Elliott Sound Project 101 Rev C

[90scaraudio]

That Zobel does have a purpose...but if you are careful (accidentally running amp without load COULD be an issue), I guess its all good.

Paul, sorry to hear of your troubles. Check the resistor values. As far as the trimmer - if its a multiturn, you may have a while to go to get the bias to show up.

I built one over ten years ago with no problems (reluctantly sold to friend who loved it), and it started on first power up...BUT my second build a few years later, I could not get to work correctly....for years it sat in a drawer... The only difference on this build, from Rod's instructions, were I ran flying leads from board to the output transistors to better fit on a heat sink / case. The ESP forum had just changed web format and was zero help (it would not even let me register)...

I finally decided to put in another (bigger) case and solder the output transistors directly onto board, as designed, and it fired right up.

There is a mistake somewhere on the PCB. A magnifying glass looking at all the solder joints to eliminate solder bridges, component verification of value and orientation... you will find it.

Its a great amp circuit, and I would not give up on it...

Yes, reading the build guide, Elliott does say to use a 5uH to 10uH and a 2.2 to 10 ohm RL.
He wrote "The inductor can be quite small (around 5-10μH is about right), and must be shunted by a parallel resistance of between 2.2 and 10 ohms (10μH gives a -3dB frequency of 71kHz with an 8 ohm load)."

So I will install a 5uH/2.2ohm RL for this.

 

[wiseoldtech]

Depending on the design, ferrite beads on the output transistor leads can tame some issues.

 

[kffern]

My P101

This is my P101 build of a couple of years ago. No issues and emailing Rob directly is the best way. The website help is dominated by a some more keen on showing how smart they are.
My case should have been higher. I had to make a few mods.
Just listening to them on my just finished esl63s. They sound better than any of my other amps. (Holton 350w, rebuilt quad 405, Bryson 4bst). One day I will fit some better PS caps.
Hope you finish it.
Regards,
Kffern

 

[john65b]

Ha! That looks to be the exact case I was trying to use - the Cover and bottom support rails were to be cut to make fit (exactly like yours), but I was still worried that the Transistors would short to case, so I tried the flying leads - and had all sorts of issues...

How high did you bias?

 

[kffern]

I should add that they are dead silent. The 300va toroids are very old Aussie made, 40v, salvaged from a pair of PA amps. They hum slightly on startup but quieten down later.
Kffern

 

[john65b]

I used a cheap 500 watt 60vdc SMPS power supplies for both channels. Sounds great!

 

[kffern]

The amps I salvaged used a thin plastic sheet under the top cover. I think there is enough clearance but maybe I should do that here.
Kffern

 

[john65b]

I am using them on Quad ESL-988. Kinda deciding which amps sounds best - the Hypex NC400, the ESP P101 or an old Tripath TA0103A base amp I built...

I am not a big Tubeamp fan on these speakers - I think SS sounds better. The Quicksilver 8417 Clones sound good but not as good as the SS on the quads...

 

[paul stewart]

Not investing anymore time or money. One thing I have found out is do not invest in anything that is hard to find or stupid expensive. Going to sell my four boards and buy something State side with more stable power transistors, AND SUPPORT. Just getting one more amp UP and play my guitar.

Thanks for all the help.
AmpsLab.