Ampex 602 2 Ch Brute Force Preamp Conversion

Ampex 602 Tablebeast Modified TB-602A 2CH Brute Force Preamp:

Here is my latest Ampex conversion. I tell you what, the Brute Force circuit really loves the 602. While the 601 and the Akai/Roberts monoblocks make amazing foundations for this circuit themselves, there is just something about the 602 that outshines them in my opinion. I think it may be the solid state high voltage PSU or the DC heaters that give it that inky black noise floor. It is a such a 3D sound that you wind up with something that sounds finished the way it does when you hit tape just right. But the best part is that it doesn't have the tape hiss or the hassle of messing with those aging machines. With this unit you get a brand new set of electronics built from the ground up with all new wiring, caps and resistors while using the best vintage parts to fill it out. I am very proud of my design and so far everyone who has been lucky enough to get one of these from me has been head over heels for them. Get one while you still can. Here are some more pictures.

Now Taking New Orders to Fund the Station

Tablebeast Modified Akai Roberts TB-2XP1 Preamp and 2x TB-A436 Vari-Mu Compressor:

 If you like this blog and would also be interested in getting something like what you see here for yourself, then now is your chance! I am beginning production on gear builds for the fundraising phase of the station. So, after a few months of catch-up on pre-XMFR orders, I have now have limited time available for new orders. Available will be my regular turn-key devices: (Akai / Roberts monoblocks, Magnecord PT6-J, Ampex 600, 601, and 602), trade-in orders (where you send me the donor to modify), and custom orders (pretty much anything under the sun: Bogen, Knight, Masco, LaFayette, Magnasync / Moviola, Heathkit, Dynaco, Sony, Teac, etc.) As you can see here on this blog, I make these old relics into new beast in the form of: guitar amps, microphone preamps, hi-fi stereos, audio effects, synthesizers and more. I can install add-on transformers of nearly any type as long as it fits the donor from brands like Jensen, Cinemag, Sowter, and Shure. I'd prefer to focus on what I am familiar with (which is a lot as you can see), but I am always looking for a new adventure as well. So let me know what you've got! Prices start at $399 for full rebuilds and can go on up to much more depending on the complexity of the mod and cost of additional parts. So, if you like something you see on this blog, drop me an e-mail at ::: xfmr AT xfmr DOT org ;;; and we can discuss what you're looking for.

Ampex 601 2 Ch Brute Force Preamp Conversion w/ Altec Iron

 Tablebeast TB-A601 Ampex 601 2 channel with Altec 4722 and 15095:

This is my new king of the hill. What an awesome, AWESOME preamp this turned out to be. I started with an Ampex 601 reel to reel tube electronics module. I then gutted and dismantled the whole thing. I separated the parts from stuff I planned to reuse and stuff I planned to discard. Of the discarded some parts, some are kept for other projects and spares while others are just thrown away. Sprague bumblebee caps? Yeah, I keep those when the values are not right for the conversion, you bet! Old cap cans and ALL the wiring? In the garbage it goes!
The next step is to prepare the chassis for my intended design. I rearrange the tube sockets in my needed layout and add a few sockets as needed. Then I install the new Weber cap cans with mounting brackets. The back panel gets all the Switchcraft chassis-isolated jacks, XLR input and pad/phase switches for channel 1 and pad phase switches are also added to the channel 2 input on the front.
When considering iron for this unit, I chose some of my favorite affordable and readily available vintage transformers. The Altec 4722 and 15095 were what I went with. I wired the inputs so that they will take the 4722 of course, but it will ALSO accept a 15095 or 15335 as an input depending n application. The outputs get 15095 plugs, but can also accept 15335 units as well. This makes the octal plug-in format function as Altec originally intended, where you can swap out the transformers easily to modify gain staging and impedance matching depending on what you stuff in there. Oh yeah, they also sound freaking INCREDIBLE!
The tubes in here are the 5879 Pentode for preamp duties, 12AU7 for line amp/output duty and the classic 5Y3 providing voltage rectification. They are set up as a pair of my Brute Force preamps which have insane amounts of gain. They are perfect for ribbons with low noise and the high gain, but really I have yet to find a mic that I don't like with it. Of course you can just turn the gain down when using a hot mic and if that doesn't get you in the sweet spot, engaging the pad and turning back up will get you there.
The inputs and outputs give you a LOT of different options. Of course it has balanced XLR inputs for mics and 1/4" DI inputs for instruments or other hi-z sources, but this unit also has dual outputs per channel. One output is tapped before the output transformer and is connected to an impedance balanced TRS 1/4" output jack. It can be used simultaneously with the transformer balanced outputs that are also on TRS 1/4" jacks. Now the impedance balanced outputs are HOT and I LOVE hitting an actual tape machine with this output as it will roast that tape if desired. The transformer on the output has a stepdown that knocks the signal down while balancing and adjusting impedance as is my preferred output for getting maximum coloration as it allows yo to crank the circuit a bit more.

Projects Out the Door Before the END of the World!

OK, well, it didn't happen, but I was still determined to get certain projects out to folks before the Mayan deadline for our civilization, JUST in case!

Pair of Tablebeast 2xPre TB-2XP1 Microphone Preamplifier:

First up is a four channel set of mic pres that I was sad to see go. These are outfitted with Jensen inputs, have impedance balanced outputs, and were stuffed with some very special tubes. All four have GE 12AU7A tubes on the line amps, but the bottom pair has some fantastic German-made RFT EF86 pentodes and a GE 6X4 rectifier instead of the normal NEC-made valves that the I normally install. The first two channels do have these NEC tubes and they are simply fantastic of course, but the RFT and GE in the second pair just seem a bit more magical. Also, grainy pics I know. I took them at night in a hurry before I boxed her up. The apocalypse waits for no one.

Tablebeast TB-HR16, a Modified Alesis HR-16:

 This is a bit of a rare bird these days, at least in my hands. I don't do much circuit-bent stuff any more, but when tempted with this Alesis I couldn't resist. This is a fantastic drum machine even without the mods, but it takes to the patchbay style mod so well it almost seems like a shame to keep them stock. I hadn't done one of these in years, but it all came back once i started and I am very please with the results. Now that I have become familiar with what the guts of this guy actually ARE, I am really impressed with this advanced-for-the-time drum computer. So impressed that I am on the lookout for one of these to keep for myself. Oh yeah, the back panel for this guy was missing when I got it, so it got some hand labels on there. I was bored and there was an empty space ont he face, so it got a little unplanned beast drawing. What the heck.

Tablebeast Pre+Amp TB-PPA1-R 3U Rack w/ Jensen:

This is a rack mount Pre+Amp. Of course I have built dozens of these by now, but this one was particularly cool. It had the Jensen inputs which I just can't say enough good things about. Don't get me wrong, I love the Shure inputs that I usually use. They have a great utilitarian quality that I try to compare to denim when folks ask me to explain the difference between the Shures and the Jensens. What do I relate the Jensens to? Silk of course! So the Shures are jeans and the Jensens are a kimono. The Jensens really are smoother and less aggressive so I think it is a decent comparison. Being a man of many tastes, I like them both in any case. Anyway, this unit was awesome and is finally on the other side of the pond and hopefully in its new owner's hands by now. Enjoy!

My Newest Akai Roberts Mod Creation: The Pre+EQ

Akai / Roberts Pre+EQ Mod:

About a year ago I started messing with some EQ circuits for a new design that incorporated a microphone preamplifier and an EQ in one Akai donor module. I knew that for the preamp part of the device I wanted something totally different than my Brute Force Preamp, so I settled on the mic preamp circuit from the old Tube RCA Broadcast Consoles. It uses two 12AY7/6072 tubes and the circuit I prototyped years ago sounded great. It really is a completely different tone than the Brute Force, so it fit well with my plans. SO, for the EQ I wanted something a bit different: not the same old boring Pultec style for me. Instead I wanted to find the best PA-Style, 'James', 2-band EQ. I also wanted to incorporate some tone switching and a variable low cut filter. What I settled on was a hodge-podge of circuit bits. I used most of the 2-band circuit from the Bogen MXM mixer, a simple variable low cut circuit found on the net, a boost switch that moves the frequency band of the treble control down into the mid range a bit, and finally a 'Beef' switch that removes the negative feedback from the circuit and adds bypass caps to two cathode resistors simultaneously. I will post more details and a final schematic soon.

Tons of New Designs Brewing

Don't worry, folks! I may have recently moved to the very edge of the Green River Gorge, but I have not yet fallen off the face of the Earth. I have so much new stuff that I have been brewing that I just can't WAIT to share it with all of you. New Akai / Roberts, Magnecord, Tape Delay (Ampro and Webcor) designs are simmering while I close out my waiting list for 2012. Look for some BIG moves come January! Pictures? Well,  I do have pictures of my new place and my new tractor, er... truck.