Hafler DH 220 amp sounds like tin can

[Robcf]

Just took possession of a Hafler DH220 amp and DH110 preamp. The DH220 sounds incredibly "tinny". Ran a couple of preamps through it so am sure it's the amp. The only way to get any decent low end is to turn the DH110 bass tone control to 10 and the treble to -2.

Intended to mod the amp with the Musical Concepts PA-3B boards, but now am wondering if I'm going to end up in the deep, dark, expensive mod-repair vicious cycle....

Anybody familiar with this problem in the DH220, or other solid states for that matter?

Thanks!!
RC

 

[bear]

there are two threads currently on this amp...

also, it shouldn't sound "tinny" - if anything a normal 220 sounds
a little bit fat and round...

I'd check the feedback network for yuks and the input cap(s) - perhaps someone has put in a cap as a HP filter for bi-amping duty??

_-_-bear

 

[Bogie]

Have you tried a different preamp? I just ebayed a 110 last week, and when it arrived, sounded VERY muddy on one channel - it's going back.

IIRC, John essentially guts the amps/pres anyway - replaces the boards, transformers, etc - I think about the only thing that's original are the mosfets...

 

[Zen Mod]

Just took possession of a Hafler DH220 amp and DH110 preamp. The DH220 sounds incredibly "tinny". Ran a couple of preamps through it so am sure it's the amp. The only way to get any decent low end is to turn the DH110 bass tone control to 10 and the treble to -2.

Intended to mod the amp with the Musical Concepts PA-3B boards, but now am wondering if I'm going to end up in the deep, dark, expensive mod-repair vicious cycle....

Anybody familiar with this problem in the DH220, or other solid states for that matter?

Thanks!!
RC

if I understand corectly-volume is not in question , just quality of sound
?

if volume is low ,and sound is thiiiiiiiiiiiin! , then loudspeaker fuses are gone,and you have output through tiny capacitors, soldered in para with fuses.

 

[Sze]

also, it shouldn't sound "tinny" - if anything a normal 220 sounds

I have to agree with Bear. Must be something wrong with the amp.

I have a DH-220 modded to up to a Musical Concepts GXB mod at one time, until I accidentally blow it up. Slip of a meter probe. The mod made significant improvement to the stock amp. I rebuilt the amp to its stock state, save for the MC toroid, Supply caps and TRT wondercaps. Definitely not tinny sounding. Use it as back up if other projects are in working stages.

 

[anatech]

Hi Robcf,
Your amp has open caps in the feedback to ground connection near the input transistor side. Easy to fix. Replace the other caps while you are there as they are commonly open or reduced in value. I've fixed many. As an added touch, match the transistors in the diff. pair locations. That is worthwhile. Then have a listen.
-Chris

 

[fab]

hi robcf

In addition to the other previous comments, if the "tinny" sound is present on both channels (L +R) then - unless the defective parts in respective channels have passed away a long time ago at different time - it is maybe a defective component that is common to both channels like: the power supply. With no input signal, check the DC voltage (maybe about 65V for a DH-220?) and the AC voltage (less than a few hundred mv).

Good luck!

Fab

 

[Robcf]

Great feedback guys, really appreciate it!

I'm an audio engineer and occassionaly use the soldering iron on gear, but this might require someone more skilled then I. Been looking for a place that will work on this amp and haven't come up with a good source yet.

What a great forum, thanks for the assistance and happy holidays!

 

[anatech]

Hey Robcf,
This is no more difficult than swapping the bad parts with good. Just mark the board where the line on the caps are (-). The values are on the parts. You will need 4 X 100uF 100V and 2 X 470uF 16V non-polarized. These are all radial lead, electrolytic capacitors. That will do you for both PC boards. The 470uF caps are the main culprit.

-Chris

 

[still4given]

This is exactly how I got interested in DIY in the first place. I had two P230 Haflers that both played very distorted. I took them to a tech and he gave them back, after charging me to look at them, and told me he couldn't fix them because the trannies were bad and NLA. I found two NOS trannies on EBAY and bought them. After swapping one out I found no change. I started asking folks over at the JBL forum and they helped me find that it was bad Filter caps. I replace those and the amps play like new.

Since then I have fixed two Soundcraftsmen amps and am now nearly finished building an ESP P101 amp.

With all of the helpful folks here, I am not afraid to tackle things that used to make my head spin.

Thanks guys!

Terry

 

[Robcf]

Thanks for words of encouragement Terry.

This was the first purchase I've made on eBay (and there have been plenty!) where the seller was not truthful. I'm a recording engineer and composer so wasn't necessarily looking for a non-musical project, but am so excited about completing a new project studio with audiophile quality playback that this will be worthwhile. Intended to drop major bucks into the amp with the Musical Concepts upgrades but will try the simple route first.

From your experience is it necessary to test with a volt ohm meter after replacing all the caps? I'm a little rusty with using testers.

Thanks!

Rob

 

[anatech]

Terry,
It's too bad you were charged by the tech. It is normal practice to not charge for an incomplete repair unless the tech has been "forced" into the job. On top of that, the tech was too inexperienced and misdiagnosed the problem. Sad.

Rob,
If you got the caps in backwards, they would test okay with the meter and still go bang when powered up. So, coffee, pay attention and "juice it up".
-Chris

 

[amp_guy]

dh110 with soil in it

HI Bogie:


I know you said you sent the 110 back but i thought i would tell
you what was wrong (possibly)

there is a jfet in each channel used for output muting they go out all the time and either kill the output entirele or give it a murky sound. you can either replace it or just remove them both as i do.

by the way this preamp only has 470uf filter caps and benifits
greatly by adding 10k uf or so

i dont know maybe this info will help someone

 

[still4given]

Terry,
It's too bad you were charged by the tech. It is normal practice to not charge for an incomplete repair unless the tech has been "forced" into the job. On top of that, the tech was too inexperienced and misdiagnosed the problem. Sad.

Rob,
If you got the caps in backwards, they would test okay with the meter and still go bang when powered up. So, coffee, pay attention and "juice it up".
-Chris

Well, he told me there would be an $18 charge if he couldn't fix it.
I didn't mind that so much as the misinformation he gave me. Truth is, he could have fixed it if he had known it was the caps. Lucky for me he didn't or I wouldn have never learned all that I have in the last few months.

I was tempted to go back and tell him but I was afraid he would think I was rubbing his nose in it. That would be burning a bridge that I may have to cross again someday.


Blessings, Terry

 

[anatech]

Hi Terry,
At least it was only $18.00 US. I guess the hardest thing to learn is to keep an open mind. Most techs I know seem to look only in the first direction they think of. It is amazing how much you can get through with an open mind!
-Chris

 

[still4given]

Yeah. I'm not sure why he said it was the transformer. With what I know now, it was a simple test to see that the trans was putting out the voltage. The ripple is what gave away the caps.

Like I said, once I learned that I was able to fix all 4 amps.

Blessings, Terry

 

[jmgreenlee]

hafler repairman needed

I need someone to do some work on a DH-220. Any recommendations? I do not have the skills, but would like to farm it out to an honest individual or shop.

Dick West, I tried to e-mail you but the e-mail address I have for you is no good. Can you contact me? jmgreenlee@sbcglobal.net

Thanks!

JMG