Hafler dh110 mods anyone?

[amp-guy]

O.K. so we have some threads on modding Hafler power amps, so somehow me thinks there must be out there a few that are using a Hafler preamp as well.
I think the DH110 arguably has the most potential (it is discrete no chips) it has the most potential of couse the real reason is that I happen to have one.
So as a start I have on a seperate little board beefed up the ridiculously small power supply caps. And on another small board mounted up a pair of polypro caps to replace the onboard electrolytic output coupling caps, pretty basic mods so far .
so now to actual circuit mods Iam thinking maybe replacing the darlington connected outputs with a pair of mosfets. iam primarily concentraing on the line stage because that is all I use - no analog playback gear to use .
any thoughts or experiences with the dh110
Now where is that schematic oh rats have to post it later.

[jameshillj]

Found it!

What about a simple buffer o/p with maybe k170/j74 as per JC?

I generally like the results from Shunt regs PSUs - there's a Group Buy pcb coming together (the B1 + Salas shunt) that'll fit well.

I recently got some of those PETP caps over from the Ukraine as an alternative to some of the PPs I generally use - quite remarkable. I got mainly the K73-16s 63volt ones for my F3 and Xovers to see just how good they were.
Then ordered some of the K75-10 and K40-9s (on the way) to widen the choices. I remember that if you can get enough volts across these animals, they function very well. We'll see.

[amp-guy]

Ah yeah you are thinking along the same lines
the JC2 with 2sk's may fit right into the board layout.
also the rca jacks are prone to corrrode giving contact rectification resulting in awfull sound, I replaced mine with gold ones seems like they came from Mouser electronics, they were a direct solder in replacement. Not sure if they still sell them though .
Actually with these simple changes you get a pretty decent preamp.
with all the DH220's and dh500's out there Iam puzzled why there seems to be so few DH110 preamps.
somewhere I have a redrawn schematic that I did with Circuitmaker 200 pro I will see if I can find it and post it.

[jameshillj]

Thanks for that - must push this one up on the list.

[ichiban]

Originally Posted by amp-guy

somewhere I have a redrawn schematic that I did with Circuitmaker 200 pro I will see if I can find it and post it.

Is your redrawn schematic with the JFETinput mod? Would like a peek at it!

[smallies]

I wish I knew what caps you put in there seeing as it's a Mouser saturday night for me. Chris