Jay's EAR 834 Build now a Mk2 begins

[Jay]

She Lives & makes MUSIC 

[Jay]

Much has been done on the build since I last posted. The 834 really is making nice sounds
  More of everything, than with the Musical Fidelity Pre Amp
There was a problem with microphoney from as it turned out just one valve.
Also Hum but I'm getting rid of it bit by bit, with each steel addition to the chassis, though now it can only be heard if the cartridge is moved over to & above the PSU area approximately 4" away directly above the Tranny. Next ill make a top for the Can Ive put around the Tranny.
The Steel chassis has cost an impressive £20.00.
Now for some pics
Wiring diagram of the Star Earthing & commons only one channel shown




All switches are rotary from L to R    
On/Off   hole for LED,   Mute,   Vol  &  Input Selector.

Now It's time to wire up all the inputs + the SUT's, problem is it'll mean turning it off to do it  
Then the outer garments to make

[timelog]

Good work, but have you checked that powerunit and tube area get cooling air enough when in picture box seems to be quite closed.
Single components can run quite hot in closed box and shorten other componets lifetime. Using resonance damping material covering
part of box walls is good idea, but it also can be block part of cooling of electronics if there is no effective airflow.

[Jay]

Have been monitoring that very thing. I checked the Valve temps & they run at about 37 deg C each.
With the cover on & after about 5 albums the steel top is just warm to the touch in the area of the valves,  away from them the top plate is still cool.

There are vent holes underneath. & I will be cutting holes about 20mm in dia above each valve, as the tips of the valves are only a couple of mm below the top plate.

[Jay]

Spent All yesterday & a couple of hrs this morning wiring the, Input sockets / Output Sockets, Volume,  Mute switch & the Selector switch.
 Still have the SUT's to wire. All is good so far
This is All Silver screened wire Thats not very flexible

[ZZMoko]

Looks great..very neat where did you buy the wire from?

[Jay]

Would you believe at an Auto Jumble  so no provenance but the spool it came off did appear genuine.

Now have SUT hum issues 

 

[Jay]

Their have been issues with hum since connecting the SUT's for the MC stage, & as the wiring is rather cramped, I figured that it would be easyer to RIP IT OUT & START AGAIN GURRRRRRRR.
This Silver twin core Screened cable is very stiff especially when its in short lengths

[ZZMoko]

And did Edwyn Collins provide any inspiration....is it now silent as there later career 

[Jay]

    Most of the stiff silver wire is soldered back on & I gave it a blast with the Hair Dryer to soften the wires into shape. Even so two wires did brake off & had to be re soldered  

I shall also run a small half moon file round the chassis holes just to be on the safe side, before putting it back together properly.

[Jay]

After ripping it all out & starting again, All is well no nasties except for a bit of hum, still seems to be mains hum
I have some copper sticky back foil & Aluminium sticky back foil would any of this help?
On the MC side there is a bit of hum when the arm is touched but not on MM

The selector switch, the block underneath is for the individual commons the two bits of copper wire were cut off, it seemed an effective way to bring them all to the same place before going to the board.

The RCA socket holes have been enlarged just a bit to make sure theres no shorting, with the Star point connections removed there is now no continuity between the commons & any part of the chassis.


Sounding very nice though

[needlekiller]

nice build! but why not put the input-switch direct on an shielded pcb? my guess is, keep it short and simple! no additional wires wtich could pikup hmm only on thought

[ZZMoko]

All looking very neat...I'm glad it's turned out so well for you.

My Hammond Case has turned up so I hopefully when I can get a spare day I'm going to have to start my revision of my original build...this time I'm going to go with a separate PSU and see if that gets rid of the tiny amount of hum my current build still suffers from.

[Jay]

I had thought of that ish but I don't have or Know of a shielded switch pcb ?

hope you get some time to start building again

[Jessica_K]

Is there hum only from the SUT. I removed the last very small amount of hum from my SUT
I have no hum from the Phono amp just a small amount of noise at silly volume with no input that I put down to just component noise prob from the cheap valves I'm using

The issue was my own fault I had introduced a ground loop between an earth post I fitted to the metal case (I built the SUTs myself using LL9226's and my own PCB) that was also connected to all internal grounds. I had connected the post to star point WRONG that shorted the nice signal input earth flow directly to the star point causing a loop Rookie mistake from an 40 year pro lol

Just check that.

Oh and here is a strange one I have never been able to work out I have never been able to connect the TT gnd to amp ground without introducing hum. It's always been quiet as a mouse with it disconnected regardless of the amp used

Jessica