Understanding LP140M & LP125M &PR-140...

[slowGEEZR]

Once again, I'm coming to the pool of c-j aficionados for information in my knowledge quest on conrad-johnson gear. This time, I'm trying to understand the differences between the LP140M and the LP125M amplifiers. I'd also like to know if the PR-140 is much different, being a Premier product and not being a mono amp. So, here are my questions...

When comparing c-j's descriptions of the 140M and the 125M I noticed that they mentioned that the 140M uses Teflon coupling capacitors, but they didn't mention that for the 125M. I think that once c-j started using the Teflon caps, they continue to, so then the 125M should have them. Is that correct?

I also noticed that the output tubes are identical, but the input tubes (drivers?) are different. The 140M uses 3x6922, while the 125M uses 1x6922 and 1xM8080. The description of the circuit topology seem the same, but I'd like to know if the configuration for the 125M, being newer, is better for some reason. Also, is this why the power rating is different between the two?

Is the PR-140 considered a better amp because it has the "Premier" designation?

Thanks for your input on these questions!

[ronenash]

LP140M was a reference amplifier in which all top level components were used. This inclued teflon capactors and vishay resistors. It used a balanced on the input tubes which required tightly matched sections on the input tubes (6922). CJ latter did a revision to the circuit to make the section matching less critical but eventually droped the design in the ART amplifiers.

The LP125 is based on the reference ART circuit and is essentially a half size ART. When it first came out CJ were looking to create an amplifier for price sensative people and thus droped the quality of some parts vs. the LP140 and LP70 series. This was in the midst of the ecconomic crisis and CJ wanted to have an amplifier priced reasonably.

A year ago CJ started offering an SE version of the LP125m which ups the part quality to LP140 level including teflon caps and many vishay resistors. This is the version I use. Its a wonderful amplifier although more pricy. This is as close as you can get to their reference ART amplifiers at a reasonable price.

The Premier 140 is an older design and is a stereo amp vs the monoblock design of the LP140 and LP125. Its a great amp but the stereo design makes it very big and very heavy. Sound wise its not up to the level of the LP140 and LP125mSE. Still a great amp with a more classic CJ sound focused on the mids. You will lose some transparency, detail and frequency extension vs. the other two amps you mentioned.

Hope this helps.

[slowGEEZR]

Thanks ronenash, I didn't know c-j made an SE model of the 125M.

[Puma Cat]

Steve, I own the LP70S, and can attest to the fact that the LP (linear pentode) series are all wonderful amps...you couldn't go wrong with any of them. Personally, if I were to choose between the LP125 and LP140s, I'd opt for the 140s....very close if not essentially the same performance as the SEs but much better looking chassis! :). Thats just me, though.

[ronenash]

No dought the LP70 and LP140 are better looking :)

[slowGEEZR]

I figure I can't go wrong with any of them. I should probably just go for the LP275M and be done with it! As far as looks, I like both styles and there's something to be said for exposed tubes of the LP125 and the resultant tube glow.

[Myles B. Astor]

With the Wilsons I think you'd be happier with the 275 modded because of the additional power.

[ronenash]

The LP275 is a great amp but you need to consider the cost of replacing tube every 3-4 years. Retubing the LP275 would cost ~$1000. If you don't need that much power you are probably better off with the LP140 or LP125.

[Rafale]

from my german tube retailer

Tungsol KT120 34.20 euros
SED 6550 C 41,80 euros
EH 6550 25,20 euros
Tungsol 6550 27,50 euros
Sovtek 6550 WE 24,20 euros

[joeinid]

Hi Philippe :wave:

[Rafale]

Hi Philippe :wave:

Hello Joe....;) TAD ?

[joeinid]

Hello Joe....;) TAD ?

Hopefully Thursday !!!

[Coppy]

Steve,

I have the LP140s. My previous speakers were WP7s and now have Sashas. I believe the 140s have plenty of power to drive your speakers unless your listening room is very large. Most of us, with c-j's blessing, have replaced the stock 6550s with the new KT120 tubes. They seem to provide even more relaxed power headroom. There are a couple of good reasons to consider the 275s. One of course is power, and that is always a benefit especially at low frequencies. The second is a small increase in sound quality as the output transformer's bandwidth is just a bit better. If that is worth the additional maintenance, power usage, heat production from twice the driver tubes, weight and space requirements then go for it.

Have fun with the decision.

Bob

[Myles B. Astor]

The LP275 is a great amp but you need to consider the cost of replacing tube every 3-4 years. Retubing the LP275 would cost ~$1000. If you don't need that much power you are probably better off with the LP140 or LP125.

Think retubing is a bit more. The 275 has the same number of output tubes as my ART. Only difference is the small signal tubes. Retubing the ART costs $1600. But OTOH, the KT120s should cushion that hit a bit. Hopefully anyways :scratch2:

Also I haven't compared them but remember Roy Gregory having all three cj amps in house and as good as the 140 was, he felt the 275 was just in another class. There's a lot to be said for that sense of ease :)

[Rafale]

I agree :yes: I had the LP140M before the LP275M and there is a BIG difference

[slowGEEZR]

Thanks for all the feedback. I've got plenty to consider. For some strange reason, I am also drawn to a completely different amplifier and that is the Ampzilla! Dick Olsher's review of it was something else. I just know I love my tube sound from my Jolida much more than the transistor sound from my Krell, so I wonder why I'm even considering the Ampzilla and it's preamp! As Kelly Bundy used to say, "The mind wobbles.". :D

[slowGEEZR]

With the Wilsons I think you'd be happier with the 275 modded because of the additional power.

Myles, what mods do you mean, if I may ask?