First Budgie Preamplifier Post

arduino based linestage using 12B4 tubes

Re: First Budgie Preamplifier Post

Postby IceFyre13th » Mon Feb 17, 2014 12:40 pm

Thanks, I will take pictures during and after the build.....if anyone wants to duplicate it I will post the front panel express files and a "cutting" guide for the wood on the Hammond chassis.

That is on area I am going to have to take my time on, cutting the wood frame (that is assembled) should be moderately easy as I made most of the cuts with standard drill sizes.....some I will just have to connect the holes with a jig saw.

The chassis, with front panel parts costs more then what goes inside.....but I think its worth it.
Last edited by IceFyre13th on Tue Feb 18, 2014 11:16 am, edited 1 time in total.
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Re: First Budgie Preamplifier Post

Postby kku » Mon Feb 17, 2014 7:23 pm

Just a crazy thought. While 1626 may not have as much gain as 12B4, 12B4 and 1626 have comparable electric values. Which voltage/current values does Budgie run the 12B4s? Will 1626 be short lived in Budgie?

From Tung Sol 1626 datasheet...
Heater current = 0.25 Amp,
Max Plate V = 250V,
Plate Current = 25 mA,
Plate dissipation = 5 W,
Grid V= -32V,
Max Grid V= -150V.
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Re: First Budgie Preamplifier Post

Postby Shannon Parks » Mon Feb 24, 2014 4:20 pm

kku wrote:Just a crazy thought. While 1626 may not have as much gain as 12B4, 12B4 and 1626 have comparable electric values. Which voltage/current values does Budgie run the 12B4s? Will 1626 be short lived in Budgie?


The 1626 just doesn't have the high perveance that the 12B4 does, which is the ability to draw current with low voltages. Heck, hardly any other tube does. The plate voltage on the 12B4s is around 17V at 5mA.

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Re: First Budgie Preamplifier Post

Postby highflyin9 » Fri Apr 11, 2014 11:18 am

Great looking project Shannon, congrats on the nice shiny new build :) I've been slacking on my DIY (graduate work has thrown a monkey wrench in my projects) so I didn't see this til now.

I noticed the motorized pot, is there a remote that will interface with the unit?
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Re: First Budgie Preamplifier Post

Postby Shannon Parks » Thu Apr 17, 2014 5:53 am

highflyin9 wrote:Great looking project Shannon, congrats on the nice shiny new build :) I've been slacking on my DIY (graduate work has thrown a monkey wrench in my projects) so I didn't see this til now.

I noticed the motorized pot, is there a remote that will interface with the unit?


The stock code uses the Apple Remote. I thought a minimalistic, machined remote was just too cool. ;) But there's a learning mode which permits using any remote, and is particularly suited for those "extra" buttons on remotes you already use.

BTW, the Budgie Preamplifier will be featured in audioXpress June 2014 with an article written by me describing the DIY benefits of the Arduino microcontrollers. Pretty exciting!

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Re: First Budgie Preamplifier Post

Postby culexus » Mon Apr 21, 2014 1:37 pm

I did also order me a budgi preamp and all the parts from mouser and ebay :) looking forward to do the build:)

The only thing Im missing out on is how to tune the pot`s for the tube`s. Any tip on how this is done? This will be my first tube amp build.

And one more thing, is there any youtube video of the amp. Would be nice to see the amp up and running and how the lcd works and so on. :)
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Re: First Budgie Preamplifier Post

Postby TomMcNally » Mon Apr 21, 2014 3:04 pm

In an earlier post in this thread, Shannon Parks says:

**********
The 12B4s are biased around 5mA, determined by the active load current source ((red LED - Vbe of transistor) / 210 ohm resistor). The cathode trimpot then adjusts for lowest distortion. It can initially be adjusted to 350 ohms. Using a input sine wave (from a cell phone function generator app) adjust for maximum output measured with any DMM. This will be the lowest distortion. But I plan to go through my stash of RCA, Sylvania and GE 12B4 tubes. I think the tubes bias similarly from the same manufacturer. So RCAs might 350 ohms and GEs 275 ohms, etc. I'll do this soon. The plate voltage will be in the 15V to 19V range. Any higher will risk early clipping at the CCS.
***********

I adjusted mine for 300 ohms. Sounds sweet.
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Re: First Budgie Preamplifier Post

Postby Shannon Parks » Tue Apr 22, 2014 9:30 am

culexus wrote:And one more thing, is there any youtube video of the amp. Would be nice to see the amp up and running and how the lcd works and so on. :)


This is on my "to do" list. I think the bias procedure lends itself to YouTube very well, too.

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Re: First Budgie Preamplifier Post

Postby highflyin9 » Tue Apr 29, 2014 2:22 pm

Shannon Parks wrote:
highflyin9 wrote:BTW, the Budgie Preamplifier will be featured in audioXpress June 2014 with an article written by me describing the DIY benefits of the Arduino microcontrollers. Pretty exciting!

Very exciting indeed! I updated my subscription to ensure I get a copy.

BTW, I just finshed up my Budgie SE on a copper plate, it's purdy ;) I'll be getting some pics up shortly. The headphone output was sounding pretty excellent with my Sennheiser Momentums.
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Re: First Budgie Preamplifier Post

Postby Shannon Parks » Tue Apr 29, 2014 4:00 pm

highflyin9 wrote:Very exciting indeed! I updated my subscription to ensure I get a copy.


Now bumped to July. Hopefully a better article won't keep bumping it indefinitely - (lol)

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Re: First Budgie Preamplifier Post

Postby dannyr » Wed Jul 02, 2014 9:48 pm

Wow. what a nice project. If it had a bass cut and balance I probably couldn't resist. I find stuff like FM sounds much better cutting the low end.

Wait, is Flat 6db a cut?

Anyway, really really impressive.
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Re: First Budgie Preamplifier Post

Postby Shannon Parks » Sat Jul 05, 2014 6:26 am

dannyr wrote:Wow. what a nice project. If it had a bass cut and balance I probably couldn't resist. I find stuff like FM sounds much better cutting the low end.

Wait, is Flat 6db a cut?

Anyway, really really impressive.


Thanks! It's a just a first-order bass roll-off due to the AC coupled input (cap value could be changed). I plan to upload the LTSpice sims so one can easily simulate & modify the frequency response in Flat and Bass Boost modes.

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Re: First Budgie Preamplifier Post

Postby Auricle » Mon Jul 28, 2014 4:17 pm

D14 ?

6.2V Zener diode D14 appears in the parts list, but not on the schematics. It appears on a pic of Shannon's PCB on eBay, at one end of RL3, the o/p muting relay. It does not appear on Shannon's PCB pics in this thread.

There must be a story behind this, and I am curious. Why, and where is it connected. Thanks.

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Re: First Budgie Preamplifier Post

Postby Auricle » Tue Jul 29, 2014 2:31 am

The IRremote library seems to be missing from budgiesketchv0_05.zip.

I was able to download IRremote library from https://github.com/shirriff/Arduino-IRremote. After that, I was able to successfully install the library and Verify/Compile budgiesketchv0_05.
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Re: First Budgie Preamplifier Post

Postby Shannon Parks » Tue Jul 29, 2014 10:20 am

Auricle wrote:D14 ?

6.2V Zener diode D14 appears in the parts list, but not on the schematics. It appears on a pic of Shannon's PCB on eBay, at one end of RL3, the o/p muting relay. It does not appear on Shannon's PCB pics in this thread.

There must be a story behind this, and I am curious. Why, and where is it connected. Thanks.

Regards,
Auricle


Nice catch, Auricle! This was a Rev A addition to the circuit that helps the relay's coil to collapse faster. So when power is disconnected the mute circuit works much faster with much less of a thump. I'll look into my schematics and update the drawing on the site. D14 is located near RL3 and D7.

A nice web write up on the theory:
http://jumperone.com/2011/10/using-relays/

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