Is my ARC LS25 MkI holding back the sound?
 

I've read many posts in here recently about how ARC's REF pre-amps are so much better than the LS line. I really want to get an opinion of what is going on.

For a very long time, I had two VT100 Mk IIs bi-amping my Martin Logan SL3s (NOTE no external cross-over). The pre-amp is an ARC LS25 Mk I (4 - 6922 tubes).

I wanted to simplify my setup and upgrade. I read very positive reviews of the REF150 amp. So I recently purchased a used REF150 and I am still using my LS25 Mk I pre-amp. The sound improved a bit but not to the extent I was expecting.

So the question I have, is my LS25 Mk I pre-amp holding back what the REF150 can provide? If so, what would be the minimum ARC pre-amp I could use to make an significant difference in the sound?

I really like my LS25 because I can tweak the sound by changing the 6922 tubes but if it is limiting my musical experience, I probably should change it out.

Thanks,
Walter

Walter.......I think you already know the answer to your question.


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Very interesting. At one time I had a very similar system. ARC VT100 mk3, LS25 mk2 and Martin Logan SL3s. The Sl3s are very revealing. The better the electronics the better they sound.

I also spent a bit of time with a LS25 mk 1. I felt the LS25 mk2 was quite a bit better. The change to the 6H30 tube made a big difference. I now own a Ref 5se. It is a huge improvement over ALL previous ARC preamps. And I have owned quite a few in the last 30 years. I auditioned a demo LS27 for a few weekends. I did not think it was really worth the move from my LS25 mk2. I was sold my first evening with the Ref 5se. I woild suggest either a Ref 3 or Ref 5se. But not an original Ref 5 unless you can get it for around the same price as a Ref 3.

I also played around with using pair of VT100s to drive my SL3s. While I felt the sound was a little bit better, I did not think it was good enough to justify twice as many tubes.

I have not heard the LS25, but the difference between a VT100 amp and a REF150 should be considerable. The REF 150 is far more neutral without the 'silvery' cast of the VT100. Assuming the REF150 has reasonable fresh tubes in it, then something upstream is holding it back if you perceive little difference between the two amps.

ARC is definitely further along in the 21st Century. Their combination of the 6H30 with FETs in wholly new circuit designs are found throughout all Reference line-stages starting with the REF 5 and, I believe, the REF 110 amplifier. Some companies struggled with implementation of the 6H30 but ARC got it right. Your REF 150 will find an easy synergy with a line stage such as the REF 5 or 5SE.

Although not directly comparable model to model with yours, I had quite a similar experience. I was using the LS17 line stage with the VS115 (KT120) amp. I replaced the VS115 with the REF75, which by all accounts (reviews and comments all over the 'net) is completely superior.

In my system I gained a noticable improvement, but certainly more on the subtle side than the night-and-day difference I was expecting.

I then switched out the LS17 for the REF5SE. BOOM! There it was. I didn't experiment around to find out for sure, but I expect that what I finally heard were the improvements brought on by both the REF5SE AND the REF75.

Moral of the story: never let your pre-amp hold you back!

While you speakers are the voice of your system, the preamp is the heart. It has more of an effect on the sound than any other electronic component. And the Ref 5se is truly just amazing.

I have not used the LS25. However, I upgraded from a VS115 to a Reference 150, and from an LS27 to a Reference 5se, in that order. The amplifier upgrade was immediately noticeable. I could tell within the first ten seconds of listening that the sound had become more transparent and 3-dimensional. I would not necessarily call it a night and day difference, but it was very noticeable. Then I upgraded the preamp and heard a similar improvement, although not quite as big as with the amplifier change.

In general, the higher the quality of the system, the more noticeable upgrades to individual components become.

Thank you for all of the replies. I was afraid of the answers I was going to get. :)

Let me say that I did hear a difference between the 2 VT100s and the REF150 but it wasn't as large as expected. The bass was tighter and the treble was more extended (as extended as SL3s can be while being driven by a tube amp with a relatively high output impedance ;) ). All instruments and voices were clearer but again not a night and day difference.

The amp was advertised as having low hours - 750 hours but when I received it it had double that. I will be re-tubing it when it gets close to 2000 hours. I was thinking of getting ARC supplied tubes unless people here have other opinions.

So basically, I should be looking for a REF 3 or REF 5se to replace the LS25.

I wonder if the LS25 was also holding back the Pass Labs X350.5 that I tried before returning it and searching for a REF150. I did not like the sound of the Pass Labs at all. I found the bass just drowned out everything else. Of course, my panels were really old (20 years old). I just replaced them. Still I like the sound of an ARC tube amp more than the Pass Labs. I know that this is contrary to what many people seem to say when pairing Pass Labs amps with Martin Logans but that is my opinion.

You want a sufficient increment of improvement to make changing worth while and imo, you won't get that with a REF 3. The REF 5 or 5SE is a much better choice - it was made for use with the REF 150.

The LS27, that I recently upgraded from, is said to be close to the Reference 3, but I don't know how the LS25 would compare to it. I agree that you should go for the Reference 5se, if possible. It's supposed to be a big improvement over the Reference 5, and the Reference 5 was better than the Reference 3.