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500 Series Tube Direct Box (DI)
MSRP: $895

The MODEL 500TDI is a tube direct box for the 500 series format. It uses the same TrueTube™ technology that is in the popular 583S Mk2. TrueTube™ provides proper operating voltage to the 12DW7 tube so that you get rich tube harmonics and incredible detail. Two knobs allow the user to drive the tube input separate from the output for a wide array of tonal possibilities. The top input is a high impedance input while the bottom input can be used as a through OR a lower impedance input for more sound options.

500TDI Front Image


Lachapell audio 500 series modules icon
500 Series Tube DI

The 500TDI is the first properly powered vacuum tube DI for the 500 series format. Incredibly versatile, it ranges from clean to gritty, perfect for bass, keys, or other line level sources.

lachapell audio truetube power 250V icon
TrueTube™ Powered Tubes

As with all LaChapell Audio 500 series modules with tubes, the 500TDI fully powers the vacuum tube with TrueTube™ technology. Providing a full 250V without stressing or straining the power supply, the 12DW7 vacuum tube in the 500TDI operates as a tube should — Great headroom and rich harmonics with a pleasant overdrive when necessary.

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Two Input Options

The front panel 1/4″ jacks provide even more versatility. The bottom jack is a through output, but ALSO can be used as an input. Each jack offers a slightly different sound.

Lachapell Audio dual drive icon
Dual drive knobs

Separate input and output drive knobs provide you with a wide range of sonic options. Go heavy on the output knob for clean tones or lean on the input to get rich tube harmonics.

High Pass Filter Icon
High Pass Filter

The built-in high pass filter on the 500TDI is… well.. A high pass filter.

THD+N0.10% – 25% (@ +2dBV)
EIN:– 100dBu
Lachapell Audio 983s two channel rack mount tube microphone preamp (mic preamplifier) Example 1


With the Dual Drive knobs set at INPUT around 25% and the OUTPUT around 75% with the PAD off, you will get a very clean and pristine sound. The distortion is very low with no added harmonics and there is a ton of headroom. This is a great starting position for those wanting a clean tube sound regardless of the microphone type.

Lachapell Audio 983s two channel rack mount tube microphone preamp (mic preamplifier) Example 2


With the Dual Drive knobs set to INPUT 75% and OUTPUT 25% with the PAD off, you will get tube harmonics and natural tube compression.  This is a  great place to start when using ribbon or dynamic mics that need a little harmonic color.

Lachapell Audio 983s two channel rack mount tube microphone preamp (mic preamplifier) Example 3


The 583S provides great sonic versatility. With the -20 dB pad engaged and the INPUT set to around 50% you will hear a rich roundness and warmth. With these settings the mid-range will move forward and the input headroom is increased as well.



Our modules were designed to meet API’s VPR certification standards. As such, the API series of 500 series power supplies are our first recommendation. But there are others that we’ve found to be very reliable options such as the Purple Audio Sweet Ten.

This is a question that we are asked often and the answer is no. Yes there is a glowing vacuum tube in your 500 series module but it is a 9A type preamp tube. This is the same type used in the AKG C-12, Telefunken 251, etc. While these mics only have one section of the tube active, they also have less internal volume for the tube to cool and yet the surface temp of these mics never exceed room temperature. As long as you don’t block the venting that is already part of the 500 series power supply you will be just fine.

The 583S mk2, 583E, 500TDI and 500DT will get warm but nothing more than any other 500 series module drawing 110-120ma. It’s never a good idea to block or cover ventilation holes that are on top covers of the 500 series power supply.

All LaChapell Audio products feature a 2 year warranty on parts and labor for issues relating to manufacturing. The tubes have a 6 month warranty. Please see the Digital Audio Labs Warranty page for more information.

The 500TDI uses a 12DW7. The first stage, driven by the INPUT knob is a 12AX7 and the OUTPUT stage is a 12AU7. The 12DW7 combines the two tube flavors into one.

Yes. The manual will provide guidelines in this regard. The 2-bay 583’s (583E and the original 583S) have square openings that are intentionally designed to allow users access to the 12AX7 and replace with other like tubes for additional flexibility. Generally speaking, it’s the input tubes (the 12AX7s or 12DW7s) that would be replaced if you are looking to alter the sound of the amplifier. The 992’s output tubes require a critical balancing step so, for that reason we don’t recommend messing with these. In any case, if there’s ever a question related to swapping out tubes PLEASE give us a call.

LaChapell Audio has been incredibly fortunate in having a great user base. We’ve had folks like Brad Paisley, Hans Zimmer, Phil Keggy, Depeche Mode, M83 and other personally choose our preamps over others for critical productions. Many studios in Nashville, LA and the rest of the world rely on LaChapell Audio to track the sound they want.

Not at all. From the beginning we set out to not only make the first tube preamp for the 500 series, but the world’s first HIGH-VOLTAGE tube preamp for the 500 series. Think of the 583, 500DT and 500TDI as having a secondary high-voltage supply within the unit. All LaChapell Audio 500-series modules with tubes feature both a full 250 volts to the plates and a full 12 volts to the filament. This is the proper way of powering a vacuum tube and, more importantly, allows the tube to behave the way it was design sonically without stress from a lack of power.

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