James B. Lansing M2 Master Reference Monitor has been ordered and is on its way here to beautiful, sunny down town Cool, CA.
Why? High dynamic range without distortion nor compression, very low distortion, controlled directivity, wide and flat freq response.... to name a few.
[ I haven't told Lisa the cost, yet. She pays the bills. Should I let her be surprised at the CC balance and find out that way?]
here's to living dangerously.
THx- RNMarsh
May you enjoy them for many years to come, I still remember how I felt at the top of the world when I got my currrent speakers because they were the best I had heard in my life below the $15k mark, I loved thgem then, and I still love them today, but I think that if I were to change them, the new ones would probably be by JBL too. 4312 monitors of course, first love is never forgotten, despite the fact that they are not as low reaching as one might expect.
Exactly what I told Milan Karan (Karan Acoustics – Manufacturer of High-End Audio) when he went about designing his killer speakers, all using top dollar JBL drivers. He makes excellent amps and preamps, but that speaker (each weighing in at around 100 kg, or app. 220 lbs) ended up sounding like a sound reinforcement unit, decidedly less than the sum of parts.
I told him to forget it and stick to electronics because that's where he was good.
You are welcome.
All the equalisation, the filters, the x-over and the delay settings that are shown in the linked screenshots, are readily implementable through the graphic interface of the miniDSP plug-ins.
In case you have the miniDSP 2x4 kit, I can set up a JBL_M2.xml file for you with all those settings.
If you want to, tell me which plug-in you are using and I can do it for any of the '2Way Advanced', the '2Way Advanced 2.1' or the '4Way Advanced' plug-ins.
George
REALLY !!! That is AMAZING and more than I could hope for. Thank you. Thank you. Thank you.
I have the 2x4 HD. I havent any plug-in, yet. Probably the 2 way advanced..... hopefully wont need a sub.
Thank you very much..... Richard
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If you want to know about the M2 DSP engine just call Charles Sprinkle. He is the source.
https://www.youtube.com/watch?v=WUuMQY9yBOI
https://www.youtube.com/watch?v=WUuMQY9yBOI
Yes Papa. One issue I have been playing with is CRC filters. I suspect they are a bit more effective as CR2C with the total capacitance remaining the same. A slight difference than what you showed on that F5 variant. Any practical experience with the issue is welcome.
I might actually build one as a bit back I noticed the distortion spectra matched that of the resistors used in the feedback network. You mentioned it has active device limits and as it is your baby you are most likely right. But I am curious as to how much the feedback network does contribute. Then I can also see a bit about power supply filtering differences.
I might actually build one as a bit back I noticed the distortion spectra matched that of the resistors used in the feedback network. You mentioned it has active device limits and as it is your baby you are most likely right. But I am curious as to how much the feedback network does contribute. Then I can also see a bit about power supply filtering differences.
Charles is a good guy. He got tired of working for the consumer group and is now with JBL Pro I understand.
He has developed a program that allows a pretty decent prediction of loudspeaker behavior, especially including off-axis response. This is making loudspeaker design closer and closer to a predictable pursuit, not that that will change too many minds among the high-enders.
He is also a firm believer in the benefits of sound money. If he still has gold holdings he should be pleased at the recent uptick.
He has developed a program that allows a pretty decent prediction of loudspeaker behavior, especially including off-axis response. This is making loudspeaker design closer and closer to a predictable pursuit, not that that will change too many minds among the high-enders.
He is also a firm believer in the benefits of sound money. If he still has gold holdings he should be pleased at the recent uptick.
So, other than adding .4nV/rtHz to each jfet, and losing 30%-50% of the available transconductance, what's the point of placing 10ohm in series with each source?
Don't tell me the story about current hogging, jfets don't, even if Idss is like 2:1 distributed.
You make an interesting point Waly. I guess that I could remove or significantly reduce the 10 ohm resistor and get a total of 2.5 ohms less noise. However, in the initial design I did not exactly know the source of the jfets, so I wanted a little control over each one, and a convenient current measuring point for each device.
Operating at 0 bias is questionable, although it certainly works.
The original single input (not balanced) Vendetta, used a 10 ohm, 10 turn, wirewound pot that was used for both bias and 2'nd harmonic nulling. This design only uses the 10 ohm resistors for bias, so they could be removed so long as strict Idss matching is kept.
Operating at 0 bias is questionable, although it certainly works.
The original single input (not balanced) Vendetta, used a 10 ohm, 10 turn, wirewound pot that was used for both bias and 2'nd harmonic nulling. This design only uses the 10 ohm resistors for bias, so they could be removed so long as strict Idss matching is kept.
REALLY !!! That is AMAZING and more than I could hope for. Thank you. Thank you. Thank you.
I have the 2x4 HD. I havent any plug-in, yet. Probably the 2 way advanced..... hopefully wont need a sub.
Thank you very much..... Richard
I just finished download/installing the HD-1 plug-in software. 2-way advanced is needed. What is next?
THx-RNMarsh
Make that 1.25 ohm, since from an AC perspective the n and p halves are exactly in parallel. Without those resistors you could likely get along with only 3 pairs, and save your precious antiquities. BTW, those devices are likely two factory matched 2SK170/SJ74, mounted in a metallic casing. Nothin like the monolithic 2SK389/SJ109. Anybody with a decent stock of LS devices and a bundle of cable ties could produce these devices, perhaps even better matched than the originals.
I just ran across a 10yr old thread where folks were wondering why a condenser mic lost gain when they put a 40pF FET in for a 5pF one then a conversation started around sonic differences when flipping the source and drain on an SK170 (I posted its die photo here, absolutely symmetric). With rampant cluelessness I've learned to expect anything.
Waly, you got that part right, but remember this is a differential input so you get 1.25 ohms X 2 because the input devices are in series and get 2.5 ohms added input noise, still some significant contribution.
The input pairs for my BEST design are the 2SK146-J73, that I personally supplied Constellation and they are equivalent to 2 X 2SK147 for each individual device, so that gives me a 3dB advantage over the 2SK170-74 all else being equal.
The 'cheaper' version of the Constellation uses just multiples of the 2SK170-J74 so it is a few dB noisier. In this case, the 10 ohm resistor is just about optimum, considering the potential randomness of the selection of the 2SK170-J74 devices in production, but for the more costly version, I agree that 5 ohms could be used, or even a single 5 ohm resistor for the entire array of 16 devices as a single bias resistor (CM noise contribution only) to get even further noise reduction, perhaps 5 ohms equivalent noise or 0.3nV/rt Hz
The input pairs for my BEST design are the 2SK146-J73, that I personally supplied Constellation and they are equivalent to 2 X 2SK147 for each individual device, so that gives me a 3dB advantage over the 2SK170-74 all else being equal.
The 'cheaper' version of the Constellation uses just multiples of the 2SK170-J74 so it is a few dB noisier. In this case, the 10 ohm resistor is just about optimum, considering the potential randomness of the selection of the 2SK170-J74 devices in production, but for the more costly version, I agree that 5 ohms could be used, or even a single 5 ohm resistor for the entire array of 16 devices as a single bias resistor (CM noise contribution only) to get even further noise reduction, perhaps 5 ohms equivalent noise or 0.3nV/rt Hz
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Yes. I suppose it is time for a comprehensive article on noise matching for different source impedances. I did a paper ages ago addressing the topic for a primarily capacitative source with a specified leakage current. Having thought I understood the problem going in, I discovered it was considerably more intricate and involved solving cubics.
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