The Spectra 11 is a fine speaker, but it was Acoustat's least-expensive model, and to meet it's original retail of $1000/pr, there were some compromises made, particularly in the woofer section. However, assuming this pair is functioning properly, the asking price is a smokin' deal in my opinion. It would be hard to do better for that price.
Note the seller says they have been re-coned, which may or may not have addressed some of the shortcomings of the original woofer.
The Spectra 11's are inefficient, and need lots of power. I'd recommend 100-200 wpc (8 ohm rating) from an amplifier capable of driving low impedances. Pink Floyd deserves no less. At some point, you might consider adding an external powered subwoofer, crossed over in the 80-100 Hz range.
Go listen to them before someone else gets them!
I'd take these in a heartbeat if 6000 miles of ocean weren't in the way. Do you know if any of the Model 8's came out with the Servo amps at all?
The Servocharge Amplifier had been discontinued long before the Model 8 was introduced. So no, none of them were manufactured with direct drive amps. All Model 8's (and Model 6's) were manufactured with two transformer interfaces per speaker, so ideally a pair of speakers would be driven with a total of four amplifier channels.
BTW, those Model 8's were just re-listed on eBay for a lower price. Somebody please BUY these before the seller gives up and trashes them. It's happened before.
Last edited:
Since the Model 3 was Acoustat's longest-lived configuration, produced in several variations, there may be a wide range of selling price. Of course condition of wood and cloth portions will affect the price, too. I would suggest in the range of $500-1500/pair. More towards the top of that range if they have Medallion transformers. Be patient since it often takes a while to find the right buyer who can transport such huge speakers to their new location.
Wood and cloth are in excellent condition. No Medallion stickers on the interface cases. Serial numbers 2053690 & 205370. I've bought new film caps and good resistors to replace all those in the interfaces. Also bought high voltage diodes and caps to replace the ladder HV circuit components (don't know if that's necessary, so I'll check the HV with the high voltage probe I bought). I can offer a price for including all those components and probe and a price with me doing the labor. Doh - I should make this a separate thread.
Spectra panel hum/hiss
Hey AAM, my 33s have devoloped oped an intermittent high piched hum/hiss that I only hear at the very top and bottom of one of the outermost panels. The hum comes and goes, at times reducing to a faint hiss. Other times it gone altogether. Discharging and recharging doesn't correct this. What does work is removal of the panel, Deoxiting the connections and firing it back up. This last time an ever so slight hum returned only to diminish to a hiss after a few days. I've attempted to note a pattern of this intermittancy, even to the point of settling on the possibility that weather may be causing this. I live in California and for a while the phenomenon seemed more present during the rainy season.
My guess is bias related
Have you encountered this situation?
Any ideas how this can be corrected? I've sought out bias adjustment info on the met but have yet to find a step-by-step thread.
Thanks
Hey AAM, my 33s have devoloped oped an intermittent high piched hum/hiss that I only hear at the very top and bottom of one of the outermost panels. The hum comes and goes, at times reducing to a faint hiss. Other times it gone altogether. Discharging and recharging doesn't correct this. What does work is removal of the panel, Deoxiting the connections and firing it back up. This last time an ever so slight hum returned only to diminish to a hiss after a few days. I've attempted to note a pattern of this intermittancy, even to the point of settling on the possibility that weather may be causing this. I live in California and for a while the phenomenon seemed more present during the rainy season.
My guess is bias related
Have you encountered this situation?
Any ideas how this can be corrected? I've sought out bias adjustment info on the met but have yet to find a step-by-step thread.
Thanks
Ground wiring
Andy or Anyone
If I remember correctly, you have a Transnova amp? If so could you do me a favor and measure the resistance from low side of input jack to chassis ground and the low side of the speaker output to chassis ground and low side of input jack to low side of speaker. Would greatly appreciate it. If anyone else has one either Acoustat or Hafler model I'll like the measurements.
Thanks,
MI
Andy or Anyone
If I remember correctly, you have a Transnova amp? If so could you do me a favor and measure the resistance from low side of input jack to chassis ground and the low side of the speaker output to chassis ground and low side of input jack to low side of speaker. Would greatly appreciate it. If anyone else has one either Acoustat or Hafler model I'll like the measurements.
Thanks,
MI
Which Transnova amplifier are you asking about? The answer will likely vary depending on model. I have Hafler 9500 and 9180 but no Acoustat TNT's
This does sound like a bias leak, which often will sound like a hiss or sizzling noise. And if it is a bias leak, it will get worse in conditions of high humidity. Is this occurring in both speakers? If not, try swapping speaker cables from left to right speaker: if the noise moves to the other speaker, the source of the noisee is coming from the electronics driving the speaker, and not the speaker itself.
If the noise is isolated to one speaker (regardless of which amp channel is driving it) then I suspect the speaker. Being intermittent, this may be hard to track down. When it occurs, trying looking for a blue or purple glow either in the panels or around the high voltage parts of the interface. You'll need to do this in a completely darkened room. You might also try sniffing around for a strong, localized odor of ozone. If you do find something glowing or detect ozone, report back and we'll go from there.
If it's in the panel, you may have some foreign material caught in the gap, causing a local discharge. This might be a hair, bug part, or just dust. This is not unheard of, and can usually be remedied by vacuuming and/or using compressed air to clean the panels. An actual defect in the panel causing this would be very unlikely (good news!).
If it's in the interface, you may have a build-up of "high voltage soot" which sometimes forms around high voltage parts. This can cause leakage, too, but can also be remedied by cleaning.
One more question: does the sound level of the speaker drop when the noise occurs? Although a bias leak will not necessarily cause a drop in volume, if you are experiencing a drop in volume, that does help to confirm that you have a bias leak.
Thaanks for the response. Glad to hear that I'm not necessarily crazy in thinking I'm detecting a weather related pattern. Additionally, anthother related pattern is that the hiss seems less likely to occur the more i use the speakers. I'm also a fan high efficiency horns and set amps, which have been getting far more plays time.
And yes, I have done the channel swap, as well as equip swap to verify it isn't an upstream issue.
As far as db drop, this issue does usually result in the eventual loss of output in that one panel.
I am curious to hear your response to the phenomenon of only hearing the hiss/whistle at the top and bottom of the inner 2-3 inches of the outermost panel? If the dirt/dust/foreign particle explanation os so, then it seems its then just a coincidence that it is occong in two locations simultaneously. This panel is very near a door which is often open. The amount of dust and such that regularly blows in here in Cali can be quite frustrating.
Regardless, should I discharge before any vacuuming?
What procautions, procedures and cleaning products should i use to get at the gunk around the high voltage parts?
thanks ahain
And yes, I have done the channel swap, as well as equip swap to verify it isn't an upstream issue.
As far as db drop, this issue does usually result in the eventual loss of output in that one panel.
I am curious to hear your response to the phenomenon of only hearing the hiss/whistle at the top and bottom of the inner 2-3 inches of the outermost panel? If the dirt/dust/foreign particle explanation os so, then it seems its then just a coincidence that it is occong in two locations simultaneously. This panel is very near a door which is often open. The amount of dust and such that regularly blows in here in Cali can be quite frustrating.
Regardless, should I discharge before any vacuuming?
What procautions, procedures and cleaning products should i use to get at the gunk around the high voltage parts?
thanks ahain
Ground
Do your Haflers have a switch to float the signal ground? The TNT schematic shows 5 ohms from signal ground to chassis. I'm debating which way to go with my Transnova design.
Thanks,
MI
Do your Haflers have a switch to float the signal ground? The TNT schematic shows 5 ohms from signal ground to chassis. I'm debating which way to go with my Transnova design.
Thanks,
MI
Sorry for the long delay in responding...sometimes the AcoustatAnswerMan just doesn't feel very Acoustat-ish.
I'm not surprised that you hear the extraneous noise in an isolated area...or two. This lends support to the idea that you have contamination of some sort that is causing bias leakage. Being near an open door could certainly add to the possibility of "crud" getting into the speaker, as well as potentially raising the humidity in that part of the room.
Absolutely yes, you should completely discharge the panel before vacuuming. Any remaining electrostatic force will tend to cling to the debris, making it difficult to remove. You might get lucky and be able to fix this through the grill cloth, but more than likely you'll need to pull the sock and vacuum the panel directly (both sides). A gentle application of compressed air can be helpful, too. Don't despair if this doesn't work the first time, as it can take a few tries before the dirt moves out of its offending position.
At this point in the discussion, I don't think you have a problem of "soot" in the interface. But if you find some and feel inclined to remove it, you can probably use a damp rag (and/or an old toothbrush) with a little detergent to remove it. Obviously, the interface must be completely discharged before you do this, and should be allowed to dry thoroughly before being energized.
This post is a little off-topic for a thread about Acoustat speakers, but I'll offer a brief reply. Based on my experience in amplifier design (and I've been around a few at both Hafler and Acoustat) the grounding in a particular design depends more on the actual physical layout of the parts inside, instead of any particular philosophy or belief in the "right way to do it". Quite often any resistance placed between signal ground and chassis ground is a band-aid to reduce stray ground currents caused by widely separated ground points. So the question of whether to include it in your design will depend on noise measurements when it's all put together.
Ground float switches are never a bad idea (particularly in units with an earth-ground), and are there more for reducing interactions between connected components, rather than any problems in the amplifier itself.
If you'd like to seek other's opinions, I suggest you post questions in the amplifier section.
A tale of Amp(s) for Acoustats
Hi,
I've been away from this forum since last Nov., but just caught up with the postings. One that caught my eye, was from Islandmon way down in the Virgin Islands (had a fabulous week on Sapphire beach a decade ago !!).
Aside from his concerns about corrosion, he was curious about good SS amps for the stats (a perennial question), and I have some recent experience that adds another answer to that question.
A friend of mine traded me some amps and cables for building him a hot-rodded digital source, and music library. Started out with an old Aragon 4004 MkII, which replaced my modded ARC D-52d ('d' for Dave
, which had replaced my favorite Marsh A400s after it crapped out on me
I loved the way the Marsh A400S controlled my Spectra 3300's ! It was delicate, powerful, and just got out of the way. But, alas, it succumbed to a damn Velodyne servo sub failure. I temporarily replaced it with an old ARC D-52b, which sounds only OK, and doesn't have the power to play very loud.
I also lived with an Adcom 5800 SS amp for some months, which was a Nelson Pass design, and a favorite of a longtime local audiophile pro and guru. It had an additional 50 watts of power, which I could hear in the 'Battle' track of the Gladiator movie soundtrack. I could clip the Marsh amp here, but not the Adcom ! The problem is that then the diaphram clipped at a small increase in volume, so not much was gained, and there were ergonomic problems with the Adcom, so I went back to the A400S. But to be fair, I could never detect any significant difference in the sound quality of those two fine (and similar design) amps !
Back to the current year, and the Aragon 4004 II. In 'the day' it was a well regarded amp, and had plenty of power to drive my 3300's, but from the beginning, there was something about the sound that bothered me, and that quality remained through a long burn in, and cable changes. It was Ok, but not exciting.
So my friend replaced the Aragon with... (drum roll please !)... a Crown XLS2400. Wow !!! From the first tracks played after putting this Class D switching amp in my system, I know something was special. But break-in was kind of rocky, with the sound changing even during the first listening session. But after about 2-3 weeks, and with the addition of a nice Nordost XLR interconnect and some vibration isolators, the sound stabilized to something I've never heard before through any of my stats. The closest I can come is back when I had Monitor 4's w/ the original Servo Amps in a small room Well, that and a fine horn system I heard long ago.
I mention horn speakers intentionally, because this Crown amp handles the broad electrostatic/electromagnetic impedance's in the Acoustat speakers like they were nothing ! The macro and micro dynamics are simply astounding to me, who has long accepted the power limitations of the electrostatic speaker type.
What I think is happening here is that the XLS2400 can deliver massive amounts of power into low impedance loads (2400 watts per channel at 4 ohms), and the Manual for my 3300's shows the impedence from 16 down to below 2 ohms. So apparently a significant factor (IMHO).
Bass is not just full, or tight, but visceral, feeling it in your diaphragm ! Recall what a kick drum feels like ? I now find strings to be more solid, apparent and distinct in timbre. As instruments can now express their full power range without any 'sag' in the amp or power supply, they achieve a new dimension of realism, that I didn't think my stats could do ! Not only the incredible sonic performance, but the amp is small and light (11 lbs). The face is a bit busy with a small blue screen and a couple of blue LEDs, but so much easier to deal with then most monster amps, tubed or SS.
Ok, time for the caveat, which might not be a big deal, depending...
I discovered this past spring that I have developed a significant hearing loss, knocking on the door of needing a hearing aid for speech in noisy places. This is, as you can imagine, quite a blow for a long time audiophile and DIYer
But, one has to take life as it is, and I can still enjoy listening to music, even if the top octaves are now MIA The changes in my hearing involve some frequency's becoming unpleasant, not just attenuated, so I have to be careful to discount that in my 'critical' listening. In fact, I half suspect that my continuing problem with the Aragon amp may be related to that effect (unknown at the time), and not so much the amp ?
So the upshot of this is that I can't really evaluate the high frequency sound quality of the XLS2400. If it's bad, I can't hear it, and don't care, because what I can hear, I love ! That amp is staying in my system for the duration.
But then I can't predict how it will perform for any other Acoustat owner in the upper frequency's. I'm ecstatic with the sound quality up to the lower female vocal range (inc. harmonics). Above that I won't say anything else; you'll have to listen for yourself. But if you do give the Crown XLS2400 a listen, I will say you will enjoy the experience, even if you don't end up keeping it.
BTW, this a Pro Audio product and not very expensive at all ($600). I think the XLS line has been superseded by a newer one (2402 ?), but I don't know anything about them... Google is your friend
Cheers, Dave
Hi,
I've been away from this forum since last Nov., but just caught up with the postings. One that caught my eye, was from Islandmon way down in the Virgin Islands (had a fabulous week on Sapphire beach a decade ago !!).
Aside from his concerns about corrosion, he was curious about good SS amps for the stats (a perennial question), and I have some recent experience that adds another answer to that question.
A friend of mine traded me some amps and cables for building him a hot-rodded digital source, and music library. Started out with an old Aragon 4004 MkII, which replaced my modded ARC D-52d ('d' for Dave
, which had replaced my favorite Marsh A400s after it crapped out on me I loved the way the Marsh A400S controlled my Spectra 3300's ! It was delicate, powerful, and just got out of the way. But, alas, it succumbed to a damn Velodyne servo sub failure. I temporarily replaced it with an old ARC D-52b, which sounds only OK, and doesn't have the power to play very loud.
I also lived with an Adcom 5800 SS amp for some months, which was a Nelson Pass design, and a favorite of a longtime local audiophile pro and guru. It had an additional 50 watts of power, which I could hear in the 'Battle' track of the Gladiator movie soundtrack. I could clip the Marsh amp here, but not the Adcom ! The problem is that then the diaphram clipped at a small increase in volume, so not much was gained, and there were ergonomic problems with the Adcom, so I went back to the A400S. But to be fair, I could never detect any significant difference in the sound quality of those two fine (and similar design) amps !
Back to the current year, and the Aragon 4004 II. In 'the day' it was a well regarded amp, and had plenty of power to drive my 3300's, but from the beginning, there was something about the sound that bothered me, and that quality remained through a long burn in, and cable changes. It was Ok, but not exciting.
So my friend replaced the Aragon with... (drum roll please !)... a Crown XLS2400. Wow !!! From the first tracks played after putting this Class D switching amp in my system, I know something was special. But break-in was kind of rocky, with the sound changing even during the first listening session. But after about 2-3 weeks, and with the addition of a nice Nordost XLR interconnect and some vibration isolators, the sound stabilized to something I've never heard before through any of my stats. The closest I can come is back when I had Monitor 4's w/ the original Servo Amps in a small room
Well, that and a fine horn system I heard long ago.I mention horn speakers intentionally, because this Crown amp handles the broad electrostatic/electromagnetic impedance's in the Acoustat speakers like they were nothing ! The macro and micro dynamics are simply astounding to me, who has long accepted the power limitations of the electrostatic speaker type.
What I think is happening here is that the XLS2400 can deliver massive amounts of power into low impedance loads (2400 watts per channel at 4 ohms), and the Manual for my 3300's shows the impedence from 16 down to below 2 ohms. So apparently a significant factor (IMHO).
Bass is not just full, or tight, but visceral, feeling it in your diaphragm ! Recall what a kick drum feels like ?
I now find strings to be more solid, apparent and distinct in timbre. As instruments can now express their full power range without any 'sag' in the amp or power supply, they achieve a new dimension of realism, that I didn't think my stats could do ! Not only the incredible sonic performance, but the amp is small and light (11 lbs). The face is a bit busy with a small blue screen and a couple of blue LEDs, but so much easier to deal with then most monster amps, tubed or SS. Ok, time for the caveat, which might not be a big deal, depending...
I discovered this past spring that I have developed a significant hearing loss, knocking on the door of needing a hearing aid for speech in noisy places. This is, as you can imagine, quite a blow for a long time audiophile and DIYer
But, one has to take life as it is, and I can still enjoy listening to music, even if the top octaves are now MIA
The changes in my hearing involve some frequency's becoming unpleasant, not just attenuated, so I have to be careful to discount that in my 'critical' listening. In fact, I half suspect that my continuing problem with the Aragon amp may be related to that effect (unknown at the time), and not so much the amp ?So the upshot of this is that I can't really evaluate the high frequency sound quality of the XLS2400. If it's bad, I can't hear it, and don't care, because what I can hear, I love ! That amp is staying in my system for the duration.
But then I can't predict how it will perform for any other Acoustat owner in the upper frequency's. I'm ecstatic with the sound quality up to the lower female vocal range (inc. harmonics). Above that I won't say anything else; you'll have to listen for yourself. But if you do give the Crown XLS2400 a listen, I will say you will enjoy the experience, even if you don't end up keeping it.
BTW, this a Pro Audio product and not very expensive at all ($600). I think the XLS line has been superseded by a newer one (2402 ?), but I don't know anything about them... Google is your friend
Cheers, Dave
I got one of the XLS 2500 for $250 used off cl....vary nice amp for driving any of Acoustats are even the Sound labs M1s ....even the old Magnepans.....only my Sunfire 300 sounds better...have fun with class D power for less....
Crown made by Harman/Mark levinson people..... go fig...right
Crown made by Harman/Mark levinson people..... go fig...right
(edited) I got one of the XLS 2500's for $250, used off of Craigslist. A very nice amp for driving any of the Acoustats, or the Sound labs M1s, or even the old Magnepans. Only my Sunfire 300 sounds better.
Have fun with class D power for less.
Crown is made by the Harman/Mark Levinson people. Go figure
See, it's not hard to communicate with good spelling, punctuation, and grammar. Then more people can understand your message, and may even respect it/you more that way