Need Help please . Headphones into line up of tube amp .

[benoit26]

Hi im buying a custom made tube amp and the line out is made for 8 ohm

Can i plug headphones into that line out ??? the guy only plugged hes 8 ohm cabinet in it . But id like to plug heapdhones so i can play late at night in my bedoom .


i message the builder of the amp and it say that since a tube amp , the independence of the phones must be the same .

Now most stereo headphoens have 32 or higher ohm . 8 ohm headphones are impossible to find .


so i start checking and found some vintage 8 ohm headphones on ebay . would those work without blowing my tube amp transformer ????? these headphones are stereo 8 ohm , does it change something to mono or stereo 8 ohm or its the same 8 ohm .



i jsut want to make sure im not gonna blow out my tube amp cause i have the wrong indepency .

thank you very much for your answer . if you know something in guitar amp and voltage / ohm , please help me , im afraid to blow my amp .

[dsavitsk]

The only thing you are likely to damage is you ears. Get a high powered (12W at least) 10R resistor to put across the speaker terminals. Then hook up your phones in parallel.

But, if this is a high powered amp >15W , I wouldn't do it.

[benoit26]

oups my bad i forgot to say its a 2 watts hi gain tube amp ( which i can set the master very low and the preamp gain crank , so dont worry about my ears .


i wanna know about the amp .

[Eclair]

Originally posted by benoit26
oups my bad i forgot to say its a 2 watts hi gain tube amp ( which i can set the master very low and the preamp gain crank , so dont worry about my ears .

2 watts will still destroy your ears. Most modern dynamic headphones require at most 200 milliwatts (usually 100 milliwatts is enough for very loud listening).

[benoit26]

Originally posted by Eclair

2 watts will still destroy your ears. Most modern dynamic headphones require at most 200 milliwatts (usually 100 milliwatts is enough for very loud listening).

im not gonna crank it when ill play through my heapdhone , i have a master control , ill put it at 1 , i know this 2 watt is loud , but for late jamming . ill turn down the knob dont worry . i have a control for the preamp and one for the amp so ill put the master at 1 and the preamp gain at 10 .

dont worry for my ears .

im asking about the output transformer

its a 8 ohm line out , can i plug heapdhones into this ???? or it has to be 8 ohm heapdhone ??

thank you .

[benoit26]

here a text i found on building a cabinet :


Also BE SURE YOUR OUTPUT IMPEDANCE IS CORRECT! Many a would be speaker builder has miswired the speakers and ruined perfectly good amplifiers. Keep in mind that solid state amps and tube amps react very differently to mismatched speaker loads.

A solid state amp will still work with a higher impedance load that it is rated to drive. So if you wire your cabinet as an 8 ohm impedance and your amp is expecting 4 ohm, all that will happen is the output volume will suffer. Due to the fact that solid state have a very low output impedance, if you try to put a 2 ohm load on your amp from a miswired cabinet, it will try to source too much current and something will give (usually the fuse, but maybe your power BJT's?).

Tube amps are a different story. Efficiency is assured by the correct output impedance being reflected onto the primary of the output transformer, which in part determines the amount of current flowing through the output tubes. If you put on a wrong impedance (EITHER higher or lower), the output tubes "see" an impedance mismatch and actually put out LESS power into the cabinet. It can also cause transformer flyback and tube socket arching leading to a quick death to either the output tubes, cathode resistors, or the output transformer (maybe all!). In short, DON'T mismatch cabinet impedance with a tube amplifier!

[dsavitsk]

Originally posted by dsavitsk
Get a high powered (12W at least) 10R resistor to put across the speaker terminals. Then hook up your phones in parallel.

This is still correct.

Originally posted by benoit26
Tube amps are a different story. Efficiency is assured by the correct output impedance being reflected onto the primary of the output transformer, which in part determines the amount of current flowing through the output tubes. If you put on a wrong impedance (EITHER higher or lower), the output tubes "see" an impedance mismatch and actually put out LESS power into the cabinet. It can also cause transformer flyback and tube socket arching leading to a quick death to either the output tubes, cathode resistors, or the output transformer (maybe all!). In short, DON'T mismatch cabinet impedance with a tube amplifier!

And this is not.

[benoit26]

Originally posted by dsavitsk


This is still correct.




And this is not.

thank you really much

jsut one more thing to be sure .

http://cgi.ebay.com/Vintage-Stereo-M...QQcmdZViewItem

these one are rate at 8 ohm and has a mono/stereo switch .. would that be ok . does is still have 8 ohm in mono .


btw ** i cant put a 10 r resistor , im not a tech , i wont open the amp .

[kevinkr]

Originally posted by benoit26



thank you really much

jsut one more thing to be sure .

http://cgi.ebay.com/Vintage-Stereo-M...QQcmdZViewItem

these one are rate at 8 ohm and has a mono/stereo switch .. would that be ok . does is still have 8 ohm in mono .


btw ** i cant put a 10 r resistor , im not a tech , i wont open the amp .

Presumably then it also doesn't have a headphone socket. You should not plug a pair of headphones into the speaker output jack on this amplifier without doing exactly what Doug suggested at the bare minimum. Further you really should attenuate the signal before sending to your headphones - how much hum and noise can you tolerate? And what happens when you have the inevitable accident and put 2W into your headphones, blowing them up, and possibly destroying your hearing at the same time??

THIS IS A REALLY BAD IDEA!

I'd suggest you buy a power soak, and find a tech who can modify it for use with your headphones.

This from a former MI electronics designer.

[richwalters]

Originally posted by benoit26
oups my bad i forgot to say its a 2 watts hi gain tube amp ( which i can set the master very low and the preamp gain crank , so dont worry about my ears .

Exactly my point to come. In the 50's and 60's I worked in MI industry and studios and consequently suffered decades from Tinnitus. This was the cause. No cure.
The thing to watch out (as mentioned) is you must work with a power loss/attenuator. So much of todays audio equipment is so badly designed when it comes to switch on/off muting and the resulting dc thump will destroy your delicate earphone coils.

As part of the health and safety executive (HSE UK) All MI and audio company employers have to comply with mandatory limits to headphone levels by using headphones with in built limiters. Canford Audio stocks a wide range.

richj