Jay's EAR 834 Build now a Mk2 begins

[Jay]

 :grin:Have shamelessly robed from other builds, If you recognise some of your work  

OK Have bitten the bullet & ordered a full 834 kit with valves from Germany.
  Order canceled Full kit didn’t arrive.  Stocks seem to be running out.
Another kit minus valves has been ordered, this time from China judging by the delivery time.  poor communication skills at DOUK, Now have a tracking number that seems not to work !


Golden Dragon valves have been ordered.
 These they tell are All matched

http://www.ebay.co.uk/itm/162198451785?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Toroidal Transformer



http://www.ebay.co.uk/ulk/itm/301308565631 this one from Germany In stock

   Hammond 154E choke 20H 20 mA  
From Bluebell in scotland



2,  Good quality volume pot or stepped attenuator.
  

http://www.ebay.co.uk/itm/Valab-23-Step-Ladder-Type-Attenuator-Potentiometer-50K-Log-Stereo-/222310382880?hash=item33c2bb3d20:g:dNQAAOSw~uhUqwpt
 Ordered.
3, where in the circuit should it go.
   Hear


4, Would also like to be able to switch between input sockets.
http://www.hificollective.co.uk/switches/alps-2-pole-6-way-selector-switch.html
 This switch will allow up-to 6 separate inputs Great for all those TT's


  


 http://www.hificollective.co.uk/switches/extension-kit.html
Bracket & extension bar  Out of stock so couplers Ordered  I can make shaft & bracket.

Lorlin Also from HiFi Collective these switches 4A DPST Rotary Mains Switch


I'd like to have an LED to show, Power On, any suggestions for a simple solution ?


5, SUTs decent cost effective ones.
    MCs I have, are AT OC109   & Dennon 103r.
PAIR OF PARTRIDGE 6:1 COPPER MOVING COIL STEP UP TRANSFORMERS

This is how to wire these suts

These were british manufactured during the 1960s by Partridge to a very high standard they use mu metal cores and come in a shielded metal can
 specs as follows
DCR ( dc resistance) 20 ohms
Impedance  30 ohms
Output impedance is 10K ohm
 with DCR of 250 Ohms

Actual findings  for each SUT would these be classed as a good match.

 Input  21.1 Output 247.5

 Input 20.7 Output 237.6

 does this equate to  a ratio of  11.7 & 11.47 ?

6, Also where in the circuit would they go.
 From the MC RCA input to the input of the MC selector switch  ??


7,  If 2 box set up is used these plugs/sockets for the link between boxes. 400v rating
   5 possibley 7 core cable needed for 2 box system that can cope with HT voltage.
Have 5 core cable.
   Plugs & sockets will need to be like this

http://www.ebay.co.uk/itm/262401194416?var=561197899203
  Ordered. 2 off  These same plugs / sockets are also available at Maplins

8, For the Internal signal wire I will be using silver plated copper screened cable.
 Wasn’t expecting it to arrive like this in its own presentation box….hope they don’t see this build as I’m going to chop off those very nice plugs..


Best case I’ve found so far £87.00 with P&P !

http://www.ebay.co.uk/itm/272177414847?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

General Info


 

David's build
http://www.lencoheaven.net/forum/index.php?topic=22195.0


Here is a link to the mods for the 834
http://www.goodsoundclub.com/GetPost.aspx?PostID=2052

Various posts that may have some bearing on the build


Quote from: needlekiller on January 18, 2016, 03:12:32 PM
1. the 6,3 volt dc can checked on the heater dc output terminals.
2. the correct value can only checked with the valves!
3. there are 2 resistores on the board, in post 51 the res have 0,22 ohm
4. so if the heater-voltage with tubes on board is highre then 6,3v dc, change the 2 res to 0,33 or 0,47 ohm
cheers puli

Quote from: Lawrence
one thing i would do after its been up and runing is double or quad wire for the powersupply feed...I will almost bet that your preceived dynamics and dynamic range will be better  
Hum can be a tricky thing to track down. The heater wiring is well known for producing hum (hence the reason to twist the wires).
A simple thing you can do is move your output signal wiring to the other side of the PCB, away from the heater wiring, see if that helps.

Regarding hum: You need to have a binding post for the tonearm ground wire.  The binding post should be electrically connected to the chassis.  Also, the ground from the circuit board should be connected to the same point.

 A 2 Amp fuse has too high current rating.   transformer has around 60W power.  With a mains voltage of 230 V the current is 60 / 230 = 0.26 A.  I think that a 500 mA slow blow fuse would be better.  It has more chance to save your amplifier from burning up, if something fails.

Quote from David
my plan was to use these Kiwame resistors as they are very closely matched and sound nice in the Pre amp that I built http://www.hificollective.co.uk/components/kiwame.html and they are not too expensive.
 As to capacitors I was thinking of these as they offer 1% matched pairs by request http://suppression-devices.com/ansar/ppa-audio-capacitors.html
 For the power section I read these Panasonic caps are supposed to be good http://www.ebay.co.uk/itm/111020269027?_trksid=p2055119.m1438.l2649&var=410226786835&ssPageName=STRK%3AMEBIDX%3AIT
 I hope that helps and good luck with build.
 For the version shown it's 285 x 130mm total. 85 x 130mm for the PSU board, 200 x 130mm for the circuit PCB.
You'd need 80-85mm internal height for a case if the valves are inside.

Waiting now for a few more parts that should arrive by X Mass.
& still need to sort a box

Any help with the questions Iv'e raised would be most welcome
If you see any errors please do point them out.
Am going to build it mostly stock for now with the above parts & supplied components.

[itskeith]

Bloomin great James and thanks for posting. May well be following you down this DIY route at some stage. Having this will make it a lot easier to get started.
 

Post edit:
A summary of the build cost would also be very helpful (please) 

[Jay]

Valves, Attenuator & Sockets all came today Ive put in an Oder for a few more sockets as they are very good for the price.

Keith,
As to cost, the Board with Kit of Resistors & Caps have been included, but thats all I'm waiting for & the 2 box connector plugs which I may not use.

  Total so far, is £321.00 including P&P where necessary.

 This dose not include a Case & sundry bits n bobs like mains plugs & sockets, fuse, wire etc stuff that most of us have   down the shed  

When I get the Case sorted ( from whats on offer & the cost I most likely will try & make something myself )  that will dictate the kind of knobs I use so add another £20 or so. Ill try to do the case for less than say £ 50.00, that will keep the whole thing to under £400.00.
 Is that a good deal for a DIY 834P ?
 
 Have no idea what an upgraded version ( better Caps & resistors etc ) would cost as no one has put an overall figure on them  

Be good if someone who has done a resistor & cap upgrade would put full details on this thread

[willbewill]

Nice resource Jay

Here are some ways of implementing an LED - working on AC input power

http://www.seekic.com/circuit_diagram/LED_and_Light_Circuit/AC_Line_Powered_LED_Pilot_Light.html

http://www.eleccircuit.com/mains-voltage-indicator-with-a-led/

https://www.eeweb.com/blog/extreme_circuits/mains-operated-led-circuit-schematic

[Chris65]

I'll try & cover some your points Jay...

3, where in the circuit should it go.

Volume control - there is provision on the board for the volume control connections.

I'd like to have an LED to show, Power On, any suggestions for a simple solution?

Again, there is provision on the PSU board for an LED to be connected.

7,  If 2 box set up is used these plugs/sockets for the link between boxes. 400v rating
 Plugs & sockets will need to be like this
http://www.ebay.co.uk/itm/262401194416?var=561197899203
 

Personally, I'd be a little dubious about using those for high voltage, up to you of course. The 5pin & up connectors are rated for 250V.
There are better connectors around, but you'll pay more of course. e.g http://uk.rs-online.com/web/p/mil-spec-circular-connectors/0475836/
See Jaco's build: http://www.lencoheaven.net/forum/index.php?topic=20984.45

Have no idea what an upgraded version ( better Caps & resistors etc ) would cost as no one has put an overall figure on them 

Well, the very first post of the main EAR834p thread said: "Building that kit should be possible to finish for less than € 400; with using higher quality parts and matching parts as I did it should be finished for less than € 550."

Be good if someone who has done a resistor & cap upgrade would put full details on this thread

Not sure what the details could be? 'Upgraded' components would simply replace the supplied ones....
The supplied resistors (unless they've changed) are actually very good.
And unless someone has built with the supplied components & then upgraded, it is not really possible to compare the changes.

[Jay]

Thanks Chris,

Yes I do see where the volume goes now.
Didn't realise that there was provision for an LED. At least that saves having to work out ware it would go & making up a little circuit for it.
Looks like Im building a one box set up anyway.

It would of been good to have had a Proper wiring diagram as it would make things Nice & Clear as to where things connect to on the board.
 The best Ive managed to find was the block diagram just below the circuit diagram.
 
Will,
   I know my first post on this build was very long but it does make it fairly clear whats involved in sourcing parts for Kits etc, at least for a fairly standard 834p. Hope it can be of use to others. & thanks for the LED links I'm sure Ill need them Later

[Jay]

The board has now left Hong Kong  

Have been doing some drawings for the case, As I'm going to Make it myself & It's going to be  Heavy

[Jay]

 Hear is a drawing of the 'seen' part of the case

 It will be made from This

  Haven't decided wether to keep the SUT's outside in shiny cans or inside yet

[ZZMoko]

Sorry it took a while to answer your minimum height question....

I reckon 70mm is about as low as you can go....my stage had to go in a very narrow shelf so I cut down the PCB stand offs to about the shortest but still safe level I could go to and with the valves in place they just about make it.

To be on the safe side if I would aim for 80-90mm when you are designing your case.

[Jay]

Thanks David for those heights.

Like your build the valves will be exposed, But mine will have to be on stilts
 Ive found the Missing ECC 83 so now have a full set of 'Made in England' Mullards, + (New Golden Dragons) & Gold plated ceramic valve bases.

 Iv'e allowed 75mm without having to rebate or cut anything so looks like it will work.
 Though the overall height still partially depends on the piece of Olive wood yet to be received that will be used for the sides.

One more thing I can't tell precisely till I get the board is the distance from the end of the signal board to the centre of the valves,

Ie from the earth point end of the board I think that they are 25, 75, 120 Is that close

[ZZMoko]

When I've got time I'll take mine apart and measure for you.

[Jay]

Above & beyond 

[Chris65]

One more thing I can't tell precisely till I get the board is the distance from the end of the signal board to the centre of the valves,
Ie from the earth point end of the board I think that they are 25, 75, 120 Is that close

Pretty close . I measure 30-75-120mm.

[Jay]

The board as shown in the first pic arrived today  so will set it out in the newly built metal part of the case tomorrow, pics tomorrow.
 

[Jay]

The board & metal chassis & most of the general components

I Split the boards by scoring with a sharp knife along the dotted lines on either side of the board & it snapped in two quite easily
Since there is no parts list etc for this Pre
 I thought I'd include a component count


These are All the components in the Kit except the screws & pillars.

 
Most of the Resistors are pre-fitted to the boards but not soldered

On signal board 
 34 Resistors
 14 Caps   
 3   Valve bases
     
On PS board.
 9 Caps 
 8 Diods 
 8 Resistors,  7 if you'er going to use a Choke.
 2 Transistors
 1 LED  (there was an extra one included in my kit )

 16 screws & 8 pillars