Static noise on my Hiwatt DR504... please help!

[Trotter]

So I found a 1983 50-watt Hiwatt DR504 at a Pawn shop today. They gave me a good deal on it so I brought it home (they do have a 7-day no questions asked, cash return policy) so I didn't have much to lose...

The amp sounds truly amazing with the exception of some "staticy noise" when I'm not playing. I tried swapping the tubes but the static noise is still there.

This is a very cool amp with a ton of mojo and I really don't want to take it back, but if it has an issue beyond fixing then I may have no choice.

Like I mentioned, it sounds amazing while I'm playing, but when I stop the static/noise is a bit much.

Any help would be very appreciated!

thanks all.

Lots of Pictures here:
http://picasaweb.google.com/cadfire/HiwattDR504

http://lh5.google.com/cadfire/RzAP5eK7_yI/AAAAAAAAAHU/r7S2F0S3UE0/s144/CIMG3037.jpg http://lh6.google.com/cadfire/RzAP5uK7_zI/AAAAAAAAAHc/KC32W31kdQk/s144/CIMG3015.jpghttp://lh6.google.com/cadfire/RzAP5uK7_0I/AAAAAAAAAHk/R4kQoQjKSUk/s144/CIMG3027.jpg

[Blue Strat]

If you got a good deal you should probably keep it. Typically, problems like these aren't expensive to fix. Preamp tubes, plate load resistors and signal capacitors are the most likely culprits.

See if any of the volume or tone controls reduce the volume of the noise. This will help to isolate the problem.

Try cleaning all the preamp tube pins and sockets. Check out the FAQ on my website under Resources for instructions.

[Swarty]

If you stole the amp, just call it good and fix it when you get around to it. If you paid decent money for it I'd try like crazy to fix it within the 7 days and it's still not fixed return it. Keep in mind this is not one the pricey hand wired/4 input Hiwatts.

[Structo]

Looks like it has had a filter cap replaced.
Try wiggling the preamp tubes while it is on to see if indeed a loose socket is to blame. If this changes anything, do what Blue Strat suggests about cleaning retensioning the sockets.
Try other tubes.
Be careful of lethal voltages!

[Trotter]

Looks like it has had a filter cap replaced.
Try wiggling the preamp tubes while it is on to see if indeed a loose socket is to blame. If this changes anything, do what Blue Strat suggests about cleaning retensioning the sockets.
Try other tubes.
Be careful of lethal voltages!


Other than the Filter Cap, does everything else look original?

thanks

[Blue Strat]

Other than the Filter Cap, does everything else look original?

thanks

The more important question is, how did cleaning the sockets work out?

[Trotter]

I will try today and let you know! Hopefully that helps!

[Tripower455]

If you stole the amp, just call it good and fix it when you get around to it. If you paid decent money for it I'd try like crazy to fix it within the 7 days and it's still not fixed return it. Keep in mind this is not one the pricey hand wired/4 input Hiwatts.


Actually, that is one of the last of the good ones. It was still hand wired, but used a heavy duty PCB instead of turret board construction. Note Harry's name on it! It looks like you got a fairly unmolested one too!

It appears to me that all but one of the filter caps have been replaced, but it's hard to tell from the pic. The Metallic blue one looks like an original LCR pr Plessy (I forget what mine had), but that one looks like the 50/50....... The earlier ones are laid out a bit differently. All but one of the filter caps are mounted on the top of the chassis. The 16/32 for the preamp is the only one mounted inside.

You can tell if the solder joints are original or not by looking for colored marker on them. The ones in my '79 were red, but I've seen green and blue. It quality assurance thing IIRC.

Like the others said, I'd start by cleaning all of the sockets, pots etc. A little hiss should be easy to fix. Also, you might consider reheating any of the non original solder joints, as you might have a cold one somewhere in there.

The important (read: expensive, like the trannys) stuff is good, so if you like the amp, I'd keep it. It is better built than just about all of it's contemporaries, and almost anything (production types) made today.


What did you pay for it?

[John Phillips]

No, it's still a PCB amp, the components are connected only to traces on the boards... just that it isn't a bad thing :).

I agree about the filter caps having been replaced, apart from possibly the dark blue one (probably a Daly or Erie, and made before the mid-80s most likely) at the bottom left, but the one that worries me is the one in the middle on the left - it looks like a possibly older type originally designed for PCB mounting, and may have been re-used from something else (eg a TV)... bad practice. I would replace it and probably the dark blue one as a matter of course if there's any doubt at all about their age or condition.

I'm guessing 'static' noises will be a failing plate resistor or coupling cap, as Mike said.

[gldtp99]

Looks like a Biacrown 2-Input PCB amp--- not a bad era of Hiwatt but not the most desireable, either.
Most of the basic troubleshooting has already been covered-----swap in known good/stable tubes--- checking/adjusting bias on EL34's as needed, clean tube sockets, clean pots------- i'd clean the input and speaker jacks---- clean the speaker ohms switch and the input voltage switch while you're at it, if it has one.
If all this doesn't cure it then replace the plate load resistors, as Blue Strat said---- around this point, if still not fixed, i'd most likely tap on components with a Sharpie pen (non-conductive-- all plastic) while amp is on (at low vol) to see if i could isolate the problem to a certain physical area of the amp (indicating bad solder joint or bad component)---- or you could just pull the PCB and re-melt all the solder joints.
It also could be a coupling cap that is leaking some DC---- voltage tests would find this.
After the static noise problem is eliminated, then i'd replace the filter and bias caps with fresh units.
I'd keep the amp and get it going properly--- prices on these aren't exactly going down.....................gldtp99

[Swarty]

Also does not look like Partridge iron. Still OK amp, at least not like a couple years later when tube sockets are mounted to PC board... like on my problematic Modesto, CA made Lead 20 head.

[John Phillips]

Also does not look like Partridge iron. Still OK amp, at least not like a couple years later when tube sockets are mounted to PC board... like on my problematic Modesto, CA made Lead 20 head.
And like the 100W channel-switcher I worked on a few months ago.

There was so much board damage I had to rebuild large sections (the power supply/rectifier board especially) with tag strips. It didn't have Partridge transformers either - although the PT is truly colossal on these, about the size of what you'd expect in a 200W amp. But surprisingly, once fixed it actually sounded pretty good...

These ones are made in England too - I'm not sure exactly who by (Hiwatt were a brand rather than a manufacturer at that time), but they have a lot of construction features of a certain other British Midlands-based company, and I would guess there may be a connection.

[Swarty]

FWIW, I've seen a few "tweener" amps apparently made prior to this one that were 2 holers with part PC board and part turret strip contruction. If I recall correctly these had toggles rather than rockers and also were sans Partridge.

[callaway_1]

In late 1980 Dave Reeves switched from Turret boards to these very heavy PC boards. These amps were still Hylight Electronics amps and they had toggle switches and Partridge transformers. The latest one of these I have seen was #15353 built in early March 1981 just before DR's untimely death.

[Trotter]

What did you pay for it?

$600.

...good deal?

[Tripower455]

Given the condition, I'd definitely pay that for it...... Think about what $600 will buy you today, and a hand wired (albeit PCB) 50 watter for that $$ is a steal IMHO.....


Nice catch!

Now, get you a couple of Fane (or Fane inspired) speakers in a heavy cab and you'll be set.......

[Trotter]

So, I finally found a few free minutes to work on the amp...

Cleaning the contact points made a huge difference, especially in the ohm selector... there is almost no static and after play through it last night for a good hour, I'm definitely holding onto this amp. It's got some absolutely killer tone and to my surprise actually sounds great at low volume!

Thanks everyone for the tips on getting the static out, I really appreciate it!

[Tripower455]

And another one succumbs to the dark side! Welcome!

[callaway_1]

That amp has the "OL" mod. It has a lot more gain than a standard DR504.

It looks to be a late 1984. Definitely a keeper for $600.

Congrats!

[Trotter]

Has a production sticker of 1983 in it.

[callaway_1]

Has a production sticker of 1983 in it.

That is the best indicator!

Some of the components really looked like those used at the very end of the Biacrown days.

regardless, it is a nice score!

[gldtp99]

Also does not look like Partridge iron. Still OK amp, at least not like a couple years later when tube sockets are mounted to PC board... like on my problematic Modesto, CA made Lead 20 head.
My Sterling/Hiwatt Lead 30 has chassis mounted tube sockets--- i cranked it up the other day and it's pumping out Hard Rock Distorted tones like it's supposed to--- then i put it away---- i like the Classic Hiwatt circuit much better lately....................gldtp99

[gldtp99]

So, I finally found a few free minutes to work on the amp...

Cleaning the contact points made a huge difference, especially in the ohm selector... there is almost no static and after play through it last night for a good hour, I'm definitely holding onto this amp. It's got some absolutely killer tone and to my surprise actually sounds great at low volume!

Thanks everyone for the tips on getting the static out, I really appreciate it!

I'm glad it was something pretty simple ---- i had one Silvertone 1484 with static-y noise problems that took quite a while to find--- it was a badly corroded fuse holder, all its brass contacts were covered with green gunky corrosion--- i cleaned it all out and the nasty noise was gone--- i'd tried everything else i could think of on that one and replaced some components that were perfectly good before i found the real problem.
Welcome to the world of Hiwatt----- but be careful, if you play an Early/Mid 70's 4 input DR504 or DR103 you'll be hooked forever..............gldtp99

[Tripower455]

That's funny, I have a little hiss in my '79, and I never even thought to try cleaning the imedance selector! It's never even been taken out of the 8 ohm position. It's not too bad, but compared to my clone, which is dead quiet, it is noticeable.

I'll give that a try when I get home!

Trotter,

What speakers are you running with it?

[Trotter]

Trotter,

What speakers are you running with it?

I've tried a 2x12 with Pre-Rola Greenbacks, and a 4x12 with V-30's both sound really good. However, I'm favoring the V-30's with that head just a bit.

What's funny is this amp was sitting on the floor in the Pawn shop for over a year. They wanted $1300 for it. Finally after over a year some guy put it on layaway for almost another year... paying each month for them to hold it... he stopped making the payments and the amp went back on the floor.

I was in there this last week and told the lady working there that I would love to have that amp, she said "make an offer"... I said $600 and she said "ok"!

This is by far one of the best sounding amps I've ever purchased.

[Swarty]

The older ones are prone to noise because of all the the wires being bundled together. You can undo it, and lose some of the noise, but who would want to destroy that beautiful wiring? I have a good friend w/ 26 Hiwatts from '68 through the Modesto era... all shapes and sizes... It is a pretty interesting the earliest one is a 50w PA head he got from me and it is not wired nearly as nice as some of the '70s pieces. Some are truely works of art!

[callaway_1]

The older ones are prone to noise because of all the the wires being bundled together. You can undo it, and lose some of the noise, but who would want to destroy that beautiful wiring? I have a good friend w/ 26 Hiwatts from '68 through the Modesto era... all shapes and sizes... It is a pretty interesting the earliest one is a 50w PA head he got from me and it is not wired nearly as nice as some of the '70s pieces. Some are truely works of art!

are you referring to Mike? He needs to come down to the Vintage HIWATT Convention next June!