Integrated Pre-amp with Line Driver + Phono + TVA's

[simon]

Something not like this...

[simon]

I'll send an updated parts list, schem and layout for your documentation package.

Andrew, Colin,

I'm getting an order together - is the revised parts list available by any chance? Particularly interested in which heatsinks are recommended. I'm quite happy with the way the skin on my hands is and I don't fancy the Dave The Bass school of speccing heatsinks by touch and degrees of skin removal .

[Andrew]

I hope to try some new ones out from Rapid, but I got home late tonight and so no time for experimentation, will tomorrow be OK?

cheers,

-- Andrew

[Andrew]

Hi Colin,

Do you want a circuit for the regulated heater supply? Or do you already have one?

cheers,

-- Andrew

[izzy wizzy]

If using the regulator, then try something like this.

cheers,

Stephen

[Andrew]

OK a quick look at heatsinks, I currently have 20deg/Watt on my test board an they seem OK, reasonably cool to the touch, however, I don't think these are man enough for the first MJE340 to sink full power, which is required if the unit is shorted to ground.

Rapid's 36-0150 are 17deg/watt and 36-0170 are 10.5deg/watt might be even better, but are a bit wider but may just fit on the layout I used.

Picture of the reg to follow.

cheers,

-- Andrew

[simon]

I hope to try some new ones out from Rapid, but I got home late tonight and so no time for experimentation, will tomorrow be OK?

cheers,

-- Andrew

No problem at all, I'm not in any rush. Happy to wait until you're happy .

I'd prefer to use Rapid (cos they're cheap ) but they don't seem to do the BZX84C15L zener. Are there any suitable alternatives that they stock?

[simon]

Thanks Stephen, that makes more sense. Am I not going to lose 80V doing this though?

[Andrew]

Apologies for the crap pic -but you get the idea....

[Andrew]

I hope to try some new ones out from Rapid, but I got home late tonight and so no time for experimentation, will tomorrow be OK?

cheers,

-- Andrew

No problem at all, I'm not in any rush. Happy to wait until you're happy .

I'd prefer to use Rapid (cos they're cheap ) but they don't seem to do the BZX84C15L zener. Are there any suitable alternatives that they stock?

I'm going to order form Farnell soon, I can add some if needs be, however, I suspect you won't find caps that have a suitable voltage rating at Rapid....do let me know if you do.

cheers,

-- Andrew

[simon]

That would be great Andrew, but when I checked Farnell they only had the US stock, and though they are only tuppence a go there's a £15.95 delivery charge. RS has them for 6p a pop.

[Nick]

but they don't seem to do the BZX84C15L zener. Are there any suitable alternatives that they stock?

BZX55C15 47-3036

Should be fine.

[simon]

Thanks Nick. Kits are just too easy .

[izzy wizzy]

I didn't really look too hard to see what current was being pulled by the stages. The idea is to isolate the stages from one another as there is substantial LF boost that causes motorboating at worst or a bloat in the lower frequencies if mild. Regulators control the tendency to LF drift by brute force. Valve regs aren't quite as brutal in this regard as their SS cousins. Passive solutions less so again. The idea is to isolate the 1st stage from the 2nd so they don't interfere with each other. Therefore it is a trade off as to how much volts you can spare to achieve this. Lower volt drop (smaller R) may mean a bit more capacitance. I tend to choose a C I have handy and increase the R until it sounds stable. Hope this helps with the ideas. Just fiddle about until it sounds right.

cheers,

Stephen

[Toppsy]

Andrew wrote:

Do you want a circuit for the regulated heater supply? Or do you already have one?

Andrew, the only schematic of the regulated power supply I have is the one you posted early on in page 2 in this thread. Is this still up to date or have you changed anything on this since?


Colin