x-ray tubes

We have all heard the stories of mercury tubes and radiation and here is another take on the subject.  There is a guy named "kenpeter" over on DIYaudio who started a very cool thread using X-rays to look at grid alignment of tubes.  Since most of the talk centered around multi-grid output tubes, I just sit back and enjoy the pictures.  (both pictures borrowed from the thread and belong to kenpeter)

 

So I promised I wouldn't....

put up any links to eBay stuff... but this is different. Not only is this my absolute favorite horn from an industrial art point of view, but it is also one that I have promised to build...


It was incredible just to wake up to this beauty in my Inbox... what I want is to wake up to Ella singing through this baby in my bedroom every morning. Who wants an alarm clock that buzzes when you can have one that sweetly whispers into your ears?

I wish he would take Paypal... then I would contact my new Nigerian prince friend and see if he would transfer that money into my Paypal account...

Ghost bunny has respect.

 

  Chews on a Vice Grip instead of Morgan's book.

GOOD BUNNY

a fellow Western Electric junkie...

just couldn't stand it.. and has volunteered to be the lab rat for the WE version of the phono stage...


The input tube will likely be this WE 436A in place of the Amperex 7788 on the "standard" phono. The output tube is the WE 101... a transcendental directly heated triode... and I do love engraved bases - the proper way to label a tube...


although, looking at the WE yellow ink in detail reveals some super cool script... man, I guess everything WE did was well thought out....

103 Cocktails.

the 103 iron is still in the fire and the project seems like it will make it to fruition.  Here are some updated pictures on the innards.

Next up is where we plan on taking this.  Granted it is only a cocktail napkin sketch but ya gotta start somewhere. 

This brings me to an interesting realization that sometimes it it much easier and more rewarding to get your hands dirty and do a sketch to see where things go rather than a Cad drawing to get it done.

Whoever heard of the *304TH*?.

Nope, not the 304th airborne division from WWII.. not the 304th infantry... but not the 304TL either...

The big amp is back out. Nope, my back isn't out.. yet.. the near 500 pounds (without chassis) of the big single ended breadboard is heating the shop again. I want to run the amp full range, so the multi-amped horns are down. I have an old pair of paper and alnico multi-ways that are low 90's efficiency- just perfect for making the amp put out some power. I have been listening happily, but I just thought the bass wasn't what I remembered.



In comes two 304TH Eimacs. Knowing that I had plenty of inductance in my output transformers, I decided to throw them in... one cathode resistor swap, and done... The bass was instantly fuller and richer. Time for a lesson. Skip down to dave's dog post if you don't want to listen to my technical rant on why tube bass really isn't sloppy....

When I swapped out the 304tl for the 304th, I upped the output impedance of the amplifier. The amplifier and speaker form a system. There is an optimal value of output impedance for critical damping. A higher output impedance than required for critical results in overly full, slow, sloppy bass - underdamped. A lower output impedance than required for critical results in overdamped speakers - fast, controlled, but thin and unnatural. ...and here is my issue - speakers designed for tube amps should be used with tube amps. However, when solid state came along, output impedance dropped dramatically. Speaker designers had no choice but to accommodate the new amplifiers as they were 99% of the market. When you use a tube amplifier with a high output impedance on a speaker designed for low output impedance transistors, of course it has "flabby" bass... this is no reflection on the amplifier, but a reflection on the mating!



so back to me... I am happy that I apparently found the proper value... basslines don't strut without it... and I got to try a new tube... :^)

Ebony and Ivory

I get it... the whole perfect harmony thing but why must they harmonize on my couch? 

It isn't a pinup girl...

but I do have some Friday curves for you to ogle...

First, just a picture of the remote Passive Aggressive I need to box up and ship out. It was done in a more traditional form factor to fit a rack. This design also leaves plenty of room for future expansion into line level crossover parts.. so it is sneaky evil...



Next is the real excitement. I flipped when I saw these pictures of the 75tl close up. It makes me want to learn a little more about proper photography to document some of these beauties. Sneak peak here:



The real deal here: Eimac 75tl Amplifier

Super thanks and Copyrights to Paul Jeremias Photography, 2009.

I Am Wireman.....

Got the original field coils back from Johnny who decided to take them from high voltage to low voltage for safety reasons.  This means I needed to crack them open and remove the 22,500 turns of #30 wire from each.   While unwinding them a new beast came to life and in case any of you have ever wondered what 6.5 miles of wire looks like I introduce you to Wire-Man.

 

The two things on my hands are the pole pieces of the motor structure and only yesterday, all of this wire was neatly held in place.   I originally wanted to introduce you to Iron-dog but I quickly found that was a really really bad idea.

For reference jeffrey was kind enough to offer a similar treatment with the size of wire they will be rewound with for LV.  I'll let him tell the rest of that story at another time.

Gotta get it back up and running...

My entire front end is on the west coast. They are doing well, but I miss 'em. Both phono and line are traveling about. I was ok with this as I needed to work on my whole music server digital rig, BUT.. BUT.. I hit a snag. My ten year old (sweet sounding) dac doesn't like driving the autoformer volume control directly. Its output impedance is way too high. I tried the op amp analog outputs on my Rega Planet that has been my trusty transport - I kinda gagged a little bit - Awful. So I cobbled together something that turned out to be a real beauty.



It is just a line stage. However, it has a very high input impedance and will happily drive the autoformers. The sound is just as I remembered. I love those tennis balls. They have some nice gapped nickel on their plates, of course. Oh, and mercury... Tomorrow I will try it as a strain gauge supply... WE tennis ball strain gauge supply... pure evil... three tubes needle to speakers.. and all directly heated triodes..

What you find in the yard

I had a freakish goodwill experience the other day. I have been looking for a number of titles on ebay and constantly getting out-sniped.  When I went into my local thrift to look, from 30 feet away I saw this. 

Stupidly thinking I was in a movie, I sprinted to avoid all of the other fanatics and dove on it first.  It was clean enough and I was dreaming about what must be below.  Could I find all of the music of my young adulthood?  Sadly that wasn't the case and it cost me $8 for my prize and 6  other things that need to go into the "needed to be cleaned" pile which as the lyrics say  "push it along".

 

Music Maker of the Month - Mats Gunnars...

I think it is time to introduce a new repeating post to the Blog - MMM - Music Maker of the Month. The goal is not to show who had the best, we have already moved well past that. The goal is to present systems that meet that magic threshold of getting out of the way. With these systems, you hear music, not the system. Do they have issues? Sure. Do they make music? Absolutely.



So enter Mats. Mats is one of my heroes. The man has two walls of vinyl. And a seriously thick section of those orange and black 1960's Impulse artists that I like. Those Impulse pressings are the perfect example of not being the ultimate recordings, but very full of music. Mats has two turntables up and running... a five way system... four of the five are horns... he is quad amplifying with line level crossovers.... Mats even has true 20Hz horn bass with an old tapped horn of mine from years back... keep in mind that all of this is in a city apartment!




Mats is also my healer. How he knows what he knows, I hope to one day understand. He has somehow moved past what most of us think (worry?) about on a daily basis and moved to sensing the pulse of the universe. From more than 500 miles away, the man can correct my ailments from inflections in my voice. Fix my diet even though he has no idea what I am actually eating. and then there is this:



He cannot know that for years now my favorite reply when Lisa gets onto me about not sleeping enough is "I'll get plenty of sleep when I am dead."... And yet this is what shows up in my inbox from Mats. I often tell people I subsist on solder and coffee... and speaking of, on this Monday morning that the heat in Bessie (my old volvo wagon) decided not to work, I am ending this post and headed to the kitchen for second coffee... then to solder...

Mu-Wood

Been working on various ways to shield SUT's over the past few years and I must say mumetal is a pain to work with.  It cuts nicely with a paper cutter but getting holes in for RCA's and such is no small task.  I went to the local hobby store and bought some 1/32" birch with the idea that adding some support to either side would allow it to be drilled easily.  As an added plus the 1/32" spacing gives a nested effect.

The mumetal I had already has adhesice on one side and some simple spray glue kept everything together.  It still has some wiggle but i'm sure all that is needed is some permanent glue.  The most interesting thing about it is the result of the "rap" test.  Unlike normal plywood which is quite lively, this stuff is surprisingly dead. 

dave

burning down the house

My old dual lambda PS has seen better days.  I was testing some 103 concepts and the burn from the finger test on the coil made me mad... no it made me angry!  While watching channel 103 heat up, I figured channel 2 would be fun for some play so onto the story.


Meet resistor 1

 

Here is what the AB man would say under stress.

and then open circuit.

dave

Take me to your leader....

I just can't stop staring at this one... so I thought I would share.

Marti Radio, R108, Martian Beauty

103 puzzle

props to sean for the subject.

dave

cats and bags.

It is really odd how some things happen.  I was debating if I should give the update of what is new and I even went as far as trying to take a picture.   Since Marvin tried to put his better half into the picture I just felt the natural progression is to go with it.  (pay no attention to the duct tape just out of frame)

Aside from that gray furry tail hot glued in place, this is another Field coil project that JJ and I are working on. 

JJ's mention of the switch to the aa strain gauge has me inspired to let another cat out of the bag.  I will be ordering up parts for a simple pentode riaa that we have been dreaming about and it is time I revisit the traditional riaa camp to keep myself grounded. 

Working metal....

I am floored. My blacksmith came through town yesterday. The passion was evident in every aspect of his work. We have just been talking via email about the stands for the big horns (Exhilaration III - in the works for years now, but finally close). I had no idea of his depth of work. I knew he held the same ideals about quality and craftsmanship that I did, but I am just stunned at his attention to detail.



Check out the lacquer on that half inch thick, twenty pound chunk of bronze... multiple coats... wiped back... worked the edges to show the bronze.. and the engraving is simply over the top.... Then he said they were working on the CNC, so he just experimented by making a few badges. Acid etching.. engraving... heavy... These are definitely where I am headed. We both spent hours and hours studying the 1920's radios I have around here. The attention and thought are in every joint, every fastener, every finish. Look for some new chassis from me soon, half rack width, inspired, as always, by the past. Likely the DHT strain gauge supply will be first.



and now to the horn stands.... I will upload some profiles and 3-d drawings soon, but for now examine some of the detail work on this horn support. I totally agree with his assessment that we don't want to hold up those mahogany midrange horns directly with metal. Something more organic is required. I have used rope in the past, but this leather strap is totally the way to go. It is extremely thick, cut to the horn angle, and sewn together in a nice, heavy, double layer construction. It reminds me of well-made saddles - strong, tough, and designed to task. It is then attached with brass rivets to a pivoting steel connector, patina''d, of course. The stand itself will be this triple steel construction. Each steel outer edge is brass riveted to the inner truss-work. Heavy, solid, simple. I can't wait!

on the theme of controversial....

so here is another one out of the closet...

I am the cover model for the triode mafia. All triodes, all the time!... Use a pentode, go to jail!... and then it happened... on one of the many long conversations dave and I have while working late night, the conversation turned to why anyone would ever use a pentode. We inadvertently made a list not only of what triodes do better, but also a list of what pentodes do better than triodes. The two that are very obvious and very big are that pentodes are several orders of magnitude easier to drive, and that they have lower distortion driving low impedance. Guess what? This is exactly what we need to drive an LCR RIAA circuit.

I have now compared in two different circuits - IT coupled (yes, IT coupled pentodes!) to an S&B 10k LCR and also nickel plate choke loaded and direct coupled to a teflon and nickel Intact Audio LCR. In both cases, it was not even a contest. I am a believer! Much more music! When you find yourself enthralled with the ballads of Art Pepper as much as the hard cuts, you know you have found it. Critical comparisons stopped being critical thirty seconds into each band.



So add phono to the list of things that I do not think will be revisited anytime soon. DHT linestages with nickel 1:1's and nickel autoformers - check! stacked supply direct coupled amplifiers - check! pentode phono front end - gasp - check!

oh.. and no wondering where the chassis style for this one originated.... It is funny though, as I originally built this phono years ago, long before I owned a WE7A. I guess I have been pulled this direction for years. Now to work out the Western Electric pentode input and tennis ball triode output version.

Hey Babe....

One of the more controversial things I do is wind Nickel Chokes for PS usage.  These 80% nickel units are going to a customer in Canada and are to be used in the L2 and L3 position of some mono amps he is building.  I know many of have heard the light and embraced nickel for PS usage and while we don't exactly know all of the "Why's" Our ears tell us we are not making this up.

 

These things are small, the size of a Dyanco ST-70 choke and I first caught wind of the nickel PS choke thing paging through Sound Practices and seeing the ads for April Audio selling the Nature Sound permalloy PS chokes.  For those of you not familiar with Sound Practices, Spend the best $29 you ever will and learn about Papa Joe.  Back to the topic at hand.... I was firmly in the PS choke is a PS choke camp and laughed at the concept of $500 a pair for PS chokes.  I had the great fortune to meet Uchida-san of April audio before he passed away and the most memorable moment from the visit was him cradling a Permalloy PS choke in his hands and passionately stating "Very beautiful sound".

A number of years later, Steve Berger who took over Aprilsound  paid me a visit with a pair of the Nature Sound chokes and I skeptically clipped them in place of some potted milspec Low DCR chokes.  My life has never been the same.  Like my first experience with mercury, I was hooked and needed more nickel in my system. 

 

That was over a decade ago and the stash has been growing ever since.  The good news is my habit doesn't take up anywhere near the space that Jeffrey's does.

dave