It is currently Mon Mar 16, 2020 11:37 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 72 posts ]  Go to page Previous  1, 2, 3, 4, 5
Go to page Previous  1, 2, 3, 4, 5
Author Message
Post subject: Re: Build Your Own Amp - 2
Posted: Wed Aug 28, 2013 6:21 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
Yeah... but it's getting too hot to sit over a soldering iron. I end up doing most of my circuit work after midnight. Vampire amp tech. :lol:

Be interested in your opinion of those Jupiter Yellow Vintage caps. A definite upgrade to the RI Sprague (SBE) Orange Drops, IMHO.


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Build Your Own Amp - 2
Posted: Wed Aug 28, 2013 6:48 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Mon Jan 12, 2009 4:50 pm
Posts: 7998
Location: ʎɹʇunoɔ ǝsoɹ pןıʍ
bluesky636 wrote:
BMW,

I hoped you get started soon. If you have any problems, you know where to come. This forum has been kind of lame these last few weeks (the ENTIRE forum, not just modern amps) and we need a good build thread to liven things up. :mrgreen:
:lol:
Prolly be another week or so.

_________________
Image
Just think of how awesome a guitar player you could have been by now if you had only spent the last 10 years practicing instead of obsessing over pickups and roasted maple necks.


Top
Profile
Post subject: Re: Build Your Own Amp - 2
Posted: Wed Aug 28, 2013 9:43 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
The floor will be yours then.

:mrgreen:

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Build Your Own Amp - 2
Posted: Thu Aug 29, 2013 2:20 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Mon Jan 12, 2009 4:50 pm
Posts: 7998
Location: ʎɹʇunoɔ ǝsoɹ pןıʍ
Well, my Bias-Rite just arrived.
I guess I'll be ready.



Image

_________________
Image
Just think of how awesome a guitar player you could have been by now if you had only spent the last 10 years practicing instead of obsessing over pickups and roasted maple necks.


Top
Profile
Post subject: Re: Build Your Own Amp - 2
Posted: Thu Aug 29, 2013 4:52 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Sat Mar 20, 2010 2:30 pm
Posts: 792
Location: A Land Downunder
Hey Fellas, really appreciate the comments about my builds.

Hey Beemer, the kit looks awesome! 8)

Here's how to check the tube dissipation if you want to as an excersise (it's good to know anyways). Just follow the steps through and substitute your numbers for mine, it's really just using Ohms law to figure it out (Current=Voltage/Resistance).

For a 5E3 Design, when you get to the step about subtracting the screen current, you can just use my figure (3.5ma) and you'll be real close on the final numbers anyway.


I measured the following to start with:
Voltage across Cathode Resistor = 21 volts
Actual Measured Resistance of Cathode Resistor = 250 Ohms
Plate Voltage (Pin3 to Ground) = 357 volts

Then plug the numbers in

Plate Current calculations:
Cathode Resistor Voltage (21 volts) / Cathode Resistor Ohms (250) = 0.084 (84 milliamps)
This is the Cathode Current (including screen current) for BOTH Tubes.

Subtract the screen current (measured to be 3.5ma) = 80.5ma

Divided by 2 (tubes) = 40.25ma (.04025 A) Plate Current per tube

Idle Dissipation calculations:
Plate Voltage (357 volts) - Cathode Resistor Voltage (21 volts) = 336 volts
multiplied by Plate Current (.04025 A) = 13.5 watts


Hope that helps when you get to the final check up stages of your build. 8)

Cheers,
Snowy


Top
Profile
Post subject: Re: Build Your Own Amp - 2
Posted: Thu Aug 29, 2013 5:20 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
No457 Snowy wrote:
Hey Fellas, really appreciate the comments about my builds.

Hey Beemer, the kit looks awesome! 8)

Here's how to check the tube dissipation if you want to as an excersise (it's good to know anyways). Just follow the steps through and substitute your numbers for mine, it's really just using Ohms law to figure it out (Current=Voltage/Resistance).

For a 5E3 Design, when you get to the step about subtracting the screen current, you can just use my figure (3.5ma) and you'll be real close on the final numbers anyway.


I measured the following to start with:
Voltage across Cathode Resistor = 21 volts
Actual Measured Resistance of Cathode Resistor = 250 Ohms
Plate Voltage (Pin3 to Ground) = 357 volts

Then plug the numbers in

Plate Current calculations:
Cathode Resistor Voltage (21 volts) / Cathode Resistor Ohms (250) = 0.084 (84 milliamps)
This is the Cathode Current (including screen current) for BOTH Tubes.

Subtract the screen current (measured to be 3.5ma) = 80.5ma

Divided by 2 (tubes) = 40.25ma (.04025 A) Plate Current per tube

Idle Dissipation calculations:
Plate Voltage (357 volts) - Cathode Resistor Voltage (21 volts) = 336 volts
multiplied by Plate Current (.04025 A) = 13.5 watts


Hope that helps when you get to the final check up stages of your build. 8)

Cheers,
Snowy



Hi, Snowy. :D

Weber has a simple calculator (last one before the Jim Jones' Bias Tables) for calculating plate dissipation for a cathode biased amp:

http://www.webervst.com/tubes1/calcbias.htm

_________________
Bill

Image


Top
Profile
Post subject: Re: Build Your Own Amp - 2
Posted: Thu Aug 29, 2013 5:26 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Sat Mar 20, 2010 2:30 pm
Posts: 792
Location: A Land Downunder
bluesky636 wrote:
No457 Snowy wrote:
Hey Fellas, really appreciate the comments about my builds.

Hey Beemer, the kit looks awesome! 8)

Here's how to check the tube dissipation if you want to as an excersise (it's good to know anyways). Just follow the steps through and substitute your numbers for mine, it's really just using Ohms law to figure it out (Current=Voltage/Resistance).

For a 5E3 Design, when you get to the step about subtracting the screen current, you can just use my figure (3.5ma) and you'll be real close on the final numbers anyway.


I measured the following to start with:
Voltage across Cathode Resistor = 21 volts
Actual Measured Resistance of Cathode Resistor = 250 Ohms
Plate Voltage (Pin3 to Ground) = 357 volts

Then plug the numbers in

Plate Current calculations:
Cathode Resistor Voltage (21 volts) / Cathode Resistor Ohms (250) = 0.084 (84 milliamps)
This is the Cathode Current (including screen current) for BOTH Tubes.

Subtract the screen current (measured to be 3.5ma) = 80.5ma

Divided by 2 (tubes) = 40.25ma (.04025 A) Plate Current per tube

Idle Dissipation calculations:
Plate Voltage (357 volts) - Cathode Resistor Voltage (21 volts) = 336 volts
multiplied by Plate Current (.04025 A) = 13.5 watts


Hope that helps when you get to the final check up stages of your build. 8)

Cheers,
Snowy



Hi, Snowy. :D

Weber has a simple calculator (last one before the Jim Jones' Bias Tables) for calculating plate dissipation for a cathode biased amp:

http://www.webervst.com/tubes1/calcbias.htm



G'day Mate,
Yeah, I'm old fashioned and a Glutton for punishment..... :oops:


Top
Profile
Post subject: Re: Build Your Own Amp - 2
Posted: Thu Aug 29, 2013 8:42 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
I also like to at least be able to do it without a probe. It is kind of cool, and tech-y, and good brain exercise. I guess that the probe reduces the chances for error, plus the copper pipes on that Bias Rite are so heavy-duty. 8)

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


Top
Profile
Post subject: Re: Build Your Own Amp - 2
Posted: Thu Aug 29, 2013 10:00 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
No457 Snowy wrote:
G'day Mate,
Yeah, I'm old fashioned and a Glutton for punishment..... :oops:


Everyone here knows I love math, but sometimes I just like to KISS. :lol: :lol: :lol: :lol:

_________________
Bill

Image


Top
Profile
Post subject: Re: Build Your Own Amp - 2
Posted: Sat Sep 07, 2013 10:09 am
Offline
Rock Star
Rock Star
User avatar

Joined: Mon Jan 12, 2009 4:50 pm
Posts: 7998
Location: ʎɹʇunoɔ ǝsoɹ pןıʍ
Well, it looks like I won't be starting my build anytime soon after all. It's been a busy summer but that's over now and I just got called away to work up in Fort Mac. I was hoping to take something closer to home but I need the money after having taken the summer off and didn't really cut down on my spending. I apologise for promising an exciting new build thread and then reneging on the promise. Living away for several weeks with nothing to do in the evenings will give me the time to read that amp book that I was going to read so at least I'll be doing SOMETHING to prepare. If all goes well I'll return with a little more knowledge and possibly a better ability to understand some of the more technical things I see you fellows discussing around here.

_________________
Image
Just think of how awesome a guitar player you could have been by now if you had only spent the last 10 years practicing instead of obsessing over pickups and roasted maple necks.


Top
Profile
Post subject: Re: Build Your Own Amp - 2
Posted: Sat Sep 07, 2013 12:00 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
We'll be waiting. :D

_________________
Bill

Image


Top
Profile
Post subject: Re: Build Your Own Amp - 2
Posted: Sat Sep 07, 2013 12:03 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
bluesky636 wrote:
We'll be waiting. :D


+1

No sweat -- it'll give us something to look forward to later in the year.

Rawk on!

8)

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 72 posts ]  Go to page Previous  1, 2, 3, 4, 5
Go to page Previous  1, 2, 3, 4, 5

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: Google [Bot] and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: