Chinese PCB's for a DIY EAR 834p phono stage

[Jessica_K]

I can only give a guess here

Black and white to 115V input
Blue or green pairs output 250V
Black and orange 6.3V
Yellow green earth

 

The toroidal is a lot easier to understand
Join red to red and black to black to 115v input
Grey and yellow 260V output
Join blue to blue and green to green 6.3V output
Purple earth

Robert

[Hubertrs]

Hello to all
inspired by your work, I decided to build my own EAR834p ,It took me a week but I'm more than happy.

[spaceistheplace]

I can only give a guess here

Black and white to 115V input
Blue or green pairs output 250V
Black and orange 6.3V
Yellow green earth

 

The toroidal is a lot easier to understand
Join red to red and black to black to 115v input
Grey and yellow 260V output
Join blue to blue and green to green 6.3V output
Purple earth

Robert

Wow if you are confused, then I'm afraid!

Very strange that input and output leads are coming out of the same side of the transformer.

So, that means on the douk I can discard entirely the red 230 (unless installing a 230 voltage switch), one pair of 250V (either blue or green pair) and the brown 8v and blue 5v wires?

Do both purples have to be merged for a ground or there are each separate grounds?

Can I open up the transformer and unsolder the leads somehow? What is the protocol for dealing with the unused outputs?

I'd like to try to use the douk as I have no idea what I'd use it for if not this. I will also test with the toroidal and compare differences if any.

Thanks again, as always.


John - USA

[spaceistheplace]

Wow if you are confused, then I'm afraid!

Very strange that input and output leads are coming out of the same side of the transformer.

So, that means on the douk I can discard entirely the red 230 (unless installing a 230 voltage switch), one pair of 250V (either blue or green pair) and the brown 8v and blue 5v wires?

Do both purples have to be merged for a ground or there are each separate grounds?

I can't wrap my head around why some are single lead, others are double and the 6.3v on the antek requires two pairs?

Do all 4 blue blue and blue green go to the input on the 834 in the case of the antek?

Can I open up the transformer and unsolder the leads somehow? What is the protocol for dealing with the unused outputs?

I'd like to try to use the douk as I have no idea what I'd use it for if not this. I will also test with the toroidal and compare differences if any.

Thanks again, as always. Sorry for so many questions.. I'm trying to slowly grasp the theory behind this.... being taught to fish, so to speak.


John - USA

John - USA

[spaceistheplace]

I think I am understanding... so with the antek example, joining black to red and black to red is for 230, red to red and black to black for 115?


John - USA

[Jessica_K]

I think I am understanding... so with the antek example, joining black to red and black to red is for 230, red to red and black to black for 115?

That is correct. Coils in parallel for 115V, coils in series for 230V

So, that means on the douk I can discard entirely the red 230 (unless installing a 230 voltage switch), one pair of 250V (either blue or green pair) and the brown 8v and blue 5v wires?

Do both purples have to be merged for a ground or there are each separate grounds?

Can I open up the transformer and unsolder the leads somehow? What is the protocol for dealing with the unused output

It is my take that the single colour wires blue and green is because the output is AC so there is no volts and 0V and you can use either way round (you can ignore phase)

So you need only blue or green. ( it is possible to join the two in parallel but you would need to find the phase so they are in phase and you don't need the hassle or the power)
5V, 8V and 12.6V wires are not needed so do not use either of the purple wires nor the blue or the brown

I would not open the transformer but instead cut the wires leaving enough to wrap insulation tape for safety. No need to do anything else with them

Robert

[Jessica_K]

I can't wrap my head around why some are single lead, others are double and the 6.3v on the antek requires two pairs?

Do all 4 blue blue and blue green go to the input on the 834 in the case of the antek?

The reason that some transformers have 2x6.3 volt coils (like the antek) is that they are usually rated to provide say 2A each, so when joined in series they can provide 2A @12.6V for users that wish to wire their valves using 12.6V or as in our case 4A @ 6.3V when joined in parallel to power the heaters in the 6.3V arrangement.

The Douk transformer is strange as it does not appear to offer this dual arrangement, so you still have the 6.3V and 12.6V but as separate windings

How to wire the Antek


How I think the Douk should be wired !!


Robert

[spaceistheplace]

Getting closer! Slowly making my way through some transformer basics.... a lot harder to follow instructions and then also learn actually what is happening electrically.. phew.

How does this look? Leads obviously not soldered, just for illustrative purposes.

Also, to throw a wrench in it the antek also had different colors than the spec sheet! However it was minor instead of a second blue green pair it was an orange brown pair. I believe this is correct?

Wanted to see everyones thoughts before I wired her up.







I should be going from iec ground to power pcb ground and then route to ground on the main board I believe... but didn't reflect that in the photo.. ran out of purple wire!

Also assuming that the 250 is what splits into two leads for each channel, while the 6.3 is one? How do I know which is the positive 6.3v wire on each pcb?


John - USA

[Jessica_K]

I am unable to view the images good enough until I get home however I can answer that the IEC ground goes to the star point and you are correct about the 250V DC is the one thats split and the 6.3V is single. You do not need to worry which way the 6.3V is wired as it only feeds the heaters that are isolated from everything else

Robert

[Jessica_K]

That wiring looks good to me, I would use a more beefy wire for the 6.3V dc to the amp board.
I have just reminded myself of the spec of the valves and each tube takes 0.3A of heater current so requirement is around an amp from the supply.
on that transformer the spec is 2A per winding so you have enough current with only 1 winding and not need to join them together.

When you do power up for the first time check the 6.3V DC as it could be high and a series resistor may be needed to reduce the voltage, I would not run them higher than 6.8V personally and better to be less that 6.6V

Robert

[predator67]

Just curious, how much would a DIY build for this cost?

[Jessica_K]

Depends a lot on the quality of components used.
The initial kit can be bought for about £90. Then add a box say £100 then the tubes can cost as low as £21 for 3. Then transformer £30. Finally RCA's on/off switch and wire say £20
So this adds to £260 for a nice sounding phono amp

Improving caps could add about £30 or a lot more, adding better tubes could add £30-£200+
Better transformer, add an inductor, silver wire.....

Once started improvements can be made anytime

Robert

[predator67]

Sound wise would it be better than say a Lehmann black cube se ok used at £300? Is it comparable to the factory Ear834?

[Jessica_K]

Hi Lawrence

I will have to let others comment on that as I have not heard either
The kit design is basically the same as the original EAR so I would expect a family resemblance

The EAR has always suffered with the "accountants touch" in that the quality of parts have been to max profit and or minimise sale price. A DIY version should improve on those sound qualities that are inherent in the design.

As for a Lehmann it's a solid state design and comparing it to a tube depends a lot on personal preferences. I would always take tubes over transistors

Robert

[spaceistheplace]

Sound wise would it be better than say a Lehmann black cube se ok used at £300? Is it comparable to the factory Ear834?

I don't think it's wise to compare these clones to factory as i think most of the builds you see here have better stuffings than any 834p from TdP.

I believe the black cube se is just the black cube with a separate toroidal power supply.

If one assumes a 4x-5x markup to parts the black cube costs ~200-250 USD in parts total. I imagine it costs less, but let's use that for sake of discussion.

My guess would be that that sum along with some elbow grease put into an 834 clone would be money much better spent.

Obviously parts do not tell the whole story, and more expensive parts in a poor circuit won't do you much good- but it illustrates the point and it's well established that the 834 is an exceptional design to start with.

If you want solid state there are also other high quality DIY phono stages that you can peruse builds of here. There's an excellent thread on modifying a Chinese VSPS knockoff by RCAGuy which apparently gives excellent performance and is versatile for a variety of different cartridges. You might also want to look into the Salas Folded Simplistic as well (higher performance, higher cost, more learning curve).

It's documented in a variety of forums that some who have no acquisition restrictions whatsoever prefer a (heavily modified) 834 to all other phono stages regardless of price.

A lot is based on personal taste, but my hunch is that for the price of a black cube se on the used market one could build something that wipes the floor with it if you have the patience and fortitude.

Again, all usual caveats apply.


John - USA