Problems with G5 Amp

Message non lu par **charpy** » 20 sept. 2006, 17:12

well,

just try to add a coupling capacitor (22nF) between the cathode of the first triode and the tone stack. It may fix your bugg.

it is always advisable to 'protect' the tone stack with a coupling capacitor.

Frank · Message non lu par **Frank** » 20 sept. 2006, 18:26

charpy a écrit : well,

just try to add a coupling capacitor (22nF) between the cathode of the first triode and the tone stack. It may fix your bugg.

it is always advisable to 'protect' the tone stack with a coupling capacitor.

Hello Charpy!

I put in the Master Volume as it´s shown in the "quelques ameliorations possibles du projet G5" !

At the first build of my G5 it worked perfectly! There were no probs with that.
I think its a solder problem but i can´t find it. So i decide to build the amp again. Maybe this will help

Regards,
Frank

Message non lu par **charpy** » 21 sept. 2006, 17:35

have you made the version with "volume" after the tone stack plus "master volume" just before the power tube?
have you got the effect loop (a source of many problems...)

does the trebble or bass pot change something (like the volume pot does)?

silver-mica caps does not support to be overheated, if you have solder + unsolder it a couple of time it may have suffered.

eventualy the coupling capacitor before the master pot may leak, or the bloking distortion is too strong (so increase R18 att the EL34 grid) reduce the value of the master pot to 220k log in oder to drain more current from the EL34's grid to the ground (weird but possible because of the dispertion of tube caracteristics).

stard with easy change before you change the OT or tubes... but check the bias anytime

Frank · Message non lu par **Frank** » 24 sept. 2006, 15:24

charpy a écrit :have you made the version with "volume" after the tone stack plus "master volume" just before the power tube?
have you got the effect loop (a source of many problems...)

does the trebble or bass pot change something (like the volume pot does)?

silver-mica caps does not support to be overheated, if you have solder + unsolder it a couple of time it may have suffered.

eventualy the coupling capacitor before the master pot may leak, or the bloking distortion is too strong (so increase R18 att the EL34 grid) reduce the value of the master pot to 220k log in oder to drain more current from the EL34's grid to the ground (weird but possible because of the dispertion of tube caracteristics).

stard with easy change before you change the OT or tubes... but check the bias anytime

Hello Charpy!

Finally it works

I´ve ordered last week a couple of parts and build it up again...
Now it´s working perfectly!

I´m really happy now but i don´t know where the problem was

Thank you all for your help and support!

Regards,
Frank

EDIT ADMIN : Try to use the EDIT button please, Thanks !

Hello it´s me again...
I forgot ot tell you that it wasn´t the OT! I´m using the old one and it works great!

Bye,
Frank

Message non lu par **McColson** » 24 sept. 2006, 16:42

Cool ! stop, don't touch anything, close your chassis and pray for this amp working all his life

Frank · Message non lu par **Frank** » 25 sept. 2006, 16:45

McColson a écrit :Cool ! stop, don't touch anything, close your chassis and pray for this amp working all his life

Hi McColson...

NO! I´ve changed a few things... 8O
First i checked a few other powertubes... (6ca7,6L6GC,6V6)
Then i tried a rectifier tube (ez81) with the 6v6 and then with the 6L6
That looks quite cool 8) worked fine but sounded not so good

I missed the bass a bit...
Now it´s like it was at the begining...

Is it possible to switch between rectifier tube and diodes?
perhaps with an switch for the cathode resistor (r20) for other tubes too?

regards,
Frank

Message non lu par **McColson** » 25 sept. 2006, 21:32

Yes you can add a switch I have try on my G5, it's fun, but the voltage drop with the rectifier tube, change the HT and the bias.

here it's my schematic :
http://emmeffects.free.fr/MonG5/MCG5V1.gif

If you use a DPDT try to place a zener 20V on the PM, maybe need to place the fuse in other place (i don't know, i wrote rapidly), with the 1N4007 configuration to lower the HT in this mode so the difference with the rectifier will be lower.

For tasting many power tube, you have to solution, try SE fixed bias from the 50V bias tap, or try our system bias :
http://www.projetg5.com/modules.php?nam ... =0&thold=0

Frank · Message non lu par **Frank** » 26 sept. 2006, 9:27

McColson a écrit :Yes you can add a switch I have try on my G5, it's fun, but the voltage drop with the rectifier tube, change the HT and the bias.

here it's my schematic :
http://emmeffects.free.fr/MonG5/MCG5.gif

If you use a DPDT try to place a zener 20V on the PM, maybe need to place the fuse in other place (i don't know, i wrote rapidly), with the 1N4007 configuration to lower the HT in this mode so the difference with the rectifier will be lower.

For tasting many power tube, you have to solution, try SE fixed bias from the 50V bias tap, or try our system bias :
http://www.projetg5.com/modules.php?nam ... =0&thold=0

Hello McColson,
Call me stupid but can you explain me more what i´ve to do ?

What means PM and HT .... Sorry but i´m newbie with Tubeamps...

I´ve downloaded the "Schema G5 EZ80/81" and changed the amp shown in the schema!
It was only a test and the sound wasn´t so good. Is that the result of the other voltages?
About the bias... Yes i´ve thought about your version of the variable bias setting. I´ll give it a try today, if i´ll get the parts at my local dealer

Regards,
Frank

Message non lu par **McColson** » 26 sept. 2006, 13:21

Frank a écrit :
McColson a écrit :Yes you can add a switch I have try on my G5, it's fun, but the voltage drop with the rectifier tube, change the HT and the bias.

here it's my schematic :
http://emmeffects.free.fr/MonG5/MCG5.gif

If you use a DPDT try to place a zener 20V on the PM, maybe need to place the fuse in other place (i don't know, i wrote rapidly), with the 1N4007 configuration to lower the HT in this mode so the difference with the rectifier will be lower.

For tasting many power tube, you have to solution, try SE fixed bias from the 50V bias tap, or try our system bias :
http://www.projetg5.com/modules.php?nam ... =0&thold=0
Hello McColson,
Call me stupid but can you explain me more what i´ve to do ?
What means PM and HT .... Sorry but i´m newbie with Tubeamps...

I´ve downloaded the "Schema G5 EZ80/81" and changed the amp shown in the schema!
It was only a test and the sound wasn´t so good. Is that the result of the other voltages?
About the bias... Yes i´ve thought about your version of the variable bias setting. I´ll give it a try today, if i´ll get the parts at my local dealer

Regards,
Frank

PM means the center of the secondary on the power transformer (PT), and the HT means "Haute tension" in french, High Voltages in english.
The sound maybe sound not so good because the bias isn't not optimal when you use the EZ81. Try to use a system bias to re-bias correctly with the EZ81. And forget the trick with the zener for the moment.

Frank · Message non lu par **Frank** » 26 sept. 2006, 20:02

PM means the center of the secondary on the power transformer (PT), and the HT means "Haute tension" in french, High Voltages in english.
The sound maybe sound not so good because the bias isn't not optimal when you use the EZ81. Try to use a system bias to re-bias correctly with the EZ81. And forget the trick with the zener for the moment.

Hi McColson,

Today I build my variable bias system 8) It works great!
Thank you for explaining me the terms PT and HT but i think i do the tube rectifiering on the next amp. I´ve no space for another switch here

or i play only with 6V6 or 6L6 (i´ve only an EZ81 at the moment no EZ80)
But these two tubes sound to pale for me maybe your right and it´s the wrong bias... I´ll give it a try and report if it sounds good or not.

Thank you for the moment,
regards,
Frank

Message non lu par **McColson** » 26 sept. 2006, 20:10

My G5 with the EZ81 (the EZ80 has too voltage drop) and a 6V6JJ is one of my main configuration.
You can use our beautiful tool build by blacksnake : Electrosuite.
This tool is free and downloadable here in the section "Projets et Outils" in the under section "Outils" (Tools).
With the bias system, you will be able to load the 6V6 à 100%, and if it's sound not bassy call me

Frank · Message non lu par **Frank** » 26 sept. 2006, 21:24

McColson a écrit :My G5 with the EZ81 (the EZ80 has too voltage drop) and a 6V6JJ is one of my main configuration.
You can use our beautiful tool build by blacksnake : Electrosuite.
This tool is free and downloadable here in the section "Projets et Outils" in the under section "Outils" (Tools).
With the bias system, you will be able to load the 6V6 à 100%, and if it's sound not bassy call me

Hi !

Thats the same config i have!

well it sounds that your config is really bassy

okay i´ll give it a try 8)

Wow, i tried the Electrosuite... Well this is everything i was searching for

I don´t speak and understand France language but this will help me a lot! Thanks!!!

bye,
Frank

Message non lu par **McColson** » 26 sept. 2006, 21:47

You have my sample here :
http://mccolson.free.fr/sample/

Listen the Bossa 6v6 one and Aubert 6v6, I play a strat with single coils, so it's not specially bassy but you feel the 6v6 sound.

Frank · Message non lu par **Frank** » 26 sept. 2006, 21:57

McColson a écrit :You have my sample here :
http://mccolson.free.fr/sample/

Listen the Bossa 6v6 one and Aubert 6v6, I play a strat with single coils, so it's not specially bassy but you feel the 6v6 sound.

A oui ! Really bassy my speakers where jumping around

This sounds good okay, tomorrow i´ll try it again!

Thanks,
Frank

Frank · Message non lu par **Frank** » 27 sept. 2006, 11:51

Frank a écrit :
McColson a écrit :You have my sample here :
http://mccolson.free.fr/sample/

Listen the Bossa 6v6 one and Aubert 6v6, I play a strat with single coils, so it's not specially bassy but you feel the 6v6 sound.
A oui ! Really bassy my speakers where jumping around
This sounds good okay, tomorrow i´ll try it again!

Thanks,
Frank

Hello !

Today i´ve swapped to the 6V6 and the EZ81...
Now it sounds quite good. My "taux de bias" is about 76% and my bias current is about 45 mA. Is this okay ?
How about your settings? In the tube data sheets i only found 45-47 mA bias current so i think its okay.If i push it more does it sound more bassy and how long does my 6V6 life then ???

Regards,
Frank