Audio Design Guide 2014 Power Follower

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I posted this in Solid State Forum first, but after 150 views, no one has any idea, so I'm requesting help from the might Pass Labs forum. Also, I directly emailed and contacted the author on one of his threads regarding this very design, but no answer.

It's a MOSFET Power Follower so it's not alien to the PL guys here.
So, any help or advise would be appreciated.

Original post:

I have some questions about the Andrea Ciuffoli 2014 Power Follower.

The new 2014 schematic and 2014 board do not include the output cap.
Is the output section built the same way as the older schematic?

I assume the positive speaker connection, if built like the '99 version, connects to the positive side of the output cap. This correct?

Is the 1k resistor needed across the speaker on the 2014 version

The 2014 schematic shows R10 and R11. Are both needed?

The '99 Power Follower Schematic is not label with a date. The 2014 schematic is labeled.



Thanks,

Vince
 

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Is this a rhetorical question or are you concerned by it being too much?
New version is fixed by R1. Old version can be switched.
That's what the man said. Is that too much?

Is it any crazier than 2.5A for the MoFo? I don't know. MoFo sounds great at 2.5A :D
 
Last edited:
... any help ...

Is the output section built the same way as the older schematic? Yes, but no provision to alter bias.

I assume the positive speaker connection, if built like the '99 version, connects to the positive side of the output cap. This correct? Depends on what you want. I think there should be no problem to connect Negative polarity of speaker to positive leg of output cap if you prefer negative H2 phase.

Is the 1k resistor needed across the speaker on the 2014 version. Yes, to avoid unwanted dc potential build up on output terminal due to output capacitor.

The 2014 schematic shows R10 and R11. Are both needed? No, choose one.
 
Official Court Jester
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too much

two trimpots on schematic - just provison to mount two different physical styles - see pcb - mount one you prefer to fiddle with

resistor across speaker is bleeder - to drain outout cap and prevent plop! when connecting speaker

output node is at negative potential , ref. to gnd , so output cap must have negative pole at output node , positive to speaker

edit: indra was faster
 
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I prefer MoFo .....

certainly livelier , due to principle

You built both or you just looking at the schematics?

Not worried because only paid for the boards. Rest of parts and case are spares. Got an $100 gift card at work and used Amazon to buy the rest I didn't have.

Not afraid to give this interesting circuit a try. ;)
How many power amps can be built with one small filter cap? :rofl:

I have no idea how it will sound. Just interested in Power Follower sound right now. Maybe I'll dump this one and build a couple of F4 monos and live happily ever after. who knows :confused:

Thanks for the help! :D

Vince
 
Official Court Jester
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You built both or you just looking at the schematics?

....

built , heard and know difference between inductive loading and CCS

in this case , with KISS approach , inductive is better to my ears

besides that , less heat for same power , which is important ...... after some time , when you fed enough appetite for simplest overkill

all in all , personal preference .......
 
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I had a chassis and 30v 8A transformer from my failed attempt at a 25w Schade feedback amp. The PF 2014 amp can run from the same voltage, so I built it and after some troubleshooting with the designer Andrea Ciuffoli (found a bad BD139 bjt) its up and running.

I built it just to hear it, to try something different in the power follower vein.
Its as fine amp in it's own right. It's very quiet and dynamic as well.
Think I will keep this amp for a while. :)

Up next is the F4...:D

Thanks,

V.
 
I have recently built two ADG designs. Firstly, the Inpol/Mofo SE Class A version 3, which is similar to the big MoFo designed by Michael Rothacher. Secondly, the Power Follower 2021 version. Both designs use valve (tube) voltage amplification stage and SMPS for the current amplifier stage. Building is straightforward as PCB's are used for both stages. IMO they both sound very good. The Power Follower may have a slight edge in terms of detail and clarity, but the Inpol/Mofo has more grunt, consistent with its more efficient design. I found both to provide adequate volume in my listening room (small to average sized living room) with 88dB sensitivity speakers. I subsequently "discovered" SIT's and unfortunately, there's no going back!
Hope this helps.