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Thread: 4345 Hybrid Build

  1. #1
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    4345 Hybrid Build

    I picked up my newly constructed cabinets a few weeks back, so thought I’d share a couple pics and describe what I’m building.


    After considering the investment in tools and the (re) learning curve to make a decent box, I decided to get a quote on completed enclosures. I ended up having Mr. Joe Stewart of Utopia, ON build the cabinets. I highly recommend Joe. He has an ad on Canuck Audio Mart.


    I’ve been researching the 4345 for quite some time and LH is of course where most of the relevant information is to be found. It was very instructive to review the build threads, Q&A threads, and the plans.


    I originally decided to build an M2 and had many of the parts. The 4345 kept tugging at me, and I came close to pulling the trigger on a pair of clone 4345s. In the end I decided to combine what I consider the best elements of each system:



    1. 4345 cabinet per LH plans, with minor changes. What can I say, I love the monster look and it’s necessary to get the low frequency performance.
    2. Keep the 2245 and 212x (in this case 2123) because according to many that is where the real magic is in this speaker.
    3. Replace the horn and the 2405 with the D2 from the M2, using the STX825.
    4. Skip the crossover system and make this fully active, via DBX drive rack Venu360.

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  2. #2
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    That’s a nice project

    Keep us in the loop

  3. #3
    Senior Member macaroonie's Avatar
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    Your fabricator has done a great job on those cabs, three cheers for Joe Stewart

    I'm liking your POA here , it should work out great. One word of caution , the high build of the grille frames is there due to the original lens but may not work favourably with the waveguide. You may find a null caused by reflection back from the grille frame.
    You will see this of course as you check the response and to a certain extent the DBX can sort that out , but better if the prob was not there in the first place,

    Good luck with the rest of the project.

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    Quote Originally Posted by macaroonie View Post
    Y One word of caution , the high build of the grille frames is there due to the original lens but may not work favourably with the waveguide. You may find a null caused by reflection back from the grille frame. You will see this of course as you check the response and to a certain extent the DBX can sort that out , but better if the prob was not there in the first place,

    Good luck with the rest of the project.
    Thanks for that observation. I'm not sure if there will be an issue with the standard height grille but i'll definitely keep that in mind. You are probably referring to mid-hi frequencies, as the original version flush mounts the 2405 and does not suffer (or does it?).

    I do expect some dialing in, first with the grilles off then with on. And yes, I'm counting on the DBX to have enough adjustability to put this right.

    That's a ways off. I'm still chasing down mounting bits and pieces for the drivers. I'll post an update pic when everything is secured attached

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    You might find most users have dispensed with the grills. They have quite an industrial design look that many (woman) find appealing.

    I have never played my 4345 clones with grills on over the last 15 years.....Lol

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    Quote Originally Posted by Ian Mackenzie View Post
    You might find most users have dispensed with the grills.
    Dang, late to the party yet again. That might explain why some veneer the baffle or at least ditch the blue. I'm OK with my choices for now, the grill can become a dust cover during inactivity.

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    They’re good for keeping curious little fingers of those precious cones

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    Construction Pics Highlights

    A few of the snapshots Joe sent me during construction:

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  9. #9
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  10. #10
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    This is a cool build. I had a similar build recommended to me by someone when I was pondering the practicality of cloning some of the older 43XX drivers.

    Is the waveguide you're using the PT type that Dayton sells a clone of? I have to admit ignorance with waveguides and horns and the sort... I am slowly trying to learn. I have seen the SEOS as well, and had them suggested as a viable alternative for a large scale monitor. Not sure.

    The gent in Ontario who built those did a mighty fine job. Makes me wonder if it's practical to roll my own or contact someone like him. Plus I am in Ontario, so that may help

    Looking forward to the progress on these. Are you going to have any controls or plates on the front baffle like the originals or just a big blue face?

  11. #11
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    Very nice build, thumbs up!!

    I actually had a similar idea of using a different horn in a 4345-hybrid.
    What made you choose the little waveguide?
    What is it you donīt like with the genuine mid-lens?

  12. #12
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    Thank you both for the kind words.

    I've been battling what seems to be really bad allergies lately, so progress has been slow. I've got the T-nuts fitted to one cab and just received the lining after researching here ( #7 amazing, a 14 year old link that worked!).

    Quote Originally Posted by mortron View Post
    Is the waveguide you're using the PT type that Dayton sells a clone of?
    These are the JBL waveguides which I learned about from Member srm51555 who pointed me to a thread by sebackman here
    They were inexpensive, from the Speaker Exchange.

    Quote Originally Posted by mortron View Post
    Looking forward to the progress on these. Are you going to have any controls or plates on the front baffle like the originals or just a big blue face?
    This system will not use passive crossovers and will be actively managed by the DBX360 from a tablet, so no L-pad type controls will go on the face. I think everyone, myself included, loves the period look of the classic JBL's with the controls! However, I may design a look-alike identification plate. I have to research who can take my artwork and print it on the correct backing which I assume is aluminum.

    Quote Originally Posted by Dr.db View Post
    I actually had a similar idea of using a different horn in a 4345-hybrid.
    What made you choose the little waveguide? What is it you donīt like with the genuine mid-lens?
    Since the system will be tuned with the DBX, I hope there is enough flexibility in using something other than the M2 waveguide (which itself requires DSP tuning). The STX825 received good reviews and its use simplified things a bit. No guarantees in any of this but seemed like a good approach. If it fails, I'll look for a plan B !

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    D2430K Protection

    I haven't decided at which values I'll start crossover tuning (290 & 800-1000 perhaps?) but did decide based on various LH posts and pos' excellent document to utilize a clone of the M2 D2430K protection circuit to restrict upward the frequencies directed to the D2. These will be mounted in a utility box behind the amplifier rack so they can easily be updated/replaced down the road.

    Internally, the 4345 will just have a wiring harness coming off the Neutrik connector that leads to each driver. The 2245 and 2123 will use 12 gauge and the D2 will use 14 gauge.

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  14. #14
    Senior Member grumpy's Avatar
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    Ha! I looked at the top portion of the pic and -very- briefly pondered what the coiled element could be... then
    recognized the spring-loaded heat sink for soldering (doh). Nice work.

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    Speakers are completed, next step will be ordering cabling then some preliminary testing.

    Assembly went well with only minor issues cropping up. I don't have much to add on top of the previous build threads but a) the Wrap-On insulation and spray adhesive worked out really well, and b) yes, T-nuts suck but on the tough ones a large c-clamp and scrap of wood will seat them very nicely. Oh, and once seated, chase the threads with the appropriate tap, in my case 10-24 and 1/4-20.

    Family portrait before mounting:
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    Two of the most important tools for use with 4345's - heavy moving blankets and appliance dolly!
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