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Jeffrey D. Medwin

Daniel's 6SN7-2A3 SE tube amp, a LESSON LEARNED

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I just saw this photo, and almost fell out of my chair .  People scoff at me, when I advise them to eliminate all tie wraps. 

 

                                                                            This amp "takes the cake" folks !!!

 

This is Daniel's ( who asked for assistance in Les's Softtone 300B amp thread )  2A3 amp, the below-deck photo he just sent me :

 

Recall, I explained wires have FIELDS around them, and it is best to keep them physically separated, and never ever bundle wires with tie - wraps.  Here we GO !!

 

1708110796_Daniels2A3B.jpg.24a6105d750903ca21c38b48b13c634d.jpg

 

NUMBER ONE :  Ties the lowest signal level in the whole amp, the input signal from the RCA jacks, to the SPEAKER OUTPUT transformer's secondary  / speaker leads, .....tightly !!  

 

NUMBER TWO :  Ties the output of the 300B tube ( green wire ) , driving the primary of the Output transformer, to the Input leads .

 

NUMBER THREE :  Is beautiful, it tie wraps 120 VAC  house wiring to BOTH speaker leads, on one channel.  Ohh - my goodness.

 

NUMBER FOUR :   Again ties leads  to the 120 VAC house wiring, with 120 VAC needlessly leading to a ( wrongly positioned on the front panel ) ON-OFF AC switch.

 

NUMBER FIVE :  Ties the output of the 300B tube ( green wire) to the 120 VAC house wiring .   Holy smokes. 

 

                                                                                                  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 

 

 

Daniel, your immediate job is, with diagonal cutters, CAREFULLY, neatly cut-off each and every one of those tie wraps, and THROW THEM AWAY !!!

 

Secondly,  separate all the wires, for minimal field interaction, so that they do not touch each other.  INPUT wires, left and right channel, need to be as far apart as you can go, and THINK and place wires three dimensionally. 1/8th inch apart minimum, more is better. 

 

Third, LISTEN to that, a zero money cost modification of your Chinese amp.

 

Fourth, please REPORT BACK to ALL,  if you heard any difference on your La Scalas, and if so, what !!    A subjective report back. Be very very careful of Maynard's " expectation bias" which will occur after reading this post of mine, and be honest with yourself, and us all.

 

I LIKE the coupling caps.  Mundorf 0.1s.  I use Mundorf Supreme Silver and Oils  in 0.15 uF  sometimes, as a part of multiple film cap bypassing. 

 

I will answer your PM, after you do this, first, and report back whats happening on your La Scalas.   Fair enough ? !!! 

 

Don't nick the wires or stress any solder joints.  Just be careful. 

 

Best wishes,

 

 

Jeff 

 

 

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8 hours ago, Jeffrey D. Medwin said:

 

Daniel, your immediate job is, with diagonal cutters, CAREFULLY, neatly cut off each and every one of those tie wraps, and THROW THEM AWAY !!!

 

Secondly,  separate all the wires, for minimal field interaction, so that they do not touch each other.  INPUT wires, left and right channel, need to be as far apart as you can go, and THINK three dimensionally. 1/8th inch apart minimum, more is better. 

 

Third, LISTEN to that, a zero money cost modification of your Chinese amp.

 

Fourth, please REPORT BACK to ALL,  if you heard any difference on your La Scalas, and if so, what !!    A subjective report back. Be very very careful of Maynard's " expectation bias" which will occur after reading this post of mine, and be honest with yourself, and us all.

 

I LIKE the coupling caps.  Mundorf 0.1s.  I use Mundorf Supreme Silver and Oils  in 0.15 uF  sometimes, as a part of multiple film cap bypassing. 

 

I will answer your PM, after you do this, first, and report back whats happening on your La Scalas.   Fair enough ? !!! 

 

Don't nick the wires or stress the solder joints.  Just be careful.

 

Best wishes,

 

 

Jeff 

 

 

 

Thanks again for replying, I brought all of this upon myself! Cutting the tie wraps shouldn't be a problem, though I'll likely only get around to doing it sometime next week.

 

So once I cut the tie warps and separate the wires, am I leaving them "floating" around?

 

The coupling caps are Mundorf Supreme Silver in Oils.

 

I'll do my best to report on any notable changes, though I can attest to the power of expectation bias. Also I haven't got the best auditory memory recall.

 

6 hours ago, mike stehr said:

Was that amplifier purchased through eBay or Amazon?

 

The amp is a Fluxion B-6TK and contrary to what Jeff said, is made here in Canada and sold directly from the builder. His background is in EE in South Korea and he claims to build circuits just as he learned at university in the 80s. He is clearly of the "test-bench" and "measurements" camp, which I'm grateful for because I know that the amp "measures" well, at least for a SET. He is very active on youtube and has several amp offerings. The build quality is pretty swell for the price (nice thick aluminium chassis, custom made/wound transformers, simple circuit, PP wiring).

 

Daniel

 

 

 

 

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Daniel, 

 

You asked :

 

 

"  So once I cut the tie warps and separate the wires, am I leaving them "floating" around?   "

 

 

YES, absolutely.    a) Float them three-dimensionally below deck, so they don't touch each other.  Its perfectly OK to have below-deck wiring appear as a "rats nest"

                                b) Where wires do cross, the least field interference occurs if the crossing wires are at 90 degrees to each other.

 

This thread is now even better when you tell us the Manufacturer's background, and its a university - trained Canadian in his 60's.  Any idea his major ???

 

This thread and story would be absolutely " PERFECT ." .......... if he studied, and maybe even graduated, in E.E. 

 

Positive aspects of his design schematic and implementation photo, lead me to believe that. 

 

This 2A3 amp of Daniel's has a certain amount of inherent unrealized potential IMHO !!   

 

Lets see what Daniel honestly hears, with the first simple mod suggestion.  Will it help his complaint to me, of a " too forward midrange "???

 

Jeffrey Medwin

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47 minutes ago, Ray_pierrewit said:

I'll do my best to report on any notable changes, though I can attest to the power of expectation bias.

It's good that you recognize this.  It's rampant in Jeffs threads.

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11 minutes ago, CECAA850 said:

It's good that you recognize this.  It's rampant in Jeffs threads.

 

 

LOL,.............. Its even better that I brought it up, and warned Daniel,  ........first !

 

Tell me Carl, what do you think of those tie wraps, and my suggestions?  What would you do, if you owned the amp ??

 

Jeff 

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9 minutes ago, Jeffrey D. Medwin said:

Tell me Carl, what do you think of those tie wraps, and my suggestions? 

I find most of your suggestions hilarious.  I love the ones about golf balls and bricks.  It's what keeps me coming back.  Carry on.

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16 minutes ago, Jeffrey D. Medwin said:

What would you do, if you owned the amp ??

Ask Maynard for advice.

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17 minutes ago, CECAA850 said:

Ask Maynard for advice.

 

 

You have a good mind !!  Very nice Carl.  

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43 minutes ago, richieb said:

} A mind is a terrible thing to waste — 👨‍🎓

 

 

As is our precious and limited time, posting on Audio Forums.

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1 hour ago, Jeffrey D. Medwin said:

This thread is now even better when you tell us the Manufacturer's background, and its a university - trained Canadian in his 60's.  Any idea his major ???

 

This thread and story would be absolutely " PERFECT ." .......... if he studied, and maybe even graduated, in E.E. 

 

Positive aspects of his design schematic and implementation photo, lead me to believe that. 

 

This 2A3 amp of Daniel's has a certain amount of inherent unrealized potential IMHO !!   

 

Yes, the builder's background is in EE, from a South Korean University in the 80s. He worked, I believe, at some state broadcasting corporation maintaining and fixing electronics until he moved to Canada where he builds these amps as a retirement project.

 

Just to be clear, I didn't complain about the "too forward midrange" quite in those terms. I first noted the qualities of the amp, great separation, nice tone saturation, and bass texture. If I had anything to complain about, I find the midrange a little more forward than previous amps. I'm coming from a Scott 299B, which to my ears and memory, sounded great if a little soft. The 2A3 is totally silent, even with my ears glued to the speakers, and I find that it has more "jump" than the Scott, a little more dynamic. The Scott had more LF extension, but only because I always had the loudness switch engaged. I will shortly be addressing the LF with a sub or two of the fitzmaurice breed.

 

I can't see any downside to removing the tie wraps and separating the wires, it's true that some important weak signals are in very close proximity to other wires. I can't say whether or not stray fields are enough to alter the signal, but am willing to give it an honest go.

 

1 hour ago, CECAA850 said:

Ask Maynard for advice.

 

If Maynard is interested in commenting I'd gladly send him the schematic and be open to his circuit critic. I have much respect for both him and Jeff.

 

Daniel

 

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1 hour ago, richieb said:

} A mind is a terrible thing to waste — 👨‍🎓

But once it's wasted it's not so bad.

  • Haha 3

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21 minutes ago, Jeffrey D. Medwin said:

 

 

As is our precious and limited time, posting on Audio Forums.


} Now That is hard to argue —

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My first priority is to "clean up" the amp's fixed negative bias supply, simply, because it is ON the grid of the 2A3, and is " mixed " with the entire audio signal.  Not enough thinking went into its design.  It must be pristine !! 

 

  

  1193326673_DECENTSCHEMATICedit4.jpg.c9c28b531c47d8e91a1ad752050b70ed.jpg

   

 

 

 

 

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Designer: Young un? is that how you pronounce his(her) name?:)

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3 hours ago, richieb said:

} A mind is a terrible thing to waste — 👨‍🎓

A waist is a terrible thing to mind. Especially as we get older!

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"15uF FILM capacitors. (C1,2 & C3)"

 

Are you sure you want to replace a 0.1uF coupling capacitor with a 15uF cap?

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19 hours ago, mike stehr said:

"15uF FILM capacitors. (C1,2 & C3)"

 

Are you sure you want to replace a 0.1uF coupling capacitor with a 15uF cap?

 

 

Good Mike !!

 

No !! When I mentioned C1,C2,C3, they were my own NEW designations, specifically for re-configuring that original inadequate / minimalist  negative bias supply for the 2A3s' grids. 

 

The new designations were meant to have no association with the Cs in the existing schematic. It would replace the box outlined in heavy RED.   I apologize if it was confusing, but your post and question, and my answer,  may help others. 

 

Actually, Daniel's particular amp has 0.1 uF Mundorf Supreme Silver Oils in it.  Its the very best part in the entire amp !! 

 

Who put that in there ??  It amazes me.

 

I'd use that part, IF I had to couple with a cap.

 

Jeff 

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