My lineout trafos are these: FM-10K-600CT/??????????? [FM-10K-600CT] - 19,660? : Zen Cart [????] : The Art of E-commerce
Ordered through them: Japanese Proxy Purchase Service - J-goods
I remove the steel chassis and pot them with rock pebbles (quarz + magmatic soft/"lossy" rocks) and epoxy.
Pretty sure everybody does not see this pic, please try Chrome to see it:
Thanks for the info, I was able to see the image. I will order the transformers today
You posted that you were using them in a 4:1 configuration, are you able to clarify?
Thanks again Legis, I am sure that you are the only person to modify the pre to this extent.
Cheers
Greg
The mentioned 4:1 transformation ratio was just to give an idea of the transformer (electrically), how it affects the output impedance and voltage. 4:1 is the normal ratio for the Noguchi when the primaries are in series.
These transformer covers for potting them (+ salvage the bottom plates from Coincident's stock transformers for attaching). The black parts are identical to stock covers: ER10 90x80xH100mm
Hi Legis,
The regs arrived today and I have installed them, unfortunately there is not enough headroom on the original power transformer so I will use some spare transformers tomorrow.
I see that the original schematic uses a balanced bias. I think according to your posts you have changed this to a +filament bias? Do you remember what value resistor you ended up with? Next to get the transformers etc.
Cheers
Greg
The regs arrived today and I have installed them, unfortunately there is not enough headroom on the original power transformer so I will use some spare transformers tomorrow.
I see that the original schematic uses a balanced bias. I think according to your posts you have changed this to a +filament bias? Do you remember what value resistor you ended up with? Next to get the transformers etc.
Cheers
Greg
Hi, I connect the cathode res to minus/negative side of the heater, not positive. The triode symbol of the schematic editor is confusing/wrong for a DHT. Original cathode res is 1,5k, I use 1k (2W AN non-magnetic tant) in every 101D stage.
Thanks Legis, I take it that you bypass the 1k on the negative with a cap. Just to confirm the direction and size of the polarised cap on the negative side of the heater to ground?
This pre is starting to sing. I can't wait to get the transformers. I have now implemented the Germaniun Diodes etc. huge difference. One challenge is that they seem to keep blowing/failing causing the fuse to go.
Exciting times thanks to you.
This pre is starting to sing. I can't wait to get the transformers. I have now implemented the Germaniun Diodes etc. huge difference. One challenge is that they seem to keep blowing/failing causing the fuse to go.
Exciting times thanks to you.
What 101D tubes you have?
Let me know how the Black Gate N and AN Kaisei differ in sound once/if you try the Kaisei.
A surprise is waiting after you change the J&K TVC's and Noguchi output trafos. TVC's are pain in the a** to solder. I tried it at first with a solid core Duelund hook up but had to go with multi stranded Duelund DCA20GA after ~10th broken wire.
Let me know how the Black Gate N and AN Kaisei differ in sound once/if you try the Kaisei.
A surprise is waiting after you change the J&K TVC's and Noguchi output trafos. TVC's are pain in the a** to solder. I tried it at first with a solid core Duelund hook up but had to go with multi stranded Duelund DCA20GA after ~10th broken wire.
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I have the stock 101d's, Psvane 1:1 replicas and the TJ mesh plates.
I will order some AN Kaisei's to compare, I will let you know.
I am sure that the transformers will make a big difference, I can't wait. I am going to rewire with the Duelund 16 and 20awg. I am using some Russian wire wound resistors for the RK based on the experience on Bartola tubes blog and his 201a DHT pre. I will be ordering some AN 2w tants and some AN 2w silver Tants to compare. I use some 2w silvers in my line magnetic 503pa amps. I am thinking of upgrading the interstage and output transformers.....
Just have to figure out what I will need.
I also have a pair of Cunningham 301a's here that are itching to be implemented into the pre
I will order some AN Kaisei's to compare, I will let you know.
I am sure that the transformers will make a big difference, I can't wait. I am going to rewire with the Duelund 16 and 20awg. I am using some Russian wire wound resistors for the RK based on the experience on Bartola tubes blog and his 201a DHT pre. I will be ordering some AN 2w tants and some AN 2w silver Tants to compare. I use some 2w silvers in my line magnetic 503pa amps. I am thinking of upgrading the interstage and output transformers.....
Just have to figure out what I will need.
I also have a pair of Cunningham 301a's here that are itching to be implemented into the pre
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Hi Legis,
If there is one thing that I really don't enjoy then it is wiring TVC's! I wired up the Intact Audio TVC's..... big improvement over the stock ones. I was surprised to see how small the originals were. I am still waiting on the Nogochi output transformers and chokes to arrive.
What 101d's are you using? I seem to go between the TJ mesh plates and the Pavane 1:1's
If there is one thing that I really don't enjoy then it is wiring TVC's! I wired up the Intact Audio TVC's..... big improvement over the stock ones. I was surprised to see how small the originals were. I am still waiting on the Nogochi output transformers and chokes to arrive.
What 101d's are you using? I seem to go between the TJ mesh plates and the Pavane 1:1's
When I'm using 101D's it's also usually TJ mesh plate. Im currently running with UX201As. Haven't tried the WE-replica, maybe someday if I get the motivation to try that expensive tube. How would you describe it's sound?
Cheap NOS RCA 12SN7 (12 volt version of 6SN7) wired both triode halves in parallel are good for a budget tubes. Adjustable heater supplies are so handy.
I also hate wiring TVC's, the J&K's took me many, many hours.
I found out a curious phenomenom with tube amplifiers - they seem to expand the Dynamic Range?? See the new thread here (recorded files included): http://www.diyaudio.com/forums/tube...dynamic-range-dr-explanation.html#post5149612
Hi Legis, I have been finalising my order with Jolin at J&K and I have asked them for an exact copy of your tvc's. Are you able to confirm that I would be able to use it in both single ended or balanced input kind of like the stock Coincident configuration? Your help is really appreciated as always.
Yes my TVC's have center tapped primary, so they can also be driven with symmetrical/XLR signal. Also the Noguchi's line output transformers have center tapped secondaries so XLR output is possible.
Thanks for the subjective comments regarding the WE-replicas. My preferences and also system dependancies (like TAD drivers) usually go for more romantic sounding tubes or closer to "best out of both worlds" (like FM 101D/n). I'm all about smooth, toneful, "easy to listen to" sound, which does not forget resolution and other "hifi" stuff. Adjectives are sometimes dangerous since everybody understands them differently, for instance for me the term "smooth" is not lack of resolution or mushy sound etc., just that it mainly lacks "edginess" (which is a very common tonal error in my opinion).
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I agree 100% on tone/smooth especially as we both use horn speakers, it simply has to sound like music especially in this over compressed over engineered music world that we live in.
Currently Jolin is suggesting 1+1:1, that can be configured and better optimized if user wants configurable primary, balanced or single ended. This TVC has dual primaries that can be used in series, parallel, and split (balance). This is good for both balance and SE inputs, and has 2 gain selections for SE.
Still, if we talk about performance, a dedicated SE or balance in transformer will be better compared to configurable version.
Currently Jolin is suggesting 1+1:1, that can be configured and better optimized if user wants configurable primary, balanced or single ended. This TVC has dual primaries that can be used in series, parallel, and split (balance). This is good for both balance and SE inputs, and has 2 gain selections for SE.
Still, if we talk about performance, a dedicated SE or balance in transformer will be better compared to configurable version.
Sound like a plan. I would opt for 0.5+0.5 : 1 so the TVC could be used to step up the voltage 6dB when primaries are connected in parallel.
When you changed the original TVC's to Intact Audio TVC's you also saw how the gain of the pre dropped. There was a step-up transformer prior to the TVC (or after it) at the input. There was also third transformer for the XLR-input IIRC. All three small transformers were inside the same potting enclosure, they were really small.
The gain with 1:1 TVC, 4:1 output transformer and 101D tube in near unity gain, maybe couple of dB's, so the pre acts mainly as a tube buffered volume control without much voltage gain. This is why I would rather opt to get option to step up the voltage 6dB (0.5 + 0.5 : 1) rather than attenuate 6dB (1 + 1 : 1).
Since the Coincident pre has two sets of output RCAs I have also tried it in "passive" setup in the past. I wired the other pair of output RCA's to output the signal right after the TVCs without going through the tube stage and the pre could be left without power like a passive pre. However the tube staged output was so much better in my system than passive output that I later changed the second RCA pair to capacitor coupled output like it is currently. Passive setup had vanishingly low disotrtion and wide bandwidth when only the J&K TVCs were in on the signal path, but tube stage does good things
.Right now I'm thinking if I should also leave the capacitor coupled output option out from my pre and amp. I never use them either as I don't need the gain and transformer coupled sounds better. If I ever needed the gain of cap coupling (+12dB per stage) I could use the cap output in my DAC. I could also transfer the Duelund Cast Cu coupling caps from my amp to my DAC for the only cap output in the system. I just might do this, it simplifies the system further and still leaves one option to get higher gain for low level recordings if ever needed. Oh well...
Ah that makes sense as I had noticed that the gain had dropped with the Slagle tvc's.
Here is a quote from Jolin "We can play with 2 gain settings if you go with 1+1 primary.
In SE, with both in series, you get unity gain (1); with both in parallel, you get 2x the gain. Such design is quite common. The performance will be slightly worse than a dedicated 1:1 but if you do not A-B it and pay special attention, you can hardly hear the difference."
definitely good to get a little headroom.
I soldered in some Seiden selector switches which made a very big difference to the temporary plastic junk that I was using. Now to order the KBG-MN's and Jensens for the Power supply. I am still waiting on my Finemet transformers to arrive at J-Goods.
Interesting re the capacitor coupled output. Are you not using your UX201's anymore? Have you tried them with a transformer coupled output?
Here is a quote from Jolin "We can play with 2 gain settings if you go with 1+1 primary.
In SE, with both in series, you get unity gain (1); with both in parallel, you get 2x the gain. Such design is quite common. The performance will be slightly worse than a dedicated 1:1 but if you do not A-B it and pay special attention, you can hardly hear the difference."
definitely good to get a little headroom.
I soldered in some Seiden selector switches which made a very big difference to the temporary plastic junk that I was using. Now to order the KBG-MN's and Jensens for the Power supply. I am still waiting on my Finemet transformers to arrive at J-Goods.
Interesting re the capacitor coupled output. Are you not using your UX201's anymore? Have you tried them with a transformer coupled output?