The HK 430 - refurbished, revisited

[MD1032]

Some of you may have heard this from my initial Forte thread, but the HK 430 that I ordered on ebay unfortunately had a bit of a nuisance when I got it in the mail - an annoying low-level hum, in the 60 hz. region. I posted in Audiokarma and a guy named "ecluser" over there helped me out:

http://www.audiokarma.org/forums/showthread.php?t=164874

Well, basically, the amp is as good as new after the mods he had me do. I learned a lot about electrics and electrical engineering (and soldering) during the process (you'll see a change by the end of the thread in my knowledge), and in the end, the amp is a lot better off. The amp, though, definitely sounds much much better than when I got it. Not only is the hum probably 1/10 of the intensity it originally was, the sound is much improved. I ordered these larger, audio-grade capacitors as part of "fixing" the main amp board (don't worry, the stock ones are 4-pin, but they're snap in and two of the pins are dummies):

http://www.mouser.com/Search/ProductDetail.aspx?R=UFW1H682MRDvirtualkey64700000virtualkey647-UFW1H682MRD

Whatever they are, they definitely improved the sound. More detailed, less harsh highs, and bigger bass.

Bottom line, this amp is really singing now and I can finally see why it gets such a great recommendation. It blows my T-amp out of the water, frankly, regardless of how well-regarded that amp is.

Good stuff!

[tom b. 57]

Congrats. on the successful project.

I too have been impressed and do cherish my 430. Tomorrow I am picking up another one for $10.00 that needs a little work. The cosmetics are supposed to be mint. We will see. The one I have I have been using for two years now, off and on, and has always been pleasing to the ears. It's amazing that something this old can compete with newer higher rated (watts per channel) units and come out on top. Technology has come a long ways but when it comes to what one hears, some of the old stuff still prevails.

[Daddy Dee]

Congrats. That is really cool to redeem one of these classic receivers. Lots of them get junked when parts like that are worn out.

[fini]

Dee's right! Good of you to keep this gem out of the landfill! Carbon credits for you!!

[stan krajewski]

Last week I decided to fire up my HK430 which I bought on Ebay about 2 years ago but have not used on a daily basis. Anyway I sprayed the controls with deoxit and fired it up with my Sony playstation & Heresy 1 speakers (courtesy of Speakerfritz).

After an hour or so of warm up this little (and cheap) setup sounded great.

For the money, this combo is hard to beat.

These 3 pieces of equipment sing well together. I can hear that. Time and money would be better spent optimizing speaker placement or treating the room acoustically.

That should be my next venture - room treatment. It's the hidden piece of equipment.

As a side note, I "had" a Sansui 4000 receiver which is pretty much from the same era. Compared to the HK430 it sounded like a piece of junk.

Those HK?30's are special.

[colterphoto1]

Thanks - I need to do this. My 430 has hum and my 730 exhibits a startup noise that is so distracting that I always boot up with speakers disconnected.

Which end of the soldering iron do I hold again?

[MD1032]

My 430 still has that same startup noise (although to be honest, it's subtle and not much of an issue)... I'm convinced that's something else that needs to be dealt with separately, or I just need to entirely recap both the rectifier A and B boards. It's obviously some capacitor just audibly charging. The easiest solution if you really hate it is to just push the Speaker 1 & 2 buttons, turn it on, wait 5-6 seconds, and push them in again to reconnect the speakers. The problem before was that after the initial "HUUUMMMmmmmmmm....", it would continue humming. Now that drops down to almost inaudible.

But for doing this project, you need not worry: these boards are extremely easy to solder. I was sure that I had way overheated that first board while desoldering my first capacitor, but those brown/tan PCB's are extremely durable and forgiving. The green ones melt easily, though... [:$]

Still, I am entirely convinced that the 430 sounds much, much better now. Before I was like "eh, it could use more bass", now I'm levitating off my seat. Clearly, there was something wrong before. This amp opens up these Fortes now like swell shades on an organ!

Interesting story: When I first powered up the amp after replacing the main, I actually listened to about three tracks and thought to myself "this sounds pretty good, much better than the T-amp, and the detail is unreal, but it could use just a tad more bass", and then I realized that I had accidentally left the bass knob turned down all the way. When I brought that up to middle, my eyes almost popped out of my head.

Really, I went for the more low-end caps, even (although these are still gold audio-grade). I'd be curious to hear what the really high-end stuff does. It wasn't worth it for me to spend a lot on caps, though. This amp cost about $75 to begin with, then we figured out that FedEx was responsible for damaging something so they reimbursed me, so essentially I got it for free, but then I spent $25 on an old RMS multimeter (a nice one, an old Fluke), $8.00 on a new soldering iron and desoldering pump, and about $20 in capacitors. In the end, though, for about $60 spent...my GOSH... what a deal!

[KdAgain]

I have been using a 430 on my Khorns for several years and am basically pleased, although I sometimes wonder if I should redo some of the caps and other items. I also now and then get upgrade-itas and think perhaps a 'better' amp might be called for. Has anyone done any audible comparison testing with other supposedly better amps?

Thanks,

Rod

[tigerwoodKhorns]

Some of you may have heard this from my initial Forte thread, but the HK 430 that I ordered on ebay unfortunately had a bit of a nuisance when I got it in the mail - an annoying low-level hum, in the 60 hz. region. I posted in Audiokarma and a guy named "ecluser" over there helped me out:

http://www.audiokarma.org/forums/showthread.php?t=164874

Well, basically, the amp is as good as new after the mods he had me do. I learned a lot about electrics and electrical engineering (and soldering) during the process (you'll see a change by the end of the thread in my knowledge), and in the end, the amp is a lot better off. The amp, though, definitely sounds much much better than when I got it. Not only is the hum probably 1/10 of the intensity it originally was, the sound is much improved. I ordered these larger, audio-grade capacitors as part of "fixing" the main amp board (don't worry, the stock ones are 4-pin, but they're snap in and two of the pins are dummies):

http://www.mouser.com/Search/ProductDetail.aspx?R=UFW1H682MRDvirtualkey64700000virtualkey647-UFW1H682MRD

Whatever they are, they definitely improved the sound. More detailed, less harsh highs, and bigger bass.

Bottom line, this amp is really singing now and I can finally see why it gets such a great recommendation. It blows my T-amp out of the water, frankly, regardless of how well-regarded that amp is.

Good stuff!

Looks like an interesting project and a great result. Maybe you will go for an EE degree?

I learned this the hard way. If you are replacing parts on a 30 year old receiver, just buy all new caps and resistors for anything that you think needs to be replaced. If you forget one and have to reorder, the shipping can make it more expensive than just orderign all of them. Plus the labor of redoing the install.

Watch your pots. They were just cleaned and work well but after they are cleaned they tend to go bad a few times a year (needing a recleaning). If new sealed pots are available on the cheap you may want to replace them. You can also bypass the tone controls if you do not use them.

Great job on the project!

[MD1032]

Looks like an interesting project and a great result. Maybe you will go for an EE degree?

Watch your pots. They were just cleaned and work well but after they are cleaned they tend to go bad a few times a year (needing a recleaning). If new sealed pots are available on the cheap you may want to replace them. You can also bypass the tone controls if you do not use them.

Great job on the project!

Thanks! I'll pass on the EE, though. As much as I enjoy electronics and computers, I realized that I didn't have the necessary knowledge going into college to be a EE or CS and decided against it. I think it's the kind of thing you really need to grow up practicing to really be good at it. Besides, I really enjoy chemistry and I'm much better at that.

The pots, honestly, are just simply going to need to be replaced down the road, and certainly not by me with my rudimentary soldering skills on one of those green boards that melt at the drop of a hat. I already shot Deoxit in them, but I'm going to have to order some faderlube, too, because they're definitely responsible for about 90% of the noise coming out of the amp at this point... and it's a very low noise floor compared to before, but honestly, getting that part of the signal path cleaned up could mean a nice increase in SQ down the road. I'll have to find someone in my area that does that kind of service and get it done next summer. For now, as far as I'm concerned, it works very well.

Actually, there is no bypass for the tone controls, and if you know a jump I could do, let me know, I'll do it. I'd love to get the bass and treble controls out of the equation... unfortunately there is no defeat button.