Hi Pete,
I am really interested by this amp.
I plan to use it only for Headphone.
Currently AKG 702, so 64 Ohms.
- What is the best impedance for the output transformers? (in and out)
- Should also tune some other values?
I am really interested by this amp.
I plan to use it only for Headphone.
Currently AKG 702, so 64 Ohms.
- What is the best impedance for the output transformers? (in and out)
- Should also tune some other values?
For 64 ohm AKGs, I would stick with 8k:8 OPTs.
You can also experiment with changing the load resistors (R22 & R23) - with 64 ohm headphones you can use something a bit bigger that 10 ohms, maybe 22 ohms or higher, and get a little lower distortion.
Pete
You can also experiment with changing the load resistors (R22 & R23) - with 64 ohm headphones you can use something a bit bigger that 10 ohms, maybe 22 ohms or higher, and get a little lower distortion.
Pete
tube orientation
i am building a pcb version of the Jonokuchi. how do you determine the orientation to install the socket>
i am building a pcb version of the Jonokuchi. how do you determine the orientation to install the socket>
The sockets mount on the opposite side of all the components. The board is marked to show the location of the notch in the socket, which corresponds to the nub on the octal tube base.
I am really newbie with all tube related amp, sorry for my questions.
In the purpose to do an headphone amp only, does it make sense to get output transformer with lower power rating? 5W or even 2W? (In order to increase quality? bandwidth?)
It looks also that those tubes "13EM7" are not so easy to source, it is possible to use some alternative? Even if some values of the schematic must be changed.
In the purpose to do an headphone amp only, does it make sense to get output transformer with lower power rating? 5W or even 2W? (In order to increase quality? bandwidth?)
It looks also that those tubes "13EM7" are not so easy to source, it is possible to use some alternative? Even if some values of the schematic must be changed.
Touister said:
4.5 inches x 11 inches
Touister said:
Personally I used a 10W Edcor as shown in Pete Millett's design. I imagine a lower power xfmr would work adequately since it will be lightly loaded.
I got my 13EM7 from ebay, they range from $5 ea up to almost $20. I paid about $40 for a lot of 10 NOS tubes. I see you are in Germany, so maybe the shipping is cost prohibitive.
Thanks for your answers.
Yes all the sources I find for tubes are in USA, so each time shipping cost :s.
Yes all the sources I find for tubes are in USA, so each time shipping cost :s.
So I finally finished the Jonokuchi.
It is my first headphone amplifier, and I am very pleased 🙂.
I used output transformers from ESO.
It is my first headphone amplifier, and I am very pleased 🙂.
An externally hosted image should be here but it was not working when we last tested it.
I used output transformers from ESO.
And tubes?
What tubes you finally ended up with?
ESO - what is it?
The box looks nice. Diy or commercial?
What tubes you finally ended up with?
ESO - what is it?
The box looks nice. Diy or commercial?
Thanks
I used the recommended 13EM7.
ESO is Electra Sud-Ouest, in Europe it is much easier to order there, no import taxes and really fast. The quality is really good.
The box is based on a modushop case, and the front panel has been customize by them following my plans.
I used the recommended 13EM7.
ESO is Electra Sud-Ouest, in Europe it is much easier to order there, no import taxes and really fast. The quality is really good.
The box is based on a modushop case, and the front panel has been customize by them following my plans.
Optional Edcor Iron question was not answered ...
Back up in post #92
Some one asked the question about different Edcor OPT's and what would happen to the output power with different OPT's
I'm thinking of this amp to drive a set of Mini Karlsonators in a smallish room for listening to mostly blues. May add a sub woofer, but not sure.
So, I have a feeling a bit more output power may be need than the headphone version.
This amp seems a bit less intimating as a first tube build than the engineers amp.
Any comments?
Dave
Back up in post #92
Some one asked the question about different Edcor OPT's and what would happen to the output power with different OPT's
I'm thinking of this amp to drive a set of Mini Karlsonators in a smallish room for listening to mostly blues. May add a sub woofer, but not sure.
So, I have a feeling a bit more output power may be need than the headphone version.
This amp seems a bit less intimating as a first tube build than the engineers amp.
Any comments?
Dave
You can certainly increase power a little by changing to an OPT with 3.5k or 5k primary impedance, instead of the 8k I used. You could get maybe 4W out instead of 2.5W.
Edcor GXSE10-8-5k, or GXSE10-8-3.5k would be the parts.
The distortion will go up a bit. For blues this might sound a bit muddy if you go too far. So I would go with 5k.
Pete
Edcor GXSE10-8-5k, or GXSE10-8-3.5k would be the parts.
The distortion will go up a bit. For blues this might sound a bit muddy if you go too far. So I would go with 5k.
Pete
i am finally finishing my amp. all components are on and am ready to connect the transformers and power it up. once the power is applies, and assuming it doesn't smoke, what test points/measurements can i use to confirm it is operating properly?
You can check the voltages (to ground) at the plate and cathode of each tube stage with a DVM, and see that they are close to those printed on the schematic. +/-10-15% is fine.
Pete
Pete