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"favorite" outputs for Simple P/P?

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I

Ian444

Member
Joined 2008
George, speaking of favorite output tubes, have there been any, or many, requests for a 6V6 Simple PP? There doesn't seem to be many 6V6 projects around, Poindexters musical machine is the only one that comes to mind. It does look like the current circuit would easily accomodate 6V6, except for the octal sockets for the output tubes.
 
Tubelab_com

Tubelab_com

Member
Joined 2005
tubelab.com
and yours is much easier to read.
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I like his better too. If Ian agrees I can put it on my website, make it a sticky here, or both.

have there been any, or many, requests for a 6V6 Simple PP?
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When I decided to do the simple P-P I asked for suggestions. There was very little interest in a 6V6 based amp. The requests were about evenly split between an EL84 based amp making about 15 WPC and an octal tubed amp in the 35 to 50 WPC. Putting 5 octal tubes plus driver circuitry on one PC board with reasonable spacing makes for a rather large board. Too large for economical manufacture.

The plan was to do the Simple P-P since it was highly requested, and then follow up with the octal amp. The Simple P-P boards are not selling well and sales of the other boards have dwindled down to 1 or 2 a week. I have friends in similar businesses (non audio electronics boards and kits) and they report similar situations. The worldwide parts shortages and crummy economy are likely to blame.

I have several versions of octal P-P amps breadboarded. All versions use at least two PC boards. The most likely solution uses 3 boards, one for each channel and one for the power supply. The 6V6 would work in any of these designs as it does in the Simple SE. Different transformers choices are required though.
 
I

Ian444

Member
Joined 2008
Fair enough, I was doing some experimenting with 6V6 hence the question. Shame about the world economy, seems to put a damper on all things good ;)

Regarding the schematic, feel free to use it any way you see fit. You can remove my name if you want, I only put it there so people would know its not a genuine approved schematic. I could also do versions showing triode and pentode mode wiring if you would like, it would take very little time to do that.
 
Tubelab_com

Tubelab_com

Member
Joined 2005
tubelab.com
Regarding the schematic, feel free to use it any way you see fit. You can remove my name if you want, I only put it there so people would know its not a genuine approved schematic.
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I will leave it as is. You made it, you deserve the credit. I have been stuck at work lately until late every evening, so I haven't had the time to even catch up on email. The place where I work restated their "use of company property" policy. It is now stated that any activity promoting a personal business is prohibited. Since Sherri lost her job two years ago, I need to hang on to mine and they are still laying people off.

I could also do versions showing triode and pentode mode wiring if you would like, it would take very little time to do that.
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I have been asked for a complete schematic, and I have been referring people to your post. Schematics for the triode and pentode options would be useful.

Fair enough, I was doing some experimenting with 6V6 hence the question
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I know that you are familliar with the conversion of the Simple SE board to P-P thread. The thread starter now states that the 6V6 tube is his favorite tube in that amp. If you want to explore that route I can send you a couple of boards to play with.

I don't think anyone mentioned "El Cheapo".
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There are lots of schematics floating around that will work with the 6V6. Most schematics for 6L6 type amps will work for the 6V6 with power and output transformer changes.

The Simple SE was a big hit (I have sold over 100 boards) because it is SIMPLE. It doesn't take much thinking to build it. It is a good "first build". It is not too different from other SE amps that have become quite popular. The Abdellah design is one. The Simple P-P is not too different from the RLD or the Bevois Valley amp either.

I see someone currently trying to put together a kit based on the Abdellah design over in the "Tubes" forum. It is the right time of year since more people in amps in the winter, but I think this might be the wrong year to try this.

I found that many people want to build their own chassis too. If you look at all of the pictures of my amps you will find them stuffed into $10 cake pans, and you will find $500 custom made chassis. You will find them with $30 Edcor OPT's and megabuck Tamura's.
 
I

Ian444

Member
Joined 2008
Here's the schems, if you want any alterations done just let me know:

http://i198.photobucket.com/albums/aa160/birdy81260/SimplePPschemTriode.gif

http://i198.photobucket.com/albums/aa160/birdy81260/SimplePPschemPentode.gif

http://i198.photobucket.com/albums/aa160/birdy81260/SimplePPschemUL.gif

You are too generous offering some boards, thank you, but I already have a couple of experiments/projects running. You are right, the Simple SE x 2 would be the way to go, and a single PCB with 4 or 5 octal sockets gets too big. I did fit some 6V6 to an amp that was previously 6L6, and this is my latest crude experiment, however, the Simple PP still rules in my house. It does seem though from my diminutive experience that fixed bias (or LED's instead of cathode resistors) is the silver bullet for small PP amps, as you have mentioned/hinted at a couple of times. It also takes away the "simple" part, so I understand why it's not standard. Anyway, I'm getting off-topic...
 
I

Ian444

Member
Joined 2008
Yep, that's right, I changed the four screen resistors from 100R to 820R to clean up the sound when not using global feedback. I found 1K5 too much and 470R not enough. It may be different with your dual-driver speakers compared to my 4 ohm single driver speakers, I don't really know. Definitely worth trying though!
 
Tubelab_com

Tubelab_com

Member
Joined 2005
tubelab.com
It may be different with your dual-driver speakers compared to my 4 ohm single driver speakers, I don't really know. Definitely worth trying though!
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Different tubes respond differently too. I find that on my old Sylvanias the measured distortion goes up as I increase the resistor value but the sound improves, up to a point (about 470 ohms). At 390 ohms there is audible loss of punch on transients with loud music. All tests are in pentode mode with GNFB on low efficiency speakers. The good speakers aren't done yet.
 
C

chrisb

Member
Joined 2002
tubelab.com said:
Different tubes respond differently too. I find that on my old Sylvanias the measured distortion goes up as I increase the resistor value but the sound improves, up to a point (about 470 ohms). At 390 ohms there is audible loss of punch on transients with loud music. All tests are in pentode mode with GNFB on low efficiency speakers. The good speakers aren't done yet.
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Well, FWIW this puppy will be running 6P14P-EV - and to start in pentode with no feedback and 820R on screens, speakers will be mid efficiency dual Mark Audio EL70s. Hopefully bench tested in the next day or so and making no smoke, just music at home by weekend.

BTW, thanks to y'all for the suggestions - this is almost as much fun as my early days on the Bottlehead and old Decware forum
 
M

motosapien

Member
Joined 2010
Paid Member
chrisb said:
Well, FWIW this puppy will be running 6P14P-EV - and to start in pentode with no feedback and 820R on screens, speakers will be mid efficiency dual Mark Audio EL70s. Hopefully bench tested in the next day or so and making no smoke, just music at home by weekend.

BTW, thanks to y'all for the suggestions - this is almost as much fun as my early days on the Bottlehead and old Decware forum
Click to expand...

What type of speaker did you build?
 
C

chrisb

Member
Joined 2002
motosapien said:
What type of speaker did you build?
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rather a few (mostly Fostex and Mark Audio drivers presently)

this particular amp will be used with the ones on the left - dual Mark Audio/CSS EL70 paper cones with polka dots
 

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C

chrisb

Member
Joined 2002
okay dokay - y'all was patient over the past couple of weeks or so it's probably time to post my initial impression

system= MacBook Pro Airplay / Airport Express Toslink / Citypulse DAC / Simple PP / Castle Microtower CSS EL70

Sovtek 5AR4 / NOS Sylvania 12AT7 / 6P15P-EV / pentode (with feedback) + a "little" help from Daniel = :)

input sensitivity is lower than the CCS loaded LTP in the El Cheapo variant, but tons more power, dynamic snap and low end "authority" - those 4" paper cones never sounded so big

too good to take out of the system for tweakage

nah, who'm I trying to kid - but just where to start :confused:

George, et al - thanks
 
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