DIY EAR 834P TRLH Phono Stage - Build Guide / Parts List

[Jay]

Hi smoorenc,
We use our real names just to be nice n friendly, looks like you getting off to a good start.

Id like to point out that, This thread is for the TRLH BUILD GUIDE. As the guide needs to be kept as short as we can keep it. This will help others to build the 834 & without it getting lost in 80 odd pages.

 Can you move your build to the other thread that we use for general building of the 834 

Hear http://www.lencoheaven.net/forum/index.php?topic=20984.0

Thanks James

[Scott Moore]

Sure Thing

Scott

[spaceistheplace]

Updated with new base tube selections, as well as the "tube rolling" section in the "appendix" based upon my personal findings which you can read in it's entirety here. (Too long to repost)

Added info on Robert's PSU and added a recommendation for the purchase of a blank Xuling board paired with Roberts PSU. Once I get my hands on one I will add it to the build guide with photos, etc. In the interim, I'll leave the Douk PSU assembly info in the guide.

[spaceistheplace]

For European builders I've added the direct source for the Pessante 3U recommended chassis, which is made by HiFi2000 in Italy. Purchase Link

[spaceistheplace]

Fixed:

A few missing/incorrect part #'s and incorrect links.

Added:

Added an option for a nice 1 resistor RIAA solution instead of two in series to reach ~790k Link Here

Swapped:

1. Kiwame for Ohmite Little Devil Carbon Comps to help tame oscillations Link Here

2. Amphenol Mil Connectors ($70 for a set) for much lesser priced and equally effective option:

Was able to evaluate some umbilical connectors which would be an excellent replacement (for much $$$ savings over the mil amphenols).. wanted to use them myself first to verify their quality/safety. They are available in M+F Pairs for $9 USD with free shipping from china. A great bargain. Link Here

Here is a better image of these connectors being used with another DIY Phono Stage ( Vacuum Tube Audio PH16 )

[spaceistheplace]

Updated important oversight / error on the grounding diagram Section 4.4. I circled the wrong PCB Holes to specify the B+ wiring and have revised it.

So you can see what has changed I've placed a big WRONG DONT USE on the erroneous one.

(Click for full resolution)

Correct:



Incorrect:

[spaceistheplace]

Decreased the size of the thread photos to make everything easier to browse through.

Made sure all photos linked to full size photos when you click on them.

[spaceistheplace]

Added grounding procedure for those using capacitors with metal bodies:

For those using capacitors with metal bodies, use an exacto knife or file to scrape a small area exposing bare copper, from which to run a small wire to ground the casing. Also, use some heat shrink around the cap after soldering the wire, or some teflon or electrical tape underneath to prevent the capacitor housing from making contact with the PCB Holes. Do the same with some heat shrink to keep the leads from making contact. Here's an example of how it might look at the 0.15uf location (notice, they are grounded to the spare negative pcb hole in the 33/47uf electrolytic location).

[Scott Moore]

Added grounding procedure for those using capacitors with metal bodies:

For those using capacitors with metal bodies, use an exacto knife or file to scrape a small area exposing bare copper, from which to run a small wire to ground the casing. Also, use some heat shrink around the cap after soldering the wire, or some teflon or electrical tape underneath to prevent the capacitor housing from making contact with the PCB Holes. Do the same with some heat shrink to keep the leads from making contact. Here's an example of how it might look at the 0.15uf location (notice, they are grounded to the spare negative pcb hole in the 33/47uf electrolytic location).

hi John,

Should I do this to the metal long caps running down the outer sides?



Scott

[spaceistheplace]

hi John,

Should I do this to the metal long caps running down the dies?

Scott

No scott that's unnecessary from my experience. Mostly it's if the V1 caps are metal. Plus the 1uf caps you have aren't the heavier metal ones that can be problematic.

Can you please start a new thread so we can better track your progress and help out?

Keeping track of everyone's builds is getting confusing.

The idea is to keep this thread as spare as possible so it can be the most easily browsed reference point for builders and to track changes to the guide.

[spaceistheplace]

1. Made some semantic alterations based upon Chris' suggestions.

2. Added an example wiring diagram for the Antek AS-05T280 that was recommended in the build guide. Most transformers will have similarities.

The full 4A is not required for 6.3V (total current is 0.9 x 1.6 = 1.4A so 2A is plenty) but the extra buffer can not hurt and makes for a cleaner wiring.

260V is used instead of 280V as extra would just be wasted heat, and is sufficient to give us the 285 we are shooting for at output. 250V secondary could also be used.

Datasheet here:http://www.antekinc.com/content/AS-05T280.pdf

This is assuming a single fuse and a filtered socket (like this ) so I will no address X or Y caps or multi-fuse arrangements.

For USA Voltage:



For UK Voltage:

[Pillo69]

This thread is interesting.
I'm looking at the diagram and I see some variations that are discussed. The R6 resistance of the Cathode follower is indicated in some places should be 120k in use with 12AX7, 68k is suitable for ECC81 and ECC82.
Can someone clarify that point ?.

Another question, this is the final assembly scheme?

[spaceistheplace]

Hi Jose,

No the schematic is "as received" before modification.

It was part of Roberts explanation of the original circuit, to illuminate what the changes are meant to achieve, why, etc.

Yes you are correct on the cathode follower however it's been suggested post-Thorsten Mods 22k might be a more appropriate value for a 12AU7 in V3. 68k will also be ok.

I'm happy with a 12ax7 and 120k.

The guide walks you through those changes. It is a walk though directed towards those unfamiliar with tube circuits.

Those changes, roughly:

Removal of R7, R14, C4 rumble filter.

Bridging C4 with 100R to tame any possible oscillations.

More precise RIAA values

Various bypassing

Parts selection for long term stability

And so on.


(PS I've used in the past a modified PAS3's Phono (rebuilt) and my thought would be that you might very much like this)

[Jay]

Pictures & diagrams make it so much easier to understand 

[Pillo69]

Thanks for your attention.
As a phono preamplifier I am using a PH6 in the PASS, but I want to test the EAR.
For me it is easier to make a PCB (PASS dimensions), using an external regulated and stabilized power supply, which manufactures for the preamplifier, also feed the filaments per channel.
So it is easier for me to understand with a circuit diagram. The reference numbers mentioned in the thread can not be distinguished by not having the EAR PCB.
I would like you to review the following scheme in case I have made any errors, or I have omitted any component.