Ha, yeah... always expensive over there.
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Resurrecting this 4yr old thread about 845 based tube amps. I am considering commissioning a custom build for 845 SET monos. On the fence reading posts now on the pros & cons across a few different forums. @mesch did you ever try 845 based tube amps in your system? @jjss49 mentioned above trying and reselling Cary 805s not quite able to drive his Proacs how he wanted. This causes me pause as my 93db/6ohm speakers might be on the edge. I previously tried 10w triode and 50w parallel strapped pentode tube amps that worked fairly well, yet did not compare in response to my existing Quicksilver UL monos designed specifically running KT120s, KT150s. A local audio colleague told me true 50w triode monos with big iron transformers are different beast. Ive not tried 845 Triode monoblocks yet w/my speakers yet. Ask: Wondering if anyone here has been through true 845 triode monos and then went back to something like KT120 / KT150 monos instead. No SS amp replies please, already got that covered, hope to hear from 845 TUBE based amp aficionados. Thx |
I have corner horns so I can use just about anything. Saying that I just went from a 2 watt Decware to a 50 watt 845 OTL hybrid by Space Tech Labs amp and all I can say is wow. Al makes a higher watt version version but I didn't need it. I'm saving my money for his super rectifier that improves both depth and air. This amp is like a holographic generator with BASS! I was actually looking for a 300B amp but he played this amp first and there was no comparison |
@decooney I never did purchase the LM845. Stayed with separates. I purchased a Pass XA25 and shortly after an Aric Audio Transcend PP tube amplifier which I rotate in use with my Aric Audio 6SN7 based tube preamp. |
@decooney You are correct. In most rooms with speakers of that efficiency you’ll want more like 50 to 100 Watts. SETs, if zero feedback (and most are), have only about 20-25% usable power. Above that level, higher ordered harmonics show up on transients (where the music power is) and so causes the amp to sound ’dynamic’ since the ear uses higher ordered harmonics to tell how loud sounds are. This is why so many people comment about the 'dynamics' of SETs. Its really distortion masquerading as 'dynamics'. So if you are going to be successful with an SET, it really needs to be used on a speaker that is efficient enough that the amp never makes more power than that. The other problem SETs have is making bandwidth. Typically about 7-8 Watts is the most power you can get out of an SET design before the bandwidth becomes limited. Because most SETs are used on higher efficiency loudspeakers (like horns) they often will compromise the bass response to get the highs right. An additional problem limiting bass is an engineering problem; to operate correctly the power tube has to be placed in its most linear region of class A. There is something called a ’load line’ which helps the designer design the circuit that does that. The problem is most output transformers lack the inductance needed for them to make bass properly. This results in an elliptical load line at low frequencies- if you go low enough, its almost like the tube is driving a short, which can be very hard on it! So for best operation, the SET really should not be exposed to low bass frequencies. |
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