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When designing a tube amp, preamp, CD player...anything tube....


Coytee

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I think I understand that the circuit itself is going to be important.

 

So, you are sitting down with a blank piece of paper.  You are going to design a tube "something" (I don't think it matters what for my question)

 

When the circuit is designed, are you designing it specifically for a certain brand of tube that might be NOS or just a certain TYPE of tube and you don't care what brand?

 

Somewhere along the line, people start to roll tubes.

 

Does the designer want a specific sound so he chooses a specific tube?  How does he know what the tube will sound like given that his circuit might be excellent....or a dud?

 

Do you redesign the dud circuit around the same tube until you get the sound you are after or, do you change the tube to see how that combo might sound?

 

I admit, I don't know enough technical stuff to even ask the questions intelligently....

 

I guess at the end user stage, we have the tube "item".  We know that it is supposed to use "X" tube in it and as an end user, we might select several to see what flavor we might get.

 

Does the designer go through the same process for the end flavor when he's drawing out the circuit? or is it more a matter of he can draw a good circuit and it will sound good with most tubes so us end users are simply apply some salt & pepper depending on which end tube we use?

 

 

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Not an amp designer but from what I've read they pick the design and tube type to accomplish a certain goal and meet certain specs then they voice the amp with small part changes and adjustments with a specific tube and tune for the sound they want. I've actually heard that last part as an argument against tube rolling.

Edited by Rjk1972
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with a specific tube and tune for the sound they want. I've actually heard that last part as an argument against tube rolling.

 

That's kind of what's going on in the back of my mind.

 

Designer "X" creates a circuit for a tube item....  sells it to a customer.

 

Customer rolls some tubes in it....and changes the sound from what Designer "X" originally intended.

 

Did he (designer) intend for it to have the specific sound as created by the tubes he specifically inserted?

 

Does he care that someone altered the flavor of his sound by swapping tubes?

 

If you swap the tubes to alter the flavor of the sound, and this sound isn't what the designer intended, is the amp actually now "less" of an amp than what he felt its potential was?

 

 

Part of me has to think that 'back in the day', they simply designed the circuits and slapped the appropriate tube into it.   

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For me "back in the day" has not changed in 5 decades!!!  Any design has to start with a concept such as the required power to properly drive the speaker with which the amp is going to be used.  Then a decision has to be made as to the type of sound the person desires as different circuit arrangements will yield definite sonic differences (such as SET vs. SEP, push-pull pentodes vs. push-pull triodes, and so on).  Once the power question and type of circuit is settled, then we go to the suitable tube candidates to satisfy that requirement.  And, within that latter category, we have to decide on cost.  Some folks don't want to be using output tubes costing $200 each!  Regarding preamps, again we have to know what it will be used with.  I'm not going to design a high gain preamp capable of an output of 25V if the amp with which it is going to be used has a sensitivity of only 200 millivolts for full output.  As to rolling tubes, I personally don't consider that worthwhile.  In numerous, blind, listening tests over the years most guys have had trouble differentiating subtle variations in tubes.  There's a lot of snake oil out there about tubes having black plates vs. gray plates making a huge difference in sound (the color difference is simply due to different heat dissipation coatings used on the plate), that the shape of the getter or number of getters affects the sound, or that a $400 Telefunken 12AU7 ALWAYS sounds better than an affordable Sylvania.  Perceived sonic differences in cases like that are often proportional to how much the person spent on the "better" tube.  Sure, if a particular tube is noisy due to excessive gas (something I can relate to personally) switching to one which is within spec will be an improvement.  So, that's my philosophy.  Others will have a different perspective.  And, of course, this discussion has to include the issue of  "audiophile grade" caps and resistors as well.  I won't get into that side of things.

Maynard

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Some folks don't want to be using output tubes costing $200 each! 

 

If you can (today) buy a power tube that cost $200 each, you can also buy some that cost more....or less.

 

So, do you as a designer/builder, "care" which brand 300B someone puts into your designs, as long as your design was made for a 300B?

 

If someone gives you an unlimited budget, do you design to the specific (brand and maybe NOS verses current production) tube or are you more concerned with just getting the circuit right?

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As to rolling tubes, I personally don't consider that worthwhile.

 

That's kind of my take on the process which is why I'm wondering what a designer thinks.  I just can't for the life of me think there was as much worrying about brands 'back in the day' however, I don't pretend to know anything about what happened then. 

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I love your posts Coyotee. Personally, if I were designing an amp, I would design it for beauty. This means I would have a specific brand and look in mind. I would want it to sound better than any amp ever conceived, but that would be second. 

 

Form follows function is for the dull. I really dig Steam Punk stuff even though I am very very far removed from that sub-culture.

Edited by mustang guy
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I've always thought the difference between good NOS tubes wasn't huge but between a good NOS Tele or Sylvania and say a JJ 12ax7 was noticeable. That and some amps can benefit from a better rectifier tube. Though I have come to find out lately that the design of an amp dictates if rectifier tube rolling will make a difference. Then of course there is reliability and longevity. Big difference between NOS and current production tubes.

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