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Based on the comment heard from my last post here, I have bought the VK75SE while both VT100MK3 and VK75SE here in Hong Kong used market selling the exactly the same price.
I listened the VK75SE over few days, with also tubes rolling on its driving tubes,(not the 6c33c big tubes yet, waiting for the Russian original sealed boxed 6c33c coming next week)
I have found the mid range a bit grainy and not as rich when compared with my favorite Ayre V5xe. This result is opposite to my intended outcome, thinking the Triode VK75SE would be even more liquid and rich.
VK75SE bass profile clarity and weight is better than Ayre but Ayre seems to go deeper and a sense of more quantity in deep bass. My speaker is an easy driven type, JBL S2600.
(1) The little thin and grainy effect(major concern)and bass quantity issue, does it link with the wearing out 6c33c power tube causing a bit thin and grainy sound?
(2) Also the left channel produces a tiny (not seriously big) Deeeeeee electric noise, I swapped the tubes but the effect remains all left channel, Not surely if it relates to rectifiers issue or cap, Resistor issue. Anyone come across this thing?
Regards,
Eric
Follow Ups:
Having heard both ARC separates and integrateds, I must report that, the ARC separates are way better.
I need to re-clarify my findings on VK75SE
It is a great amp after replacing the leaky coupling cap
Stated in a new thread as many gloss over 6 month old threads.
I am happy that you have remedied your BAT amp and you are well satisfied with its performance.
Meat; It's the right thing to do. Romans 14:2
"" Also the left channel produces a tiny (not seriously big) Deeeeeee electric noise, I swapped the tubes but the effect remains all left channel, Not surely if it relates to rectifiers issue or cap, Resistor issue.""
I'd swap interconnects too from sources and between preamp and amp too when hunting noise. Even speaker wire physical proximity to noise sources can be an issue. Swap speaker wires at the amp and if the noise stays on the same side look at the speaker wire and its placement as a noise issue. Good luck.
ET
Their impedance does not go above ~4 Ohms, and seems to stay below 3 Ohms for the most of the power demanding range, not the mention around 2 Ohms from 80 to ~300 Hz. It is tough load for any tube amp (hey, it is tough for most SS amps), although BAT has settings for low impedance speakers, I wonder how much distortion you can expect. Victor could give input on that. Did you attach cables to LOW outputs?
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"One must be sane to think clearly, but one can think deeply and be quite insane."
Nice choice Eric-
which ever tubes you decide to use, give them several hundred hours of break-in prior to making any final judgement(s).
I am interested in BAT myself, keep me posted as you tube-roll and break-in this gear!
Disappointed to hear that the Ayre sounds better in the midrange. You might try clearing the tube sockets to get rid of the buzz noise. Sometimes the sockets get dirty or loose. Please let us know about your results with the new power tubes and trying different taps.
***waiting for the Russian original sealed boxed 6c33c coming next week
You should really only be using tested and matched tubes in that unit.
As far as the sound is concerned - did you try all three output taps? If not, please do so.
This amp is not a plug and play unit, if the tubes are in a sealed box that means to me that the tubes are not matched, they need to be in matched pairs, if not you are going to blow the fuse which is easy to replace or you may damage other parts that may need replacement. If you check the New Sensor site the best way to match tubes are to match them in the unit you are using. Here the closer they are matched the better your amp will sound, like a picture you are going to enlarge, the better focused the orignal the better the result. But tubes drift and fail just like ss devices, luckily you can rematch and aquire tubes a lot easier, and will sound just like new again as long as the parts in the unit and the unit itself is in spec.
From experience whenever I changed the 6V6 tube I needed to readjust the unit. I get the best performance using the reissue Tung Sol 6SN7, Gold Lion 6v6 tube, and the Electro Harmonix gold pin 6H30 tube.
The Nichicon LQ series used in this unit are obsolete according to the Nichicon website and passed its shelf life from other sources, changing them to Nichicon's newer, beefier, and higher temperature caps will give you another 10 years of unheralded sound. If your .22uf oil caps don't have the epoxy ends they need to be replaced, I suggest using Jensen's .22uf 1000v copper tube/foil cap.
If your pins are loose simply get a 90 degree plier and simply squeeze them tight going through the center hole of the socket, and as for the heat issue use the Noctua NF-A15 PWM fans.
We have seen several customer units where these parts shorted for no apparent reason, creating serious damage.
Victor;
I am/was considering buying a BAT VK 55se from a local gentleman, however, your comment gives me pause.
"We have seen several customer units where these parts shorted for no apparent reason, creating serious damage".
Are the problems stated showing up in all the BAT amps, or are they limited to a particular model? I just don't want to spend $2500 for a amp that may self destruct.
Thank you.
I was a vegetarian for 15 minutes, until the main course.......Meat; It's the right thing to do. Romans 14:2
We are not using them in our units, and the production parts do not have that failure mode.
The reason we changed out the original .22uf oil caps is because we all experienced an almost 100% failure rate, the caps were simply drying out probably due to the heat and poor seal design of the aluminum tube capacitor. I had asked the manufacturer of these caps as to which cap would he would recommend due to the heat and seal issue and he suggested using the copper tube variety which could tolerate the higher heat and had a better seal. I've also tried using their paper tube variety, but the best sound for me is the copper version, the only one I haven't tried is their ceramic tube version. These caps are the manufacture's higher end products and to date (going on 7 years) haven't seen a cap failure, but the best part, together with the better electrolytic caps, and other quality parts the amp is very stable and the sound is simple incredible.
Victor;
Thank you for the clarification.
I was a vegetarian for 15 minutes, until the main course.......Meat; It's the right thing to do. Romans 14:2
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