Hi Scott
So-called dBSPL measurements are norotiously difficult and even arguing how it should be measured. When I set up the fairfield measurement before the computer modelling, I use a Vifa XT25 Tweeter as my reference. How accurate it is, what frequency would you select and so on. Because I know that the XT25 Tweeter is extremely flat response (the flattest I have measured) and I set it up at 0.5M, mic right on axis, then I I look at the response between 2-4KHz and aim for 96dBSPL - this is 6dB more than if the same measurement was at one meter and the Tweeter is rated at 91dBSPL at one Meter.
I actually do all my measurements at 2 Metres rather than one, so I increase the output by +6dB, so the respoonse I get is 2 Metres, but the scale in dBSPL is one Meter.
The modelling sums all responses and the final frequency response is what you see:
If I was looking for an avereage from 100 Hertz to 10KHz, I would say 92dBSPL easily and maybe slightly more. What do you think?
I could justify dBSPL = 92.5dB ?
Cheers, Joe
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Well...I've decided...I'm going to build these. I just ordered the HDS tweeters...I don't buy anything on credit so I'll buy these drivers one pair at a time...Joe I sent you a PM...I'll be needing those wave guides ...can you give me the USD price in the PM so there is no mix up...thanks!
...can you give me the USD price in the PM so there is no mix up...thanks!Ok...so maybe someone who understands the math better than me can explain this. I am pretty sure I saw on Joe's website it says the Elsinore's are 8 ohm. My math has them at 4 ohm when all drivers are wired in. That's the four 8 ohm mid drivers wired in series and then parallel respectively, and the tweeter wired in parallel would bring the total back down to 4 ohm.
What am I missing?
What am I missing?
They are almost flat 6 Ohm, but they qualify nominally as 8 Ohm since by convention they don't drop below 5.6 Ohm. Why that figure, because it is 0.707 x 8 Ohm. So for a speaker to qualify as 4 Ohm, the impedance plot should not drop below 2.8 Ohm at any frequency and 16 Ohm speaker should not drop below 11.2 Ohm etc.
Everything!
The two Low-pass filters on the SB MidBass drivers increase the impedance (the two series inductors) so that the impedance is nearly 20 Ohm at the Crossover frequency. Here the series capacitor is 1.8uF and it has a reactance (a form of impedance) of 30 Ohm - this is because the series capacitance is so much smaller because we are using a Waveguide. Then add the nominal 8 Ohm impedance of the Tweeter and we have near 38 Ohm inpedance of the Tweeter's leg of the Crossover.
So you can relax. There is no commercially available loudspeaker which has as kind an impedance plot than the Elsinore Mk5 and Mk6. None in my 40 years plus experience comes anywhere near measuring like this:
ABOVE: ABSOLUTELY FLAT 6 OHM IMPEDANCE
Cheers, Joe
Thanks Joe...
Your excellent explanation was good enough to satisfy my question, without me understanding any of what you just said!
I figured the xover and other factors when brought to bear were the answer.
My new amp which is bridgeable says that when bridged it is effectively seeing half the load of the speaker.
My Nomex speakers measure at 6 ohms with a volt meter at the speaker terminals, which from what I understand, the amp sees 3 omhs...and the amp runs really hot!
Of course with the speaker terminals I could bi-amp.
But again...I only understand a very limited amount of all this.
Your excellent explanation was good enough to satisfy my question, without me understanding any of what you just said!
I figured the xover and other factors when brought to bear were the answer.
My new amp which is bridgeable says that when bridged it is effectively seeing half the load of the speaker.
My Nomex speakers measure at 6 ohms with a volt meter at the speaker terminals, which from what I understand, the amp sees 3 omhs...and the amp runs really hot!
Of course with the speaker terminals I could bi-amp.
But again...I only understand a very limited amount of all this.
i just wanted to give a shout-out about a previous post asking about the sensitivity of the MKV and Joe mentioned it should be around 92dB or so. I recently bought a 25 watt zero feedback stereo amp and wholly cow does it sound good! can't believe what an easy load this speaker is, just never ceases to please me!
this might be somewhat relevant to the current discussion regarding impedance, as these things are such an easy load that you have an amazing array of amp options.
cheers,
Scott
this might be somewhat relevant to the current discussion regarding impedance, as these things are such an easy load that you have an amazing array of amp options.
cheers,
Scott
I am not sure exactly what this means other than a bridged amplifier likely likes to see a higher load, for example 8 Ohm rather than 4 Ohm. So that is probably what it means.
What you are doing is measuring the DC resistance of the Voice Coil, the impedance of a speaker system is an AC measurement.
If the amplifier runs hot and if that is caused by the speakers (they should not have), then maybe the best thing is to do an impedance measurement and to see if something has gone wrong wiring up the speaker drivers and crossover. Or go over every aspect of the wiring and check all the values, maybe spot something wrong?
If everything is right, there is no reason for the amplifier to run hot, can you tell me whether it gets hot driving other speakers? The Elsinores are so easy to drive compared to other speakers, so if the other speakers don't causing heating and the Elsinores do, then something is not wired right.
Cheers, Joe
...these things are such an easy load that you have an amazing array of amp options.
cheers,
Scott
Correct !!!
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Sweet...thank you...yes I am in Florida.
No rush....my wife had a melt down when I bought these and the HDS tweeters....she's a cheap skate.
I will be buying components for this speaker in increments of the least "dog house" qualifiers possible!
I just bought one cap for the tweeter (1.8uf) because Parts Express only had one in stock...I got the Audyn True Copper Cap a $70 cap...for $50. A few years ago I set up a wholesale account with Parts Express so i get a deal on certain products!
I think this amp runs hot...I seem to remember reading something about it needing fans to cool it.
I'll try to find my information on that as well as what the Parasound manual says about it seeing half the load that the actual speaker is!
I'm not too worried about it...over time I've come to trust you Joe!
From the Parasound HCA 806a manual....
The HCA-806A is designed for a minimum 8 Ω nominal impedance for each speaker connected to
bridged channels 3+4 or 5+6. Use of lower impedance at high listening levels may cause overheating or
trigger one of the amplifier's protection circuits.
These restrictions result from the mathematics of the bridging circuitry. In the bridge mode each
channel of the amplifier functions for only the + or — half of the musical waveform. Thus, each
channel "sees" only half of the speaker’s impedance. Use of an 8 Ω speaker means that the load for
each channel is 4 Ω. For a 4 Ω speaker, the resulting load is only 2 Ω.
The HCA-806A is designed for a minimum 8 Ω nominal impedance for each speaker connected to
bridged channels 3+4 or 5+6. Use of lower impedance at high listening levels may cause overheating or
trigger one of the amplifier's protection circuits.
These restrictions result from the mathematics of the bridging circuitry. In the bridge mode each
channel of the amplifier functions for only the + or — half of the musical waveform. Thus, each
channel "sees" only half of the speaker’s impedance. Use of an 8 Ω speaker means that the load for
each channel is 4 Ω. For a 4 Ω speaker, the resulting load is only 2 Ω.
Would your amp perhaps be a Monarchy Zero Feedback amp? I purchased a Monarchy SM 70 Pro Class A zero feedback amp about 6 months ago and to say it is a good match for the Elsinore's would be an understatement. The clarity and dynamics are breath taking. On certain tracks the hairs on the back of your neck stand up!!! It would have to be the most generous 25W ever. I'm thinking of buying another SM 70 to run in dual monoblock mode.
i just wanted to give a shout-out about a previous post asking about the sensitivity of the MKV and Joe mentioned it should be around 92dB or so. I recently bought a 25 watt zero feedback stereo amp and wholly cow does it sound good! can't believe what an easy load this speaker is, just never ceases to please me!
this might be somewhat relevant to the current discussion regarding impedance, as these things are such an easy load that you have an amazing array of amp options.
cheers,
Scott
Any amp running in bridge mode will see half the impedance of that in normal mode. To understand this think of ohm's law. You have twice the voltage swing across the same load and each amp at opposite ends of that same load thus for an 8 ohm load each amp will effectively see 4 ohms. Some older amps had difficulty supplying enough current to do this properly but most modern amps can cope. They may run a bit hotter and this could be a problem with a Class A amp which is already creating quite a bit of heat. Also measuring a speakers DC resistance doesn't give it's actual impeadance. 6 Ohms DC would be about right for an 8 ohm speaker.
Thanks Joe...
Your excellent explanation was good enough to satisfy my question, without me understanding any of what you just said!
I figured the xover and other factors when brought to bear were the answer.
My new amp which is bridgeable says that when bridged it is effectively seeing half the load of the speaker.
My Nomex speakers measure at 6 ohms with a volt meter at the speaker terminals, which from what I understand, the amp sees 3 omhs...and the amp runs really hot!
Of course with the speaker terminals I could bi-amp.
But again...I only understand a very limited amount of all this.
... is capable of twice the voltage swing but that means that into the same nominal load it should produce twice the power. For example, to produce 100W into 8 Ohm we need to produce 80V peak-to-peak.
RMS(80V)=28.3V/8R = 100 Watt.
But if we bridge it, then in simple terms the amplifier will now be capable of swinging 160V peak-to-peak and the maths would then indicate we now have a 400W amplifier. In reality, it is the extra current (twice) drawn by the 8 Ohm load, this is the problem and to limit it to 200W we then have to increase the impedance to 16 Ohm.
RMS(160V)=56.6V/8R = 400 Watt.
Ouch!
This is the real reason why a non-bridged amplifier will cope well with 4 Ohm, but 4 Ohm now means the amplifier is asked to quadruple the power... help me out please!!
The load, the impedance, always stays the same, it is doubling the voltage swing that is the problem. But you have doubled both the voltage and the current and that is 4x.
Clear as mud?
Cheers, Joe
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