my DR-504 from 1974-75. Is it ok?

[nicolasDR]

hello hiwatt experts & lovers !

Please have a look of my recently-bought DR-504, serial number 7916 - with a "tested 30-4-75" sticker. What do you think of it?

It has no sound-issues whatsoever but compared to my DR-103 the sound is slightly thinner and with less 'resolution' / clarity.
Maybe this has to do with the tubes, they seem warn-out. I do not know about the caps.

Preamp section: 1 Valvo, 2 Mullards + 1 tagged "S-S....". Output section: 1 Valvo + 1 unknown

thank you !

now the pics... Hope you enjoy them !

photos 00 - 03





board photos 04-07





transformers & caps





serial no. & sticker




front panel-close up on broken indicator lamp-cover


..and finally, close-ups on the tubes

[Dr.HI-TONE]

it looks nice! It is a shame that the mains lamp is broken, but it is a very nice amp!

Welcome to the forum!

[nicolasDR]

Thank you!

i ll try to glue the indicator lamp cover , i must have it somewhere
Can anyone tell if i need to replace the electrolytic capacitors?

thanks again! nice to be here

[Dr.HI-TONE]

I would change the electrolytics. Can you see the bulges on them? That indicates that they are on their last legs.

[OldSchoolDave]

Can anyone tell if i need to replace the electrolytic capacitors?

It certainly wouldn't hurt. Those look to be the original Radio Spares and Plessey caps. A couple of bulges are visible in your photos, but I've seen worse. Still, a new set of proper filter caps could help restore some punch.

I'd also suggest putting the ECC83 with the most flashing in the V1 socket (the one all by itself) and, perhaps, getting a different pair of output tubes. Drop a pair of inexpensive JJ E34L (as opposed to their EL34 model) tubes in there and see if it makes a difference. By all means, hang on to all those old tubes, though!

Dave

[nicolasDR]

thank you Dr.H & David!

i ll replace first the EL-34s (its happens that a friend has a pair of JJ-E34Ls for me) and see what happens.
Then the V1 & preamp tubes and finally a re-cap in the future. I just needed to know that i can still operate it for a while without causing big problems.

By all means, hang on to all those old tubes, though!

Yes sir !

[lffish133]

I would definitely re-cap your amp, I re-capped my 50 watter and it did make it sound more full.