Amen to that. I think my Spectra 11s sound amazing for the price I paid, I can't even begin to imagine how good the bigger models sound. Unfortunately they are very rare here in Sweden, and shipping them is a pita, so I may never have the fortune of hearing or owning oneBecause of guy's like Andy & Mike and a few others that i know of, a little flattery is well deserved, those gentleman are not obliged to do what they are doing, for them it's the love of speakers that have been out of business for more than 20 years, BUT there still alive because of guy's like them hats off to all of you Acoustat's proud owners, like i have said many many times before, it may not be the best speaker out there, BUT dollar for dollar they are very very hard to beat.
The support on this forum is really excellent, thanks guys.
Amen to that. I think my Spectra 11s sound amazing for the price I paid, I can't even begin to imagine how good the bigger models sound. Unfortunately they are very rare here in Sweden, and shipping them is a pita, so I may never have the fortune of hearing or owning one
The support on this forum is really excellent, thanks guys.
If memory serves, only the 1 center panel (2 if it's a full height model) in the Spectra models has the 5-wire Spectra config, with the outside panels (as in a 33, 6600, etc.) being normal 3-wire panels. I assume this means that if you can get a hold of additional panels you could build new frames to create a larger Spectra model. Just a thought.
I think you could use 2 of the panels per channel, either in a 1+1 config or side by side like a Model 2. M2 style you would wire 1 panel as a Spectra with the other as a standard panel. I may be mistaken in this, so perhaps someone with more experience with Spectras will chime in. If this can be done, you may be able to do away away with the woofer due to the increase in panel area. AFAIK, only the single panel Acoustats used dynamic woofers, & most people prefer Acoustats run full-range, even with external subs added.
Actually, in order to properly use additional panels and remove the dynamic woofer, I think you might need different transformer interfaces. I'm quite familiar with working with non-Spectra Acoustats, but I think the interfaces on the Spectra 11 might not be proper for doing this.
There's a question about driving two panels with one Spectra 11 interface at Acoustat Spectra 11 electrostatic speaker. It seems to be possible get the panels down to 100 Hz in this configuration. That suit me well as I have subs that can take over at 100 Hz. My knowledge on electronics and electrostats is very limited, so any tips on how to do this modification is much appreciated.
That question on audiocircuit was answered by none other than AcoustatAnswerMan (Andy Szabo) so hopefully he can add to that. I think two Spectra panels in a 1+1 config or side-by-side + subs could achieve some great results. Would require building new frames, but you can build frames superior to what Acoustat made, considering they had to work to a tight price point.
First, let me clear up a few misconceptions presented above…
Acoustat panels with only three wires are quite old, and pre-date the Spectra models by more than a decade. I don’t know for sure when Acoustat switched to the 5-wire panels, but I would guess in the early 80’s. The difference is that 3-wire panels have a connection to only one end of each stator, whereas the 5-wire panels have a connection to both ends of each stator. Although there is a supposed improvement in performance with the 5-wire panels, the 3-wire and 5-wire panels can be used interchangeably.
All Spectra panels have 5 wires, PLUS the stators are split so that each vertical half of the panel can be driven by different signals. All Spectra models use the same panel, regardless of the total number of panels in the speaker. The only difference is how they are driven.
Now on to your specific question…
The audio transformer in the Spectra 11 or 1100 was designed to drive one panel, although they can probably drive two panels. I have no information on how well it might work, as we never tried it at the factory (although I always wanted to!). At the very least, you’ll probably need to change the high-voltage sector resistors to one-half of their original value. This will keep the sector roll-off at the same frequency, despite the transformer driving twice the capacitance.
I would recommend only the stacked configuration, similar to the Model 1+1. Placing two panels side-by-side, like a Spectra 22 or 2200, would not really make sense, since you have only a high's and mid's, and mid’s-only signal from the Spectra 11 interface system. A proper full-range side-by-side has three signals available from the interface: full-range, mid’s and lows, and lows only.
If you want the ESL to go down to 100 Hz, you’ll also need to change the value of the input coupling capacitor, to lower the roll-off frequency. I may not have answered all of the possible questions you have about such a modification, so feel free to ask more questions. And if you do try it, please let me know the results, as I am curious to know how well it works!
Acoustat panels with only three wires are quite old, and pre-date the Spectra models by more than a decade. I don’t know for sure when Acoustat switched to the 5-wire panels, but I would guess in the early 80’s. The difference is that 3-wire panels have a connection to only one end of each stator, whereas the 5-wire panels have a connection to both ends of each stator. Although there is a supposed improvement in performance with the 5-wire panels, the 3-wire and 5-wire panels can be used interchangeably.
All Spectra panels have 5 wires, PLUS the stators are split so that each vertical half of the panel can be driven by different signals. All Spectra models use the same panel, regardless of the total number of panels in the speaker. The only difference is how they are driven.
Now on to your specific question…
The audio transformer in the Spectra 11 or 1100 was designed to drive one panel, although they can probably drive two panels. I have no information on how well it might work, as we never tried it at the factory (although I always wanted to!). At the very least, you’ll probably need to change the high-voltage sector resistors to one-half of their original value. This will keep the sector roll-off at the same frequency, despite the transformer driving twice the capacitance.
I would recommend only the stacked configuration, similar to the Model 1+1. Placing two panels side-by-side, like a Spectra 22 or 2200, would not really make sense, since you have only a high's and mid's, and mid’s-only signal from the Spectra 11 interface system. A proper full-range side-by-side has three signals available from the interface: full-range, mid’s and lows, and lows only.
If you want the ESL to go down to 100 Hz, you’ll also need to change the value of the input coupling capacitor, to lower the roll-off frequency. I may not have answered all of the possible questions you have about such a modification, so feel free to ask more questions. And if you do try it, please let me know the results, as I am curious to know how well it works!
Thanks for the reply Andy.
With your explanation and the Spectra 11 schematics things are starting to clear up. Let me see if I got it right. There are five wires that connect to the Spectra 11 panel:
- blue and white are connected to one half of the stators, high and mid freqs (> 250 Hz) are sent here
- black and yellow are connected to the other half of the stators, only mid freqs (250 - ? Hz) are sent here
- red is connected to the diaphragm
When you write that one interface can drive two panels you mean that same-colored wires should be connected in parallel to both panels. Placing the two panels stacked vertically will create a more balanced sound image than placing the panels side-by-side.
Did I get everything correct so far?
Now for some questions:
- At what frequency is the high vs mid split in the high-voltage section?
- Wouldn't it be better to connect the mid-only wires to both sections of the extra panel? Wouldn't this make it possible to place the panels side-by-side and still have good high frequency dispersion? Or would this result in an imbalanced frequency response?
- Would it be possible to drive the panels down to (or close to) 100 Hz in a two panel setup?
- When you write that the high-voltage resistors should be replaced, do you mean the two 330K resistors between the stator connectors?
Thanks in advance.
With your explanation and the Spectra 11 schematics things are starting to clear up. Let me see if I got it right. There are five wires that connect to the Spectra 11 panel:
- blue and white are connected to one half of the stators, high and mid freqs (> 250 Hz) are sent here
- black and yellow are connected to the other half of the stators, only mid freqs (250 - ? Hz) are sent here
- red is connected to the diaphragm
When you write that one interface can drive two panels you mean that same-colored wires should be connected in parallel to both panels. Placing the two panels stacked vertically will create a more balanced sound image than placing the panels side-by-side.
Did I get everything correct so far?
Now for some questions:
- At what frequency is the high vs mid split in the high-voltage section?
- Wouldn't it be better to connect the mid-only wires to both sections of the extra panel? Wouldn't this make it possible to place the panels side-by-side and still have good high frequency dispersion? Or would this result in an imbalanced frequency response?
- Would it be possible to drive the panels down to (or close to) 100 Hz in a two panel setup?
- When you write that the high-voltage resistors should be replaced, do you mean the two 330K resistors between the stator connectors?
Thanks in advance.
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When I had Spectra 11's replacing the electrolytic capacitor crossing over the panel to a polycap made a significant increase in performance to my ears. Then upon suggestion from someone on the Apogee forum I replaced the polycap with a piece of wire running the panel full range and that sounded better still. I never heard any audible distortion from the panel and ran them that way for years without any problems.
I assume you disconnected the Spectra woofers then? Did you have some external high pass filter and a sub for the lower range (I don't think a single Spectra panel can be driven down to 40 Hz)?
I have a digital crossover filter in my amp (up to 250 Hz), so in theory I could disconnect the Spectra woofers and bypass the internal panel high pass filter. Would that risk damaging the Spectra panel or electronics? Ideally I would want to set the crossover at about 100 Hz.
I found 1100 crossovers on ebay, that allowed me to biamp the panels and woofer. To get the best out of the Spectra 11 imo, is to run the panels full range and put a better 8" in there. Just be aware that running the panels full range presents a harder load for your amplifier. You need a good amplifier to drive low impedance loads, I had a few that did not like the Acoustats, and that only got worse after I ran the panels full range. Ultimately after going down that road I ended up taking the panel out and mating it with various different "subwoofers", all of which I liked better than the 11"s original design. But none of which I thought would be better than to run multiple panels. The Acoustat panels sound amazing and to mate their sound with a cone driver is a very hard thing to do.
Thanks !
Its not the quantity of bass, as they certainly go low and there is more than enough bass. I guess what Im looking for is "dynamic" (for want of a better word) bass, thats tight and tuneful. I find the Acoustat bass, while extendng down far enough, does not have the snap and punch Im used to ?
My most recent speakers have been Infinity Rennaisance 90's and Acoustic Energy AE3 MKII Floorstanders, bit of which are great performers, esp in the bass and upper bass areas.
I guess Im looking for the Acoustats to do everything .... not such a big ask is it ?
Cheers
Scott
One can certainly bypass the input capacitor with straight wire, but doing so can lead to saturation of the transformer, since it is not designed for low frequency operation. This will also lower the low-frequency impedance considerably, making the load more difficult for the amplifier.
A better choice, if one is interested in experimenting with this idea, is to parallel the input capacitor with a 1-ohm, 50-watt resistor. This will largely remove the high-pass filter, while reducing the likelihood of transformer saturation. If going this route, one can also remove the parallel resistor (10-ohm?) in the input network, whose only function is to form the highpass filter along with the capacitor. With the capacitor bypassed with a resistor, the parallel resistor will act as a voltage divider, wasting amplifier voltage swing.
Agree 100%, a hybrid is NOT a full range and yes full range is much harder for the amp i know i have the most difficult of all Acoustat's the 1+1s ( 81 - 82 db ) but for ME the king of three dimensional soundstage at reasonable volume.
Thanks !
Its not the quantity of bass, as they certainly go low and there is more than enough bass. I guess what Im looking for is "dynamic" (for want of a better word) bass, thats tight and tuneful. I find the Acoustat bass, while extendng down far enough, does not have the snap and punch Im used to ?
My most recent speakers have been Infinity Rennaisance 90's and Acoustic Energy AE3 MKII Floorstanders, bit of which are great performers, esp in the bass and upper bass areas.
I guess Im looking for the Acoustats to do everything .... not such a big ask is it ?
Cheers
Scott
Hey Scott, could you please tell me what amplification you are using and please remember that the Spectra 11s - 1000s - where the beginning of the Acoustat line.
Sorry for the double post but i wanted to make a correction but the edit button was GONE it was Spectra 11s - 1100s -
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Im using an Australian made amp, an ME-75. Extremely stable. I have used a variety of this brand over the years. This particular unit drove my Scintillas effortlessly to high levels. Re-capped with Nichicons and biased up to about 15w class A.
My speakers are the Model 6 I believe ? 4 x MK-121 Pwr Supplies, 3 panels across and two high.
Regards
Scott
