(Yet ANOTHER) DR250 Build Thread!

[escapemcp]

Last night's shenanigans:

The first job was always going to be running some decent voltage through the cab. I wanted to hook up the voltmeter to check voltages, so tried to position this so that the probes were touching the + and - terminals on the crossover. I couldn't seem to get a reading at all, until I realised that it was reading perfectly fine... it was just that the cab had very little voltage (0.1V) going through it to make the noise that it was making A good start It was then onto the sound test... turned up the volume and finally got it. These things are LOUD! I noticed a bit of shrillness in the HF, so did a rough and ready RTA (indoors ) in order to tame this. Now I could give it the full beans and as soon as I did, the BFM smile returned to my face! Compared to the Otops (from memory - I'll do a better comparison soon Grant) they seemed to be the same SQ wise, but quite a bit louder.

I then returned to the more mundane tasks. I attached the double half moon cutoffs in order to create a back. The tweeter array also got a lick of paint, some neoprene tape and 8 more screws to hold that sucker in place... no rattling. A sad moment last night though, as the crossover from Otop #1 was removed, thus rendering it mute Once removed I could check to see if my rough measurements for fitting in the crossover parts were ok:



I reckon that'll be ok to fit in there - that lpf inductor is the biggest part by far... I may have to have a multi level crossover, but I know that there will be plenty of space between my inductors, so they won't be interferring with each other I'm really starting to like the 'external' crossover idea... means I can do quite a bit of troubleshooting on the cab without having to get into the driver chamber.

Anyway, that's about it for last night. I've also decided to get a track saw next month - I can see how much time I could save with one, and that's not even considering the improved quality of cuts, accuracy of bevels, dust reduction etc etc. I think that may just shoot straight into the "Most Valuable Tool" position it will certainly be MVT in terms of $£¥€!!

[Tom Smit]

Anyway, that's about it for last night. I've also decided to get a track saw next month - I can see how much time I could save with one, and that's not even considering the improved quality of cuts, accuracy of bevels, dust reduction etc etc. I think that may just shoot straight into the "Most Valuable Tool" position it will certainly be MVT in terms of $£¥€!!

Ack! You going for being an authorized builder? You certainly are on track!

[escapemcp]

Tom,

Every time I use the circular saw & sled, I'm now thinking that it would be SO much easier with a track saw. The decision/justification to buy has already been made in my head and so the van is going to have to wait yet another month!! I just wish I had bought one at the start of all this woodworking/speaker madness!

[88h88]

You're gonna make me buy a track saw now.

[escapemcp]

88h88: Buyit, buyit, buyit, buyit, buyit, buyit, buyit

Last couple of days have been spent neatening the overhanging edges of the cab:



Buyit, buyit, buyit, buyit

And quite a bit of listening - this is my rough and ready indoor RTA result:



It may have been done in the garage, but the DR now sounds better than it did.

Buyit, buyit, buyit, buyit

[escapemcp]

It's been a while, but for the last 2 months it's been all work Totally re-doing the network at the school where I work has taken all of my time and I have only recently had enough energy to get back into the garage and build.

One thing that helped me back into the shop is my new toy:



It's made my work FAR more accurate and cuts that would have previously taken me 10 mins to get set up can be done in a minute. It means I'm no longer saying "that'll do" and I now aim to be spot on with my measurements.

So, W.R.T. the speakers, this is speaker #1:



You can see the removable back and the space in the cheek cleft where I will be fitting the crossover (which will be attached to the back panel).

Speaker 2 is lagging a little behind:



I used waay more PL than I should have getting the butt cheeks on this one the other night, and as I have a gig on Saturday (shit... 3 days ), I've been forced to use the runny PL (pictured on top of the speaker). For some glue-ups, it works well, as it's runny, so I can let it run into gaps. But that also causes a problem if the surfaces to glue aren't flat.

You can see how much it foams in this pic:



'Standard' Euro-PL on left, bottled PL on right. I probably put a bit more into the RHS, as I let it run down into the gap, but it wasn't a lot. I reckon it's increased in size about 10x!! You can also see how runny it is by the drips... I turned the speaker 90° whilst the glue was still setting, and you can see the checkerboard result on the side!!

More to follow real soon (if I get a few minutes to post). I'll also post a review sometime after I've recovered on Sunday.

It's good to be back

[escapemcp]

Sorry for the extended delay everyone. I was doing a network upgrade at the school where I work, so that has taken all of my time up for the last 2 months. I did manage to get the system out recently though:



The speakers were thrown together on the Saturday of the party. Only managed to get both working at 10pm! As such when I went back to them recently , I have had to do a few repairs. The main problem was to remove a whole load of PL - I used the runny stuff in a bottle toward the end (to attach the sides) as I had run out of 'tube' PL. This was a particularly bad bit after I had removed the glue:



That's a lot of PL going to waste (although rather that than not using enough!!! )

The real reason for this post though is to show you guys how I installed the filters:



I have a 4 core coming out of the driver chamber into the buttcrack. I used some 6mm (1/4") ply to create a back and then mounted the crossover on another bit of 6mm ply. This was then attached to the back panel on some 12mm (1/2") ply risers (just visible) to allow enough space for the zip ties. I didn't make the 6mm ply cover the whole back as I needed some 12mm for strength and structure in the handles. I am happy with the end result. If I get any crossover issues, I can easily fix them without having to dismantle half the speaker

[escapemcp]

Sorry for the zombie thread reanimation, but I'm just looking into buying some more wood and I noticed that the bendy ply that I previously purchased is too thin compared to the 1/8" requirement in the plans

The stuff I have used is classified as:

PEFC™ Finnish Grade III Quality, 3-Ply Birch Aircraft PlyWood Bond Class EN314-3 Specification EN636-2S
An ultra-lightweight panel, with a consistently fine surface, yet strong with excellent bending properties.

3-ply birch veneer with exterior bonding throughout. The AB face is joint-free. AB/B

AVAILABLE THICKNESS (mm)
1.5 (that's 1/16" in old money)
PANEL SIZES (mm)
1500 x 1500

Using my very limited knowledge, I think that I am more worried about the effects of this error on the horn sheaths rather than the butt-cheeks, but as my DRs are ported is this going to make much/any difference? Will I be losing output?
I suppose it's too late to do much about it now - I think someone one here may have mentioned some sort of wood stiffener paint in the past. Do you think I should try to remedy the situation, or just run with it?
Saying all this, I can't imagine how hard bending 3mm (1/8") ply must be... I had enough trouble with this stuff!

[hifibob]

Lookin good escape.. Maybe I missed it but how do u like them so far? What did you have previous to the DR's?

[escapemcp]

I had the Otops before, but just couldn't resist the urge to build the 'premium' tops. TBH I was initially a little disappointed with the DRs, not because the DRs are bad, but rather because the Otops are so good and not that far off the DRs in terms of performance. I was expecting more from the DRs after hearing the Otops. Just goes to show that if you can't build DRs, then Otops are definitely the way to go as you won't be sacrificing much performance by building the 'easier' cabs. DRs are definitely better though.

This was the last time the kit went out:



And this was the result:



A good party ruined afterwards by the Welsh Police!

[Bill Fitzmaurice]

A good party ruined afterwards by the Welsh Police!

Should have played nothing but Tom Jones.