Bass DI transformer box - Motor City Magic Bass DI Box- Passive, "MCM 004" Direct injection recording box Available on Reverb

Now available on Reverb (Or DM me for private sale)

https://reverb.com/item/34291969-motor-city-magic-bass-di-box-passive-mcm-004-transformer-direct-box-handmade-in-nyc-usa

Inspired by my hometown of Detroit, MI, the MCM #002 is my take on the passive transformer DI box which was made famous there.  This  passive DI box is handmade and custom built using the highest quality parts available: Hammond aluminum box, high quality carbon-comp resistors, Bournes potentiometer, and a brilliant Jensen transformer with excellent MuMetal magnetic shielding. Genuine Neutrik/Rean input/passthrough, Amphenol output jack, and long-life toggle switches for the pad switch and ground lift.  Providing pure Motor City Magic, it features a custom pinstripe job, and a beautiful ORIGINAL 1960's Bakelite knob.  Signed and dated inside.

Offering clarity, punch and a round, tightened low end, this unit is a bit less "fuzzy" on the high end than other popular motown boxes.  A perfect custom addition to any professional studio.

Features at a glance:

Hi-Z input for Bass or guitar with Passthrough (1/4"Jacks)

Low-Z output XLR (Male) 

Adjustable Pad (completely bypassed when switched "out")

Highest quality parts: Jensen, Hammond, Bournes, Amphenol

Vintage 1960's Bakelite Knob

Custom Pinstriping

Dimensions: 4" long x 2" wide x 2.5" tall, not including knob or switches.  Knob and switches add .75" to length and height.

#Wolfbox #Wb-3

Handmade in LIC, NY.

Ampex 601 Schematic and Mic preamp Conversion

The Ampex 601 makes a fine tube microphone preamplifier, as built.  Simply replacing most of the capacitors brings it new life for a new age in recording history.

I suggest replacing all of the electrolytic(if not now, you'll need to eventually), and whatever signal caps you like.  If the preamp already sounds great- no need to mess with it really.  In most cases, however, you'll need to replace some parts. See the video below for more:

So, I put together a revised schematic, showing exactly which parts are used, and which parts are in the audio path.

You can see that the tubes (valves) highlighted in yellow are the ones used directly in the audio circuit. Since most of the tubes are coupled to the circuit, I replace all the electrolytic caps in the entire unit.  I also replace the enourmous 1000uf/6v and .5/600v caps, just to save space(and it only costs a dollar for those parts).

One can go as bananas as one likes, adding phantom power, phase switches and DI inputs, but there is real magic in this unit as it sits.  Though the grounding is hectic, and the power supply dangerously close to everything else(possible hum), I was able to make this unit a surprisingly quiet.

Let me know if you have questions in the comments section, I'm always glad to lend a hand!

Merch for our Youtube channel, now available!

Merch for the Frank Olson Twins Youtube page is officially available now!
Click the link below to see more:

More available at link below:

https://teespring.com/stores/frank-olson-twins-merch

All designs are hand illustrated.
Thanks for watching!

Supro Thunderbolt Speaker Replacement

Today we'll replace a Supro Thunderbolt Amp S6420 original Jensen speaker with a Supro TB15.  It turns out to be a pretty good match to the vintage 1960's amp.

Let me start by saying:  If  you don't know how to properly and safely work on a tube amplifier, do yourself a favor and don't remove the amp chassis from the amp.  There are lethal voltages inside.  Don't touch anything inside the amp chassis. It's easy to replace the speaker by removing the speaker baffle, and then replacing the speaker.

As an amp tech, I wanted to make sure nothing suspicious was happening inside, so I removed the amp chassis. This also gives the viewer a better understanding of what's going on inside their vintage amp, without taking their own apart.
I begin by removing the tubes from the amp.

Then, I removed the chassis screws, and before pulling the amp chassis out of the cabinet, I removed the cabinet shielding wire screw.

After carefully removing the chassis, I can now remove the speaker from the cabinet.  This is how most speakers are removed- from inside the cabinet.  Since all the nuts were loose on the speaker lugs, I was able to remove them without a socket or wrench.

If your speaker needs a new 1/4" plug, now is the time to make a new speaker cable and install it.  Since this one had a plug soldered on, I made a new one and soldered it onto the replacement speaker.

Installing the speaker is the most difficult part and that was quite easy, actually.  You must be very careful, however to perfectly line up the screws with the speaker holes.  This takes a steady hand and some confidence.  Rushing this part will reward you with at least one hole in the edge of your new speaker. It has happened to me.

Once you have installed the speaker on the studs, you can now install your washers and nuts.  Tighten them with a wrench or socket to be sure the speaker is installed tightly.

Clean the contacts for the cabinet shield and reinstall it with the screw.
Reinstalling the amp chassis is a breeze, as long as you leave room for the amp to fit by rotating the speaker slightly to allow for clearance.  Since you did that, go ahead and reinstall the amp chassis into the cabinet.
Screw the chassis back into the cabinet with the screws you removed.

Reinstall your tubes.

PLUG YOUR SPEAKER BACK IN.

Power up your amp and give it a listen!