Greetings from Canada. I'm a new member here and have some questions about the Acoustat Spectra 1100 speakers. I know literally nothing about them and cannot find the specs for them. I am looking for a pair of speakers that would mate well with an old vintage Epicure M1 power amplifier that I recently purchased and entirely restored to almost "as new" condition. The owners manual of the amplifier says that it is rated for 125w/ch - though typically over 150w/ch@8ohm. Mine however was benched at the techs at 186w/ch. The manual says that it is stable to dead. Now there's no information on the pairing into the various impedance. My old Denon POA 2800 was 200w into 8ohm and 350w into 4ohm however I have no idea what, or if, the Epicure M1 does the same.
Wondering if the Acoustat 1100 Spectra would be a good option for this particular amplifier due to - after reading some of your posts on dyaudio - the Acoustat calls for 4ohm-2ohm capability....no?
Lastly, the fellow is asking $275.00 for them. Says they are in very good condition, has all the parts though replaced the 8" drivers with Dayton Audio RSS210HF-4 which specs are:
Product Specifications
Would this be worth the investment? I know absolutely nothing about the Acoustat line only a bit from reading on the web. Never saw or listened to a pair before. My alternative was/is a pair of ADS910.
Thank you so much in advance and kind regards...
Jer
Wondering if the Acoustat 1100 Spectra would be a good option for this particular amplifier due to - after reading some of your posts on dyaudio - the Acoustat calls for 4ohm-2ohm capability....no?
Lastly, the fellow is asking $275.00 for them. Says they are in very good condition, has all the parts though replaced the 8" drivers with Dayton Audio RSS210HF-4 which specs are:
Product Specifications
- Nominal Diameter 8"
- Power Handling (RMS) 280 Watts
- Power Handling (max) 560 Watts
- Impedance 4 ohms
- Frequency Response 27 to 1,000 Hz
- Sensitivity 83.5 dB 1W/1m
- Voice Coil Diameter 2"
- Magnet Weight 50 oz.
Would this be worth the investment? I know absolutely nothing about the Acoustat line only a bit from reading on the web. Never saw or listened to a pair before. My alternative was/is a pair of ADS910.
Thank you so much in advance and kind regards...
Jer
Here you can find info on them.
The panel impedance drop to 1 ohm for some frequencies, see the diagram in the link above. However I've never had a problem driving my Spectra 11 panels even with budget home cinema receivers from Denon and Onkyo.
Seems like a good price considering just the replacement drivers costs $200 new. Of course I would advice you to inspect and listen to them before buying them.
If you have the possibility I would suggest that you bi-amp them and remove the passive XO filter. Buy a miniDSP or similar and use your amplifier to drive the panels and buy a cheap class D amp with lots of power to drive the Dayton 8" drivers. This will give you the cleanest sound and possibility to tune the frequency curves for a perfect match.
Thanks very much. Very interesting stuff there. Didn't know that these speakers were that mailable, if that's the proper word, to tune them. I'll be posting more on these things should I pop on them. I appreciate the information very much. Greatly appreciated...
I can't comment on the suitability of that particular amplfier to drive the Acoustat Spectra 1100. Although it is a relatively 'difficult' load, many amplifiers don't seem to have any trouble driving them. Most people choose the speaker first, and then find a suitable amplifier, but there's no saying the process can't be done the other way around.
That is a VERY good price for the Spectra 1100, especially if that's the pair price. In fact, it's such a good price that I would suggest proceeding with caution, as I can't help but wonder if something is wrong with them.
The replacement woofer may be a 'better' woofer in the absolute sense, but how well it integrates with the ESL is another question. The original crossover was designed specifically for the original woofer, so unless the crossover was also modified, the new woofer may not be as good as it could be.
My suggestion would be to listen before you buy, preferably using your amplifier. This will answer whether your amplifier is up to the task, and also whether the speaker is operating to your satisfaction.
Good luck and gave fun!
Thanks very much. The sad reality is that they are a four hour drive away. The seller says are in superb/excellent condition. Apparently still has all the original driver etc. - perhaps simple foam job? No idea. I was thinking on taking a chance just the same. I know the amplifier is a very sturdy beast from their being used in both home and - pre-digital - cinema systems with excellent reviews by past and present owners.
I do know that the amp is stable under all the various ohm loads and has the ability to connect 3 sets of speakers @ 186w/ch so I thought of the option of bi-wiring these Spectra with an extra channel open for additional set of out door speakers....
This purchase will most likely be a "hail Mary" purchase or let slide.....simply due to the distance of them away....
I do know that the amp is stable under all the various ohm loads and has the ability to connect 3 sets of speakers @ 186w/ch so I thought of the option of bi-wiring these Spectra with an extra channel open for additional set of out door speakers....
This purchase will most likely be a "hail Mary" purchase or let slide.....simply due to the distance of them away....
Hi
I am a new member based in South Africa. Before registering I saw a PDF document that had all the available mods to Acoustats. I have had a pair of 44s for about 25 years and I am generally happy with them. I would like to modify the interface if it is a good idea. I am also enquiring as to the viability of getting a model 2 or 3 and lying on it side to use as a centre channel - any thoughts
I am a new member based in South Africa. Before registering I saw a PDF document that had all the available mods to Acoustats. I have had a pair of 44s for about 25 years and I am generally happy with them. I would like to modify the interface if it is a good idea. I am also enquiring as to the viability of getting a model 2 or 3 and lying on it side to use as a centre channel - any thoughts
I am not aware of any published modifications for the 44 or any of the other Spectra models. As the Spectra series represented the pinnacle of Acoustat's achievement, there really isn't much that can be done to them, in my opinion. The documents you refer to above were for the older MK-121 based speakers.
I don't have much experience with center channel speakers (I'm a strict two-channel man myself). But one of the older speakers, like the Model 2 or 3, either in its intended vertical position, or turned on its side, would probably serve well for a center channel. I would be more inclined to try it in its normal vertical position first, to see how well it works.
The Spectra series would probably be less well suited to a center channel speaker, due to their asymmetric dispersion pattern.
Hi can anyone help. I am an avid fan of accoustats had Model 2's 3's and now I think 2+2. The power unit behind the speaker is MK 2146. It also has "44" on them. I drive them with Steinhart Bolero 350 watt valve amps. I am using these as the fron speakers in a 7 channel suround sound system - front end by Emotiva UMC 200. Issues: Does the "C" mod work with these or is there a mod that can be done - had these for over 25 years? If I wanted use two amps to drive them what do I need to do? (Below 100Hz handled by subs on all 7 channels.) If I get hold of a model three or a 2+2 can I mount this sideways between the left and right accoustats?
Your speaker is the Spectra 44, as indicated by the MK-2146 interface and the 44 stamped on the nameplate. The same interface is used on the larger Spectra 66, but with an internal wiring change to accomodate the larger panel area.
The "C-Modification" applies only to the earlier MK-121 series, and has no application to any of the later Spectra models.
The Spectra series use two identical twin-secondary transformers, one for each phase of the push-pull. Therefore, there is no opportunity for biamping the speakers in the traditional sense. I suppose you could drive each transformer with a seperate amplifier (operating full range) but I'm not sure there would be any advantage to that arrangement.
As mentioned in my earlier response to you, you could use one of the earlier (non-Spectra) models as a center channel, but I suggest you try it first in its normal vertical position before attempting to turn it sideways. A speaker turned sideways may produce a center-channel image that is far too wide, and of course it would also be limited in its vertical dispersion.
I have a pair of Acoustat Spectra 3's that I bought brand new longer ago than I can remember. I'd like to get their interfaces refurbished as I'm sure they need upgraded caps, etc. Is there anyone in AZ that does these refurbs, or anyone that sells refurb kits? I'm pretty good with a soldering iron and I have quite a bit of electronics expertise, and am not afraid of doing it myself. I just need to know what to replace, with what, etc and any guidance and parts kits or availability would be appreciated.
Thanks for any assistance,
Scott
Thanks for any assistance,
Scott
The main difference with the 4400 is a wooden strip with a metallic insert along the side of the speaker and the shape of the sides of the speakers they are angled whereas the 44 is not..otherwise the same. I have a 5.2 system with Spectra 6600 as fronts, 4400 as rears and the model 1 on the horizontal directly under the plasma tv. I modified them slightly by centering the panel in the frame..It works very well and integrates just perfectly. Sometimes I substitute a pair of 1+1's for the 4400's when I have my secondary system which agaiin is the 4400 as the fronts with 1+1 as rears and the other model 1 on its side.
Your answer is correct, but allow me to emphasize that the ONLY difference between the Spectra 44 and 4400 is cosmetic. The interface and panels are exactly the same. The 4400's enhanced appearance was done purely for marketing reasons. The same comments hold for the Spectra 66 and 6600.
And while I do think that the 4400 and 6600 look more refined than the 44 and 66, the presence of the wood strip and the metal inserts make changing the grille socks a real bitch. Basically, it is impossible not to destroy the metal insert when removing it (it's held on with a very tenacious double-faced tape). So when I changed the grille socks on my 4400's, I removed all traces of the adhesive tape on the wood trim and simply left off the metal strips. I have searched for a suitable replacement strip in a variety of materials (metal, wood, laminate), but so far nothing has struck my fancy.
I have 2 burnt up spectra 11's. I am a very experienced certified technician/technologist; I have figured out crossover problems & can locate replacements. All the HV diodes in the bias circuit are open on both units as well as the 500M Ohm resistors & can't find any info on the Dale 8903 p/n. I can find 500M @ Digi-key @ 2.5W. but I am not sure they are adequate. Can you help? Also do you know the resistance values for primaries & secondaries on both transformers? the site I found for crossover components: Jantzen 4.0mH 20 AWG Air Core Inductor Crossover Coil + non-polarized caps are available at a very reasonable cost. I have also found some burnt low cost resistors that I am not concerned about because i can get them anywhere, but I am reluctant to proceed until I am sure I cam verify the transformers' integrity. I hope you can help getting these puppies up & running.
Thanks,Robb
Thanks,Robb
Keep in mind that the multipler diodes are the high-voltage type, and cannot be measured like a regular diode. They are actually constructed of several junctions in series, and an ordinary ohmeter does not have enough voltage to forward-bias the 'stack' of diodes. Normally these diodes are pretty reliable, and they are not likely to fail due to over-driving the speaker. Based on the burnt resistors, I suspect this is what caused your speaker to fail.
Likewise, measuring the 500M-ohm resistor is not possible with an ordinary ohmeter, and these resistors are also unlikely to fail due to over-driving. If you do need to replace these, wattage is not so important as the voltage rating, which should be a minimum of 5-kV. As long as the voltage rating is sufficient, a wattage rating of 2.5 watts should be okay.
Replacing the burnt power resistors is easy and cheap, and I might suggest using a metal-bodied resistor that can be bolted to the interface's chassis for extra heat dissipation. Use short wire leads to connect the resistor to the PC board. I had the same problem with my own Spectra 1100's, and I used this type of resistor with good results.
I will measure the DC resistance of the transformer's windings, and send you the results in a few days. Although the transformer can be damaged by over-driving, it is pretty robust and is probably okay. Keep in mind that measuring the DC resistance is only a crude check for shorted windings. The transformer could be only partially damaged, and might not show any signs of trouble until subjected to the high voltages of normal operation. If you do need new transformers, I believe there are still some available on eBay from some sellers who bought old Acoustat stock.
I might suggest replacing the non-polarized electrolytic with a polypropylene type, if you are interested in a sonic upgrade for a few extra dollars. Solen is a good brand that is commonly available and not terribly expensive.
Finally, about the crossover coil. The original coil had some extra resistance intentionally built-in, to help match the levels between the woofer and ESL. Most commercially available coils will be lower in resistance, therefore, you'll want to add some extra resistance in series with the coil to compensate for the difference. I'll try to provide the DC resistance of the coil, if possible. The coil in the Spectra 1100 is different so I don't have one to measure (unless I have one in my junk box?)
Will reply again in a few days with the resistance values. I'm pretty confident we can get your speakers running again.
Thank you for your prompt response.
After 39 years in electronics I did not know that about multiplier diodes although I worked on TVs that used them. I questioned whether my DMM was capable of 500M Ohm--I thought not. I thought it odd nothing in the bias supply looked burnt. I have a schematic that indicates the coil is 3.75mH/2.5Ohm. The one I am considering is 4.0mH/2.04Ohm which I feel is close enough that it would be hard to hear any difference in bass response considering component tolerances. Thanks
After 39 years in electronics I did not know that about multiplier diodes although I worked on TVs that used them. I questioned whether my DMM was capable of 500M Ohm--I thought not. I thought it odd nothing in the bias supply looked burnt. I have a schematic that indicates the coil is 3.75mH/2.5Ohm. The one I am considering is 4.0mH/2.04Ohm which I feel is close enough that it would be hard to hear any difference in bass response considering component tolerances. Thanks
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The audio transformer consists of two identical coils on the same core, each with a primary (black wires) and a secondary (gray and violet wires). The primary has a DC resistance of around 0.9 ohms, and the secondary has a DC resistance of about 477 ohms.
That coil is a good choice. If you don't like the results, you can always remove a few turns to lower the inductance, and add some series resistance.