No highs, not electrical
Problem with Spectra 33 -- no highs from right speaker (left most panel) and what sounds like diminished mids (lack of "presence"). I have been talking to Joe E. about this problem and after verifying that it is not the interface(s), not the electronics and the consensus is that the panels are virtually indestructible we have concluded that the problem is in the wiring. This leaves a bad connection at one of the full range pins (white or blue), a wire itself, or the wire attachment at the panel. I can resolder the pins although they both appear good. I can disassemble the white and blue wire packets (not the bias) from the pins to the panels and wiggle the wires. The question I have is how are the wires attached to the panels? I have not tries to loosen or remove the panel; I am not sure what to expect and fear irrecoverable damage.
Your thoughts would be appreciated. Thank you.
Problem with Spectra 33 -- no highs from right speaker (left most panel) and what sounds like diminished mids (lack of "presence"). I have been talking to Joe E. about this problem and after verifying that it is not the interface(s), not the electronics and the consensus is that the panels are virtually indestructible we have concluded that the problem is in the wiring. This leaves a bad connection at one of the full range pins (white or blue), a wire itself, or the wire attachment at the panel. I can resolder the pins although they both appear good. I can disassemble the white and blue wire packets (not the bias) from the pins to the panels and wiggle the wires. The question I have is how are the wires attached to the panels? I have not tries to loosen or remove the panel; I am not sure what to expect and fear irrecoverable damage.
Your thoughts would be appreciated. Thank you.
Have you checked the fuses in the interface. Not the ac fuse accessible from the back but the ones inside?
But they are all full range. It makes no sense that only high frequencies are missing. Panels in my Monitor 3 and Model 3 have terminal bolts for the wires which are fastened on with nut and lock washer. Yours are also 3 wire panels. As far as I know they are all the same. Have you checked to see if they need to be tightened?
Spectras are very different from the older Model 3 and similar. They are variable-width, segmented speakers, so not all panel segments produce full range. I'm helping to diagnose this problem off-line.
The Monitor Series was available either with a transformer interface, or with a high-voltage, direct-drive amplifier, called a "servocharge amplifier". The transformer interface is driven by a power amplifier, and the servocharge amplifier is driven by a line-level signal, such as a preamplifier. If this particular pair of Monitor 3's is being driven directly from a CD player, then it must be equipped with the servocharge amplifier.
The Model 3 in the example was available only with a transformer interface, so therefore must be driven with a power amplifier.
Acoustat's original Model X was available only with the servocharge amplifier, The Monitor Series was available with either servocharge or transformer interface, and all other models after that were transformer interface only.
OK, I did not know that the Monitors also came with transformers. I have the Monitor 3s with the servo amps (one side not working, some bad capacitors, resistors somewhere, need to trace it).
But in the above there is mention of a Leach power amp also which must mean it has transformers but then he also says "driven direct." That is why I was confused.
The post you are referring to talked about TWO different pairs of speakers: a Monitor 3 with servocharge driven by a CD player, and a Model 3 with transformers driven by a power amplifier.
Yes, the Model 3 facing to the rear have Medallion 121-2-A interfaces and driven by a pair of Leach Superamps. The forward facing Monitor 3 are servo charge OTL driven. Together as you see them, they sound incredible.
Ah that makes sense. So the Model 3s are sitting upside down?
What is the rationale behind that? To increase that radiating area and have more bass?
Upside down is just to save space at this point. So far what I'm discovering is simply the elimination of the partial obstruction caused by the felt backing on the panels? Not sure about that but what I am sure of is the huge dynamic increase across the entire FB. They project much more powerfully even at low spl. More substance. I'm sure distance between plays a large part in how they sound so once I figure that out I will attach the panels of the Model 3 to the Monitor 3 on a semi permanent detachable diminutive frame in a curved array to match the Monitors.
Why not try running them all of the servo amps? I bet the added load will not make that much difference and you will avoid phase differences and other problems.
Apparently the amps can handle up to 4 panels max. What I need is another pair of servo charge OTLs.
What we all REALLY need are high voltage transistor amps. Finally there are HV transistors, like 5-10kV, but they are few in number and possibly expensive. Maybe even a Class D amp. But that would need to be very well screened. Otherwise you will have 200kHz radio station! But it would be so small. As it is I use a switching power supply module for the HV bias. It is the size of a match box. It was $30 on eBay, made for medical use, for separation of blood serum. Works flawlessly.
Not yet. But read my earlier post:
http://www.diyaudio.com/forums/planars-exotics/183168-acoustat-answer-man-here-167.html#post4990656
I know they are Martin Logans but same thing. I used to drive them with Monitor 3 servo amps but this one is better.
Could someone please shed some light on something? I was listening to Sultans of Swing on my 2+2's, standing in the sweet spot enjoying the sound. For whatever reason I looked down and all of a sudden the top end absolutely came alive. I raised my head again and the sound became muffled. I pressed my chin to my chest and it was like I was listening to a completely different song. What. The. Hell. Is this some psychoacoustic phenomenon I am unaware of or a by product of room issues or simply bad hearing? It is truly an amazing difference in the top end. Literally, I am hearing sounds with my head lowered that DO NOT EXIST when I look straight ahead.
That's a new one on me. You said this happened when you were standing: do you experience the same effect in the seated position? Do you have highly reflective floors?
I any case, I rather doubt this is an issue with your speakers, so you might try re-posting your inquiry in one of the more general DIYAudio forums, where your question would be exposed to a larger audience.
It also occurs while seated. I posted the question here because many people say the Acoustats roll off at the top quite drastically above 14-15khz. My question is whether some high frequency information exists that is somehow obscured by certain room resonances or canceled out, and for whatever reason, tilting my head forward alleviates this phenomenon. Personally, I think it is room related. It is a huge space- 25' wide x 60' long x 30' tall. The front walls are very "live" as they are mostly glass. Lots of furniture, but also lots of open wall space. Floor is hardwood with oriental rugs covering most of the wood.