Clone your own Bada PH12!

[Guest sacd lover]

You wouldn't believe the PM conversations we had here when he first arrived. It was wonderful.

Oh wait, or have you been peeking in my PM boxes?

You should post them. People need to know what a nut this guy is.

[humanflyz]

@cotdt:

dude you need it to tone it a down a bit. I remember your early Head-Fi posts on the K701s made you seem like a troll, and now you've changed your tune to sing the praises of the D2000s just as authoritatively, at least that's how I read your posts. Maybe you didn't mean them to sound that way, but perhaps you should either a) qualify your statements or don't post in every single thread that has something remotely to do with whatever equipment you have. After all, if I posted in every single thread there is about the stuff I own, I'd be doing nothing else.

[deepak]

I think it is a little funny cotdt praised the K701 so much, and I did get a laugh out of you pissing davesrose and piccolonamek off so much. They're good mid-fi headphones nothing more.

[cotdt]

I'm trying to make sense of the Doge circuit, but either it's too early in the morning or something's really weird. It looks like a cathode-follower input to a common-cathode gain stage which then feeds the trioded output tube.

Other than dropping gain, I can't figure out a reason for a cathode-follower input, and the 330k resistor puzzles me as well. It's just not making sense to me, I don't know if it's some brilliant concept which is way over my head or an amateur hackjob.

i don't understand it either, but the amp sounds good to me! I've been told the 330k between the anode of the output tube and the anode of the driver tube makes the whole circuit behave in a different way than usual. The driver acts as a current amplifier, while the output tube acts as a current/voltage converter.

[postjack]

how do you people have time to read head-fi so much. i'm too busy waiting for people here to say something.

[postjack]

something.

k, going to go catch up on all the bullshit in the HF amp forum, see you all in a few days.

[mirumu]

I think it is a little funny cotdt praised the K701 so much, and I did get a laugh out of you pissing davesrose and piccolonamek off so much. They're good mid-fi headphones nothing more.

I always found that funny too. In response they'd always call cotdt a troll which made it extra amusing given how outspoken they both are.

As to Mr. Wells, I'd barely been at head-fi five minutes before he PM'd me trying to sell me "the best" tubes for my Xiang Sheng amp which to me didn't appear to be anything especially amazing. I don't know much about the guy to comment otherwise but he appears to not believe there's such a thing as personal taste given many of his comments.

[hYdrociTy]

SACDlover picked an inept liar in cotdt.

[Nanoha]

"SACDlover picked an inept liar in cotdt." - drarthurwells

Oh, lols. Major lol.

[cotdt]

your arguments are the infantile remarks of a blathering fool

i thought forums were a place to offer opinions and debates, but instead it is more like Jerry Springer.

[postjack]

not sure if those remarks are quoted from HF, but if they are the good doctor is cruisin' for a bannin'.

[Dusty Chalk]

Oh please oh please oh please oh please oh please...

[Guest sacd lover]

I'm trying to make sense of the Doge circuit, but either it's too early in the morning or something's really weird. It looks like a cathode-follower input to a common-cathode gain stage which then feeds the trioded output tube.

Other than dropping gain, I can't figure out a reason for a cathode-follower input, and the 330k resistor puzzles me as well. It's just not making sense to me, I don't know if it's some brilliant concept which is way over my head or an amateur hackjob.

Any idea of what is the best solution to alter the 6210 circuit for the best performance?

I saw this post on head-fi by Roam ....

http://www.head-fi.org/forums/showpost.php?p=2960986&postcount=341

[Nanoha]

Any idea of what is the best solution to alter the 6210 circuit for the best performance?

I saw this post on head-fi by Roam ....

http://www.head-fi.org/forums/showpost.php?p=2960986&postcount=341

By the way, I've talked to Roam several times in the past. He is an extremely knowledgeable person when it comes to tube amplifiers.

[bhd812]

I always found that funny too. In response they'd always call cotdt a troll which made it extra amusing given how outspoken they both are.

As to Mr. Wells, I'd barely been at head-fi five minutes before he PM'd me trying to sell me "the best" tubes for my Xiang Sheng amp which to me didn't appear to be anything especially amazing. I don't know much about the guy to comment otherwise but he appears to not believe there's such a thing as personal taste given many of his comments.

you guys do know that pm's sent trying to sell something is not looked highly..maybe a ban can be placed..just letting you know

[n_maher]

Any idea of what is the best solution to alter the 6210 circuit for the best performance?

Why would you want to change it? Dr. Shill says it has "the strongest bass of any HP amp."

[cotdt]

For the record, the harmonic distortion I measured on the Doge 6210 is extremely low for a SET amp at 0.2% and the frequency response is ruler flat throughout the audible range, even with negative feedback disabled.

The Doge 6210 circuit may look strange, but the sound is what matters. I'm going to do a shootout against the Woo6 in a couple days. I do have other 12A*7/EL84 circuits on hand that I may try, and probably will given that I acquired some NOS 5751s as singles so using a single driver tube to drive both channels is appealing to me. Look for impressions from myself and Aaron on:

Doge 6210 (lightly modded) versus Woo6 (amp shootout)

Zapfiltered AD1852 versus Ori AD1852 (both inside a Zhaolu 2.5, DAC shootout)

Denon D2000 versus ATH-AD2000 (headphone shootout)

and also upcoming impressions on the balanced Beta22.

[cotdt]

Why would you want to change it? Dr. Shill says it has "the strongest bass of any HP amp."

who is Dr. Shill? got any link? the stock Doge has rather average bass in my opinion. only when i used lower gain driver tubes like 5751 and lowered the feedback did i get good bass.

[Nanoha]

who is Dr. Shill? got any link? the stock Doge has rather average bass in my opinion. only when i used lower gain driver tubes like 5751 and lowered the feedback did i get good bass.

Dr. Shill is arthurwells.

[cotdt]

Dr. Shill is arthurwells.

I see... but I don't think he is a doctor. He is much too unstable.

[aerius]

Any idea of what is the best solution to alter the 6210 circuit for the best performance?

My first move would be to dump the 12AX7 tube, and then choose from either a 6SL7, 6SN7, ECC40, or 5687 depending on how much gain is needed. Next would be to put the gain stage first and then the cathode-follower, or dump the cathode-follower altogether. I still don't know what that 330k resistor does so we'll leave it for now, but removing it might be an option. All those 10k grid-stopper resistors can likely be dumped as well, with a good wiring layout you don't need them. Then you can play with fun stuff like LED biasing on the tubes and an ultrapath capacitor between the B+ end of the transformer and the cathode of the EL84.

[PFKMan23]

You want my frank and honest answer? Because people don't know any better. Because 95% of the "designers" in audio are amateur hacks masquerading as "audio engineers". These people, and 99% of consumers, would not know good circuit design if they were beaten over the head with it.

This is only true of competant designs.

That's the biggest load of crap I've heard in a long time. I have the schematics for the Bada PH12, it's filled with nearly as much unadulterated stupid as the Doge, and furthermore I have a good idea of the design process behind it.

Some moron looked at a circuit for a 6DJ8/6922 hybrid amp and thought "6SN7's are in style, let's put 6SN7 tubes in it", and proceeded to do just that without altering any of the component values. That explains why the plate loads on the 6SN7 cascode are only 10k, which is far too low for a 6SN7 but in the right ballpark for a 6992. It also explains the grid-stop resistors which are completely unnecessary for a 6SN7, but may be needed for a 6922. The only reason to have them with a 6SN7 is as insurance against sloppy incompetant layout.

Grid-stoppers are often needed for high-gain higher transconductance tubes such as the 6922 or WE437A to prevent oscillation, but audio tubes such as the 12AX7 & 6SN7 are far more stable than the high-performance tubes which I named above, and do not require grid-stoppers. It takes a lot of pure concentrated stupid to make a 6SN7 oscillate, and if one is putting grid-stoppers on a 6SN7 it indicates one of two things: a circuit for another tube was ripped off without understanding it, or the person was an incompetant moron who knows nothing about circuit design. Come to think of it, I don't see much difference between the two.

The circuit for the PH12, for those who want to see it can be found here.

http://www.head-fi.org/forums/showpost.php?p=2963571&postcount=357

Art just got reamed....

[n_maher]

I like this Roam.

I have the schematics for the Raptor, the fact that one can even get sound out of it is a testament to how forgiving tubes are of inept circuit designs.

[en480c4]

Have I been out of the loop, or is it also news that the good doctor's avatar is now preceeded by this:

drarthurwells

Headphoneus Supremus:

Member of the Trade:

Cattylink

[NotoriousBIG_PJ]

I never noticed this Roam guy before. He posts like he is Aerius's twinner, and every post is gold.

Biggie.