Hafler DH-110 Preamp Restoration

[@jimkaeseberg599]

Replaced both Jfets and the LM393 all with sockets. Works like a charm. Thanks so much for the info. I now have my Hafler back.

[@georgechambless2719]

I assembled one of these back in 1985. My first entry into 'real hi-fi". I was a new college student/aspiring audiophile. Main circuit board was pre-assembled and tested. Great entry into the world of high quality audio. Hard to believe they are old enough now to need 'restoration'!

[@rodgerwilliamson8393]

Well, I remember selling you this pair at Shelby years ago. I still have one more of the 220 amps running my bedroom system. I built and installed the upgrade kit in that amp as well. Maybe I will see you at Shelby this year. Enjoyed seeing the videos!

[@Uncle_Buzz]

Some really great "best practices" nuggets in here. Thanks for sharing your knowledge.

[@geterdunn2733]

Really good video, you’re a good instructor and I certainly appreciate you sharing your knowledge.

[@martinvanek5951]

I built this preamp back in the 80s and am currently recapping it. If the board was marked incorrectly it would not have worked after assembled. Perhaps kit units are more careful about marking the boards. Good advice when it comes to factory assembled units. Thanks.

[@MODAC]

Wow, I used to own those back in the early 80s. They were amazing.

[@robertweinmann9408]

I was hoping that you would take a dive into the volume pot as it looks to be a sealed component. I have a similar master volume pot on my Sansui CA-2000 preamp. It's a huge black plastic Alps pot that has gotten a bit noisy in one channel. i am very hesitant to take it apart for a proper cleaning and lube. Love your clear explanations on all that you do.

[@zulumax1]

I'm working on my son's DH-110 again. The RCA jacks on that board are only held mechanically by the solder joint. When you have it apart these should be resoldered, or inspected very closely for fractured solder joints. My Sansui AU-7700 has the same problem and has been apart many times to repair fatigued solder connections. Maybe JB weld to shore up the mechanical stress may work, but I haven't' tried that yet.

[@MrDoneboy]

Thanks Mark, another great video, as always!

[@aarontaylor2906]

Thank you a great restoration and teaching video! 😊

[@sirsuse]

Great series! Love the channel as well.

[@daver2067]

The hole in the rack mount cover is for the Hafler DH yellow indicator light. The light comes on when you had it cranked up for 3 days straight and it started to get a little warm I have 2 DH 200’s restored and I challenge anyone to find a better built amp for the price

[@mosfet500]

I built the 220's and then built a DH500 power amp (both had the same finals). It was so so in my view, I had a lot of trouble with the pwr transistors and one board finally burned up. Couldn't find the mosfets 20 years ago finally found some super expensive replacements and sold it, just too problematic and the sound was good for the time but not great. I still have the DH110 which was a very highly rated preamp at the time but I like the sound of tube hybrid preamps better tied to class D amps. By the way David Hafler designed a 60 watt per channel transistor amp back in the late 60's that was a big deal back then but it continuously blew pwr transistors too. Cheap kits and for us builders it was the way to get decent sound, I'll give it that.

[@sabelli33]

Please, I would like to ask a question: would it be worth repairing a Hafler DH200 and pairing it with an AMC CTV 1030 preamplifier with a pair of Dynaudio 52 speakers and an Arcam cd73 CD player?

[@garthhowe297]

Great series of videos! Thanks!

[@lmt200ish]

You don't bother with finding the band end on non polarized capacitors for noise reduction in audio?

[@srtamplification]

Mark's Marks. Great idea!

[@Wizardofgosz]

So did you ever figure out why they included all those polypro caps in the kit? I mean when you first opened it up and showed the kit I was asking myself where those were supposed to go since I didn't see any on the board?

[@raycimbalnik5159]

I have a question, I have a 1978 Yamaha CR-2020 that I purchased recently and the guy threw in an older pair of Technics speakers that sound good for what they are. I thought I'd try the reciever with my klipsch r28f that I use for home theater, and the mid bass drivers sound blown. Real floppy sounding even at low volume. So I connected the Klipsch back to my Denon and they sound fine?? Any idea what could be going on? The Yamaha does sound a bit punchier than the Denon but doesn't seem like that would do this

[@1974UTuber]

Hi Mark, TECHNICAL QUESTION: Can 2 x 117 Volt Tfrs be wired in series to run on 220 Volts? Trying to better understand transformers. Just rewatching your series on explaining Tube Amps and living in Australia we have 220 Volt supply although I measure 245 V at the wall outlet in my house.

[@lynnpoole7830]

HI, I have a(Superphon) Revelation Basic preamp circa 1986 (approximate). It a dual mono design By Stan Warren (the S in PS Audio. It got rave reviews back in the day. None of the caps are swollen or leaking. Should I recap it because of its age? Thank you so much.

[@seanobrien7169]

Is it broke?

[@lynnpoole7830]

@@seanobrien7169 Nope. So i'm guessing leave well enough alone.

[@seanobrien7169]

@@lynnpoole7830 Your call. Recapping would be playing it safe, but I don't know if I would mess with it until I felt it needed it. EDIT: Let me add that Mark found some bad caps in this one and i assume it was working fine. I am also not too sure that changing the electrolytics in a preamp would effect the sound like it MIGHT in an amp. Not opening that can of snake oil though...

[@lynnpoole7830]

@@seanobrien7169 Thanks Sean.

[@sirsuse]

In my experience Marantz is horrendous for screen printing errors and revisions. Never recapped a Sansui. I mostly work on Pioneer and Carver gear.

[@MrBillmechanic]

excellent !!!

[@gionag]

Where ? HERE

[@Wizardofgosz]

So wait a minit. You're telling me that the the entire time you were working on this, you never once checked the part number on your schematic, and compared it to his part list, and saw that he included 220s instead of 470s????

[@pilotpete2]

The Hafler specs for those caps is 220ufd. After Hafler sold out to Rockford Fosgate, RF substituted 470ufd, since they used a boatload of that capacitance in other models. The 470's were cheaper for them to use. At least, that's what I've been told.

[@Wizardofgosz]

@@pilotpete2 ah..

[@zulumax1]

The new straw on the D5 is terrible, it wastes product, it is too big, and you need to buy an adapter to downsize the straw to a smaller size that can get in the small holes of a potentiometer. They call it the perfect straw because it sucks! I also miss the low, medium, high variable setting of output pressure of the old can. So what if I loose the straw, any straw from other products, WD-40, carb cleaner, brake clean, etc. will fit. They are all over my shop.

[@jimcatanzaro7808]

Most of the cap kits on eBay is the biggest scam I had many problems with him most of the caps have more then 20 percent off value

[@tubeDude48]

Soldering Iron NOT Soldering Gun! :) --- Maybe you got a bad DeoxIT D5 straw. I love the flip-straw, and none of mine leak...

[@Barbouri]

Not impressed. "I bought a capacitor kit, but I don't like buying capacitor kits" A little research would have helped, as you are not the first person to recap a DH-110.

[@seanobrien7169]

He brings up that exact point. These boards changed throughout production, the schematic or parts list might be off what is actually in your component. I don't think he was trying to impress you, just help out us amateurs.