Sound devices sd-302 mixer

Bob Hart · July 20th, 2014, 07:44 AM

I wonder whether the original scheme may have been to use two batteries like the Mix-Pre but the power draw from three phantom mikes might have been too much. The position of the internal tail for the power from the battery tube to the PCB is about right for a two-battery arrangement.

Towards the 3 x XLR socket input panel, there remains no space to extend the battery tube internally to retreat the tube internally into the casework. Those sockets occupy a lot of real estate.

To extend the case deeper or thicker from to back would not have been convenient except at a raised price for custom parts, long case and side ends unique to the SD-302 which are a near-standard except for hole positions.

The case lengthwise is a single aluminium extrusion which appears intended to be common for the Mix-Pre, SD-302 mixers. The only finishing operation necessary is the actual parting operation for each case length if the right tool is used.

Altering the design for a two-by-one or two-by-two shorter and broader battery pack would only be possible by a unique added operation of cutting a hatch in the bottom surface and adding a lid, severely weakening the structure and adding more risk of fluid intrusion wicking in when set down upon a wet surface. This assumes that the batteries might just fit as two rows. I don't think there is enough real estate in there to accommodate two battery rows placed side-by-side plus wall thickness of the internal pack which would also have to be a slightly offset arrangement.

This would constitute six added unique parts. The extended battery-tube arrangement, whilst odd-looking, is a better, simpler and more reliable solution.

Jim Andrada · July 20th, 2014, 11:37 AM

Good points Bob - I've never had a mixPre so wouldn't know if the case is the same length, and commonality could be the reason - but it really DOES look strange and the effective overall width is dictated by the width of the case plus the projection of the battery compartment.

Cutting the case extrusion to a different width is trivial so that's not it.

Not a big deal, but I always scratch my head about the strangeness of it. It looks like an engineering solution as opposed to a marketing solution. (I'm in marketing by the way) - or an afterthought if as you suggest two batteries turned out to not be enough.

Bob Hart · July 20th, 2014, 01:19 PM

The maincase extrusion on the Mix-Pre is cut to a shorter length. The two-battery tube cap also sticks out but not as far, nearly flush with case.

If they had re-engineered the SD-302 case wider ( extrusion cut longer ) to allow the battery tube to be buried, the top panel with all the controls etc., would also have had to be extended. This would create a bit more rel-estate on the top panel for the headphone socket to be relocated to the more familiar position facing upwards and use of a full size phono plug.

All these internal pigtail leads may also be common to a broader product range. To remake them longer just for the SD-302 might make for another added cost.

All internal leads from one or the other of the end panel sockets to PCB ( or both sets if the revised arrangement was to be nicely centred ) would have had to be lengthened or the PCB extended. As you suggest, it seems an engineering solution which was the least complicated and least costly to implement was chosen.

From what I can see, if external power was to be the permanent sole option for an owner/operator, the battery tube could be eliminated entirely without disabling the mixer and the hole capped off with a suitable grommet.

I think the balance of convenience comes down on retaining the battery tube for that occasion when the big battery dies or some clown severs the power lead by forgetting to secure the battery in the Portabrace and it drops it with a thud on the stretch of the cable or damages it in a car door or some other catastrophe like forgetting to pack it and only finding out 300km up the Amazon or wherever.

FOOTNOTE: In the thought there might have been some residual bloom well hid somewhere going hydroscopic when the machine was cold and creating a conductive path, I cut down some silicagel cylinders from vitamin bottles and put them in the case to pick up any humidity within the case. It did not work, so it would seem, that the failure-to-initiate problem when cold, may be electro-mechanical or component related. It will need to fly home for a fix when I can afford it.

Tom Morrow · July 25th, 2014, 11:51 PM

For portable use in a sound bag every inch matters.

The Xlr cables plugged in next to the battery tube extension mean that the battery tube does not use any extra bag space. This is it's magic. But if you extended the whole case to flush with the battery tube then the XLRs and top panel would stick out making for a significantly bulkier and heavier mixer and bag.

Jim Andrada · July 26th, 2014, 10:15 AM

Good point Tom. I always use mine in a "desktop" application so portability (for me) is more about ease of schlepping it to the location than ease of carrying it in a bag.

Bob Hart · July 26th, 2014, 06:03 PM

Tom.

That detail did not even remotely enter my head. But then I was never head of the class in the observational stakes.

July 20th, 2014, 07:44 AM	#16
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	Re: Sound devices sd-302 mixer I wonder whether the original scheme may have been to use two batteries like the Mix-Pre but the power draw from three phantom mikes might have been too much. The position of the internal tail for the power from the battery tube to the PCB is about right for a two-battery arrangement. Towards the 3 x XLR socket input panel, there remains no space to extend the battery tube internally to retreat the tube internally into the casework. Those sockets occupy a lot of real estate. To extend the case deeper or thicker from to back would not have been convenient except at a raised price for custom parts, long case and side ends unique to the SD-302 which are a near-standard except for hole positions. The case lengthwise is a single aluminium extrusion which appears intended to be common for the Mix-Pre, SD-302 mixers. The only finishing operation necessary is the actual parting operation for each case length if the right tool is used. Altering the design for a two-by-one or two-by-two shorter and broader battery pack would only be possible by a unique added operation of cutting a hatch in the bottom surface and adding a lid, severely weakening the structure and adding more risk of fluid intrusion wicking in when set down upon a wet surface. This assumes that the batteries might just fit as two rows. I don't think there is enough real estate in there to accommodate two battery rows placed side-by-side plus wall thickness of the internal pack which would also have to be a slightly offset arrangement. This would constitute six added unique parts. The extended battery-tube arrangement, whilst odd-looking, is a better, simpler and more reliable solution. Last edited by Bob Hart; July 20th, 2014 at 07:53 AM. Reason: error

July 20th, 2014, 11:37 AM	#17
Jim Andrada Inner Circle Join Date: Feb 2007 Location: Tucson AZ Posts: 2,211	Re: Sound devices sd-302 mixer Good points Bob - I've never had a mixPre so wouldn't know if the case is the same length, and commonality could be the reason - but it really DOES look strange and the effective overall width is dictated by the width of the case plus the projection of the battery compartment. Cutting the case extrusion to a different width is trivial so that's not it. Not a big deal, but I always scratch my head about the strangeness of it. It looks like an engineering solution as opposed to a marketing solution. (I'm in marketing by the way) - or an afterthought if as you suggest two batteries turned out to not be enough.

July 20th, 2014, 01:19 PM	#18
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	Re: Sound devices sd-302 mixer The maincase extrusion on the Mix-Pre is cut to a shorter length. The two-battery tube cap also sticks out but not as far, nearly flush with case. If they had re-engineered the SD-302 case wider ( extrusion cut longer ) to allow the battery tube to be buried, the top panel with all the controls etc., would also have had to be extended. This would create a bit more rel-estate on the top panel for the headphone socket to be relocated to the more familiar position facing upwards and use of a full size phono plug. All these internal pigtail leads may also be common to a broader product range. To remake them longer just for the SD-302 might make for another added cost. All internal leads from one or the other of the end panel sockets to PCB ( or both sets if the revised arrangement was to be nicely centred ) would have had to be lengthened or the PCB extended. As you suggest, it seems an engineering solution which was the least complicated and least costly to implement was chosen. From what I can see, if external power was to be the permanent sole option for an owner/operator, the battery tube could be eliminated entirely without disabling the mixer and the hole capped off with a suitable grommet. I think the balance of convenience comes down on retaining the battery tube for that occasion when the big battery dies or some clown severs the power lead by forgetting to secure the battery in the Portabrace and it drops it with a thud on the stretch of the cable or damages it in a car door or some other catastrophe like forgetting to pack it and only finding out 300km up the Amazon or wherever. FOOTNOTE: In the thought there might have been some residual bloom well hid somewhere going hydroscopic when the machine was cold and creating a conductive path, I cut down some silicagel cylinders from vitamin bottles and put them in the case to pick up any humidity within the case. It did not work, so it would seem, that the failure-to-initiate problem when cold, may be electro-mechanical or component related. It will need to fly home for a fix when I can afford it. Last edited by Bob Hart; July 20th, 2014 at 01:24 PM. Reason: error

July 25th, 2014, 11:51 PM	#19
Tom Morrow Major Player Join Date: Feb 2011 Location: San Francisco, CA Posts: 416	Re: Sound devices sd-302 mixer For portable use in a sound bag every inch matters. The Xlr cables plugged in next to the battery tube extension mean that the battery tube does not use any extra bag space. This is it's magic. But if you extended the whole case to flush with the battery tube then the XLRs and top panel would stick out making for a significantly bulkier and heavier mixer and bag.

July 26th, 2014, 10:15 AM	#20
Jim Andrada Inner Circle Join Date: Feb 2007 Location: Tucson AZ Posts: 2,211	Re: Sound devices sd-302 mixer Good point Tom. I always use mine in a "desktop" application so portability (for me) is more about ease of schlepping it to the location than ease of carrying it in a bag.

July 26th, 2014, 06:03 PM	#21
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	Re: Sound devices sd-302 mixer Tom. That detail did not even remotely enter my head. But then I was never head of the class in the observational stakes.