Search found 693 matches

by little eddy
Thu Nov 07, 2019 6:46 pm
Forum: Everyones Projects
Topic: Snail Phono Pre
Replies: 234
Views: 115172

Re: Snail Phono Pre

By g2 on the el84 I assume you mean g1 on pin2? Yes your assumption is correct. The voltage on the lower triode anode is fixed by the upper cathode voltage which is set by the voltage on its grid. The upper triode grid voltage remains fixed at around 134V, as per the voltage divider on the output, ...
by little eddy
Thu Nov 07, 2019 1:40 pm
Forum: Everyones Projects
Topic: Snail Phono Pre
Replies: 234
Views: 115172

Re: Snail Phono Pre

So testing the cascode, as I increase the load current from 9 to 24mA, the only measurements that really alters is Vg2 of the EL84 and Va of the top 6N2P (tied together by the 1k5 grid stopper). They start at 187 and gradually fall to 170V. Vk of the 6N2P is steady at 137V up to then so all OK with ...
by little eddy
Thu Nov 07, 2019 12:52 pm
Forum: Everyones Projects
Topic: Snail Phono Pre
Replies: 234
Views: 115172

Re: Snail Phono Pre

Thanks Nick.

When I look at the MJ design, he has the EF86 g2 at 20V for Zener/Vk/Vg3 of 85V. Seems awfully low - is this correct? Assuming it is, I will target 26V, similarly 65V below the Zener voltage.

In terms of the EL84 g2, 220R/1W seems to be about the average?

Mike.
by little eddy
Thu Nov 07, 2019 10:12 am
Forum: Everyones Projects
Topic: Snail Phono Pre
Replies: 234
Views: 115172

Re: Snail Phono Pre

I was going to post last night but thought I'd investigate the current design further, even if it is just for me learning a bit more. Coincidentally I had been looking at an EF86 pentode regulator in MJ. I had drafted the attached, but inevitably have the following questions: Yes I can with a bit of...
by little eddy
Wed Nov 06, 2019 11:27 pm
Forum: Everyones Projects
Topic: Snail Phono Pre
Replies: 234
Views: 115172

Re: Snail Phono Pre

I'm going to make a series of measurements so I can better understand how the regulator valve conditions are affected as I increase the load current at 225V output. Is that the 'load' at 470k larger than would be expected and is this 'compressing' the voltage remaining for the two triodes. Update to...
by little eddy
Wed Nov 06, 2019 3:39 pm
Forum: Everyones Projects
Topic: Snail Phono Pre
Replies: 234
Views: 115172

Re: Snail Phono Pre

Nick. Did some testing with the full valve complement drawing around 30m, voltages as attached. Very strange the high voltage between the two 6N2P triodes. So as you suggested, tried on no-load (fine), and then gradually added valves. The regulator seemed to work fine @ 225V up to around 24mA, but t...
by little eddy
Tue Nov 05, 2019 3:58 pm
Forum: Everyones Projects
Topic: Snail Phono Pre
Replies: 234
Views: 115172

Re: Snail Phono Pre

Sorry but I need some help with the series regulator I inherited from the original builder as attached. To allow me to increase the valve operating points, I need to find an additional 15V. I had thought the output voltage was determined by the Zener, and 3 way voltage divider so Vout would be 91/11...
by little eddy
Fri Nov 01, 2019 5:06 pm
Forum: Everyones Projects
Topic: Snail Phono Pre
Replies: 234
Views: 115172

Re: Snail Phono Pre

So the enclosure bottom replaced with temporary sections to give access to the underside of the phono.

While I was at it had taken a couple of pics of the SUTs. Does anyone recognise who they might be made by?
by little eddy
Thu Sep 19, 2019 7:30 pm
Forum: Assorted Stuff
Topic: The Audio-Talk Cycling thread.
Replies: 3776
Views: 1178918

Re: The Audio-Talk Cycling thread.

Ray P wrote: Wed Sep 18, 2019 7:39 pmDistance: 22.7 mi Moving Time: 01:06:29
Pretty rapid
by little eddy
Sun Sep 15, 2019 2:50 pm
Forum: Assorted Stuff
Topic: The Audio-Talk Cycling thread.
Replies: 3776
Views: 1178918

Re: The Audio-Talk Cycling thread.

After a year out of the saddle, just had a very tough but rewarding 3 days in Yorkshire and Cumbria. Good quiet roads with remarkably few potholes. Plus some good food and beer in Ilkley and Dent with old college mates, shame about the Yorkshire drizzle all Monday. 160 miles and 12000ft over 3 days:...
by little eddy
Mon Jul 08, 2019 11:48 pm
Forum: Assorted Stuff
Topic: My Next Big Ride
Replies: 26
Views: 14806

Re: My Next Big Ride

Well done at nearly 9000 ft.
by little eddy
Mon Jul 08, 2019 9:02 pm
Forum: Beginners
Topic: Phono Hum
Replies: 20
Views: 13207

Re: Phono Hum

How microphonic might the d3a be - it sounds like you think this may not have been necessary?
by little eddy
Mon Jul 08, 2019 4:33 pm
Forum: Beginners
Topic: Phono Hum
Replies: 20
Views: 13207

Re: Phono Hum

I see the mechanical isolation, and remember MJ having some ideas in this. Wondering if the maglev units might be a novel option and not too expensive if can keep the weight down?
by little eddy
Mon Jul 08, 2019 4:16 pm
Forum: Beginners
Topic: Phono Hum
Replies: 20
Views: 13207

Re: Phono Hum

I see the mechanical isolation, and remember MJ having some ideas in this. Wondering if the maglev units might be a novel option and not too expensive if can keep the weight down?
by little eddy
Fri Jun 14, 2019 11:25 am
Forum: Everyones Projects
Topic: Snail Phono Pre
Replies: 234
Views: 115172

Re: Snail Phono Pre

Based on a few of Nick's posts, I have ordered one of these inverse RIAA cards: https://www.ebay.co.uk/itm/173886602640?ul_noapp=true I get how I can sweep through the frequency range using a sine wave input and measure the output of the phono to determine if I have a flat response. But I have also ...