[Chops]

A couple years ago, one of my brothers bought a cheap tube amp off of eBay that some dude built. When he got it, it sucked. I can't remember exactly what all was wrong with it, but he didn't run it any longer than maybe a few hours at most, then never used it again. He ended up giving it dad.

After it sitting in my father's shop for a couple years unused, he decided to overhaul it so he can use it in his shop for his cassette decks and testing other gear. My brother pretty much gave it to him since I fixed his Baldwin tube amp for him a while back. Plus, he's been itching to build an actual amplifier for some time now.

So anyway, since this amplifier was absolute junk and a crap design and/or hack job, it was totally gutted out and redesigned from the ground up. There was so much wrong with the original crappy design of this thing, it was his only option. The guy who built this thing obviously had no clue on what he was doing.

Just to name a few things that I know of that was wrong with it... The power transformer was mounted wrong, on its end, there was a lot of hum, the solid state rectifier was all wrong and insufficient, and the B+ was way higher than it should have been. The volume pot was junk and both channels were uneven.

Now, it is a totally new amp. Solid grounding throughout, new quality volume pot, tube rectifier, proper (slightly lower) B+, all new topology, all new everything. The only thing kept in this amp is the power and output transformers and the shoddy chassis with flimsy top plate. Even the tube sockets were replaced with quality ceramic ones.

BTW, this is just the beginning. He's seriously thinking about possibly designing and building some all original designs and selling them. Who knows, it might just work. Besides, he's been building tube gear ever since he was 7 years old, and he's now 73!

Alright, enough yacking. On to the pics...










Oh, and of course, a sweet pair of minty DCM TF-350's, from my other brother...

[Ericus Rex]

Well, how does it sound???

[JCarney]

Love the volume knob on top of the chassis, instead of on the front. Easy to get to, and it just looks good up there. Nice and neat inside, your dad knows his stuff it looks like.

Thanks for sharing,
JCarney

[Chops]

Well, how does it sound???

In a word... Impressive!

It has a very smooth yet detailed sound. It's very open and spacious with ample output. In fact, it sounds more powerful than it really is (about 4.5 watts p/ch). On his equipment, it's pretty much ruler flat from 30Hz-18kHz. That's quite impressive considering those tiny output transformers. It's just a very good, clean sounding little amp, light years ahead of what it was originally.

Come to think of it, it reminds me a lot of the Cary Audio SLi-80 except possibly a little bit smoother and airier on the top end.

I can't wait to see what ole' pops has in store for us when he designs and builds his next amp truly from the ground up, including the chassis.

[Chops]

Love the volume knob on top of the chassis, instead of on the front. Easy to get to, and it just looks good up there. Nice and neat inside, your dad knows his stuff it looks like.

Thanks for sharing,
JCarney

Thanks!

Yes, he certainly does know what he's doing. Then again, he's been designing and building all sorts of equipment for the past 66 years. His first ever project when he was 7 was building a crystal radio and incorporating into a tiny integrated tube amplifier that he built from old TV parts and installed in a cigar box!... When he was 7! It was essentially a receiver! His father used to run a farm and do TV repairs as well, so there were tons of tubes and parts laying around for him to play with. He also designed and built a 2-way intercom system that ran from his father's TV shop to the house! He learned everything from his father and old RCA tube books. In fact, I have one of those original books here in our bedroom that dates back to 1946.


This amp could have been a lot neater inside if he had the proper chassis to work with and was willing to make a new top plate for optimum placement of tubes and such. He just wanted to fix this one up as cheaply as possible just to get it operational for his own needs.

When he whips up something new to actually put on the market, it'll be something special. I've seen pictures of some of the stereo gear he designed and built back in the 60's and early 70's, and it looked like professional store bought gear! I can only imagine what he's capable of now!

[Ericus Rex]

Nice!  Is the pot a hum canceller?

I have fond memories of those DCM Timeframe speakers.  My first dabble into (low) hi-end.  Unfortunately for me I couldn't walk out of the store with them as my store credit was denied!  I was only 19 at the time with very little credit history....

I also look forward to seeing his next project.

[Maritan]

I love all the equipment in the background!

Oh, yeah, and the amp looks great too.  Question: The power transformer and the output transformers seem to have the same orientation. I heard this was a no-no for noise issues? Maybe not. I'm curious to see what he cooks up next.

I'm starting to understand how a vacuum tube actually amplifies a signal, so I'm fairly confident that if I read up a little more, I can start building my own SETs. Problem though is the chassis. I have little to no experience with mechanical work and I certainly don't have the tools for it.

[Chops]

Nice!  Is the pot a hum canceller?

I have fond memories of those DCM Timeframe speakers.  My first dabble into (low) hi-end.  Unfortunately for me I couldn't walk out of the store with them as my store credit was denied!  I was only 19 at the time with very little credit history....

I also look forward to seeing his next project.

Yeah, that pot is there for controlling hum, though it's not needed, so he's going to remove it. This amp is now dead silent when there's no music playing.

Those DCM's are great speakers. They just sound "right" if you know what I mean.

[Chops]

I love all the equipment in the background!

Oh, yeah, and the amp looks great too.  Question: The power transformer and the output transformers seem to have the same orientation. I heard this was a no-no for noise issues? Maybe not. I'm curious to see what he cooks up next.

I'm starting to understand how a vacuum tube actually amplifies a signal, so I'm fairly confident that if I read up a little more, I can start building my own SETs. Problem though is the chassis. I have little to no experience with mechanical work and I certainly don't have the tools for it.

I know that placement/orientation is critical for inductors in crossovers, but not sure with power and output transformers. It would make sense though. And if you look a little closer, the power transformer's iron is actually laying horizontal while the output transformers iron is vertical. With that said, as I mentioned in the previous post, the amp runs dead silent, so no issues there.

Once you get the basic concept of tube amps down, they do seem a bit simple and easy to build, though I still wouldn't want to be alone when I powered up my very first build. Someone would need to be standing by with a fire extinguisher or the local bomb squad. LOL

[Ericus Rex]

I think the tranny config is right.  The cores are 90 deg off axis from each other. 

[poseidonsvoice]

Pretty sweet! I hope to have as much enthusiasm as your father when I reach his golden age...

Best,
Anand.

[Maritan]

I know that placement/orientation is critical for inductors in crossovers, but not sure with power and output transformers. It would make sense though. And if you look a little closer, the power transformer's iron is actually laying horizontal while the output transformers iron is vertical. With that said, as I mentioned in the previous post, the amp runs dead silent, so no issues there.

Once you get the basic concept of tube amps down, they do seem a bit simple and easy to build, though I still wouldn't want to be alone when I powered up my very first build. Someone would need to be standing by with a fire extinguisher or the local bomb squad. LOL

Obviously I wasn't paying close attention to the pictures. And yes, I would definitely be nervous about switching on my first tube amp... Have a fire extinguisher handy and switch the amp on outside the house far away from anything flammable. 

[Captainhemo]

Man,  I love  reading   stuff like this.  Your father has obviously had  a passion  for  this  most of  his life, it's great to see he  still really  enjoys it 
Thanks for sharing  Chops, looking  forward to reding about his next project

-jay