audio-talk

Hi Simon,

I've yet to crack solid state regulated HT, but I do have the DC heaters for the 6 valves working fine, including the ~2.4 Amp supply for the Aikido. So, we should also be able to 'clip lead' in the LCR's regulated heater supply so you can hear it with DC heaters.

cheers,

-- Andrew

It's that difference that has led to me building these amps to find out for meself. It's the best way. But before that I've got the L99/plinth and poss a hadcock or other u/p to do plus a replacement Phono pre as my Lite Audio mush-monster is letting the side down with out Philips Denon Step-up's. ...

Right I think I found the problem, the Aikido section of the PSU draws nearly 70mA when you include the current for the op amp buffers and the current shunted by the reg etc. The wattage limit for the 1/4 watt current limiting 47R resistor into the reg is, guess what, ~70mA. The result, was that whe...

Will, that second drawing, I've seen that done before with low Z RIAA (i.e. an LCR). Its very interesting, if you work the maths, it turns out, approximately as real world to theory ever does, that the tx, which looks like a step down, and is really, also allows an increase in gain roughly equivalen...

Yes, absolutely, I realized that just after posting, but an input TX might be a good way of doing that. So, having noted the downside of the idea, I'd be back to suggesting a decent valve suited to cathode follower operation and loaded with a constant current sink, might be more elegant. Unless you ...

Nick wrote:Ain't nobody here but us chickens.

Cluck, ckuck, cluck, cluck, cluck........squark....cluck...peck.peck....cluck

Hi Colin, 6m lines. I would knock yourself up an Aikido pre, or use a low Rp valve 5687, 12BZ4 (can't recall the number exactly, its the one Steve likes in pre's). But I really think an Aikido would be the way forward, 6N6P on output valve duty. Hmmm....Do you need gain? I'm wondering if Aikido woul...

Yes, its going to have a DC component and an AC component but the AC will be at 100Hz-ish now and won't be anywhere near a sine wave, which means, depending upon your meter and how sophisticated it is, TRUE RMS etc, you'll not be reading what's really there.

cheers,

-- Andrew

Toppsy wrote:
Thinking about it for wood one would probabley require CNC routing rather than lazer cut. I wonder who Peter C uses for his CNC cut speaker cabinets?

Colin

Ask Clive, I think he had someone do his speakers on a CNC.

cheers,

-- Andrew

Here's the link.

http://www.izzy-wizzy.com/audio/preampnew.html

OK checking thngs with a fresh head its not quite as bad -36db, so we need to find 36db in the next stage. A triode connected D3A would manage that. However, I'd be interested on what the panel think of the 5842 or the trioded D3a as the input valve in this config? One reason I started with a pentod...

I did some sums with a 5842 into a 3.14:1 tx (10:1 in squared terms) suitable for 15k:1k5 and driving the 1k5 RIAA. The output is down at -40db so if I got it right we'd need to get gain 100 in the following stages, this rules out an Aikido and most other valves I know would need the second step up,...

I would personally connect 2, 7 and 5 together and thence to the 68R which goes to ground. I certainly used both cathode pins 2 & 7 on the C3g I use as a driver in the tx-coupled Aikido.

cheers,

-- Andrew

Hi Dave,

On the C3g, connect

2 & 7 to the cathode above the 68R
3 is the anode
6 input grid
4 to the voltage ref tube
1 & 8 heaters

cheers,

-- Andrew

Back to regs, here's the data sheet that started it all off for solid state HT regs from Nat Semi by M Maida. http://www.national.com/ms/LB/LB-47.pdf They look quite attractive, low voltage drop, wide range of operation, no need for seperate heaters etc, low component count and offer the potential f...