#41

I bought a used ROLLS mini mic pre which seems to work really well. Itā€™s not battery powered but provides full phantom.

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#42

Interesting.

How is it in terms of noise?

#43

Hard to say. I havenā€™t used it to record very quiet sounds or used any mics that require a ton of gain. But I havenā€™t had any noise issues so far.

#44

Did you get anywhere with this in the end?

I was also looking at something like this:

Itā€™s a shame there doesnā€™t appear to be much between DIY/supercheap(/crappy) and the Sound Devices MP-1, which is crazy expensive, and pretty big for a mobile preamp.

#45

I spent an afternoon at the LOM Audio space a few months back and got into a conversation with JonĆ”Å” about the That 1512/1510 Preamp circuits, which he described as a pretty solid option (likely better than most ce field recorder preamps).

thereā€™s some kits of that circuit floating around, although I havenā€™t found one yet that can run off USB or battery power. might be an interesting place to start thoughā€¦

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#46

Ah cool. I hadnā€™t come across the 1512/1510 before. A quick googling led me to some schematics and such, but indeed, didnā€™t see anything for USB or battery power.

I guess thatā€™s the bottleneck here, as there are plenty of DIY preamps out there, just not in this formfactor/featureset.

#47

not really. I think it all might have been fantasyland bullshit, ie, lots of things connected up on a circuit board that would probably be unusably noisy. analog electronics is not my strong point, and I was possibly just doodling on holiday for doodlingā€™s sake.

#48

Its been mentioned a few times before, but the Zoom H5/H6 really pairs nicely. I use my H5 as a portable 4 channel mixer with preamps. My only regret is I kinda wish Iā€™d gotten the H6 for the additional channels. H5 was $200ish used, I think.

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#49

Has anyone ever come across a Shure FP23? It looks identical (literally) to the Sound Devices MP-1, and although itā€™s discontinued might be an alternative as well.

edit:
I bit the bullet and ordered a used one off eBay and will report back.

On a side note, does anyone have any experience with rechargeable batteries in things like these? Do they hold up/work out well? Any specific brands? I remember my Zoom flying through rechargeable batteries like a decade ago, but I figure batteries have gotten better since then.

#50

Another potential candidate in this space graced my inbox today: https://centrance.com/store/MicPort-Pro-2-Mobile-Recording-Interface-p129318859

Their products are somewhat unique given the built in battery power.

I canā€™t vouch for quality or their ability to deliver but I figured others might be interested (I backed a successful kickstarter of theirs for a mobile battery powered pre which the company ultimately failed to bring to market)

#51

I stumbled on this. Anyone had any experience with it? Iā€™ve not used piezo and contact mics before but I believe you can attach them to acoustic instruments and, with some good placement and attention, get a decent sound. This looks like a cheap and mobile solution. Would love to hear peopleā€™s thoughts
http://pulplogic.com/product/ctact-box/

#52

Ask @pulplogic :slight_smile:

#53

Iā€™m sure you are looking for a less biased opinion, but Iā€™ll give you my take. The CTACT box is a pretty good contact mic pre-amp given the the self imposed constraints for size and power consumption. I wanted something small enough to connect to the side of my field recorder when using a contact mic on the go.

CTACT
CTACT.jpg2000Ɨ1330 1.23 MB

The CTACT box runs from a CR-2032 coin cell so the headroom is limited and the current needed to be kept low for a long battery life. It uses a OPA2314 which has pretty great specs for a low power rail to rail op amp. AC coupling is done through film capacitors and the pot is an Alps RK09L. Here is the schematic in case someone wants to do something similar DIY.
CTACT Box sch.pdf (26.0 KB)

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#54

Thanks @pulplogic. This helpful. Do you think it would work at the front end of Norns for use on a marimba or glock etc?

#55

Sure, I think it will.

#56

Hello everyone!

This is my first post here and I must confess that Iā€™m not really shure on whatā€™s this forum for exactly!(could anyone help me out? What lines?). However it looks nice (is it discourse running below itā€™s surface?).
I therefor hope that my question is at the right place (and in the right sub-space).

Iā€™ll get a Sound Decies MM1 for a recording next week. Due to some reason we canā€™t use wireless (nor long cable runs), so I have to set up 3 remote spots with independent recording devices and sync later.

For the Sound Devices MM1 Iā€™ll use my Sony PCM M10 recorder which has a 3.5mm line input.

The MM1 outputs via XLR, so Iā€™m gonna solder an XLR to 3.5mm stereo plug cable.
However, two questions arise Iā€™m not sure about and that I ask you to help clarify:

a) Would I need a padded line between the MM1 and the Sony? If I use my old Sound Devices MixPre I can barely use the normal output to feed the Sony because the signal is too hot (+22dDu max, +18dBu with engaged limiter). There is however a dedicated ā€œtape outā€ which outputs a consumer-friendly line level (+8 dBu, 2.0 V RMS) and compliments the Sonyā€™s input.
The MM1 is just equipped with a professional-line-level output (again +22/+17). Iā€™m not super tech-savvy but I foresee some trouble here: If the signal needs to be padded, would you tell me which resistor value to use?

b) On soldering the XLR to 3.5mm cable. The MM1 manual says: ā€œBoth the microphone input and line output of the MM-1 can be balanced or unbalanced without problems. When unbalancing (either input or output) ground pin 3 to pin 1. There is no change in gain with an unbalanced connection into or out of the MM-1.ā€

This corresponds to the rane tech note on sound system interconnection. Itā€™s a bit vague in the statement:

ā€œCROSS-COUPLED OUTPUT ONLY: CONNECT PIN 1 TO PIN 3 AT THIS END AND SET GROUND LIFT SWITCH TO ā€˜GROUNDEDā€™ (IF PRESENT).ā€

As the MM1 is transformer balanced, this just means bridging pin 1 & 3 and thatā€™s it? So cross-coupled only refers to the ground lift right?

Thank you.
Chris

#57

https://www.jlmaudio.com/shop/talkback-compressor-kit.html?display_tax_prices=1

SSL talkback compressor or a very fine THAT1510 mic pre - but not both at once :slight_smile: - this dudes so good/ its like a candy store

And those with valuable currency this stuff must be the best value for quality around ATM

#58

Could someone help me out with something? Whats the difference between a pre-amp and a pre-amp guitar pedal like the JHS Clover?

#59

They both boost signal. A pre-amp guitar pedal makes a signal hotter and/or more colored (eg Echoplex preamp) going into amplifier or DI. Guitar pedal preamps these days sometimes contain eq tone stacks or otherwise emulate the sound and drive characteristics of certain amplifier preamp designs (often Marshall), so you get some of that flavor with a cleaner amp, or can customize your guitar tone before it hits the amp.

A regular preamp amplifies a signal, usually from a microphone or some other source like an instrument DI that requires gain to reach a desired level for recording. Preamps often include phantom power for condenser microphones, which tend to be higher output; but preamps also can have high gain and impedance for passive high sensitivity dynamic and ribbon microphones.

A phono preamp likewise amplifies the quiet cartridge signal from a record player.

2 Likes
#60

This is relevant to my interests -tm-ā€¦ Iā€™ve been quite passively been looking for a small battery / USB powered stereo mic preamp of reasonably high quality, that would also have dual (very) high impedance inputs. I wonder, does such a thing exist?

I have a really cool acoustic instrument that has rather high fidelity stereo piezo mic system. Now that I built a Fates for myself and got excited in using it and developing stuff, thereā€™s an all new interest in building or buying something that would fit a USB-battery powered setup, and amplify the instrument enough (it needs surprising amounts of gain!) for looping, mangling and recording. As a bonus, the same box would then be a good ā€œfrontendā€ for using my bass, more lo-fi contact mics etc. with Norns / Fates.

So far it looks like the easiest option is two devices: some kind of small dual preamp USB interface that also works as a standalone device, and a DIY battery or phantom powered dual hi-Z buffer. Eg. finding one of the smaller Sound Devices boxes used, and building a pair of those single FET piezo buffers.

Any further suggestions? I saw the Zoom H4n Pro has high impedance ā€œlineā€ inputs (around 500k IIRC) but without testing Iā€™m yet uncertain if thatā€™ll be easy enough a load for a piezo pickup system with short cables, and how the preamp & input quality is like in general.

And FWIW, regarding an earlier thread of discussion: for simple That1512 based preamps, itā€™s hard to beat Dantimax ThatMic in price, at least if youā€™re situated in EU: http://electronics.dantimax.dk/Kits/Preamps_-_poweramps/11380733512.html ā€¦ For a battery powered solution youā€™d probably have to feed a suitable DC-DC converter to generate the bipolar power rails from a single supply (eg. USB, 12V battery pack, or whatever) but it doesnā€™t sound impossible.