Guitar Amplifier Blueprinting

Guitar Amplifier Blueprinting
- Myles S. Rose -

"making guitarists sound better ... one amp at a time"

Guitar amplifier blueprinting? What the heck is that all about?

"Blueprinting" sets up and tunes an amplifier much in the same way as blueprinting the engine and suspension for a car. Using proprietary methods, we match the amplifier to the guitarist or bass player, for his particular playing style.

A guitar amplifier can be compared in some ways, to a production automobile. When it comes off the assembly line, it must meet basic requirements which are within a broad range of specifications. An amplifier can be "tuned", much in the same way that a race car is set up for a certain driver on a certain track ... suspension, engine tuning, etc.

We do not "hot rod" an amplifier, that is not the purpose here.   The amplifier is specifically set up for a particular guitar player's style and musical tastes.

The best amplifier manufacturers in the world, even if they had the time, cannot set up an amplifier in this manner. There is no direct contact between the player and the manufacturer in most cases. Sometimes you will hear of amp builders that do this, such as Dumble, but in most cases, this is not the norm.

Amplifiers are also shipped with various styles and brands of tubes. An amplifier using 6L6 style tubes, may be shipped with Sovtek, Svetlana, Tesla, or others. Each are very different in sound. A "6L6" amp may use 5881, 6L6B, 6L6C, KT-66, tubes also... all different.   During the process, we may swap tubes many times, working with the client to capture his "sound". Preamp tubes are especially critical in this area.

After the tube types are chosen, we move on to the second objective in this area; matching the output section of the amplifier.

Mis-matched tubes work against each other. Your notes will not "sing". Some notes will die a quick death of decay. Sustain is reduced dramatically and even absent at some frequencies. It is very important in a class A/B design, to have a close match in the output section. Any difference in waveform will be cancelled out in the NFB loop as used in Marshall and Fender style amplifiers.

Many times a player will have some notes "sing" and others sound lifeless. They usually explain to me, that it is "a dead spot in the neck" of their particular guitar. At this point, I have them try another guitar, if available, of the same type. About 90% of the time, they are surprised. The other guitar shows the same "dead spots" on the same notes. It is not the guitar ... it is the amp.    I also show them why this is happening on a scope with a signal generator. This is one of the reasons that the player must be present when we go through this process for the first time. This is not a procedure where you can drop off your amp and pick it up a few weeks later.

Another common source of these "dead spots", is an imbalanced 12AT7 or 12AX7 phase inverter or driver. Very few people match the two sides of a preamp triode. Some of the vendors selected to be shown in our tube vendor section can do this.

When it comes to preamp tubes, most vendors check that the tube "works". They will also sometimes check that it is not microphonic. That's usually the end of the story. It is not practical to expect that any tube seller would match the two sides of a dual triode as a general practice. This is time consuming, and requires specialized equipment. It involves going through a LOT of tubes and FINDING the pick of the batches. You cannot make matched triodes, you have to find them. This would easily double the cost of existing preamp tubes from suppliers. Some folks that sell tubes for high end audio and hi-fi applications will perform this matching at additional cost. The cost is money well spent. Less the 5% of preamp tubes are matched within the range we use for our phase inverters. Typically on a good day you will find 1 in 20 ... on an average day it can be 1 in 50.

A mismatched output section - If one puts the amp on the scope with a lower frequency input waveform, it is easy to see the non-linear waveform between the upper and lower sides of the sine wave. Even the most non-technically involved person can "SEE" the problem as well as hear the problem.   This test is done during the blueprinting process. THIS IS EXTREMELY CRITICAL FOR GUITARS USING DROPPED TUNINGS OR 7 STRING GUITARS WHICH TAX THE LOWER FREQUENCIES.

The first stage of gain, or the first preamp tube (usually called V1), is a very important and tube in your amplifier. It sets the initial gain, tonal qualties, and noise floor for the amplifier. If you follow the link in the tube reviews to the 12AX7 section, there is a technical paper on this subject, along with some tips and hints.

Bias has a great impact on the way an amplifier sounds, distorts, and compresses. Most amps are set to a specific value as the norm. If one sets bias in a conventional manner, the amp will generally have good tube life overall, and work fairly well.

Bias can be set to other values, which can change sound and feel. It will also change power, tube life, and where the amps output section starts to distort. Amps that have a grainy character as a design (such as Mesa Rectifiers), can also have their output section adjusted, even if you wish to maintain the fixed bias feature of these amps. Marshall amps with a crunch character can have this "moved" to lower or higher volume ranges in the amp. In a class A amplifier, there are other methods of producing the same results and even fixed bias amps such as these have tricks that can be done.

Once we know what you want, what you like, and we have made it happen ...all of this is recorded and documented. This makes it possible in the future to have your amp serviced if you cannot be available.

Once your amp has been blueprinted, you are one of our clients. If you are in the local area, you will be given a phone number to call for help, or be met at the studio or performing venue to fine tune or change things before a session or performance.

The service of blueprinting an amplifier generally takes about three hours, although in some cases, can take longer. This service is by referral only as we need to keep our client base at a level where we can provide emergency or critical service to existing clients. Email me if you would like additional information.

Tone Stacks, Response and why amplifiers "sound different"

Tube comparisons of some common types ... and why the "same tubes" are DIFFERENT
Tube reviews on some popular types and how they sound differently
Follow the three links below for detailed reviews and sound tests

A few folks and/or companies worth a special mention from my humble point of view - (scroll down for others too ... some have links to other parts of my website)

Amplifier blueprinting consists of the following operations:

1. Scope the amplifier for clean output before work is started. Record output in watts.

2. Scope the amplifier for maximum output in watts before work is started. Record output.

3. Measure B+ Voltage

4. Check Bias / current draw on existing output section. Record results.

5. Record percentage of current draw of output section. Record results.

6. Check match of side A and B, and microphonics of all tubes in preamp section of amplifier. Discuss
     various qualities of different preamp tubes and reach a target objective.

7. Check percentage of match between sides A and B of phase inverter.

8. Have Musician play amplifier and discuss qualities they would prefer if any.

9. Install new output tubes if desired and re-bias amplifier, or if non-adjustable bias or class A,
     replace the current tubes with tubes of a more optimum range.

10. Work with musician changing idle dissapation as to focus in on their particular needs, style,
       primary guitar, etc. Adjust as required.

11. Check phase inverter and match of output section using LF waveform to check for optimum
       phase balance. If necessary, replace phase inverter again.

12. Measure and record the final current draw.

13. Measure and record the final percent plate dissapation.

14. Scope the amplifier for clean output. Record output in watts.

15. Scope the amplifier for maximum output in watts. Record output.

If the musician wishes, he may supply his own tubes of his preference. I will test and classify these tubes as part of the process. I am not in the "tube selling" business, and there are perhaps better avenues for tube purchasing than using me as a tube salesman. I will be happy to advise in any case.

FREE GUITAR AMPLIFIER CLINIC and THD UNIVALVE SEMINAR

Saturday March 23rd 10am to 3pm

Westwood Music 1627 Westwood Blvd. Los Angeles CA 310-478-4251
(Just east of the 405 freeway on Westwood Blvd, north of Santa Monica and south of Wilshire on the west side of the street)

IF YOU WISH YOUR AMP TO BE CHECKED FOR PROPER OPERATION AND POWER OUTPUT, THERE WILL BE NO CHARGE FOR THIS SERVICE DURING THE CLINIC.

At the clinic you will learn the following about your amplifier:

1. Clean power in watts

2. Maximum power in watts

3. Noise floor - if your capacitors are good or starting to go bad, and this uncovers some other potential problems.

4. Transformer testing of the power transformer and rectifier section.

5. Output tubes checked for matching and wear.

6. Phase inverter checked for balance.

A card will be given with the results, which if you are thinking of selling your amp to another person, a store, or on E-Bay, will help attest that your amp is in good condition.

This is for working amplifiers only. This is not a repair service. If your amplifier has had problems, please let them know on your appointment, as the maximum output tests cannot be done. This will put too much of a strain on old or mis-adjusted amplifiers.

Last Update 27 MAR 02

Some of my thinking can be found on two music forums. One forum is at www.musicplayer.com (Guitar Playler Magazine) in the Forums / Guitar area. The other forum is at www.harmony-central.com in the amps area of the discussion forums. In either forum, just seach for "Myles" to find subjects such as feeling on the latest modeling amps, and the latest reviews on tubes such as the 6L6 and EL-34 which were completed recently. In the case of Guitar Player's forum, there is also usually a topic called something like "feel free to ask Myles", as I am the forum moderator, where you can ask for help.

Myles Saunders Rose has worked in various development, design, and support roles and projects including development work for Roland, Yamaha, and was Apple Computer's music consultant for the Vivarium project in the 1980's. He was around playing on what is called vintage today.... when it was NEW. He has played guitar since the age of eight, and hates to admit that he played the accordion from the age of five ... but then again, there were only seven channels on the television, and one was dominated my Lawrence Welk back in those days!

Phone contact numbers available on request. Myles may be contacted via email at: myles111@hotmail.com

Free Amplifier Clinic and THD Univalve seminar Saturday March 23rd - see details a little further down.

If you have any kids, if its not too much trouble to ask, please have them follow this link to his website. He wants some hits from more than just his own family :) he is ten years old.

His website is at www.geocities.com/jackrose111

Endorsed by us ... and used by us ...Vacuum Tube Suppliers and vendors on the internet

Eurotubes - an excellent source for JJ / Tesla tubes at possibly the best prices on the net. The owner is also a great fellow. Look at their high end audio amps too! By the way, as far as matching goes, Bob typically supplies tubes within 1 mA !! He understands the aspects of a matched output section. He can also supply matched preamp tubes for phase inverter use.

KCA NOS tubes - lots of new old stock and premier tubes. They can also supply matched phase inverters. These folks are loved by a lot of folks out there. These are the other MUST CHECK for any consideration of NOS tubes. You cannot go wrong with either KCA or Tube World when it comes to NOS.

Sovtek - also known as New Sensor. They import Sovtek tubes and many other manufacturers tubes. They also carry a side range of other products including a wide product line of their own amps and effects from Electro Harmonix.

Magic Parts - supplier of Ruby tubes and other amp parts, speakers, transformers, etc. These folks have a lot of great parts and restoration hardware for vintage amps. They are quick to ship and have good prices.

Torres Engineering - nice selection of many manufacturers tubes, mods for amps, amp parts, transformers, and MORE. They have their own line of amps also. They are great folks, and if you like amp mods, their's are some of the best. These folks also have some great info that is very helpful on their website.

Groove Tubes - There is really a bit more to these folks that I can fit into this little section, so follow the link to another section of this website. From there you will see a few comments and a link directly to Groove Tube's website.

Be sure to check our test progress on the upcoming GT 6L6GE "new" USA tube in the 6L6 reviews

Tube World - an internet supplier of most tube brands. They offer good pricing and a wide selection. Vast selection of NOS tubes. Also a source for very closely matched tubes. These folks are a MUST CHECK for any consideration of NOS tubes. If these folks don't have it, and KCA does not have it, you're in serious trouble!

Watford Valves - in the U.K. but they ship anywhere. A very extensive inventory. Their testing methods are extremely rigourous. They can supply matched preamp tubes for phase inverter use. These folks have extremely high QA, and as close as their tubes are matched, their Harma line is even nicer. I guess it depends which side of the "pond" you are on to pick between some of these folks.

In regard to tube matching, the vendors below all do a great job. I miss a lot out there in the world, so if you have the names of any folks I have omitted, please let me know. To those not listed here that may deserve to be, I apologize in advance. For now, its these folks that always come through with results that far surpass many other vendors we have tried. We continue to try the other vendors a few times per year to see if there are more we can add to out list.

Groove Tubes, Eurotubes and Watford Valves generally match within differences that at times are so close that is hard to measure. Groove Tubes uses a different method than strict current matching, so their tubes are generally tested on a vacuum tube curve tracer, and we find the traces are extremely close.

The folks at KCA and Tube World, both NOS vendors, do a great job at matching and grading.   They are not in the same tybe of business as the folks above. They primarily deal with NOS offerings. With NOS tube, you'd expect to know the condition of the tubes as part of the price. They both do this very well.

In some cases with any of these folks matching may carry an additional charge. For matching the two sides of a preamp tube, expect to pay an additional charge as a general rule.

In a recent tests on the Electro Harmonix EL-34EH, we had some matching issues surface from two of the vendors where we procure some of our test tubes, I will quote back from that part of the test report:

In our matching tests, its was once again confirmed that most folks use the conventional current matching method, as the tubes were close or almost perfect in this aspect, but fell a little short when looking at factors such as transconductance, rise time, and linearity.   Matching for current draw at a static voltage and bias is a bit different than what the tubes will be subjected to in a guitar or bass application.

While matching in this fashion yields fine results in most guitar amplifiers, it is one of the factors that makes some amps sound terrific of a specific model of amp, but one amp just stand out and sing in the same group. This was one of the thoughts which sparked the idea of "guitar amplifier blueprinting".

One cannot expect tube vendors to match tubes, one at a time, for 15+ minutes per tube on scopes. The cost of tubes would be out of the reach of most of us. In a Hi-Fi application where tubes last years, this might be fine, but in the torture of a guitar amp where tubes are changed more often, this is not as practical.

While on this subject, this is one of the reasons that if you have something like a bias probe or bias king, you may find some tubes closely matched in your amp from some folks, and not as close from others. If a tube is off by more than 15%, the tube may have had some shipping damage. Just a simple drop in the UPS or Fedex truck can move one of the little grid wraps just a few ten thousandths of an inch, and there goes the matching. Tubes are fragile when cool, and very fragile when hot.

Keep in mind that some folks match and measure a number of parameters such as current draw, transconductance, grid leakage, gassification, and other factors. If you look at these tubes at a static voltage on the plates with a static bias voltage, they might appear to be a few milliamps out of "match" from strictly a current draw standpoint. When you put these same tubes on more sophisticated test equipment, in dynamic conditions, they tubes match up more closely than those tested using static methods in almost every case.   If you want more information on this subject, the old RCA and GE tube manuals have entire sections on "testing". This is the reason that tubes from Groove Tubes appear at times to have a different "match" than a tube tested on static load equipment, yet on a vacuum tube curve tracer, they will display a closer match than tubes with closer current draw numbers.   I demonstrate this at least a few times per week.

If you follow the Groove Tubes link below, there is a response of mine in regard to another tube vendor that makes specific comments in this area where I disagree.   This particular vendor also makes other statements which are misleading to the consumer.

As far as Groove Tubes on the road ... when the conditions are rough and the living is worse, their measurment, matching or packaging translates to about 20%-30% longer life in touring conditions for my clients. To me, this justifies any increase in cost with GT products.   In amplifiers that average only three nights on a set of output tubes in a concert venue, Groove Tubes will go five nights for my clients.

I will list no vendor here which I have not personally used or tested their offerings. All vendors here go through at least three samplings per year to verify their QA or QC.

Their website is partially ready, and they have an extensive line of vintage guitars AND amplifiers! They have over $20,000 of NOS tubes on hand, and the place very comfortable and professional. Their vintage amp stock in very impressive and all are in great condition.

They can be called at 818-789-8884.

Their location is at 5244 Van Nuys Blvd. in Sherman Oaks .
(They are just north of Magnolia, bear to the right when the street curves)

Around even before I was born, and great folks. Follow this for my comments about them and from there, follow the link to their own website. Be sure to click the above link as they are currently selling some of Joe Walsh's guitars and amps. One of the stores in So Cal that has most of the finest amps and guitars in stock all the time available to play.

Amazing custom work, super repairs and modifications, a true master craftsman with great people skills an impressive client list of happy folks, charges that won't have you gasp for breath, and ... he's a great player!

This is a link directly to their Hollywood store site. John and Jimbo are two of the greatest guys in the business. John's latest designs in front end effects have to be seen and heard!

THD and Andy Marshall, are the folks behind the "Hotplate", "Yellow Jackets", and the most versitile sounding amps I have ever hear ... the Univalve and Bivalve (the hits of the 2001 AND 2002 NAMM show. Follow the link above for a few words about THD, and a link to their website.

If you look at Harmony-Central, a number of folks have had a lot of nice things to say about their products.

On my website is a chart for owners of Univalves, which may be of interest.

Paul Rivera has been in the amp business since the 60s. He has produced designs for Fender, Pignose, Yamaha, and many other companies, as well as his own line of amplifiers.

He has a wide line of amps, all just magic. He is about the only one that has his amps voiced both British and American. His construction and attention to detail and design are second to none.

Follow the link above for a bit more, and from there, follow the link to the Rivera website.

If you want to learn more about tubes than even the vast majority of the people who sell them, and are up to a very technical explanation, just click on the link here ... but BEWARE ... once you start, there is no turning back! If you dare - click here!

Before you argue the pros and cons of "tubes vs. solid state ... or modeling amps vs. vintage amps" ... I agree modeling amps are good recording and composing tools, and there are some fantastic SS amps which are just the ticket for some forms of Jazz, Rhythm, and Acoustic guitars. BUT ... if you are looking for the tone and sound of actual tubes, then you may want to look at this IEEE article which talks about tube vs solid state specifics, tube history in the music business, transistors, and modeling's future. You can get directly to this white paper by clicking here

Steve Carr designs and manufactures classic circuits using Class A designs for the most part, but without the focus of using the EL-84 as many Class A designers. His "Rambler" is a Class A design using 6L6's, and his "Hammerhead" is a very high gain EL-34 based amplifier. He also produces a unique class A/B amplifier. Carr amps are hand built and use the finest components. His "Rambler" is one of the finest "Blues" amplifiers I have heard.

Norm's ... if you cannot find your dream vintage guitar here, I'd be surprised. Norm's is one of the top vintage guitar shops in the world. He has personally sold me a number of instruments over the last decades. They are also an authorized dealer for many new lines. While Norm does not focus on amps, it seems that each time I visit his store, there are always dozens of surprises waiting. They do sell new Fender amplifiers also. Their prices are excellent, but their expertise, selection, and interaction with folks is what sets them apart from many other stores. I personally recommend them very highly.

If you found your way here via the URL printed on my old business cards .... www.geocities.com/myles111us ... the new URL for this site is www.guitaramplifierblueprinting.com

Friends and photos of their amps, guitars, etc.

Sound clips maybe too

Follow this link for photos of folks I have met on the net, friends, etc. If you have any pictures you'd like posted here, please feel free to send them.

If you have any soundclips you'd like posted, please send the link to the soundclip with a bit about the clip ... what guitar, amp, effects, etc. I'd rather have the link than the clip itself, as they take up disk space, and the photos might too too much possibly as this gets built.

ITEMS FOR SALE BY FORUM FRIENDS, CLIENTS, AND OTHER FOLKS.

Folks with this color background are my personal favorite TUBE suppliers. In the case of Torres, I like them for everything, but the others are mostly TUBE folks, hence the color difference.

Antique Electronic Supply The folks at AES supplied me with the following writeup on their products and services: Antique Electronic Supply offers the most diverse line of products for all types of tube gear including vacuum tubes, transformers, speakers, capacitors, parts, supplies and literature. We have the largest inventory of NOS tubes in the U.S. and also offer a large variety of current production tubes. We offer Jensen and Celestion speakers, Hammond and One Electron transformers, Original Fender, Gibson, Ampeg and Dunlop replacement parts, Accutronics reverb tanks, Pro Co and Maxon effects pedals, Caig chemicals, Weller and Xcelite tools, and an extensive line of books. Contact us for your free catalog or browse the catalog/shopping cart on-line.

On a personal note, these folks have a lot of great books if you are interested in tube equipment, and sell speakers such as Jensen and others at nice prices. They also always have the output transformers I use most often in stock all the time.

Past articles, technical papers, and some forum responses can be seen by clicking here

What makes a Fender sound differently than a Marshall? What are "tone stacks"? Is a 100 watt amp two times as loud as a 50 watt amp? Click here to find out a little more.

TUBE MATCHING - A FEW WORDS

For reviews and reports on 12AX7 preamp tubes, click here

For reviews and test reports on 6V6 6L6 5881 KT-66 click here

For reviews and test reports on EL-34 and EL-84 click here

Technical paper on Rectifiers - Solid State versus tube. Changing even within tube rectifiers can make your amp feel different, have more or less power, different compression, etc. click here

Tube news ...

Marshall trick to help when pedals are used. This was added to the preamp tube article in the 12AX7 section.

JJ factory expects to release new GZ34 / 5AR4 vacuum tube rectifier in about May of 2002.

JJ factory will start development of a new 6V6 tube. It will be about a year in development I believe. This may be a nice choice other than NOS.

The Groove Tubes USA made GT 6L6GE is testing out very well. It is still on target with first deliveries expected this early summer.

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There are also some preamp tube hints here to make your amp sound and feel differentlyl