Built-in D'lator: To shield or not to shield

[lbradshaw]

I just installed an built-in D'lator in my 2x6L6 test build. The layout file 97_ODS_HRM_loop.jpg was helpful. I think that might have been Normster's layout. I ended up just using one Resistor and Cap to make an extra node for the d'lator power. I know there are some that say you need as much as 4 extra filter caps. But, I got the voltage where I needed it, and everything seems to work fine. YMMV. Anyhow, I also read some about shielding the built-in D'lator. I am trying to minimize the amount of shielded wire I use. So, I am wondering, of those who have made amps with build-in D'lator did you use shield in that section? If so where, etc...

[greiswig]

Some seem to think that part of the mojo is the capacitance of the shielded wire rolling off a bit of high end. Some of the stage photos I've seen show guitar cords (not patch cables, 15'-20' of guitar cord) connecting the amp to the D'lator. You'd be hard pressed to put that much cable into your amp.

Arguably, you could simulate this with some capacitors strategically placed...and you could even put them on a switch so you'd know which you prefer.

[heisthl]

I've done quite a few of them now and my experience is they are very susceptable to being noisy when built in, I would shield any run longer than 2", even then it will be noisier than an external unit. At a minimum use a 40uf filter at the dropping resistor fed from B+2. Here's how I do it if I can only use a single node for power (voltages in Red):

[lbradshaw]

Some seem to think that part of the mojo is the capacitance of the shielded wire rolling off a bit of high end. Some of the stage photos I've seen show guitar cords (not patch cables, 15'-20' of guitar cord) connecting the amp to the D'lator. You'd be hard pressed to put that much cable into your amp.

Arguably, you could simulate this with some capacitors strategically placed...and you could even put them on a switch so you'd know which you prefer.

Yeah, hear the capacitance adds "Mojo". As it is, without long cables, the D'lator seesm to round off the highs a bit. I don't know that I would want it even duller by adding something 180pf to ground. But, it is a test build thus far, so It is always worth a try.

I've done quite a few of them now and my experience is they are very susceptable to being noisy when built in, I would shield any run longer than 2", even then it will be noisier than an external unit. At a minimum use a 40uf filter at the dropping resistor fed from B+2. Here's how I do it if I can only use a single node for power (voltages in Red):

Thanks for the info and schematic. I see that stand alone D'lators are shielded to and from the board to the input/output jacks. 4 total I think. So, currently I have shielding from the input/output jacks(2) to the d'lator circuit built into the amp. I just wanted more input as to if anyone thought I needed more then that.

Why do you think the D'lator power node needs at least 40uf. My PI/OD/CL tubes all are feed by 22uf caps. So, I figure that would be good for the d'lator tube as well. If there is a good reason to up the value, I will have no problem doing so.

Thanks again.

[heisthl]

Why do you think the D'lator power node needs at least 40uf. My PI/OD/CL tubes all are feed by 22uf caps. So, I figure that would be good for the d'lator tube as well. If there is a good reason to up the value, I will have no problem doing so.

Thanks again.

The PI rejects hum, your OD is geting 44uf and your CL is getting 66uf, are the lights turning on yet?

[lbradshaw]

The PI rejects hum, your OD is geting 44uf and your CL is getting 66uf, are the lights turning on yet?

Ah... Lights are on low, but they are working now... I was not thinking about it that way.

Thanks..