Tube amp #2 underway.

[Jerry]

So I've started this one as #2. Mostly out of curiosity.

I've allways built PP 6V6,6L6,EL34,6550, 807s type amps in the 20 to 200 watts class.

After reading about the large triode single ended that typicaly deliver 8 to 11 watts with 10% distortion and reatail for $2500 to $25,000 for a pair of mono blocks, I dicided to build one to see whats all the fuss is about?

There plenty of DIY builders and designers on the net. They show there amps, schimatics and discus there design preferances.

They all claim to have the best approach.

Some say the signal path should absolutly have no transformers (Futterman, some say no capacitors, some have transfomers at every gain stage and output, some have combinations of interstage transformers and RC coupling, some say all the tubes in the amp should be triode, some pentode some half & half or input only or output only, some say large amounts of neg. feedback some no feedback at all.

Well since there is no general connsences. I'm going to try alot of diferant combinations. I'll find my own listening sweet spot?

The littel amp sounds great directly from the cd player. It will most likley end up as a mid/high amp in a 2 way system.

Heres a couple pictures of the big single ended triode amp. Theres nothing under the chassis yet & I have yet to build the power supply.

I plan DC on all the heaters and inductive interstage coupling. The output is a 812a(Chinna) the first af and driver is a 6SN7. I may also try the 811 or the 211/vt4C?

Output trans is a 20 pounder.

                        JK TAS Jerry

[12AX7]

Hello Jerry!

Lookin good so far!

if I may, I'd suggest moving the input.  The weight of the cables can (at times) exceed the holding power of some rca jacks.   I've an old "Altec" 340a mono block, it's surface  mounted jack makes routing of cables a pain.  

any thoughts on a votage regulator?

I hope you inspire others!!

[oztules]

well best of luck with the power supply, hum is the only hurdle to jump  with "A" class. I don't mind tellin yer that I'm starting to feel very uncomfortable about not bringing my valve gear over here.....not to comfortable at all.

I am very happy to see you do this, as I may never get the chance to do those builds again. Keep up the posts on this please Jerry.

fingers are starting to twitch.............oztules

[drdongle]

You know guys there is a far simpler way to do what you want, buy a SPACE HEATER!

Sorry I just love to argue with the tube amp guys, especially when they go on and on about the "warmth", "transparency", "crispness", and other ill defined tube amp qualities. There have been many double blind test that showed the people who claim to have "golden ears" couldn't tell the difference between a tube or solid state amp when operated at conservative levels.

But as always to each his own.

[DanB]

I suppose it depends on the quality/cost of the solid state amp.  I've done a few such side by side tests myself with a variety of solid state stuff and there's no comparison in my opinion.  But I expect once you get into really high end solid state stuff things get better.

I love how simple a really good sounding tube amp can be - seems like a decent sounding solid state amp is very complex and very expensive.  They both have their pros and cons.  To me it seems the #1 pro of solid state stuff is cheap power (you can have lots of power for relatively low cost) and the #2 is efficiency.

Solid state amps sure make lousy heaters though... ;-)

[Jerry]

Hi Dr D.

I agree with you on the double blind test. I have a good freind who is an awsome electronic and audio engeneer.

He prefurs solid state? I've also built plenty of solid state amps. But its all in good fun.

There will never be an end to the debate but I still enjoy building and listening to the home brew stuff.

I also like building a $k amp out of my junk collection. Free even makes it sound better.LOL

As per regulation, well theres another debate. The power supply will be fairly rock solid. I like stable power supplies.

                          JK TAS Jerry

[TomW]

Nice diary, Jerry. Seems the art of using tubes has gone the route of the horse for transportation. Still a few around doing it but most would consider it a step way back. My hearing is pretty well shot from gunfire, artillery and rock concerts mixed with chainsaw noise to the point of the inability to tell subtle differences of any kind.

On to that other "positive".

All of that fancy solid state gear can be rendered useless from one large EMP or a massive solar flare. So, when [not if] that happens the only folks with functioning electronic gear will be those with tube gear. The vinyl records will likely be unaffected, too, depending on the strength of any magnetic fields, magnetic media will be trashed, CDs will be useless too unless you can build a non semiconductor laser and pickup too. Of course any event that powerful will likely cause other side effects more serious than loss of toys like stripping away the atmosphere from a solar flare.

Just had to toss that into the mix as I don't think many folks know how fragile that silicon junction is that enables most of our technology from transportation to entertainment.

Cheers.

Gloom n Doom TomW.

[oztules]

 Hi Jerry,

I have just reclimbed the mountain out the back of my place, searched for and found my digital camera on the mountain top.... full of water (left it up there weeks and weeks ago) but after a few hours toil I got it to  work in a fashion..... (have been without a camera for  several weeks now so couldn't post pics before now) so I was able at last to post a picture of my old 12ax7 preamp I built 30 something years ago. (The picture quality is less than spectacular as the lenses are still not perfectly clean and aligned .... but....

Now I thought this was pretty cool at the time, as it sported pcb construction  and was  fully enclosed to look part of the modern stereo systems of the day. Heat was not a problem as i ran the heaters low and only 180v on the plates.

It ran into Philips motional feedback boxes. so no power amps were required (built into the boxes)

Its all i have to show from the dozens and dozens (and dozens) of valve projects I have built over the earlier years (last last years of valves though).

All my "junk" was relagated to the landfill many years ago, and only this relic survived..... because I have yet to find something better..... and I like it.

I'd like to believe they have a sound of their own..... but it's probably just me.

Thanks for bringing it all back to life for us..........oztules

[inode buddha]

Bear in mind though, a lot of it depends on the environment and speaker quality/placement. Some of the most amazingly good tones I have ever heard came from a set of 4 Klipschorns, using the two rears for the "center channel". Regardless of what equipment was hooked up to them, they made most amps sound better. Of course, they also highlighted any flaws.

[12AX7]

I'm still keeping an eye...  hope this thread hasn't "snapped".