Ten years of the L.A. Ampshow

What I learned from the failure of a single tube

This morning I woke up thinking about my friend Dan Boul.  OK.  That may be a bit misleading.  I love Dan like a brother but ....   

I had a huge dinner which may have contributed to weird dreams.  Could that have contributed?  My Facebook friends are aware of the dinner I had last night as a side note.

The thought was about the day The Whiskey died a few weeks ago.  

Probably got your attention by now?  Possible man crush?  Amp failure?  Click on "Read more" below to continue.

KT-150 Tung Sol vacuum tube

Test results and observations on this new tube offering.

Tube Depot ( great folks) says that a pair will produce 300 watts yet the max plate dissipation is spec'd at 70 watts.  I don't understand that 300 watt figure.  A KT88SV as a side note is 50 watts and a regular KT88 is 42 or so watts.  They run $90 per tube.  

I will be looking at these asking myself ... is there a reason?  How do they sound when driven to distortion?  (A KT88 distorts in a lovely way but a 6550 distorts in a quick and raspy way that is not too pleasant).  Do they last at voltages on the spec sheet?  Most tubes today do not.  How long will they keep going at full rated voltages?  (My standard series of life tests.)  What do their traces REALLY look like?  Design spec drawings are often not close to being accurate.

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Current Production 12AX7 Tubes

Click on this image for a larger image

I have been promising a current test of some of the current production 12AX7 / ECC83 offerings and have just completed my testing.

Gain and Transconductance. Some folks confuse these two things. Maybe this will help explain:

Gain is the factor by which an amplifier multiplies a signal. It is the product of the output voltage at the plate divided by the input voltage at the control grid. Gain is a unit-less factor since both measured signals are voltages. (voltage)

Transconductance is a measurement of the ability of a tube to transmit current. It is the product of the output current in amps divided by the input voltage at the control grid. Transconductance is significant in that it shows us the difference in current capability that is generated by variations in plate impedance between tubes. (Current)

When I test tubes I also measure standing plate emissions current for preamp tubes that will be used in the phase inverter position. Plate current is one factor that many tube testers do not measure.

150 tubes were tested. 15 of each type.  The above lines on each tube are the average of that particular tube.

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"Genalex" Gold Lion 12AX7 / ECC83

Some of you have been asking if I could make some of my tube testing available again.  This is the first report that I have put out to the public for a while.  I will continue to put reports on this blog.

To see the full report just click on "read more" below

The Day The Music Died?

Any image in this piece may be clicked on for a larger image.

It had been a while since I spent the day in Hollywood visiting some of my friends and some of the music stores.  My thought many times during the day was a lyric by Don McLean in the song American Pie ... the day the music died.

Back in the mid 70s through the early 80s we were treated to Disco.  It took time (way too long from my personal point of view) for Disco to die.  

I talk about the state of vacuum tubes and how there has been a steady decline over the last decades.  Today there are more "types" than ever and the offerings are worse than they have ever been.  As sad as I have been over the state of vacuum tubes the state of guitar amplifiers seems even worse.

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A bit of amp blueprinting from the past

I was going through some records on some customers amps from the past.  I came across one blueprinting session that was a little different than most as these were preamps which contained eight tubes.  There were also multiple units that were very different as the model had changed in revision levels over it's production life. 

I thought that going over some of the data would shed a little light on some of the process of blueprinting and some of the ways that tubes are very inconsistent.

Bogner Fish Preamp - 8 12AX7 tubes.

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3-13-12 - A day at 65 Amps

It has been a while since I wandered around the shop over at www.65amps.com and took some snapshots. 

Today seemed like as good of a day as any. Activity is on the increase with the Producer, the Empire and the Ventura amps in production added to the continued requests for amps like Lil' Elvis, Tupelo and Soho. 

These shots are raw format. There is no cropping here. No photoshop, color enhancement or alteration of any sort. I just walked around the shop and took about 110 snapshots in less than 15 minutes. If you have issues with my composition that is part of my snapshot style. If I wanted terrific shots I would call in one of my great photographer friends :)

If you look around the shop you will find Lil' Elvis hiding all over the place. 

Vacuum Tubes Today and NOS

Vacuum tubes continue to be used today in high end audiophile equipment in the recording industry, home and in music instrument amplification.  Guitar amplification utilizes the highest percentage of current vacuum tube production.

I have been publishing test report results on the subject of vacuum tubes since 2002.  The news is not good news.  The trend is not a good trend.

If you click on the above image it will enlarge to a more readable size.  I will refer to this image later in this piece.

For more just click on "read more" below

Tube Test - 12AX7 Tung Sol Reissue

This was the last run in January 2012 of the Tung Sol Reissue that I performed at the request of Dan Boul over at www.65amps.com

This is the current "Tung Sol" tube from New Sensor.  This is the tube which was tested

To see the full story click on "read more" below

Tube Test - JJ ECC803S

Test results of the JJ ECC803S Long Plate vacuum tube.

Today I spent a bit of time working with Mike Franceschini over at 65 Amps.  Mike wanted a bit of data on some of the tubes used in the new Producer from the folks at 65 Amps.

In one of the positions of the design they use a JJ 803S.  There were some anomalies that were thought to be tube related.  I was asked to investigate.

Click on "read more" for the full report.

A few hours at 65 Amps

These photos are the raw files.  No cropping, enhancing, editing etc.  Typically I at least tend to look over the shots and perhaps crop a bit or color correct.  Not so this time as I used a small camera rather than my cellphone camera.

More below...

The GC1 Guitar - great guitar

Today I am taking a few moments to post the link to a fellow that crafts a wonderful guitar.

There are a lot of terrific guitar builders out there and hopefully I will post links to some of them in my future blog posts from time to time.

The GC1 Guitar - Home

As a point of interest, the guitar above belongs to Steve Kirk ( http://stevekirkpop.com/ )  Steve Kirk is the most listened to guitar player in the history of amplified guitar music.  Am I crazy for making this statement?  Seems that I am on track, there were even a few news stories on this fact.  Steve Kirk wrote and performed the theme to FarmVille, a game played on facebook by millions of people each day.  The theme runs in the background of the game as it is played. 



Vacuum tube post from the past - where they are made

I initially posted this as a note on Facebook in June of 2010.

There has been a bit of discussion on the post so I thought that some folks that subscribe to this blog might find this of interest.

Older photo which shows GT "made in USA" silkscreen. Aspen was called out on this with legal action so the silkscreen was changed to eliminate this statement.

Today I received an email from my friend Rob Hull over at TubeDepot. Rob is is their technical director. He is a great fellow and has produced a lot of terrific videos about amp service and videos on many technical subjects.

 

Below is Rob's letter and my reply. Feel free to write Rob with tech questions as he is a great resource.

EL84 discussion on the Dr. Z Forum

Over on the Dr. Z amp forum I have a column in their Ask the Experts area.  Yesterday I was in one of the other areas and came across a post on the Doc's new Z Wreck amp.  

For a year or more this amp was not a product offered in the Z lineup.  The amp was only in the hands of Brad Paisley.  The amp is now available to all. 

As a side note, there is info on the amp at http://www.drzamps.com/amp/z_wreck/ 

One of the owners of one of these amps had posted some comments on the EL84 output tubes he uses.  I jumped into the thread.

Feel Free to Ask Myles - technical amplifier talk

My pants too short and 8 out of 10 amps I tested on this day failed :-)

Helping guitarists sound better, one amp at a time.  Some questions from two columns I write may be posted as blog entries from time to time. 

Some questions have been addressed in a few fun videos.  I will also post links from time to time with updates on additional questions or commentary.  If you have a specific question feel free to post it in this post as a comment, post it on one of the forums or send to my email listed in my profile here.

Guitar Player Magazine:  Music Player Forum; Feel free to ask Myles - http://bit.ly/iZGvIu 

Z-Talk Forum in the Ask the experts area, Ask Myles or Chad - http://bit.ly/lJakRD  I address amp issues. Chad Weaver (Terry Clark, Brad Paisley, Taylor Swift) addresses performing tech issues (guitars and other instruments, pickups, stage mics, wireless, life on the road etc.)

My GAB website covers a subject or two -
http://www.guitaramplifierblueprinting.com/ and there are many resources on the right side of this blog that may be of interest or help as well.  I am updating this blog site more often than my GAB website as a side note.

Click on "read more" to continue to read this particular post.

Vacuum Tube Series - 5751 Tung Sol, RCA, GE

Vacuum Tube Series

I updated this to add the link to the RCA version as a second data sheet set.

This will be a continuing series on vacuum tubes and amplifiers.



Some folks do not realize that the 5751 vacuum tube produced today is little more than a 12AX7 that did not make the grade as a 12AX7. .....

Vacuum Tube Information for Tube Fans

Just a bit of info for tubes fans - over on my GAB website you can download part II of my Tube Primer. It is a PDF file and about 100 pages that has a bit of info on vacuum tubes. Feel free to share.

http://www.guitaramplifierblueprinting.com/Tubeprimerandselection320-2.pdf

Myles Rose is the founder of Guitar Amplifier Blueprinting which provides support services and training for touring bands and individuals as well as blueprinting services.   I offer consulting services to various amplifier designers and manufacturers.  The link www.guitaramplifierblueprinting.com has links to music industry forums which I moderate and direct email contact information.  My shop is located in the complex at www.65amps.com.  If you wish a tour of 65 Amps please feel free to contact me directly.  When I am not doing something related to music I do what I can to support the homeless of Los Angeles either directly on the streets at night or through my good friends at Union Rescue Mission.

www.urm.org

The most critical, least expensive, most overlooked tubes in your amp.

Loni Specter on the left of http://www.ampshow.com/

I picked the photo above of myself and Loni as the 6th annual Los Angeles Ampshow is coming almost here, October 2,3 of 2010 in Van Nuys California.  I will be there as always and will once again be the moderator on the Tone Wizzards panel.

With the ampshow on the horizon I felt that posting something from another side of my life might be a nice change.

Preamp Tubes - The most critical, least expensive, most overlooked tubes in your amp.

The tonal signature of "your sound" and interchangeable without adjustment or the need of an amp tech.....