It would make sense to draw the original schematic with designated/measured parts values, before the upgrade.
If you haven't already, measure the capacitors.
If they are within tolerance, I see no reason to upgrade, except for fun.
If they are within tolerance, I see no reason to upgrade, except for fun.
Fun is all the worthwhile goal, especially for those getting started. 🙂
According to the service manual, the internal wiring is "Defence Standard 61-12 Part 6 Type 3".
This single, flexible, multi-strand equipment wire is used within electronic equipment in military and industrial applications, commonly being used in aircraft and in military vehicles.
I reckon it's good enough for a pair of domestic speakers! 😉
I drew up the schematic for this B%W DM305. I assume it's the usual Kevlar 6.5" cone and 4 ohm metal tweeter.
R1 would be 1-2R if fitted. Maybe 7W.
Looks like the tweeter is wired negative polarity given that red and blue go to earth on the PCB in the photograph supplied:
The PCB:
Quite a low crossover on the bass I think. Maybe 2.5kHz. About 3kHz on the VERY standard 8ohm tweeter circuit. So you might expect a bit of a hole there. The 1.8R will adjust the 4 ohm tweeter to nearer 6 ohm DCR.
I suppose you could put a 2.2R (3W) in front of the tweeter circuit if you wanted it 2dB quieter.
I find I have fiddled around with these things before on a simulator. The B&W 602S3:
The idea was to try to take out some horrible Kevlar bass breakup around 5kHz with the 22R / 0.68uF tank across the bass coil. With a 1.4mH coil, 0.47uF might be better.
It's the hobby!
Best Regards from Steve in Portsmouth UK.
R1 would be 1-2R if fitted. Maybe 7W.
Looks like the tweeter is wired negative polarity given that red and blue go to earth on the PCB in the photograph supplied:
The PCB:
Quite a low crossover on the bass I think. Maybe 2.5kHz. About 3kHz on the VERY standard 8ohm tweeter circuit. So you might expect a bit of a hole there. The 1.8R will adjust the 4 ohm tweeter to nearer 6 ohm DCR.
I suppose you could put a 2.2R (3W) in front of the tweeter circuit if you wanted it 2dB quieter.
I find I have fiddled around with these things before on a simulator. The B&W 602S3:
The idea was to try to take out some horrible Kevlar bass breakup around 5kHz with the 22R / 0.68uF tank across the bass coil. With a 1.4mH coil, 0.47uF might be better.
It's the hobby!
Best Regards from Steve in Portsmouth UK.
wow, thank you very much, I thought I could find things on the Internet but was not able such a detailed service manual, only first 2 pages 🙂
I'm aware exchanging capacitors may not bring better results ... but as noted, it is a hobby 🙂 I do not have any measurement device, I can do only some basic iPhone recording before & after ...
Sure, curiosity is what got me hooked on electronics. Quite a few old tube radios didn't survive.
Keep us posted on your progress. 😎
B&W uses 8, 4 and 11 uF capacitors, not sure if I can use ones from the upgraded sample (4.7 and 10 uF).
Mundorf's closest is 3.9uF ... https://www.mundorf.com/audio/en/shop/capacitors/MCAP---CLASSIC-250V/?card=5118
Mundorf's closest is 3.9uF ... https://www.mundorf.com/audio/en/shop/capacitors/MCAP---CLASSIC-250V/?card=5118
3.9 is a standard size. It's close enough to 4. As with any change, you should expect to have to make adjustments anyway.
ok, so all done 🙂 I will describe my findings:
I have exchanged all capacitors, here I'm sharing what crossover looks like now.
Thanks all for great support and information here 🙂
- I have got Elac Debut 6.2 as at least some reference to start with. At first side-by-side playing sound from Elac was clearly better, vivid, and more detailed than from my B&Ws. Even my wife voted the same, so proven 🙂
- then I exchanged capacitors in the first speaker and did a comparison from the second one - it sounded different - ok, some progress there
- I have exchanged a second speaker as well and connected again, side-by-side with Elac
- now, it was clear, B&W started to be better. It had the same vivid sound, some clear hights, and a lot of details, but the sound was more "spread" (sorry for my explanations). Maybe it was their position or direction, but we liked them more. My wife voted again, but now for B&Ws
I have exchanged all capacitors, here I'm sharing what crossover looks like now.
Thanks all for great support and information here 🙂
if somebody may be interested ... I'm posting update:
For these speakers I replaced ferrofluid in the tweeters, original was almost "honey" like, new was real fluid. It brought clrify and even more details to the highs. Also I have upgraded cables to MOGAMI 3104 OFC.
Now interesting fact - I have borrowed KEF LS 50 Meta, connected them to my setup and did not like to sound compared to my upgraded B&Ws. I have played with possitioning BW's and did not notice a difference with space as well ... I'm extremely happy with these upgrades 🙂 Old and cheap BWs now plays great, even owner of KEF was surprised.
For these speakers I replaced ferrofluid in the tweeters, original was almost "honey" like, new was real fluid. It brought clrify and even more details to the highs. Also I have upgraded cables to MOGAMI 3104 OFC.
Now interesting fact - I have borrowed KEF LS 50 Meta, connected them to my setup and did not like to sound compared to my upgraded B&Ws. I have played with possitioning BW's and did not notice a difference with space as well ... I'm extremely happy with these upgrades 🙂 Old and cheap BWs now plays great, even owner of KEF was surprised.