audio-talk

Hi
I checked the battery bias and the grid definitely measures about -1.3V.

I faffed about and moved G3 to the cathode and still get 60V on the anode and a current of 19mA. I think I will stop tonight and try more tomorrow if I have time.

Cheers
Ian

Hi Mark,
On stage 2 I have both G2 and G3 connected to the anode via 100R grid stoppers. Is that the problem should I move G3 to the cathode? I must admit I did that part on auto-pilot!

Hi Nick, the problem is in stage 2 not stage . I agree that the IDSS guides the current of stage 1

Cheers
Ian

Hi, Latest update. I am now running D3A in every valve position and this brings the gain up to being pretty much fine (certainly much better then with the E180F/6J9P). Bass also seems improved. I am running the two valves on the output with battery bias as per Mark's schematic. The main issue now is...

Hi Mark I will try the D3A in the second position and report back. The PSU is a CCS with two voltage stabiliser tubes (I have a 56nf cap across the stabiliser tubes to keep the noise down). You were right about the current limiting and voltage drop as the phono stage drew more current. It did drop o...

Hi, The valves above the jFETs is a D3A with 103V on the anode and drawing 14.8mA (the jFET source resistor dropped to 4.7R to achieve the current draw). The second stage valves are 6J9P with 62V on the anode with a 12K anode resistor. I was wondering about putting D3A in the output position as well...

Hi, I finally got round to building the jFET phono as shown in Mark's schematic and am having a few issues I hope someone might be able to help. Initially I built exactly as the schematic showedand the sound was really detailed but thin, like it was missing an octave or more of bass. Also the gain w...

Hi Mark, Yes, I will build it, it would be useful to know which way to think regarding the matching though. Hopefully Nick might enlighten me at some point. I had a quick Google to try and find articles on the importance of matching, and whilst there is loads on how to do it, there seems little (eas...

Hi I thought I would resurrect this thread as I am interested in trying a phono without the need for an SUT. I have managed to source some 2SK369's and have been measuring their IDSS in order to match them. The process of measuring the IDSS is straightforward but as I thought about it I became confu...

6mA per jFET was what I found in the thread. I couldn't find any info on the GR BL issue. The BL version that I could find was nearly twice the price of the GR and given I need to buy at least 10 to match it would be far more economical if the GR's were ok. Though of course if they are inferior then...

Hi Mark, I was looking at your schematic for the J-FET/triode phono-stage as I am interested in hearing a phono-stage without the use of SUT's. I was wondering with the 2SK369's did you use the GR or BL versions? The BL takes more IDSS (8.0-16.0mA). I found some BL versions at sensible prices, but w...

To avoid digging around for the schematic of Andrew's original C3G phono stage. This is the one I modified as detailed above.

Hi, I have been using a phonostage designed by Andrew that uses a C3G and ECC88 for the last couple of years and it is excellent. Recently I rebuilt it with the following changes: 1. Changing the ECC88 for a triode strapped E180F. 2. Split the HT with separate salas SSHV2 shunt regulators for the C3...

I have recently gone back to using vinyl as my primary listening source. The reason being a total rebuild of my phono-stage, which is based on Andrew's C3G design (I will write up with my findings about the phono when I can find the time). Anyway, back to the topic. I have just bought a copy of Sufj...

I have a habit of building my PSU's in separate cases to their associated pre-amp, digital streamer etc. It makes me wonder if I should add ferrite clamps to all the HT cables. Even if the RF doesn't cause highly apparent instability I imagine that it is better to keep it out. Given how cheap the cl...

Hi, I bought a ferrite clamp and a large a ferrite bead. I threaded the bead over the HT and umbilical and also put the clamp round the umbilical (belt and braces). The ferrites were placed round the cable immediately before the plug into the phonostage. When I switched on I was met with absolute si...