I ordered a pair of Brimar CV4003 / 12AU7 and a pair of Mullard M8136 / 12AU7 Wrinkle Glass from Upscale today. I hope to report on these in a week or so!
I like the Cifte / 12au7 a little more than the Brimar CV4003 / 12AU7 - see what you think.
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Mark, these tubes have not shipped yet, so I could change my order. What did you like better with the Cifte?
more top end with the Cifte. Especially good with acoustic live recordings, really brings out the sparkle in my system, but not in a fatigue inducing way. the Brimar is my second favorite - the Cifte really shines with live recordings and I listen to a lot of live recordings.
I now got the pulsing again, now with the 12AU7 tubes. So I am going to use my RMA from PSA to repair this unit for me. I’ll be sad to see it go for a few weeks. But I know PSA will get this fixed up as it should be!
I have been hearing about the “pulsing noise” thing for a while now in the forum. The term seems to imply to me that there is a noise that pulsates - in intensity and at some rate? Does the music itself pulsate in amplitude? I would greatly appreciate some more accurate descriptions of how this sounds to those who have or have had this problem!
Thanks,
BHK
I believe I was the first to report it but that was probably a year ago so my recall is limited, but I’m pretty sure the music did not pulse. It was steady at about one cycle per sec, can’t recall if it changed with the volume control. I had it with several tube sets, I recall hearing it once in only one channel.
Yes I recall mine also taking awhile to start. As I’ve stated earlier they have an updated PIC that fixes it, they have been able to duplicate the pulsing I believe.
BHK saidI have been hearing about the “pulsing noise” thing for a while now in the forum. The term seems to imply to me that there is a noise that pulsates - in intensity and at some rate? Does the music itself pulsate in amplitude? I would greatly appreciate some more accurate descriptions of how this sounds to those who have or have had this problem!
Thanks,
BHK
Mr King, I hope this helps.
The music did not pulse. It is in the background on the music. At least with my unit it keeps happening on the right channel mainly. The volume and input had zero effect on what input on volume amount. The volume of the pulse did not increase. If you turn the music up, you will drown in out. Often times if I powered the unit down and re-powered it would stop ( sometimes ). Odd thing is it seemed to take a few minutes to start. Often within 10 minutes of power up. It would do this even if there wasn’t a source connected. I tried different amps, XLR, RCA, and power cables. Even another outlet. Still the same. I have an RMA so I will send the unit to PSA for repair. I HOPE it pulses for them, again it sometimes works fine for days, then acts up. I can’t pin it down.
Hi Bascom,
Thanks for inquiring about this intermittent problem some have had. Here’s my experience as follows:
My first unit had a noise problem, more like white noise with a little sparkle and pop in the right channel, audible from a few feet away.
Immediately I swapped the tubes but the noise did not follow the tube swap and remained in the right channel.
The noise did not change in amplitude when increasing or decreasing the volume control, except at the ‘0’ setting when it went away completely. I’m assuming there is a shunt at the output when the volume is at 0.
The headphone output was dead quiet, so I thought it might be caused from somewhere in the circuit after the amplification, maybe in the solid state buffering stage (it did sound like a noisy transistor, I’ve replaced a few in my Heathkit days!).
I sent the unit back to have it checked out but PSA was not able to reproduce the noise problem. Since the unit was new, I was offered a replacement which I accepted. I have had no issues with the replacement unit. Of course, Murphy’s Law states I will now 
David
Hi Bascom,
David’s description summed up my experience, though I could hear the snap/crackle/pop from my listening position (no music playing), at 10 feet from the speakers.
Thanks to exemplary PS Audio customer service, the issue was resolved. Not sure if they were able to replicate the issue.
What is still persistent even now is a moderate amount of hiss coming from my speakers (level stays same with/without music and irrespective of volume level). While I understand this can be traced to tube faults, this happens across a range of tubes (6DJ8 family and 12AU7s). Perhaps this is a system issue also? Gain issues? The only non-PS Audio gear in my chain are the Classe M600 monoblocks.
I would appreciate your take, and am very grateful you’ve chimed in and graciously offered some of your time to this issue. Thank you.
Paul, as you have read from a few posts I put up on the forum. I was having noise, pulsing issues with my BHK preamp. I swapped tubes, cables, and power outlets, even tried not using the P5 ( that was worst). I rearranged the rack and moved units around. I had been using a component unit fan to cool my amp ( not PSA sorry ). This unit uses a 12V wall transformer, which was powered from another P5 I own. I was chasing this noise from the preamp, which was very erratic since day 1. Well it has been 4 days without the noise. I assume the pulsing noise from the preamp had been caused by the fans or wall-wart? Odd since it never effected my solid stage preamp I have been using for years. I hope this stays noise free! Fingers crossed. Just to clarify, I am not using the cooling unit at this time. Or ever again I feel.
I hope this does it.
Electric motors produce back EMF and, of course, operate by spinning within a magnetic field, Noisy electrical beasts they are. It is easy to imagine that even a carefully built motor will disturb some components.
Out of curiosity, have you tried moving the motor around?
JM saidHi Bascom,
David’s description summed up my experience, though I could hear the snap/crackle/pop from my listening position (no music playing), at 10 feet from the speakers.
Thanks to exemplary PS Audio customer service, the issue was resolved. Not sure if they were able to replicate the issue.
What is still persistent even now is a moderate amount of hiss coming from my speakers (level stays same with/without music and irrespective of volume level). While I understand this can be traced to tube faults, this happens across a range of tubes (6DJ8 family and 12AU7s). Perhaps this is a system issue also? Gain issues? The only non-PS Audio gear in my chain are the Classe M600 monoblocks.
I would appreciate your take, and am very grateful you’ve chimed in and graciously offered some of your time to this issue. Thank you.
Regarding hiss - in the design of the BHK preamp, the main part of the volume control is in attenuation before the tubes and output stage. Therefore whatever hiss level that is coming out of the preamp is some function of the noise of the particular tubes being used. Now, how audible the hiss is is a function of the gain of the following power amp, the efficiency of the speakers, and the distance of the listener from the speakers. I have found that some of the 6922 genre of tubes are noisier than the supplied 12AU7 tubes. There really isn’t much one can do other than to have less gain in the power amp or less sensitive speakers. A properly designed attenuator between the preamp output and power amplifier input can help with this .
BHK
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Thanks for your reply, Bascom.
For what it’s worth, my amps have a 29 db voltage gain, and my speakers’ efficiency is 90 db. Not exactly sure how those numbers translate in regard to the hiss.
darrenv1070 saidUnit started to pulse this morning upon power up. I will ship unit back to PSA with RMA today. Odd today the repeated pulse is a lot faster today, sorta like a helicopter sound from a distance. I hope it acts up at PSA. ?Paul, as you have read from a few posts I put up on the forum. I was having noise, pulsing issues with my BHK preamp. I swapped tubes, cables, and power outlets, even tried not using the P5 ( that was worst). I rearranged the rack and moved units around. I had been using a component unit fan to cool my amp ( not PSA sorry ). This unit uses a 12V wall transformer, which was powered from another P5 I own. I was chasing this noise from the preamp, which was very erratic since day 1. Well it has been 4 days without the noise. I assume the pulsing noise from the preamp had been caused by the fans or wall-wart? Odd since it never effected my solid stage preamp I have been using for years. I hope this stays noise free! Fingers crossed. Just to clarify, I am not using the cooling unit at this time. Or ever again I feel.
Good luck. Mine has been running w/o issue since I got it back a week ago.
No problems w/ the stock Psvanes or Mullard, Brimar, Cifte 12AU7 tubes in my second wave beta BHK pre.
Once I started rolling 6/7v tubes I had problems. FYI voltage and bias jumpers were adjusted per tube following BHK’s post.
Tubes came from various vendors - Kevin at Upscale was very upfront w/ me and very accommodating. All the 6/7 v tubes I tried wound up pulsing into one channel. The sound was a “Woosh Woosh” @about one cycle per second on top of any tube hiss. Swapping tubes from one channel to the other might have the noise follow. In my preamp this noise generally occured on the right channel. This noise did not affect the music. No change when the volume was changed. I also noticed clicks/noise when changing volume w/ 6/7v tubes that I did not hear w/ 12v tubes. note, this noise is gone w/ new board.
When I had an Audio Research Ref 1 pre in my system I would experience occasional tube related noises.
The Ref 1 had a complement of 8 - 6922 series tubes and the top and bottom plates were heavily perforated for cooling.
The chassis was very sensitive, if I touched a Philips driver to a cover screw I would hear a “ting” through the speakers.
I was getting pulses and burps every now and then that I managed to track down and isolate to two causes.
One was my cell phone, the other was my antenna A/B switch which was directly beneath the pre.
Easy solution, turn off the cell phone and relocate the A/B switch.
Certain series of tubes can be more susceptible to RFI than others.
BHK saidI have been hearing about the “pulsing noise” thing for a while now in the forum. The term seems to imply to me that there is a noise that pulsates - in intensity and at some rate? Does the music itself pulsate in amplitude? I would greatly appreciate some more accurate descriptions of how this sounds to those who have or have had this problem!
Thanks,
BHK
Here’s the issue I’ve been experiencing: After about three months with the BHK, I started noticing a series of loud thumps in the right channel. They always happened starting about ten minutes after turn-on, and would continue irregularly for about an hour after that. Sometimes they were individual thumps, other times several thumps in rapid succession. The thumps were not related to the signal (i.e. not dependent on the music). Once they stop (after about an hour), they don’t start up again.
(Note that this is not the same as tube “woosh.” I use the pre with very sensitive speakers, and noticed a significant amount of white noise immediately after obtaining the preamp. I experimented with different 12AU7 tubes - the stock tubes and NOS Mullards - and finally settled on some Gold Lion reissues from Upscale Audio as the quietest.)
Having said that, because the “thumps” would go away in time, I suspected the tubes were still the issue. I replaced the Gold Lions with other identical tubes, and the issue briefly stopped, but then started up again the same way. Finally i moved the jumpers and put in a pair of Kevin Deal’s Tungsram PCC88’s.
It’s only been a day but the problem has not reoccurred.