Topic: Just bought a Shure FP24 - some questions

[voltronic]

I thought this was a good deal, so I jumped on it:
http://www.ebay.com/itm/Shure-FP24-Audio-Mixer-/111451229883?pt=US_Live_Studio_Mixers&hash=item19f302cebb&nma=true&si=VM96%252FLomMniTgxYlwLusuqD1DwQ%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

Now I have a few questions:

1. Is this in fact a good deal considering the probable age of the unit?  From what I read these were made under the Shure label up until 2002.
2. Even if it is in perfect working order, should I send it to Sound Devices for a once-over?  (again, because of age.)  If anyone has done this before, how is their service?
3. I'll be using this into an M10, and it seems like the typical connection that way is with the 1/8" Tape Out.  Is it possible or preferable to use the XLR line outs with a dual XLR to stereo 1/8" Y-cable to have the full 66dB of gain?  Or would unbalancing those outputs cause other issues?  This would be a very short cable run.  http://cdn.shure.com/user_guide/upload/860/us_pro_fp24_ug.pdf
4. What is a good external battery to use with this?  I'm going to try AA Li-ion rechargeables first and see how long I can run it.  If I can get 2.5 - 3 hours I won't need the external.

Thanks for the advice and experience!

[chinariderstl]

My two cents, for what it's worth.

I bought a real nice used Mixpre from the Yard Sale.  I sent it to Sound Devices for a once over.  They replaced a few minor things, certified it, and had it shipped back in a week, all for under $160.  I would highly recommend it if you have the cash.

I always run Tape Out into my PCM-M10 (line in).  I think the XLR's are pretty hot.

I power the unit with an Initial RB-270 9V DVD battery.

http://www.overstock.com/Electronics/Initial-RB-270-Portable-DVD-Player-Rechargeable-Battery/3985593/product.html

I had Ted make a Hirose > 9V power cable for me.

Also, a little bit of gain goes a long, long way on those devices.

There's also a thread, might be a Mixpre thread, that details how to sync levels (for lack of a better phrase) between the Mixpre/FP24 and the PCM-M10.  I think DigiGal wrote it up.  I can find it if need be.

[voltronic]

My two cents, for what it's worth.

I bought a real nice used Mixpre from the Yard Sale.  I sent it to Sound Devices for a once over.  They replaced a few minor things, certified it, and had it shipped back in a week, all for under $160.  I would highly recommend it if you have the cash.

I always run Tape Out into my PCM-M10 (line in).  I think the XLR's are pretty hot.

I power the unit with an Initial RB-270 9V DVD battery.

http://www.overstock.com/Electronics/Initial-RB-270-Portable-DVD-Player-Rechargeable-Battery/3985593/product.html

I had Ted make a Hirose > 9V power cable for me.

Also, a little bit of gain goes a long, long way on those devices.

There's also a thread, might be a Mixpre thread, that details how to sync levels (for lack of a better phrase) between the Mixpre/FP24 and the PCM-M10.  I think DigiGal wrote it up.  I can find it if need be.

Thanks for the recommendations!  Hmm, $160 is probably quite reasonable for this kind of service, but more than I want to spend right now so I think I'll wait and see if something is broken first.

I think I've seen that post from DigiGal you mentioned before, but can't locate it.  I found this other thread on fp24 settings: http://taperssection.com/index.php?topic=161058.0

[chinariderstl]

Here's the thread.

http://taperssection.com/index.php?topic=165688.msg2084122#msg2084122

[voltronic]

Thanks.  The other thread I found on the FP-24 settings said to calibrate to -16 rather than -20 so I'm not sure the two units are identical in the output levels.

[DSatz]

I have an FP24 which I sent to Sound Devices for checkout and repair this May. They replaced the return-level pots and the limiter threshold pots, "confirmed unit is at production spec, passed all factory bench tests" and the total was $76.76 plus shipping. Turnaround time was about two weeks.

I also have an MP-2 which evidently needed more attention: $128.65 + shipping.

Both units were sold to me in supposedly "like new condition" and I really don't think that any conscious deception was involved. In my experience this is a typical, normal outcome of buying used recording equipment.

--In general there's no technical advantage to be gained by using a balanced output to drive an unbalanced input, unless you balance that input (and then there's a huge advantage to driving it from a balanced source rather than an unbalanced one).

In any case you do NOT want to use the XLR outputs of an SD preamp to feed an M10 or any other device with consumer-type aux inputs, because the gain of the FP24 is too high for that. Even with professional recording equipment, when I use the FP24 or MP-2 I generally have to set the recording equipment to its least sensitive setting and run the SD preamps distinctly below the halfway mark within their gain range. And there are plenty of people who record louder music than I do, as well as some microphones that put out hotter signals than mine put out.

--best regards

[tim in jersey]

If you do send it in for service, have them check/replace the spring in the battery compartment. Some of the earlier units could not run on NiMh rechargables because the + end of the batteries are a little different than alkalines.

In the mean time, you can also do a mod to the rechargable batts. Basically take an exacto to the shrink wrap along the ridge line near the + end of the battery and pull off the little wafer near the tip. The battery will now make contact with the internal spring and you should be good to go.

Photos to make it easier to understand: https://plus.google.com/photos/114775014104918758740/albums/5511784095874887345

[voltronic]

In any case you do NOT want to use the XLR outputs of an SD preamp to feed an M10 or any other device with consumer-type aux inputs, because the gain of the FP24 is too high for that. Even with professional recording equipment, when I use the FP24 or MP-2 I generally have to set the recording equipment to its least sensitive setting and run the SD preamps distinctly below the halfway mark within their gain range. And there are plenty of people who record louder music than I do, as well as some microphones that put out hotter signals than mine put out.

--best regards

This is good to know, thanks.  Do you know what level the FP24 outputs over the Tape jack versus the level of the XLR outs?  I'm still trying to figure out if the M10 should be set to read -16 or -20 with the FP24's test tone output.

[voltronic]

If you do send it in for service, have them check/replace the spring in the battery compartment. Some of the earlier units could not run on NiMh rechargables because the + end of the batteries are a little different than alkalines.

In the mean time, you can also do a mod to the rechargable batts. Basically take an exacto to the shrink wrap along the ridge line near the + end of the battery and pull off the little wafer near the tip. The battery will now make contact with the internal spring and you should be good to go.

Photos to make it easier to understand: https://plus.google.com/photos/114775014104918758740/albums/5511784095874887345

I heard of this when researching the unit, but your pictures make this much more clear - thanks!  They're the same batteries I have now and they're a bit old so I don't mind taking the knife to them.

[Cheesecadet]

Also, be aware that oscillation can occur with many mics if you try to use all the gain possible.  I never have to go above halfway on the gain knobs on my unit.  I actually usually run my knobs at about 9 O'Clock-ish with my M10 recording level @ 4.

[DF81]

The XLR outputs on the FP24/early Mixpre's don't play well w/ most current portable recorders (see the details/thread on pre-2002 Mixpre's)  So you want to use the tape output.  It's a nice preamp!

[ts]

I use Lithium AA's in mine set at 15V for powering AKG Naiant couplings and it runs all day. I had it set at 48V by accident once and it still ran all day. 10 - 12 hours.

[bryonsos]

It's in the other thread, but worth repeating here: attenuators are your friend. I use Naiant 24db ones with my Avensons and 3 Zigmas, and have the gain set ~11:00 most of the time.

[voltronic]

I use Lithium AA's in mine set at 15V for powering AKG Naiant couplings and it runs all day. I had it set at 48V by accident once and it still ran all day. 10 - 12 hours.

Really?  That's really impressive.  I'm mostly going to be running 48V.  Which batteries do you use?

[voltronic]

I have an FP24 which I sent to Sound Devices for checkout and repair this May. They replaced the return-level pots and the limiter threshold pots, "confirmed unit is at production spec, passed all factory bench tests" and the total was $76.76 plus shipping. Turnaround time was about two weeks.

I called Sound Devices service department today, and the very nice person I spoke with said that $75 is the minimum bench fee for anything that comes in.  It seems that they were more than reasonable on your parts!

I think I'm going to hold off on sending it in for now until I actually get my hands on it myself.  Being that it's an eBay purchase, I want to make sure nothing is obviously broken or different than advertised in the event I would need to get my money back.

You and others here have successfully dissuaded me from using the XLR outputs with my M10.  I had mistakently thought the FP24 had a mic/line level switch on the XLR out, but it seems that's only in the later versions.  I'm curious - what equipment DO you tend to run off of those outputs?  I'm thinking of pro-level gear meant to accept that kind of level, and nothing portable springs to mind other than Sound Devices own mixers and recorders which already have their own preamps. 

A couple of the concerts I record every year are also covered by our local TV station, who has great video production but terrible audio.  (As in, one SM58 set up on a stand next to the center camera.  I'm not kidding.)  I usually give them the file off my M10 afterwards, which they use for the final broadcast.  I'm wondering if I could just give them a direct line feed off of the FP24 instead.

[ts]

Energizer advanced or ultimate. Buy them at Sam's Club. Per Jon's response above, I have no idea how long they'll last with 48V on and your mics. I ran my Nak 1000's on 15V for close to 4 hours with plenty of power left. I also used to run my SD MP2 with lithiums for 4 hour shows with no problems. KM184's>SDMP2 set at 48V.

[voltronic]

Energizer advanced or ultimate. Buy them at Sam's Club. Per Jon's response above, I have no idea how long they'll last with 48V on and your mics. I ran my Nak 1000's on 15V for close to 4 hours with plenty of power left. I also used to run my SD MP2 with lithiums for 4 hour shows with no problems. KM184's>SDMP2 set at 48V.

Thanks I'll give those a try.  Probably going to wind up with something rechargeable though.  Just found an old set of Energizer 1850mAh rechargables that I'll try first, but I'll then look for something more like 2400mAh in the meantime.

To Jon's point - My CM3s draw 3.5mA which is the same as your KM184s so I'm cautiously optomistic. 

[ts]

Energizer advanced or ultimate. Buy them at Sam's Club. Per Jon's response above, I have no idea how long they'll last with 48V on and your mics. I ran my Nak 1000's on 15V for close to 4 hours with plenty of power left. I also used to run my SD MP2 with lithiums for 4 hour shows with no problems. KM184's>SDMP2 set at 48V.

Thanks I'll give those a try.  Probably going to wind up with something rechargeable though.  Just found an old set of Energizer 1850mAh rechargables that I'll try first, but I'll then look for something more like 2400mAh in the meantime.

To Jon's point - My CM3s draw 3.5mA which is the same as your KM184s so I'm cautiously optomistic.

Yes, if you intend on using it a lot, definitely go with another power solution. I don't use it that much so I find the Lithiums to be most convenient. Otherwise they're a huge waist.

[carlbeck]

I just picked up one of these as well, does anyone know how long I could expect to power AKG 414's at 48v phantom with rechargables?

[voltronic]

I'm getting my FP24 on Monday, and I'm planning to do a runtime test with the rechargeables I have before I go out and buy higher-capacity ones.  Going to set the M10 to record in mp3 format, turn on 48V, put the gain up halfway and let it record while I'm out at work or over night.  I'm expecting that when I load the file up in software I'll be able to see / hear when the power starts dying.

[DSatz]

I ran a test like this a few months ago, and am sorry now that I didn't write down the details. In my case the batteries lasted so long that it no longer mattered for any practical recording that I would make nowadays; IIRC it was well over 10 hours, maybe a bunch longer.

However, I mainly use Schoeps CMC 6-- microphones, which can run either on 12-Volt or 48-Volt phantom powering, and I don't remember which setting I used. (In practice I would use the 12-Volt approach because it uses only half as much power: 5 mA x 48 V = 240 mW while 10 mA x 12 V = 120 mW.) It's definitely important to connect a pair of the type of microphone that you intend to use, because the current drawn by the phantom circuit in the preamp depends greatly on that; just having the phantom powering turned on, with nothing drawing the current, won't test much.

Also, the LED brightness setting matters in this; those LEDs use a lot of current, and I wish they could be made even dimmer than the dimmest standard setting.

--best regards

[voltronic]

Just got my FP24 and tested it out.  Really nice unit, and I can't believe that a piece of gear that is 12+ years old still performs this well.  Other than paint wear and some minor crud in the small switches and LEDs, the only real flaw in mine is a slightly scratchy headphone pot in one area.  The mic gain pots are totally clean.  I think I'm going to just use it as is for now, and then I'll send it to SD for a tune-up in the off season.  I was a bit nervous about buying something this old, but I'm glad I did.  Thanks to everyone here for the advice, as always.

Regarding the LEDs - I agree with DSatz, they are VERY bright and I also think they could have gone much dimmer on the low setting.  The max setting reminded me of when my 7th grade science teacher burned magnesium!

Just started my runtime test with the 1850mAh Energizer rechargables I have.  CM3s (drawing 3.5mA each), 50% gain, low meter brightness, Tape out, no headphones.  I'll report back on how it did, but these batteries are really old so I'm not expecting anything miraculous.

[voltronic]

Recording started squealing like a stuck pig at about 3 hours 40 minutes and cut out shortly thereafter.  I was also playing around with it for at least a half hour beforehand, making a few short recordings even briefly at max gain and dazzling myself with the meter lights.  I'd say conservatively I got 4 hours out of these very old rechargable batteries.  That's plenty good enough for now, but I still will probably pick up some higher capacity ones.  WOW is this preamp quiet!

[tim in jersey]

The super-bright LEDs are actually quite handy when recording outdoors in full sun... Although I don't recommend  leaving them engaged full-time, sucks up a lot of juice.

[chinariderstl]

WOW is this preamp quiet!

It is super nice man.  When the funds are available, I'll probably trade in my Mixpre and move up to a new Mixpre-D.

Whoring it up. 

[Ultfris101]

WOW is this preamp quiet!

It is super nice man.  When the funds are available, I'll probably trade in my Mixpre and move up to a new Mixpre-D.

Whoring it up. 

The thing that keeps me from being all over the Mixpre-D is the power requirement. I can't run it off the 9v DVD batteries I already have.

I really like the USBPre2 but the form factor is leaving me a little uncomfortable in the bag. It's just made more for running on a desktop than in a more mobile scenario. The Mixpre/Mixpre-D is rugged with locking connectors, nothing on the "bottom" when you stand it up in a bag, etc.

I had a Mixpre for a while and it's great. Easy to power. I made a hirose battery cable of my own and I was all set. Kind of wish I still had it but had to choose between the Mixpre and USBpre2.

One thing about the FP24/Mixpre if it hasn't already been said, get yourself some mic pads or anything even moderately loud will push you in the red.

[Fried Chicken Boy]

I just picked up one of these as well, does anyone know how long I could expect to power AKG 414's at 48v phantom with rechargables?

Not an FP24 but I have a 2nd gen MixPre (non -D, Hirose external power input).  I actually did a runtime test using my 414s and rechargeables a few years back and, IIRC, barely got past the 2 hour mark when the "recording started squealing like a stuck pig" as voltronic put it.  414s draw a fair amount of juice so I'm not surprised I only got a few hours.  Ted made me a dual-input power cable so I can run the MixPre off DVD batteries and hot swap when necessary.  Runs forever now and I've yet to run into a situation where I had to hot swap the battery.  YMMV.

[carlbeck]

I just picked up one of these as well, does anyone know how long I could expect to power AKG 414's at 48v phantom with rechargables?

Not an FP24 but I have a 2nd gen MixPre (non -D, Hirose external power input).  I actually did a runtime test using my 414s and rechargeables a few years back and, IIRC, barely got past the 2 hour mark when the "recording started squealing like a stuck pig" as voltronic put it.  414s draw a fair amount of juice so I'm not surprised I only got a few hours.  Ted made me a dual-input power cable so I can run the MixPre off DVD batteries and hot swap when necessary.  Runs forever now and I've yet to run into a situation where I had to hot swap the battery.  YMMV.

I can't run anything else off my Naztech without a power distribution box so I bought some Panasonic eneloop 2550 mah batteries hoping to get three hours out of them? I'll do some run tests tomorrow but I know the 414's are hogs with the LEDs. Two hours would work as long as there is a set break but if I could get three hours I'd be really happy.

[voltronic]

They are selling these for cheap at my local grocery store - thinking I'll give them a shot given the thorough review here:
http://www.amazon.com/Duracell-Rechargeable-Batteries-Duralock-Technology/product-reviews/B00DSYFAEQ/ref=cm_cr_dp_text?ie=UTF8&showViewpoints=0&sortBy=byRankDescending#R5USCMSI5N7I7

[carlbeck]

I did a run test today with my new Panasonic eneloop AA batteries. Running the FP24 at 3/4 gain, led on low & 414's I got 5:41 before it died. I'm extremely pleased with that performance, more than I'll ever need for the typical show & without having to swap batteries or turning the preamp off in between set. For $30 on amazon with a smart charger I think the eneloops are a great deal.

[voltronic]

I did a run test today with my new Panasonic eneloop AA batteries. Running the FP24 at 3/4 gain, led on low & 414's I got 5:41 before it died. I'm extremely pleased with that performance, more than I'll ever need for the typical show & without having to swap batteries or turning the preamp off in between set. For $30 on amazon with a smart charger I think the eneloops are a great deal.

That's outstanding performance, especially considering the 414 draws 4.5 mA!  Are these regular Eneloop (white label) or the higher-capaciy Eneloop XX (black label)?  The tradeoff with the high-mAh XX is shorter life expectancy from what I understand.

[carlbeck]

They are the black eneloop pro's. Four AA batteries & charger for $30 on Amazon.
Btw, I don't know if my FP24 has had the battery spring replaced/repaired but the rechargeables worked fine without any trimming to the batteries or mods.

http://www.amazon.com/gp/product/B00JHKSL1O/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

[voltronic]

Mine needed the battery mod.  I think if you have a hirose power connector then you have the later revision which also has the different battery spring.  My power connector is the older barrel type.

[carlbeck]

Mine needed the battery mod.  I think if you have a hirose power connector then you have the later revision which also has the different battery spring.  My power connector is the older barrel type.

Mine is the old barrel type as well, no problems with the batteries.

[voltronic]

That's outstanding performance, especially considering the 414 draws 4.5 mA!  Are these regular Eneloop (white label) or the higher-capaciy Eneloop XX (black label)?  The tradeoff with the high-mAh XX is shorter life expectancy from what I understand.

2x NiMH AA @ 2.5Ah = 6Wh

2x 48V *4.5mA = 432mW, round up to 0.5W for conversion losses.

So about six hour runtime means the box was burning 1W, half was for phantom, half for the box.  Runtime with no phantom load should be about 12 hours.

Please pardon my ignorance and limited math skills - how do you determine the 2 AA's at 2.5Ah ea. come out to 6Wh?  The rest of it I understand.

[voltronic]

They are 1.2V nominal, so that's 2 * 1.2V * 2.5Ah = 6Wh

Got it - thanks.

[Jamos]

I can confirm that the black Eneloop XX batteries will have a shorter lifespan than regular Eneloops.
We've done extensive rechargeable battery tests, and have found that the regular eneloops offer some of the best value/$$$.  The XX's are great too, just know that you'll get far less cycles out of them before they refuse to recharge.

I still love my FP24 / MixPre for it's size, quality, powering, and features!

[voltronic]

I can confirm that the black Eneloop XX batteries will have a shorter lifespan than regular Eneloops.
We've done extensive rechargeable battery tests, and have found that the regular eneloops offer some of the best value/$$$.  The XX's are great too, just know that you'll get far less cycles out of them before they refuse to recharge.

I still love my FP24 / MixPre for it's size, quality, powering, and features!

Right, the XX are only rated for 500 cycles.  I could probably record 2 full concerts on one set though.  For now, I think I might stick with the old ones I have, as I've done a couple more runtime tests and get a solid 3:20-3:30 each time before they start to give out.

[carlbeck]

I can confirm that the black Eneloop XX batteries will have a shorter lifespan than regular Eneloops.
We've done extensive rechargeable battery tests, and have found that the regular eneloops offer some of the best value/$$$.  The XX's are great too, just know that you'll get far less cycles out of them before they refuse to recharge.

I still love my FP24 / MixPre for it's size, quality, powering, and features!

Agreed, they are "only" rated for 500 cycles. I was willing to trade that for higher capacity since the reality of me doing 500 shows with one set of batteries is highly unlikely. Maybe if I was allowed out of the house more 

[voltronic]

Since the next thing I'm recording is a long recital with a long sound check before, I picked up a set of the Duracells I mentioned before, which are supposedly re-branded Eneloop XX's.  Just finished a run test with same parameters, and I got to 5 hours 57 minutes before the squealing of low battery crept into the recording.  That sealed the deal for me on going with internal rechargeables, as did the price - only $13 for a 4-pack with charger at the local grocery store:
http://www.duracell.com/en-us/products/battery-chargers/duracell-ion-speed-1000-battery-charger