Specialized D.I. Boxes. / Instrument preamps

Started by Elantric, January 10, 2018, 10:30:48 AM

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Elantric

Specialized D.I. Boxes.
---------------------------

LR Baggs Venue is very handy and clean!
https://www.lrbaggs.com/preamps-di/venue-di-acoustic-preamp
Features
Adjustable gain for both passive and active pickups

5 band EQ with tunable low-mid and high-mid bands

Garret Null notch filter for effective feedback control

Phase inversion for best sound and feedback control

Full chromatic tuner with footswitch mute/tune function

Adjustable volume boost footswitch

Full isolation audio transformer couple DI

4 segment clip meter to visually optimize gain setting

4 segment battery status gauge

XLR and ¼" outputs

Series FX loop (separate jacks for send and return)

Works with 9V battery or DC adapter (not provided)


These are very popular and very clean

Elantric

#1
Headway EDB-2 Direct Preamp

http://www.headwaymusicaudio.com/product/edb-2/

Specifications
Comprehensively packed with practical and effective sound crafting features:

Twin channel with individual inputs & gain controls
5 Band EQ assignable to Channel 1, 2 or both
Notch Filter assignable to Channel 1 or 2
Huge 0-32 dB Gain to interface with most mixers/desks etc
Phantom Power is assignable to either "ring", "tip", or XLR to power virtually all instrument microphones/pickups.
Phase Reverse assignable to each channel
Earth Lift Switch
"Range" Switch tuned for specific instruments i.e. Violin, Guitar, Bass etc
iPod Input for backing tracks, practice routines etc
Mute Switch
Mono, Stereo & XLR Inputs, Jack and XLR Outputs
Battery or Mains powered (power supply included)

http://www.headwaymusicaudio.com/wpcms/wp-content/uploads/EDB-2-Manual-FINAL-14.05.2013.pdf





This one is a swiss army knife - trivia - works well with a TRS cable for using a stock Gibson ES-345 Stereo Guitar into a mono guitar amp. 

Elantric

#2
https://www.amazon.com/Dean-Markley-PLUS-Guitar-Amplifier/dp/B0002J157G/

Dean Markley (UltraSound) DI PLUS Guitar Amplifier Preamp/DI
"The ULTRASOUND DI Plus is a very powerful tool for any musician. This is not only a DI but a full featured preamp designed after our famous AG-series amps. Whether at a local open mic night or at a major concert venue, you will be able to dial in the clear natural acoustic sound that our amplifiers are known for, and route it to the stage PA through a balanced XLR output. Sound engineers will appreciate the versatile controls and the optional 48-volt phantom power operation. Therefore, no more wall warts or batteries if your mixer has phantom power. (Originally called ULTRA PDI.)

This is used by David Lindley - for canceling feedback on his acoustic slide guitars

Elantric

#3

Elantric

#4
http://www.gmarts.org/html/gpi.htm
Guitar Preamp Interface (GPI)
© Copyright GM Arts 1996-2004


Overview
The GPI sits between your Guitar Preamp (such as a POD) and your Power Amp. It's purpose is to allow connections for many typical stage setups, and allow minor tone adjustments on the fly to suit different acoustic environments. It can be built in mono or stereo, and has separate outputs for FOH and your Live stage rig. There are two independent tone sections designed for tone fine-tuning (not massive tone shaping).

The first tone section has Deep and Bright controls, designed to roll off extreme lows and highs. This can be used for the DI send, your Live sound, or both. This can be used to send a more "guitar-cab-like" signal to FOH, and for minor tweaking of your model patches.

The second tone section has Treble & Bass controls, and affects your Live sound only. It allows you to overcome Fletcher-Munsen issues by setting them high for tweaking patches at low volume, then set them flat for louder live playing (or adjust them as necessary if your patches still aren't quite right at higher volumes).

An Aux input can be used to add other audio to your Live sound, useful if your live sound is a personal monitor. The unit also houses a power supply for your modeller.

!!! WARNING !!!
This design includes mains wiring. I urge you NOT to build this yourself unless you are absolutely certain you understand all the risks, and necessary precautions to build and operate this device safely. Only one mistake can cost your life or the life of someone close to you. If you're lucky, it will just burn down your house. If you're not completely sure, arrange to have it built for you by a qualified technician.

My mini rig:

The controls are now labelled - left to right, they are:
Deep, Bright, DI filter switch, Live filter switch, Bass, Treble, Aux level, Live volume (and the pilot light).


Front Panel Controls
Live Volume
- up to 14dB boost, useful for driving power amps with low sensitivity

Live Bass and Treble
- allows you to globally adjust your patches for different room acoustics
- set these high when tweaking patches at low volume, so your patches are balanced when these are flat at high volume
- these controls intentionally don't have a wide range (+/- 6dB at the extremes of 80Hz and 5KHz). They are intended for fine adjustments, not massive tone changes.

Aux Volume
- allows you to mix other signals with your live sound, such as a vocal send (useful if your live sound is a personal monitor)
- not affected by Bass or Treble
- doesn't go to the DI Send

Deep & Bright
- these controls can be switched on for the DI Send output, or the Live output (or both, or none)
- with the controls fully clockwise, your sound is unaffected (flat response)
- turning either control down rolls off extreme highs and lows, like a typical guitar speaker
- this is useful for DI send if your mixer is ruining your tone with excessive highs or lows
- also useful for DI send as a neutral speaker/mic simulator when you're using the POD in live mode
- can be switched for Live sound to check what's being sent from the DI, or for some finer Live EQ control
- the Bright control, used with your modeller's speakers sims, can smooth out fizzy top end common in these devices
- through a normal guitar cab, the top half of the control range of these controls is not likely to make much difference, however, the effect is very audible through a full range system

On The Back

Input (2 for stereo)
- This input is balanced (so you can use a stereo cable from your POD output), or an ordinary mono cable

Aux In
- This input is also balanced, and has no signal ground connection
- Either a stereo or mono cable will work, and not cause earth loops
- If the GPI is built as a stereo unit, with left and right channels, an Aux Send switch can send Aux to L / L&R / R

DI Send
- Your input signal can be sent to FOH from here
- The bandpass filter can be used or bypassed for DI Send
- Aux Input does not go to DI Send
- Live Volume, Bass and Treble controls do not affect the DI Send
- Earth Lift switch can connect or disconnect the signal earth (set to LIFT if you have an earth loop)
- Phase switch can reverse the DI Send phase if you have phase problems between your live amp and monitors
- The DI Send is mono (a stereo GPI mixes L & R inputs for the DI Send)
- A short in the DI cable will not kill your live signal
- Any interference in the DI cable is not injected back into your live signal

Ouput (2 for stereo)
- This is an unbalanced output to go to your live amp (use an ordinary guitar cable)

POD Power
- This is a power supply outlet for your PodXT (you'll need a short power patch cable)
- Isolated from the GPI preamp power, so there's no chance of damage to your POD or the GPI

Mains Connector, Power Switch and Fuse
- Fuse is 125mA for 240V, or 250mA for 110V
Here's an overview of the signal flow:


Grounding: The case of the GPI is connected to mains earth (as should any powered metal box!). The signal earth is not connected to mains earth in the GPI (but of course it's connected from Input to Output). The DI Send has an earth lift that can connect or disconnect signal ground to the DI cable shield. Mains earth should be connected to signal earth in your power amp for safety.

General Building Advice: There's only moderate gain in this design, so stability in unlikely to be a problem. However, take the usual precautions, such as keeping audio connections as short as possible, and away from AC wiring. Make sure mains wiring and transformers are secure and properly insulated. The metal case should be connected to the mains earth, but not the signal earth in this design. So make sure that ALL sockets are insulated from the chassis. Many of the pots carry the signal alone, and/or bias for the ICs, so avoid the really cheap "mini" pots.


The Schematic
You'll need to work out how to build this yourself, because I cannot provide a PCB layout, parts, kits, etc.


Operation: Leave your POD output volume set to a high level (8 to 10), and control the volume from the GPI; that way you don't change levels sent to FOH. Start with the controls set neutral (so Deep and Bright set to max, DI and Live switches set to bypass, Bass and Treble set to mid-way, and Aux and Live volumes set to min. Here's how to connect your GPI:


History: I've built the GPI many times now to develop it and to suit different preamps and power amps. The current version is designed for the PodXT, and any power amp (flat monitor system, guitar amps, etc). New to this version:

Power supply for PODxt (9V AC @ 2A)
Catered for stereo build (mine is still mono)
Reduced high cut in the LPF bandpass from -24dB/oct to -12dB/oct (the PODxt speaker sims provide the rest)

Legal Stuff
I supply a schematic and time permitting, general advice. I cannot supply PCB layouts, kits, parts, support, or guarantees. I do not take any responsibility for any damage caused by the building or operation of this design. This GPI is © Copyright 1996-2004 , but anyone is welcome to build it for their personal use, or have someone build it for them for a reasonable "parts & labour" fee.

Elantric

#5
http://www.rolls.com/product.php?pid=PM351



https://www.vguitarforums.com/smf/index.php?topic=10315.0
PM351 Personal Monitor System
Rolls » Headphone Amplifiers and Personal Monitor Systems »
The PM351, like its predecessor the PM350b, is a personal monitoring device with a 1/4\" TRS stereo/mono Line Input,a single XLR Microphone input and hard-wired XLR pass-through, and a 1/4\" stereo/mono Instrument input with two transformer-balanced and isolated XLR Outputs. All three of these inputs are also routed via individual Level controls, to a 1/4\" and an 1/8\" (3.5mm) Phone Output. The Mic Through, and Instrument outputs have jumpered Ground Lifts for elimination of ground hum. The PM351 is ideal for live bands and church musicians, as well as studio musicians and singers. Having the ability to monitor a main mix along with the musician\'s voice and their instrument make the PM351 an effective and versatile tool.

Larger ImageManualSchematic DiagramView this Product on YouTube
PM351 Personal Monitor System
1/4" TRS stereo/mono Monitor Input
XLR Mic Input w/pass-through
1/4" TRS stereo Instrument Input
All mix to 1/4" and 1/8" Outs
Individual Level controls
Stereo balanced Instrument DI outs
Hookup www.rolls.com/apps/pm350bconnect1.jpg
Specifications
Max Input Level: -20 dB XLR, +40 dB Line, +15 dB Instrument
Instrument Input Impedance: 50K Ohms
Instrument Output Frequency Response: 10 - 30 kHz +/- 3 dB
Output Impedance, Headphone: 10 Ohms
Output Impedance, Instrument: 2: 100 Ohms balanced
Gain: 20 dB 1/4", 50 dB XLR
Headphone Frequency Response: 20 - 20 kHz
Power: 9 - 16 VDC
Size (W x H x D): 4.5" x 3.3" x 1.5"
Weight: 1 lb (.45 Kg)
Current drain 25ma nominal no signal 15vdc

admin

#6
https://www.eventideaudio.com/products/accessory/mic-pre-fx-loop/mixinglink
















https://s3.amazonaws.com/com.eventide.downloads/Product+Manuals/MixingLinkUG.pdf

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MixingLink

High quality mic pre with FX loop in a compact form factor
A stompbox size audio toolkit for on stage, in studio and everywhere in between. Includes a quiet high gain mic-pre, 48V phantom power and enough I/O and control for applications such as FX Loop for microphone signal processing (vocals, horns, strings, etc) , signal splitting and combining, complete re-amp setup, impedance and gain matching, mixing and more.


FX loop send and return supports balanced and unbalanced signals - interfaces with consoles or guitar pedals easily

Latching or momentary footswitch control of FX loop for performance effects
Works with a wide range of microphones including condenser and ribbon mics with up to 65dB of clean gain
Aux I/O connection supporting stereo input and send
Guitar amp output and headphone monitor output with separate master volume control


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A Swiss Army Knife for Every Application


Use the MixingLink as a compact studio mic pre for recording with Pro Tools, Ableton, or any other D.A.W.

   


Use the MixingLink to connect a microphone to your favorite stompbox(es) to add effects to your vocals.



Use the MixingLink as a hotel practice amp.

   


Use the MixingLink as an A/B Box to switch between two instruments.



Use MixingLink to split and bend one instrument between two amplifiers.

   


Use MixingLink as a mixer to connect multiple sources to an amp or headphones.



Ultimate Versatility


International universal power supply included
Operates on 9V battery (no phantom power when operating on a battery)
48V phantom power for condenser mics
Balanced XLR output which supports DI and line levels
Instrument and balanced line level inputs
Versatile mix control supports 3 modes
100% Dry w/FX blended in
Mic/FX balance control
100% FX (no Dry)