Hi Boys,
I'm seeing to make a ECL82 Headphone amplifier, using the pentode of ECL82 in a Cathode Fallower mode to buffer the courrent, and the triode making the amplification of the signal.
Can anybody know a good schematic in these condiction?
I'm thiking to use the Pentode to make a buffer of corrent to drive mine SENNHEISER HD580 who has a impedance of 300ohm.
Is this a good idea? The pentode of ECL82 is very similar of the EL84... Is this will be good?
Can anybodody comment it?
Best Regards,
Felipe Navarro
I'm seeing to make a ECL82 Headphone amplifier, using the pentode of ECL82 in a Cathode Fallower mode to buffer the courrent, and the triode making the amplification of the signal.
Can anybody know a good schematic in these condiction?
I'm thiking to use the Pentode to make a buffer of corrent to drive mine SENNHEISER HD580 who has a impedance of 300ohm.
Is this a good idea? The pentode of ECL82 is very similar of the EL84... Is this will be good?
Can anybodody comment it?
Best Regards,
Felipe Navarro
Hi Philipe
I remember to have seen something like this, but it definitely was for higher impedance headphones, more like 600 ohms.
I don´t think so, I am afraid. The pentode section of ECL82 in a CF will not be able to drive anything near 300 ohms, since even considerably stronger tubes like f.e EL86 in CF have a hard time to do so.
Not really. The closest to EL84 you can get with a pentode contained in a compound tube is ECL86, which is quite close to a power-derated EL84, indeed. I doubt as CF it will be able to drive 300 ohms headphones either.
Regards,
Tom
I remember to have seen something like this, but it definitely was for higher impedance headphones, more like 600 ohms.
I don´t think so, I am afraid. The pentode section of ECL82 in a CF will not be able to drive anything near 300 ohms, since even considerably stronger tubes like f.e EL86 in CF have a hard time to do so.
Not really. The closest to EL84 you can get with a pentode contained in a compound tube is ECL86, which is quite close to a power-derated EL84, indeed. I doubt as CF it will be able to drive 300 ohms headphones either.
Regards,
Tom
I have a headphone amp using the ECL82. It uses 12V mains toroidals as output transformers. I use parafeed to drive the transformer and has both loop negative feedback, and plate to plate feedback to smooth out the response.
The ECL82 pentode sounds a bit thin at 105V and 25mA, but with 40mA of current it fills out a lot. I have a pair of 8ohm headphones which sound great, and a pair of 32ohm SENNHEISER which sound a bit thin.
I can drag out the schematic if you are interested.
Shoog
The ECL82 pentode sounds a bit thin at 105V and 25mA, but with 40mA of current it fills out a lot. I have a pair of 8ohm headphones which sound great, and a pair of 32ohm SENNHEISER which sound a bit thin.
I can drag out the schematic if you are interested.
Shoog
Geek,
The circuit will be so so it here.
http://web.comhem.se/illuwatar//Tube/6AS7 Headphone/images/amp_schematics.gif
But with a pentode instead 6as7 to use a ECL82...
Like the circuit in here. But I don't know who I connect a pentode and who I design this circuit with a pentode.
Can anybody help me?
Best Regards,
Felipe
The circuit will be so so it here.
http://web.comhem.se/illuwatar//Tube/6AS7 Headphone/images/amp_schematics.gif
But with a pentode instead 6as7 to use a ECL82...
Like the circuit in here. But I don't know who I connect a pentode and who I design this circuit with a pentode.
Can anybody help me?
Best Regards,
Felipe
Attachments
I'd try inverted triode connecting the pentode of the ECL82 - see steve bench's site for more information on inverted triode operation.
Its not a new technique, but does enable a 'normal' tube to drive low required loads relatively easily.
However, as the grid takes the strain, the output power available is lower than the normal ratings - but should be plenty for the 30 or 40 mW you'll need, and he's used it to drive an 8R speaker..! so the load wont be an issue.
http://members.aol.com/sbench102/inverted.html
Just some thoughts
Owen
Its not a new technique, but does enable a 'normal' tube to drive low required loads relatively easily.
However, as the grid takes the strain, the output power available is lower than the normal ratings - but should be plenty for the 30 or 40 mW you'll need, and he's used it to drive an 8R speaker..! so the load wont be an issue.
http://members.aol.com/sbench102/inverted.html
Just some thoughts
Owen
Hi Felipe,
Sure, it's not that critical.
I've found the parafed arrangement is the least critical configuration for output transformers.
I custom wound mine. The second set of transformers I made, I used a pair of el-cheapo chokes from China and unwound them. They had exactly 1500 turns of wire on each. So I layed down one secondary winding, put the 1500 turns back on, layed a second secondary and paralleled the secondaries and have a fabulous little OPT for $2
Ok, a 6AS7 *can* do this. Low mu+low Rp is good for this. A little pentode unfortunately can not unless connected triode, making a super high Gm triode unit.
ECL82 won't cut it I'm afraid, at least not for 300 ohms, as mentioned elewhere. However, the 7KY6 trioded would probably do you fine for what you want. Rp is high, but it has Gm like no tomorrow!
mod_evil said:
Sure, it's not that critical.
I've found the parafed arrangement is the least critical configuration for output transformers.
I custom wound mine. The second set of transformers I made, I used a pair of el-cheapo chokes from China and unwound them. They had exactly 1500 turns of wire on each. So I layed down one secondary winding, put the 1500 turns back on, layed a second secondary and paralleled the secondaries and have a fabulous little OPT for $2
mod_evil said:
Ok, a 6AS7 *can* do this. Low mu+low Rp is good for this. A little pentode unfortunately can not unless connected triode, making a super high Gm triode unit.
ECL82 won't cut it I'm afraid, at least not for 300 ohms, as mentioned elewhere. However, the 7KY6 trioded would probably do you fine for what you want. Rp is high, but it has Gm like no tomorrow!
Geek,
I have some problems to make transformers... I live on Brazil, I haven't El-Cheapo transformers here, and the transformers in here is so critical to make/buy.
I have other choice... I can make a SRPP to make a gain, and a buffer with transistors to make the buffer to connect the Headphone to the tubes =D
What do you think about this idea?
Best Regards,
Felipe Navarro
I have some problems to make transformers... I live on Brazil, I haven't El-Cheapo transformers here, and the transformers in here is so critical to make/buy.
I have other choice... I can make a SRPP to make a gain, and a buffer with transistors to make the buffer to connect the Headphone to the tubes =D
What do you think about this idea?
Best Regards,
Felipe Navarro
Hi,
I'd say go for it. I like totem poles
Here's one I did based on a White CF actually:
http://geek.scorpiorising.ca/HeadphoneAmp.html
mod_evil said:
I'd say go for it. I like totem poles
Here's one I did based on a White CF actually:
http://geek.scorpiorising.ca/HeadphoneAmp.html
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