I agree.... the real issue might not be the uTeslas generated by the DVM but the current passing in the coils.
Several years ago I managed to burn the coils of a cheap MC while trying to determine the correct polarity using a voltmeter working with one 1,5v bat.
Several years ago I managed to burn the coils of a cheap MC while trying to determine the correct polarity using a voltmeter working with one 1,5v bat.
After a few days listening to the RIAA, I can say that I am really happy with the final result. A big improvment from my previous non cascoded build. More dynamic, more resolution, more 3D sound, more of everything. Also it is very balanced. It' s like having another stereo! It was well worth the effort put in building it.
Also FYI, I changed to battery bias bias and put an 470nF FT-3 output cap (I liked this very much! I would like to have a similar value of Mundorf silver gold oil to compare. It is going to be difficult to better it.) on my #26 pre and things improved even more.
Everybody serious about records should give this a try. It' s one of the best sounds I ever heard.
Also FYI, I changed to battery bias bias and put an 470nF FT-3 output cap (I liked this very much! I would like to have a similar value of Mundorf silver gold oil to compare. It is going to be difficult to better it.) on my #26 pre and things improved even more.
Everybody serious about records should give this a try. It' s one of the best sounds I ever heard.
Attachments
Nice one VG, enjoy. What is that blue wire in the phono? Some grounding to chassis? Also what type is the output twisted pair? That No26 DHT line pre is a big machine now I see it with its separate supply box, by the way. Should have taken quite a construction effort.
the blue wires were temporary are they are removed now, as I run a seperate ground wire from the PS box. The picture is from yesterday.
As I have two big 10H chokes, heater pregulation with 2x15000uF per channel, 3 transformers, 2 anode chokes and 2 SSHV, I do not think I can do one box!
This was morphed from my previous 12b4 pre, so there are a few extra holes!
As I have two big 10H chokes, heater pregulation with 2x15000uF per channel, 3 transformers, 2 anode chokes and 2 SSHV, I do not think I can do one box!
This was morphed from my previous 12b4 pre, so there are a few extra holes!
To aid ventilation, you planned it all along.🙂 What kind is that cotton jacket(?) twisted pair wire you use for linking the phono output to the boards?
Tryed with 220R Caddock MK132, 1st impressions is that the sound has more punch or dynamics so more mids & lows also more noise than the Vishay Tx2575 but can't come back to 150R, when I have the money I will order 220R Vishay Tx2575 to Michael Percy. Thank you for great input Nick, now is time to tweak the Riaa HF cap so I will change 15nF76 SM to 15nF teflon film & foil, I will tell you what happens....
Salas, this is silver wire gold plated with cotton insulation.
I have some VDH wire also that I was planing to use but couldn' t find it when I was bulding it! Found it later of course! Think I should change?
I have some VDH wire also that I was planing to use but couldn' t find it when I was bulding it! Found it later of course! Think I should change?
OK. Keep 150pF extra caps to make tuning steps. VG's 15mA Vjfet custom simplistic lends it self for 15n straight Teflon by its intrinsic alignment I used, yours may need a bit more than 15n or not. You will see.
Input wire must be shielded, but output it depends, I think. Also my interconects are not shielded right now.
No if you don't get any buzz noise. You get any? You got no Tx in that box at least.
With my DCB1 I have no noise, even on the horns.
With the tubes more of a little bit hiss. I do not think this is a problem of the phono. I always try to route my cables away from the transformers, power lines etc.
With the tubes more of a little bit hiss. I do not think this is a problem of the phono. I always try to route my cables away from the transformers, power lines etc.
If there is no buzz (zzzz 100Hz to 1kHz harmonic noise) from the source, just different hiss from the line preamplifiers does not have to do with the twisted pair, and you may keep it since your system tonality is great as it is now you say, not to disturb it.
I don't have shielded output wire either. iMHO it is better to avoid it if you can to minimize capacitance. I usually don't run shielded interconnect either. only when I have to.
I have a couple of shielded interconnects which seems to me less dynamic than the ones, pure silver, that I am using now. With the tubes, there is slight buzz only listening right at the speaker. I am certain with different tubes and a little work on layout can make things better. Tape noise from analogue recordings is a lot louder.
For the moment I am listening one of the best sounds ever listened.
For the moment I am listening one of the best sounds ever listened.
vgeorge,
Nice build by the way. thevery slight buzz could be a bunch of things.
If you look here: http://www.diyaudio.com/forums/tubes-valves/178027-gyrator-frequency-response-6.html#post2384228 some of your perception may be found. Sheilding adds alot of capacitance, and resistance plays a role as well. In this post I was playing with attenuation and cable length.
Nice build by the way. thevery slight buzz could be a bunch of things.
If you look here: http://www.diyaudio.com/forums/tubes-valves/178027-gyrator-frequency-response-6.html#post2384228 some of your perception may be found. Sheilding adds alot of capacitance, and resistance plays a role as well. In this post I was playing with attenuation and cable length.
Thanks for the link, but keep in mind the very sensitive speakers. Probably in normal 90dB speakers you won' t listen anything. Also I' m not done with the pre.
If you use twisted pair you are adding capacitance also....if you use parallel wires it's capacitance symbol so exist also capacitance, less what still have...so doesn't exist a couple or more wires without capacitance, you can minimisize the effect if you use a Litz geometry or separate with the maximum lenght possible the wires (this last one difficult to do for chassis wire)
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