Heads up to anyone considering buying Sovtek EL84 tubes... I'm building a stereo Hi-Fi tube amp for my home and decided to save some money by utilizing as many things in my stash as possible.  I had a brand new pair of Sovtek EL84 tubes from several years ago (probably from a guitar amp I re-tubed for someone and maybe they changed their mind about the tubes and wanted something better, IDK).  Anyway, I needed a second matched pair so I could use them in my hi-fi amp.  I first ordered a pair from www.tubesandmore.com and tested them when they came in.  Much to my amazement, the grid leakage test for the tubes did not go over very well.  While they passed this test, it was not by much.  I contacted the store and arranged for an exchange, citing the test results.  The next pair came in and I tested them.  I was blown away when one of the tubes actually failed the grid leakage test!  Can you believe this?  A brand new tube actually tested bad.  Frustrated, I returned the tubes for my money back and took my business elsewhere.  I went to tubedepot.com, who I have purchased many tubes from over the years and never a problem once.  When I placed this order with them, I cited in the customer comments section of the order my terrible experience thus far and asked if they could please check the grid leakage before shipping the tubes to me.  When the tubes arrived I tested them again.  The first tube passed everything with flying colors and I was starting to feel relieved, until I tested the second tube.  During the grid leakage test this tube become unstable and began to read in the "?" area of the test range, which for all intents and purposes indicates a bad tube.  Are you freaking kidding me?  I specifically asked for the grid leakage to be checked before shipping these.  I'm sending these tubes back and asking for my money back.  This time I will cut my losses and buy a quartet of much higher quality tubes in hopes on not having to go through this crap ordeal anymore.  

I'm not sure who is at fault here, but I suspect its a pile of fault starting with Sovtek and ending with the dealers not testing there tubes sufficiently before shipping them.  If I didn't have a tube tester I would be a victim of tubes that failed within a month or less, leaving me in a situation where I would have to buy more tubes and if I was a person who didn't know how to bias my amplifiers I would also have to pay to have a tech do that work for me each time.  What a nightmare.  Word to the wise, Sovtek tubes are garbage and the stores don't do extensive testing, so buy the good tubes and you'll be okay.    

After building 4 completely different preamp topologies and several variations of each (roughly 30 total design variants), I finally found "the sound."  I have been searching for this sound for a while, so its a huge sigh of relief having now found it.  I'm not sure what the preamp will be called, but its still a long ways off from production.  This is a 2 tube per channel design, which uses a 12AU7 (same tube as used in LBA FX pedals) and a 6922.  It has an external power supply with a secondary solid state regulated supply for the tube heater filaments to ensure the lowest noise possible.  The preamp currently has so much gain (clean boost) that I have to consider it overkill.  I'm sure it would work great for ribbon mics, but it has a bit of noise that I'll need to clear up first.  One of the topologies I tried out had roughly the same amount of gain, but better control over the gain and practically no noise.  While this other topology had these benefits, it didn't have "the sound."  This sound I speak of is the elusive magic tone that sounds extraordinarily life-like and fluid.  It sounds beautiful, with a dark background, and immense imaging.  I really wanted to capture a well balanced frequency response, which in itself has proven to be no easy challenge.  A very well known and highly regarded $2K+USD name-brand solid state preamp was used as a reference point for my tests.  I could have easily based my testing against another tube preamp, but I felt this preamp needed to have a very fast slew rate to have the modern characteristics I was after.  That said, this preamp is incredibly fast and articulate for a tube preamp.  It has the big body and musical tone of a tube pre, with an incredibly fast slew rate that comes close to solid state's ultra fast response.  I wanted this fast characteristic so the preamp could effectively be used on drums without sounding too mushy or vintage.  It was no easy task to achieve this, which is why I went through so many different preamp designs before reaching this one.

A lot of work is still needed to completely iron out the design, but when complete this will be an all inclusive dual channel preamp solution.  Input and output volume controls, front panel DI inputs, analog VU meters, phantom power, switches for low cut, phase reversal, mic/line inputs, and probably the variable & bypass-able treble roll off control from the 1401 stereo mic preamp.  I hope to be able to offer this hand-wired wonder for around $3,000 USD when complete.  The target release date is December 21st, 2015, but that is not yet set in stone, nor is the price.  Name suggestions for this dual channel tube preamp are now being accepted.  If you suggest a name that I end up using, I'll offer you a special discounted price and dibs on the first production model if you want.   

This past Thursday I shipped a Flux Bender out to Mix Engineer, Ronan Chris Murphy, who will be reviewing the Flux Bender on his youtube channel, Recording Boot Camp.   If you haven't read the May issue of Recording Magazine, the review on page 58 is a worthwhile read.  Paul Vnuk Jr. was quite impressed by the Flux Bender and I'm sure Ronan will not be let down. The Flux Bender is a very serious piece of equipment.  Keep a lookout in the future for Ronan's review of the Flux Bender! 

Some may know from previous posts that I have been developing a new equalizer, called the Arque Equalizer.  This is a mono, passive EQ with a crazy ton of controls and it will be introduced to the market at a very low price point.  About 2 days ago I finally completed the first prototype after a great deal of real world use in the studio and many modifications to the design.  Next on the road to production is a second prototype, which looks more like what the final product will look like.  This next prototype is more for the front panel layout design than anything else.  I plan to have the product ready for release before the year is out.  

Simultaneously I've also been developing a new dual channel mic preamp.  I started with the 1401 preamp and began making changes to it.  It was originally intended to be Rev. B for the 1401, but its now so radically different I can't justify giving it the 1401 label.  The new preamp offers 2x as much gain as the 1401, while amazingly exhibiting a lower noise floor.  It has VU meters for both channels, front panel DI inputs (which sound incredible, BTW), and maintains the 1401 treble cut filter circuit and gain control.  The preamp currently has a slight deficiency in treble which I'm currently working to iron out.  After that's complete, the next phase is adding on phantom power, a low cut switch, and line input switches.  There's still a lot of work to do before its ready for production, but as with the Arque Equalizer, I'm aiming to have this product complete by years end.

The mighty Flux Bender goes on its second bender today.  This afternoon I'll be shipping off a Flux Bender to world renown Mix Engineer, Ronan Chris Murphy for his professional review of the EQ.  Keep an eye out on his youtube channel for that review in the coming months!