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Shure M67 Mods
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RefD
on a wing and a prayer


Joined: 28 Aug 2004
Posts: 5993

PostPosted: Wed Oct 01, 2008 5:44 pm    Post subject: Re: Shure M67 Mods Reply with quote

RodC wrote:
RefD wrote:
a thought regarding the M67 being used for recording the Woodstock soundtrack: maybe they used a buttload of inline pads (those barrel thingies)?


Thats sorta what I assumed....

Images of a "buttload" of metal pads exiting some poor assistant's... run through my head.... Disturbing.... Shocked


geysering?
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Lost on side
gettin' sounds


Joined: 17 Dec 2004
Posts: 124

PostPosted: Fri Mar 20, 2009 2:05 am    Post subject: Re: Shure M67 Mods Reply with quote

Old Thread.
I have what may be a foolish question, being a real noob to DIY.

I know that "Germanium" is kinda a current trend/gimmick, but I was wondering if it would be possible, desirable, inconsequential, ill-advised, useless, too complicated, or a neat idea to change the the transistors in one of these to germanium transistors?
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Derrick
re-cappin' neve


Joined: 26 Nov 2003
Posts: 654
Location: MD/DC Metro Area

PostPosted: Fri Mar 20, 2009 3:13 pm    Post subject: Re: Shure M67 Mods Reply with quote

RodC wrote:
Heck they recorded woodstock with these, not sure how because that leads me to the biggest problem, distortion.


Hi Rod! Have you listened to the Who's set? I realize this is from Youtube, but all my audio and video has this same distorted characteristic. I think it's kinda cool in that it adds some energy and character, but I wouldn't do this for more then one song on a recording. Check it out:
http://www.youtube.com/watch?v=v5gBaCusDeY
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monty marc
audio school


Joined: 01 Sep 2009
Posts: 6

PostPosted: Tue Jun 01, 2010 3:58 pm    Post subject: Re: Shure M67 Mods Reply with quote

I work at a community radio station that has been using Shure M67 mic mixers forever on-air. We decided to implement them in our newly renovated production studios because we like the sound and everyone is used to them (it's almost impossible to install different equipment here). By doing some modifications they could now be used as mic preamps for recording. After re-capping the power supply we did the modifications according to Rodís instructions.

After doing the modifications, I didnít find it useful to have channel 1 left stock, and it appeared to be confusing for volunteer technicians using the studio that the 1st mic would have a master volume control yet not the other channels. So all channels were modified identically, none were left in the mix buss.

It occurred to me that I could remove the now- unused output transformer and use the resulting free space to accommodate a phantom power circuit. I happened on a designer/supplier of a very well made phantom power PCB (here is the main website: http://sound.westhost.com/. The circuit is Project 96A - P48V Phantom Feed Power Supply). The board cost around $20 including shipping and came with well designed instructions. Most of the parts were available at the local electronics surplus store but I had to order the 3 transistors on ebay. The total cost for everything relating to the phantom power came to around 40 bucks.

I followed the ESP instructions and mounted the parts and wiring on the PCB. I connected a 10mFd/63 volt cap and the two 6.81k 1% tolerance resistors to each xlr input jack (so 1 resistor each to pin 2 and 3 going to +48v, and the cap going from +48v to pin 1). Since the lo-cut filters had been disconnected from each channel, I used those switches for the phantom power to each XLR input. The output from the phantom circuit board was connected in parallel to each lo-cut switch, and each switch was then connected to the resistors/cap and xlr jack. Luckily the M67 I was using was in excellent shape and the switches were clean and fully operational.

ESP explicitly states that the phantom circuitís power supply has to have its own 30 volt ac transformer. The 30 volt transformer I found was small enough to fit right beside the unitís original step down transformer and allow room for the mounting screw to still fit. I drilled holes through the bottom chassis and used pop rivets to fasten the transformer. Once all parts and wires were soldered in the phantom PCB, I installed the board on the metal plate where the 2nd output transformer resided. I had to drill one extra hole in this plate and that was a little tricky. I then mounted the phantom power board there using plastic stand-offs and small nut/bolts.

I decided that since the master pot was now un-used, I could remove it and use that space to allow mounting of a switch that could be used to connect each chanelís output to the VU meter.
-I removed the master fader pot and replaced it with a 50k trimpot
-the green wire originally connected to the master volume control was connected to lug 2 of the trimpot, the yellow wire to lug 3 and I fastened lug 1 under the screw fastening the main pcb to the chassis. The trimpot lays flat and can be adjusted with a screw-driver. I found this helped to adjust the VU meter level measuring the channel 1 set to osc. and referenced on an external VU meter.

I then connected a wire from each individual ľĒ mic output to a separate pin on the 4 position switch. The common pole of the switch was connected to the channel one blue wire of the mix bus (any of the remaining unused blue wires could be used for this). So now, any of the 4 mic channels can be selected to read on the VU meter. I like these modded mixers so much that i bought 2 for myself to use in a remote recording kit.

outside


insdie showing phantom power circuit


vu selector switch wiring
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Nick Sevilla
speech impediment


Joined: 03 Mar 2008
Posts: 4453
Location: Los Angeles California USA

PostPosted: Wed Jun 02, 2010 11:20 am    Post subject: Re: Shure M67 Mods Reply with quote

Thanks for this RodC!

Now I can use my Shure M67 for cool things!

I will try to do the following to mine though : Keep the Mix buss unaltered, in order to be able to use it as a mixer as well.

How?

I'll tap the output of each channel POST gain knob, to it's own output connector, while leaving the rest of the wiring intact. It should not be too much of a problem.

Since this is an unbalanced circuit, it should be no big wiring deal.

Cheers
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Derrick
re-cappin' neve


Joined: 26 Nov 2003
Posts: 654
Location: MD/DC Metro Area

PostPosted: Wed Jun 02, 2010 1:02 pm    Post subject: Re: Shure M67 Mods Reply with quote

Won't that cause some loading?
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RodC
dead but not forgotten


Joined: 31 Dec 2004
Posts: 2039
Location: Right outside the door

PostPosted: Sun Oct 10, 2010 1:44 pm    Post subject: Re: Shure M67 Mods Reply with quote

Derrick wrote:
Won't that cause some loading?


Yes, however you can use a switched 1/4" jack to disconnect the circuit from the mix bus.

(Sorry for the late late reply, I just ran across this thread when searching for somehting else)
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changeng
audio school graduate


Joined: 09 Oct 2006
Posts: 23
Location: Los Angeles

PostPosted: Tue Oct 12, 2010 6:43 pm    Post subject: M267 insert???? Reply with quote

Sorry to go somewhat off-topic, but I don't know where else to ask this!

RodC or anyone in the know - how would you go about installing an insert jack into a M267? Using the mix buss, running that into a Shure M63 Audiomaster and bringing it back into another channel in the 267, I can get some neato tone shaping (the M63 has a 100hz pot, a 10Khz pot, plus hi and lo pass filters, with an output transformer - $20 bucks!).

But I'd like to have an actual insert so I can try it with normal EQs - any time I try other models, loading occurs and no one has fun. With the M63, mixing the two inputs of the 267 gives nice variety until the feedback starts.

I tried the 267 against a GAP Pre 73 (with the "TT" mod that Zen Pro Audio offers) using some dynamics and was shocked at how close the Shure came to the GAP. That was before finding a way to sneak the M63 into the mess.
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appreciative
audio school


Joined: 20 Oct 2010
Posts: 4

PostPosted: Mon Nov 29, 2010 3:59 am    Post subject: Re: Shure M67 Mods Reply with quote

With levels at 10 on the m67 is that "gain", or merely "no attenuation"?
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RodC
dead but not forgotten


Joined: 31 Dec 2004
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Location: Right outside the door

PostPosted: Mon Nov 29, 2010 8:44 am    Post subject: Re: Shure M67 Mods Reply with quote

appreciative wrote:
With levels at 10 on the m67 is that "gain", or merely "no attenuation"?


It's gain. If you look at the schematic, a 1k signal is injected at .1 mv, the output before the level control is 8.6 (Wired stock) I have never really checked the gain, but I'm sure its not x86.
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vivalastblues
steve albini likes it


Joined: 30 Jun 2008
Posts: 346
Location: Australia

PostPosted: Sat Apr 23, 2011 12:42 am    Post subject: Re: Shure M67 Mods Reply with quote

Maybe I should make a separate thread...but for anyone who has one of these and has racked them - where did you get the faceplate from? I can't find any images of it right now but I've seen them on eBay with an optional faceplate added.

If anyone can point me in the right direction that would be great. I arleady asked Shure and got no answer.

edit: kinda looks something like this I guess...
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ricercar.record
gimme a little kick & snare


Joined: 09 Oct 2009
Posts: 97
Location: Austin, Tx

PostPosted: Sun Aug 07, 2011 10:54 pm    Post subject: shure m67 mod, 48V supply Reply with quote

i've modded two of these units for myself and have been wanting to add the 48V Phantom Feed supply from ESP (Project 96A), similar to what monty marc has done.

However, so far I have been unable to find somewhere to buy a suitable (small in size) 30 VAC transformer that will actually fit in the box.
Does anyone have any possible recommendations for a transformer or for a good place online to buy them?

I know the transformer needed would be a 30 VAC secondary or a 15-0-15V secondaries (without using the center tap) and rated at 30 VA or above.
Each mic will draw about 10ma so needs to be capable of at least 40-50 ma for 4 mics, preferably more. I found this on mouser which would work perfectly,
http://www.mouser.com/Search/ProductDetail.aspx?R=166G30virtualkey54600000virtualkey546-166G30
.....unfortunately it's to large to be able to fit anywhere in the M67.

I have asked a few different people on here for some help/recommendations but no such luck so far,
so any helpful insight from experienced tombers would be greatly appreciated.

otherwise may just decide to use the 48V supply circuit in a different project.
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Matt C.
steve albini likes it


Joined: 15 Apr 2009
Posts: 399
Location: saint paul, mn

PostPosted: Fri Sep 23, 2011 10:40 am    Post subject: Re: Shure M67 Mods Reply with quote

I'm trying to transformer-balance the direct outs on my M67, but in my ignorance about transformers, I'm having a hard time finding one that's suitable. all the transformers i've found online are either very expensive (jensen, lundahl, etc) or have what seems to be terrible frequency response (unless i'm reading the specs wrong, i can't imagine 100Hz-12kHz being suitable for music...). they also need to be small since there's not a ton of extra space in the box. edcor seemed to be the closest i've found, but those might be too big. can someone direct me to where i might find something suitable? thanks!
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highvoltage
audio school


Joined: 31 Jan 2012
Posts: 9

PostPosted: Mon Feb 06, 2012 5:30 pm    Post subject: Re: Shure M67 Mods Reply with quote

So, what is the difference between the m267 and m67? In term of sound?
Does the older m67 sound more 'vintage'?

Just cause i live in Europe, and the m267 can work at 240v.
Its almost impossible to find an m67-2E here, and im really not good at modding stuff...
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Tavvish
audio school graduate


Joined: 25 Jan 2012
Posts: 12

PostPosted: Fri Feb 10, 2012 4:09 am    Post subject: Re: Shure M67 Mods Reply with quote

I have to say you are awesome for doing this, I really like how you had a sub-mission of making it cheap/easy, good man that is how I like my mods AND my women. stupid joke.
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