High-end inline attenuator pads - recommendations?

[666666]

I made a similar post recently at another section of gearslutz, but I wasn't getting the answers I was looking for. I know the "remote" crew here can appreciate true high-fidelity, this is what I'm after, I should have posted here first.

I'm looking for some inline attenuator pads to pad the mic output into the mic pre, or pad the pre output into the recorder. -30db / -35db would be perfect. BUT, I'm very concerned about any harm that a typical, readily available sound reinforcement grade inline pad may cause to the quality of the path.

This may not be a common concern in the remote world, but I will be close miking some very loud instruments / sounds and some of my pres just don't have a low enough gain settings to accomodate... and no pads.

I have searched around and have not yet found an inline pad product specifically marketed for "high-end" recording. The only thing I've come across that is likely "safe" to use is the Schoeps MDZ 10 and MDZ 20 inline attenuators... haven't tested them, but I can't imagine Schoeps would offer anything less than top-quality products.

Schoeps Inline Attenuators

Problem with the Schoeps, they only offer -10db and -20db and I could use -30db or -35db. I suppose I could stack two Schoeps pads to achieve -30db, but I'm sure that doing so would not be a good idea in the name of trying to keep the path as pure as possible. Plus this would be quite costly just to achieve a fixed -30db.

Aside from trying to build my own custom pads, anyone have any suggestions for good "high-end" inline attenuators?

I'll admit, I do not know for a fact that a typical Shure or AT switchable inline attenuator pad will "harm" fidelity, I have yet to test this and am not able to test right now. But I am preparing for an important recording project coming up soon and just wish to be fully prepared beforehand. I do not want to rely on "common grade" parts, only to discover they are inadequate during a session, then need to wait a week to get something better. Other Shure products I've used / tested in the past (for instance) have proven to be just fine for sound-reinforcement but not adequate for ultra high-end critical recording.

I did consider building my own pads in the past, but I just don't have the time now. Would like to avoid if possible. I guess if Schoeps offered a -30db pad I'd be set. I briefly checked DPA, it appears they do not offer inline pads. Are there any other high-end mic or pre manufacturers offering inline pads perhaps? I've looked briefly, have not found anything.

Any ideas welcome.

Thanks

[tsvisser]

I have some of the Schoeps pads and can't necessarily say for certain that they are of better discernable quality than other cheaper pads. An attenutor is a relatively simply circuit, so perhaps one area where using better materials may not necessarily translate to better performance. I'd recommend getting the Neutrik "male to female XLR adapter" and loading it with the high quality parts of your choice.

[tourtelot]

DIY with some high quality resistors will be as good as it gets. The Schoeps pads use some sort of off-the-shelf resistors as far as I know. Nothing too tricky in a pad. Check Uneeda Audio site for values.

D.

[hazelmossobrien]

True systems makes the only TRS inline PAD i've seen. Pretty cool for attenuating between your preamp outputs and your ADC.

True also makes an 8 channel DB25 attenuator for cheap.

TRUE Systems

[madtheory]

For audio, it would be pretty hard to find a resistor that does anything other than attenuate the level. No distortion or noise of any kind. Maybe you should do a nightcourse in electronics? Might save you some money in the long run, and be fun. It's good to be armed with some knowledge, what with all the snake oil out there.

[bishopthomas]

Originally Posted by madtheory

For audio, it would be pretty hard to find a resistor that does anything other than attenuate the level. No distortion or noise of any kind. Maybe you should do a nightcourse in electronics? Might save you some money in the long run, and be fun. It's good to be armed with some knowledge, what with all the snake oil out there.

That's exactly what I wanted to say, but in much nicer terms. It irritates me so much when people get so involved in such trivial details. This might be the most ridiculous thing, even past the "cables made of God's toe hair" theorists. There are so many other variables to worry about than what kind of packaging is used to house a resistor...

[666666]

Thanks for the replies so far.

When shooting for premium fidelity, every single element in the signal path is critical. If I am about to add a new element to my path, I do not consider this a trivial issue, but a very important one.

But, true, I am not a tech, and for all I know ever resistor ever made, cheap or expensive, will offer the EXACT same audio performance. But I certainly will not assume anything.

I've also read something about when making attenuation pads, depending on how it's wired up, the resistors need to be "matched". Assuming this is true, I then I have to wonder to myself, when you buy a Hosa inline attenuator pad at Guitar Center that was likely mass produced in China, did they match the resistors? I'd be very suspect about ANY relatively inexpensive mass produced attenuator pad, I'd doubt that any attention was paid to making certain they offer absolutely premium fidelity. Most people will be using them in non-critical situations anyway, that's really what they are designed for... typically.

But once again, I am indeed NOT a tech, that's why I'm asking about this. Short of getting my hands on every inline attenuator / resistors ever made and doing my own shootout tests using my EARS as the judge, I really have no way of knowing what to expect.

I suppose that if I wish to guarantee premium quality, I'll need to wire up pads myself as some have suggested here, making sure that everything is done "correctly". I'm not a tech but I can solder well and I can follow instructions. I was hoping to avoid this though being that I just don't have much free time these days for extra "projects".

I will investigate all options mentioned. I appreciate the help.

[tsvisser]

There are some variations between resistors, so it's not fair to classify them all as exactly equal. A 1/4w metal film resistor could sound different than a 20w wirewound resistor, typically used in power circuit. I think that once you are using the appropriate composition and spec of resistor for the application, they are very very close to a level playing field. Matching is another issue. Hosa likely orders resistors in batches of thousands and may not even test values, probably just pull them from the tape reel and use them. I doubt most manufacturers bother matching resistors for something like an inline pad. When ordering resistor from the manufacturer or distributor, you can get different tolerances, which is supposed to guarantee that the value of the resistor will fall into a certain range of values, usually a smaller range for more premium offerings. For 1/4 watt through hole resistors from Digikey, tolerances vary from +/- 0.01% to +/- 5%. The +/- 5% resistor may not offer better noise performance than the +/-0.01% resistor, but you can rely on the tighter tolerance resistor to be better matched to each other if using them in stereo sets.

[7rojo7]

Sounds to me like you'll need a pad between the capsule and the amp in the mic, if you're recording loud sources
Most switchable capsule SDC offer some kind of pad module to put behind the capsule.
Then a mic pad if you need more. Stop distortion where it starts. Shure pads work just fine, if you want better, you'll probably have to make your own. 3 resistors H-pad, you can make one inside an XLR connector, put it on the male end.

[madtheory]

Hi 666666. As tsvisser has said, resistors can be manufactured to very tight tolerances, and they are all very cheap. An inline pad is one thing that is very easy to do with 100% accuracy. These days, even resistors rated at 1% tolerance actually measure with greater toelerance much of the time, for a given batch.

I think you're a person who's hungry for knowledge, and I seriously think you'd benefit greatly from a course in electronics! Honestly, it's fun.

Otherwise, get in touch with John at naiant.com he makes inline pads and is extremely helpful with info on his circuits.

7rojo7 you are correct in theory, but in practice a pad after the mic does the trick 99% of the time.

[Thomas W. Bethe]

Markertek sells a good pad Rapco Patchadap In-Line Attenuators Attenuation Devices at Markertek.com also PROCO makes a good pad Pro Co MAX-10 10db Microphone Attenuator (Pad)

Or you can make your own Uneeda Audio - Build your own attenuator pads and you can order resistors from DigiKey and do your own matching,

I think a capsule attenuator is really what you need.

Please note that you cannot phantom power a microphone through a pad so you will need an external phantom power supply before the pad.

[NoKi]

Hi,

may I ask why you are using a preamp at all, if you need a pad of 30 dB and amplify it maybe 30 dB afterwards again? Would not a P48 power supply all you need to feed a line input device? You will not add any distortions/noise by the reamplification and no losses in symmetry due to the pad resistors.
I did this sometimes and it works.

Nils

[madtheory]

COnnecting a mic directly to a line in is not good practice, the impedance could be an issue, you break the 1:10 rule. Noise floor and frequency response might be put well out of spec. but of course that depends on the mic and the input device used.

[NoKi]

Originally Posted by madtheory

COnnecting a mic directly to a line in is not good practice, the impedance could be an issue, you break the 1:10 rule. Noise floor and frequency response might be put well out of spec. but of course that depends on the mic and the input device used.

No, a mic has a much lower output impedance (< 100 Ohm) than most line devices and most mic preams have much lower input impedances (1 kOhm) than line inputs (> 10 kOhms). The noisefloor or freq. response is not affected in a negative way.

Nils

[Remoteness]

There's cool pad calculator in The Beginner's Guide -- Check out post number 14.

We build our own pads; matter of fact they are mounted into our patch bays just above the stage outputs/preamp inputs.
My buddy designed printed circuit boards that fit perfectly behind a 1U rack bay... We stuffed our own resistors; we have multiples of -30 dB; -20dB and -10 dB pads.

We also use inline XLR barrels when applicable.

[huub]

Steve, I wonder; I suppose your recording equipment can handle +24 dBu right? I have never come across mics or devices that put out more than +24, when do you need your pads? I guess vintage mic amps cannot handle very high levels?

Huub

[madtheory]

Originally Posted by NoKi

No, a mic has a much lower output impedance (< 100 Ohm) than most line devices and most mic preams have much lower input impedances (1 kOhm) than line inputs (> 10 kOhms). The noisefloor or freq. response is not affected in a negative way.

Nils

OK, but the nominal output impedance for condensers ranges from 50 to 200, dynamics can be up to 600 ohm. There is a similar range of variation with mic pre in and out impedance. So doesn't it depend on what is being used? Try it next time you mike a kit. The dynamics will have generate enough voltage to drive a line input, but it will most likely be dull and noisy. That is my experience anyway, with various systems.

[Corran]

I can understand not wanting a cheap attenuator that might be junk quality and parts from Hosa or something.

But the Shure should be fine.

Personally I use a few from Naiant, available here: Naiant Studio Store - Microphones . They are handmade by him and I can tell you I've never noticed a bit of difference when using them. You can get an assortment of 12 and 24 db ones and be set for whatever. And they are not expensive either.

[NoKi]

Originally Posted by madtheory

OK, but the nominal output impedance for condensers ranges from 50 to 200, dynamics can be up to 600 ohm. There is a similar range of variation with mic pre in and out impedance. So doesn't it depend on what is being used? Try it next time you mike a kit. The dynamics will have generate enough voltage to drive a line input, but it will most likely be dull and noisy.

I got your point; I focused more on high output condensers. But if you look into the specs of your gear you will not find a line input impedance to be lower than that of a mic input. The only difference is that a mic pre has a way lower equivalent input noise (due to their amplification). So, plugging a mic to line input of course only makes sense at extreme high levels, so that the input still has enough s/n ratio (e.g., a 20 mv/Pa condenser at 124 dB SPL has only about 0,6 V, and a 2 mV/ Pa dynamic 0,06 V!).

Nils

[rumleymusic]

They are very cheap and easy to make: I have a couple I made using the XLR Male to female extender from Neutrik and 3 vishay-dale 1/4w 1% metal film resistors. 2x681ohm and 1x150ohm if I remember. (for a 20dB pad) The 150 connects both the 2 and 3 pins and the 681's connect 2 and 3 individually. I use them to protect my interface inputs from a very hot line stereo signal I get at one location.

That Uneeda link is a good resource.

[Syngriner]

I can understand not wanting a cheap attenuator that might be junk quality and parts from Hosa or something.

But the Shure should be fine.

Personally I use a few from Naiant, available here: Naiant Studio Store - Microphones . They are handmade by him and I can tell you I've never noticed a bit of difference when using them. You can get an assortment of 12 and 24 db ones and be set for whatever. And they are not expensive either.

+1 on the Naiant pads. I have two each of the 12, 18 & 24db mic level pads and the 40db line to mic level pads. They are inexpensive but not cheaply made and they work very well with no signal degradation.

[Remoteness]

Originally Posted by huub

Steve, I wonder; I suppose your recording equipment can handle +24 dBu right? I have never come across mics or devices that put out more than +24, when do you need your pads? I guess vintage mic amps cannot handle very high levels?

Huub

High out mics like the M149 and the TLM103 can be a bit much input, especially when the drummer is hitting hard...

Wireless mics can be a problem when they're set for talk and a singer is doing what they suppose to do; Sometimes you don't have time to recalibrate the mics and such. They can be set to line level or very close to that.

PT or any other playback device can also be a problem with too much output gain.

I just want the safety net.
Better to have the pads and no need them than to need the pads and not have them (ready to go.)

Having them in the bay is such a no-brainer for us.
No barrels to grab; no barrels to walk away on their own.
Everything is in the CRM right next to you or your associate.
Believe it or not, I don't design (or build) a bay without them.
We even have phase reverse patches for when you need to phase reverse a line input or output, but I digress.

[mixedupsteve]

Originally Posted by Thomas W. Bethe

Please note that you cannot phantom power a microphone through a pad so you will need an external phantom power supply before the pad.

This isn't always the case. A high current mic may have problems but many mics will be fine with a pad inline.

[Remoteness]

Originally Posted by mixedupsteve

This isn't always the case. A high current mic may have problems but many mics will be fine with a pad inline.

I never had a problem powering any mic through a pad.
What am I doing wrong?

[mixedupsteve]

Originally Posted by Remoteness

I never had a problem powering any mic through a pad.
What am I doing wrong?

I haven't either.

[Thomas W. Bethe]

Depends on a lot of things. The Phantom powering specs say it "Phantom power shall provide 48 volts DC to pins 2 and 3 through two 6.8 K ohm resistors. See here for more information Phantom Power Explained. If you are going into a balanced pad (H-Pad) you have resistance that the phantom power supply has not been designed for so you may not be getting the full 48 volts DC at the microphone. If it is like most microphones the power supply is quoted as so much voltage at so many ma's. Usually dropping the voltage is OK unless the microphone is designed for ONLY 48 volts DC and even then there is normally a line drop from the power supply to the microphone due to cable losses so you should be OK unless the microphone has a higher than normal current draw. If you are using a T-Pad or an L-Pad in the microphone attenuator then you are going to have bigger problems since the circuitry is unbalancing a phantom power supply that is suppose to be balanced with in 1% or less. If you want the ultimate then put the phantom power supply BEFORE the pad for full voltage and full current.

FWIW and YMMV

[Remoteness]

I can dig it.

Can you give us an example of which mic or mics cannot work with these pads?

[Corran]

Interesting. I used a couple of Naiant's pads with a pair of Earthworks QTC-1's on drum overheads and didn't experience a problem. They need a full 48v phantom power with 10mA of current.

[Jimbo]

Originally Posted by Syngriner

+1 on the Naiant pads. I have two each of the 12, 18 & 24db mic level pads and the 40db line to mic level pads. They are inexpensive but not cheaply made and they work very well with no signal degradation.

I'll +2 the Naiant pads. There's really no reason to spend more for something so simple.

[Chunky But Funky]

I was going to be picking up a Little Labs Redcloud for just this very purpose next week. I'm using DB25 disconnects on my rig anyway, and it gives you 31 stepped detents with gradually increasing attenuation.

The attenuation in dB is as follows, they follow the 31detents on the
pot :

1. 0
2. 0
3. .05
4. .25
5. 1.25
6. 2
7. 3
8. 4.5
9. 6
10. 8
11. 10.25
12. 13
13. 14
14. 14.75
15. 15.75
16. 16.5
17. 17.5
18. 18.25
19. 19.5
20. 21
21. 23
22. 25
23. 27
24. 28.25
25. 30.25
26. 32.25
27. 35.25
28. 39.25
29. 48
30. 87
31.90

I can't see that not covering about any situation! I'll be patching it between API pre's and convertors. Try pricing that out for 8 channels with individual barrels!

Doug