• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Hafler DH-200...expierences, mods, repairs?

vinyldavid

vinyldavid

Collectorius Giganticus
Subscriber
Well, I sent out an email to some friends into audio, telling them of my decision to go into separates, and asking for amp recommendations, given a yamaha C-4 or C-80/70.

I am getting a Hafler DH-200.

I've heard that these can be modded, and it looks like this one has been.
It has: new internal wiring, some cap upgrades and bypasses, one output module replaced, and new output terminals.

So, has anyone ever had one before? How have they liked it?

And most importantly....anyone know how to troubleshoot these if it does not work upon arrival?
 
Register to hide this ad
hi david, i ust bought one today from te local electronics store. i still havent played it yet. i waiting on info for the dc offset on it. seem to be within reason. but i asked about it in the offset thread.

good luck.
 
They're a lot of fun, those old Haflers. Search around AK as I know we've had many, many discussions about them.

Also if you just want to mess around with some of the more standard mods, hit AudioXpress for back issues with lots of POOGE articles. Seems to me they may have republished them as a book, too. Lots of the improvement steps were done on old Hafler gear.

To keep it stock, though, you'll need to go through the driver boards and replace some of the caps, I suspect. Myself, I've swapped the old driver boards for ones from Musical Concepts, which really kick those old amps up a notch or 2. Van Alstine also has upgrade boards and mods kits, IIRC.

Hope that helps.

Cheers,

David
 
There was a factory-offered mod (a small circuit board mounted internally) that allowed the two channels to be bridged into a 200W monobloc amp. I know someone who has two of those modded amps (in her attic!).

--Bob
 
dshoaf said:
They're a lot of fun, those old Haflers. Search around AK as I know we've had many, many discussions about them.

Also if you just want to mess around with some of the more standard mods, hit AudioXpress for back issues with lots of POOGE articles. Seems to me they may have republished them as a book, too. Lots of the improvement steps were done on old Hafler gear.

To keep it stock, though, you'll need to go through the driver boards and replace some of the caps, I suspect. Myself, I've swapped the old driver boards for ones from Musical Concepts, which really kick those old amps up a notch or 2. Van Alstine also has upgrade boards and mods kits, IIRC.

Hope that helps.

Cheers,

David
Click to expand...

If it's working when I get it, I'll just leave it the way it is. If it's not, I'll start looking through it (downloaded it) with my DMM and see if Ic an troubleshoot it.

I've seen the musical fidelity mods. It's definitely an amp that I can improve to a far higher plane than it was originally.
 
Don't forget, though, that these amps use some cool-but-no-longer-available output devices. The amps themselves are tough as nails. I use mine to drive a set of Quad ESL63s and they don't even blow the fuses. Fun!

Cheers,

David
 
They're good amps, designed by the guy who designed the Dyna ST-70.
I would recommend getting the Van Alstine mod kit if you can...
 
A great sounding, workhorse of an amp even in stock form. Had one for years driving ADS L-810 IIs and it was a match made in heaven. The MOSFETs are particularly good with bass.

Good luck.
 
-Replace the electrolytics on the driver boards
-Upgrade the input capacitor or at least bypass it with a small value cap
-Replace the RCA inputs
-Check the BIAS
 
VintInfinity said:
stop giving him ideas! :)
Click to expand...

:lmao: I don't think that my budget likes all of this idea-giving.....

bordeno said:
A great sounding, workhorse of an amp even in stock form. Had one for years driving ADS L-810 IIs and it was a match made in heaven. The MOSFETs are particularly good with bass.

Good luck.
Click to expand...

This is good to hear :yes:

willyrover said:
-Replace the electrolytics on the driver boards
-Upgrade the input capacitor or at least bypass it with a small value cap
-Replace the RCA inputs
-Check the BIAS
Click to expand...

According to the guy that's giving it to me: some caps have been upgraded and bypassed, and the output connectors have been replaced. Looks like someone did some of those upgrades already.

And how do I check the bias?

bolly said:
http://audiokarma.org/forums/search.php?searchid=4821477
Click to expand...

Tjat gives me just a 'no mached found'.
 
hi david, mine appears to be in stock form. and ill second or third or fourth or fifth or sixth the mosfets being good with bass. im using mine with a pair of RSa, with a m70 on another pair of RSa. initially it sounded way dark. but after adjusting(volume close to one watt (m70 meters) even half that it sounds good. and yes its a nice sounding amp evem in stock form. like you im not able to buy upgrades left and right. children get hungry you know?!
 
I've been a Hafler fan since I bought and built my DH-500 & DH-110 in 1981. I have said many times it's the best (just under) grand I ever spent! It finally fell victim to a lightning surge a few years back, one of these days I'll fix & upgrade her. I have a DH-220 that's my "go-to" amp, whenever I need something powerful, reliable and good sounding!

These amps are sleepers, and have been proven to hold there own against amps costing much more! I always get a kick out of some of the reviews of the 500 at the link below, especially the ones that pertain to the abuse these things can take:

http://www.audioreview.com/cat/amplification/amplifiers/hafler/dh-500/PRD_115810_1583crx.aspx
 
The upgraded boards, transformer and PS cap company is Musical Concepts not musical fidelity.

The bridging kit gives a power output of 300 wpc not 200.

All you need to know here on AK and search will reveal most of it. This includes how to test and set the bias.
 
Blue Shadow said:
The upgraded boards, transformer and PS cap company is Musical Concepts not musical fidelity.

The bridging kit gives a power output of 300 wpc not 200.

All you need to know here on AK and search will reveal most of it. This includes how to test and set the bias.
Click to expand...

I figured out the Musical Concepts thing fairly quickly...but their webiste is not very well laid out, IMO.

I'll search around AK and see what the procedure is, and then measure the bias/DC offset, and then go from there.
 
From the DH-220 manual (the procedure is oddly enough not found in the DH-200 manual)To set BIAS power off and remove all speaker and input connections then:

1. Remove B+ fuse. (Inline between + capacitor terminal and driver board.)
2. Connect ammeter + to fuse clip on capacitor side.
3. Connect ammeter - to fuse clip on driver board side. (Avoid intermittent connections.)
4. Power amp on and adjust BIAS trimpot (only pot on DH-200) to read 250mA. (275mA for DH-220)
5. Turn amp off and when current drops to 0mA remove meter and replace fuse. Repeat on other channel.

(From the looks of my pic I had my leads reversed. Don't think it matters on a digital MM.)
 

Attachments

  • IMGP0754.jpg
    IMGP0754.jpg
    125.7 KB · Views: 333
  • IMGP0753.jpg
    IMGP0753.jpg
    76.4 KB · Views: 370
Last edited:
willyrover said:
From the DH-220 manual (the procedure is oddly enough not found in the DH-200 manual)To set BIAS power off and remove all speaker and input connections then:

1. Remove B+ fuse. (Inline between + capacitor terminal and driver board.)
2. Connect ammeter + to fuse clip on capacitor side.
3. Connect ammeter - to fuse clip on driver board side. (Avoid intermittent connections.)
4. Power amp on and adjust BIAS trimpot (only pot on DH-200) to read 275mA.
5. Turn amp off and when current drops to 0mA remove meter and replace fuse. Repeat on other channel.

(From the looks of my pic I had my leads reversed. Don't think it matters on a digital MM.)
Click to expand...

:ntwrthy:

Thanks!
 
You must log in or register to reply here.
Back
Top Bottom