Phase Splitter Name

Gold_xyz · 10th February 2008, 04:52 PM

Hi to all

Can I call this Splitter Catodyne?

A complete scheme can be seen here (use Acrobat 6.0 or more):
http://www.velleman.be/downloads/0/i...k4040_rev1.pdf

Tnx !

SY · 10th February 2008, 06:04 PM

It depends on the relative resistor values. If Ra1 >> Rk1 and Ra2 = Rk2, then it is a voltage amplifier coupled to a cathodyne (or concertina or split-load).

jane · 10th February 2008, 06:19 PM

This is one of the few split load inverters I have seen with grid leak bias.

Jan E

AndreasS · 10th February 2008, 06:30 PM

Probably this is a mistake of the schematic: R23 is to small for grid leak bias.

Regards Andreas

ray_moth · 11th February 2008, 08:44 AM

That is a very poor circuit, IMHO. There is no way a 12AX7 concertina splitter should be driving parallel PP EL34s in UL mode. Putting a 12AU7 common cathode amp stage on the front is a bad idea because of the tube's poor linearity and the splitter's bias circuit is wrong too.

AndreasS · 11th February 2008, 11:04 AM

The same concertina PI i found in the Telewatt VS 35 amplifier

http://www.audioantik.de/Stereo/VS55.pdf

Regards Andreas

richwalters · 11th February 2008, 03:09 PM

Ray ok (agreement to the worst of all specs)--I'm no fan of this kit stuff as I've had a couple to repair. ( and modded them to autobias)...

Interesting claim to spec, 0.1% thd at 1W o/p... that must surely be a mistake. Anyone else spot this ? Interestingly no thd figure is mentioned near full o/p.
Appro 3rd harmonic thd. Morgan Jones p.188 < mentions B9A ECC82 dual triodes are particulary gastly>. That's a published fact. so why use'm ?

The only way to get sensible performance with parallel pairs with low thd is either to use cathode follower drivers or an intermediate balanced push-pull voltage driver stage as per Williamson. I favour the latter as it cushions the split load.. I fail to understand why the authors of the kit haven't attempted this avenue.

Academically, readers can come to a swift sum-up by browsing Morgan Jones 3rd ed, classic amplifiers p. 412 onwards "the inherent driver defects of the Mullard 5-20". That's only with a conventional p-p pair not paralleled.
No hiding facts here.

richj

Gold_xyz · 17th February 2008, 10:27 PM

Quote:

Originally posted by jane
This is one of the few split load inverters I have seen with grid leak bias.

Jan E

Quote:

Originally posted by AndreasS
Probably this is a mistake of the schematic: R23 is to small for grid leak bias.

Regards Andreas

Hi

It seemed me that there was something strange.

In the scheme (k4040) I see a 0V grid polarization.
Also ECC82 as preamplifier and ECC83 as Splitter

This other scheme seems me correct, ECC81 with R12

http://www.velleman.be/downloads/0/manual_k8010.pdf

also

http://www.velleman.be/downloads/0/manual_k8011.pdf

Johan Potgieter · 18th February 2008, 12:00 AM

Oh boy...

The ECC83 split load as given will give a maximum peak signal output of about 40V before it runs out of steam (quickly hooked up) - and that is at quite visible 2nd harmonic distortion on the scope. (A 47K plate load in parallel with only 110K next grid resistors is looking for distortion.) Then grid-leak bias only works well when fed with a low impedance source. A feeding ECC83 is definitely not, apart from the grid leak resistor being too low - at least 10meg should have been there. Or it could have been direct coupled, although hardly successfull with an ECC83. I have said in the past that I do not see the ECC83 as a good choice for any kind of duty in a power amplifier. A pentode input to low mu triode phase-splitter would run circles round the above (ECF80, ECF82, 7199 etc. - and no comment from the "pentode-is-noisier" clan. That is in theory; certainly not audible in this kind of application.

I thought this kind of circuit has already been thrashed out to such an extent over 6 decades that should no longer appear compromised, . My apologies, but if this is the best Velleman can come up with, they have lost me.

Sorry Gold_XYZ, but that is not it.

AndreasS · 18th February 2008, 03:35 PM

The ECC83 (EF86, triode of the ECL86, ECLL80) are tubes, that can work with grid leak bias.
So this concertina phase inverter with grid leak bias we also meet in other amplifiers: Revox G36, Telewatt VS55, Grundig NF10.

The datasheet for the ECL86 (triode) gives an output voltage of 9 Volt RMS with THD 0,4%.

Regards Andreas

10th February 2008, 06:04 PM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	It depends on the relative resistor values. If Ra1 >> Rk1 and Ra2 = Rk2, then it is a voltage amplifier coupled to a cathodyne (or concertina or split-load). __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

10th February 2008, 06:19 PM	#3
jane diyAudio Member Join Date: Jul 2004 Location: Norway	This is one of the few split load inverters I have seen with grid leak bias. Jan E __________________ Life is hard - Then you die.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Is this a phase splitter?	tom-vdl	Solid State	9	15th October 2009 08:21 PM
phase splitter with Tr ?	sam8888ysl	Tubes / Valves	9	22nd October 2008 11:28 AM
HELP; DIY PP amp - it's phase splitter, or buy Chineese.	WE91	Tubes / Valves	19	30th October 2007 04:01 PM
6DJ8 as phase splitter.	kegger	Tubes / Valves	5	21st August 2006 03:03 PM
Phase splitter transformers	kopite	Tubes / Valves	2	15th July 2005 06:50 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read

10th February 2008, 06:30 PM	#4
AndreasS diyAudio Member Join Date: May 2005 Location: near Duesseldorf	Probably this is a mistake of the schematic: R23 is to small for grid leak bias. Regards Andreas

11th February 2008, 08:44 AM	#5
ray_moth diyAudio Moderator Emeritus Join Date: Jan 2004 Location: Jakarta	That is a very poor circuit, IMHO. There is no way a 12AX7 concertina splitter should be driving parallel PP EL34s in UL mode. Putting a 12AU7 common cathode amp stage on the front is a bad idea because of the tube's poor linearity and the splitter's bias circuit is wrong too.

11th February 2008, 11:04 AM	#6
AndreasS diyAudio Member Join Date: May 2005 Location: near Duesseldorf	The same concertina PI i found in the Telewatt VS 35 amplifier http://www.audioantik.de/Stereo/VS55.pdf Regards Andreas

11th February 2008, 03:09 PM	#7
richwalters diyAudio Member Join Date: Sep 2003 Location: Alps:Tube amp designs over 150W, SMPS guru.	Ray ok (agreement to the worst of all specs)--I'm no fan of this kit stuff as I've had a couple to repair. ( and modded them to autobias)... Interesting claim to spec, 0.1% thd at 1W o/p... that must surely be a mistake. Anyone else spot this ? Interestingly no thd figure is mentioned near full o/p. Appro 3rd harmonic thd. Morgan Jones p.188 < mentions B9A ECC82 dual triodes are particulary gastly>. That's a published fact. so why use'm ? The only way to get sensible performance with parallel pairs with low thd is either to use cathode follower drivers or an intermediate balanced push-pull voltage driver stage as per Williamson. I favour the latter as it cushions the split load.. I fail to understand why the authors of the kit haven't attempted this avenue. Academically, readers can come to a swift sum-up by browsing Morgan Jones 3rd ed, classic amplifiers p. 412 onwards "the inherent driver defects of the Mullard 5-20". That's only with a conventional p-p pair not paralleled. No hiding facts here. richj

18th February 2008, 12:00 AM	#9
Johan Potgieter diyAudio Member Join Date: May 2005 Location: Pretoria, South Africa	Oh boy... The ECC83 split load as given will give a maximum peak signal output of about 40V before it runs out of steam (quickly hooked up) - and that is at quite visible 2nd harmonic distortion on the scope. (A 47K plate load in parallel with only 110K next grid resistors is looking for distortion.) Then grid-leak bias only works well when fed with a low impedance source. A feeding ECC83 is definitely not, apart from the grid leak resistor being too low - at least 10meg should have been there. Or it could have been direct coupled, although hardly successfull with an ECC83. I have said in the past that I do not see the ECC83 as a good choice for any kind of duty in a power amplifier. A pentode input to low mu triode phase-splitter would run circles round the above (ECF80, ECF82, 7199 etc. - and no comment from the "pentode-is-noisier" clan. That is in theory; certainly not audible in this kind of application. I thought this kind of circuit has already been thrashed out to such an extent over 6 decades that should no longer appear compromised, . My apologies, but if this is the best Velleman can come up with, they have lost me. Sorry Gold_XYZ, but that is not it.

18th February 2008, 03:35 PM	#10
AndreasS diyAudio Member Join Date: May 2005 Location: near Duesseldorf	The ECC83 (EF86, triode of the ECL86, ECLL80) are tubes, that can work with grid leak bias. So this concertina phase inverter with grid leak bias we also meet in other amplifiers: Revox G36, Telewatt VS55, Grundig NF10. The datasheet for the ECL86 (triode) gives an output voltage of 9 Volt RMS with THD 0,4%. Regards Andreas

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)