Page 1 of 1

My first Hiwatt DR103 (1979) - is it ok?

Posted: Thu Feb 28, 2013 4:36 pm
by ckaydrag
Hi everyone!

Finally in the club - bought a 1979 DR103 amp. After the euphoria of the purchase fell off I discovered this wasn't an ideal bargain and the amp has some issues so I'd like to hear from hiwatt-experienced people.
The amp is missing voltage selector plug but I already ordered the replacement. Funny thing but I waited so long for it but still didn't turn it on to try (waiting for voltage selector plug, correct fuses and answers for some questions below)
The main questions for now are:
1. Is the amp recapped and if not - does it need the recap or is fine for now?
2. Is there any seen modifications?
3. There's a crack on one of the transformers (picture №4) - is it critical or doesn't matter at all (seen some pics of other partridges - seems mine have a crack just in cover)
4. I'm not sure if the amp was used or not without voltage selector - as I understand it could but then it means it was wired internally for one of the voltage options so I need to unwire it for using with selector plug. Please tell if it was wired internally (if my pics are detailed enough to see this)
5. Output valves and biasing - there are Groove Tubes EL34 now but I don't know if it was biased for them. If not - how would it affect the tubes and amp (maybe shorter tube life or something)?

Here are the pics of the amp (if needed more detailed or different angles - please let me know).
The photo of the inside (last one) in original size is here - http://img268.imageshack.us/img268/1179/img1233du.jpg
I would appreciate any answers :)
IMG_1244.jpg
IMG_1244.jpg (212.41 KiB) Viewed 1366 times
IMG_1248.jpg
IMG_1248.jpg (481.31 KiB) Viewed 1366 times
IMG_1234.jpg
IMG_1234.jpg (373.13 KiB) Viewed 1366 times
IMG_1245.jpg
IMG_1245.jpg (382.38 KiB) Viewed 1366 times
IMG_1246.jpg
IMG_1246.jpg (291.48 KiB) Viewed 1366 times
IMG_1249a.jpg
IMG_1249a.jpg (393.77 KiB) Viewed 1364 times
IMG_1233a.jpg
IMG_1233a.jpg (407.38 KiB) Viewed 1366 times

Re: My first Hiwatt DR103 (1979) - is it ok?

Posted: Thu Feb 28, 2013 5:04 pm
by Dr.HI-TONE
Hi Welcome to The Vintage HIWATT forum,

it has been hardwired for 115v.

The cracked cover on the transformer should not be an issue.

If you are going to gig with it, it should have a cap job. if You are just playing with it at home it is OK for a while.

have you played through it? When powered up, do the plates inside the tubes get red hot?
if the bias is too cold the amp will sound brittle
if the bias is too hot the tube life will be diminished

Re: My first Hiwatt DR103 (1979) - is it ok?

Posted: Thu Feb 28, 2013 5:41 pm
by OldSchoolDave
Obviously, the Mains fuse holder is a replacement. Also, whoever labeled the preamp tubes inside the chassis made an error. "V4" is actually the middle of the group of three.

Other than that, it looks like a fairly unmolested Hiwatt. Congrats!

Dave

Re: My first Hiwatt DR103 (1979) - is it ok?

Posted: Thu Feb 28, 2013 5:50 pm
by ckaydrag
Thanks, guys!

I plan to use it at home for a while. I didn't play through it yet cause I will run it on 230v and need to replace the Main fuse and take off the 115v hardwiring.
How often should I check the caps for bulging?

It's nice to hear that amp looks almost untouched.
And thank you for tube number correction - it's very important cause I'm going to try NOS Mullards and ECC81 in the PI (V4 is the PI, am I right?)

Re: My first Hiwatt DR103 (1979) - is it ok?

Posted: Thu Feb 28, 2013 5:58 pm
by Dr.HI-TONE
correct V4 is the PI

you will have to fix the mod to operate it at 220v.
simply putting the plug in will probably destroy the transformer without correcting the mod.

remove the small section of green wire that connects the brown wire (from mains fuse) to the 115v lug on the selector.
solder the brown wire to the center lug of the selector.

Re: My first Hiwatt DR103 (1979) - is it ok?

Posted: Fri Mar 01, 2013 5:47 pm
by ckaydrag
Yes, a read about voltage selector on hiwatt.org and I got the idea what should be fixed. Maybe i firstly rewire it for 230v to finally play through and when I get the selector plug replacement - then fix it to the original state.