I’ve had a quote from a transformer maker near me for a pair of custom chokes. The specs are as follows:
100mH, 3.5A, 0.7 ohms Frame mounted choke.
Based on the specs of the recommended chokes these would seem to be just the job; but Is there any other spec I should verify before ordering ?
100mH, 3.5A, 0.7 ohms Frame mounted choke.
Based on the specs of the recommended chokes these would seem to be just the job; but Is there any other spec I should verify before ordering ?
Is a copper band essential or just nice to have ? Do the Hammond ones have that?
Speakers are 96db/1W. iFi pre amp with 18db gain.
LM3875 integrated chip amp and iFi EL84 tube amp was compared to the MoFo. Ive used the MoFo all week and it effectively replaced my chip amp. one surprise is the added extension the MoFo portrays in the bass. it does seem to reach deeper then the chip amp.
The MoFo have the chip amp beat everywhere apart, maybe, speed. The tube amp is still a bit superior, maybe, but i have to admit after a week, im not even certain anymore. Both the tube amp and the MoFo are extremely good and I can use without reservation. The MoFo musicality really won me over this week and going back to the chip amp is impossible. very happy! what a deal!
Is there really much better in Pass lab amps? I dont actually need more power!
im already quite amazed by the SQ of the MoFo. what would be a clear upgrade path from here?
LM3875 integrated chip amp and iFi EL84 tube amp was compared to the MoFo. Ive used the MoFo all week and it effectively replaced my chip amp. one surprise is the added extension the MoFo portrays in the bass. it does seem to reach deeper then the chip amp.
The MoFo have the chip amp beat everywhere apart, maybe, speed. The tube amp is still a bit superior, maybe, but i have to admit after a week, im not even certain anymore. Both the tube amp and the MoFo are extremely good and I can use without reservation. The MoFo musicality really won me over this week and going back to the chip amp is impossible. very happy! what a deal!
Is there really much better in Pass lab amps? I dont actually need more power!
im already quite amazed by the SQ of the MoFo. what would be a clear upgrade path from here?
I am thinking of building the Mofo but with some alteration.
1) for gain I am thinking of a 600:60k 10:1 ratio transformer. I might put a simple transistor with constant current source as a buffer. I want to use this without looking building an external preamp that will go out 10V+. I believe I would probably need to change the input resistors. Thinking of changing it to about 200K for the bias resistor. Do you guys think it will be okay? I think if I were to use transformer the input resistor is redundant.
2) I am planning on replacing the irfp250 with FQP50N060L, it seems to have better gain at about 1 to 2 amps. Any change I should do to the resistor at the gate?
1) for gain I am thinking of a 600:60k 10:1 ratio transformer. I might put a simple transistor with constant current source as a buffer. I want to use this without looking building an external preamp that will go out 10V+. I believe I would probably need to change the input resistors. Thinking of changing it to about 200K for the bias resistor. Do you guys think it will be okay? I think if I were to use transformer the input resistor is redundant.
2) I am planning on replacing the irfp250 with FQP50N060L, it seems to have better gain at about 1 to 2 amps. Any change I should do to the resistor at the gate?
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Hi,
I am picking up something from Aliexpress. I think should be doable as long as the input impedance is very high. 1 meg would be good but I am not sure if input impedance that high is achievable....
I have my MoFo driven by an AKSA-Lender 40v pre-amp, which is driven by a battery-driven sound source (my phone). I don't have another DIY setup (yet!) for comparison. It sounds great.
The Big Deal with this amplifier is the parts count. I think it was @Zen Mod who replied to my request for a pair of PCBs that the MoFo was so simple I could consider a "dead bug" build without the PCB. (It was my very first build; I felt I needed the "guardrails"). Bolt the IRFP250 to the heatsink, and everything else would hang off those beefy TO-247 leads. Well, maybe not the inductor.
My build has Edcor chokes, Infineon transistors, Nichicon cap, Vishay resistors, ASUS power supplies; no need to skimp on parts, but also no need for gold plate. That's most of the charm!
Given the low cost in the BOM, I feel like everyone should spend the ridiculously short amount of time assembling the two channels as originally specified. If your pre-amp can actually swing to 40v, you'll get a great sounding system in short order. Come back and tell us how it sounds. THEN start fiddling with modifications.
And then come back and tell us how the mods sound to you!
Kind regards,
Drew
The Big Deal with this amplifier is the parts count. I think it was @Zen Mod who replied to my request for a pair of PCBs that the MoFo was so simple I could consider a "dead bug" build without the PCB. (It was my very first build; I felt I needed the "guardrails"). Bolt the IRFP250 to the heatsink, and everything else would hang off those beefy TO-247 leads. Well, maybe not the inductor.
My build has Edcor chokes, Infineon transistors, Nichicon cap, Vishay resistors, ASUS power supplies; no need to skimp on parts, but also no need for gold plate. That's most of the charm!
Given the low cost in the BOM, I feel like everyone should spend the ridiculously short amount of time assembling the two channels as originally specified. If your pre-amp can actually swing to 40v, you'll get a great sounding system in short order. Come back and tell us how it sounds. THEN start fiddling with modifications.
And then come back and tell us how the mods sound to you!
Kind regards,
Drew
Truthfully, writing my reply has inspired me to build anew without PCB. Will post when finished, of course.No Porn, No Glory
show us your dead bugz, then bask in shiny rays of Celebrity
But I must finish my M2X first.
And my ACA Mini.
And my DAC.
sigh
@MR; It’s 5 years since you posted this. What are your thoughts now about the puck vs the 250 ?Well, the distortion was lower due mainly to the much higher bias, and the output impedance is a little lower. I haven't spent any time listening to it yet.
It's really just a case of me taking things to the extreme out of morbid curiosity and the pure fun of it. Whether it sounds better or not wasn't really the priority.
Actually after thinking it through, the main reason why I want a transformer is because the input voltage swing needs to be almost twice as high as the supply voltage to be able to fully drive this. And it is obvious that a normal preamp will not be able to do this. Hence the transformer. However, a new thought just came to my head to use an pre amplifier that is inductor powered too. Similar to the L'amp inducted but everything a lot smaller though. Maybe might use a BJT on that. Might use 100mH 70mA inductor for this. Gain will be determined by the input bias resistor of Mofo...