Cool, Mini MoFo
Transformer?
Well, audio transformers are expensive, but car electric systems have a lot of ignition and electronic injection interference, so is good to have a isolation from the auto radio and amplifier. And the plus, the trafo can transform the RCA level to MoFo level (if is drive capable), or transform the bridge output from output power IC to single-ended for MoFo output MOSFET
Most car amplifiers have a differential (subtracting) OPAMP for ignoring commom mode signals and so ignore ground induced interferences. Others use SMPS with insulation (power supply trafo with primary-secondary; not boost supply)
Andy, i have simmed and I am now building a preamp/active crossover that's feeding a mofo for tweeter and other amps (pass/firstwatt inspired thingies) for mid-bass 60-700hz/sub-bass <60hz. I'm using 01a valves as gain stage- at about 8 in system gain will give me 16vrms to feed the mosfet as I get 2vrms out of my dacs and riaa. -> Peak voltage into mosfet about 22.6v and factor in dc-resistance from the choke it would suit a 24v power supply . That combination could end up around 25-30W@8ohm as in the article
In my case I'm using 16ohm faital pro 1,4" compression drivers which gets too loud already with my 45 amp at a blazing 1200mW so i will use 19v laptop chargers as PSU. Only 1.3A bias due to 16ohm driver Net swing voltage in that combo 17.5v peak do around 10w which is really too much but first tries are very promising. I could really use 12v PSU's but i had a whole carton of nos dell 19V@4.5A (used one per channel which might be overkill) supplies so i figured "why not".
//Niklas
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Actually, when I built my balanced F4s I built a Pumpkin/Shunty and Stuart’s Impasse. I settled on the Impasse because it offered a more laid back presentation. However I did enjoy the Pumpkins fast presentation. I have had both pieces slated for a freshening up while I have been using my tube amps, and playing with digital toys. It is compelling to mate the Pumpkin with the mofo, what do you think would be the best way to merge the two?
Bill
Bill
While I realize it’s a stupid reason to build an amp but hey any reason is a good reason. If I cut this in half I wonder if it would it dissipate enough heat for a pair of mofos, they are just unconventional enough to join my odd man collection. Strange when I post the picture it keeps inverting it, the gremlins are at play today!
Bill
Bill
Attachments
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just put some cables in between
pins 1 and 2 of XLR are take out points for RCA output
I like them raw, I will order the circuit board but in the end I really like the Look of nude with flying wires. I will cut the heat sink in half and give it a try, I have some ordinary extrusion that would work if they get to hot. Will have to pair it with a good economical OB would look really cool. Kind of a wine cheese pairing thing. Finally built my Frugal horns and paired them with a pair of OPC wire 16 watt LPUHP mono-block amps nice system.
Bill
Bill
Efficiency question
This could well be a dumb question - I couldn't find mention of it in this thread.
I was just looking at the Aleph patent and noticed a claimed doubling of efficiency. Could that apply here?
Has anyone considered adding an Aleph current source to a MoFo? Sure, it will increase complexity a bit.
The hope is that it will reduce the cost of the heat sinks, and possibly the choke (lower average current). Bonus if it improves distortion.
This could well be a dumb question - I couldn't find mention of it in this thread.
I was just looking at the Aleph patent and noticed a claimed doubling of efficiency. Could that apply here?
Has anyone considered adding an Aleph current source to a MoFo? Sure, it will increase complexity a bit.
The hope is that it will reduce the cost of the heat sinks, and possibly the choke (lower average current). Bonus if it improves distortion.
With a current source, you will need to increase the power supply voltage, as the current source also drops voltage. So double the supply voltage. The current source will also dissipate heat, so double the heat sink capacity.
However, the big factor is that the MoFo is a follower, with no voltage gain. Aleph current sources are used with voltage gain common source amplifiers. I don't believe a follower amplifier can take advantage of the capabilities of an Aleph current source.
However, the big factor is that the MoFo is a follower, with no voltage gain. Aleph current sources are used with voltage gain common source amplifiers. I don't believe a follower amplifier can take advantage of the capabilities of an Aleph current source.
I'm working on a MoFo project that I'll use to drive a 'full-range' speaker in an open baffe speaker (Pass SLOB). I plan to roll-off the full-range unit at around 180Hz so the plan is to adapt the MoFo so that it doesn't need to handle the bass frequencies.
The thinking is to use a cap of about 15nF for C1 (the input cap) so the input CR filter has the right sort of corner frequency and to use a 7mH inductor for L1 (see post #1681 on page #169). How does that look?
Assuming I've got that about right, any thoughts/recommendations for a suitable inductor?
The thinking is to use a cap of about 15nF for C1 (the input cap) so the input CR filter has the right sort of corner frequency and to use a 7mH inductor for L1 (see post #1681 on page #169). How does that look?
Assuming I've got that about right, any thoughts/recommendations for a suitable inductor?
Hello Billjust put some cables in between
pins 1 and 2 of XLR are take out points for RCA output
You need connect XLR pins 1 with 3 as well for proper RCA output
Edit: you can make DIY cable with picture two
Attachments
Hey guys, I have a few questions about specific uses of this amp. I have taken a college level circuit analysis course and I'm willing to do some research on my own if pointed in the right direction.
My questions are:
Can I run 2 big MOFO's (meaning a Hammond 193V Choke and 24V at 2.5 amps) in parallel into a 4 ohm load like a magnepan without any issues? I think I read that the limiting factor would be mosfet heat dissipation and supply current but please let me know.
I am looking for a suitable tube preamp (for voltage gain). In the spirit of DIY I saw the bottlehead Moreplay and was wondering if this would be suitable. Its cap coupled and has a gain of 9DB, although they are working on a CCS load for it which might impact the gain.
Best,
tapehissmakesmehappy
My questions are:
Can I run 2 big MOFO's (meaning a Hammond 193V Choke and 24V at 2.5 amps) in parallel into a 4 ohm load like a magnepan without any issues? I think I read that the limiting factor would be mosfet heat dissipation and supply current but please let me know.
I am looking for a suitable tube preamp (for voltage gain). In the spirit of DIY I saw the bottlehead Moreplay and was wondering if this would be suitable. Its cap coupled and has a gain of 9DB, although they are working on a CCS load for it which might impact the gain.
Best,
tapehissmakesmehappy