[Puma Cat]

Originally Posted by Calculon

I received a used Conrad Johnson LP 125+ power amp (KT-120) about 8 weeks ago from Upscale Audio. The included tubes were new and required break-in which is one reason it took me this long to respond. Here are my impressions and how it compares to a CJ Classic 60 (EL34) which I have owned for 7 - 8 years.

CJ Classic 60 (EL34) with Vintage Tubes

Before I begin I need to point out that the Classic 60 is upgraded with vintage tubes, some NOS and some used. Compared to stock tubes the performance of the Classic 60 w/vintage tubes is significantly improved. I mean it’s not really that close. With vintage tubes the Classic 60 sounds more powerful than with stock tubes - greater musical authority and a stronger and more controlled bass. The specific tubes I’m using in the Classic 60 are 4 NOS Mullard EL34’s (from Brent Jesse), 2 used Sylvania 6DJ8, and a used RFT ECC82/12AU7. All used tubes had tested strong by experienced e-bay sellers. These sellers had a user rating of 100% or near 100%. The NOS Mullards are pricey, but they are the best EL34’s I have tried. I also like NOS Russian 6N3C/63PS as EL34 replacements, and they don’t break the bank. Other EL34’s I have tried are by RFT, Sylvania, and Groove Tube. They are good, but I definitely prefer the Mullards with the 6N3C/63PS coming in second. The control tubes can still enhance the performance of the Classic 60. Some people don’t give much love to the Sylvania 6DJ8 and RFT ECC82/12AU7 in general, but I find they sound excellent in the Classic 60 and definitely better than the stock tubes. Also, their cost on e-bay is fairly reasonable. Again, if you buy tubes on e-bay, only buy NOS or tubes that test strong – and only from experienced sellers with a 100% or near 100% rating.

LP125sa+ with a Mullard CV003 Tube

Now to the LP125sa+. This amp weighs 82 lb and with the shipping box, which contains plywood, the total weight was slightly more than 100 lb. For me it was a real chore to move around and unbox, but after some initial struggles I managed. The tubes came in a separate shipping box from Upscale Audio and as mentioned earlier were new and required break-in. After break-in I ended up replacing the supplied Phillips 6189 tube with a Mullard CV003 tube for use in the V1 socket. I have never cared for the Phillips tubes I have heard and the 6189 was no exception. On the other hand, the replacement Mullard CV003 is a great sounding tube, although expensive. The change to the CV003 tube in the V1 position of the LP125sa+ resulted in a noticeable improvement in sound. I bought mine on e-bay, but as of this writing there are CJ test grade CV003 tubes available for $90/ea at Upscale Audio.

Comparison

So how does the LP 125sa+ compare to the Classic 60 w/vintage tubes in my system (Tekton DI speakers, PrimaLuna Dialogue Premium pre-amp, Grado Statement 2 cart, Sota Sapphire w/Audiomods V tonearm, Manley Chinook phono pre-amp w/6N23P Silver Shield tubes)?

1) The Classic 60 w/vintage tubes has a powerful sound with musical authority and bass authority, but the LP125sa+ more so. The Classic 60 w/vintage tubes also has a somewhat darker sound character compared to the LP125sa+ which is not a good or bad thing for me.

2) The LP125sa+ also produces a larger sound stage, a greater sense of space or presence, and is slightly more forward than the Classic 60 w/vintage tubes. The slightly more forward sound is neither a good or bad thing for me. I once read an article by a speaker designer who said that good speakers and systems, in general, usually fall into two categories – “they are here” or “you are there”. Using the Classic 60, with or without vintage tubes, my Tekton DI speakers are definitely in the “you are there” category. However, when using the LP125a+ my system moves a bit toward the “they are here” category. Not a good or bad thing for me, but I thought it might be of interest.

3) The LP125sa+ has the edge in things like body, bloom, and decay although the Classic 60 w/vintage tubes is good in these respects as well.

4) The Classic 60 w/vintage tubes does have a bit more harmonic richness, and to my ear it is most noticeable in the lower treble and upper midrange. Imho, the Classic 60 w/vintage tubes produces slightly more beauty in the lower treble and upper midrange than the LP125sa+, but the LP125sa+ is no slouch here as well. On the other hand, the LP125sa+ has greater transparency throughout the frequency spectrum. Classic 60 w/vintage tubes sounds a tiny bit grungy/cloudy in comparison to the larger power amp. Please keep in mind that Classic 60 does not have the Teflon SE cap upgrade. This may or may not close the gap between the two amps.

Conclusions

Ok, so which power amp do I prefer - the Classic 60 (EL34) with all vintage tubes or the LP125sa+ with a single vintage Mullard CV4003 tube? For me (with the Tekton DI in my system) the more robust and more transparent LP125sa+ gets the nod over the more harmonically rich EL34 Classic 60 w/vintage tubes. I need to add that it is not a huge preference, but it is a definite preference. Also, please keep in mind that the EL34 Classic 60 does not have the Teflon SE cap upgrade. This might close the gap to some degree to some degree at least.

I want to add that I later hooked up a pair of modified 1.6 Magnepans. The Tekton DI are my preferred speakers, but the Maggies are pretty decent. Well this is going to be confusing, but the Magnepans seem to prefer the darker sound of the Classic 60 w/vintage tubes. There may be other factors (impedance, etc.?) but I did not look into it. At any rate the amps appear to be speaker dependent.

I hope this write-up is helpful and not too confusing. Bottom line is my first choice (of what I listened to) was the LP125sa+/Tekton DI speaker combination. It would be interesting to upgrade the EL34 Classic 60 to Teflon caps, but that probably won’t happen, at least for a while. It will go to my bedroom for the time being. I’m glad I have the LP125sa+, but I really like the CJ Classic 60 with upgraded tubes as well and could happily live with it - and that’s after hearing the more powerful LP125sa+. Additionally, at some point, I’ll probably look into a pair of very expensive Reflector 6H30P-DR tubes for the other 2 control tubes in the LP125sa+. As for now it sounds just fine the way it is!

Nice review and comparison. Is the output power tube for the LP-125sa+ a 6550?