I am restarting my effort on this project, after a break of nearly a year.  Not seen in the photo below is a piece of plywood scrap I begged from a neighbor who is rehabbing an old house.  I will use it as the back for the second speaker cabinet. This plywood has been cut, drilled, routed, sanded, and stained.  Finishing of this last speaker part is next.  I am also putting together an order for the remaining passive components that I need for the amp itself. But before I do anything else I must put the speaker cloth on the baffles, and mount the speakers before I poke a hole in them.

Speaker Cabinets for the Funnder Project

It was brought to my attention that I had not posted photos of the pair of speaker cabinets that I am building for this project.  Each cabinet holds a single 12" speaker.  I do not yet know if they will be partially open back, closed back, or rear ported.  I have built two other cabinets like these, using other wood and methods of joinery.  This design was copied from a Roland VGA-5 combo amp because the materials available dictated it.  The 3/4" construction-grade plywood is not preferred material.  But I found an uncompleted card table project in an abandoned rental house I was cleaning out for a real-estate agent.  So here it is.  The dye was mixed with denatured alcohol as a carrying or delivery agent.  The dye applying is now complete for both cabinets.  I am now applying a finish.

While cleaning out a family members basement, I discovered this book below, printed in 1961.  Does this look familiar Private Fred Hegel?

Assembly is complete

Looks finished doesn't it?  As the last 3 photos show, it is not finish.  All of the elements have been mounted.  My effort will slow down a bit now.  I hope to complete the wiring and testing by the end of the year.The 12AX7 on the left side of the chassis is the only planned preamp tube at this point.  Phase inverter is in the middle near the bias adjustment potentiometer.  The open tube socket near the phase inverter is an auxiliary, just in case I can't get proper gain from the single preamp tube.  Only recently did I learn that I don't have four 1614 tubes, but two with the other two being steel-cased 6L6.  Rectification is by bridge as you can see.  On the left of the rear chassis, is an octal socket (with pig tail inserted).  This was in the chassis when I pulled it from the Conn organ, and I decided to leave it in to be used as HV read points.  I wound up with two different capacitor holders.  The silver colored one is preferred but I haven't found a second one yet.  Brian can you help?  So what is the funny bulb near the front of the chassis, you ask?  That is something I've been working on for a while.  I've named it the "hydrophonic ambivalator".  The specifics of its function are secret, but I will say that it enhances the sound of the amp by adding to the ambiance.  I added a mix of turret boards and solder points since the entire preamp hasn't been worked out yet.

Thank you Brian for donating the vintage ShopSmith.

Funnder Chassis is now complete

Sanding, priming, and top coat are now complete.  The top coat is actually engine block paint, and it is actually FORD BLUE.  Next I will begin attaching all of the chassis-mounted components.  I hope to complete this by the end of October this year.  We will see.

Chassis prep continues

Drilling and punching of the Funnder chassis is complete. Stripping, sanding and painting is next.

Two years gone by - New Amp

It's been two years since I last posted here.  I've started a new amp project.  This one will involve combining the Fender Twin Reverb power amp, with the Sunn preamp used in their Sorado, Sonic II, 200s, and Sonic I-40.  An additional twist will be the use of 1614 tubes in place of the 6L6.  I am using a chassis I took from a Conn organ.  In the photos here I've mounted the power and output transformers.  No measuring for everything else.

Vibro Champ now running

Completed amp

Over the past couple of weeks I have tried to eliminate the HF oscillation that I have been getting from this amp. Taking my Dad's advice I removed the feedback loop.  This eliminated the problem completely.  The amp is now quite.  I am still experimenting with the two different power tubes that I have wired this amp to accomodate:  7C5 and 6V6.  Everything seems to work but I will check the voltages to see if anything is out of range.  Top photo is the complete amp minus the cab.  Second photo is the bare chassis after stamping of letters and numbers.  I also buffed with wire brush.  Bottom image is the schematic as things are at this point.  Not shown is the 7C5 socket wired in parallel with the 6V6

Chassis after letter stamping

schematic showing feedback removal

My latest acquisition.

Vibro Champ Update

The chassis prep is nearly complete. I have pots nearly all selected. I am adding push-pull pots to enable switching for tone stack and feedback loop. I've settled on a PS design with the help of the PSU design software from Duncan Amps. This allowed me to make use of a 4-part electrolytic capacitor. I had hope to use a 5.5H choke I pulled from a Knight-Kit, but an over zealous drill operator (guess who) over penetrated while drilling pot holes, and wrecked the choke. Import stuff: pilot light will be green. The 7C5 tube base had to be move from bottom mount to top mount. This 7C5 will be wired in parallel with the 6V6, which will allow "either/or" operation. Hope to have chassis fully loaded by end of August. If you get this update as an email remember to go to the blog to see full size photos.

Vibro Champ Clone

I've decided to postpone the Frankenstein amp (Conn 6020) and pursue a Vibro Champ (AA764) clone. Like the Frankenamp I have all of the parts that I need, but I believe the Vibro champ will be easier. With the other projects I have going I think it is a better fit. I have two solid state amps that will get attention soon. I will say this for the benefit of those who wanted to know how I was going to convert the Conn 6020, I am looking at the Ampeg Portoflex SB12 as a basis. As far as the Vibro Champ, I have one thing to resolve: the power supply. I have been rendering some old Knight Kits and one old Conar kit for parts. I hope to use a pre-Stancor Chicago Standard transformer and a 6X4 rectifier taken from a Knight-Kit O-scope.

Carmen Ghia Goof

It turns out that the problem I've had with this amp hasn't been a bad component but my error.  When I converted the Hammond AO-35 using the Phoenix schematic, I failed to ground a resistor that was tied to the terminal strip on the side of the chassis.  Grounding this resistor solved all of my problems.  My Dad found this problem while we were trouble-shooting this by phone.  Thanks Dad.  Click on the image to see it enlarged.

Frankenstein Amp to be "born"

It has been one year today since I last posted. Since then some caps on the Carmen Ghia have started leaking and producing awful noise. That project will be this summer. Now I am designing a "new" amp to be made from the main amp (model 6026) that came from the Conn Model 542 Minuet organ. What I hope to do with it involves adding a single preamp to drive the two power amps in parallel. The twist is that I hope to tie the two output transformers in series on the secondary side. Schematics will get worked out before November this year. I probably won't finish this until 2014.

Carmen Ghia clone Finished!

After 9 months worth of work on and off, I finally finished building a Dr. Z Carmen Ghia clone. I built it from the old Hammond AO-35 reverb amp, given to me by Ron Ashcraft back on Monday, May 12, 2008. Building the cabinet took more time, effort, and money, than did modifying the A0-35 circuit. I took lots of photos of the entire process. I will put them all out on a photo dump in the future. The amp sounds great but has more gain than I need around the house, so I've swapped the phase inverter tube from a 12AX7 to a 12AT7. The result is a little more clean headroom with a little less noise.
If you receive this blog update as an email, remember to use the link at the bottom of the email to get to the actual blog. Once there you can click on the photos and they will enlarge.

Dayton Hamvention 2012

I went to the Dayton Hamvention on Saturday. Tickets were a steep $25 at the door. My friend Brian landed a BOULEVARD PRINCE for $20. This is a tube powered PA amp from the late '50s or early '60s. As you can see in this photo I got a SHURE SM57 for $10, and a RAMSEY digital multimeter (ohms to 2M!) for another $10. I also bought a pair of 12AT7 tubes. All of these items worked for Brian and I, except for one. I bought a DIRECTV satellite box for $10 knowing it was a gamble. I plugged it in to the satellite dish and it worked, but too well. After it booted up it checked in with the intergallactic command center and then told me that it's registration had expired. In the trash it goes. If you get this update in an email, you can click on the link here and it will take you to the web site where you can enlarge the photo.

Rendering the CONN organ

I have been rendering or stripping the CONN organ, recently acquired. There is mouse crap all over the inside of this thing. The speakers are 12", not 15" as previously reported. The upper and lower keyboards are hinged. Under the lower keyboard is a circuit containing roughly 52 of these capacitors. This may be part of the tone generating circuit. I hope to learn the type of contruction for these caps.

Donor Organ #4

My Dad provided parts from a solid state Lowrey and Hammond, and Ron Ashcroft provided the AO-35 from a Hammond. Friday I retrieved a 1961 Conn model 541 "Minuet" in non-working order. This was listed in the free section of CL. Yes it is a tube job. The amplifier is actually a stereo power amp using two pairs of 7868. These amps go through two crossovers to drive two 15" speakers and a rotating assembly with a Jensen driver. I am thinking about removing this entire assembly complete. The photos show that each key is controlled by half of an 12AU7 and its own tunable transformer.

REMEMBER TO CLICK ON THE LINK BELOW TO GO TO THE BLOG, WHERE YOU CAN SEE THE PHOTOS FULL SIZE.

Champ amp now in cabinet

I finally completed the Fender Champ project. Though the joinery didn't come out like I'd hoped, it turn out well enough. The front baffle was a sliding lid from the 1969 Magnavox console I stripped a couple of years ago.





If you look at the first picture to the right you might think I was way off on centering my handle. The handle isn't centered on the length of the amp, but on the weight. You can see why in the second photo.





In the third photo you can see the aluminum HVAC tape used for RF shielding, as well as the speaker scews used for mounting. The voltage plate came from the Tektronix ocilloscope I've been stripping.


If you receive this blog update as an email, remember to use the link at the bottom of the email to get to the actual blog. Once there you can click on the photos and they will enlarge.