I can change between transformer coupling and capacitor coupling by just connecting the rca leads to different sockets. Yes I'm still using the UX210's in the pre and basically my system has been in fully transformer coupled state except when I was burning in the coupling caps for a short term. I don't see the point, for my own taste, to use cap coupling unless the gain is too small. Right now I have full DHT signal path and the gain is still enough with full transformer coupling. Even more so if I use 6SN7 or similar higher µ tube in dac/pre/driver stage. I know, my system is slightly difficult to grasp even though it is very simple, at least for me 
. But one cap coupling option is still good to have for the very low level recording, when played with DHT's, for example 101D --> 101D --> 101D --> 300B. If I change one tube to 6SN7 or similar; 101D --> 6SN7 --> 101D --> 300B then the gain is enough for everything.
. But one cap coupling option is still good to have for the very low level recording, when played with DHT's, for example 101D --> 101D --> 101D --> 300B. If I change one tube to 6SN7 or similar; 101D --> 6SN7 --> 101D --> 300B then the gain is enough for everything.
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Your system is definitely working in harmony. Does that mean that you are you are using the same output transformer as the 101d for the UX201a? That would be very exciting if it were possible.
I am now considering upgrading the interstage and output transformers in the line magnetic 503pa to Noguchi finemet........ your fault
I am now considering upgrading the interstage and output transformers in the line magnetic 503pa to Noguchi finemet........ your fault
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Your system is definitely working in harmony. Does that mean that you are you are using the same output transformer as the 101d for the UX201a? That would be very exciting if it were possible.
I am now considering upgrading the interstage and output transformers in the line magnetic 503pa to Noguchi finemet........ your fault
Yes same transformers. UX201A has quite high Rp but it is still manageable with these transformers imo.
Bandwidth of the pre gets better as the Rp of the tube get's lower.
"Muuntaja" means transformer in Finnish, they got left behind.
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Thanks LasseYes same transformers. UX201A has quite high Rp but it is still manageable with these transformers imo.
Bandwidth of the pre gets better as the Rp of the tube get's lower.
"Muuntaja" means transformer in Finnish, they got left behind.
Hi Legis,
Out of interest, have you tried a series stacked cree diode cathode bias? There is some interesting findings out there.....
I would be interested to see what are you biasing your 101d's at? I have to place a parts connexion order and was thinking of trying some diodes.
Just a thought....
Out of interest, have you tried a series stacked cree diode cathode bias? There is some interesting findings out there.....
I would be interested to see what are you biasing your 101d's at? I have to place a parts connexion order and was thinking of trying some diodes.
Just a thought....
Hi Legis,
Out of interest, have you tried a series stacked cree diode cathode bias? There is some interesting findings out there.....
I would be interested to see what are you biasing your 101d's at? I have to place a parts connexion order and was thinking of trying some diodes.
Just a thought....
No I haven't tried diode biasing. Try it and tell what you think? Got me interested, what finding are you talking about? More clearer and cleaner sound, that I have heard regarding diode bias, but as does everything in audio, it divides opinions which one is better. Can one leave the cathode bypass caps out when using diodes, also with line level DHTs (does not add hum) ?
IIRC the cathode voltage is 8-9V with my lowish anode voltage and 1k cathode res.
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Tried LED bias yesterday quickly. I quess the resistance over three red LED's were/is too big as the channel started to hum slightly and also played somewhat quieter than the other channel, which tells that "cathode degeneration"/local feedback was happening. Also sound was grayer and rolled off, which tells the exact same thing in a transformer coupled stage (unbypassed cathode res rises output impedance Re times tube's "u" or sth. IIRC).
I'm wondering what diodes have the smallest resistance when operated at 4-10mA...
I also realized that diode bias might not be optimal in a system where one strives to be able to roll different types of tubes since the cathode voltage will always be the same with diodes. With resistor bias the tube will always bias correctly when the cathode res is at the correct range. Also resistor bias can counteract or "tune into" an aging tube's changing parametres which the diode bias cannot do if I understand correctly.
The most optimal system for (unbypassed) LED/diode bias might be system with IdH tubes, resistor loaded anode and capacitor coupling?
I'm wondering what diodes have the smallest resistance when operated at 4-10mA...
I also realized that diode bias might not be optimal in a system where one strives to be able to roll different types of tubes since the cathode voltage will always be the same with diodes. With resistor bias the tube will always bias correctly when the cathode res is at the correct range. Also resistor bias can counteract or "tune into" an aging tube's changing parametres which the diode bias cannot do if I understand correctly.
The most optimal system for (unbypassed) LED/diode bias might be system with IdH tubes, resistor loaded anode and capacitor coupling?
Ordered some 2W non-mag Audio Note tants for my Allnic H-3000 RIAA also. I had already changed 1W tants (with AN Kaisei bypass) for it's cathodes but what the heck, 2w is better. (why did I even buy the 1w in the first place about a year ago?) Also the transformers' secondary loading resistors will be 2W AN tant. They cannot be removed (tried it also), the freq response is wider when the secondaries are loaded.
I will also change the noval tube sockets to Audio Notes.
If looking for a fully transformer coupled RIAA, then Allnic might make/be some of the best ones out there. RLC-equalization and simple layout is a plus. Fully transformer coupling is uncommon breed among commercial audio because it's the most cost intensive way to do properly. I don't know if there even is another manufacturer to offer fully transformer coupled RLC RIAA.
I will also change the noval tube sockets to Audio Notes.
If looking for a fully transformer coupled RIAA, then Allnic might make/be some of the best ones out there. RLC-equalization and simple layout is a plus. Fully transformer coupling is uncommon breed among commercial audio because it's the most cost intensive way to do properly. I don't know if there even is another manufacturer to offer fully transformer coupled RLC RIAA.
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An externally hosted image should be here but it was not working when we last tested it.
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Wow Legit, you have been busy. For some reason the images don't work.
My output and chokes arrived today from Japan
As a quick question... how are you wiring them up on the input as there is 2x 2.5k brown/ red - orange/Yellow? I am so excited to install them and the output centre tap?
For se out are you using the grey/black or grey/white (centre tap)?
On a side note, I am building a SE type 50 amplifier which should be some fun.
My output and chokes arrived today from Japan
As a quick question... how are you wiring them up on the input as there is 2x 2.5k brown/ red - orange/Yellow? I am so excited to install them and the output centre tap?
For se out are you using the grey/black or grey/white (centre tap)?
On a side note, I am building a SE type 50 amplifier which should be some fun.
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Wow Legit, you have been busy. For some reason the images don't work.
My output and chokes arrived today from Japan
As a quick question... how are you wiring them up on the input as there is 2x 2.5k brown/ red - orange/Yellow? I am so excited to install them and the output centre tap?
For se out are you using the grey/black or grey/white (centre tap)?
On a side note, I am building a SE type 50 amplifier which should be some fun.
I used google translate to identify the wires on the trafo like written on the spec pdf: http://www.noguchi-trans.co.jp/digitalcatalog/main/fm10k600ct.pdf
Red and orange together for 10k pri SE. There was some confusion when I was deciding the polarity of the pri. I cannot remember if I connected the "black dot" side to anode or to power supply to get absolute phase correct.
Good, you are getting there. J&K TVC's sounded overly smooth and somewhat "confused" at the beginning. All trafos take time to settle. I'm interested what you you like of them compared to your current volume - do you still have Intact Audio AVC's wired?
Hi Legis,
I found the same with the polarity and have the primary's in series. Just so much better than stock. I have wired in the Slagle tvc's and they were a really big improvement. I will be soldering in the chokes today for a quick listen and then figure out the potting process for all the transformers. Did you prefer them after potting? I did think of potting them in roofing bitumen......
I found the same with the polarity and have the primary's in series. Just so much better than stock. I have wired in the Slagle tvc's and they were a really big improvement. I will be soldering in the chokes today for a quick listen and then figure out the potting process for all the transformers. Did you prefer them after potting? I did think of potting them in roofing bitumen......
I did not listen them unpotted. I have potted some other transformers before after having used them unpotted some months. Potted was better in that case, I remember the improvement was quite big, but it also depends on the transformer (how loose it's windings are prior potting). Noguchis are good anyway.
Bitumen has bad dielectric constant performance, does it really sound good? I believe it will rise the parasitic capacitance more than normal potting agents. Why not epoxy or some other plastic resins? Based on the smell I think Noguchi pot's their own transformers with some kind of polyesther that has some filler, could be sand. It could also contain some small steel/amorphous/whatever flakes, or then they are just dark sand grains.
Make sure and measure with a multimeter that all transformer covers get grounded via the attaching screws. Also check the output voltage with the new chokes, their DCR is around 500ohm and stock chokes have around 1kohm IIRC. I suggest to get rid of the regulator and the other silicon the coincident has in the anode supply, and just make it as a regular CLCLCLC-supply. The ripple of this supply with three 30H Noguchi chokes is so small (couple uV or even pV class) that any active regulator itself makes more noise than the ripple is (I presume).
Bitumen has bad dielectric constant performance, does it really sound good? I believe it will rise the parasitic capacitance more than normal potting agents. Why not epoxy or some other plastic resins? Based on the smell I think Noguchi pot's their own transformers with some kind of polyesther that has some filler, could be sand. It could also contain some small steel/amorphous/whatever flakes, or then they are just dark sand grains.
Make sure and measure with a multimeter that all transformer covers get grounded via the attaching screws. Also check the output voltage with the new chokes, their DCR is around 500ohm and stock chokes have around 1kohm IIRC. I suggest to get rid of the regulator and the other silicon the coincident has in the anode supply, and just make it as a regular CLCLCLC-supply. The ripple of this supply with three 30H Noguchi chokes is so small (couple uV or even pV class) that any active regulator itself makes more noise than the ripple is (I presume).
Got finished with the Allnic, very good.
For some reason grounding the "center pins" of the sockets resulted in massive contact transients when changing between MM1/MM2 etc. inputs and crazy noise on MC inputs. I though it should reduce it. At least it went away straight away when I disconnected the ground leads so I cannot think of any other reason. The ground leads are still visible in the picture.
I'm still wondering how to execute the changing of the cartridge input load resistors. Originally there is a switch for them to change between 10k/20k/30k/47k. Maybe I could live with a direct soldered (bypassing the switch) 47k res like this guy had done: Allnic H3000 naked z-foil vishay tweak.
But 2W AN non-mag tant instead of Z-foil.
For MC I would still have four load options (278Ω, 117Ω, 70Ω and 29Ω) because the Allnic's SUT has 4 different step-up ratios (22dB/26dB/28dB/32dB). I quess that's enough.
For some reason grounding the "center pins" of the sockets resulted in massive contact transients when changing between MM1/MM2 etc. inputs and crazy noise on MC inputs. I though it should reduce it. At least it went away straight away when I disconnected the ground leads so I cannot think of any other reason. The ground leads are still visible in the picture.
I'm still wondering how to execute the changing of the cartridge input load resistors. Originally there is a switch for them to change between 10k/20k/30k/47k. Maybe I could live with a direct soldered (bypassing the switch) 47k res like this guy had done: Allnic H3000 naked z-foil vishay tweak.
But 2W AN non-mag tant instead of Z-foil.
For MC I would still have four load options (278Ω, 117Ω, 70Ω and 29Ω) because the Allnic's SUT has 4 different step-up ratios (22dB/26dB/28dB/32dB). I quess that's enough.
The filament supply of the amp got four new chokes and 150VA/13V transformers replaced the old 40VA/10V temporary transformers I had for the 101D tubes. Now the 28kg beast is ready and identical to the filament supplies of the DAC and pre.
HexFred rectified, regulated, LCL filtered "current drive" supply (choke coupled to the tube) with individual overspecified power transformers. The ripple and noise is in the picovolts class. And what's best, the output voltage is measurable and adjustable from the front panel to try out different but compatible tubes in the equipment.
Filament supply does not get significantly better than this imo.
HexFred rectified, regulated, LCL filtered "current drive" supply (choke coupled to the tube) with individual overspecified power transformers. The ripple and noise is in the picovolts class. And what's best, the output voltage is measurable and adjustable from the front panel to try out different but compatible tubes in the equipment.
Filament supply does not get significantly better than this imo.
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