48-month financing with the Vintage King Credit Card
Save on the Best in Pro Audio New Deals Drop Daily
Sorry, this product is currently unavailable. If you're looking for something that will be of a similar fit in your studio, please contact us using the methods below.

API 550B EQ (Used) – No Longer Available

Discrete 500 Series 4-band EQ

Product Description

Based on API's original 550 from the late '60s, the API 550b is a continuation of the EQ that played a major role in the history of music recording, but with an additional filter band and several new frequencies. Incorporating API's exclusive circuitry and proprietary components (such as the legendary API 2520 Op Amp), the 550b artfully blends the past with the present. So many hit records still depend on the unique 550 sound that engineers around the world find it to be an invaluable tool. In fact, the 550b design has been taken from the original blue prints and spec control drawings from the API archives. It is unlike any other EQ you will ever use.

Rather than offer a huge assortment of complex features, the API 550b provides exactly the right number of controls. Its four EQ bands are overlapped significantly to aid in dual roles as problem solver and sweetening device with each band offering seven switchable filter frequencies that span four-to-five octaves. These frequencies, purposely selected to be musical rather than numeric, were selected by an experienced "who's who" list of the industry's most proficient engineers.

Making use of API's "Proportional Q," an innovation designed by Saul Walker in the '60s, the 550b intuitively widens the filter bandwidth at minimal settings and narrows it at higher settings without the need for additional bandwidth controls. This unique feature minimizes the "phase-shift" sound found in many equalizers. In addition, the reciprocal nature of the 550b enables the user to "undo" what has been done previously with exact precision.

The benefits of the API 550b are most obvious to those who work with EQ on a continuous basis. If major tonal restructuring is required, the extraordinary headroom made possible with API's 2520 Op Amp offers the predictable and warm analog performance, even under duress. With a surprisingly wide range of tonal variations, the 550b is an invaluable and professional audio tool with great flexibility and excellent sonic ability.

Features

  • Four bands of classic API equalization
  • Each band offers seven API selected frequency centers
  • Reciprocal and repeatable filtering
  • 12 dB of boost/cut per band
  • EQ band 1 and 4 offer shelf/peak switching
  • "Proportional Q" narrows filter Q at extremes
  • Traditional API fully discrete circuit design
  • High headroom +30 dB clip level
  • Re-issue of 1967 API 550 EQ with an extra band

Product Specifications

Condition Used / Vintage
Tube or Solid State Solid State
Channels Single-Channel
Chassis 500 Series
Module Type 500 Series
Module Slot Count 1 Slot
Digital I/O No
EQ Type Parametric

Product Reviews

No one has written a review yet. Be the first!

* Required Fields

Share Your Opinion

The best gear advice always comes from those who use it the most. That's where you come in! Let the pro audio world hear your voice with a review of the API 550B EQ (Used) . Once you submit your review, please check your email and verify your address to have it posted.

How do you rate this product?
I would like to thank VK for the wonderful sales assistance, service and prices. This was my first purchase with you and it won't be my last. I only wish I'd discovered you years ago!
Matthew R.
I had two Grammy wins this year - Ray LaMontagne & Carolina Chocolate Drops. Both made with help from Vintage King!
Ryan F.
In almost 20 years in Pro audio buying, never did I receive a unit so well packed and exactly as described. Works flawlessly. The whole process has been so smooth. I will never hesitate to do business with you guys in the future and will recommend you to everyone I know.
Martin C.
This was my first experience buying something from Vintage King (although I surf the "used" categories on the website frequently!), and, despite being on the other side of the world, I had absolutely no trouble and everything went very smoothly.
Phil T.
The speed of delivery exceeded my expectations! I was VERY pleased that my shipment arrived in time for a scheduled vocal tracking session. The packing insured that my order arrived safely. And the sales staff responded quickly to questions regarding the product.
James P.
Thank you so much! Vintage King has been so fair and easy to work with. I can't thank you enough. It feels good to trust such a hefty purchase to folks who are so helpful and knowledgeable. Vintage King is a sound designers dream store.
Noa L.
You guys have excellent customer service and I am excited about the next upgrade I complete on my fifth recording facility. I've been in the studio business for forty plus years. The salesman I worked with at Vintage King was the best of the best. You all rock!
Robby T.
I would recommend Vintage King to any one looking for top-class gear, unbeatable customer service and the best prices on the map!
Jake D.
My experience with Vintage King was excellent. The order was here fast considering it was out of stock. The sales person had SKB send it to me directly and I couldn't have been more pleased.
Michael D.
From the minute I placed my order I was kept well-informed through each step in your process. Even though I was buying a comparatively modest piece of gear, your attention to detail made me feel like I was purchasing a six-figure mixing desk.
Thomas W.
I am a new customer of yours. You guys provided me the absolute best deals in ordering all the equipment to power my brand new recording studio. Your customer service is amazing and i will always deal with you from here on out.
Rob M.
Thanks for your great service and getting this out today. You guys really are the Kings!
Alan B.
Better than expected! Truly impeccable service. Your team was professional, knowledgeable, provided speedy delivery above and beyond standard. Vintage King Audio is definitely my go to for all of my audio and information needs.
James O.