Home | High-End Audio Reviews | Audiophile Shows | Partner Mags | Daily News | Search     

  High-End Audiophile Review Magazine & Audio Equipment Reviews

  High-End Audiophile Equipment Reviews
  Gear Reviews, News, Show Reports, And More!

  Celebrating 28 Years Of Service To Music Lovers



New York Audio Design Exhibition


 5842 (417A) "Spud" Amp
Pete Boser


  This amp is based on the designs of Lucas Cant of Black Art Audio in Victoria, Australia. Starting on the next page are his comments and schematics, taken from his website (with his permission), which is located at: http://www.jeack.com.au/~lucas/.

I attended both prior NY Noise events, and came away both times very inspired by what I saw. The depth of innovation and knowledge of the exhibitors is very impressive, and a bit intimidating to someone as inexperienced and untrained as me. With each aspect of this little amp that I experiment with, I learn a lot - much more than I do by just reading of the diy exploits of others. My purpose in exhibiting this amp is not to impress anyone, or even to teach anyone anything. Rather, I hope that it will inspire or encourage others to get off the fence and start building. 

As an inexperienced Joelist lurker, I started with kits from Bottlehead, and lots of reading and questioning. Finally, I saw the spud amp schematic, and got brave enough to try to breadboard the amp. I used some Allen Bradley carbon composition resistors I had and some other resistors and caps I got from Radio Shack. Based on the admonitions from the Joelist and other sources, I carefully applied 100 ohm resistors to each of the four grid pins on each tube. (These are from Radio Shack too.) I used a pair of Tango U808 output transformers, set up for a 5Kohm primary.

Due to fear and ignorance, I chose to avoid trying to put together a power supply, and instead used a Hickock tube lab power supply I bought on eBay. When I hooked up the 6.3 volt filament supply, I got too high a voltage. I had the same problem with a separate filament transformer I had, so I put some big resistors (from Radio Shack, of course) in line until I got in the right area. Remnants of this effort have been left for discovery by future audio archeologists.

At some point, I spotted the batteries used in my daughter's Barbie Jeep, one of those little Power Wheels vehicles for preschoolers. I charged one up, slapped it in there, and found it read exactly 6.3 volts! It also eliminated the filament hum, so I kept it. It seems to last a long time without discharging, so it's not so bad that I have to disconnect it and hook it up to the Barbie charger.

Next, while visiting the local boom-car stereo and electronics parts emporium, I finally found the type of 2 volt lead acid batteries that Lucas mentions on his website. Although they had the "D" size version, they also had bigger ones, and so I figured more is better, and I took the bigger ones. I hooked them up with some clipleads, and was amazed that the amp still worked! This has temporarily exorcised my desire for expensive cathode bypass caps, but I guess at some point I'd like to compare both bias configurations.

Of course the next step is a power supply. As I type this I've recently experimented with using a 115V isolation transformer and a diode bridge, but I must have miswired it, so it needs more work. I also will try something along the lines of Lucas' schematic with a higher voltage transformer I have on hand and a Variac, but my knowledge of my ignorance makes me want to take it very slow.

Ultimately, my goal is to cobble together a power supply, try some better quality parts, and then duplicate the whole thing in a package that looks like an amplifier, can fit on a shelf, and is not a danger to family members. When I do so, this breadboard will likely remain as a first stage of an amp using other triodes as output tubes. Better look for some more plywood!












































Quick Links

Audiophile Review Magazine
High-End Audio Equipment Reviews


Equipment Review Archives
Turntables, Cartridges, Etc
Digital Source
Do It Yourself (DIY)
Cables, Wires, Etc
Loudspeakers/ Monitors
Headphones, IEMs, Tweaks, Etc
Ultra High-End Audio Reviews


Enjoy the Music.TV


Editorials By Tom Lyle
Viewpoint By Roger Skoff
Viewpoint By Steven R. Rochlin
Various Think Pieces
Manufacturer Articles

Show Reports
AXPONA 2023 Show Report
Salon Audio Montréal Audiofest 2023
CanJam Singapore 2023 Report
Florida Intl. Audio Expo 2023
Capital Audiofest Show 2022
KL International AV Show 2022
Toronto Audiofest Show 2022
CanJam SoCal 2022 Show Report
Pacific Audio Fest 2022 Report
T.H.E. Show 2022 Report
HIGH END Munich 2022
...More Show Reports


Audiophile Contests
Cool Free Stuff For You
Tweaks For Your System
Vinyl Logos For LP Lovers
Lust Pages Visual Beauty


Resources & Information
Music Definitions
Hi-Fi Definitions


Daily Industry News

High-End Audio News & Information


Partner Print Magazines
Australian Hi-Fi Magazine
hi-fi+ Magazine
HiFi Media
Sound Practices
The Absolute Sound
VALVE Magazine


For The Press & Industry
About Us
Press Releases
Official Site Graphics


Contests & Our Mailing List

Our free newsletter for monthly updates & enter our contests!




Home   |   Industry News   |   Equipment Reviews   |   Press Releases   |   About Us   |   Contact Us


All contents copyright©  1995 - 2023  HighEndAudio.com and Enjoy the Music.com®
May not be copied or reproduced without permission.  All rights reserved.