Tubelab Simple P-P

[tubelab.com]

And have you tried it with 6CW5?

Yes, I have a box full of 6CW5's from all of those HP audio oscillators that I parted out. They work fine, but must be operated at a lower B+ voltage than a 6BQ5/EL84. They seem to prefer a 3K ohm OPT too. I have also used some 7189A's that can be cranked harder than an EL84. I will have data with all 3 tube types in the manual.

place my order, collect all the parts, and get building!

I am still finalizing the parts list. I haven't finished the testing with all 3 tube types. It may be possible that some resistor values will depend on which tube is used.

That universal driver board also sounds great. I would think that power supplies and output tubes could pretty easily be wired point to point, even by beginners.

The output tubes, yes. The power supply requires two positive voltages and a negative voltage. All of my amp development is done using regulated bench supplies, although none of them are in particularly great shape. One of the reasons for the test amp that I just built is to find out if regulation is required or advantageous for any of the supplies, and what voltages work best for a given tube and load impedance.

If anyone wants to balk at $35.00 for a well researched printed circuit board that is a proven design, they need to design their own amplifiers.

They don't even need to design their own. My schematics are on the web site, and people have built their own. I have no problem with that. There are still people that believe a PC board will mysteriously suck the life out of the sound. If they want, and are capable of building one of my designs PTP, go for it. It can be done with the Simple SE. There are at least two builders that have done a Tubelab SE using PTP construction. Heck, I wouldn't even try that myself.

All of the funds collected from selling PC boards goes into paying for the experiments that I do, and the development of more stuff, including more boards. I have not done a good job getting all of my experiments posted on the web site but most of them have been posted on the forum.

It is interesting that one of the whiners that refused to pay $35 for "something that he could do himself" had the nerve to email me a few months later complaining that the design was a POS since his amp hummed. I didn't answer him.

I have a talent for smoking anything solid state

If I saved all of the sand based life forms that I have killed over the years I could easilly fill a garbage can. Any SS device connected directly to the power lines or a car battery can really go bang. Often there is only a black stain on the PC board where a chip or mosfet used to be.

[Vargas]

I usually keep pretty quiet, but I must say George, I love your work and all you have done and I cant wait for the P-P boards to go on sale! I myself would love to try something with some screen drive, some day.

It is interesting that one of the whiners that refused to pay $35 for "something that he could do himself" had the nerve to email me a few months later complaining that the design was a POS since his amp hummed. I didn't answer him.

Some people are NEVER happy no matter what! Please dont let this kind of crap discourage you in any way because most of us like your work and the efforts you have put in, especially with all what is going on in your life right now! Thanks

[Curly Woods]

Originally Posted by Vargas

Some people are NEVER happy no matter what! Please dont let this kind of crap discourage you in any way because most of us like your work and the efforts you have put in, especially with all what is going on in your life right now! Thanks

As my Dad was fond of saying about folks that liked to bitch all the time "They would bitch I they were hung with a new rope". Rest well old fella, you are missed by many :-)

[tubelab.com]

Please dont let this kind of crap discourage you in any way because most of us like your work and the efforts you have put in, especially with all what is going on in your life right now!

It doesn't, I posted this because it was the worst case of whining that I have received. In reality most (99%) of the email that I get is very positive. I can't possibly have the time to answer it all, but I try. Last night I got home late and spent the entire evening answering email even though there is a half finished Simple P-P board on my bench calling my name. I tried to explain the reason that a board cost $35 to him in response to his first email. I even mentioned that I spend considerable effort chasing hum so that the builder won't have to. Then when I got his second email, I just laughed.

My life has returned to almost normal after nearly 2 years of no amp building and very little experimentation. There are rumors of another round of layoffs at work. If I get past that one, things will be OK and all of the stuff that I outlined previously will happen.

[Coreyk78]

This thread is good news! I love my Simple SE and have been waiting for the Simple PP. I was thinking of putting together a Buffalo 32 DAC after I finish building my Aleph-J. However, I think the DAC may be getting pushed back so I can build a simple PP instead, hehe.
Thanks for all your had work George, and if anything, $35 is too cheap for one of these boards.

[SigloOne]

How are things going with populating the test boards? Just curious.

Hope everyone's weekend is going well!

[Doc Jr 8156]

Hello George,
Stop worrying about the complainers, they will never be satisfied. $35 for a well engineer board is a bargain indeed. Your effort and support for your products speaks for themselves. I just finished my 3rd Tubelab amp and very happy with them. It was a dream of mine to own an EL-84 based amp. I tried different Scotts but not satisfied with their sonic coloration and sold them all. Your PP amp is the ticket I reckon. Godspeed, Sir.

John Revilla M.D.

[tubelab.com]

Well, Sherri got back into town yesterday after being gone 3 weeks. We had lots of stuff to do, but I still managed to "light one up". I can see several configurations for this amp, and like the Simple SE, I expect that most people will want the biggest power transformer to get the most output power. There have been several requests for a minimalist configuration, the best amp for the absolute least money. Since that was the first set of transformers that I came up with when I started scrounging, that is what I built.

I have an Allied 6K56VG power transformer and two Edcor XPP10-8-8K OPT's. The output tubes are some Russian 6P14P tubes that were $3.50 each on Ebay including shipping from the Ukraine. I have not had any time to optimize anything, so the board is as built. I am getting 10 WPC in UL mode at 3% distortion. Triode or pentode have not been tested yet. I am drawing a bit too much B+ current from the transformer, but it has been running at full power for 2 hours. The power transformer is cooler than the one in my Simple SE and the hot smell turned out to be the dummy load resistors. I found that many 8BQ5's work just fine since Hammond transformers supply nearly 7 volts on their filaments. These can often be found cheap.

I plan to do some more testing with different tube / transformer combinations. I don't think that these tubes can deal with high voltages, but I have some 7189A's to try. I will also test 6CW5's, they run at much lower voltages, but can be made to crank out some power too.

[Ty_Bower]

What's the driver tube on these guys? 12AT7? Is the schematic up on your site?

I'm intrigued that you opted to use a choke in the power supply on these. I'd assume that given the "absolute least money" directive, it would be the first thing to go. Sure, on a single ended amp it makes a big difference, but in push/pull doesn't a lot of the residual PSU hum tend to cancel out in the finals?

[tubelab.com]

The schematic, or any new information related to the Simple P-P has not been posted yet. For now all that I have is the Eagle schematic which only shows the board mounted components. The driver tube is a 12AT7.

There is a resistor on the board with the two terminals to use a choke if you want. When I saw that a 150 ohm resistor was costing me 30 volts, I dug up a cheap choke with a 50 ohm DCR. I picked up 1 watt of power.

I wired it up in pentode mode, and applied about 5db of feedback. power was 12 WPC. Distortion at 1W is 0.17%. Power output below 50Hz was limited by transformer saturation.

I connected a CD player and speakers. It sounds very good, some saturation was heard on Money for Nothing, but if you stayed away from the saturation, the bass wag pretty good.

The sound quality was good, and easy to listen to. It will not strike fear ino the 75WPC all triode monster that I have been working on.