ECC88 OTL heaphone amp

merlin el mago · 06:38 PM

Looking for a tube headphone amp for my Sennheiser HD600 I saw this OTL with ECC88, it seem simple design & easy to make, advice & ideas will welcome.

PSU

OTL headphone amp

PCB

Picture

Also exist other version without integrated PSU.

Stixx · 22nd December 2011, 06:58 PM

Hi Merlin,

this schematic is loosely based on the better known Morgan Jones ECC88 OTL headphone amp which is an improved version of the famous Earmax amp.
Check out the info on
HeadWize - Project: The Morgan Jones Mini Tube Headphone Amplifier by Chu Moy since the original Headwize site is down.
I have built the Morgan Jones myself with LED bias for the first stage and a better psu (but now I would definitely use the Salas shunt for B+). When you are interested in a schematic I can mail it to you... it is easily built P2P on perf board. It is a nice sounding amplifier although there are better ones (non-OTL comes to mind).
When you are interested I can give the details for a very good sounding amp based on the C3G wired as triode, Salas shunt for HV and output transformers...

Cheers

merlin el mago · 22nd December 2011, 07:35 PM

Hello Stixx,

I'm looking for a tube headphone amp capable to drive my Sennheisser HD600 not necessary must be OTL, I'm interested on the C3G amp please send me details (I have Salas shunt HV for B+)

Greetings

Felipe

Stixx · 23rd December 2011, 10:04 AM

See schematic attached... it doesn't get much simpler than that.

http://s7.directupload.net/images/us...7/fg3o8znu.jpg

You have the choice of output transformers... I am using headphone opt's from Reinhoefer in Germany that sound very good at about 55€ a piece. But you can try anything that has about 7.5k:300 for your Sennheiser phones ( I am using Sennheiser's). Lundahl and Sowther have very good OPT's as well. Or have them custom wound at AE Europe in the Netherlands.

My amp is still on the breadboard
--> http://s3.directupload.net/images/us...8/rap477if.jpg
but will eventually look like this -->
http://s1.directupload.net/images/us...4/wzrdgt9j.jpg

Just my two cents in headphone amplifiers...but I have tried quite a few schematics and am currently building the eighth one

Stixx · 23rd December 2011, 10:18 AM

Forgot to mention that I am running the C3g at around 150V and 15mA now...but with the Salas shunt it is easy to try different voltages until you find your "sweetspot". The rectifiers provide a slow ramp up of the HV after about 20 sec.
Cheers!

merlin el mago · 23rd December 2011, 11:40 AM

Thanks for schematics & pics, where can buy the matched C3G tubes with a reasonable price with good quality?

Stixx · 23rd December 2011, 01:14 PM

check german Ebay...

here for instance
2 PIECES OF C3g-C3 g-SIEMENS-NOS-NEW-OWN BOX | eBay

Good seller, although prices have gone up over the last years. But a good ECC88 is not cheap either...

merlin el mago · 23rd December 2011, 01:19 PM

I have a couple of these E88CC Russian military stock bought to Erno Borbely (sounds amazing), could I use them?

Stixx · 23rd December 2011, 01:26 PM

No, ECC88 cannot be used in a single stage amp, it is best for preamp duty.

merlin el mago · 23rd December 2011, 01:38 PM

OK thank you.

22nd December 2011, 06:29 PM	#1
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Blanes - Costa Brava	ECC88 OTL heaphone amp Looking for a tube headphone amp for my Sennheiser HD600 I saw this OTL with ECC88, it seem simple design & easy to make, advice & ideas will welcome. PSU OTL headphone amp PCB Picture Also exist other version without integrated PSU. Last edited by merlin el mago; 22nd December 2011 at 06:38 PM.

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22nd December 2011, 06:58 PM	#2
Stixx diyAudio Member Join Date: Sep 2003 Location: Southern Germany	Hi Merlin, this schematic is loosely based on the better known Morgan Jones ECC88 OTL headphone amp which is an improved version of the famous Earmax amp. Check out the info on HeadWize - Project: The Morgan Jones Mini Tube Headphone Amplifier by Chu Moy since the original Headwize site is down. I have built the Morgan Jones myself with LED bias for the first stage and a better psu (but now I would definitely use the Salas shunt for B+). When you are interested in a schematic I can mail it to you... it is easily built P2P on perf board. It is a nice sounding amplifier although there are better ones (non-OTL comes to mind). When you are interested I can give the details for a very good sounding amp based on the C3G wired as triode, Salas shunt for HV and output transformers... Cheers

22nd December 2011, 07:35 PM	#3
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Blanes - Costa Brava	Hello Stixx, I'm looking for a tube headphone amp capable to drive my Sennheisser HD600 not necessary must be OTL, I'm interested on the C3G amp please send me details (I have Salas shunt HV for B+) Greetings Felipe

23rd December 2011, 10:04 AM	#4
Stixx diyAudio Member Join Date: Sep 2003 Location: Southern Germany	See schematic attached... it doesn't get much simpler than that. http://s7.directupload.net/images/us...7/fg3o8znu.jpg You have the choice of output transformers... I am using headphone opt's from Reinhoefer in Germany that sound very good at about 55€ a piece. But you can try anything that has about 7.5k:300 for your Sennheiser phones ( I am using Sennheiser's). Lundahl and Sowther have very good OPT's as well. Or have them custom wound at AE Europe in the Netherlands. My amp is still on the breadboard --> http://s3.directupload.net/images/us...8/rap477if.jpg but will eventually look like this --> http://s1.directupload.net/images/us...4/wzrdgt9j.jpg Just my two cents in headphone amplifiers...but I have tried quite a few schematics and am currently building the eighth one

23rd December 2011, 10:18 AM	#5
Stixx diyAudio Member Join Date: Sep 2003 Location: Southern Germany	Forgot to mention that I am running the C3g at around 150V and 15mA now...but with the Salas shunt it is easy to try different voltages until you find your "sweetspot". The rectifiers provide a slow ramp up of the HV after about 20 sec. Cheers!

23rd December 2011, 11:40 AM	#6
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Blanes - Costa Brava	Thanks for schematics & pics, where can buy the matched C3G tubes with a reasonable price with good quality?

23rd December 2011, 01:14 PM	#7
Stixx diyAudio Member Join Date: Sep 2003 Location: Southern Germany	check german Ebay... here for instance 2 PIECES OF C3g-C3 g-SIEMENS-NOS-NEW-OWN BOX \| eBay Good seller, although prices have gone up over the last years. But a good ECC88 is not cheap either...

23rd December 2011, 01:26 PM	#9
Stixx diyAudio Member Join Date: Sep 2003 Location: Southern Germany	No, ECC88 cannot be used in a single stage amp, it is best for preamp duty.

23rd December 2011, 01:38 PM	#10
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Blanes - Costa Brava	OK thank you.

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