z-adamson
Addicted Member
Some would argue that replacing all the transistors, capacitors and diodes on the boards with new equivalents would count as restoration related activity.
Hafler DH200, DH220 restoration questions
- Thread starter z-adamson
- Start date
Blue Shadow
Waiting for Vintage Gear from this century
yes, you do seem to be arguing but for a restore or a hot-rodding, I don't know.
There is that thread on DIY, it has the information. Good Luck.
you can post up your choices and see how that flies.
There is that thread on DIY, it has the information. Good Luck.
you can post up your choices and see how that flies.
z-adamson
Addicted Member
My goal to to bring it back to what it (my dh200) was when it brand new and fresh out of the quality control dept of the hafler factory.
I call this a restoration. Not a hot-rod and not a resto-mod.
Thanks again for the link. I will read through it.
The Fuxtor
Addicted Member
If you come up with a decent BOM , please post!! I have 2 sitting awaiting restoration myself!
eickmewg
Well-Known Member
I've replaced a number of components in my DH-200. As far as caps go, I used a kit from qua-co that had all the caps, electrolytic and non-electrolytic, for both boards. I also had a bad driver on the right channel. I took out all the transistors for that board for testing purposes. I found the culprit but replaced them all with another qua-co kit which included a matched differential pair that improved my DC offset. I probably could have gotten all the parts for half what I paid, but the kits came with nice illustrations/instructions and it saved me the time it would have taken to order all the parts. My DH-200 sounds as good as the day I finished building it back in 1981. The boards are very easy to work with and the traces are pretty durable so first-time DIYers, like I was, have it good.
So I have 4 Hafler P505's, (same amp as a DH500) but you can run them in Mono. I had them completely rebuilt using the kit from Ed at Qua-co, he was an engineer for Hafler. I also did the power supplies, now I do not have the skills to do electronic work so someone else built the boards for me from Ed's kit, after I received the boards and power supplies, the amps were rebuilt in Buffalo by Precision Audio, I have been using them now for almost a year, and all I can say is that the difference in the sound is unreal, hearing things in my music that I have never heard before. Yes I spent a lot of money to do this but for me it was worth every penny.
Blue Shadow
Waiting for Vintage Gear from this century
You can crank out a bom by using the OM parts list and the info from a Qua-Co Audio offering on the bay. He says he uses poly caps for bunch of replacements and some lytics and some ceramics. I don't understand changing the ceramics or film caps, but an extensive rebuild could include these. His kit does not include the big caps, though.
The advantage of his other kit, the semiconductor kit, is that the transistors are matched. These would be much better matched than you buying a handful of the transistors (2N5401 and 2N5550) and matching them yourself. But that service costs a bit buying the kits, two required for the 2 channels.
These kits are good for those that don't want to do the work of building a BOM and ordering the parts...then matching the transistors that need to be matched, leaving a bunch of leftover transistors.
call it what you want - it's a battle of definitions. that thread on diyaudio is not just about
refreshing 40 YO caps and such, there's other threads about re-engineering the driver
boards with custom designs, etc.
the goal for ALL - keeping these out of the dumps, landfills, roadsides, decaying barns
and, more importantly, bring it up to working status and to do so - to keep it working
for another couple decades.
refreshing 40 YO caps and such, there's other threads about re-engineering the driver
boards with custom designs, etc.
the goal for ALL - keeping these out of the dumps, landfills, roadsides, decaying barns
and, more importantly, bring it up to working status and to do so - to keep it working
for another couple decades.
Stavro
Active Member
My preference is to keep my two Haflers as stock as possible. My 220 is as good today as the day I got it in 1986. My XL-600 is stunning as it is. Never had the need to soup it up. They have the transparency and more than enough power. Just my opinion. The key is to use them every so often so the electrolytics don’t deteriorate. Also using them with a good line conditioner makes them sound even better.
Blue Shadow
Waiting for Vintage Gear from this century
Stavro
Active Member
A couple of TrippLite line conditioners. Both 2400 watts. Makes a huge difference. I am in NYC. Apartment buildings etc.
z-adamson
Addicted Member
I beg to differ on this point. The way that solder flows from one side of the board to the other makes component removal especially difficult. On top of that there is little to no markings on the board in the way of labeling to indicate which leads of the components go where.
I would say oem hafler boards are among the most difficult to work with.
sunvalleylaw
Addicted Member
Can you or someone else describe for me what the difference in performance is? I am curious. I have a Hafler P-225 that I love the sound of, but am curious what else could be considered over time.
z-adamson
Addicted Member
You should peruse the ebay listing for the quaco kit that Ed sells. He has detailed specs there complete with wave forms to show for the specs. I personally have built 3 amps with his kits and can say that he does not exaggerate at all with his published specs as I have been able to duplicate them.
Stavro
Active Member
I would leave it stock. If you like it and it works within specifications, why change? Far too many people selling snake oil out there in my opinion.
Blue Shadow
Waiting for Vintage Gear from this century
The Hafler is a bit different. Quaco is a former Hafler employee selling nice kits to restore the amps and kits to improve them with new boards and such.
Musical Concepts is another well known supplier of parts to redo these amps. They go a good bit futher, leaving the heatsinks, chassis and Mos-Fets as about the only parts left when the full upgrade service is used. This is a great upgrade by all accounts, costly but it brings the amps up to the level of some high end gear available today.
Nothing wrong wth keeping them stock but with the over 100-page discussion on DIY audio there are many things that can be done to improve the amps in small steps. The above two can be a small step, the cap kit or a major rebuild, restore, upgrade.
I would immediately install any Musical Concepts parts into my Hafler DH-200s if they were to show up on my doorstep. I have other amps but I've had these since new and assembled them from the kits. Other than a recap and a few of the DIY audio upgrades these are essentially stock and sound fine. Not my best amp but then they were never intended to be the best amp, nothing David Hafler supplied to the audio community was the best, just almost always the best value for the money and these amps sure do meet that criteria.
UncleBingo
Super Member
The basic character of the amp was retained (smooth treble response) but the amp had much deeper and tighter bass response. And that's with ADS 910's which will go deep.
The Fuxtor
Addicted Member
The Hafler dh-200/220 & 500 are proven to be very upgradeable
