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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 11:47 am
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Oh yeah, those tube ratings are soooooo scientifically derived......

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:lol:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 12:09 pm
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:lol:

Seriously, GT and Mesa Boogie use computerized tube testers to rate tubes. Mesa Boogie even names their tester "Robo Tube". Most suppliers use a Maxi-Matcher, some use tube testers like an Amplitrex, some use curve tracers. That's as scientific as you can get.

You use a tube tester don't you?

I'm not sure why I'm having such a hard time explaining the ratings, it is a simple matter of Plate current draw at a fixed grid voltage, with a fixed Plate voltage. The numbers (Ip usually), are used to compare tubes as weaker or stronger.

Besides, the wheel always favors the house. :lol:

If you're aiming for "Tropical", I hope your aim is true, for his sake! :shock:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 12:54 pm
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shimmilou wrote:
:lol:

Seriously, GT and Mesa Boogie use computerized tube testers to rate tubes. Mesa Boogie even names their tester "Robo Tube". Most suppliers use a Maxi-Matcher, some use tube testers like an Amplitrex, some use curve tracers. That's as scientific as you can get.

You use a tube tester don't you?

I'm not sure why I'm having such a hard time explaining the ratings, it is a simple matter of Plate current draw at a fixed grid voltage, with a fixed Plate voltage. The numbers (Ip usually), are used to compare tubes as weaker or stronger.

Besides, the wheel always favors the house. :lol:

If you're aiming for "Tropical", I hope your aim is true, for his sake! :shock:


But it is only Groove Tubes AFAIK that takes those ratings and "translates" them to some arbitrary "grade". So what grade is a tube rated at 25 or 40 or 45 or 60?

As far as overthinking it goes, what could be simpler than buying a matched set of tubes and biasing them properly to the desired % of max plate dissipation? What are the chances that the optimum bias in your amp will match the Ip of a tube measured at some arbitrary plate voltage and grid current? Most tube testers only supply a plate voltage in the neighborhood or 400 VDC. How does all this translate to an amp with a plate voltage of 475 VDC or more?

Eurotubes has used both an Amplitrex and Maxi-Matcher. Now they use the “Kamna Matcher”.

http://www.eurotubes.com/eurotubes-test ... rranty.htm

I will agree that in a non-adjustable fixed bias amp, you either need to know the tube rating or change components to bias the tube properly. In an adjustable fixed biased amp, what purpose does the rating serve?

In my opinion, the OP has been on an Easter egg hunt trying to find the perfect tube instead of buying a well matched set from a reputable dealer, biasing them properly (easily done in an HRD) and maybe throwing in a low gain preamp tube. Isn't that what we usually tell people when they complain that the HRD is too loud at 3? Why is this situation any different?

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 1:04 pm
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Retroverbial wrote:
Oh yeah, those tube ratings are soooooo scientifically derived......

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:lol:

Arjay


I tend to prefer "Toasty". "Tepid" and "Chilly" are too close to crossover distortion. Tubes start to redplate at "Barbecue". :lol: :lol: :lol: :lol:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 1:05 pm
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bluesky636 wrote:
I tend to prefer "Toasty". "Tepid" and "Chilly" are too close to crossover distortion. Tubes start to redplate at "Barbecue". :lol: :lol: :lol: :lol:


And the glass envelope melts at "Inferno".

:wink:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 1:13 pm
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Retroverbial wrote:
bluesky636 wrote:
I tend to prefer "Toasty". "Tepid" and "Chilly" are too close to crossover distortion. Tubes start to redplate at "Barbecue". :lol: :lol: :lol: :lol:


And the glass envelope melts at "Inferno".

:wink:

Arjay


What's hotter? Inferno or Napalm? At what point does the entire amp just vaporize?











:lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 1:56 pm
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bluesky636 wrote:
At what point does the entire amp just vaporize?


For that, the tubes must be rated "MAGMA".

And that rating is reserved solely for the KT88/6550 bottles when used in an Ampeg SVT or Fender PS400.

:wink:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 2:51 pm
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Lookout Smothers Brothers, you've got competition. :lol:

Or, Burns and Allen for you older folks. :mrgreen:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 3:42 pm
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No harm, no foul. We love amp humor just as much as we love amps themselves.

:wink:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 6:03 pm
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[quote="bluesky636"]

What's hotter? Inferno or Napalm? At what point does the entire amp just vaporize?[quote]

When you engage the vaporizer switch. Didn't you watch the Fender promotional video? :wink:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 6:04 pm
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BTW. Got in touch with the Tubestore and they will send me the correct tube. For free. They apologized too.

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 7:28 pm
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I could never figure out how all us geezers survived without all the tube grading BS. Like Bill said. You buy a pair of tubes that are matched pretty closely and properly bias them. I still think GT is a load. So far I've been running JJ's from Bob at Eurotubes in all my amps for the past four years or so and never had a problem. They sound great. As far as the HRDlx getting really clean, mine always had some breakup by the time you hit 3 on the volume dial no matter what I did to it. If you want clean, I recommend either a Twin or maybe an Ampeg. You can get really wrapped up in all the techno crap and convince yourself it doesn't sound good. :wink:

As far as tubes go, I run mine like a Lava Lamp. :lol: Lava Lamp trumps vaporizer every time.

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Fri Jan 03, 2014 8:54 pm
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63supro wrote:
I could never figure out how all us geezers survived without all the tube grading BS. Like Bill said. You buy a pair of tubes that are matched pretty closely and properly bias them.


+1000

I'm more confident buying a matched pair or quartet of vintage NOS JAN's than I'll ever be with a set of contemporary bottles that come with a five-page "grade" report signed by Marconi himself.

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sat Jan 04, 2014 2:04 am
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Can any of you tell us how in the world you can possibly match tubes? Is there some kind of magician that can do that? Witches? :?

Why, when I was a kid we just threw an old pair of socks in our amps and called it a matched pair, and we loved it. We didn't have hospitals either, so when you had an accident, you just limped around without any medical attention, and we loved it. We didn't even have houses, we just lived in an old cardboard box in the middle of the street, and everyday when we woke up we would scrub the streets clean with our bare hands until our hands were just bloody stumps, and we loved it.

The kids these days with their fancy-smancy voodoo testing equipment have it way too easy.

:lol:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sat Jan 04, 2014 7:43 am
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shimmilou wrote:
Can any of you tell us how in the world you can possibly match tubes? Is there some kind of magician that can do that? Witches? :?


Nobody is arguing about matching tubes. It is the assignment of arbitrary "grades" to tubes that is the issue.

Although some of the information is out of date and links don't work, here is an interesting discussion on tube ratings:

http://www.guitaramplifierblueprinting.com/Rating.html

One area that I have a problem with is this paragraph:

"Basically, a #1 will distort sooner, and a #10 later. If, for example, with a mid range tube, say a #5, makes your amp start to break in the output section at a volume setting on the amp of "4", then with a lower number tube, like a #2, your amp would have a same sort of break into output distortion at say a volume setting of "3". With a higher tube, such as an #8, then you amp would stay clean to about perhaps "6" on the volume."

The volume setting where an amp starts to break up will be significantly impacted by the pot curve of the volume control. As an excellent example, when I first built my 5F6A clone, the normal and bright volume controls were audio taper. With the guitar volume maxed, the amp would not break up until about 8 or 9. After I changed the volume controls to the correct vintage spec of linear taper, the amp now starts to break up between 4 and 6 (I run both controls on 6 and control volume with the guitar). No changes were made in tube bias.

Let's not get into a discussion of preamp and PI design which I believe has an even greater impact on amp distortion than just power tube rating. Unless you want to, of course. :lol:

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