I haven't torn anything apart yet for my project. Would anyone have the panel length handy? I've searched all over but can't find an answer. Also, I saw on Facecrook someone mentioning he preferred his 2+2s with no angle between the stacks, but he had a relatively large room which I don't. Anyone tried them 180 degrees, i.e., in the same plane?
Hi all,
Is there any technical reason not to use an actual 12dB per octave xover with Spectra 1100s - with the correct inductor in parallel the electrostatic panel. I'm thinking this would give me more flexibility with the crossover point. I want to lower the crossover point without stressing the panel - so thinking of 165 hz. Anyone tried this - any ideas would be welcome. My speakers are singing by the way.
Is there any technical reason not to use an actual 12dB per octave xover with Spectra 1100s - with the correct inductor in parallel the electrostatic panel. I'm thinking this would give me more flexibility with the crossover point. I want to lower the crossover point without stressing the panel - so thinking of 165 hz. Anyone tried this - any ideas would be welcome. My speakers are singing by the way.
Hi,
I have been asked to try to set up a pair of 1+1. I can't get a sound out of them. Neither the current owner or I have any past experience with this pair. They came with a Trans Nova Twin 200 amp. After trying to get them to play, I checked the amp and discovered that it had a problem and was putting 21V out one channel. I substituted a known-good amp and still have no sound. I am confident that I am connecting everything correctly. Did the amp likely toast the speakers?
Thanks
I have been asked to try to set up a pair of 1+1. I can't get a sound out of them. Neither the current owner or I have any past experience with this pair. They came with a Trans Nova Twin 200 amp. After trying to get them to play, I checked the amp and discovered that it had a problem and was putting 21V out one channel. I substituted a known-good amp and still have no sound. I am confident that I am connecting everything correctly. Did the amp likely toast the speakers?
Thanks
Hi, mcdmgb:
The Acoustat panels are pretty robust. Have you tried checking to see whether the fuse on the 1+1s interfaces are blown or not? The fuse holder is right beside the binding posts. If they are blown, replace them with ones of the same values. Otherwise, you may need to open up the interfaces to see if might be some visual clues of burnt/broken parts.
Sincerely,
Kingsley.
The Acoustat panels are pretty robust. Have you tried checking to see whether the fuse on the 1+1s interfaces are blown or not? The fuse holder is right beside the binding posts. If they are blown, replace them with ones of the same values. Otherwise, you may need to open up the interfaces to see if might be some visual clues of burnt/broken parts.
Sincerely,
Kingsley.
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I did check the fuses with a DMM and they seem to be okay, although there did appear to be some scorching on one. I still may replace them just to eliminate that possibility of them being the problem.
I have read elsewhere that the speakers will still pass an audio signal, albeit a weak and distorted one, even if there is an issue with the interfaces. Do you know if this is true? If it is, I don't seem to be getting even this.
Thanks
Hi, mcdmgb:
Scorching on one hopefully is not an indication of a further issue inside the interface.
Also might be a good idea to check/search online (unless you have the manual) for the correct size of the fuse for that particular model. I think most of the fuses were slow blow 3A 250V but increased to 5A later when user's were experiencing blowing fuses . However, if a fuse of larger amperage (A) were swapped in, there is the possibility of a large voltage/surge from the amp travel further into the interface without blowing the fuse. I haven't opened the interfaces on my 1+1s yet so I do not know if there are internal fuses also. If you decide to open up the interfaces, again check visually for burnt parts. Also use your sniffer to detect any burn odor.
As for the passing signal when the fuse blows, I don't remember this being the case with a pair of Models threes I have. When the fuse blows (most times it has to do a spike in power/voltage from the amp during power on), I would think logically, that there will be no voltage for the interface and thereby no power flowing into the interface in order to charge the stators of the panels and in turn produce sound.
Hopefully, Andy (AcoustatAnswerMan), bolderset, or even Tyu, will chime in shortly but given it's the holiday season, some members may be elsewhere enjoying much deserved time away for normal day to day activities.
Keep us updated.
Sincerely,
Kingsley.
Scorching on one hopefully is not an indication of a further issue inside the interface.
Also might be a good idea to check/search online (unless you have the manual) for the correct size of the fuse for that particular model. I think most of the fuses were slow blow 3A 250V but increased to 5A later when user's were experiencing blowing fuses . However, if a fuse of larger amperage (A) were swapped in, there is the possibility of a large voltage/surge from the amp travel further into the interface without blowing the fuse. I haven't opened the interfaces on my 1+1s yet so I do not know if there are internal fuses also. If you decide to open up the interfaces, again check visually for burnt parts. Also use your sniffer to detect any burn odor.
As for the passing signal when the fuse blows, I don't remember this being the case with a pair of Models threes I have. When the fuse blows (most times it has to do a spike in power/voltage from the amp during power on), I would think logically, that there will be no voltage for the interface and thereby no power flowing into the interface in order to charge the stators of the panels and in turn produce sound.
Hopefully, Andy (AcoustatAnswerMan), bolderset, or even Tyu, will chime in shortly but given it's the holiday season, some members may be elsewhere enjoying much deserved time away for normal day to day activities.
Keep us updated.
Sincerely,
Kingsley.
The recommended audio fuse is 3A - 5A slow-blow. This is the externally mounted fuse. If this fuse is blown, you will get no sound from the speaker. If the amplifier had DC on its output, it is very likely the corresponding fuse is blown, AND you may also have internal damage to the interface. If a new fuse blows again, you likely have transformer damage.
There are also (2) internal fuses, on the line side of the bias power transformer. For 120V interfaces, these should be 1/4 A slow blow, or 1/8 A slow-blow for 220/240V interfaces. If either of these fuses are blown you will get no sound from the speaker. Blowing these fuses is rare, and usually indicates a problem with the bias supply. They will not blow due to overdriving, nor will they blow when DC is presented from the amplifier.
The speaker must be plugged into AC power for it to operate. Wait several minutes after being energized to allow the bias voltage to come up and charge the panels.
There are three bundles of wires coming from the panels that must be connected to the PC board in the interface.
There are also (2) internal fuses, on the line side of the bias power transformer. For 120V interfaces, these should be 1/4 A slow blow, or 1/8 A slow-blow for 220/240V interfaces. If either of these fuses are blown you will get no sound from the speaker. Blowing these fuses is rare, and usually indicates a problem with the bias supply. They will not blow due to overdriving, nor will they blow when DC is presented from the amplifier.
The speaker must be plugged into AC power for it to operate. Wait several minutes after being energized to allow the bias voltage to come up and charge the panels.
There are three bundles of wires coming from the panels that must be connected to the PC board in the interface.
Hi,
I am trying to repair / rebuild the bias supply for some Acoustat 1s (MK-141C).
Specifically, I am looking for replacements for the existing 25G10 diodes (5 per speaker) and I cannot find those specifically nor specs for the 25G10 diodes.
I think they are 10 KV reverse and .25 A but not sure. I think each would operate around 1 KV.
I have found some 3 KV, .25 A and some 1N4007 which are 1 KV, 1 A. I would use two of these in series to replace each 25G10 to get 2 KV reverse. I assume the forward voltage drop is not too important in this application.
I am also inclined to just leave the originals in there and just replace the ceramic disk caps if they measure OK.
Also, in the audio circuit after the transformers is a .002 uF, 6KV polypropylene capacitor (C4) that looks like a giant disk. I would like to replace this too, although the originals are probably fine, but cannot find anything polypropylene at 6 KV.
Any advice?
I am trying to repair / rebuild the bias supply for some Acoustat 1s (MK-141C).
Specifically, I am looking for replacements for the existing 25G10 diodes (5 per speaker) and I cannot find those specifically nor specs for the 25G10 diodes.
I think they are 10 KV reverse and .25 A but not sure. I think each would operate around 1 KV.
I have found some 3 KV, .25 A and some 1N4007 which are 1 KV, 1 A. I would use two of these in series to replace each 25G10 to get 2 KV reverse. I assume the forward voltage drop is not too important in this application.
I am also inclined to just leave the originals in there and just replace the ceramic disk caps if they measure OK.
Also, in the audio circuit after the transformers is a .002 uF, 6KV polypropylene capacitor (C4) that looks like a giant disk. I would like to replace this too, although the originals are probably fine, but cannot find anything polypropylene at 6 KV.
Any advice?
Try these diodes:
GP02-40-E3/54 Vishay Semiconductors | Mouser
They have the correct electrical ratings and are a reasonable size to fit the existing pattern on the board. Cheap, too.
Finding off-the-shelf polypropylenes with 6-kV rating will be highly unlikely. Such parts were custom-made for Acoustat by a select group of manufacturers who were willing to tackle such an item. My recommendation is to leave them alone unless you have a known problem.
GP02-40-E3/54 Vishay Semiconductors | Mouser
They have the correct electrical ratings and are a reasonable size to fit the existing pattern on the board. Cheap, too.
Finding off-the-shelf polypropylenes with 6-kV rating will be highly unlikely. Such parts were custom-made for Acoustat by a select group of manufacturers who were willing to tackle such an item. My recommendation is to leave them alone unless you have a known problem.
Thanks for the response and for hosting this thread.
Out of circuit, my Fluke multimeter measures this cap (C4) as .0016 uF which is 20% below the specified value of .002 uF. I cannot find a tolerance spec anywhere, so I will just assume this is Ok (or will have to do).
Also, was considering making a voltage divider to measure the bias voltage on the bench. I was thinking 5, 10-Meg resistors in series would draw 100 uamp (at 5KV) and I could measure the voltage across each of the 5 resistors to see if they add up to 5 kV (my meter goes to 1KV). Will this work or is that too much current draw?
Thanks again.
Virtually any arrangement to measure the high voltage will load the supply, even a purpose-built high voltage probe. So the best one can expect is to verify the presence of high voltage. The actual measurement will depend on how much your method loads the supply.
If you connect a standard DVM, with 10-megohm input resistance, after the 500 M-ohm outfeed resistor, you should measure about 90 VDC. Just be sure not to connect such a meter before the outfeed resistor.
If you connect a standard DVM, with 10-megohm input resistance, after the 500 M-ohm outfeed resistor, you should measure about 90 VDC. Just be sure not to connect such a meter before the outfeed resistor.
OK, I can try this right now on the still good speaker interface but I want to double check this first.
If I connect a DVM (with internal 10-Meg input resistance):
- with the positive DVM lead to the out-feed resistor (where the wire to the speaker diaphragm normally connects to the board), and
- with nothing else, including the speaker diaphragm, connected there, and
- with the negative DVM lead connected to the green wire coming in from the power cord (gnd), and
- where the schematic says "5 kV",
I should be OK and see about 90 VDC and not 5 KV?
Correct?
Thanks again.
BTW, I'm a train geek too.
That is correct. You can also connect the meter's negative lead to the ground point on the board, which is the other end of that green wire. Connect the positive lead to the red pin jack. You may not measure exactly 90V, but since you have a known-good interface, that will provide a benchmark for your measurement method. Connect both leads before applying power, and then remove power and allow the supply to die down before removing the leads.
OK it worked on the good interface: about 75 VDC.
BTW, out of circuit, all of the components on this bias supply board are measuring as pretty good within 20% or better. The out-feed resistor measures 602M which is 20% high and all the capacitors are within 11 % or better except C4 at 20%. All the diodes (when measured as resistors) measure about 20 Meg ohm in one direction with about a +/- 10% variation and around and between .05 and .12 nS conductance (8 to 16 GigOhms) in the other direction (which may not mean much so call it infinity). So, not sure what's up here. New caps and diodes on the way, so we'll see what happens.
Thanks again, much appreciated.
BTW, out of circuit, all of the components on this bias supply board are measuring as pretty good within 20% or better. The out-feed resistor measures 602M which is 20% high and all the capacitors are within 11 % or better except C4 at 20%. All the diodes (when measured as resistors) measure about 20 Meg ohm in one direction with about a +/- 10% variation and around and between .05 and .12 nS conductance (8 to 16 GigOhms) in the other direction (which may not mean much so call it infinity). So, not sure what's up here. New caps and diodes on the way, so we'll see what happens.
Thanks again, much appreciated.
Now that I think about it, maybe 75 VDC was closer to the typical voltage measurement using the DVM method. I don't have my notes at hand.
The diodes are not measurable by any normal means. To get the high voltage rating, the diodes consist of several stacked diode junctions within each case. Typical ohmmeters don't have enough voltage to properly forward-bias the multiple junctions, and therefore they tend to measure "open" or "non-conducting" in both directions.
The diodes are not measurable by any normal means. To get the high voltage rating, the diodes consist of several stacked diode junctions within each case. Typical ohmmeters don't have enough voltage to properly forward-bias the multiple junctions, and therefore they tend to measure "open" or "non-conducting" in both directions.
If you want to see the back story here, go to the link below on Audiokarma.org and scroll down to post #110 on this page. Unfortunately, you will not be able to see the pix unless you have an AK account.
Scotty, I need more power! | Page 6 | Audiokarma Home Audio Stereo Discussion Forums
Scotty, I need more power! | Page 6 | Audiokarma Home Audio Stereo Discussion Forums
Spectra 11 Questions
Hi!
I once owned and forever regret selling a pair of 1+1s. I now have the opportunity to purchase a pair of functioning Spectra 11s and have a few questions about them. I'm hoping the fine people here can answer:
Hi!
I once owned and forever regret selling a pair of 1+1s. I now have the opportunity to purchase a pair of functioning Spectra 11s and have a few questions about them. I'm hoping the fine people here can answer:
- Is the panel run full range, or is it rolled off to cross to the woofer? (edit - found "spectra segments" diagram, showing it's rolled off below 150Hz. Is it possible/advisable to lower the rolloff point, or operate full-range?)
- I've read in this thread about the 2-3KHz peak, caused by resonances in the frame cavity. Has anyone built new, narrower frames to overcome this?
- the woofers may need to be replaced; are the T-S parameters documented somewhere?
- does anyone have a good source for cloth from which to craft replacement grille socks? (edit - found link to DMD Acoustic Fabric)
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