Hafler 500 Upgrade

motorhead43026

Sweet, some serious capacitance going on there. That thing is going to be a beast once you are done.

machone

Got the board, rectifiers and components for the power supply upgrade.

machone

I installed the ps upgrade last night.

Removed caps, rectifier and installed standoffs.


Board populated and tracks filled with solder.


PS installed.




Fired it up with a variac and checked the ps output voltage, all good. Installed the driver board fuses and checked the bias, all good less than 5mv.

Put back in the rack and fired it up.

I am impressed. No noise, very musical and rock solid but very delicate at the same time. These modern capacitors are quite amazing. Definitely more tactile bass while cymbals slowly decay and recording room ambiance is enhanced. I could not be happier.

I had goosebumps with body rushes.....

I am out of town for the weekend and can't wait to get back and listen some more.

gp4jesus

motorhead43026 wrote: »

Thanks, I really want to get the XL600 freshened up. I love these big Haflers.

a side benefit to doing PS upgrades* in the XL 280s & 600s is they come from Hafler w/separate rectifiers & cap banks for each channel making the aforementioned* easier.

gp4jesus

To the OP: did MC provide the wire to connect to the binding posts or did you reuse? In my XL280 I found subtle & not-so-subtle improvements using better/heavier wire for the above & PS caps to driver boards.

machone

I replaced the wire B-B+ from the ps to the driver boards but not the wire from the driver boards to the speaker posts.

machone

I got 150 hours on the PS upgrade.
It's really really good.
Smooth as silk.....

machone

Just hit 300 hours.

Really opened up with a powerful bottom end. Wrap-around 3d soundstage. I did not expect this upgrade to have such a positive impact on SQ. I am pleasantly surprised.

Do these 2.3TL's have a limit !?

machone

I replaced all of the wire running from the power supply to the driver boards and from the driver boards to the binding posts with 12 awg. Also, I replaced the 35 year old thermal paste under the MOFETs.

Clipdat

What type of thermal paste did you go with?

machone

Clipdat wrote: »

What type of thermal paste did you go with?

https://www.parts-express.com/nte-303-silicone-thermal-heat-sink-compound-1g-tube-5-pcs--nte303

machone

Well, after rewiring the power supply to driver boards, driver boards to speaker posts and replacing the thermal paste under the MOSFETS the amps mojo fell off. I had an oops o-carp moment.

250 hours later the mojo is back in spades. It took that long for everything to settle and burn in!

It is sounding great

audioluvr

machone wrote: »

I replaced all of the wire running from the power supply to the driver boards and from the driver boards to the binding posts with 12 awg.

What wire did you go with?

machone

What wire did you go with?[/quote]

I got it through Musical Concepts.

MarkTMeyer

Hello, any further updates or impressions? Anything you would differently? btw : where did you purchase the oslo power switch, is it lighted?
Thanks!!

machone

I've had a lot of fun and learned a lot upgrading the Hafler. Very little original except the chassis and mosfets.
I would not change a thing but I would like to try Musical Concepts new PA7 frontend someday.

Got the HD lighted switch from Musical Concepts.

MarkTMeyer

Just upgraded my speakers to Acoustat 1+1s , My Musical Design D75 dies, and I'm digging out my old DH500. Had purchased many years ago PA-3b boards and dual mono transformers. Going to use the PA-3B boards , transformers, and update to the most recent MC dual mono board and Mundorf 15,000 Caps. Anxious for the parts to arrive to get started. Ordered Mundorf 1500 caps for the on board PS for the PA-3B, will have the Mundorf and a set of Blackgates for the other caps on board. Will run these for a while until I can upgrade again to PA-7s.

machone

The power supply is a definite upgrade. I think you will be pleased. I also added an IEC socket and upgraded the power cord.

MarkTMeyer

Have mogami wire to construct power cable, along with Connex Power/IEC Plugs Rhodium-Plated Copper , along with IEC rhodium /copper receptacle.

levier

Machone... I have recently purchased a working DH500, planning the exact upgrades you have done. How is documentation/ instructions from John? I have experience rebuilding, upgrading Dynaco ST400, with success, pretty sure I can follow good set of instruction.

Did you have any issues getting responses to questions? Not familiar with filling solder tracks, is this a hot plate or oven procedure?

Thx...

machone

Excellent instructions and support. John knows Hafler. I used a soldering iron to heat and fill the tracks with solder.
Have fun!

levier

Thank you!