35 year Hafler veteran...
Brain tickle - on this amplifier porn thread.
I am a third of the way, reading this entire thread,
having to take breaks so my head does not
explode... fall clean of my shoulders.
GREAT WORK EVERYBODY!!! Fabulous.
I am a 35 year Hafler veteran, builder
and extensive hot rodder...
I have been accused of absolute Hafler bias,
IT IS TRUE, I have worked to finesse every
bit out of "a venerable amplifier legacy".
I have a long standing relationship with John Hillig,
have learned one ~hell of a lot~ about amplifier design
and general electronics, mostly power supply designs.
I have over 100 Hafler builds (all modified, made correct
I cannot believe I have not seen this thread before.
Currently updating 4 PA-4 board sets, of various amps,
which I do struggle calling Hafler amps, at this point.
Brain tickle - on this amplifier porn thread.
I am a third of the way, reading this entire thread,
having to take breaks so my head does not
explode... fall clean of my shoulders.
GREAT WORK EVERYBODY!!! Fabulous.
I am a 35 year Hafler veteran, builder
and extensive hot rodder...
I have been accused of absolute Hafler bias,
IT IS TRUE, I have worked to finesse every
bit out of "a venerable amplifier legacy".
I have a long standing relationship with John Hillig,
have learned one ~hell of a lot~ about amplifier design
and general electronics, mostly power supply designs.
I have over 100 Hafler builds (all modified, made correct
I cannot believe I have not seen this thread before.
Currently updating 4 PA-4 board sets, of various amps,
which I do struggle calling Hafler amps, at this point.
Attachments
Brain tickle - on this amplifier porn thread.
I am a third of the way, reading this entire thread,
having to take breaks so my head does not
explode... fall clean of my shoulders.
GREAT WORK EVERYBODY!!! Fabulous.
I am a 35 year Hafler veteran, builder
and extensive hot rodder...
I have been accused of absolute Hafler bias,
IT IS TRUE, I have worked to finesse every
bit out of "a venerable amplifier legacy".
I have a long standing relationship with John Hillig,
have learned one ~hell of a lot~ about amplifier design
and general electronics, mostly power supply designs.
I have over 100 Hafler builds (all modified, made correct
I cannot believe I have not seen this thread before.
Currently updating 4 PA-4 board sets, of various amps,
which I do struggle calling Hafler amps, at this point.
Welcome to the thread!
Your picture shows a good integration of a different power supply.
What are the pcb used as they not appear to be Hafler original... also any reason why you appear to have used Elna Silmic II caps on one channel and Nichicon on other channel...
Fab
Many amps, all evolving to same...
Thank you fab... I am half way through reworking 'that' MC220 amp modeling it *exactly* after the P230/XL280 chassis, 6 output version. The Silmics are (were on the stock, 2013-14?) Musical Concepts PA-4 boards on the left, and newer parts being installed, in process on the right.
The power supply shown, the 4 pole Jensen caps are the best that I have heard on these amps. I mentioned, but did not elaborate, I was a Musical Concepts reseller/dealer years ago, 80s-90s, my starving artist days...
The past 2 years, I have been focused on retiring, selling a long term home, relocating and moving many boxes; ..finally.. the past 2 months has been reworking many pieces of gear.
I have been 'power listening' with multiples of (3 Hafler 110) pre-amps and 7 different amps are being reworked. I had been voicing attributes to the current build(s) bass weight and extension... sheer slam. Well it turns out the current Hafler DH110 pre-amp ~ with all Nichicon MUSE caps throughout is what I was experiencing through the 220 ~ 230/280 ~ 500 model amps (shown)
The 2 closest amps are updated the back two (both Jensen capped) beasts are still stock Musical Concepts stuffed boards. I shot this picture to show a buddy what i have been doing, with focus more on the power supplies, as such. The DH200 on the lower right was an effort to try and duplicate the beauty of the $$$ Jensen capped P/S. That Hafler 200 is among my favorite amps... another story...
Thank you fab... I am half way through reworking 'that' MC220 amp modeling it *exactly* after the P230/XL280 chassis, 6 output version. The Silmics are (were on the stock, 2013-14?) Musical Concepts PA-4 boards on the left, and newer parts being installed, in process on the right.
The power supply shown, the 4 pole Jensen caps are the best that I have heard on these amps. I mentioned, but did not elaborate, I was a Musical Concepts reseller/dealer years ago, 80s-90s, my starving artist days...
The past 2 years, I have been focused on retiring, selling a long term home, relocating and moving many boxes; ..finally.. the past 2 months has been reworking many pieces of gear.
I have been 'power listening' with multiples of (3 Hafler 110) pre-amps and 7 different amps are being reworked. I had been voicing attributes to the current build(s) bass weight and extension... sheer slam. Well it turns out the current Hafler DH110 pre-amp ~ with all Nichicon MUSE caps throughout is what I was experiencing through the 220 ~ 230/280 ~ 500 model amps (shown)
The 2 closest amps are updated the back two (both Jensen capped) beasts are still stock Musical Concepts stuffed boards. I shot this picture to show a buddy what i have been doing, with focus more on the power supplies, as such. The DH200 on the lower right was an effort to try and duplicate the beauty of the $$$ Jensen capped P/S. That Hafler 200 is among my favorite amps... another story...
Why do you replace the power transformer? I find the OEM just fine. I took two DH220's and re-packaged into a three channel unit with dual power supplies paralleled. So we have three amp channels across two power supplies. I have a small microcontroller monitoring both supplies, temp, and DC offset. It reports status via RS232.
Then I did the same with two DH120s. I use them as LCR triamps. The DH220's are woofer, the 120's mids and I have a 20wx3 class a for the tweeters.
I kept the OEM Hafler driver boards. I think they are fine. I know there are a few highly regarded replacement boards but I tend to trust Hafler engineering.
I'll post some pics next week.
why i replace the power transformer?
1)space saving ,to install big electrolitics,softstart-protection boards
2)toroid is 630VA , biger than the original unit with indipendant secondaries for left,right ch
3)secondaries is chosen to 44+44 much lower than original unit for reliability reasons(k134-j49 max drain-sourse voltage is 140v so for a pushpull amp max theoriticaly voltage is 70v
practicaly a litle bit lower.I have seen PA amp with k135-j50 working at more than 90v without problem!,all haflers also!and never saw a failed MOSFET! Such a robust devices!,but nowdays are very hard to find so protecting them is a must!)
so my target goal is around 125wrms
4)heatsinks are very small for desapating continious 60+ Watts when qc is chosen @0,4A
and i think optimal for 45W in my case!
keeping OEM hafler boards is a very good choise(Symetrical design,JFET diferential input(xl280)(BJT for DH2XX),designed by the amp guru E.B.!) better than crap like musical concepts (http://www.musicaldesign.com/PA3E_INSA.pdf) and other e-bay boards!
ill try to go for something even better designing new drivers with best performance in mind,working on it allready for 3 months now
thanks in advance
your pics are very wellcomed!
1)space saving ,to install big electrolitics,softstart-protection boards
2)toroid is 630VA , biger than the original unit with indipendant secondaries for left,right ch
3)secondaries is chosen to 44+44 much lower than original unit for reliability reasons(k134-j49 max drain-sourse voltage is 140v so for a pushpull amp max theoriticaly voltage is 70v
practicaly a litle bit lower.I have seen PA amp with k135-j50 working at more than 90v without problem!,all haflers also!and never saw a failed MOSFET! Such a robust devices!,but nowdays are very hard to find so protecting them is a must!)
so my target goal is around 125wrms
4)heatsinks are very small for desapating continious 60+ Watts when qc is chosen @0,4A
and i think optimal for 45W in my case!
keeping OEM hafler boards is a very good choise(Symetrical design,JFET diferential input(xl280)(BJT for DH2XX),designed by the amp guru E.B.!) better than crap like musical concepts (http://www.musicaldesign.com/PA3E_INSA.pdf) and other e-bay boards!
ill try to go for something even better designing new drivers with best performance in mind,working on it allready for 3 months now
thanks in advance
your pics are very wellcomed!
Last edited:
Brain tickle - on this amplifier porn thread.
I am a third of the way, reading this entire thread,
having to take breaks so my head does not
explode... fall clean of my shoulders.
GREAT WORK EVERYBODY!!! Fabulous.
I am a 35 year Hafler veteran, builder
and extensive hot rodder...
I have been accused of absolute Hafler bias,
IT IS TRUE, I have worked to finesse every
bit out of "a venerable amplifier legacy".
I have a long standing relationship with John Hillig,
have learned one ~hell of a lot~ about amplifier design
and general electronics, mostly power supply designs.
I have over 100 Hafler builds (all modified, made correct
I cannot believe I have not seen this thread before.
Currently updating 4 PA-4 board sets, of various amps,
which I do struggle calling Hafler amps, at this point.
I am a certified Hafler Junkie myself, and live at Gardner Lake, a tiny lake about an hour from the Ozarks. I ran across a couple 200s today while cleaning up my shop and just now found this thread myself. I always knew these were pretty good amps, but didn't realize there was this much modding info around for them. I remember back when I got them, the idea was to bridge them to mono, which is why I have a pair. At the same time I bought these, I also bought a pair of transformers that was supposedly the hot ticket for bridging them. I'll need to dig those up and see if anyone has used them before, as I don't have a clue. The weather's getting cold here, so I'll be putting tubes back into the living room system anyhow. It should be fun to revisit these things, especially after I get time to read this thread completely.
The one thing to keep in mind is "let common sense be your guide".
These can be pretty good amplifiers and with minimal modding and simple device matching will perform at a much higher level while still being the amp you started with. It's too easy to get carried away and end up with something that bears little semblance to what it was supposed to be.
-Chris
These can be pretty good amplifiers and with minimal modding and simple device matching will perform at a much higher level while still being the amp you started with. It's too easy to get carried away and end up with something that bears little semblance to what it was supposed to be.
-Chris
I do wonder if after all these mods, what they measure vs the original design numbers. Yes some will argue against numbers comparisons, but it is better to know then not imo.
Kind of like an engineering check point or review. I usually do this practice with my mods, measure performance before and after every mod step. Keeps things in check/perspective, so to speak.
Kind of like an engineering check point or review. I usually do this practice with my mods, measure performance before and after every mod step. Keeps things in check/perspective, so to speak.
Now what?
Picked these two up for $100. Neither worked. One had cut cord so it may be a loss. Looks like they’ve both been tinkered with a few times over. I started to rewire one and investigate some obvious stuff and here I am...
Gut ‘em and rebuild? Find fix and flip? Back to stereo (both mono) I you had these what would you do with them?
Picked these two up for $100. Neither worked. One had cut cord so it may be a loss. Looks like they’ve both been tinkered with a few times over. I started to rewire one and investigate some obvious stuff and here I am...
Gut ‘em and rebuild? Find fix and flip? Back to stereo (both mono) I you had these what would you do with them?
