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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: F0CKER on April 26, 2010, 10:30:05 AM
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Anyone else running this combo?
I just got my 248 back from Oade and was testing the setup for the firt time at home over the weekend and I had trouble getting a strong signal on the 661. I'm running Milab VM44 mics-> 248-> 661 going line level in on the 661. I had the gain on the 661 and the 248 both cranked to the top and I was barely getting a signal peaking at -12dB. I had the stereo cranked pretty loud and the mics up close to the source. I've never had that much trouble getting a strong signal when I was testing other gear in a similar fashion. I'm going to field test everything Wed, so hopefully I'll have a better indication in real world settings with higher SPL. I still get the sense I'm not getting enough gain with this setup.
Has anyone experienced anything similar?
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i'm having simmilar issues with my new Littlebox > Sony PCM-M10 (Mics are Audio Technica 4041's) rig
i've only run 1 show, but i was peaking ~-25dB.
Littlebox was cranked & M10 (line-in) was @ 10
after normalizing in post the show sounds fine,
just wondering if this is normal as i'm new to the 24bit world...
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^^^ I'm not a user of 4041s but that does not sound normal at all. I get very strong levels on my littlebox>M10 using DPA 4021s, which aren't particularly "hot" mics. I leave the littlebox knobs usually around 12 o'clock (i.e., halfway up) and M10 at 4 or 5; that usually gets me levels peaking in the -3dB range at a rock show.
What kind of music were you recording? Does your littlebox have variable power? Although, mine does, and I still get good levels only using 24V with it.
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Here are the VM44 specs as well.
Product name Milab VM-44 Classic
Type Condenser
Max. SPL (1% THD at 1 kHz) 128 dB*
Max. SPL with 12 dB pad 140 dB*
Sensitivity at 1 kHz 15 mV/Pa (± 1dB)*
A-weighted noise level (IEC 179-A) 21 dB*
Power supply 12-52 V Phantom (DIN/IEC)
Current consumption 4 mA
Output impedance <200 Ω
Minimum load impedance 1 kΩ
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Sensitivity at 1 kHz 15 mV/Pa (± 1dB)*
Ok, so standard or slightly above (neumann and schoeps are around this output).
No pad engaged on the 661 or the mics?
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No pad, no attenuation....nothing.
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Focker, I'll venture a guess (and it's just a guess) that your living room stereo is not nearly as loud as you think it is compared to a rock show. I've done that before thinking it was a decent representation, and maybe it is for a coffeehouse acoustic type setup, but think about a Gov't Mule show (for instance) where you can't hear your buddy talking next to you, and you walk out with your ears ringing. Is your stereo that loud? Probably not. I figure it's about 20db louder than I would ever run my home stereo, and that's quite a bit.
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Focker, I'm really sorry to tell you that I can confirm that I had the same results. I never really solved the issue for the limited time that I had the 661 which I sold precisely because it didn't match well either my m118 or m248. Both of the Oade preamps have unbalanced outputs, so you only have one option, which is to use the 'Line In' on the 661...but as you experienced I couldn't get a reasonable gain level on the 661 using either of my preamps. You also can't use the XLRs on the 661 either because the 661's XLRs expect a balanced signal.
Anyway, I attributed the low levels to the low gain structure of the 248, combined with the low gain range on the Line In of the 661. The 661 Line In just doesn't provide much gain range.
On the 248 side of the equation, even though the 248 has adjustable gain, I don't think there is a whole lot of gain range being controlled by those knobs, so I think the output gain on the 248 must only go up to something marginally above...say...the fixed 20db of the m118/m148. I don't know what it gets up to, but I'd be shocked if someone said that the 248 provides anything more than about 20 to 25db of gain.
Actually, you said you had the stereo cranked. Hate to say it, but if you're able to get up to -12db during the show, I would personally consider that a success because I wasn't getting anywhere near -12db.
FWIW, after selling the 661, I bought a Sony D50...that combo kicks ass and sounds fantastic together and the Line In gain range on the D50 combines perfectly well with the 248. I also got great results when I combined the 248 with an R-09HR. So, FWIW, the gain range on both the D50 and R09HR are alot better when combined with the 248...and I understand the both have nice, low noise gain stages.
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Thansk for the replies, what about some form of line level matching between the RCA out of the 248 and the XLR in of the 661?
Would something like this work?
http://www.bhphotovideo.com/c/product/203683-REG/Rane_BB_22_BALANCE_BUDDY_2_Channel.html#specifications
Or an adapter of some sort?
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^ Nice!
I can't answer the question for sure, but sure seems like that's getting to the source of the problems that I was experiencing. If I'd known about this at the time I was experiencing the problems, I'm sure I'd have given it a try such that I could answer your question now! ;) Good luck!
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Focker, you might want to send DATBRAD a PM. He did a TON of investigation into the 661 design and he understands the differences between consumer and pro gain stages...where I can honestly say I don't. In fact, when he bought the 661, he commented that one of the great design features of the 661 was the pro gain stage. Anyway, I bet he could help you answer the questions you have about whether or not that RANA box would solve your problem.
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Focker, Like we talked about a while back, the output of your 248 is set to unbalanced -10db consumer level, and the XLR input of the 661 is set for balanced +4db pro line level signals. That is a 14db difference, which is a pretty large swing.
I actually picked the 661 for that reason, because my AKG460>Sound Devices MP-1 combo outputs a line level so hot, that recorders I tried with unbalanced -10db consumer level RCA line inputs were often overloaded. The purpose of the 248 is to add gain and provide phantom, but if you are not getting enough gain that way, you might be better off just going straight into the 661 mic in.
I have one suggestion for you to try at home. Switch the XLR input to mic in, no phantom, and go into the 661 menu and put the attenuator on the max, -18db, and see if you can get good levels with the 661 gain knob set at about 6-7 with your stereo cranked.
Later....
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Focker, Like we talked about a while back, the output of your 248 is set to unbalanced -10db consumer level, and the XLR input of the 661 is set for balanced +4db pro line level signals. That is a 14db difference, which is a pretty large swing.
I actually picked the 661 for that reason, because my AKG460>Sound Devices MP-1 combo outputs a line level so hot, that recorders I tried with unbalanced -10db consumer level RCA line inputs were often overloaded. The purpose of the 248 is to add gain and provide phantom, but if you are not getting enough gain that way, you might be better off just going straight into the 661 mic in.
I have one suggestion for you to try at home. Switch the XLR input to mic in, no phantom, and go into the 661 menu and put the attenuator on the max, -18db, and see if you can get good levels with the 661 gain knob set at about 6-7 with your stereo cranked.
Later....
I've had my best results with the 248, while using Schoeps, keeping the gain at a minimum and using my 722 to bring up the levels. I never had a problem.
I did try going mic in, no phantom with the attenuation set to -18dB and got plenty of gain but there was way too much noise on the recording. Definitely not an option.
I'm torn here, I really do like the sound of the vm44->248. I think I either need to test out another deck or try something else to bring up the unbalanced signal to match the pro level.
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Focker, Like we talked about a while back, the output of your 248 is set to unbalanced -10db consumer level, and the XLR input of the 661 is set for balanced +4db pro line level signals. That is a 14db difference, which is a pretty large swing.
you need an impedance converter
I found a couple of items at Markertek- which I have had good dealings with in the past- I swear I though I saw a tec-nec cable they maybe that would step up the impedance- but I could be remembering a dream... :)
any how not cheap but all good manufactures:
http://www.markertek.com/Audio-Equipment/Audio-Interface/Impedance-Matching-Transformer/Ocean-Matrix/OMX-OTLMAX.xhtml?OMX-OTLMAX (http://www.markertek.com/Audio-Equipment/Audio-Interface/Impedance-Matching-Transformer/Ocean-Matrix/OMX-OTLMAX.xhtml?OMX-OTLMAX)
looks promising:
http://www.markertek.com/Audio-Equipment/Audio-Mixers-Accessories/Microphone-and-Line-Mixers/Radial-Engineering/J+4.xhtml?RAD-J4 (http://www.markertek.com/Audio-Equipment/Audio-Mixers-Accessories/Microphone-and-Line-Mixers/Radial-Engineering/J+4.xhtml?RAD-J4)
Both Ocean Matrix ( who specializes in Video products) and Radial are both well made.
ahhh !!! the Tec nec model:
see the OTL-2S Low to High:
http://www.markertek.com/Audio-Equipment/Audio-Interface/Impedance-Matching-Transformer/TecNec-Cables-Connectors/OTL-1S.xhtml?OTL-2S&bs (http://www.markertek.com/Audio-Equipment/Audio-Interface/Impedance-Matching-Transformer/TecNec-Cables-Connectors/OTL-1S.xhtml?OTL-2S&bs)
I think this may not go the way you need it to: looks like it is more of just an isolator
http://www.markertek.com/Audio-Equipment/Audio-Interface/Impedance-Matching-Transformer/Applied-Research-Technology/DTI.xhtml (http://www.markertek.com/Audio-Equipment/Audio-Interface/Impedance-Matching-Transformer/Applied-Research-Technology/DTI.xhtml)
good luck
--Ian
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Thanks for those links Ian. I may look into it further, but I'm more inclined to find a deck to match the 248 than to add more boxes in the line. I'm going to test a HDP2 on loan from another TS.com member and see if it works any better - also giving me a chance to test the 44-> 248 sound out if it does. If it works and I like the sound, then I'll make a switch. If I don't like the 248 sound with the 44's, then I'll keep the 661 and consider a different preamp.
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Thanks for those links Ian. I may look into it further, but I'm more inclined to find a deck to match the 248 than to add more boxes in the line. I'm going to test a HDP2 on loan from another TS.com member and see if it works any better - also giving me a chance to test the 44-> 248 sound out if it does. If it works and I like the sound, then I'll make a switch. If I don't like the 248 sound with the 44's, then I'll keep the 661 and consider a different preamp.
I'm gonna bet that the 248 will kick butt with the VM44's. When I first got my m248, I was OK with the sound, but the more I've used it the more I've come to respect and enjoy this preamp. I only wish that it had an external powering option, although I've given more than a couple of thoughts to putting a hole in the side of the box and jumpering in a battery connector.
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I'm inclined to think the two will match really well. From what I've heard of the 44's, and through my limited use of them, I think it's a perfect match. The 248 is definitely a unique sound, IMO.
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I think these impedance transformers are probably the same thing that's in those boxes, and they don't take up as much room. I have the Radshack ones and use them to run unbalanced > balanced > R4 quite a bit.
http://www.radioshack.com/product/index.jsp?productId=2062444&filterName=Cable+type&filterValue=Audio+adapters
http://www.hosatech.com/product/340100/MIT-129/_/Impedance_Transformer%2C_14_in_TS_to_XLR3M
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I think these impedance transformers are probably the same thing that's in those boxes, and they don't take up as much room. I have the Radshack ones and use them to run unbalanced > balanced > R4 quite a bit.
http://www.radioshack.com/product/index.jsp?productId=2062444&filterName=Cable+type&filterValue=Audio+adapters
http://www.hosatech.com/product/340100/MIT-129/_/Impedance_Transformer%2C_14_in_TS_to_XLR3M
I'm probably the wrong guy to respond cause I haven't used any of these products (other than being familiar with Focker's root problem), but my concern with these things is that, yes they might solve the balanced/unbalanced problem to eliminate XLR hum, but they wouldn't address the issue related to the pro/consumer -14db gain difference.
OTOH, Focker, if you're able to use the XLRs with the switch in either the 'mic-in' or 'line-in' position without humming, perhaps you'd no longer need to worry about using the separate 1/8 inch line in jack.
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I only wish that it had an external powering option, although I've given more than a couple of thoughts to putting a hole in the side of the box and jumpering in a battery connector.
One exists here in Dallas. It was modified here locally as well. Next time I see the owner i'll ask to pry into the 248 and see what was done.
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That's something I'd be interested in as well.
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The 248 has a single 12V battery inside...two wires connecting the battery to the rest of the preamp.
I'm no electrician (caveat emptor), but pretty sure all you need to do is wire up a connector with a 'parallel' wiring configuration (as opposed to 'series'...electricity 101) and then hook up an external battery that supplies 12V with a connector that has the same polarity as the internal battery.
My thoughts were to either drill a hole in the side of the 248 box and run the wires outside of the box to the connector, or just find a spare location on the exterior of the 248 box to mount the connector onto and wire it up on the inside. The external battery of course would have a connector that mates up to this connector. You'd also need a battery charger...the charger would be wired up with the same connector as 248 (not the battery).
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Sound like you need to sell me the 661 and grab a new deck!! >:D JK
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I think these impedance transformers are probably the same thing that's in those boxes, and they don't take up as much room. I have the Radshack ones and use them to run unbalanced > balanced > R4 quite a bit.
http://www.radioshack.com/product/index.jsp?productId=2062444&filterName=Cable+type&filterValue=Audio+adapters
http://www.hosatech.com/product/340100/MIT-129/_/Impedance_Transformer%2C_14_in_TS_to_XLR3M
I'm probably the wrong guy to respond cause I haven't used any of these products (other than being familiar with Focker's root problem), but my concern with these things is that, yes they might solve the balanced/unbalanced problem to eliminate XLR hum, but they wouldn't address the issue related to the pro/consumer -14db gain difference.
OTOH, Focker, if you're able to use the XLRs with the switch in either the 'mic-in' or 'line-in' position without humming, perhaps you'd no longer need to worry about using the separate 1/8 inch line in jack.
Well, I assumed he would then go in the XLR "mic in" jacks on the 661, which would resolve the gain issue.
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I think these impedance transformers are probably the same thing that's in those boxes, and they don't take up as much room. I have the Radshack ones and use them to run unbalanced > balanced > R4 quite a bit.
http://www.radioshack.com/product/index.jsp?productId=2062444&filterName=Cable+type&filterValue=Audio+adapters
http://www.hosatech.com/product/340100/MIT-129/_/Impedance_Transformer%2C_14_in_TS_to_XLR3M
I'm probably the wrong guy to respond cause I haven't used any of these products (other than being familiar with Focker's root problem), but my concern with these things is that, yes they might solve the balanced/unbalanced problem to eliminate XLR hum, but they wouldn't address the issue related to the pro/consumer -14db gain difference.
OTOH, Focker, if you're able to use the XLRs with the switch in either the 'mic-in' or 'line-in' position without humming, perhaps you'd no longer need to worry about using the separate 1/8 inch line in jack.
Well, I assumed he would then go in the XLR "mic in" jacks on the 661, which would resolve the gain issue.
:coolguy:
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Finally had a chance to run the Miabs and the 248. Worth the wait, this is the combo I've been searching for quite some time. I love the way the Milabs match with the 248, very natural fitting much like the schoeps match with the 248 so well. If anyone's interested, here's the recording from the Heavy Pets Thursday night as a reference. http://bt.etree.org/details.php?id=535312&edited=1. Obviously only one show with them, I'll need to tape in some different rooms, but I really like what I hear with this combo so far.
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F0CKER Glad you like the VM 44's with the M248 - yes run the combo some more and share your results!
super cool
--Ian