sandall

Ok, a couple of points. Powering - Yes, for a comms mic 1.5v should be fine. The capacitor - No, it's there to keep your 1.5v out of the mic preamp (there shouldn't be any phantom power* on a comms unit). Signal level - No, electret mics are usually much "louder" than the dynamic ones used for comms, so a transformer, a couple of resistors or a potentiometer are needed to get your mic level down, to match other mics on the system.

(*connecting electret mics to mixers with phantom power is a whole other topic, which gets discussed here from time to time).

I have no experience of bone-conduction mics, so no idea of the level they produce, but this might be of interest - https://www.vocal.com/voice-quality-enhancement/utilizing-a-bone-conduction-microphone/

Not really hung up on them - just old-fashioned Beebthink - if in doubt (or even if not) add a transformer (there's a LL/something for every occasion!)

12 hours ago, sunray said:

I can offer lots of advice on magic smoke, the real skill is getting the colour correct

Returning to the original question -

If your comms set specifies a dynamic mic it won't have phantom power, so won't kill your mic, though putting even 1.5v DC across a belt-pack mic input MIGHT be problematic.

The quoted 1.5v mic power will be a minimum value. The capsule is likely to be generic Chinese, & will probably be happy with anything from 1.2v to at least 5v. I suggested using AA or PP3 batteries, but stand-alone miniature mics are more likely to come with alkaline or lithium button cells these days.

I'm curious as to how you make your distinction between "nuts and bolts theory" & "electronics understanding". 

If it helps, I can send you a simple suggested circuit, or maybe sunray can offer you a practical solution?

It's for comms & emulating a 200R dynamic mic for level & impedance, so I think I'd stick with the transformer. I have some of those original Eagle mics somewhere, but not sure of their relevance here.

I would suggest using a transformer for your impedance matching. Electret mics are generally much higher level than dynamic mics, so a small 1.5k to 200R step-down transformer will solve both problems. A couple of AAs or a PP3 via a resistor (anything from 2k to 10k, chosen to give about 2v at the mic) & a small capacitor to isolate battery volts from the transformer.

We seem to have strayed a long way from recommendations for a fan to keep cedd cool.

1 hour ago, Jivemaster said:

POSSIBLY partially  a deliberate delay to reduce the chances of feedback when a mic is pointed at a speaker.

POSSIBLY, but doesn't everyone have a "feedback destroyer" in their rack to keep them awake (or left bypassed if they don't want to be kept awake)? I suspect Jon has the answer.

Maybe it's time to bin the offending bit of cable & accept that the gremlins will always win?

3 hours ago, GaryNattrass said:

It's a D25

Good call⭐. I suspect it might have been lying around on someone's workbench at TFS. I've got a couple of D14s here, which are a bit smaller & less robust, one of which has been repurposed as the innards of a dead AXBT.

Interesting, following this thread, that until today the blind & deaf have barely been considered; those with mental issues not at all. A huge number of us have disabilities of some sort; if we want to do something beyond our physical abilities we either have to find a work-round or decide it's not practicable (I've got all my fingers & toes, but I'm never going to be a concert pianist, but that's ok). There are backstage jobs that people with mobility issues can do well, without endangering others, e.g. DSM, lx or sound op, maybe even follow-spot, but pretending that everyone can do everything if only enough money is thrown around......?

The little 4" hand-held jobs shift a reasonable amount of air & last up to 9 hours on a charge. A bulldog grip or gaffer-clamp would hold one where you want it.

3 hours ago, kgallen said:

Could well be junk though I guess (but it is for a pub...!) https://www.ebay.co.uk/itm/........

Would treat with extreme caution. Illustrations don't match descriptions & the same item is offered as a replacement for totally different capsules.

6 hours ago, kerry davies said:

West London might suggest a local "acquisition" for these two?

Couldn't possibly comment🙂, but the chap who originally hung them worked at Ealing Studios & the venue used to be littered with ex-BBC speakers from "Redundant Plant" in Chiswick. Good shout for the M8; maybe they were used by film recordists at one time. I had assumed the lower one to be a Coles or Reslo ribbon, but if you are right about the M8 it ought to be a cardioid.

38 minutes ago, Jivemaster said:

If they need hearing assistance then they likely have an NHS audiologist. If so, then that person will be able to assist in your search for  wisdom. 

If you live where I do you may find your NHS audiologist has been replaced by an untrained Specsavers machine-operator🙁

35 minutes ago, Ynot said:

QUALITY mounting there...

A plastic mic-clip (just out of top of picture),a K& M boom & a hook-clamp onto a bit of scaff completed the mounting (not a safety in sight)!

Clue - the lower mic will be a ribbon.

One for the "seniors". Can anyone ID these two, rigged in an MS setup for stereo show-relay?

Looks like a MD835 cardioid (most likely), but could also be a MD845 super-cardioid or ME865 capacitor super-cardioid. Should be labelled at the front & there should have been a coloured ring between the basket & the mic body - Green for 835, blue for 845 or red for 865. I'm guessing (but only guessing, as I don't have an e835 to hand) that you could do a swap from an 2nd-hand e835. Lots on fleabay, but beware of the guy from Latvia selling "replacement" capsules that are a totally different shape. 

Unfortunately the AudioFires (which were unbeatable if you didn't want all the bells & whistles that modern soundcards come with) came as a package with SFX, which AFAIK is still Windows-only &, as Timeline still seem to be giving it away, probably not long for this world. Still, as you suggest - problem sorted.

12 hours ago, jamesperrett said:

the D630 uses the O2 Micro chipset for Firewire which is one of the ones I tried without success

Ok, thanks James. Probably time to abandon the idea, though I might persevere enough to see what a PCMIA adapter makes of audio (if anything). That's a useful site; I looked up my old C840 for interest, but the mini-spec doesn't mention Firewire or USB ports.

12 hours ago, jamesperrett said:

I wouldn't use the built-in Firewire on an old Dell laptop for audio. The one's I've used don't have a TI firewire chip and, while they may recognise the interface, you are unlikely to be able to transfer any audio without strange noises. Older Lenovo laptops are likely to be more successful as they tended to use TI Firewire chips. I also have an old Acer laptop with a TI chip which works well with Firewire interfaces.

Interesting; something I hadn't considered. My only direct experience with using Firewire was years ago, editing from DV with Premiere on a Dell Latitude C840.  Just out of curiosity I may have to borrow one of the AudioFire cards to see if my D630 will talk to it. The original problem has now gone away, as they are going to buy another Scarlett to keep as an emergency spare, but thanks for all the suggestions

A bit of background; the amateur theatre I'm still involved with has replaced its 12-channel Echo AudioFire cards with Focusrite Scarlett 18i20s (with an extension card for the main house) -  total overkill for our needs, but hey, that's progress, & Echo got out of audio a while back, so there's no support for the AudioFires. Someone is taking a show to Brum next week & wants to take one of the Scarletts out of a rack, which seems a really, ready bad idea, so the suggestion was to make up a travelling kit with a laptop, one of the AudioFires & (as we've found that modern laptops don't seem to come with 1394 ports) a USB - 1394 cable. Unfortunately, like many electronic items on the well-known shopping sites, they don't work, so it looks like the options are buying or hiring another Scarlett, or buying a cheap refurbed Dell to use with one of (beautifully simple) AudioFires.

I've been asked to connect an old Firewire soundcard (Echo AudioFire-12) to a laptop that only has USB sockets, to make up a travelling kit. There are lots of USB-Firewire leads out there, but apparently they only work with Sony cameras. I've suggested buying a refurb'd laptop like a Dell D630, which has both a Firewire socket & an ExpreeCard slot, but does anyone have better ideas?

Also worth checking CPC for budget headsets. I wouldn't be surprised if many of the budget branded mics all come out of the same factory.

Manual at https://www.terralec.co.uk/Portals/54/product/images/prde5d98478-1da8-4003-9871-68f9ce0f7fb4.pdf 

Only suggestion for resetting is unplug from mains, & wait 30".

Getting your receivers or aerials nearer the action might be a lot cheaper, but no reason to suppose these won't do the job.