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My Homebuilt "Mid-Century" Style Amp

Little Wolf

Little Wolf

New Member
Hi All,

This is my first AK post. Just wanted to share a recently completed project of mine: a homebuilt transistor-tube hybrid integrated stereo amplifier in the style of an early 1960's household hi-fi stereo set.

The set was built as a modular system; with the exception of the power supply (which was built from scratch), all sections were built from kit circuit boards. The preamp and phono preamp modules use tubes of the 12AX7 and 12AU7 types, while the power amp modules use the JLH 1969 open-source design, an all-transistor circuit by John Linsley Hood of England in 1969 (the JLH 1969 was said to be the best solid state amp ever designed and is about as close as one can get to that of a tube amp in terms of sound quality). The output transistors are 2N3055 in Class A push-pull, while the driver transistors are 2N3866 VHF/UHF RF transistors which improved the sound quality by A LOT (I did not use the 2N1711 supplied with the kit). Also, instead of soldering the driver transistor directly to the circuit board, I used NOS transistor sockets; this would allow me to try various NPN BJT's when I have some time and also allows for easy trouble shooting in the event of failure. The outer case was made by repurposing the empty shell of a gutted Pioneer CX-770s from 1994 (a control box for a Pioneer BPC stereo system).

Check out http://www.alvenh.com/misc-projects/tubeamp for full story (includes links to two demonstration videos).

cover_photo_tube_amp.jpg

Tube-Amp-Front-Panel-768x576.jpg


This is how it all started:
before001-768x576.jpg
 
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spark1 said:
Looks like very fine work.

Did you fabricate the front panel?

Welcome to AK.
Click to expand...

Thanks. And for the most part, yes. The sub-panel, however, was cut to size by a sheet metal shop because 1/8" was too thick for me to cut but everything else (including the top piece of the front panel) was done at home, including drilling the sub-panel.
 
spark1 said:
Impressive. How was the lettering done?
Click to expand...
The part that reads "HUSKY" was done by using letter stickers (from Michael's craft store) as reverse spray paint stencil while the labels were made by transferring toner printed on an old sheet of sticker backing to tape, then trimming to size and sticking in appropriate spots. The whole panel was the covered with a couple of coats of Krylon clear gloss to protect the decals from peeling.
 
Little Wolf said:
Hi All,

This is my first AK post. Just wanted to share a recently completed project of mine: a homebuilt transistor-tube hybrid integrated stereo amplifier in the style of an early 1960's household hi-fi stereo set.

The set was built as a modular system; with the exception of the power supply (which was built from scratch), all sections were built from kit circuit boards. The preamp and phono preamp modules use tubes of the 12AX7 and 12AU7 types, while the power amp modules use the JLH 1969 open-source design, an all-transistor circuit by John Linsley Hood of England in 1969 (the JLH 1969 was said to be the best solid state amp ever designed and is about as close as one can get to that of a tube amp in terms of sound quality). The output transistors are 2N3055 in Class A push-pull, while the driver transistors are 2N3866 VHF/UHF RF transistors which improved the sound quality by A LOT (I did not use the 2N1711 supplied with the kit). Also, instead of soldering the driver transistor directly to the circuit board, I used NOS transistor sockets; this would allow me to try various NPN BJT's when I have some time and also allows for easy trouble shooting in the event of failure. The outer case was made by repurposing the empty shell of a gutted Pioneer CX-770s from 1994 (a control box for a Pioneer BPC stereo system).

Check out http://www.alvenh.com/misc-projects/tubeamp for full story (includes links to two demonstration videos).

cover_photo_tube_amp.jpg

Tube-Amp-Front-Panel-768x576.jpg


This is how it all started:
before001-768x576.jpg
Click to expand...
Spectacular wish I knew anything about repairing or fixing amplifiers. Welcome to ak, which speakers are you going to use with this music amplifier ? Or do you plan on using it for more stuff .
Amazing craftsmanship, and husky logo. My favorite dog type .
 
Little Wolf said:
Hi All,

This is my first AK post. Just wanted to share a recently completed project of mine: a homebuilt transistor-tube hybrid integrated stereo amplifier in the style of an early 1960's household hi-fi stereo set.

The set was built as a modular system; with the exception of the power supply (which was built from scratch), all sections were built from kit circuit boards. The preamp and phono preamp modules use tubes of the 12AX7 and 12AU7 types, while the power amp modules use the JLH 1969 open-source design, an all-transistor circuit by John Linsley Hood of England in 1969 (the JLH 1969 was said to be the best solid state amp ever designed and is about as close as one can get to that of a tube amp in terms of sound quality). The output transistors are 2N3055 in Class A push-pull, while the driver transistors are 2N3866 VHF/UHF RF transistors which improved the sound quality by A LOT (I did not use the 2N1711 supplied with the kit). Also, instead of soldering the driver transistor directly to the circuit board, I used NOS transistor sockets; this would allow me to try various NPN BJT's when I have some time and also allows for easy trouble shooting in the event of failure. The outer case was made by repurposing the empty shell of a gutted Pioneer CX-770s from 1994 (a control box for a Pioneer BPC stereo system).

Check out http://www.alvenh.com/misc-projects/tubeamp for full story (includes links to two demonstration videos).

cover_photo_tube_amp.jpg

Tube-Amp-Front-Panel-768x576.jpg


This is how it all started:
before001-768x576.jpg
Click to expand...
Spectacular wish I knew anything about repairing or fixing amplifiers. Welcome to ak, which speakers are you going to use with this music amplifier ? Or do you plan on using it for more stuff .
Amazing craftsmanship, and husky logo. My favorite dog type .
 
It looks so much nicer than the original Pioneer box. And probably sounds much better as well.
Well done, I always appreciate the attention to aesthetics as well as the electronics design.
 
ultumax said:
Spectacular wish I knew anything about repairing or fixing amplifiers. Welcome to ak, which speakers are you going to use with this music amplifier ? Or do you plan on using it for more stuff .
Amazing craftsmanship, and husky logo. My favorite dog type .
Click to expand...

Thanks. I am using a pair of Mission speakers with my homemade amp but I hope to get a matching pair of 50's/60's vintage speakers soon. I will be using my amp with various audio sources including a CD player, my iPod, computer, FM tuner, and even a police band scanner (there is a MONO AUX input for scanners and 2-way radio units). I came up with the husky logo for a previous project (a multi-band crystal set).
 
Welcome to AK
A very impressive effort.
As stated before , after reading the link. Really a labor of love.
It makes doing rebuilds look simple. (Clearly there are exceptions.
I'd be curious to hear that though I couldn't see doing all that fabrication. (Not that my tools or skillset are up to it).
I have projects in queue but I use pre made chassis.
Nice work!
 
nj pheonix said:
Welcome to AK
A very impressive effort.
As stated before , after reading the link. Really a labor of love.
It makes doing rebuilds look simple. (Clearly there are exceptions.
I'd be curious to hear that though I couldn't see doing all that fabrication. (Not that my tools or skillset are up to it).
I have projects in queue but I use pre made chassis.
Nice work!
Click to expand...

Thank-you and yes, I will admit that project diaries and tutorials do make builds look deceptively simple. I've also done rebuilds before as I also collect old radios and vintage tube-type radio communications equipment. Rebuilds can be quite difficult in their own ways, especially if you're dealing with corrosion and broken parts that can't be replaced.
 
Nicely done! That looks better than most commercially produced units.

At some point in the future, I hope to convert a couple Bogen PA tube amps into monoblocks, and also give them a more sophisticated mid-century look. You've given me something to think about design-wise. :-)

Bogen PA amp.jpg
 
Tommy_B said:
Nicely done! That looks better than most commercially produced units.

At some point in the future, I hope to convert a couple Bogen PA tube amps into monoblocks, and also give them a more sophisticated mid-century look. You've given me something to think about design-wise. :)

View attachment 1603340
Click to expand...
Those old Bogen PA tube amps make good guitar amps. In most cases, no modification is needed...just just plug your guitar into the mic jack and play.
 
Man that's awesome I really dig the aesthetic. I honestly wish some manufacturers would get on a mid century styling kick and get away from the super industrial look. My dream scenario would be someone with the knowledge and money buying the rights to Fisher ala what happened with KLH and doing some modern takes on classic fisher designs like the X-202 with the lights and everything.
 
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