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

[Gone & forgotten]

Post deleted on request of a banned member.
It was about Chinese PCB's for the EAR 834p phono stage.

[ZZMoko]

Looks great do you have a link for the kit?

[niclaspa]

Interesting build!  I look forward to your listening impressions!

[ecosprog]

I just couldn´t resist having a go at this. I´m a big fan of the EAR 834 and have a point-to-point clone I built a couple of years ago. Unfortunately, this version has a small amount of hum that, despite all my efforts, remains.

So, about a week ago the PCB arrived.



I managed to find most of the missing caps in my spare parts box, as well as, an unused transformer that I bought for another project that never materialised. I only need to order the larger power supply capacitors to complete the board.

A hours work with the soldering iron and I was ready for the case work.



As the casework for this project involved simply drilling holes of various sizes (excluding the IEC socket) it was completed fairly quickly. Another hour in the workshop and I was ready to mount the components.







This was certainly one of the easiest build I have ever done. So, how does it sound? Well, really nice. Lots of gain and almost silent. At full volume the hum is only detectable with my ear right next to the speaker, and certainly not detectable in the normal listening position.

It has now taken pride of place in my setup on top of my new DIY passive preamp with matching enclosure.



This build was made with stock parts which included no boutique components. I think I will order some better capacitors to replace the Vishay´s currently in there, but I need to look around and find something that doesn´t involve silly money.

Based on the build cost for this clone, it is a hard phono amp to better. I am finding myself listening to this more than my Bottlehead Reduction. If this continues I think the Reduction will have to go.

A big thank you Rolf for bringing this DIY project to my attention.

[rfgumby]

Can you put in a steel shield between the power section and the audio section?  That might help.  I think your coupling caps were a good choice too, those really help "voice" that preamp, and being a phono preamp it seems they need a little longer break in than one might expect.  Or maybe it's just a lot of record sides which seem like they should be an hour, but aren't!   

Does the Reduction have the C4S (constant current source)?  The design might include it these days, I'm not up on BH for a few years.

I like the 834, I did professional mods on them on many occasions, maybe 8 of them total.  Caps and high speed rectifier diodes seemed to offer the best improvement from a mod perspective.  The chassis were always a nightmare to work on or mod, so I'd say your design there is a nice improvement over the original layout.  Maybe not for hum, but for everything else!  The originals had to be carefully laid out like open heart surgery, yet trying to disconnect the wires keeping the bundle together were tricky to disassemble and reassemble perfectly.  It seemed there was always just enough time between mods for me to forget the best way to work on them, but I would remember quickly.

Ooh, and quality signal path resistors yielded improvements too.  I personally prefer Caddocks in that application.

Great build, good luck!

[Chris65]

Super nice work again Reese.
Didn't you have the cheap EAR-clone from Ebay, prior to rebuilding of it? And this beats both?
I've used some Obbligato Gold caps recently & are decently priced depending on size. (from Parts Connexion in your homeland)

Does the Reduction have the C4S (constant current source)?  The design might include it these days, I'm not up on BH for a few years.

It's an option/upgrade kit. All of us here have fitted it

[paul300b]

I bought one also. The projects keep piling up.

[ecosprog]

Can you put in a steel shield between the power section and the audio section? 

Interesting you should ask this as I have a piece of 1.5mm steel plate cut and ready to fit in the case. the reason it is not there is that I need to paint it and didn´t have any primer and black paint sitting around the workshop. I hope to get it painted, and fitted, over the next couple of days.

As for the Bottlehead Reduction, yes it does have the C4S kit fitted.

Super nice work again Reese.
Didn't you have the cheap EAR-clone from Ebay, prior to rebuilding of it? And this beats both?
I've used some Obbligato Gold caps recently & are decently priced depending on size. (from Parts Connexion in your homeland)

I did buy the cheap clone from eBay a few years back and was really impressed with it. I borrowed the transformer, and power supply board from it, to build the point-to-point version. It sounded slightly better, but had a bit too much hum.

I have been looking at some better capacitors, I can get the Obbligato´s from Hificollective in the UK, and they aren´t too expensive. For now I am just going to listen to it as much as possible and let things settle a bit. At the moment I am really enjoying it. It is hard to pick between the Reduction and this EAR clone on sound, but the EAR is ahead on gain which is a big benefit for me as I am using a passive preamp.  Baring and major changes I think the Reduction may be going up for sale along with a couple of other phono stages.

[mred]

Looks to be a good kit and a fine build Reese.

I like your equipment rack too .

[ecosprog]

Thanks Ed. This must rank as the easiest of my DIY builds so far.

I love my equipment rack, until I have move it. The shelves are 30mm thick slate which is hard on the back.

Over a week in the system now and still loving this amp. It works really well with my new Grado Platinum Reference, a cartridge I was sure I wouldn't like and would have problems with. No dancing, or humming.

[paul300b]

Can I use this transformer that they sell along with the kit? 
http://www.ebay.com/itm/40W-power-transformer-for-tube-amplifier-output-0-6-3V-8V-2-5A-220v-input-/271832368201?
It is rated for 220v, but New Zealand voltage is 230v?
BTW, I received the board and am impressed with the quality. Nice.

[Chris65]

That would be fine Paul. You may notice Rolf is using that very one.

[ecosprog]

Can you put in a steel shield between the power section and the audio section?  That might help. 

In an effort to keep Scott happy I finally got some paint and finished the steel partition for the phono stage.





I´m glad I added this partition because the noise floor has dropped to a point where I can say it is pretty much silent.

Now I just need to settle on some tubes and we´re all done. At the moment I am running with a NOS Philips Jan 12AX7WA followed by some well used long plate 12AX7 RCA´s. Problem is, I have a large selection of 12AX7 tubes to play with, so there are quite a few combinations. However, for now I think I´ll stick with this setup.

[paul300b]

Cool, two inputs for 2 turntables I see?
I think it would be cool to have a 47k and a 100k input.

[paul300b]

That would be fine Paul. You may notice Rolf is using that very one.

Cheers Chris, ordered!