Hafler DH-101 preamplifier

ViperZ

Hey all,

Finally built some kind of a 2-channel rig with Carver TFM-24 and Magneplanar MG-II... Now need to fix a preamp.

I need replacement potentiometers (yes, all 3) for the Hafler DH-101 preamplifier.
The problem is - the original build manual does not even say what kind of potentiometers those are - impedance is not listed, linear or logarithmic, etc.

The (Hafler) part numbers are: 164001 and 194001 (looks like a dual potentiometer, I don't have the original).

There are tons of potentiometers available through digikey and other suppliers, but I'll need to know the values first. I can make an educated guess (being an electrical engineer) and can check the values on DH-110 (already did, but it's a different pre)...

Thanks!

fbm211

Musical design/concepts might be able to help you with that.Contact john hillig. http://www.musicaldesign.com/contact_us.htm

ViperZ

fbm211 wrote: »

Musical design/concepts might be able to help you with that.Contact john hillig. http://www.musicaldesign.com/contact_us.htm

It's pretty amazing. After calling several places, John was the only person who had the parts and sounded very competent.

Thank you!

fbm211

And if you ever need any mods done he is the person to talk to and do buisness with.Kind of expensive but I think you would get the best bang for the buck with his company.

ViperZ

Ordered the potentiometers and the whole whack of resistors and capacitors from digikey (recover the original tone circuit, and update power supply and signal path capacitors). Will update when the parts will arrive .

TroyD

I've had that Haf preamp.....it's a nice pre, however, for what you'd spend in parts to keep it running I gotta think that it would be better spent on a new pre. Don't get me wrong, I love David Hafler and his gift of making great gear on the cheap.....

BDT

ViperZ

TroyD wrote: »

I've had that Haf preamp.....it's a nice pre, however, for what you'd spend in parts to keep it running I gotta think that it would be better spent on a new pre. Don't get me wrong, I love David Hafler and his gift of making great gear on the cheap.....

BDT

I kind of got carried away with all the parts buying, but I have heard and read a lot of good reviews regarding modded and unmodded Hafler DH-101. At least I will get a taste of Hafler gear before jumping onto something more expensive in the 2-channel world.

Eventually, I will need a 2-channel preamp with a subwoofer output. I don't know if such thing even exists . I would love to hook up the Magnepan MG-II flat panel speakers together with Velodyne ULD-15, which I recently completely restored from literally pile of parts. Any advice on the preamp is definitely welcome!

Systems

ViperZ wrote: »

Eventually, I will need a 2-channel preamp with a subwoofer output.

Do you just want a summed left and right output and or low pass filter for the Velo? These should already be integral to the Velos plate amp.
If you wanted to add a hi pass filter to roll off the bass in the Maggies you could easily retrofit a simple op amp based filter circuit into the Haflers chassis.

ViperZ

GV#27 wrote: »

Do you just want a summed left and right output and or low pass filter for the Velo? These should already be integral to the Velos plate amp.
If you wanted to add a hi pass filter to roll off the bass in the Maggies you could easily retrofit a simple op amp based filter circuit into the Haflers chassis.

GV, you're right - the ULD amp has a built-in low-pass filter, but it only has 2 line level inputs (no speaker level inputs).

If I won't find the amp with a built-in 2.1 circuitry, I will follow your solution and will add an extra active low-pass filter to Hafler. It has tons of space inside - for the DH-102 additional phono stage, which I won't use.

ViperZ

Question: has anyone built these preamps before? If so, how do you count the lug/terminal numbers on the switches(buttons)? The manual usually says "connect xxxx wire to lug #1 of SS switch". How do I know which lug is #1? Where is the reference to start counting on those switches?

Thanks!

ViperZ wrote: »

Hey all,

Finally built some kind of a 2-channel rig with Carver TFM-24 and Magneplanar MG-II... Now need to fix a preamp.

I need replacement potentiometers (yes, all 3) for the Hafler DH-101 preamplifier.
The problem is - the original build manual does not even say what kind of potentiometers those are - impedance is not listed, linear or logarithmic, etc.

The (Hafler) part numbers are: 164001 and 194001 (looks like a dual potentiometer, I don't have the original).

There are tons of potentiometers available through digikey and other suppliers, but I'll need to know the values first. I can make an educated guess (being an electrical engineer) and can check the values on DH-110 (already did, but it's a different pre)...

Thanks!