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Offline ebag4

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Reply #15 on: May 22, 2011, 07:13:31 AM
I have my chassis components mounted and am currently wiring everything.  I have a question concerning the wiring from the IEC to the switch and to the power transformer.  Is there any benefit to using a larger conductr here?  If so, does it have to be overall shielded or will twisted the conductors eliminate the electrical noise?

Thanks,
Ed

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Offline Paul Joppa

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Reply #16 on: May 22, 2011, 02:10:01 PM
Twisting reduces magnetic fields. Shielding reduces electric fields.

Noise on the power line is going to be high frequency, so it will radiate into nearby circuitry by capacitive coupling, i.e. electric fields, and the shielding is important. A magnetic field is generated by the 60-Hz current in the wires, and will mostly induce hum by magnetic coupling - hence the twisting is also important but for a different noise mechanism.

Paul Joppa

Offline ebag4

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Reply #17 on: May 22, 2011, 02:43:29 PM
Quote from: Paul Joppa on May 22, 2011, 02:10:01 PM
Twisting reduces magnetic fields. Shielding reduces electric fields.

Noise on the power line is going to be high frequency, so it will radiate into nearby circuitry by capacitive coupling, i.e. electric fields, and the shielding is important. A magnetic field is generated by the 60-Hz current in the wires, and will mostly induce hum by magnetic coupling - hence the twisting is also important but for a different noise mechanism.
Thanks for the reply Paul.  OK, so stay with a shielded cable for the AC input to the amp, do you believe increasing the size of the conductors to the switch and power transformer would be a benefit or are the lengths so short it just isn't an issue?

Other than my humpots which i believe may be on backorder the wiring is complete, now on to the base!!

The kit is basically stock.  I have used Azuma tube sockets instead of the stock units, since I did not use a volume control I have added a 100K resistor across each input, and I used a couple of 2.2 uF Obbligato caps I had instead of the stock 3.3 uF Solens that came with the kit.

Best,
Ed

GO CARDS!!!

Offline Paul Joppa

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Reply #18 on: May 22, 2011, 04:46:59 PM
The wire has more than enough current carrying capacity, and its resistance is a tiny fraction of  the primary winding DC resistance, so there is absolutely no known technical reason a fatter wire would have any audible effect.

Of course, there are always effects unconnected to known technical reasons. Whether they are because of mass hysteria, or unknown technical effects, or something else we've never thought of, is unknown and unknowable. So I hardly ever say "never".  :^)

Paul Joppa

Offline ebag4

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Reply #19 on: May 23, 2011, 02:12:58 AM
Quote from: Paul Joppa on May 22, 2011, 04:46:59 PM
The wire has more than enough current carrying capacity, and its resistance is a tiny fraction of  the primary winding DC resistance, so there is absolutely no known technical reason a fatter wire would have any audible effect.

Of course, there are always effects unconnected to known technical reasons. Whether they are because of mass hysteria, or unknown technical effects, or something else we've never thought of, is unknown and unknowable. So I hardly ever say "never".  :^)

Thanks Paul, I'll stick with the known factors for now.  Much appreciated.

Ed

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Offline ebag4

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Reply #20 on: May 25, 2011, 10:57:34 AM
My base is not finshed but I got the Stereomour up and running today.  All the measurements were right on with the exception of the 230VDC reading which read consistantly low across the board.  A quick call to Dan "Doc Bottlehead" and he told me they have seen this here and there and that it appears to be due to differences amoungst 12AT7 tubes, not an issue.  So I fired it up and out came music!

This is a great piece of kit, the instructions are outstanding!

A big thanks to Doc, Eileen and Paul Joppa.  Thanks to Jim Rebman and Inferno (John) for making their recommendations.

More to come as I complete the base and let the unit burn in a bit.

Best,
Ed

GO CARDS!!!

Offline Jim R.

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Reply #21 on: May 25, 2011, 11:10:49 AM
Ed,

Congrats!  Can't wait until you get some time on it and can give us some more impressions.

-- Jim

Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline InfernoSTi

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Reply #22 on: May 25, 2011, 05:17:47 PM
Wonderful, Ed!  

I found the burn in made a difference but the overall character showed from the beginning.  I don't recall: what did you select for your various caps (stock, Mundorf silver/oil, Auricaps, etc?????).  Did you post photos yet?  You know it didn't happen if there aren't photos....

John

John Kessel
Hawthorne Audio AMT K2 Reference Speakers
Paramount 300B w/MQ All Nickel Iron,  Mundorf S/G 5.5 uF,  and  Vcap Teflon .1 uF
Auralic Taurus Preamp/Auralic Vega DAC/Auralic Aries Streamer
and lots of room treatments!

Offline ebag4

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Reply #23 on: May 26, 2011, 02:32:20 AM
Quote from: InfernoSTi on May 25, 2011, 05:17:47 PM
Wonderful, Ed!  

I found the burn in made a difference but the overall character showed from the beginning.  I don't recall: what did you select for your various caps (stock, Mundorf silver/oil, Auricaps, etc?????).  Did you post photos yet?  You know it didn't happen if there aren't photos....

John

Thanks John.  Right now I have a pair of 2.2uF Obbligatos PIOs in the amp.  I also have a pair of large (think red bull can size) Ampohms that are currently residing in my modified T-amp that  I may switch out for the Obbligatos.  But I will probably listen to it this way for now.  

My unit is primarly stock except i am running it as a power amp and I used Azuma tube sockets.

I hope to get the base completed by this weekend.

BTW, I am pretty certain it happened, here you go!

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hawthorneaudio.com%2Fphotos%2Falbums%2Fuserpics%2F10060%2Fnormal_Circuit_Boards.JPG&hash=c60631830c5429fc8c5ba68f170c54de857a3d17)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hawthorneaudio.com%2Fphotos%2Falbums%2Fuserpics%2F10060%2Fnormal_front_parts_installed.JPG&hash=721364e4bc5299c7197669b283077ef277d5da6e)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hawthorneaudio.com%2Fphotos%2Falbums%2Fuserpics%2F10060%2Fnormal_wiring_complete.JPG&hash=9efc0ee9bde9e094bf4982b5688ab4a1de41352b)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hawthorneaudio.com%2Fphotos%2Falbums%2Fuserpics%2F10060%2Fnormal_base_front_unfinished.JPG&hash=973f449086c88b97275bea74318fca92c06af037)

Best,
Ed

GO CARDS!!!

Offline ebag4

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Reply #24 on: May 26, 2011, 01:38:53 PM
Someone on another forum recommended that I bolt the pillars on, I have always glued everything but in this case I thought bolting them on was a good idea so here you go!

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hawthorneaudio.com%2Fphotos%2Falbums%2Fuserpics%2F10060%2Fnormal_Legs_Bolted.JPG&hash=495823030f6cdec1a34945028f907f5ecff64134)

Yes, the rear right corner brace is smaller, there is less room here due to the IEC socket.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hawthorneaudio.com%2Fphotos%2Falbums%2Fuserpics%2F10060%2Fnormal_Legs_Bolted_all_frame.JPG&hash=97608c0b8a64b8f9abad2584fad47f9a89509361)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hawthorneaudio.com%2Fphotos%2Falbums%2Fuserpics%2F10060%2Fnormal_amp_and_base_unfinished.JPG&hash=a57e62c452d6ccbcc779baf508436e85ad833e52)

If the amp looks a little swayback that is because I haven't installed the braces for the chassis yet.

Best,
Ed

GO CARDS!!!

Offline InfernoSTi

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Reply #25 on: May 26, 2011, 05:08:34 PM
Very nice, Ed!  I guess it DID happen after all.  Those Obbli's should be a nice fit...I have been thinking about a nice set of Mundorf Silver in Oil 2.7uF caps instead of my Auricaps just to compare. 

I like the "legs" and I bet it sounds nice without the extra switches for the inputs and without the pot.  Congrats again!

John

John Kessel
Hawthorne Audio AMT K2 Reference Speakers
Paramount 300B w/MQ All Nickel Iron,  Mundorf S/G 5.5 uF,  and  Vcap Teflon .1 uF
Auralic Taurus Preamp/Auralic Vega DAC/Auralic Aries Streamer
and lots of room treatments!

Offline ebag4

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Reply #26 on: May 27, 2011, 03:15:46 AM
Quote from: InfernoSTi on May 26, 2011, 05:08:34 PM
Very nice, Ed!  I guess it DID happen after all.  Those Obbli's should be a nice fit...I have been thinking about a nice set of Mundorf Silver in Oil 2.7uF caps instead of my Auricaps just to compare. 

I like the "legs" and I bet it sounds nice without the extra switches for the inputs and without the pot.  Congrats again!

John
Thanks John.  I have a big pair of AmpOhms I am considering trying in this amp.  The highs are sounding a bit muted on some material to me, I am hoping that clears up with some burn in or perhaps I need to roll some tubes.  I am considering starting out with an in expensive tub like that JJ 12A7T you tried.  Any other recommendations are welcome.

Best,
Ed

GO CARDS!!!

Offline Grainger49

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Reply #27 on: May 27, 2011, 03:36:05 AM
Quote from: ebag4 on May 27, 2011, 03:15:46 AM
  .  .  .   I have a big pair of AmpOhms I am considering trying in this amp.  The highs are sounding a bit muted on some material to me, I am hoping that clears up with some burn in or perhaps I need to roll some tubes.  .  .  .  

No surprises here. I'm going to suggest adding a 0.1uF (or0.22uF) @600V KK Teflon in parallel with those AmpOhm caps.  But... always a but, you have to break them in first.  The relatively painless breakin instructions I have used for years are in this thread:

Relatively Painless Capacitor Break In Instructions

Teflon caps take a long time to break in, 300-400 hours.  But you get 89-90% of the way there in 100 hours, 4 days.
« Last Edit: May 27, 2011, 03:37:40 AM by Grainger49 »


Offline ebag4

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Reply #28 on: May 27, 2011, 04:03:09 AM
Grainger,
Thanks for verifying that what I am hearing is not unique and the tip on burn in.  I will try installing the ampohms which are already burnt in and if that doesn't bring up the highs by itself than I will try the bypass.  I have a unused solid state amp sitting here ready to burn in some caps for me!

Thanks again for the burn in procedure.

Best,
Ed
« Last Edit: May 27, 2011, 05:48:46 AM by ebag4 »

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Offline Grainger49

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Reply #29 on: May 27, 2011, 05:46:00 AM
Ed,

If the AmpOhms are burned in then you can clip them in with jumpers, you ought to have a dozen, just to check easily and quickly.


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