Warning: getimagesize(http://www.audioroundtable.com/emoticons/smiley.gif><p>When) [function.getimagesize]: failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found in /home/audiorou/public_html/forum/theme/default/msg.php on line 134

Warning: getimagesize(http://img463.imageshack.us/img463/2004/e180f1eo.jpg) [function.getimagesize]: failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found in /home/audiorou/public_html/forum/theme/default/msg.php on line 134

Warning: getimagesize(http://www.audioroundtable.com/emoticons/smiley.gif><br>A) [function.getimagesize]: failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found in /home/audiorou/public_html/forum/theme/default/msg.php on line 134

Warning: getimagesize(http://img96.imageshack.us/img96/1002/e180f2rr.jpg) [function.getimagesize]: failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found in /home/audiorou/public_html/forum/theme/default/msg.php on line 134

Warning: getimagesize(http://www.audioroundtable.com/emoticons/smiley.gif><br>In) [function.getimagesize]: failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found in /home/audiorou/public_html/forum/theme/default/msg.php on line 134
AudioRoundTable.com: Group Build => 300B SE Project, Part 9 - E180F, E280F, D3a pentodes - triode connected

Home » Audio » Group Build » 300B SE Project, Part 9 - E180F, E280F, D3a pentodes - triode connected
300B SE Project, Part 9 - E180F, E280F, D3a pentodes - triode connected [message #31806] Thu, 09 March 2006 13:19 Go to next message
Damir  is currently offline Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)
These high-gm pentodes have the same base and similar specs. D3a and E280F are very similar looking – the same inside construction and height, «Siemens» produced, E180F is shorter. Those are SQ 10000h , gold pin tubes, and in this case it actually means something – OP is stable, they are close to the specs, the sound is beautiful.

When we connect screen grid g2 to the anode ("through" g2-"stopper" resistor R9 ) we get high-quality triode – high µ, high gm, low rp, very linear – Fig. 1 :


The same active load as before, similar OP. I measured A=µ about 50,5 with E180F, with E280F – 58, and D3a – 74.
E180F and D3a have about the same Ua=200V, E280F a little less, about 150V in this OP (11mA CCS, Rk=226 Ohms). All three tubes have rp in this OP about 3kOhms or a little bit more.
Input capacitance is the problem here – we have rel. large amplification, our Cag ~3pF, and Miller capacitance is large, especially in D3a case – about 220pF. We must use a lower value input pot than "standard" 100k, about 10k, 25k max. is still adequate.

Sound test: E180F has the softest and smoothest sound, E280F is drier, and D3a "in between", clean, a little dark top end, a little sharp, but not too much. But, all three have a good sound, IMO – in class "above" (say similar) 6C45Pi. E180F has great bass, detailed mids, punch, maybe highs aren`t too enhanced, but it is clean, balanced, smooth, dynamic, direct and natural – my overall favorite. It has the "right" amplification (A=50,5 times) – input sensitivity is 1Vrms for max. power. I tried a few more dB "in the red" (a little bit of "class A2"), and low output impedance of the driver and grid choke helped that distortion and compression almost aren`t noticeable.
D3a is also good, has the larger amplification (A=74), it means input sensitivity of about 1Vp=0,7Vrms for full output power – large "reserve" is possible.
E280F is also usable, but it`s a little rarer. One of the main criterions for the driver tube choice is "common", not expensive tube. Little E180F NOS "Philips" is all of that, and I`ll use it (with D3a as a backup, "plug in" compatibility) as a driver in my amp.
I tried resistive load too, just swapped CCS with 27k/5W resistor – circuit "pulls" about 10mA, and I measured A=66 times with D3a and A=45 times with E180F. Sound is a little softer and rounder, but very good, too.
Usual precautions about oscillations (stopper resistors close to the pins) are necessary. I used cathode bypass cap, it seems to me that the sound is somehow "fuller and smoother" with it.
Use high-quality, high-temp. electrolytic, soldered on the one cathode pin and the driver ground, short wires.

CONCLUSION: E180F triode connected driver "has it all" - from the "right" amplification (~50) to the "right" sound, it is quality NOS tube that isn`t hard to find or expensive. D3a is very close, and with a higher amplification factor.

Re: 300B SE Project, Part 9 - E180F, E280F, D3a pentodes - triode connected [message #31815 is a reply to message #31806 ] Fri, 10 March 2006 14:20 Go to previous messageGo to next message
Wayne Parham  is currently offline Wayne Parham
Messages: 16270
Registered: May 2009
Illuminati (33rd Degree)

Awesome, Damir. Just excellent. I wish I could listen to each of these circuits, maybe I'll be able to one day soon.


Re: 300B SE Project, Part 9 - E180F, E280F, D3a pentodes - triode connected [message #31817 is a reply to message #31815 ] Fri, 10 March 2006 15:06 Go to previous messageGo to next message
Damir  is currently offline Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)
Thank you. I tried so many things these days, and learned a lot. When you like it, it`s not too hard to solder and unsolder few wires and listen to the changes...again and again...
A few more experiments, then (finally) chassis build.

Correction! [message #31846 is a reply to message #31806 ] Mon, 27 March 2006 04:43 Go to previous messageGo to next message
Damir  is currently offline Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)

On the E180F driver schematic, the cathode resistor R6=226 ohms is noted like three (parallel) resistors of 680 Ohms on pins 1, 3, 8. This is not correct - E180F has only two cathode pins, 1 & 3. The pin 8 is actually g3 and shield.
I actually used three 680 Ohms resistors on the pins 1, 3 and 6 - where pins 3 & 6 are connected together. I used "blank" pin 6 like soldering terminal, and forget about it - it`s better to draw a schematics based on datasheets, and not on (bad) memories...
In fact, it is better and simpler just to use two cathode resistors of 453 ohms, connected on pins 1 & 3.
In Part 11 we`ll see the complete and correct amp schematic + wiring diagrams and tube bases.
Here`s the corrected E180F driver schematic.

Re: Correction! [message #32203 is a reply to message #31846 ] Fri, 29 August 2008 04:33 Go to previous message
matrix  is currently offline matrix
Messages: 2
Registered: May 2009
Esquire
Dear Damir (and everybody else).....

can anybody tell me if it will be possible for the E180F to drive 2 2A3 tubes in parallel....
i know that the capacitance of the output tubes is a bit of a problem - maybe better to use E280F but still i want to know if it will be possible to drive PSE with 2A3's using E180F........
any opinions
thanks in advance....


Previous Topic:questions re 300b group build
Next Topic:E180F, E280F driving 2A3 PSE
Goto Forum:
  


Current Time: Thu Oct 23 00:07:06 CDT 2014

Sponsoring Organizations

AudioKinesis
AudioKinesis
BOI Audioworks
BOI Audioworks
BuildAnAmp.com
BuildAnAmp.com
Crescendo Systems
Crescendo Systems
DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Smith & Larson Audio
Smith & Larson Audio

Lone Star Audiofest