9V Tube Headphone Amp

[CynicalMan]

The tube pins 8 and 3 both connect to ground.

For the transformer, you're measuring resistance, not impedance. The impedance is like the resistance, but the impedance is used with AC signal, while the resistance only applies to DC signal. In inductors or transformers, the resistance will be much lower than the impedance. So, when you measure the resistance at 75 ohms, that probably means the impedance is 1k ohms. The 1.3 ohm resistance probably means an impedance of 8 ohms.

[PRR]

> I fear that I have messed up the valve by connecting wrong, they can ruin for having put another pin 9 volt?

No.

> The transformer impedance ... 75 ohm and 1 ohm resistance

Yes. Your ohm-meter reads DC, zero frequency. The transformer impedance is specified for AC, audio, above 100Hz frequency, and also with a load.

75 ohms and 1 ohm is about right for a "1K:8" transformer.

> one doubt the valve pins 8 and 3, do not connect to anywhere?

They connect to R2 and C3.

[JAROPDA]

hi can you help me identify the pin number 1 facing the valve from the bottom with its opening downwards?

thank you very much

[CynicalMan]

> one doubt the valve pins 8 and 3, do not connect to anywhere?

They connect to R2 and C3.

I think he's talking about the tube pin numbers, which are the other way around from the socket numbers. So tube pins 8 and 3 connect to ground.

hi can you help me identify the pin number 1 facing the valve from the bottom with its opening downwards?

thank you very much

Here's how the tube pin numbers line up with the layout:


So pin 1 connects to pin 6 and one side of the transformer primary

[JAROPDA]

hi this is well verified pre-punched board and component connections are correct?

thank you very much

[JAROPDA]

There are two things I did not add up, in the scheme resistor R4 is between pin 9 and   9+ volts
on the plate is between pin 9 and ground
pins 5 and 4 are connected to 9 volts on the plate and in the scheme will not see them
I think this'll make it to sound and solve these two questions.

thank you very much

a greeting

[JAROPDA]

Hello again, I logged in as pre-punched on the drawing board I've put in the previous post with the pin numbers of the valve socket, putting 9 volts on pins 4 and 5 and pin 9 to the resistance of 2ohmios and the other end of the resistance to ground.
Connected and works but I hear very very low volume ..... acting volume and tone butt but I hear sound but the guitar herself than go through my headphones Superlux HD681B 32-ohm impedance.
That if the sound is very compressed and hot
The amplifier starts ringing after about 10 seconds and the valve to spend some time playing is warm

What can be so low volume sound this little amp?

thank you very much for your support


greetings from spain

[JAROPDA]

Tested and verified if I work now ... but with very little signal.
I put 12 volts to the circuit and has risen considerably the volume of the circuit, and appreciate their dynamic sound and fat, now I see the filaments of the valve on and can not touch the valve, and is heated and burned.

My question now is, since it is an amplifier with a linear signal level without distortion or saturation, to remove the first stack of the transistor before its MPF102 and instead put your transistor circuit emulating a tube amp with J201 JFET 2N5457 transistors, etc.. as a prior while retaining the valve to provide the power amplifier to the circuit as the 12AX7. Is an emulator could build everything with valves with 2 or 3 12AX7 tubes -
12axu7?

By this I get to build an audio amplifier emulator valve-like system that uses the VOX brand with its "Valvetronix" a valve in the midst of digital circuits, in this case that would be serious and analog electronics.

I hope answers

thank you very much

[CynicalMan]

Sorry, I forgot to respond to your last post.

You should be able to see the filaments glowing in the tube even at 9V. What voltage are you getting over the 10 ohm resistor at 9V?

You can replace the MPF102 stage with a different circuit, but make sure that the output impedance isn't higher than 4.7k. If it isn't, just put the entire circuit before the MPF102 stage.

[JAROPDA]

The overall audio volume can not increase more on this amplifier?
I tested with 9 volts and sounds but with low volume and with 12 volts sounds more like twice the volume?
any idea?

It would be a good idea to insert a stompbox in this circuit amplifier emulating a known "Bass Boy` 59" circuit is a "fender Bassman 59" J201 JFET transistors.

How I can measure the output impedance of this circuit if it "bass boy `59 "?




WORKING TOGETHER?


The amplifier's overall sound is very good with body dynamics and gives good bass when you hit the sixth string of the guitar.

thank you very much
a greeting

[CynicalMan]

The output impedance of the Bass Boy is too high. In that case, I'd just remove the 22uF cap from the headphone amp, then just put the Bass Boy before it.

[JAROPDA]

There is possibility to make this valve amplifier Hi-Fi mode at the input to connect a mobile audio player, would you have to do 2 circuits?

thank you very much for your patience


a greeting

[CynicalMan]

Yes, but more importantly, you want a more hi-fi amplifier. This one is made to compress and to roll off treble. This is more what you want for that: http://diyaudioprojects.com/Solid/12AU7-IRF510-LM317-Headamp/

However, if you just want an mp3 player input to play along with, I'd just mix it in with the mono guitar input.

[JAROPDA]

I bought this amp valves with electro harmonix 6922.
They say it sounds great for Hi-Fi headphones.


http://www.ebay.es/itm/Indeed-G3-Headphone-Tube-Pre-Amplifier-6922EH-Class-A-/250880015472?pt=LH_DefaultDomain_0&hash=item3a699d3c70

and I will tell

regards

[craftyjam]

i know thisthread is almost 10 years old, but I'm gonna bring it up anyway.
After putting together the circuit I get a quiet and splattery output.
Has anyone else verified that it is correct? I've been banging my head against it on the breadboard for a few hours now.

[karsten_h]

hi out there... did you solve your problem getting that circuit going? the distorqueaudio.com website does not provide schematics any more for the projects & pedals is that stuff somewehere? would love to give that headphone amp a try but first want to build a valvecaster...