Search found 693 matches
- 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, ...
- 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 ...
- 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.
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.
- 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...
- 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...
- 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...
- 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...
- 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?
While I was at it had taken a couple of pics of the SUTs. Does anyone recognise who they might be made by?
- Thu Sep 19, 2019 7:30 pm
- Forum: Assorted Stuff
- Topic: The Audio-Talk Cycling thread.
- Replies: 3776
- Views: 1178918
- 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:...
- 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.
Re: Phono Hum
How microphonic might the d3a be - it sounds like you think this may not have been necessary?
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?
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?
- 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 ...