Recommendation for tube preamp
Hi, all. Initially I was going to ask, which would you rather own – Audio Research LS2B or (BAT) VK-3i? But realized I’m sure there are plenty of other tube options. As you can gather, I’m looking at around $2000 range. It will be driving ML 27.5 amp, which is partly why I’m looking specifically at balanced options. But I guess there’s no harm in using unbalanced>balanced cables? I listen mostly to jazz on vinyl, so I enjoy the details but not to clinical levels where it’s dry. I want warmth. Fine with a phono stage included, but not needed.
Appreciate any insight. Thanks.
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@hoytis When people ask me about tube preamps in this range, I don’t hesitate to suggest the PS Audio BHK Preamp. You can get them used for around $3200, and you can then invest a little bit into aftermarket tubes (the Brimar CV4003 are excellent in this unit, along with a few others) and a quality fuse (if you believe in them, as I do). Fully dialed in, I’ve heard the BHK perform against preamps twice its retail price. In full disclosure, I am a dealer for many high end brands, but I have never had a professional affiliation with PS Audio. I was only a user of some of their products earlier in my audiophile journey. It took a $20K preamp to truly beat the BHK with the way two of them were dialed in to separate systems at separate times. |
I have had great experiences with Audio Research over the past several years. I’ve always been curious about Conrad Johnson but haven’t ever heard any of their products. While the recommendations of an LS28 or REF 6 are great they don’t seem realistic for you since you were hoping to stay around $2k. For that budget, I believe the LS 17SE would be a good move. There is actually one on USAM now that has been there for about 3 months. Asking 2100 and I bet you could get it for around 1800. While I never had that model, it has maintained a great reputation and will not likely ever go below that value for one in good condition. If you fall in love with it, then maybe you can go all the way up to a REF 6 next. They are quite impressive and can be found for about $7000. I think they are the sweet spot for value right now. The REF 3 are around $4000 and pretty outdated. The REF 5SE still bring around $5500 so for the extra you can get the latest design and modern aesthetics. Again, I doubt the value of a REF 6 will ever drop that much. Good luck! |
Geez, Ref 6 is pretty uncolored and clean for a tube pre. 6H30 are generally the cleanest sounding tubes, and Ref 6 is an excellent implementation of them. |
@jlbkmb1958 In a phono section the equalization can be in a feedback loop or can be independent of feedback, the latter of which is a resistor/capacitor network which imposes the proper EQ curve as the signal passes through it; this is simply known as ’passive’ as opposed to ’active’ when the EQ is in a feedback loop. |
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Get a used ARC REF 6. A truly excellent tube pre, that in my system towered above the ARC LS28SE that I tested. I skipped the preamp altogether with my MSB DAC direct to the amp, but then tried the LS28SE on loan. A very slight improvement over DAC direct, but not nearly worth the price for that minor if any improvement. Took a leap and went to a used REF 6. Now that was the ticket. It did everything significantly better than the LS28SE or DAC to amp. It was a real and solid improvement. Added a Shunyata Alpha v1 power cord and yet another step up. In short, I highly recommend the ARC REF 6 — well worth the extra money over the LS28SE. |
It means resistors and capacitors. NO tubes, transistors, or integrated circuits that require a separate power rail to operate.
@jlbkmb1958 I’m not sure where you got the idea that a balanced phono stage requires solid state components - that’s the first time I’ve ever heard such an assertion. As already mentioned, there are examples of balanced tube phono stages with no solid-state components, and some have been around quite a while! What you will see, in some of those, is a Step-up Transformer to provide extra MC gain. That's another kind of passive component (inductor). |
@jlbkmb1958 The tubes we use are 12AT7s, which have two triodes inside a single glass envelope. The input signal is applied through an XLR connection. The input 12AT7 tube is arranged as a differential amplifier. A differential amplifier gets its name from the fact that it only amplifies what is different between its two inputs. So we use the two sections of a 12AT7 as the differential amplifier; the input signal (+ and - of the cartridge) is applied to the two grids. The output of the tube sections is a balanced signal like the input but larger. It directly drives the cathodes of another 12AT7. So the two 12AT7s together form both a differential amplifier as well as a cascode amplifier. Most of the gain we get occurs in this circuit. The two plates of the 2nd 12AT7 then drive the passive equalization circuit; that in turn is applied via a pair of matched coupling caps to the grids of a 3rd 12AT7, also arranged as a differential amplifier. Its output is then connected to the output of the phono section thru a pair of matched coupling caps. To make the circuit work we use a plus and minus high Voltage power supply. No semiconductors in the signal path. You don't need semiconductors to be balanced, differential or both. That quality exists independently of tube or solid state. Our phono section was the first balanced differential phono section regardless of solid state or tube to be in regular production. |
I've had my ML 27.5 (and ML 23) for about twenty years now, but it has been sitting idle in a cabinet for several years since going all in on Conrad Johnson. For many years the ML 27.5 was fed by a Sonic Frontiers SFL-2 double chassis preamp. Connections were made via XLR cables and the sound was wonderful. After acquiring my CJ GAT S1, I briefly used that in place of the SF pre and it was excellent as well until buying CJ LP275M mono blocks. Remember, if you go CJ for a preamp, you will need the Camac connectors to get the RCA cables to feed into the ML amp. |
@jlbkmb1958 Yes. The first balanced tube phono sections were made by Atma-Sphere in 1989.
\I'm confused. How do the design a balanced phono stage without any solid state components in the signal path? |
@jlbkmb1958 Yes. The first balanced tube phono sections were made by Atma-Sphere in 1989. |
I would suggest you shall look into the Raven preamp by Lynn Olsen. Lot of information from this post:- https://forum.audiogon.com/discussions/spatial-audio-raven-preamp |
I owned a BAT VK-5i ages ago; did not like it. It was also hell finding 6922 tubes quiet enough to use. Each time a 5i comes up for sale I’m gob-smacked to see its ask price close to what I paid 18 years ago. I’ve owned so much wonderful gear, far superior, that depreciates like a rock off a cliff and somehow this 5i still commands good money - makes no sense to me! If looking at BAT at least go for a 6H30 model - those are great preamp tubes. 6922 are a PITA. Had an older hybrid ARC preamp (think SP-9) in a shootout some years ago - it lost handily to every single Rogue preamp on hand (Metis, 99 Magnum, Athena). Etched and tonally lean. The Sonic Frontiers entry-level line stage fared equally poorly. The modern ARC preamps (Ref 6) are wonderful, like from a completely different world - but expensive! The Rogue Athena clobbered everything in that old shootout, and are in your price range when they come up - but the ones with the stepped attenuator aren’t the smoothest ergonomic experience. Sometimes older VAC preamps come up in this range - probably a good option. Not sure I’m a huge fan of the modern Rogue RP-series preamps, but better than ancient ARC and BAT models. |
@hoytis I like ARC but the LS2b is from around 1994 and almost 30 years old. If you really want to go down this road I’d make sure that verifiable service records exist. Also get the s/n up front — ARC will be able to tell you what service was performed if they did the work. I recommend looking for a newer preamp if you can expand your budget. Good luck! |
Most Conrad Johnson preamps are good and will give you the warmth you are seeking. You might find a 17LS or an 17LS 2 in your price range. Do you keep your ML power amp switched on? That’s something to think about… if you’re leaving the power amp on, then switching off a tube amp might cause some unwanted thumps into your speakers. Some are worse at that than others.. |
Another vote for ARC. Listen to one first to be certain it has the basic sound profile that you are seeking. Next, consider how it will change/update the sound of your current system. Also, buy the best (most recent model?) you can you can afford... I recently purchased the ARC Ref6 SE, and I am continually impressed with it's Sound Q, and Build Q. The interface uses the typical buttons and dials, which is good enough for me. Good luck, |
