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Klimon

Member
Joined 2005
Measuring bias voltage method 2

Just tried to measure bias voltage with my 10Mohm DMM using method 2, but sparks when touching the red terminal & cracking noise from the panels made me decide otherwise :eek: At the next attempt I'll disconnect the panels, but is method 2 intended for standard probes?

Simon, awed by the fierce power on that red terminal... :nod:

METHOD #2: (Alternate) Using a 10 megohm input impedance digital voltmeter, connect the ground (black) lead of the meter to chassis ground (at the solder lug attaching the white wire to the chassis). Apply power via the appropriate wall transformer, and allow the system to stabilize for several minutes. Connect the hot (red) lead of the meter to the red pin-plug terminal (where the panel connections are normally made). DO NOT CONNECT THIS TYPE OF METER TO LOCATION �5KV�. Adjust the trimmer potentiometer on the PC board until the probe reads approximately 75 volts DC. This reading will correspond to an actual 5000 volts, but the measurement is greatly reduced due to the voltage divider effect of the power supply and voltmeter.
 
M

Mendel24

Member
Joined 2015
Discopete said:
It's easy to fault the improvement you hear in saying they are more directional. Rest assured it is an improvement. Doesn't matter what the design is, dynamic or planar or esl. The more precisely you position yourself in the sweet spot, the better they'll sound, period. That the ESLs are more pronounced in this regard is testament to their superiority, not the other way round. They are "head in a vice" in comparison to themselves, not to other speakers. Flat panels need to be toed out, not in or directly at your ears. They should be facing about 10 ft. behind your listening position. In my case that's about 15deg. toed out since I sit about 13ft. away and the speakers are about 8ft. apart, leaning back 3deg. It took around 3 years to arrive at this set up after changing them countless times. It was when I decided to be brave and toe them way out that all of a sudden it became obvious. It's still a very precise geometry. Before I did this I thought I was hearing them at their intended best; not so. The way they are now, a bit more in or out and they lose impact and imaging. So the sweet spot is actually a bit larger than you are probably experiencing right now. And in fact, there is a more pronounced change moving your head forward or back than from side to side within about a 12 inch circumference.
Click to expand...


You toe them out? Not even just straight ahead but toed out? I have not heard of that before for Acoustats. I have them in a small room 11X15 so sit in near field only 8 feet away so not sure toed out would work in my set up. Lots of time to experiment these days anyway
 
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mraudioguru

Member
Joined 2014
Mendel24 said:
You toe them out? Not even just straight ahead but toed out? I have not heard of that before for Acoustats. I have them in a small room 11X15 so sit in near field only 8 feet away so not sure toed out would work in my set up. Lots of time to experiment these days anyway
Click to expand...

I've never heard of toeing them out either? I was an Acoustat dealer, (along with Martin Logan, Magnepan a few other panel types). I've setup well over 100 pairs of such. Not sure what to make of that?

I have the time also, so maybe I'll give it a try on my 2+2's...
 
D

Disco-Pete

Member
Joined 2009
Paid Member
Mendel24 said:
You toe them out? Not even just straight ahead but toed out? I have not heard of that before for Acoustats. I have them in a small room 11X15 so sit in near field only 8 feet away so not sure toed out would work in my set up. Lots of time to experiment these days anyway
Click to expand...
To be clear, toed out 15deg from facing straight at my ears, or toed in but 15deg away from my ears. Sorry for that confusion, my statements can be counter intuitive at times. Another rule I've adopted over the years (and it could be a factor in this present arrangement) is the distance from speaker to front wall should be exactly the same as from your ears to the back wall behind you. So I've found that symmetry as precise as you can get it is very important to optimal performance. I've found this to be true with every speaker I've owned over a 40 year period. My subjective experience for what it may or may not be worth.:tilt:
 
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H

hhhh

Member
Joined 2007
I think "toed out" here is not being used in the sense it's used for automotive wheel alignment, but rather to indicate that perpendicular lines to the panels would meet behind your head rather than at it or in front. I had determined this shortly after I bought mine back in 1981, contrary to what the store recommended, mainly for better image depth and realism. I.e., what most people describe as slightly toed in from being in the same plane.
 
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Disco-Pete

Member
Joined 2009
Paid Member
hhhh said:
I think "toed out" here is not being used in the sense it's used for automotive wheel alignment, but rather to indicate that perpendicular lines to the panels would meet behind your head rather than at it or in front. I had determined this shortly after I bought mine back in 1981, contrary to what the store recommended, mainly for better image depth and realism. I.e., what most people describe as slightly toed in from being in the same plane.
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Yes, thank you;)
 
M

mraudioguru

Member
Joined 2014
Toeing of a Speaker

So, you guys have me confused :confused:

Here is a picture of toeing of a speaker.

Either NONE, TOE IN, or TOE OUT.
 

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AcoustatAnswerMan

AcoustatAnswerMan

Member
Joined 2011
Klimon said:
Just tried to measure bias voltage with my 10Mohm DMM using method 2, but sparks when touching the red terminal & cracking noise from the panels made me decide otherwise :eek: At the next attempt I'll disconnect the panels, but is method 2 intended for standard probes?

Simon, awed by the fierce power on that red terminal... :nod:

METHOD #2: (Alternate) Using a 10 megohm input impedance digital voltmeter, connect the ground (black) lead of the meter to chassis ground (at the solder lug attaching the white wire to the chassis). Apply power via the appropriate wall transformer, and allow the system to stabilize for several minutes. Connect the hot (red) lead of the meter to the red pin-plug terminal (where the panel connections are normally made). DO NOT CONNECT THIS TYPE OF METER TO LOCATION �5KV�. Adjust the trimmer potentiometer on the PC board until the probe reads approximately 75 volts DC. This reading will correspond to an actual 5000 volts, but the measurement is greatly reduced due to the voltage divider effect of the power supply and voltmeter.
Click to expand...


Any method used for measuring the bias voltage should be done with the panels disconnected. Yes, method #2 is for a standard DVM and probes, for those times when a proper HV probe is not available. Note also that the instructions specify to connect your meter first, then apply power. When finished, disconnect power and allow the supply to discharge for at least several minutes before disconnecting the probes.
 
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mraudioguru

Member
Joined 2014
Discopete said:
You should be sitting ahead of the toe in intersection. This puts you inside the sound stage instead of at the edge of it.
Click to expand...

So "you" are still toeing them in, just to a lesser degree? Okay, I get it now. You were never toeing them out, you were toeing them in, but not as far as some.

I have found that if you aim the center of the speaker at the arm rest of the listening chair, you get them to converge somewhere behind...
 
K

Klimon

Member
Joined 2005
AcoustatAnswerMan said:
Any method used for measuring the bias voltage should be done with the panels disconnected. Yes, method #2 is for a standard DVM and probes, for those times when a proper HV probe is not available. Note also that the instructions specify to connect your meter first, then apply power. When finished, disconnect power and allow the supply to discharge for at least several minutes before disconnecting the probes.
Click to expand...

Crystal clear, thanks!
 
D

Disco-Pete

Member
Joined 2009
Paid Member
mraudioguru said:
So "you" are still toeing them in, just to a lesser degree? Okay, I get it now. You were never toeing them out, you were toeing them in, but not as far as some.

I have found that if you aim the center of the speaker at the arm rest of the listening chair, you get them to converge somewhere behind...
Click to expand...
Excellent:up:. I'm still learning how to communicate.


Yes, but it's not a vague target. It still takes fine adjustment to get it right.
 
M

Mendel24

Member
Joined 2015
Discopete said:
Once you dial them in you'll notice just a 1/4" change either way puts them out of range. Equally critical is their being exactly on the same vertical plane.
Click to expand...

Thanks Discopete. I have had my Spectras for almost a decade now and have the freedom to place them anywhere I want in my man cave. Rarely a day goes by that I haven’t made a 1/4 inch move one way or the other so I know what you are saying:D. Pretty happy where I am now (with no socks!).
 
T

tyu

Member
Joined 2009
I have the Spectra 3,33,3300 same, only dif is the wired AC bias not the 33-330 wall wrat.
Yes with the Flat panels setup of all the Spectra speakers I can see you liking them with the grills off, down...With only that 3" wide high frec, the one panel has....but I don't like the sound of the added Spectra res for the mid an low output.
To my ears the old 1+1 with out the c-mod in the interfaces...the first Acoustat with crossover less interfaces...the one jim did to try copy the servos sound...

The spectra 11 are the only ones that dont sound bass heavy to me....
But that's me....as for full rang ESL...not much better
 
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