Hafler Amp Restorations

[tubesglo]

Before my Dynakit ST-70 I ran Hafler amps for over 30 years. I always enjoyed the smooth mosfet sound. I was given two DH-220's last year and finally got around to begin restoration. I installed Musical Concepts PA6 driver boards with larger power supply caps in the first one. I knew the sound would be great because I did the same with my DH-500 over 20 years ago. The 2nd DH-220 is going to be a bone stock restoration.These are great budget amps with incredible and very respectable specs. They sound wonderful.

 

[Mike414]

Nice to see some love for the "vintage" Hafler gear. I still have my Hafler DH-220 amp, DH-110 preamp, and tuner I built somewhere in the early 80's. I haven't used them since discovering tubes. Often thought about the Musical Concepts upgrades. I need to dust them off and see if they still work.

 

[tubesglo]

Nice to see some love for the "vintage" Hafler gear. I still have my Hafler DH-220 amp, DH-110 preamp, and tuner I built somewhere in the early 80's. I haven't used them since discovering tubes. Often thought about the Musical Concepts upgrades. I need to dust them off and see if they still work.

I had a ST-70 back in the early 80's and ironically I shelved it when I built my DH-500 in '85. I ran that amp almost 20 years before I installed Musical Concepts boards. I'll tell you what, my 220 and 500 with my Cornwall clones both sound absolutely sweet, especially the 220 with MC PA6 boards. It would be difficult for anyone in a blind test do distinguish it from my tube amp, it's that friggin' good. Very smooth highs with no etching at all and the bass is tighter and better defined than the tube amp. The DH-220 with the upgraded driver boards is a very nice way to go that gives the best of tubes in the highs with that solid state bass control. I restored a ST-70 a few years ago and that will be my winter amp while I rotate the 220 in the summer. The 500 will be a backup for my theater rack and I may weld with it in my garage occasionally, 😅 the things a monster.

 

[old_borg]

Running your 500 without the relay? Do tell...

 

[tubesglo]

Power from the driver board direct to speaker post. Bypassed relay and speaker fuses over 20 years ago, never an issue. I use a CL thermistor to slow initial surge, very mild turn on thump.
If I ever sold the amp I'd wire the 48v relay back in...but that ain't happening. I'll never sell this one.

 

[old_borg]

Mine is on my workbench... for a relay replacement. Will have to look into this alternative as it really did sound wonderful with current power hungry speakers.

 

[MrEd]

I had a 110 preamp and a 280xl amp for several years.

 

[tubesglo]

Mine is on my workbench... for a relay replacement. Will have to look into this alternative as it really did sound wonderful with current power hungry speakers.

Mine did great with 4ohm Thiel 2.4's, never broke a sweat. It truly is a great amp. The upgraded driver boards brought a higher level of refinement to the sound.

 

[tubesglo]

I had a 110 preamp and a 280xl amp for several years.

Those xl series are really nice.

 

[avguytx]

I always liked those Mosfet Hafler amps and has been forever since I owned one. I do, however, own a quite rare bird of a Mosfet amplifier originally made by Rockford Fosgate. Sales didn't go that well since they were a big car audio company and some stuff got "forced", in a way, onto Hafler and they tried with them as well. They were basically the old school Power 1000 amplifiers built into a home amp. It uses 32 Mosfet, is also bridgeable, and lists 8-ohm power in the manual as "over 200 watts per channel from 20hz to 20khz" and over 300 at 4-ohm and has peak output current of 50 amperes. It's quite the beast. I bought it over 5 years ago and hooked it up but it was no worky. I emailed various people I knew from my past life in the industry (including RF as I was a rep for them) and they came up with some minimal info on them. You see these and the Hafler version come up on auction once in awhile and the last Hafler went for $480 and RF for $580.

I decided to get my Dynakit ST-70 out on Monday and hook it in place of the modified Carver M-1.0t and really enjoyed how it sounded. Then, I hooked up the Rockford RF2000 amp, which I had got working BTW, and was quite amazed at how it sounded. I'll be honest....it's going to stay in place for awhile. I never gave it a fair chance...or maybe I was too lazy in moving that 40 pound amp around. lol Oh, and it uses two caps in the PS at over 80,000uf combined with a HUGE torroid transformer. I believe the Mosfets are TO-220's. I thought I had a picture of the huge caps and the (I think) 8" diameter transformer but I guess I don't.

An inside shot...



And a shot of the torroid and 40,000uf caps (from the web)

 

[tubesglo]

I always loved Rockford Fosgate amps. I still have a Punch 100 I bought back in the mid 90's. I haven't used it in almost 20 years but can't part with it for sentimental reasons I suppose.

 

[avguytx]

Oddly enough, even after selling RF at retail starting in 1984, then being a manufacturers rep for them from 2001 till 2009, I don't have any RF gear. Nor any car audio at all, for that matter. Only the memories and maybe some pictures of all the stuff we built at the stores I was at in the retail time. A long time tech friend in Little Rock, who works on most everything, wouldn't touch this amp. He said he's "not comfortable working on them and those Mosfet's fail if you breathe on them wrong". ha.

 

[tubesglo]

Yeah I've long since been done with car audio. The factory systems have come a long way and I see no need to change them anymore. RF amps were the shit back in the day, balls galore.

 

[avguytx]

Yep.... Good times. Built quite a few systems in the early days of competitions using a single or two Punch 45's in mono/stereo setup with fairly elaborate passive networks. Use to be those 0-50 and 51-100 power classes that were so much fun to build. Orion had their 225 HCCA red amp which was a bad boy, too.