong power supply plugs in rear between binding posts and is 12volts ac
I unscrewed the top of the sub enclosure to reveal the circuit board all seems ok will probably need to replace the two transformers caps and resistors etc also I can not identify a model and I’ve been looking please find attached photos
Attachments
This is interesting. What I see inside is the components for a Spectra 1100, but I am unfamiliar with the external appearance. This was not made by Acoustat in the USA - I am wondering if this is one of the models briefly produced in Italy? Or perhaps a home-brew modification?
Attached is a schematic and board layout for the Spectra 1100. I don't see the connections to the Hi-Frequency contour switch, and if it is absent, you will get the least amount of highs, although the difference between high, low, and medium positions of the switch is not huge. I would start your investigations there. If there is no switch, you can replace the switch with a piece of wire, which will give you maximum HF output.
Let me know what you find out.
You should also be aware that the Spectra 1100 (and presumably your variation, too) are left and right, mirror-image pairs. They should be oriented left and right so that the highs are coming from the outer edge of each panel. Having them backwards will do weird things to the imaging and may also affect the perceived HF balance.
Hi again Andy and everyonewas wondering does anyone have a recomended site to go to for acoustat parts -im looking for original Spectra 11 drivers
Sorry, there is no one-stop place to go for Acoustat parts. Acoustat ceased production in the USA in 1990, and any parts available at that time were sold to purveyors specializing in surplus goods. You'll still find a few parts available on eBay, but for the most part, those parts have been sold or scrapped after 28 years.
I am quite sure woofers for the Spectra 11 were never available on the surplus market. Those woofers were custom-made at Rockford's Carbonneau division, and would not be available from them today. In any case, the Spectra 11's woofers were its weak point, so you might be better served in fitting a different woofer. Sorry, I don't have any suggestions on that subject. I know some people have substituted other woofers, but I've never heard any details of what they used or how well it worked for them.
This may seem an odd question, but did you have any experience with Dayton-Wright ESLs? I'd be curious to learn how you and your colleagues viewed their performance, reliability, construction quality, or etc.
I seem to recall some KLH-9 speakers around Bell Labs in the late 60's. Unfortunately but for good practical reasons, the "bookshelf" two-way dynamic KLH-6 was the defacto standard around the lab for folks learning how to simulate voices and instruments.
Thanks.
Ben
I seem to recall some KLH-9 speakers around Bell Labs in the late 60's. Unfortunately but for good practical reasons, the "bookshelf" two-way dynamic KLH-6 was the defacto standard around the lab for folks learning how to simulate voices and instruments.
Thanks.
Ben
Acoustat used bias transformers designed for only one voltage: 100, 117 and 220/240 volts AC. Therefore, your transformer cannot be rewired for a different voltage. The part number for the 117V version is TTA117, but it's highly unlikely you'll find a pair today. So, it's likely your only option is to use an external 120-to-220 volt step-up transformer. The good news is that you can power both speakers from one step-up transformer. Power requirements are very low, only about 5-10 watts per speaker. They should be left energized at all times.
Here's one. All of the models with an angled array of panels must be perpendicular to the floor to maintain the same vertical angle. Leaning the speaker changes the orientation of the panels to each other. Seems like an inherent incidental design flaw, huh. They need to be independently adjustable. If they were, I wonder how it would change how they sound
Come to think of it, if you lean a Quad 63, Sound Labs, or even ML, you'll have an infinitely changing vertical angle. Interesting
Come to think of it, if you lean a Quad 63, Sound Labs, or even ML, you'll have an infinitely changing vertical angle. Interesting
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Acoustat Help!
I need help identifying which Acoustats I actually have. Bought them slightly used at a high end stereo store eons ago. They are 7 1/2' tall, about 10" - 12" wide. Looking into grill cloth with flashlight, inside electrostatic {?} panels appear to be stacked on top of each other. The step-up transformer on the back says MK-131-B, serial no. A 03171 (the best I can make out). Can't get to the back of the other one, but it's the same except for the serial no. The speaker wire runs to the subwoofer cube (on rolling wheels!) with a downward firing 10" black-coated woofer (surround has rotted away). Subwoofer cube has the crossover, but no amp. Speaker wire continues on from woofer to the 2 Acoustats. Any help identifying the model I have would be greatly appreciated! Thanks!
I need help identifying which Acoustats I actually have. Bought them slightly used at a high end stereo store eons ago. They are 7 1/2' tall, about 10" - 12" wide. Looking into grill cloth with flashlight, inside electrostatic {?} panels appear to be stacked on top of each other. The step-up transformer on the back says MK-131-B, serial no. A 03171 (the best I can make out). Can't get to the back of the other one, but it's the same except for the serial no. The speaker wire runs to the subwoofer cube (on rolling wheels!) with a downward firing 10" black-coated woofer (surround has rotted away). Subwoofer cube has the crossover, but no amp. Speaker wire continues on from woofer to the 2 Acoustats. Any help identifying the model I have would be greatly appreciated! Thanks!
Those are 1+1's with the optional sub. Well, the sub could be bought with the speakers or added on later. The MK-131-B Interface had separate sub out binding posts to send the signal to the subs, if you had them. I was an Acoustat dealer for many years.
Keep in mind that the MK-131 interface is a limited range interface, intended for use with the companion woofer cube. It cannot be used as a full-range interface. The proper model designation for this set-up is the 1+1S. I doubt that any 1+1S were sold without the woofer, in fact I believe they were sold as a 3-piece set.
The standard 1+1 was supplied with the full-range MK-121 interface, which allowed the panels to be operated full range (within the limitations of the limited panel area of a 2-panel speaker).
Yes, the woofer's foam surround is well known to rot after many years.
2+2 PROBLEM interface
Dear AA
Had problem with severe rolloff in one of my 2+2s. Swapped interfaces and problem is definitely in IF. Followed your instructions and checked all caps...OK
Checked all resistors....OK
Checked all fuses ...OK
Checked LF tap which was on four panel setting
Checked LF transformed... DC OK but could not check impedance or inductance.
Where do I go from here?
Sorry to be so long but having medical problems...diagnosed with cancer and still working with a slew of MDs. Would like to fix this speaker before I pass them on. Any ideas?
Thanks,
Tom
THOMAS J GREGORY
MR. TOAD’S STEREO/VIDEO
2305 FT. HENRY DR.
KINGSPORT, TN. 37664
423-392-1121
Dear AA
Had problem with severe rolloff in one of my 2+2s. Swapped interfaces and problem is definitely in IF. Followed your instructions and checked all caps...OK
Checked all resistors....OK
Checked all fuses ...OK
Checked LF tap which was on four panel setting
Checked LF transformed... DC OK but could not check impedance or inductance.
Where do I go from here?
Sorry to be so long but having medical problems...diagnosed with cancer and still working with a slew of MDs. Would like to fix this speaker before I pass them on. Any ideas?
Thanks,
Tom
THOMAS J GREGORY
MR. TOAD’S STEREO/VIDEO
2305 FT. HENRY DR.
KINGSPORT, TN. 37664
423-392-1121
Have you checked the integrity of the HF balance control? These have been known to develop oxidation (green stuff) on the exposed conductor and contact. Try loosening the adjustable slider and using fine emery paper to clean both the resistor's wires and the point of contact on the underside of the slider. These same comments apply to the older rotary-type HF balance control.
You didn't mention checking the HF transformer - have you at least checked continuity of both primary and secondary?