You said it well...................input impedance and the marketing trick to sell you a gain stage ( pre-amp = costly) Tube are voltage driven on the control grid ( high impedance ) // grid resistor ( or vol pot ).....transistors are more current driven .........( often with inmut capacitor )...and the resistor is chosen lower for the reasons you mentioned ...but with higher impedance the transformator will have no problem especially on the lower volume settings ! .........and that's where they excel with all those micro information that make the difference between living music , living nature and sterilized milk...... it's those tiny things that make all the difference of being alive versus a static lifeless reproduction ...........it's like the air you breathe.....
In the future I want to upgrade the volume control of my Oto, but this isn’t that simple since it’s a integrated amp. I would like to skip the original potentiometer.. I need to hire a audio pro to do it for me, but I was wondering if you have suggestions? (I have the version Phono Se signature version)
Hi Nick, I'd suggest to change the pot in the Oto to an Audio note tantalum resistor (Actually, one resistor per channel - two total). Bigger wattage, the better, I'd suggest 2W or 1W rated one. The original input impedance of Oto is 100K, but that is because the pots come in 100K. Going a little higher (to 120K-170K) will be of benefit. Keep the two channels as close to each other as possible. The exact value does not matter for starters, but they should be as close to each other. Eg 154.6K - 154.6K. So, if you order a pair of 150K resistors, and you get two 154.6K, that's of absolutely no concern in this application. Insterting the AVC/TVC will be a little tricky, as you need to take signal that feeds the pot, add a pair of interconnects there to feed the AVC / TVC, and then a second pair of interconnects coming back to the OTO to feed those newly installed input resistors. Will also mean you need 2 pairs of RCA jacks and 2 pairs of interconnect cables as well. Quite a bit of surgery!!
hi , would this work with a mcintosh mr 78 tuner? with 600ohm output impedance? and output of 2500mv? running through a unison research s6 integrated with 47kohm input impedance impedance? thanks Brian.
Hi there, I still don't know your name, but you will have to excuse me for that. I saw your video with listener questions on output trafos from Edcor / Hammond etc. Still, If I said that I consider using budget but good transformer in my upcoming build of 300B SET DHT with "Darling amp as pre-stage", would Edcore or Hammond be sensible choices, or too low quality to get very good results? Would you go for any particular model/size for any of them, considering the approx 2*8W ? Cheers, Magnus
Hi Magnus, both the Edcor CXSE series or Hammond 1600 series would be good candidates. (Not the smaller series.) These are 25/30W iron, and they will give you headroom! while more esoteric iron will give more refinement, but they will not give you the headroom nor the apparent power, unless they are also 25-30W rated. So, either of the Edcor/Hammond will play large scale music better than a smaller (7-10W rated) Hashimoto / Tango, which will run out of juice at fortes. - Janos ;
@@realworldaudio Thx, Janos! Again speaking of my upcoming 300B SET build, I got a suggestion to use one cascode wired 6SN7 as pre / driver for each 300B. Do you see any obvious advantages using that idea, instead of using Darling amp as planned so far?
@@vespass225 I never played around with cascode, nor SRPP, as my mentor was dead set against using them. He said that if you want something similar, then have each tube (section) with its own plate load / cathode resistor, they are much happier and more linear compared to srpp / cascode. So, if you go the 6SN7 route, I'd recommend first section DC coupled to second section, each with their respective resistors and set operating points. Also, I'd recommend against sharing the same filament potential between tubes with very different cathode voltages. (Eg one siting at 6VDC and the second at 200VDC, as in a cascode / DC situation.) This introduces stress to the sound. The 6SN7 version will be more dynamic (due to higher gain), but also more colored / less natural sounding. The Darling driven version will have a more pure sound.
@@realworldaudio OK, quite some arguments pointing in the direction of staying on the Darling path then...! Thanks again for extensive and kind answer. Magnus
@Real World Audio Hi really great video and very informative! Would like to ask 2 questions: 1. what brand/model is your smaller AVC that royal thrashes the prometheus audio? 2. My set up is in between your 2 scenarios, which should I choose? My dac is the denafrips terminator which outputs 2.3v at 625 ohms (output impedance), and my amplifiers are cary tube mono blocks of 150k ohm input impedance, and 1v to drive the amplifiers to full power. My power supply at home is 1 circuit to drive all equipment, but I do intend to buy a power distributer/conditioner one day for better power. Which would you recommend? Thanks!
My AVC is unique, it has no brand - it's my design, and I had DPA (a Hungarian master transformer maker) wind it for me. Sadly, I have had feebdack that Promitheus audio cannot fulfill TVC orders anymore, they got so overwhelmed with orders. I'd recommend trying other companies, S&B is one that makes TVCs. (Much more expensive than Promitheus ; (...
Some solutions are the regular cathode follower.......but there are other options/solutions like the WHITE cathode follower and also the genius " PARALLEL SRPP. " ........
It will work well with the XLR, but with RCA only with mid to low volumes, at full volume noticeable bass cut. Also, think of the gain as well, the TVC does not add any gain, so you if your amp has an regular input sensitivity of 1.5 -2V, then your DACs XLR output is insufficient. Briefly, it will not work, unless amps input sensitivity is 0.7V or lower.
@@listopad44 The it will be able to drive the amp to full output. Just keep in mind that it will not be able to increase volume for quiet sources, it can only attenuate but does not provide gain.
@@realworldaudio Thank you very much for your answers. Usually I listen no more than at 50% of full power (40 W, EL34 PP amp). That is why I need a good passive preamp.
Luckily I had a glimpse of it in my mailbox; ). The cap they are referring to: some solid state amps, preamps (even some vintage tube gear) have an input capacitor to help break ground loop issues. (A sign that the units grounding system could use development.) An inductor (AVC/TVC) and the capacitor form a low-pass second order filter. In similar cases it is better to get rid of the capacitor and fix the units ground issues, as the cap is always cutting into low level information, presents bass loss and phase shift, plus adds high frequency resonances. Although I would not be so alarmed by their findings, 20kHz was 1dB down ; )..
@@realworldaudio many thanks for the explanation :-) I was thinking the cap value could make the issue worst than 1db so got worried :-) I was planning on use it with a capacitor coupled pre amp. Could this also be an issue or just the capacitor in the power amp? In the power amp, the cap would be after the input resistor (it is called C3 in the "amp camp" amp). Is this cap also to break ground loops? Or such caps to break ground loops are always right at the input? Sorry as you see still quite a noob when it comes to circuits. ☺️
@@Thiago_S.. The cap is there to protect the device from possible DC in the input. If the source is properly built, there should be no DC, but you never know and companies often resort to a decoupling cap for extra protection. The resistor is part of the network, would need it regardless the cap.
Ps audio...? what's the PS audio gear I think you can call a autoformer a passive preamp that is what really it is a selector and volume have you thought about using a di box what converts high impedance into low impedance and unbalanced into balanced really you want to get off the grid if you want pure Power using a pure sine wave 2400w+ DC to AC converter ideally at 48 volt lithium phosphate batteries 200ah, you'll probably be alright at 24-volt 200ah. converting it to 230v and then using an isolation transformer step in it down to your home voltage this is not expensive should be able to do it for no more than $900. Or as I suggested before having a power bank of AC power capacitors that could be run from just site Transformers
I think all their products use this technology (BHK preamp for example). Are you thinking of separate box for each channel? The most practical approach would be what Expressive Technologies uses for their phono step up transformer: single big box, but each transformer has its own separate copper shielding inside that box. (Basically, two copper boxes within a big steel box - making their phono step up unit heavier than most amplifiers ; ). In a home approach: copper mesh instead of solid copper, and wooden box would be easier to make and just as good. Indeed, battery power & inverter: tried it out, and works extremely well with digital source, but you need an outstanding inverter for tube amps. The inverter sine wave is very far from perfect wave - good enough for low voltage applications like CD and solid state amps, but stepping up the choppy waves for tube amps - made the high voltage PTs buzz like there's no tomorrow.
Another argument for SET with low or non-existent NFB..........they may have some distortion on the higher output levels but on the micro detail output distortion as low as 0.1 and even LOWER distortion........heavily corrected solid state has what they call in french : " DISTORTION DUR !!! "....high distortion on very low levels and extreme low on higher output ..........together with different distortion figures for different frequencies and volume levels...........the ear ( your ear is very sensitive to these alterations !!!!!!!!!!!!!!!!!!) so is your soul experiencing those problems and it is a source of listening fatigue on so called and some of those glorified high quality high end audio and high price super systems..........
Bullseye! ; _) The brain is acutely sensitive to changes in distortion characteristics. After all these decades of research it is really annoying that most companies are hiding behind the irrelevant aspects of measurements. Well, often, it's the only thing that sells a product, but then, what's the purpose, really. It all comes down to lack of education, lack of purpose, lack of integrity.
@@realworldaudio Same happens with the sheep in this society.....totally brainwashed and amused to death ( Roger Waters ).................and no o,ne can argue with the stupidity of belief systems created by media and continuous propaganda. Think for yourself is now the enemy of the state.............. Dark ages coming.....but there's still music for the soul......
