Downbeat Studio

03/31/2025

Hi allI'm back with the final installment on how our Gates SA-70 preamps are crafted. Today, we'll focus on the enclosure, layout, and metalwork. We're moving a bit in reverse, as this is usually the first step in building a preamp. Lets start with parts we are going to need for a single channel preamp enclosure: Chassis Box - Hammond, Aluminum, 17" x 8" x 3"...

Hi allI’m back with the final installment on how our Gates SA-70 preamps are crafted. Today, we’ll focus on the enclosure, layout, and metalwork. We’re moving a bit in reverse, as…

03/17/2025

Two channel Gates SA-70 commission for a client. A little bit different feature set with the gain and feedback controls combined with a JLM Go-Between for the pad, phase and 48V phantom power. We got NYT transformers on the input and UTM on the output.

Went with the International power modules on this build which are great and help keep noise low.

Love the faceplate color with the pop of the red k***s.

03/12/2025

FOR SALE: $1000 shipped in US

Here we have another Gates SA-70 with all the usual controls: rotary input pad (-40/-30/-20/0), gain control, switchable bass adjust and negative feedback control. Has a DI and switchable backlit VU meter.

Inside we’ve got a favorite combo of mine; the UTC / RCA N-6565 input transformer with an Edcor output transformer. NOS Soviet oil in paper output cap. High quality caps in the signal path.

RCA 6SJ7, RCA 6C5 and KEN-RAD 6X5

Faceplate painted in a grey hammer tone with sparkle and gold specs. The pictures don’t do it justice.

NOS daka-ware k***s and new style Fairchild k***s.

02/26/2025

First time building a guitar amp. Put together this little Fender Champ and am really enjoying the sound. I’m falling for these Hammond enclosures and am debating building a preamp or DI into a similar one.

Got new transformers from Tubes and More. Tubes are NOS RCA from the stock pile.

02/16/2025

For Sale: $1000 shipped in USA

We got another Gates SA-70 preamp with a slew features packed into a 2U enclosure. The faceplate is finished in a hammered grey with gold luminescent finish.

Across the front we have controls for switchable input pad (-40/-30/-20/0), variable gain control, stepped bass control and variable feedback control. DI input. Switchable input impedance and switchable VU meter.

We have a Soviet paper in oil cap on the output. Tubes are NOS 6X5 for power rectifier, RCA 6C5 and RCA 5693/6SJ7. UTC A-10 on the input and Triad A-65J on the output. Great sounding transformers.

Please message us with any questions or if you are interested in purchasing.

02/14/2025

This one was a beast. You’re looking at a UA 175b tube compressor. I stayed faithful to the original design with a few additional features.

Leverages original UTC O-1 input transformer, UTC A-18 interstage transformer and a UTM 3580 output transformer. Combination of RCA and Sylvania tubes. for the power tube with power transformer and choke.

My two favorite features are the giant VU meter and the purple sparkle faceplate finish.

Additional features are “test” switch for setting balance, Hi/Lo input switch and 150/600 ohm output impedance switch.

Front panel k***s control VU meter input, GR meter zero, input, attack, release and output.

02/09/2025

Hello, everyone! I'm back today with part two. First, I'd like to thank you all for the positive feedback. If you have any questions about these articles or building your own Gates SA-70, please leave a comment or reach out via email or Instagram. Lets tackle the additional features of our builds. Direct Input (DI) Adding a DI is relatively easy....

Hello, everyone! I’m back today with part two. First, I’d like to thank you all for the positive feedback. If you have any questions about these articles or building your own Gates SA-7…

02/09/2025

Wired up a pair of Telefunken 1:1 line level transformers in a Bud box for .

Came together real nice. Transformer vibezzzz.

02/05/2025

Hello everyone! I wanted to share some insight on the Gates SA-70 preamp, which I build somewhat regularly. I have four of these units in our studio and have sold well over ten in the past few years. It’s a fairly basic tube design and was one of the first tube preamps I felt comfortable building after the RCA BA-2 style....

Hello everyone! I wanted to share some insight on the Gates SA-70 preamp, which I build somewhat regularly. I have four of these units in our studio and have sold well over ten in the past few year…

01/25/2025

For sale: $380 shipped in US

We have another newly built Downbeat passive DI box or Wolfbox. Same design as the Motown passive DI. This one features a UTC O-1 transformer, which is one of my favs for this build. Assembled into a vintage steel Bud box with the black crackle finish.

Switchable pad and pot on top with ground lift on the side.

Get it while it lasts.

01/23/2025

Put together a nice little 10 stereo input - stereo output passive DI for

Selection switch and vintage Daka-Ware k**b with NOS Mil-Spec ADC transformers. Blue hammertone with gold fleck on the faceplate.

01/10/2025

Just finished a Langevin 5116B rack-up for and it came together real nice. Grady had the power supply and faceplate powder coated locally in Brooklyn and I love the finish. The pictures do not do it justice.

Tube rectified external power supply for the vibe. Switchable input impedance with stepped pad and stepped gain switches.

Reach out if you are looking for any custom racking work.

01/03/2025

For Sale: $525 shipped in USA

This is my favorite enclosure I brought back from Japan, so I had to make something dope with it.

This one is a passive/tube DI. It offers a traditional passive “Wolfbox” DI path as well as a tube DI path with a flip on the switch on the front panel. This allows the unit the have two unique paths with different sonic characteristics in one box. The passive path is through the classic UTC A-11 transformer. The tube path leverages a vintage Amperex 12AU7 running as a starved plate cathode follower. This adds additional harmonic distortion to the signal and sounds awesome on a variety of instruments. Gain of tube path is a variable control on the front panel and offers roughly 10db of additional gain. The tube path also runs through the UTC A-11.

The second switch selects between 200 and 500 ohm output of the transformer. Russian paper in oil output cap on tube section. This is a great versatile DI that gives you that classic UTC transformer sound two ways.

12/10/2024

FOR SALE: $350 shipped in US

Another passive Wolfbox DI built into a Hammond amp top enclosure. Features a vintage NOS ADC transformer. Controls for switchable pad, transformer impedance and ground lift. Carbon comp resistors.

10/08/2024

FOR SALE: $1100 shipped

This was a fun project. Repurposed a Gates M3625 Gain Set enclosure into a Gates SA-70 preamp. Tried to keep as much of the original enclosure as possible.

For the transformers we have a Jensen JT-115K on the input and Edcor on the output. Tubes are NOS RCA 6C5 and a JAN 5693 (high end substitute for 6SJ7). Inside we’ve got all new components and NOS vintage caps in the signal path, including a Soviet paper in oil cap for the output.

Gates VU meter and vintage k***s. Upper left switches are a phase, insert pad control and VU range. Controls are a Daven stepped attenuator for the pad, variable gain and feedback controls and a 6 stepped bass control that switches the caps in the feedback loop. The feedback and bass control offer subtle changes to the frequency response. There is also a DI.

External tube rectified power supply for lowest noise possible.

Great table top SA70 preamp!

09/06/2024

For Sale: $800 shipped in US

This is a new build for us. You’re looking at a Langevin 5116B circuit leveraging a UTC CG-134 on the input and Edcor push-pull output transformer. NOS GE 12BH7A and Mullard 12AX7 tubes. Solid state power supply.

Backlit VU meter with controls for stepped input pad (-40/-30/-20/0), variable gain and meter kill switch.

These are great sounding preamps and have heavy 2nd harmonic vibes. The pad allows for line level signals to be passed through the unit to add “color.” The variable gain is controlling the resistance in the feedback loop so you will notice a low end bump with lower gain and more flat frequency response at higher gain. You can dial in unique sounds by playing with the pad and gain control on your sources.

Unit comes with power cable.

The faceplate is custom painted in black metallic with gold spray over and drips. Sealed up nice with a few layers of polyurethane.

Message with questions or to purchase.

06/10/2024

I was finally able to find time this week to install the CAPI ACA and Booster board. There were a few items to take into consideration with changing the master summing circuit: - The MCI has 10K summing resistors and the CAPI ACA is setup for 47K summing resistors. Therefore I had to adjust the feedback resistor and corresponding capacitor for the 10K resistors....

I was finally able to find time this week to install the CAPI ACA and Booster board. There were a few items to take into consideration with changing the master summing circuit:- The MCI has 10K sum…

05/29/2024

About a year back, I acquired an MCI JH-618 console from Reverb to replace my custom small-format Quad Eight summing mixer (pictured below). My aim was to find a unit with enhanced routing capabilities, inline mic preamps, and EQ. I had been reminiscing about our previous console, the Sony MXP-3036. The JH-618 offered many similar features but in a more compact design....

About a year back, I acquired an MCI JH-618 console from Reverb to replace my custom small-format Quad Eight summing mixer (pictured below). My aim was to find a unit with enhanced routing capabili…