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Matthias Richter

Berlin cart

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Hi there,

first day off on my shoot with my new cart ...

shark antennas Sennheiser for Zaxcom wireless

omni antenna Sennheiser for Intercom

Monitor

Power distribution (self made, RF filtered, single fused)

Zaxcom RX 4900

SD 744T with CL1 Interface

Sennheiser EW 300 (Stereo Transmitter for Intercom, Boom / Video, Dir, Script, Prod)

Mixer CS 208D

Keyboard for SD 744T

Battery (12V/24AH) in Pelicase with Power supply (13.8V) when AC is available

12HE and 8HE SKB lookalike cases

20" wheels with quicklock axes that snap into a pushwheel connector (click and pull)

apart from a RF issue with my Zaxcom wireless (see ramps) everything is cool.

Matthias

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Good looking cart and nicely outfitted. As everyone knows, I have built a few CASE based type carts in the past but have always found things that I don't like (even though all of these have been my own design so I have no one to blame). Seeing all of these new carts (and most seem to be built around a case) has given me renewed interest in looking into building another cart.

Thanks for putting up the images and good luck working with your new cart.

Regards,  Jeff Wexler

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I wanted to have all my gear fit into the top case so I can take that of for a small set where I need to hide in a corner or something. Right now I only take the bottom one for the battery and a pelicase with my wireless stuff. But that is just for rolling around so my boomop doesn`t need to carry so many cases.

That way the whole cart isn`t too heavy and two people can bring it to the 4th floor of an old Berlin-style house without getting exhausted.

The whole cart even fit into a small Renault Kangoo just by taking of the big wheels (which is done in 3sec).

Last year I spent 3 month shooting in Kenya. I don`t know if that would have been alright with an open cart - with all the sand and dust flying around.

The SKB drawers / sliders are good but you have to find a solution to hold your cables up. Otherwise they gonna fall into the gap between the slider and the back of the slider rackmount - you won`t be able to push the slider back in properly.

I have done it with some rubber-bands. They hold the cable in place and if you pull out the shelf they will expand.

My power supply is "JW" style actually - it was described on ramps. I have build it myself. Very easy to accomplish and it seems to work just perfect - thanks Jeff.

Regards, Matthias.

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thats a two position slider ;-) its just velcro. I can velcro it to the edge of the mixer and for transport I velcro it a little bit further in onto the SKP fluffy side

Oh, I see--the mixer is sitting up on the edges of the sliding shelf, leaving room underneath.  Simple and clever.  What is the box just under the 744T?

Re "case carts" vs open frame etc:  I've always liked everything out in the open for ease of repatching, but am coming around more towards the style of Scott Farr's new rig (if I ever get around to changing anything....)  in order to protect more flaky connectors like FW and CL1 and minis coming in and out of the SD recorder.

Philip Perkins

Philip Perkins

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that box is the stereo (or lets say 2ch) transmitter Sennheiser SR 300 G2. Its for feeding the boomOp(s) with signal and private line on one channel and director, script, etc on the second channel.

Receivers are called EK 300. For bag mode I`ve got a SKP 100 which is a single-channel transmitter.

The mixer didn`t fit inside the slider by 2mm. So I have made an U - profil that is velcroed to the slider / mixer. An additional feature is the now existing space underneath the mixer which is just perfect for the keyboard (or a folder if one doesn`t have a keyboard)

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20" wheels with quicklock axes that snap into a pushwheel connector (click and pull)

Well done cart.  I'm starting to think about the case cart design myself.

Would you mind posting some pictures of the back of the cart, specifically the quicklock axel (?) and pushwheel connector?  Love to see what that is...

~PWP

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Well done cart.  I'm starting to think about the case cart design myself.

Would you mind posting some pictures of the back of the cart, specifically the quicklock axel (?) and pushwheel connector?  Love to see what that is...

~PWP

+1

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Jeff, can you elaborate on the "JW Power Supply"?  I must have missed that.

Philip Perkins

The simplest way to describe the cart power supplies I have been building for the last 10 years or so is to let you know the main components: sealed lead acid batteries and regulated DC power supply --- it's that simple. No charge circuit, no standby UPS stuff, no inverters, etc. I use either linear power supplies (with transformers and available new or through surplus) or switching power supplies (more on the type later) that when plugged into AC (usually 90 volts to 240 volts) put out 13.8 volts DC at around 10 amps. This is connected to the battery and then the equipment, the load, is also connected to the battery. When plugged into AC, the DC from the power supply floats across the battery keeping a fully charged battery, fully charged. When the equipment is powered up and drawing considerably less than 10 amps, the battery stays charged and everything is happy. If there is no AC or the AC gets pulled accidentally (does that every happen?) the equipment is still getting DC but now off of only the battery. There is no noise, no charging circuit to introduce any trouble, the equipment is quite happy to be powered off the battery. When the AC returns, whatever has been drawn off the battery is replenished. It is an elegantly simple system that has been 100% reliable for the last 10 years or so.

There are a few caveats: if you use switching power supplies you must purchase supplies that have a low noise and low AC ripple spec (but most of the medical grade supplies work very well in this respect) and they must have an amperage rating that is greater than the maximum current draw you have will all equipment powered up. Secondly, you must choose a battery type that is suitable for constant current across and this type is generally the sort that is used in backup lighting systems, alarm systems, any place where the battery is happy in a stand by mode. Then you choose how many amp hour capacity you want based on how long you want your equipment to run off the battery alone. In my case I have 35 amp hour battery which will run everything on my cart for 6 hours. Lastly, you must start out with fully charged battery so that means having a conventional battery charger available. The float system relies on having a fully charged battery so if the cart has been sitting around for a long time and the battery is discharged, it should be fully charged before using this system in production.

All of this stuff is housed in some appropriate case or chassis box with everything fuse protected and multiple 4-pin XLR outputs as needed for distribution. On my cart there is one connection to this box and then my cart is internally wired with several DC connection points in the proper places for the equipment in use. I also made the wiring from all these connection points "home runs" meaning there is a continuous wire from each connection point back to the power supply. Rather than looping through each connection point this seems to cut down on interaction amongst the equipment.

Regards,  Jeff Wexler

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here some (mobile phone) photos of the quicklock system. To stabilise the somewhat wobbly case-walls I have four crossbars in the bottom case.

I spare the try to explain, but I do hope that the pics will make things clear ...

Matthias

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one thing you won`t see on these pics: if you press the black thing in the middle of the wheels a locking mechanism will loose and you can pull the wheel with its axis out of the connector (alright I will have some photos 2moro ;-)

Matt

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Thats a very nice cart you have put together, my compliments, you realise you have given me ideas... I am intrigued to know if you built or bought the rack cases and how you joined them together.

Rob Stalder

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Thanks for posting your cart information, I've started building one myself. I was inspired by Scott's commercial work sound cart to get started.

http://www.jwsound.net/SMF/index.php?topic=1425.msg9264#msg9264

I was thinking of buying a readymade one at some point, RastOrder perhaps but I like the idea of a rack case type cart which can be fairly lightweight etc.

I'm very grateful and of course fascinated to see the different ideas people have come up with and if I manage any innovation myself I promise to return the favour and post it.

Coincidentally I had seen quicklock wheels similar to yours also made in Germany perhaps by the same company and used for a harp cart (a friend of mine repairs harps) and thought 'I must investigate that further for my cart' but you've beaten me to it!

So where did you get your '20" wheels with quicklock axes that snap into a pushwheel connector' please? and the strengthening bars inside the case?

I think it could be very useful to have the option to quickly remove/put back the wheels.

many thanks.

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I have been looking all different kinds of carts on the net as well and was taken a lot of good ideas out of it. So that was my motivation as well to put my solution back onto the net-community.

I`ve got the wheels from my local bike-store. Its from:

http://www.croozerdesigns.com/

The matching connectors are from a local push wheel repair service but you might wanna check:

http://www.acelo-dmtc.net/xanario/index.php?xC=Hub_-_axle_receiver_bearing&sessID=19a8a922e6b7cfa46bc381ee94492a78

The bars are just ordinary bars with thread all the way around / along from my department store. But because its just M6 thread and not stabile I have on two of them a matching tube on top. Just cut of a bit so you can fix the two way screws on the sides.

Joining the two (ebay) cases together is another simple but excellent solutions ;-) Because the cases have the matching thingies on top / on the bottom you just staple them and then have that construction secured with an ordinary  tension-fastener or whatever this is called in English.

Matt

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I have 2 SKB cases that are very similar in size and configuration to the cases you have used. I have been planning on using them to build a Case-based cart (if I ever really decide to go through with building that kind of cart). I had considered using just the lower case itself to attach wheels, front and back, rather than going the route others have done --- build a substantial base (aluminum or steel) with wheels and place the case onto the base. It looks as if you did it the first way, the lower case IS the base with the wheels. Has this worked out okay --- is the case rigid enough with that you did with metal bracing, axle and so forth? I was always worried that if the wheels and everything were mounted right to the case, the case would have too much flex and strain.

-  Jeff Wexler

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I should have an english version of the text, shouldn`t I?

I have done 3 features with my new cart and it has been working really good. After the first shoot I added the wooden block inside the lower case as I felt I could need a bit of extra strenght. But that was based on feeling only. The wheels performed really good even on cobble stones.

In the beginning I thought about an U-shaped frame like on another cart here in the forum (http://www.jwsound.net/SMF/index.php?topic=1051.msg7912#msg7912) but the metal-company was too busy and I had to start my shoot so I went this route instead. It feels like a insurance that I could go to the U-profile version if necessary.

Matthias

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Looks great.  For wireless, is that a rack mount Zax RX?  I hadn't seen one before--4 receivers in one?  Since you are working in Europe I had wondered about rolling over cobble-stone streets-- I'm glad the big wheels are working.  Do you typically lean the cart back and go 2-wheel over the cobbles or can your front wheels handle that too?  Do you ever use a laptop--if so where would you put it?

thanks for the new pix

Philip Perkins 

(wishes this forum had been around when I built my first carts....)

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Philip Perkins 

(wishes this forum had been around when I built my first carts....)

Isn't that the truth! One of the great things about the Internet Age is the easy sharing of all of these experiences, and the linking to companies with all the clever supplies to build these things, and on and on. I have learned so much from all these postings --- and again, so pleased that we have such a diverse and international group of people here.

Good show!

-  Jeff Wexler

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Matthias, thanks for the new pictures.

just a note: you should have further separation between antennae, otherwise they work as one (coupled). But avoid separation being equal to 1/2 (half) wavelength.

you can use this to calculate: http://www.csgnetwork.com/freqwavelengthcalc.html

for instance, I use 51~56 cm separation for US blocks 21 and 22 (537~589 MHz), that is, the full wave wavelength

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Philip,

that`s the Zaxcom receiver RX4900. It`s 4 stereo-receiver in a 19" 1HU unit. works great but I have to get some portable units for bag mode.

Unless working on a studio floor I always lean the cart back when wheeling around. Thats why the handles are not straight but ankled so I get a good balance. But with the little wheels on the front you can `dance`on the spot!

But you got me on the laptop - that`s still on the to do list. I might add a motu traveler that will fit into the case just underneath the rx4900 (the ew300 will move behind the SD744). But I will need a swing arm/holder for the laptop.

Fernando,

you absolutely right with the spaced antennas - another thing on the to do list.

but isn`t it fun anyway that all mixers are always improving their baby? ;-)

and Jeff,

it`s a great show indeed!!

Matthias

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did a bit of modification to my cart. Since my new Fusion 12 needs a bit more space I have modified 2 sliding shelfs from SKP to selfmade aluminium versions.

That created a lot of hight so I could lower my monitors to a fixed position where the rack-door can be closed. The monitors are fixed with small arms so I can swing them aside to get access to the room behind (used for comtek-headphones).

A new DC-powerdistro (looks like a cockpit switchplate) gives me a fast check what gear got power or which fuse might have been blow up.

Matthias

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