Paul McGowan said We shipped a production amp to our distributor in Germany so it can break in before the upcoming show in Munich. I just got this note back from him.“the BKS is such a fantastic power amp. I cannot believe what I’m hearing. I’m so happy and say: congratulations !”
I suppose I’ll have to let him know how to spell it…
BKS is German for BHK 
I was trying real hard to be the first responder to this topic but for various reasons, it didn’t work. Being the BHK, I am receiving my amp, said to be #1, on Monday like some of you are. I thought I would describe what I am going to do when it arrives at the door to our house where most things do. I will unpack it and put it on a cart that I use that has a fold up vertical handle. I was originally going to bring it in the front door to place it next to my prototype unit. However, I had recently tested a similar kind of circuit sans tube input stage that I built for my self a number of years ago. I was curious as to what it would do into a 1 Ohm load with short bursts of a 1 kHz test signal. This is a valid way to do this as if one tried to do it in the steady state, it would blow the power supply rail fuses way before it came to clipping. Short result was that it put out in excess of 1.5 kW with one channel driven at the visual onset of clipping. So, I will take my new amp into my lab and test it the same way. I expect somewhat similar results. Then, I will take it in to listen to. Someone in another thread recently had mentioned something like would it take 400 hr to break in? NOT!! I believe it will come up to a close to it’s ultimate sound in perhaps 15-30 hr. I am very interested in what experiences you beta testers have regarding break in and various sonic impressions with your various kinds of speakers so please chime in on this thread!
Kind regards to you all.
Bascom King
My idea is to keep the BHK powered on (but without the signal and loudspeaker connections) on the floor next to my PassLabs x250 for 24-30 hours, then swap them (PassLabs onto the floor, BHK onto the rack) while the BHK is still warm and I still have a good memory of how the PassLabs amp sounds.
Alekz said My idea is to keep the BHK powered on (but without the signal and loudspeaker connections) on the floor next to my PassLabs x250 for 24-30 hours, then swap them (PassLabs onto the floor, BHK onto the rack) while the BHK is still warm and I still have a good memory of how the PassLabs amp sounds.Something that I didn't mention is that, surprisingly or not, break in is enhanced by playing music through the thing being broken in. For a power amp, it could be playing repeating CDs at what would be a normal loudness when driving speakers but substituting dummy loads of some 8 Ohm 10-25 Ohm per channel connected across the speaker terminals of the amp. One can do this at night for example using one's regular signal source.
BHK
This Saturday I went thru my rig and Kontak cleaned my PC’s, RCA’s, XlR’s, IEC’s etc., and vacuumed up the inevitable dust bunnies behind my rig. Re-leveled the TT. I can’t wait 'till tomorrow!
BHK said driving speakers but substituting dummy loads of some 8 Ohm 10-25 Ohm per channel connected across the speaker terminals of the amp.And the higher the resistance the less "powerful" the resistor can be. Good method, indeed! What wattage should I look for (approximately) for, say. 25Ohm? No less than 10W?
BHK Answers: 25 Ohm, 10W or Above would be OK.
Mine is on the truck for delivery. Has been delivered as early as 10:30am and as late as 7:30pm. Last delivery was at 4:30pm 2 weeks ago.
A short note with more to come. I got mine yesterday and am presently listening to it as I write this. Sounds pretty good from the get go 
Have any of you got yours going yet - or received them yet? Let the Beta Games begin!
I got my amp going about 0930 this morning and was amazed and delighted as to how good it sounded right out of the box. Later in the day, I am even more pleased! I don’t know about long break in because this one sounds real good right now. If it gets better, which it might, it will be a bonus. I hear the first mono is running and is going to be sent to me for checking out. I have attached a few pics of my setup with the new amp on the cart in front of my developmental prototype. Also a quick pic to the right of my source stuff.
One tester had a phenomenal experience with his and another person has problems with the right channel being weak and the amp going into protect mode. Sounds like a short on the output some how.
Received mine at 3:03pm today. It is 5:36 now.
I have not been able to listen yet as it keeps turning off and giving me a rapid blinking blue light.
I only get very soft music (should be normal volume at volume setting) from the right channel, when I turn it up it clicks off and blue light blinks.
I reconnected my D-150 amp and the system plays fine.
Any ideas?
Thanks,
Dave
BHK Here. Hi Dave. I am so sorry that you are having a bad experience. First, the RED LED was supposed to be on only when the unit is the operate state and not when the power is on in standby. Now about the amp turning off and weak sound on the Rch, check for a partial speaker wire short or the way it is connected to the speaker terminals. When I fired mine up this morning, I had a weak Rch and I did have a partial short on the speaker connections. Boy, this amp really sounded quite good and is really singing now! As a matter of interest, when I first brought the prototype amp that I did the development and debugging on into my system, I had a partial short on the Rch then. I couldn’t figure why the output stage current was spiking up so much when trying to set the bias!
in the tube box there is a red led shining when main power switch is on.
Dave
Dave said Received mine at 3:03pm today. It is 5:36 now.Dave, that sounds like a partial speaker short on that channel. Or some kind of connection of the speaker wires to the amp problem. Guess what, when I fired up mine the first time, the Rch was weak and I discovered a partial short from a cable going to my bass equalizer to ground. That fixed it and , wow, this one I have sounds sensational. BTW, when I first fired up the prototype amp that I developed the design on in my system, I had a similar short that REALLY heated up that channel's heat sink until I found the problem. Oh another thing to try is to disconnect the right channel speaker wires and see if it still turns off at a normal volume setting.I have not been able to listen yet as it keeps turning off and giving me a rapid blinking blue light.
I only get very soft music (should be normal volume at volume setting) from the right channel, when I turn it up it clicks off and blue light blinks.
I reconnected my D-150 amp and the system plays fine.
Any ideas?
Thanks,
Dave
Bascom
My amp is on order, but won’t be delivered for a few days, I was one of the last to order. In the mean time I have a question for BHK. I use Goertz MI-2 speaker cables which are a low inductance and low resistance design, the drawback is they have high capacitance. Per the Goertz website they are 5.7 nF per foot and I am using a 6 ft bi-wire pair. I calculate a total capacitance of 11.4 nF, correct me if I am wrong on that! The question is it has been reported that with solid state amps the high capacitance can cause high frequency oscillation leading to damage to the amp. I didn’t have that issue with my tube amp, but Goertz offered Zobel networks to prevent the problem. Problem is I did not get the Zobel networks. Will I have a problem with the BHK 250?
pmotz said Per the Goertz website they are 5.7 nF per foot and I am using a 6 ft bi-wire pair. I calculate a total capacitance of 11.4 nF . . .Bi-wiring cuts the resistance and the inductance in half in comparison to a single wire, but doubles the capacitance.
I believe at audio frequencies, capacitance is linear and thus the total capacitance is 68.4 nF.
But I am happy to be educated on the point if I am incorrect.
Thanks Bascom.
I checked for shorts and found none. Scott had me turn amp off and recycle. on second try the right channel was normal, but nothing from left. Switched inputs and still only sound from Right channel. I was supposed to look for 4 small red lights for fuses that may be out. Only red LED is in the tube cage. I asked scott if that was the fuse LED light?
Thanks again,
Dave
I asked this question in another thread, but got no answer. Were the amps tested by PSA before shipping?
Elk, I think you are correct, I made a mistake in my numbers, it’s 0.95 nF per foot, for a six foot length it is 5.7 nF total. Given biwiring it’s 11.4 nF total. Sorry for the confusion, I wrote my initial question and lost most of it and had to re-write it quickly since I was going out for dinner.
Makes perfect sense.
I’m interested in Bascom’s answer to your question as well.
Beta Tester Eric has yet to set up his handle for the forums and asked me to post his first reactions for him. He just installed a new set of IRS Betas and they still needed setup.
Paul,
As you've professed, so many things factor into that just right sound.
While I've been trying to place the speakers, the sound continued to be muffled. Things sounded like they were recorded with a wet rag over the mic. Piano and violin sounded flat and lifeless.
I hooked up the new amp and it was an OMG moment. Everything came alive. The clarity of the instruments was amazing. It was if I was having a live performance in my living room.
To give you a visual analogy, it was like going from a 2D to a 3D movie. The 2D transfers the flat image to your eyes, but the mind has to work to form the perspective; whereas, with 3D what you see is much closer to the original or live performance. Far less interpretation is required.
As further testament, my wife, who has very little interest in sitting and listening to music, joined me for the initial test run (in part, because I needed her help in lifting the amp into place). She had listen to a couple of songs on the old amp (not impressed, it didn't hold her attention). But, when we played the new amp she was amazed. The word she spoke was "Wow!!!!." This is like seeing the Grand Canyon for the first time kind of wow. We listened to ThePianoGuys "The Mission / How Great Thou Art" - off their Wonders album and it literally brought her to tears. Now if that isn't impactual, I don't know what is.
Dave said Thanks Bascom.I checked for shorts and found none. Scott had me turn amp off and recycle. on second try the right channel was normal, but nothing from left. Switched inputs and still only sound from Right channel. I was supposed to look for 4 small red lights for fuses that may be out. Only red LED is in the tube cage. I asked scott if that was the fuse LED light?
Thanks again,
Dave
Alekz said I asked this question in another thread, but got no answer. Were the amps tested by PSA before shipping?Tested, burned in, tested again.