The circuits do indeed have different topologies. That is what makes them different. If they sound different OF COURSE the differences in circuit topology are the reason. They all operate in the same environment (supply voltage, temperature, airflow, input signal, output load) so that's not the reason for sonic differences. Okay, if that's not it, then what's left? The circuit topologies are different, indisputably. An obvious fact that anyone who looks at the schematics can instantly see. Drawing a red circle around the obvious is not an act of trailblazing insight.
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From the FIRSTWATT website, THD for the M2 is listed as 0.050%, noise is 500uV with gain at 15dB.
My M2X ripple measured from each diode bridge = 0.150 vac
Ripple measured at each rail = 0.050 vac (50 mV).
Since I built an F5 power supply, I checked in the F5 article and found ripple as 0.070 vac (70 mV).
Distortion analysis for Tucson IPS, 1 watt @ 4 ohms.
Saturday = Austin
Sunday = Ishikawa
My M2X ripple measured from each diode bridge = 0.150 vac
Ripple measured at each rail = 0.050 vac (50 mV).
Since I built an F5 power supply, I checked in the F5 article and found ripple as 0.070 vac (70 mV).
Distortion analysis for Tucson IPS, 1 watt @ 4 ohms.
Saturday = Austin
Sunday = Ishikawa
Attachments
I have shielded Edcor with both copper tape and mu-metal foil and I am building the PSU's for M2X in the moment. The goal is to have very little 50/100 Hz at the amp output. Will see how all my efforts turns out. Need to make a power amp to Focusrite interface so I can measure the distortion. First try will be with Tucson input boards with OPA604 opamp. Seems to be an old classic FET input opamp.
It is interesting to have a look inside the original FW M2:
6moons audio reviews: FirstWatt M2
….I wonder who made the shielding case for the Edcor…..
6moons audio reviews: FirstWatt M2
….I wonder who made the shielding case for the Edcor…..
Were you going to try the SLB power supply? It is the best Class A PSU I have ever used - it stops mains hum in its tracks. It has a bunch of extra ground spade terminals on the main star hub ground plane. Makes going to true star topology for grounding very easy. Also has built in NTC and bypass cap for connection to chassis/earth ground.
No....my approach is more "classic". I build mono blocks. The toroid has a magnetic shield and as I use 5U Deluxe x2 I have a lot of space inside so toroid can be placed far away from Edcor. I use DiyAudio store PSU board as basis using Cree Schottky diodes. Then I have extra LC stages using 2.5 mH / 10A DC filter chokes together with Jensen 4-pole caps as the last filtering. The simulation also say around 1 mV ripple at 2A current. Will post some pictures when I am almost there…..
zman01 - Yes, I am listening to each IPS, however it's in the shop area not the primary listening room. I have Boston Acoustics bookshelf speakers in the shop.
My main intent with these measurements is to be able to adjust RV1 on the Ishikawa board. If Austin IPS has the same even 2nd and 3rd distortion, then I'll adjust RV1 that way. So far, Mountain View and Tucson have the same 2nd and 3rd characteristics, I hope Austin is the "three times a charm".
My main intent with these measurements is to be able to adjust RV1 on the Ishikawa board. If Austin IPS has the same even 2nd and 3rd distortion, then I'll adjust RV1 that way. So far, Mountain View and Tucson have the same 2nd and 3rd characteristics, I hope Austin is the "three times a charm".
I think I may remove the ground wires from each shield and see how that measures. I agree, I'd like to get rid of the 60 & 120 hz noise, since the ripple measurement is better than what Nelson listed on the F5 power supply, I'm thinking ground loop issue.
Using REW and performing the measurements like xrk971 taught us, at least I have a tool to measure the 60 120 hz noise.
I was going to make a list of all the possible ground issues and then try them one at a time until......I go nuts!
Using REW and performing the measurements like xrk971 taught us, at least I have a tool to measure the 60 120 hz noise.
I was going to make a list of all the possible ground issues and then try them one at a time until......I go nuts!