Lundahl MC Phono Step-Up Transformer Kit - DIY Tips & First Impressions
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- Опубликовано: 15 сен 2024
- This is a low noise, passive amplifier that provides gain to the signal of a Moving Coil phono cartridge so that you can use a Moving Magnet phono pre-amp. With a highly resolving record playback system, this device may reveal more detail embedded in the record grooves and provide a more engaging listening experience.
For the health and safety of my family during Permanent Covid, I place masks over my phono cartridges, between my RCA cables and their racist input jacks, and of course over my speakers. I find that my system sound becomes more clear and holistically impedance-agnostic. My connected PC no longer suffers from viruses. This is both passive and transformational. Your mask on this video is inspiring and clarifying. Thank you for showing us the way. Please be safe as we work our way through the coming decades of this health emergency. Thank you.
Very thoughtful comments. Maybe someone has proven Covid cannot be transmitted over EMF/RF radio waves or thru electrons via transformers.
Did you try playing it with mask on cartridge, thats supposed to improve sonics and match impedances.
I know I’m a bit late to this party, but one could also use a high quality 1K or 2K stereo potentiometer or stepped attenuator instead of loading resistors, so you’re able to dial in the right resistive load in real time. Thanks for the excellent vid 🔊😊🎶
Great video and information, many thanks. I am just about to order a Lundahl SUT kit so this video was super helpful.
Thanks. My SUT helped eliminate noise from the cartridge/turntable, i.e. greater Signal/Noise ratio.
you mentioned that output was mono when you removed the ground shorts. that would indicate one of your grounds is open on the interconnects or the headshell
Thanks. I'll check that out. No noise or hum with the ground straps in place tho.
Do you also have stepup transformers for low output dacs without an I/V stage?
Good idea. Do they exist?
@@AudioTnT I mean lower than the standard 2 Volts. Mine outputs about 0,8 Volts, exactly due to the absence of an opamp and a usual i/v stage at the output. It's an I output dac directly from the dac chip, as direct it can be. Old, NOS design, based on the Phillips 1545A chip. Its name is Monica2, by DIYParadise. Excellent sounding after some mods, low output is a problem sometimes (rather few). I think its Vref might be a problem in using an output trafo, as stated in an old diy forum. Another option might be a passive, autoformer based volume control after its own output, with some extra stepup windings. What I meant was the possibility of replacing its output cap with an output transformer. A 600ohm 1:1 may be used in V output dacs or CD players of normal output, but I'd prefer 1:2 or 1:4, if it can be done for i output too.
@fullranger3435 Very interesting. Would output impedance of Dac chip be similar to a phono cart? I'm using dual balanced DACs of Eversolo DmpA6 via XLR to a Topping Pre90 for lower THD and higher SINAD. A passive approach might be even better...
@@AudioTnT I don't know that but I don't think so. I don't know what its output impedance is. I only know that, since I use it with a ladder stepped attenuator before the amp, this is preferred to be of around 20Kohm input impedance rather, than the usual 50 or 100Kohm pots. Mine is around 25. Seems that this direct configuration prefers lower input impedances in the next stage. So I guess a usual 600 ohm output trafo in the place of its output cap would be OK, if no other problem to be solved. There is a special tube output stage built, designed and highly recommended by its creator and others but I don't want to go active, although "lampization" has its strong points. I don't miss anything in my present "ultra pure" configuration, except perhaps some extra drive in the lows, sometimes.
Thanks a lot. What is your impression regarding sound improvement? S/N ratio should be improved in any case, but what about a sound? As far as I understand, you were just reading the instruction in the end of the video, where possible sound improvements were mentioned.
The video was done right after I put kit together. To my ears, I found the difference to be subtle. Reducing hum from cartridge/turntable using different grounding options on Lundahl was biggest benefit for me.
Do you have any idea where to get these kits? I cant find anyone who sellls the SUT kits. If i can figure out the details I need I can boost the voltage on my cartridge from .4 mv to 4 mv and input on MM input on a Luxman C35 MK III preamp, which is all tubes, no transistors! Input sensitivity is 1.5 mV and distortion is .06 % at 2 volts output. Imagine that if you will, Luhndal transformer to boost the voltage 10 times to 4 mV. The bad part is not great signal to noise ratio with only 64 db on Luxman pream phono input. K&K audio could only make it work with a FET input after step up transformer in there maxxed out phono preamps, which unfortunately are unavailable.
I bought mine from VK Music. K&K Audio should be able to offer a kit. Mine uses Lundahl LL1931 w 8/16 X switchable gain. LL1971 gives 12/24X; LL1941 gives 16/32X. My SUT feeds a Sunvalley EQ 1616D all tube phono stage w hi/low gain for MM/MC sections. It has just enough gain to drive an Elekit 300B power amp. I use Hana EL and Denon DL 103 MC carts. Hope that helps.
Did you check your transformers for ringing? I Did some research and found putting a resistor on the secondary to match impedance is not how to do it. Were not trying to match impedance, increasing the voltage is what we need to do. 100 to 400 ohms will cause most voltage to appear accross that resistence instead of the 20 ohms output impedance. Whats needed on the secondary is a rc to filter out ringing and has to be done with a signal generator at 1khz, and oscilloscope. K&K Audio does not explain this, and the kits dont tell you this. Putting a resistor to match impedance is not correct. If it matches the impedance of the output then you will have two resistors in series dividing the voltage equally, transferring half the voltage to the primary. You want all the voltage to reach the primary, I though you might want to know this.
Putting an RC in series across the secondary does not effect loading on the secondary, just resistor does. The more loading you apply on the secondary reduces the voltage level at the secondary. You don't want to do this with MC.The RC has to be setup so it provides a path for the oscillations or ringing to ground, it's a filter at whatever frequency ringing is and it dampens out the ringing to ground. And the level of voltage will not drop at the secondary. This means a perfect square wave will be presented, of 1 khz, and should also be checked at 10khz square wave. The ringing frequency happens because of the resonance caused by capacitance between windings and whatever inductance is present. If you don't care about this than you will be getting more noise as relative to the reduced voltage caused by damping with a resistor.
well, I found a SUT kit after trying to order luhndahl transformers without much success. All the distributers , most listed ones for luhndal I cant order from. I only found 1 place I could order from and its about a month waiting time. So, amazingly I found an assembled SUT, similar to yours , but wider, on ebay.. It has L9226 which has good specs and gain of 10. You dont put load resistors on a SUT. With a phono cartridge, matching impedance doesnt work. The guy that made mine I had him put an RC compensation across secondary to reduce high frequency ringing on secondary of SUT., while inputing 1khz square wave at primary. Load resistors reduce voltage on secondary. I dont have load resistors. Reflected impedance is 470 ohms, which is more than the recommended 100 ohms, i allready listened to it through an all tube preamp for 100 % tube amplification from cartridge to speakers. I have MC with output impedance of 20 ohms. most MC are fairly low. loading the secondary down reduces your inpuit impedance. You have a voltage divider at the input and when you reduce the input impedance less voltage will appear at the primary. you would be better at adding resistance at the input loop, reducing voltage at input of transformer to reduce output if its too high. Anything greater than 10 gain adds noise. 5mV is limit at phono input. My preamp phono stage has sensitivity of 2.5 mV. i have a hum problem but Im working on that now. im getting a Denon dp 500m was looks fairly decent. It has jacks at the back of it so I can shorten interconects to SUT. i ordered cables that are 1 foot long each because I have a distance from TT to preamp of 2 feet. I was looking at Your tube preamp and amp. Like your setup. i saw the schematic of your preamp. i think you got 300b SET. I prefer 300 B push-pull class A - AB
Great video. Have you used or compared other SUT before deciding on the Lundahl Transformers? If so, were the differences? Thank you
No, this SUT was recommended by the dealer that sold me the Sunvalley phono stage. The reviewers at Stereophile seem to like SUTs over active amplification for moving coil carts. My SUT can isolate grounding and hum problems but my ears can't hear a difference.
@@AudioTnT Where can I get the Lundahl kit? I'm in BC Canada. Thank you
@@normloo1590 I bought mine from VKMusic (Victor Kung) in Coquitlam. Also avail from K&K Audio in US. Very easy to deal with.
Why are you wearing a mask indoors?
Keeping u safe from Covid. Sorry that's all u got out of my video.