[amandarae]

Hello all,

I already e-mailed Jim to what I am trying to find out regarding the transformer temperature on my Cornet 2.  I taped a thermometer on the top of the transformer laminate(not the bell).  After turn on, say 20 minutes, the reading is 100 deg. F.  At about 35 minutes, its 110 and at about 1 1/2 hours and counting, it seems to settle at 115 deg. F.

Jim told me that that should be fine and be concerned only when it reach around 150 (I hope not!).  I like to ask if after an hour, the transformer on your Cornet(laminated top) feels hot also.  I can touch it but cannot leave my fingers for a minute.

I am about to pull the trigger for a new 300BX.  But $52 is $52 dollars plus shipping and I want to avoid it if it is not necessary.  For what its worth, my B+ is exactly 365.  The readings on the 330 and 300 V test point are spot on also.  Others are as follows:  155R(166), 155L(169), 150R(159), 150L(163), 150R2(160), 150 L2(163).  Actual reading is in parenthesis starting from the input 12AX7 going upwards.

Looking forward for your input.  I do not have any equipment except the Cornet that uses Hammond 270 or 300 transformers.

Thanks and regards,

Abe

[analog97]

Abe, I  have built both the Cornet2 and Clarinet with 370BX transformers.  After lots of hours, they are both warm to the touch.....not HOT.     I would listen to the advice of the design engineer, JH.....he knows best.

[dmcgown]

I believe this is normal behavior with Hammond transformers.  The resistance of the windings is fairly high, which results in a good amount of heat dissipation (IR losses) from the current flowing through the windings into the core.  The transformer materials (insulation) is designed for at least a 150 degree temperature, so if you can still touch it and keep your hand on it for a while, it is probably OK.  I don't think you will see much improvement with a replacement 370BX transformer, since the root cause is the winding resistance, which is a factor of the design of the transformer, not individual unit performance.

Now, part of the temperature rise may be thermal absorption from the rectifier tube in close proximity.  This will also cause the chassis around the rectifier to warm.  Again, I think the temperatures you are seeing are pretty normal with any tube gear I have built and used, so is really nothing to worry about.

[amandarae]

analog97, dmcgown,

Thank you sirs! 

 So far after 4 hours 45 minutes the temp is around 120 degrees.  I will let it run and enjoy the fruits of my labor.  Peace of mind is very difficult to find these days especially in audio 


 cheers

[Eric H]

I've been wondering about this for a while, too - but for exactly the opposite reason.  The 370BX's on both my Cornet2 and Clarinet take many hours to even get a bit warm and never get anywhere close to hot.  I run both of them with GZ34's and the operating voltages are within a volt or two of spec and they are quiet, sound great, etc.  I have numerous other tube units and for the most part their PT's get nice and hot...  I've never understood it.  It must have been that free superconducting coils upgrade that I got 

Eric

PS  amandarae - my Teres/Hagtech system is up and running now.  Doesn't look as nice as yours but sounds great...  I'll get a pic up one of these days...

[amandarae]

I've been wondering about this for a while, too - but for exactly the opposite reason.  The 370BX's on both my Cornet2 and Clarinet take many hours to even get a bit warm and never get anywhere close to hot.  I run both of them with GZ34's and the operating voltages are within a volt or two of spec and they are quiet, sound great, etc.  I have numerous other tube units and for the most part their PT's get nice and hot...  I've never understood it.  It must have been that free superconducting coils upgrade that I got 

Eric

PS  amandarae - my Teres/Hagtech system is up and running now.  Doesn't look as nice as yours but sounds great...  I'll get a pic up one of these days...

Hello Eric,

I guess its the luck of the 370BX draw!  Anyways, glad to hear that you got the Teres up and running.  I assure you, with the Hagerman phono stage, you will spend many nights wondering why you have to go to work the next day.  Assuming of course that you are not retired.  Seriously, I was in my brothers house this evening with the Cornet towed in hand (He got the 160, K&K phono, Bent NOH, and Orions speakers) and the evening was well spent.  The Cornet sings in there as if its life is at stake.  Wonderful is the word that comes to mind.  I got 6 hours on the Sonicap Platinums, Auricap, and Mundorf combo (resistors are stock with Rikens on the signal path) and if break in will still improve the sound of my unit, I think I have to owe Jim a dinner somehow.    The Cornet 2 in my opinion is, plain and simple, great.  But enough of that, not the right time and place to write a review

cheers