Search found 567 matches

by RhythMick
Wed Sep 18, 2019 11:55 pm
Forum: Everyones Projects
Topic: Valve DAC
Replies: 28
Views: 2303

Re: Valve DAC

If I can ask an honest and perhaps devils advocate question, what's the reason for using valves in the DAC cores? Curiosity? Or is there a genuine expectation that valves will bring something special to this? I've been waiting for someone to ask and the answer is very simple - because I can - so I ...
by RhythMick
Wed Sep 18, 2019 7:34 pm
Forum: Everyones Projects
Topic: Valve DAC
Replies: 28
Views: 2303

Re: Valve DAC

I for one would love to hear this.

If I can ask an honest and perhaps devils advocate question, what's the reason for using valves in the DAC cores? Curiosity? Or is there a genuine expectation that valves will bring something special to this?
by RhythMick
Sun Sep 15, 2019 4:47 pm
Forum: Everyones Projects
Topic: We are delighted to announce ...
Replies: 21
Views: 1954

Re: We are delighted to announce ...

45 driving 300B sounds interesting
by RhythMick
Sun Sep 15, 2019 2:21 pm
Forum: Everyones Projects
Topic: We are delighted to announce ...
Replies: 21
Views: 1954

Re: We are delighted to announce ...

Thanks both. Definitely for me. It started out as something to play while I make the improvements to my PP amp. I had the good quality components left over from early SE builds so while the build is rough the components and layout were as good as I could make them. Compared to my PP amp as it stands...
by RhythMick
Sun Sep 15, 2019 10:35 am
Forum: Everyones Projects
Topic: We are delighted to announce ...
Replies: 21
Views: 1954

We are delighted to announce ...

... the arrival of a new build in the early hours of Saturday morning. Weighing in at some arm stretching weight, this is essentially a SE version of my all-DHT, interstage coupled PP amp with the exception that it's 26-71A-300B instead of 26-71A-45. It's a rough build for now, the PSU especially. T...
by RhythMick
Tue Aug 27, 2019 7:15 pm
Forum: Everyones Projects
Topic: Question re grounding
Replies: 4
Views: 708

Question re grounding

Hi all My amp is 3 stage, each is valve rectifier into LCLC. Transformer coupling between stages. Each stage uses entirely separate mains transformer secondaries, and each stage is grounded to star earth exactly once, at the bottom of the cathode resistor. Each circuit is arranged with chokes in bot...
by RhythMick
Mon Aug 26, 2019 10:37 pm
Forum: Everyones Projects
Topic: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
Replies: 1102
Views: 131107

Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Thanks. Work has dragged me away from hifi I'm afraid. I'll check later this week.
by RhythMick
Sun Aug 25, 2019 3:21 pm
Forum: Everyones Projects
Topic: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
Replies: 1102
Views: 131107

Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

izzy wizzy wrote:
Sat Aug 24, 2019 5:15 pm
Check the value of the 47k resistor feeding the 100u capacitor. If it was low or has been shorted via a solder blob, the cap will charge up stright away rather than following slowly.
Ok thanks will do
by RhythMick
Sat Aug 24, 2019 4:07 pm
Forum: Everyones Projects
Topic: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
Replies: 1102
Views: 131107

Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

I just finished 6 of the boards. All test well except 1, which produces the right voltages but behaves differently. By which I mean it goes directly to the set voltage without the slow start, and adjusting the trimmer pot gives an immediate reaction where the others move more slowly. I can check sol...
by RhythMick
Tue Aug 20, 2019 3:11 pm
Forum: Valves
Topic: Recommendations needed for high quality valve bases
Replies: 3
Views: 1065

Recommendations needed for high quality valve bases

The last valve bases I used looked great (black bakelite) but have screw in pins. I thought that was a benefit until I overtightened a couple after they kept coming loose.

So I'm after recommendations. Ideally copper or gold plated copper contacts, ceramic for low capacitance. What do you all use?
by RhythMick
Tue Aug 20, 2019 3:08 pm
Forum: Beginners
Topic: Help interpreting 2nd/3rd Harmonic values on WE datasheet
Replies: 11
Views: 1410

Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet

Many many thanks. I use a calculator called HandyCalc on Android and it allows me to create functions which are really quick and easy. I'll create one for this.
by RhythMick
Tue Aug 20, 2019 9:14 am
Forum: Beginners
Topic: Help interpreting 2nd/3rd Harmonic values on WE datasheet
Replies: 11
Views: 1410

Re: Help interpreting 2nd/3rd Harmonic values on WE datasheet

Nick wrote:
Mon Aug 19, 2019 9:53 pm
Yes, so for example 40dB is 1%, 20dB is 10%
Ok thanks Nick. How do you convert dB to %
by RhythMick
Mon Aug 19, 2019 9:44 pm
Forum: Beginners
Topic: Help interpreting 2nd/3rd Harmonic values on WE datasheet
Replies: 11
Views: 1410

Help interpreting 2nd/3rd Harmonic values on WE datasheet

I stumbled across a WE datasheet for the 300B which included a table of operating points showing 2nd and 3rd harmonics, expressed in dB. Screenshot attached. Now I'm reasonably competent with maths, but will readily accept to dB being a weakness of mine. As a measurement it's a ratio, right ? So in ...
by RhythMick
Mon Aug 12, 2019 8:36 am
Forum: Everyones Projects
Topic: GM70 PP
Replies: 151
Views: 11589

Re: GM70 PP

Ok I overstated. Fair cop. I'm well chastised. "Everything should be made as simple as possible, but not simpler" isn't right either - it references what's possible but not what is optimal. And of course everyone will have their own view of what is optimal. I was simply trying to say that if it work...
by RhythMick
Sat Aug 10, 2019 2:18 pm
Forum: Everyones Projects
Topic: GM70 PP
Replies: 151
Views: 11589

Re: GM70 PP

Simplicity rules