DIY EAR 834p phono stage - a short evaluation/ test with those chinese PCBs

[nostromo]

As you have the valves mounted outside of the case, Did you have sufficient clearance for the resisters & small caps on top of the board & then  mount, All the bigger caps underneath the board?
  Nice Tidy build

yes... resistors and bypass capacitors on the "valves side"... capacitors and cables on the other side... turrets 10mm M3

I love watching the tubes light!!!

[Jay]

Looks damn fine to me 

Think my build is definitely going to have Valves & Trannys Outside the box 

[xdanx]

Look very good. Bravooo

[Jessica_K]

Anyone else have noticed this thread has finally beaten the mono Quads 41907 and counting

Robert

[analogadikt]

Just completed and working fine.

[spaceistheplace]

Anyone else have noticed this thread has finally beaten the mono Quads 41907 and counting

Robert

Haha!

I did not. A milestone and cause for celebration.

[spaceistheplace]

Just completed and working fine.

Nice layout and aesthetic!

How do you like it's sound?

[spaceistheplace]

Robert, in the original ground scheme you detailed with the douk PSU, how should one connect the case of a metal capacitor to ground?

Edit I read something that makes me think this isn't such a great idea:

-----

For anyone not already aware, a metal bodied oil cap shouldn't normally have its case grounded in a coupling position. A measurement this morning of the capacitance between either lead and the case of an ASC X386S 100uF came in at ~350 pf. The majority of tube circuits won't appreciate being shunted to ground with that much extra capacitance.

He then goes on to say:

[do not connect the outer metal foil to ground] in a coupling position. Do due diligence to ensure safety by wrapping the body with insulation and keeping it out of reach. Or use something else. The graph below demonstrates what happens [simulated] when a sample of the caps I measured have their cases grounded and are driven with an 12ax7a no-load.




----

With heavier caps I worry they will sag a bit and touch the pcb holes or perhaps react with the magnetic nature of the tubes.

But, for many years tube amps had these sorts of caps so I don't worry too much- but maybe some heat shrink around the entire casing?

I've placed some teflon tape underneath the caps to avoid contact with the pcb holes, but wondering if there's a better solution.

The .15uf cap between first and second stage seems to be of most importance, as it's close to V1 and is a bit cramped.

[spaceistheplace]

Also, I've been meaning to post this, as I have quite a few resistors at my disposal I figured why not compare them.

It seems to go against the belief that: Every resistor has a maximum power rating which is determined by its physical size as generally, the greater its surface area the more power it can dissipate safely into the ambient air or into a heatsink. I suppose this is also related to improvements in production of resistors, a given resistor winding geometry and technique, etc. but these aren't necessarily related in the photos.

But we must remember: it's not just about the size of the boat, but also the motion in the ocean!

Anyhow, take a peek. I will let you draw your own conclusions.



Another vantage point:




From left to right:

Dale CPF Metal Film 2W
Dale RN60 Metal Film Mil Derated .125W
Allen Bradley Carbon Composition .5W
KOA SPR Carbon Film 1W
Tepro RA Metal Film .5W
PRP Metal Film .5W
Dale RS-2B Wirewound 3W
Mills MRA5 Wirewound 5W
Dale RN65 Metal Film Mil  Derated .5W
Dale CPF Metal Film 3W
Shinkoh NOS Tantalum 1W
TKD CM2 Metal Film 2W (Seems like same body as audio note tantalum 2W)
Dale CW-5 Wirewound 6.5W
USSR Mil PTMN-1 Wirewound 1W
Kiwame Carbon Film 5W
USSR Mil C5-37 Wirewound 10W (an interesting dissection of a c5 resistor can be found here)

[Jessica_K]

There are two elements associated with the power a resistor will take. First the efficiency of the heat to reach the surface of the resistor (thermal resistance) and second the ease at which the heat that's on the surface is dissipated.

The former is dependant on the material covering the resistor and thickness of the resistive element. The second is mainlly the overall surface area, hence large wattage parts are metal cases and are expected to be bolted onto heatsinks

There is a further factor not related to the resistor itself and that is the manufacturers own rating, some are conservative and others are not. So a 1watt from one manufacturer may be cooler than 1watt from another

Robert

[GrooveGrinder]

power supply!!!

HYL FK!
That's the same case I got for mine!!!
I'll take a pic when I can....

Sorry I haven't been around.... been unable to get online for a bit due to tech crisis(s)...

FWIW:
A very EAR like knob..... for anyone who may want.... (and willing to spend..)

http://www.ebay.com/itm/322037445074?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

I might even consider splurging myself..... but the recess on that case is 39mm and the knob is 40....
Not enough shaft left on John's recommended rotary on/off switch....


Anyway, the details of that PSU will help me.... Layout is about what I have so far (just not drilled/screwed in yet)..
What is the black "can"? Aditional capacitance??
(sorry if that was already covered.... like I said... haven't been able to keep up lately)

[GrooveGrinder]

Anyone else have noticed this thread has finally beaten the mono Quads 41907 and counting
Robert

WOOHOO!!! Yay for us!!

[spaceistheplace]

Robert,

I have a hard time finding any fault with the Dale offerings (RN, CPF, PTF, NS etc.). But, curiosity always gets the best of me. The most striking difference in wattage vs size was the Mills MRA5 5W, which is what nudged me to put them all in a row.

If nothing else, it's neat to see them in a lineup.

As we're mostly way above required wattage across the board I suppose it more important to consider how the wattage, construction, etc. influences stability. The Dale/Vishays, Caddocks and so on have a lot more data in this regard than the more fancy audio types.

Speaking of which, I noticed these.. which may be an attractive solution for the RIAA resistor.. maybe it's splitting hairs though.

Michael Percy stocks a 787k (that's .4% tolerance of 790k?) Caddock resistor that will fit perfectly in the Xuling & Douk riaa resistor slot (.6" lead spacing)

Do you think this is "close enough" ?



CADDOCK TF020 Ultra-Precision Film Resistor - 787K ........ $9.25 USD each.
* Non-Inductive oxide design, 15ppm/°C TCR, 1% tolerance, .33 Watt to 70°Centigrade, 300V maximum operating voltage. * Constructed with Caddock Tetrinox film for long term stability of .01%/1000 hours, tinned copper round wire radial leads. * Excellent alternative to the more costly Vishay S102, and preferred over the S102 by some, particularly at higher Ω values where there is also a considerable cost savings. This is absolutely the most transparent resistor Caddock manufactures and ideal for ultra critical applications where the best possible sound is required. Values below 1.00K are identical USF340, but 0.1% & 5ppm Please take careful note of large physical size (.750" wide by .375" high).


However, using a RN55E, with following specs, I doubt the actual stability or ppm would be different, especially if derating further to maybe a 1/4W RN60E.


When a CMF55 (1/8th watt rated) part is run at 1/8 W in a 70 °C ambient environment, the resistor will generate enough heat that the surface temperature of the part will reach about 19 °C over the ambient temperature, and over the life of the part this could cause the resistance value to shift up to ± 0.15 %.
If the same resistor was instead run at 1/4 W in a 70 °C environment, the element will heat up to about 30 °C over ambient, and over the life of the part the resistance value could shift roughly ± 0.5 %.
And if the resistor was run at it maximum power rating of 1/2 W in a 70 °C environment, it will heat up to about 58 °C over ambient, and you could see the resistance value shift roughly ± 1 % over the life of the part.

Source: http://www.mouser.com/ds/2/427/cmfmil-223788.pdf & http://www.mouser.com/ProductDetail/Vishay-Dale/RN55E1002BRE6/

Funny how with better marketing / writers the Caddock sounds much more impressive.... but, 10-15k hours on the Caddock it approaches the same drift as the RN55E when run at rated power over it's lifetime. Who knows though?

I know Thorsten recommended using a 750k Caddock for his RIAA values in the original 834 mod thread.

We don't see many Caddocks here in the states.

[spaceistheplace]

Looks damn fine to me 

Think my build is definitely going to have Valves & Trannys Outside the box 

Perhaps you can do some measuring / take a few pics and maybe a few words on helpful construction tips- I can include it in the build guide.

I was even thinking of making a little printable template to show where to drill holes that one could tape to the chassis to get a nice uniform result....but I got sidetracked....

Also, I always wonder how others neatly tuck away all the transformer wires so they are invisible when they mount them up top.

[Chris65]

Anyone else have noticed this thread has finally beaten the mono Quads 41907 and counting.

That Quad thread views number is an aberration, not sure how that happened, but a thread with 3 posts is not going to be viewed that much.