My JBL 4355 build

[.:hb:.]

Just admiring Challenger604's beautiful 4355 project over at the "4355 Monitor plans" thread I thought it's time to give you a glimpse at my 4355 version. It is, of course, not finished yet (the cabinet is lacking surface treatment) but this is going to happen soon.
The cabinets are made of 25/20 mm beech ply, which is a really great material in terms of strength. But building such a beast from stuff that hard and heavy isn't exactly a piece of cake. But birch ply or MDF really can't compete with this, so I am finally happy after a lot of bruises and scratches .

I've made only minor changes to the original plans, for example there is now a support for the 2441 that really deserves the name and not that lousy sheet metal angle supporting the horn, not the driver.

Sourcing the drivers wasn't that easy here in Germany and so I ended up buying 2202, 2441, and 2405 in the US which didn't make things exactly cheaper, but everything turned out to be decent quality stuff, so I am fine with that.
The woofers began their lives as E140 and got freshly reconed to 2235H. At least that's what I thought, In fact the additional mass rings got folded, so I ended up with 2234H with a slightly stronger motor (due to the stronger magnetisation of the E140 magnets). That didn't turn out to be a real problem. With the original 28 Hz cabinet alignment, the system is tuned a little bit too low, which can be easily corrected with a bass equalizer.

[.:hb:.]

Finding the right colour for the baffle ended up with "RAL5007 brillantblau". The RAL chart is a standard colour code very common here in Germany - very useful, if you know the number, you can get (more or less) the same tone whereever you ask.

As for cabinet dampening, I didn't use the usual fiberglass stuff. It's not very effective and a pain in the a... to work with. I used a suitable amount of dirt cheap Ikea piilows, which is nothing but polyester wadding, exaxtly what we want here. Measurements showed tthe amount of absorbtion is just right.

The speakers made their first public appearance on last autumn's "European Triode Festival" in Berlin and did a really nice job. We had lots of amps and active crossovers to try, with some really unexpected results.

The actual state of things is to be seen on the last picture. I had to dye the diaphragms to black, otherwise I would have ended up with too many different tones.

So much for now, I hope you like what you see.

[BMWCCA]

Wow!!

Strong work. The build quality appears to be superb. Ikea pillows? Who'd have though of that. I'll have to remember it.

They look great just as they are and the blue color seems perfect on my monitor.

Thanks for sharing.

Welcome to Lansing Heritage!

[JeffW]

Great build! I bet there's not many of those in Germany.

Is that last pic at the Triode Fest? Looks like a whole lot of speakers of different types on hand.

[.:hb:.]

That last pic is taken in an old gym which serves us as measuring space. The second last is from ETF; you can find more impressions here: http://www.holgerbarske.com/etf2014/index.html

[.:hb:.]

Just starting to mount the acoustic lenses in front of the 2441s.
Does anyone know if the hook tape on the speaker front for fixing those is stapled or do we rely on the adhesive?

[Mannermusic]

Just starting to mount the acoustic lenses in front of the 2441s.
Does anyone know if the hook tape on the speaker front for fixing those is stapled or do we rely on the adhesive?

The adhesive alone has been adequate in my experience. Have done two or three horns. A staple would tend to warp the surface as well - not good. Can always add staples if all else fails. Mine have been in service approx 10 years to date.

[Ralf]

Great build! I bet there's not many of those in Germany.

Is that last pic at the Triode Fest? Looks like a whole lot of speakers of different types on hand.

There is already the next pair in the queue...I picked up all chassis needed for this project. The four 2235A are back now from remagnetizing, two of them still have to be repaired.
Today I bought a Weeke Optimat BP 12, a CNC wood worker machine...the project can be started soon...

Cheers
Ralf

[JeffW]

Good deal! Glad to see these builds popping up, look forward to hearing about yours.

[Mr. Widget]

Today I bought a Weeke Optimat BP 12, a CNC wood worker machine...the project can be started soon.

I just did a web search. That is one hell of a machine! Is this for your hobby or business? With a machine like that you could definitely crank out the speakers. Does it have three axis capability?


Widget

[Ralf]

I just did a web search. That is one hell of a machine! Is this for your hobby or business? With a machine like that you could definitely crank out the speakers. Does it have three axis capability?


Widget

It is just for fun...this is a machine owned by a friend of me who has a local wood worker factory. I helped him in the past to keep the machine up and running. Some weeks ago there was a problem with two broken coolers which caused an overheating of the controller CPU. He could not wait until a used part is available on the net and he decided to order a new machine. In the meanwhile we got a spare part, the machine is up and running again but he has no room for a second one. This was my chance to get this big iron for small money...
and yes, it is a three axis CNC with tool changer and all what is needed to build lots of speakers in the future...

Cheers
Ralf

[ivica]

There is already the next pair in the queue...I picked up all chassis needed for this project. The four 2235A are back now from remagnetizing, two of them still have to be repaired.
Today I bought a Weeke Optimat BP 12, a CNC wood worker machine...the project can be started soon...

Cheers
Ralf

Hi Ralf,

That is for the first time to hear that 2235A ever exist. On the other thing, to be re-magnetized....may be talking about 2231A....

ivica

[.:hb:.]

Yes, I was also wondering... Never heard of the necessity to re-magetize a ferrite motor.

[Guido]

That is for the first time to hear that 2235A ever exist. ivica

Come on boys!
.... Martin was faster but ....

"2235" stands for C8R2235 (Original of course). We do not make compromise here
"A" stands for Alnico core, thus the need for re-magnetize. In this case its a K140 core.

And
No, the K140 is -unlike the E140- not to strong for the C8R2235 kit. It is a substitude for the 2235 core and shows exactly 1,20T after remagnetize.

Yes, the 2 unfinished woofers lying around here and waiting for me to FINALLY get them done.

[Challenger604]

Finding the right colour for the baffle ended up with "RAL5007 brillantblau". The RAL chart is a standard colour code very common here in Germany - very useful, if you know the number, you can get (more or less) the same tone whereever you ask.

As for cabinet dampening, I didn't use the usual fiberglass stuff. It's not very effective and a pain in the a... to work with. I used a suitable amount of dirt cheap Ikea piilows, which is nothing but polyester wadding, exaxtly what we want here. Measurements showed tthe amount of absorbtion is just right.

The speakers made their first public appearance on last autumn's "European Triode Festival" in Berlin and did a really nice job. We had lots of amps and active crossovers to try, with some really unexpected results.

The actual state of things is to be seen on the last picture. I had to dye the diaphragms to black, otherwise I would have ended up with too many different tones.

So much for now, I hope you like what you see.

Did you finish your trims around? I saw the work to take the base off and routered the front. Just wanted to see the result!
Will you veneer them?
Christophe