Welcome, Guest. Please Login or Register
Decware Audio Forums
05/15/21 at 00:10:36 


       


Pages: 1
Send Topic Print
SE84 clone headhone amp (Read 549 times)
funch
Senior Member
***




Posts: 91
SE84 clone headhone amp
03/01/21 at 22:50:24
 
My amp is a duplicate of an SE84 but using Transcendar headphone output trannies. I've learned a lot with this build, especially how different rectifier tubes have different voltage output, which may account for the differences in their sound.

I still have to install the anniversary mod's and try to remove a low-level hum, but it sounds fabulous.




Back to top
 
 
  IP Logged
piezoman
Seasoned Member
****


"If it ain't
broke, fix it!"

Posts: 585
Re: SE84 clone headhone amp
Reply #1 - 03/02/21 at 16:51:56
 
wow, that is fantastic!
Back to top
 
 

Taboo MK IV-25th, CSP3-25th Anniv. Ed., ZRock2-25th, ZBIT, Omega Jr. XRS ALNICO spkrs, Omega DeepHemp 8 sub,, Bryston BDA-3/BDP-2, Brick Wall 8, Ansuz Conditioning, IsoAcoustics spkr. stands, Audeze LCD-3F...PI Audio AQD1 Diffusers, DIY suite of room treatments.
  IP Logged
DPC
Seasoned Member
****




Posts: 229
Re: SE84 clone headhone amp
Reply #2 - 03/02/21 at 17:29:54
 
+1  :o
Back to top
 
 

CXN-CSP-ZROC-SE34-RL3
  IP Logged
Brian
Seasoned Member
****




Posts: 729
Re: SE84 clone headhone amp
Reply #3 - 04/01/21 at 03:27:57
 
A wonderful thing to build!
Have you any thoughts on the cause of the hum?

Brian
Back to top
 
 
  IP Logged
funch
Senior Member
***




Posts: 91
Re: SE84 clone headhone amp
Reply #4 - 04/02/21 at 23:23:12
 
Thanks. Yes I did solve it just a couple of days ago. The problem was the power supply. I installed a 15H/75 mA choke between the filter capacitors.  I also installed a 250 ohm/5W resistor in series with the choke to get the B+ power to the correct voltage. Both of these items replace the 1k ohm/5W resistor that is in the stock amp.

As designed, the power supply filtering in the stock SE84UFO is perfectly adequate for its intended use; speakers. It does hum, but you only hear it if you put your ear up close to the speakers. Not exactly a normal listening position, unless you're weird, or have a very small room. Wink
I had a Taboo II amp a few years ago which, I believe, was the first amp Decware put a headphone jack on, and it had a choke in the power supply.

With headphones though it is quite apparent/annoying. Installing the choke smooths out the waveform B+. Now, using the low impedance output (35-300 ohms), the amp is dead quiet. The high impedance output (300-600 ohms) has an almost imperceptible hum, which is masked if a gnat farts from across the room. I use Sennheiser HD800's btw (300 ohms), from the low imp jack.

With 2.3 watts output, I can only run the volume knob at or below 9 o'clock without going deaf. I can't wait to try a nice pair of planar headphones with it.

With the headphone specific output transformers, this amp is amazing. Very dynamic, but also smooth, with a great soundstage. Personally, I think this is the headphone amp Decware should build. But, that's my humble opinion. :-0

Back to top
 
 
  IP Logged
Brian
Seasoned Member
****




Posts: 729
Re: SE84 clone headhone amp
Reply #5 - 04/05/21 at 05:29:03
 
This is fantastic!  It is so much fun to get beautiful sound.  And to accomplish it with your own building adds to the enjoyment.  
I am happy for you.

Brian
Back to top
 
 
  IP Logged
funch
Senior Member
***




Posts: 91
Re: SE84 clone headhone amp
Reply #6 - 04/19/21 at 03:04:24
 
I have a question about plate voltage on the SV83 tube. Depending on the rectifier I'm using, I measure anywhere from 300 to 338 volts at the plate.
The SV83 datasheet (Svetlana) lists 300 as the maximum plate voltage.
Am I going to ruin my 83's by running over 300 volts?
Back to top
 
 
  IP Logged
funch
Senior Member
***




Posts: 91
Re: SE84 clone headhone amp
Reply #7 - 05/01/21 at 05:06:10
 
Final configuration. Probably.

Back to top
 
 
  IP Logged
Pages: 1
Send Topic Print