I think he’s also referring to how much time it takes to warm up the Pass amp before he’s ready to enjoy it. It’s a regular topic. Not unique to Pass amps. My former dual mono class A/AB SS amp was the same way at 6-8 hours, it transformed into a gem once the transformers were good and saturated with heat at 6-8hrs. Parasound has made some progress with 1w standby pre-warming, and even then I demo’d one and still had to run it for a while before it sounded right to me. My mono tube amps I run now take a lot less time to be ready for listening.
@chungjh,
My local dealer sells Sound Lab and tube amps only. I’ve heard various SL model speakers there over the past 20+ years. In every case they were running two mono tube amps with the SL speakers. At 86db and 8ohms for your 545s, you’d likely need a (pair) of tube amps if you do decide to go to tube. More output tubes = more heat there too. Last time I was there, he was running a set like the larger 845s (huge) powered by two Quicksilver Mono 120 tube amps with dual KT150s in each, only 100wpc. One mono amp per speaker. While it sounded very nice, seems like many with your speakers run above 250wpc solid state amps regularly. If I had 545s and could not keep the 250.8, tube amps would be my choice. They do sound quite amazing with good tube amps. Maybe not as dynamic as your 250.8 Pass amp, unless you bought some with lots of tubes and back to heat again, IMO.
Pros/Cons:
While you only need one amp now to power your 545s with the Pass 250.8, you’d likely want/need a very large stereo tube amps or monos, and either case, still generating some heat but maybe less time for warmup.
Warmup:
The advantage I’ve found with my QS Mono 120s with two KT150 output tubes per amp, they have fewer tubes, don’t run hot, and never take more than 1hr to fully heat up, even at 45 min they start to sound pretty good.
Having heard a few different tube amps with your speakers, you’d need to choose wisely with tubes before you could effectively displace a Pass 250.8 amp I’d bet. Would mono tube amps be enough power and dynamics for you without buying some heat-monster tube amps, hard to say. Your speakers call for 50-600w. It really also depends on your room. At lower listening levels, sure might get away with 100w tube amps. Or, fans for the 250.8 and call it a day. Good luck.
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As @decooney indicated, the heat is not my biggest issue. It is the time to warm up. My logic is that tube amps will reach the optimum temperature more quickly than Pass Labs or other SS. Tell me if I am wrong. @chungjh You are correct when referring to some of the higher end amps with massive transformers. Most of my tube amps only take less than 1hr. I was a 35-year solid state amp guy, back to mono tube amps now days. Today, 45 minutes of warmup, ready to go. I simply don’t have the extra time or patience to fire up my former solid state amps and let them run for 6 hours of pre-warming for a 1-2 hour listening session. Was not worth it, IMO. Some of the more modern output tube amp designs and tubes do not get overly hot. I can hold my hand directly on the transformers of my current Quicksilver Mono 120 tube amps for ten minutes straight. Warm, but never hot. The output tubes are warm but not scorching like my older tube amps were at times. Similar to Carver’s amp designs. Ask the designer-mfg-seller to put a laser heat gun on it and tell you what the transformer/tube temps are after 6hrs. Try the same with the Pass 250.8 at 1hr, 2hr, 6hrs and see what you get and when it sounds good to your ears. If you go with tube amps, hang on to your Pass 250.8 if you can, its a lot of fun to rotate. |
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@chungjh
Sound labs are not bi ampable. Anyone have experience with high end D class amp?I know they are generally poo pooed, but who knows-may be there has been sufficient progress recently. Class D you say? How about Tube + Class D monos 600w @8ohms. Effective to drive your Sound Labs, with ease. Quick warmup, and ready for listening. https://www.psaudio.com/stellar-m1200-mono-amplifier/PS audio Mono 1200s. Ultra-linear, high-current, ICE Edge Class D technology for the output stage; and a discrete, Class-A vacuum tube for the all-important input stage. |
@chungjh
BTW, I need power in the amp because of the esl speakers.What do you all think? To: @chungjh I don't typically recommend dealers, in your situation it could be worthwhile to correspond. A local home audio dealer (Deetes) here in northern California USA has been in business since 1967, offers SoundLab speakers, sold Pass, more AudioNote and QuickSilver today. Primarily traditional TUBE amp systems only - that's his real passion, and specific electrostatic speakers. He's actually been selling SoundLab speakers as long as anyone around the world. I've known him for 42 years, seen and heard a lot of gear there new, used, trade-ins. A real treat to hear Soundlab there. Its a special place, last of its kind. The first time I saw and heard my own mono block tube amplifiers they were playing with massive SoundLab speakers there. Deetes is a big fan of your SL 545s too. Email and by appointment only. In business 53+ years. Deetes Sound Room Deetes Andersen deetessound@hotmail.com |
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@chungjh
I left my X250.8 on. This afternoon, it started sounding good around 2 hr mark. Less sibilance and harshness. Similar situation with my prior dual-mono MOSFET SS amps I ran for 20+ years. Mine did still keep sounding better at hour 4, and more dimensional at hour 8 when they are on all day long. Similar to Pass .5 and .8 amps. There are several threads on this, owners debating this. Tested and made notes today on my own tube mono amps with big transformers. 60 minutes was listenable, but hour 2 became plush and 3-dimensional. I cannot listen to them until at least 1hr warm-up. Kinda reconfirming again its just so much better at hour 2 with my tube amps too. Once it hits that bias set point, becomes very musical, enjoyable. |
Hi @chungjh`
"worth the price" is in the eyes and ears of the beholder and a person’s wallet I’d guess. CJ has a huge following just like Pass or Cary or Audio Note, etc. I’ve not heard the new Art150 or Art300 myself. I have been reading comparisons as I run two mono amps with KT150 tubes myself - wondering how and why the Art150 costs $15,000 more. Knowing CJ through colleagues, I’m sure it sounds``wonderful. I’d have to hear that amp in my own system on my speakers before I’d conclude its worth it.
A buddy owns that $20k GAT preamp by CJ. He compared it to my same $4.5k tube preamp with upgraded caps in it, and reported he’s selling the GAT preamp pocketing the difference. Don’t forget that Art150 amp will need a worthy preamp to go along with it. The cost adds up quick. I was at the same point you are now about "ears" and led myself back to tube amps, different interconnect cables, a tube DAC, and even changing coupling caps to smooth things out even more. There may be some things to try with your own 260.8 before going all tubes.
My own KT150 based amps were still a tad bright to me until I installed good NOS small input/signal tubes and changed coupling caps in them. Upgrading a standard build tube amplifier with standard upgrades used can be amazing when done by a good tech who knows how to improve a line. A good friend just had two different CJ" amps upgraded lately and likes the difference quite a bit. Everything I’ve heard myself at Deetes with SoundLab speakers has always been pleasant, yet it’s always been tube preamps and tube amps powering them. You could also try a proper tube preamp with your 260.8 in an effort to keep it. I’ve had email conversations myself with Nelson on this topic, he has many customers running tube based preamps with his XA and X amps. Feel free to send me a PM. |
@chungjh,
Thinking about your 260.8 amp. 55 degrees celsius measured at the heat sink is often referred to as optimum operating temp for many Pass amps. Reportedly, 55c is also a setup tuning point where Pass Labs sets the bias on many of their X/XA amps. It's re-checked many times during the first week of build validation testing. Bias is not set or checked until hot right at 55c. Some manuals note 55c as the sweet spot for warmup and listening time.
Last year I recall someone who finally sent their amp back in, found out it was not reaching optimum bias and temp. Simple adjustment fixed it.
Gotta infrared thermometer (heat gun) to check how fast it gets to 55c?
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