Active VS Passive Tube Phono: EAR 834P VS Hagerman Cornet - let's analyze them! (part 1)

[@NickP333]

I built a pretty much no expense spared clone of the EAR834p phono stage a few years ago. I added loading plugs, as not all MM carts are happy with 47K. I did a good amount of mods which ended up being excellent upgrades (one to lower the possibility of oscillations) by reading different threads in Lenco heaven. It came out sounding fantastic for MM carts. I now use a Tavish phono stage, because it is able to run my MC carts with ease. I may eventually try adding a SUT to my EAR clone, but I’m enjoying the Tavish (which has a 12AU7 cathode follower) very much as of now. Thanks for getting somewhat in depth regarding phono stages, Janos. I learned so much building my EAR clone, and it took me months to finish, but I wanted everything to be perfect. Thanks again!

[@realworldaudio]

Awesome! :) I agree, the 47K is just a good ballpark, the exact load depends not only on the cartridge, but needs to be matched for the entire system. I'm glad that you have such a great time with this superb phono. :)

[@NickP333]

@@realworldaudio I don’t think I’ve ever run into a MM cart that recommend anything but a loading of 47K. Is your experience different?

[@phillipherring659]

Awesome video, thanks for sharing your knowledge. May I ask you a question: can you calculate the input overload of the Cornet and the 834P just by looking at their schematics? Your answer will be much appreciated.

[@realworldaudio]

No, not really. The manufacturers specify the maximum input voltage, that should give a hint about it. Without additional information, most phono stages are built to handle 5mV, and usually are OK with 7-8mV without distortion. It's a good general rule to plan for 5mV for the input to the phono stage. (And it will also be able to handle records that were cut with high dynamic range, and have 8-9mV signals as well - these records are rare, but they exist.) While the phono stages would be more likely OK with a 7-8mV input, but in that case these higher cut records would give 10+mV, almost certainly clipping the phono stage. Although I can add that the Cornet has tremendous headroom, will be fine even with that.

[@phillipherring659]

Thanks for the informative answer. I noticed in the manual the input overload for the Cornet is a rather large 250mv, many multiples over what a cartridge can produce. I believe this 250mv number is being derived from the calculated input overload of the second 12ax7 gain stage. Working backwards, I think the second gain stage has been biased with a peak voltage of 1.5 volts, which means the 1st stage 12ax7 - (because of the mix of resistors and capacitors has a reduced mu of 60x) - and can’t be fed more than 250mv? (250mv X 60 = 1.5v) I just do not know how to do the proper math to prove this theory. Do you know if I am thinking about this in the correct manner?

[@realworldaudio]

@@phillipherring659 You are correct, the bias voltage shows the overload limit for any given stage. However, there are more thing to consider about sound, not just ovrload. As the signal gets excessively large, there's much greater stain on the power supply, and sound will get compromised (compressed dynamics and power handling) well before overload is reached. In my experience the Cornet loves 10-15mV input peaks, but would not task it with anything silly or unrealistic. Also, anything above 3V-4V out will massively overload the following stage. You get 2V out with 5mV in - a 20mV input would give a monster 8V out, that would clip any amplifier so badly it would go up in smoke on the spot.

[@phillipherring659]

Excellent points to consider, thanks for taking the time to answer

[@realworldaudio]

@@phillipherring659 You are welcome! Long story short is that the Cornet can handle anything available on the market without the slightest stress. I suspect the 834P has a decent amount of headroom as well, but I have no personal experience with that.

[@solarman30]

Hi Janos. Just a point of correction, the EAR clone does not use 65v on the input tube 's plate. I have an EAR 834 clone on my bench right now, so I performed some measurements. V1 has 100v on the plate. V2 has 122v on it's plate. The cathode follower has 293v on the plate. My B+ sits at 295v, and the heaters (DC) are biased up 38v DC to prevent cathode / heater problems. Love your content! Thank you for the videos. Dan

[@realworldaudio]

Thank you Dan for the info, wonderful! Indeed, yes, those plate voltages are a sweet spot for good sound & long tube life for this tube;

[@EduardBroekman]

Very nice to see such a review of different approaches for a phono stage. On your comments with grid resistors.. any idea why transformer coupling was avoided - just costs? I have never designed a phono stage, but with input transformers I can typically eliminate grid resistors throughout and apply fixed bias via the transformer and avoid bypass capacitors. Thomas Mayer once mentioned that he can often solve the resonance problem elsewhere in the circuit, which turned me away from the textbook approach to finding alternatives that have synergies so I'm not needing to add components for each problem. It can be as simple as taking a variant of a tube that removes the oscillation problem just by itself.

[@realworldaudio]

Yes, cost is a huge issue not to use transformers in phono circuits. Another issue is to keep the signal path as short as possible, and that is hard with a transformer. Third is that magnetic shielding of the transformer is a big issue, as the signal levels are so tiny. Fourth, as signal levels are so tiny, you are forced to use exotica laminations, and you loose a lot of low level detail if the windings are copper and not silver. Fifth, we have to calculate with the inductance / capacitance / resistance network that a transformer creates, making RIAA EQ calculations extremely difficult. These are the doable ways to improve the signal path: 1. lower the resistor values (however, that means the capacitors will go up in value - but that's not such a big issue now) 2. using a choke instead of a resistor. These latter are the "LCR" phono stages and they come with a major cost increase... So, I went for choice #1, and that's what the Cornet does - 10K is the highest R in the signal path vs the 2M in the EAR, and 100K+ values seen in most phono stages.

[@EduardBroekman]

@@realworldaudio Much food for thought - thank you. I general got good gains by removing components or using better components but I'll take your comments and strategies with me in the future - I can see application in a tube xo :) I saw in several of Sakuma's phono amps an amplification stage before using any transformer and then always a passive LCR network. But there's a total absence of R in the direct signal path and always high wattage R to probably reduce noise. My gut sense so far has been that the longer signal path of in quality (Lundahl in my case) transformers affects tone less, has less colouration - despite perhaps dropping detail. This may be a case of where gains need to be made?

[@slistone1940]

Does the cornet have dials or switches for gain? Mc/mm?

[@realworldaudio]

No, it does not have any adjustments. It's MM only.

[@slistone1940]

⁠ how does it do with isolation? I read on some forums that people complain about a hum? Can’t have other components too close?

[@Migkiller1971]

I am So Bored and haven't built or upgraded any of my equipment in a long time. I have a hagerman cornet 2, Is there any way to add a filter choke to it? Would it be an improvement? I think the trumpet phono stage has a filter Choke. Thanks!

[@frankgeeraerts6243]

Good choice for 12AX7 INPUT tube........... : ECC803S Telefunken E83CC TESLA ( not JJ !!!! ) ..same as Telefunken with frame grid......... ECC808 ...........very low noise version, symetrical pin-out ! and ..........very rare but a marvelous tube. Van der Veen ( NL ) prefers 12AU7 instead of the ECC83 as an input tube...... ECC88 ( nos with damper mica fingers on the cathodes ) is also a good choice..... best versions are the CCA and the ECC188 .....AVOID the popular 6922/E88CC..........they do

[@NickP333]

Exactly, Frank. A lot of MM carts work better with different values besides 47K. I built an EAR clone, but added loading plugs for that exact reason.

[@frankgeeraerts6243]

@@NickP333 Hello Nick , thank you for your reply..t is also my experience and that from others that it is better NOt to use an addional small cap on the input .Vand der veen compared 12AXè versus 12AU7 and found it was more musical;There are also very good ECC82's....I like especially the 5814A black plates from RCA ( triple mica ) and the ECC82 flat plates from telefunken..

[@realworldaudio]

@@frankgeeraerts6243 Hi Frank, I second it, any additional loading capacitance for the input just removes too much HF information.... ;

[@garyvitrano8362]

I am currently running my EAR 834P with 12ax7A in the first two positions and a 6201 (12at7wa) in the third position (cathode follower), do you think this is okay? I’ve also seen where people use a 12au7 in the third position, what are your thoughts on this?

[@realworldaudio]

Hi Gary, it should be all right. One thing to look out for is that the 12at7s draw double heater current than the 12ax7s. (So total heater current draw for all tubes is 133%) If the filament transformer is happy with it, then you are fine. The 12at7s have much lower Rp than the 12ax7, while having a gain high enough. The 6201 should give a more relaxed, mature sound than the 12ax7. ; ) Have fun! Janos

[@haman-dex]

Do you have any experience with the OTOMON amplifiers by Ken Useugi? I belive these are the best tube amplifiers in the world. I love watching your videos!

[@varindersingh7309]

What amps of Ken you have heard Dejan?

[@realworldaudio]

No, I have only seen Ken's amplifiers on youtube... Briefly: I love them! He really knows what he is doing, I would recommend pretty much any of his amplifiers, provided you have matching loudspeakers. (Harder for the 71A, easier to match speakers with the transmitter tube ones.)

[@haman-dex]

@@varindersingh7309 I've heard 71a, 45 and vt62. 71a I heard on my JBL horn system. The other two at friends homes.

[@haman-dex]

@@realworldaudio As I learned and heard they are of course all different.. It would be very interesting to see some serious reviews, comparing, sound demos ... There is none of this on YT . I would really love to hear your impressions on those masterpieces.

[@varindersingh7309]

@@haman-dex ok .. how they fair against top stuff like Audionote , Thoress ? Any idea

[@amosscattergood1722]

Thoughts on original Cornet vs Cornet 3?

[@realworldaudio]

Hard to say as my original Cornet is DIY build from kit, and it can be greatly varied depending on how you build it. Mine is super pimped out, and it has jumped up a few categories. However, comparing stock Cornet builds, the Cornet 3 is better. Even though it has SMPS supply, it does not seem to affect the sound badly, and it's a very natural sounding phono. The original Cornet has the advantage that the bigger chassis allows upgrades, which will significantly up the level. So, if one wants to upgrade/DIY it, the original Cornet is a better choice. When one wants a unit and plug and play, Cornet 3 would be my recommendation.

[@amosscattergood1722]

Thank you! Have a Bugle and looking to upgrade. I appreciate your content and perspective!

[@terrywho22]

@@amosscattergood1722 I'm a bit late to the party, but have you checked out the audio karma thread on the Bugle? Hagerman Audio also now offers a plug-in opamp upgrade for the Bugle which makes a huge difference as well. If you already have the Cornet, let me know how it compares. Cheers!

[@terrywho22]

@@amosscattergood1722 Have you looked at the Hagerman Bugle upgrade thread on audio karma? There are a few different levels of upgrade and the results are amazing.

[@hoobsgroove]

not sure that's the same one but I didn't think the specs that good! 87 DB n/s valve shouldn't be used in a phono stage produces too much background noise, you want something with 105 + DB noise floor solid-state at least in the first stage.

[@realworldaudio]

The 12ax7/ecc83 tube family covers a wide expanse of tube quality, many dozens of tube types fit here. You can find ones that are quite mediocre, and ones that are stellar. In my Hagerman phonos (both Cornet and Violin) any 12ax7/ecc83 variant I have tried was dead quiet, even with 102dB/Wm efficient speakers. I find it very odd practice that they give a set s/n value to a tube type, as the s/n wildly depends on heater supply and operating point. However it's true, there are way quieter tubes than the 12ax7 family... for example the CV5311... Yet, the 12ax7 is the most ubiquitous, most easily accessible tube ever, so a good choice for a product that is built to last decades. Also, by tube rolling you can wildly alter the tone of the phono stage, so very wide margin for customizing it to the flavor you prefer.

[@hoobsgroove]

@@realworldaudio not sure what you trying to say! I was talking about the whole circuit in general not the tube what about the seven something serious tube used for microphones, are they any good, I would have thought they'd make a good candidate.

[@realworldaudio]

@@hoobsgroove I see, you were referring to the circuitry. In my experience tube phono stages are quiet enough for the purpose - for example, when I listen to a digitally recorded LP through my Hagerman Violin, it is as quiet as the CD version on the CD player, zero clue you are listening to vinyl. The S/N ratings for phono stages and digital sources cannot be compared, as digital and tube S/N ratings are not equivalent by a very long shot. That's because N floor for digital is a HARD barrier, even getting close to it we start to have problems with signal integrity. With analog S/N there is no compromising the signal as we near the N floor. Even more, we hear below the noise floor which happens to be white noise. The human brain uses white noise as a calibration to calculate SPL. We do this naturally, as white/pink noise ALWAYS surrounds us in nature - that's how our brain developped, to use it as a cueing mechanism. With digital, the noise floor is something very nasty, a very high frequency hash, and the missing white/pink noise floor does not allow the brain to properly calculate SPL and dynamics. Special tubes, like the one used in Neumann U47, are not used in the Cornet or the EAR, because those are so expensive that they would elevate the costs to a very, very different land... use a set of those, and you enter the world of phono stages sold at 30-50,000$; ) Going back to S/N... between tubes and transistors... for transistors the dynamic range is much poorer, linearity poorer, and low level resolution poorer. I abandoned using them for audio purposes, as they do not yield acceptable tonality for my ears. The harmonic spectrum of solid state devices is not suitable for reproducing acoustic instruments. Others might have different opinions.

[@EduardBroekman]

Just for some perspective, I'd first consider how much S/N your listening environment has. If you're listening at 70dB and your background noise is 40dB.. and assuming that your components are fairly well matched, all such S/N specs become entirely irrelevant since your environment is nowhere close in S/N. Very few have a listening environment with 87dB headroom. Plus I don't think it would matter much having a 70dB S/N phono stage to play a 45dB S/N LP... In conclusion, I'd go for what sounds good first :-)

[@hoobsgroove]

@@EduardBroekman yes it's not that tho! it's the detail on the record can be at a very low levels, if you got a phono stage with a hi ish noise floor You're going to lose that micro detail from the record or not as match dynamically. that's why you want a phono stage with over 103 db ideally and high accurate riaa.