LaChapell Audio 503 500 Series 3-Band EQ  From LaChapell

An impeccably clean and detailed 500 Series EQ module featuring identical circuitry to the EQ found in the 583e pre/EQ module.

LaChapell Audio


Retail:  $895.00

"Experience the Difference"

Try Before You Buy

Try Before You Buy
Call us now to set up a free trial in your home or studio: 888-528-9703. Our specialists will help you select the best fit for your needs and hook up your free trial for the ultimate peace of mind. Experience the Sound Pure difference!
View all eligible products »

Sound Pure's 3-Year Warranty

Our Free 3-Year Warranty!
In addition to the standard included manufacturer warranty, virtually all new products carry our exclusive, industry-leading, absolutely free, Sound Pure 3-Year Warranty, which includes PARTS & LABOR. This high-value perk is our way of providing the ultimate in added value to enhance the unique personal touch our small, dedicated team contributes to each purchase.
Learn more »

Lifetime Support

Free Lifetime Technical Support!
Our small team of dedicated experts is here to help the original purchaser for the lifetime of the product. Why? Because we care about building real relationships with our customers for life and stand behind every product we sell.

Free Shipping

This Product Ships Free!
Products ship from our well-located, climate- and humidity-controlled warehouse absolutely free (inside the continental USA). Low-cost international shipping options exist for most products.
Contact us for details »

No Sales Tax Outside North Carolina

Ships Quick!
Usually ships 3 - 5 business days after order processed.
Payments as low as $61/mo.

What We Think

The 503 EQ features indentical circuitry to the EQ section found in the LaChapell 583e preamp + EQ module, in a standalone single 500 series module. Being that it was originally designed to compliment the rich tube tone of the 583 preamp, the 503 EQ boasts a pristine and open tone with meticulously designed filters for optimal signal clarity. In use, the 503 paired beautifully with a cleaner preamp on classical guitar for a pristine and transparent recording chain. To get a completely different sample, we also used the 503 on a saturated bass track to beef up the low-end and bring out a little more pleasing "woodiness" within the mid-range. We were astounded by the tightness of the low-end - even at more extreme amount of boosting. The pristine tone of the 503 allowed all of the original harmonics to remain untouched, but allowed us to easily bring out more definition and clarity by boosting the mid-range fundamental by a few dB. The addition of high and low-pass filters was excellent for tracking a handful of electric guitar tracks, as we could EQ out the very top "hiss" of the amp and eliminate that low-end rumble that begins to eat up your converter input's headroom. 
The 503 is an excellent 500 series EQ choice when upmost clarity, transparency, and detail are desired without any additional coloration. 

Manufacturer's Description from LaChapell

The Model 503, like its counterpart found on the 583e, offers up very low distortion signature and minimal phase deviation; it is an extremely clear and transparent EQ design. Additionally, we’ve added some capabilities to the 503 not found on the 583e, specifically:

      • Cut/Boost range increased to +/- 12dB
      • Low pass filter at 5k & 10k
      • High pass filter at 50hz & 150hz
      • +/- 6dB overall trim gain stage

LaChapell Audio

About Manufacturer

With the 992 you have the option of choosing between two unique input topology configurations. Standard 992: Featuring a transformer-less balanced differential input utilizing two USA made 6072A's per channel along with twin matched 400v caps. This configuration provides >50dB of gain (usually about 52db) with a typical non-weighted EIN of -114 to -116dB. Extended Gain 992: By replacing the input caps with the Jensen JT-115k transformer and exchanging the 6072's for the timeless 12AX7/ECC83 this variant is able to provide a generous >74dB of raw internal gain with a typical EIN of -124 to -126dB referencing 150ohm. The direct instrument input (Hi-Z) on both variants utilizes a high performance Jensen direct transformer which feeds the balanced differential amplifier input. In operation, the user has individual control over the input and output gain stages of each channel. This provides uncommon flexibility to delve into the 992?fs broad sonic pallet making it one of the most versatile preamplifiers in any environment. Push the inputs hard and capture that elusive air that can only come from fully balanced tube gain. Or, pull the inputs back and favor the output stage for a cleaner, more linear signal - the choice is yours. Output signal strength is easily monitored through an isolated Sifam back-lit VU meter. There are also five illuminated toggle switches per channel for Meter On/Off, 48v (Phantom), -20db input pad, phase reverse and Mute.


  • 3 Band EQ with fully sweeping frequency control; fixed 'Q' value of 1 with very low phase deviation
  • Input/Output Type: Transformer-less; Ultra clean with minimal harmonic signature
  • Input: 40k
  • Output: 50ohm
  • Bands:
    • Low 30hz - 400hz
    • Mid: 325hz - 5khz
    • High: 2.5khz - 20khz
  • Cut/Boost: +/- 8dB
  • Max Input: +24dBu
  • Max Output: +26dBu
  • Self Noise: -93dB
  • THD+N: 0.012% (with +8dBu input signal)