Indeed G2 tweaks and bias adjustment

[PinkFloyd]

Try some Panasonic FM caps (I can send you a few to try) IMO they sound a LOT better than the stock cap... what type of ELNA cap did you try? Starget, cerafine, silmic, RE2, RE2J? I have a hunch that Cerafine will sound nice in this position but would avoid starget, silmic, tonerex, RE2 etc.

Mike.

[sagitter]

Hi guys, somebody can help me?
I have buy this pre-amp.
I use it with an asus xonar u1 and with a notebook (toshiba satelite pro).
I use this combination:
notebook <--> xonar <--> indeed <--> headphone.
When I use the notebook with power supply (or power pack, sorry I'm not speak a good english... ) there's a noise.
This noise disappear when I remove the cable of power supply from notebook.
What can I do to resolve this problem?

Tnks.

[cadorne]

Dec 29, 2010 20:36:44 GMT PinkFloyd said:

Try some Panasonic FM caps (I can send you a few to try) IMO they sound a LOT better than the stock cap... what type of ELNA cap did you try? Starget, cerafine, silmic, RE2, RE2J? I have a hunch that Cerafine will sound nice in this position but would avoid starget, silmic, tonerex, RE2 etc.

Mike.

Sorry for the late reply. They were RE2J Elna Caps. I only heard that ELNA caps were GREAT when it comes to audio caps but didn't know there were a lot of varieties of ELNA caps (and other brands)!

I will try to look for Panasonic FM caps or ELNA Cerafine caps as you suggest.

Thank you very much for the offer but I would not want to be a bother.

[Deleted]

Jan 4, 2011 16:53:44 GMT sagitter said:

Hi guys, somebody can help me?
I have buy this pre-amp.
I use it with an asus xonar u1 and with a notebook (toshiba satelite pro).
I use this combination:
notebook <--> xonar <--> indeed <--> headphone.
When I use the notebook with power supply (or power pack, sorry I'm not speak a good english... ) there's a noise.
This noise disappear when I remove the cable of power supply from notebook.
What can I do to resolve this problem?

Tnks.

Seems like a grounding problem, or at least garbage from the power supply.
Can the power supply of the Toshiba be connected with a grounded mains lead ?
If so try it by connecting it's power supply to a grounded socket and see if this helps.

Can you describe the noise... hum... hiss..

[sagitter]

Jan 4, 2011 20:38:40 GMT @solderdude said:

Jan 4, 2011 16:53:44 GMT sagitter said:

Hi guys, somebody can help me?
I have buy this pre-amp.
I use it with an asus xonar u1 and with a notebook (toshiba satelite pro).
I use this combination:
notebook <--> xonar <--> indeed <--> headphone.
When I use the notebook with power supply (or power pack, sorry I'm not speak a good english... ) there's a noise.
This noise disappear when I remove the cable of power supply from notebook.
What can I do to resolve this problem?

Tnks.

Seems like a grounding problem, or at least garbage from the power supply.
Can the power supply of the Toshiba be connected with a grounded mains lead ?
If so try it by connecting it's power supply to a grounded socket and see if this helps.

Can you describe the noise... hum... hiss..

Hi!
Tnks for reply.
The noise is "hum" if I use the combination:
notebook <--> xonar <--> indeed <--> headphone
without the power supply in the notebook.
If I use the combination with power supply in the notebook the noise is "hem" (in italian, in english the "e" in the "hem" is equal to the "e" in the "bed", I hope that it is clear... ).
For notebook, I had used this without center pole (grounded pole) but the situation is not changed.
Maybe another problem is the cable jack 3,5 used to connect xonat to indeed, because if I move the jack in the indeed the noise change.
Not always, another strange thing is the lack of voice when move the jack in the indeed.
For some song I can listen only music but I don't listen the voice of singer...

There is some filter that can I use to resolve this problem?

[Deleted]

the lack of voice (and probably bass too) is most likely caused by the absence of a ground wire somewhere.
1 of the plugs probably has a broken ground connection or a socket that has a loose ground connection.
This might also explain the hum.

Check all wiring if the common (ground) wire is making a good connection.

Especially 3.5 mm wiring from Xonar to G2 and the sockets !

TIP: connect HP directly to the laptop and then add the G2 inbetween and finally add the Xonar to see where things go wrong.

[sagitter]

Jan 5, 2011 9:23:18 GMT @solderdude said:

the lack of voice (and probably bass too) is most likely caused by the absence of a ground wire somewhere.
1 of the plugs probably has a broken ground connection or a socket that has a loose ground connection.
This might also explain the hum.

Check all wiring if the common (ground) wire is making a good connection.

Especially 3.5 mm wiring from Xonar to G2 and the sockets !

TIP: connect HP directly to the laptop and then add the G2 inbetween and finally add the Xonar to see where things go wrong.

tnks for reply.
I have already test the combination:
notebook <--> xonar <--> hp
with or without power supply and there is not noise.
In this case, the cable jack 3,5 is not used.

I must test the combination:
notebook <--> indeed <--> hp

[PinkFloyd]

Jan 4, 2011 17:45:32 GMT cadorne said:

Dec 29, 2010 20:36:44 GMT PinkFloyd said:

Try some Panasonic FM caps (I can send you a few to try) IMO they sound a LOT better than the stock cap... what type of ELNA cap did you try? Starget, cerafine, silmic, RE2, RE2J? I have a hunch that Cerafine will sound nice in this position but would avoid starget, silmic, tonerex, RE2 etc.

Mike.

Sorry for the late reply. They were RE2J Elna Caps. I only heard that ELNA caps were GREAT when it comes to audio caps but didn't know there were a lot of varieties of ELNA caps (and other brands)!

I will try to look for Panasonic FM caps or ELNA Cerafine caps as you suggest.

Thank you very much for the offer but I would not want to be a bother.

RE2J are 105C versions of the 85C RE2 caps, they are pretty much general purpose caps. The ELNA "audio" caps are Cerafine, starget, tonerex and silmic.

[decru]

Hi, I'm new to this forum but I lurked it a lot during the latest 2 months !
First of all I want to thank you all, for the information and advices I found here. Then I would like to advice you that my English is far from good, so bear with it .

I approached this forum because I bought an Indeed G2 headphone amp one month ago: nice amp, very good value for the money. But, as any audiophile, I started immediately with tweaks buying a new valve, instead of the cheapo 12AU7 provided with the G2.
I bought an Electro Harmonix 6922 gold and I replaced it in the amp, adjusting the bias at 15.5V as advised in this thread and setting the selector to 6 valve type. Everything ok for an hour, then I decided to adjust again the bias as advised and, on one channel, I've noticed that the very cheap trimmer started to feel "strange" rotating it. Suddenly, the multimeter went out of range (it was on 20V DC ) and when I put it to 200V dc I found that the bias on that channel was 28V or so and there was no way to adjust it again.Connecting the HP I found that the left channel stopped working and simply started to do an hum noise (like the AC noise).
I suppose the trimmer is gone, and I would like to replace both with new one: is anyone of you able to advise a good quality one for replacement? The value is 2kOhm, 0.25 W I suppose, correct?
I hadn't the time to desolder the components and check them so I'm not sure the issue is only there. Any suggestion? Do you think the valve or other components have been damaged as well?
Thanks in advance to all of you!!!

Gianfranco

[Deleted]

No damage has been done to tube or other parts.
The pot simply went open circuit.

replace both pots for something with a similar footprint or with a different footprint with short wires.

Any pot with values of 2k or 2k5 or even 5k will work.

[decru]

Thanks Solderdude for the very quick reply!
I will try to replace it soon.
I would like to take this opportunity also to do some tweaks as suggested in this thread, also to make one on line order for components.
What do you advice? I'm considering cap replacement (105° instead of 85° type, 35 V instead of 25V), cathode bypass caps, IRL 510 instead of IRF510 provided. I would avoid changing heat sinks, if possible, at least the mosfet once, I can consider replacing the LM317 ones, but only without having to change tha amp design a lot or drilling the top plate.
Thanks, again!

[Deleted]

In this case I would:

replace the pots
replace output caps (25V and 105o) and power supply caps (35V and 105o)
add cathode caps.

changing IRF510 for IRL510 will do nothing sonically wise, IRL will give marginally higher maximum output power in this case.
Only recommended when IRF630 is originally fitted or if you need the extra 2dB output power/headroom.

[decru]

Hi again, I'm preparing the order on Distrelec. Some questions:

• about the bias trimmer: what's the power, are they 0.25 W or 0.5W?
  
• coupling caps: are low ESR type preferable? how much these caps affect SP? any advice on brands? On Distrelec I found some low ESR NIC components, unfortunately no Sanyo Os-con or Panasonic FM
  
• power cap: the larger the better or, also here, a low ESR would be preferable?
  
• bypass caps: do you advice these? what value: 3.3 uF 50V WIMA?
  

Thanks for you patience
G

[Deleted]

Mike answerred the cap questions above.

trimmer power is not of importance, there is a very low current.

Power cap the largest 35V type you can fit will do fine, in practice around 3300uF probably.

cathode caps: 470uF/10V or something around that value.

Bypass caps: matter of religion.
Technically, bypassing coupling caps has no measurable effects on the electrical signal (which I 'believe' is the only part that represents the audio).

BUT Of coarse the usual suspects will be better if you do mount them:
Bass tightens, highs get sweeter, more air around instruments, better placement, cleaner mids e.t.c. all aspects that have never been able to show any relation to the electrical signal.
So by all means... mount them.
They CAN't harm the sound anyway and it gives you the nice feeling you have done all you could and won't have to wonder IF it gets better if you didn't.
unless ... you have not fitted the one with the best properties...

Mind you it seems you get all of these improvements no matter what mod you perform (read all the raving review about ANY mod in ANY gear in EVERY forum and notice the same improvements occur.

Bypassing power supply caps is totally another matter.
In opamp circuits, digital circuits and fast amplifiers it is mandatory and verifiable and highly measurable too, but not always audible !

P.S. I know many will disagree (and I know I am wrong) and it's their full right to think so.
This is my opinion... so there is no need to engage in fruitless arguements in the G2 thread.

[wilsonkg]

Hello all, I am a noob to the forum and would like to say that I have enjoyed all the great posts on here.

Nice job with all the mods people. I just received my new G2 recently and have applied most of the mods listed and have made a few of my own including the Voltage test points on the sides. I have started rolling tubes and have been through a few. I was using an Amperex Bugle Boy 12AU7 but my favorite tube so far is the "Realistic Gold Clad 6CG7 seemed more natural with better bass and treble". I have made all of the new heat sinks myself (Starting with a CPU cooler of course) and have tried to keep all the mods inside of the original structure. I have also completed the new heater VREG Mod in the front on the V heatsink and all I can say is "WOW" this little amp is truely amazing now. The new heatsinks have lowered the device temps by about 30 degrees C. Here are some pics for anyone who is interested. I hope you like the edge lighting effect.

I love this little amp and hope that other newcomers will also.

I would also like to thank Solderdude for all of his work and for providing a great instructional PDF link.








Cheers

[tuberoller]

Hi all, just wanted to thank everyone here for sharing how to make the Indeed G2 sound better! I have one with IRF510 installed and the Solderdude cathode bypass cap mod (used 10V/100uF Oscons) took this little thing to the next level!
Apart from those caps, tube rolling (RCA 6201) and drilling four holes above the heatsinks I haven't done any other mods.
Which other mod would you recommend for someone with basic soldering skills, that would improve the sound?

Cheers

[Deleted]

Which other mod would you recommend for someone with basic soldering skills, that would improve the sound?

replacing the 2 output caps for 2200uF/25V Panasonic FM ? 105oC caps and replacing the 25V big cap for a 35V rated cap (probably between 2200 and 4700 whatever still fits mechanically.

The next real step up is feeding the heater from a separate supply (not recommended for beginners)

@ wilsonkg

That is some mighty fine cooling, way more effective then the standard cooling.

[PinkFloyd]

Jan 29, 2011 17:44:36 GMT tuberoller said:

Hi all, just wanted to thank everyone here for sharing how to make the Indeed G2 sound better! I have one with IRF510 installed and the Solderdude cathode bypass cap mod (used 10V/100uF Oscons) took this little thing to the next level!
Apart from those caps, tube rolling (RCA 6201) and drilling four holes above the heatsinks I haven't done any other mods.
Which other mod would you recommend for someone with basic soldering skills, that would improve the sound?

Cheers

Is that you Fred? (the original "tuberoller")

Mike.

[tuberoller]

Jan 29, 2011 18:41:26 GMT @solderdude said:

Which other mod would you recommend for someone with basic soldering skills, that would improve the sound?

replacing the 2 output caps for 2200uF/25V Panasonic FM ? 105oC caps and replacing the 25V big cap for a 35V rated cap (probably between 2200 and 4700 whatever still fits mechanically.

The next real step up is feeding the heater from a separate supply (not recommended for beginners)

@pinkfloyd No, it's a coincidence. I didn't realize someone already used that name. If you prefer I can change my nick, let me know.

@ Solderdude Thanks for your feedback!The big cap is a very tight 18mm squeeze, can't find caps exceeding 170K Coulomb charge that fit. What would be the benefit, beside lifespan and safety, to use 35V rated caps? Any thoughts on using two smaller caps in parallel (one below) in this spot?

[Deleted]

When you have the amp fed from a SMPS (that came with it) the power in the cap is replenished about 40000 x per second so when this is the case everything above 100uF will do.
Depends a bit on the feedbackloop in the power supply ...

2200uF/35 will do the job more then adequate.
If you want more capacitance for some reason (the bigger the better arguement ?) you can mount 2 in parallel, one on top and one directly below it, wiring as short as possibleotherwise the 'effect' will be less.

The main reason is lifespan and 'safety'.
It is never a good thing to apply a constant voltage of the same or marginally lower value then the rated one.
keeping a minimum 10% margin is highly recommended.
Also using 105oC caps near heat generating devices also prolongs life as these dry-out less fast at these temperatures.

[tuberoller]

Here's the end result (until I improve my solder skills).
Thanks again Solderdude, PinkFloyd and everyone else for the suggestions!

Attachments:

[Deleted]

looking good, sounding good.
The heater mod will bring the last bit of improvements (and in some cases a linear power supply).

Enjoy it, it's a funny rather pleasant sounding amp ones modded and adjust properly.

[tuberoller]

Just one more question about the heater mod: For those rolling mainly 12V tubes like myself, would there be any benefit in using a 1N4001 instead of SB140 diode to get rid of the excessive voltage on the heaters?

[Deleted]

The diode is there to lower the 6.5V coming from the TSR2465

6.5V is slight overvoltage and with regular tubes 6.3 is about max.
The SB140 has a forward voltage of about 0.3V @ 300 mA so brings the voltage down to 6.2V which is preferred over 6.5V (slight undervoltage is better then overvoltage as far as lifecycle is concerned)

The so called 12V tubes are specified for 12.6V but 12V tubes always have a centretap dividing the heater in 2 parts 6.3V/150mA heaters in series (that's where the 12V/150mA comes from)
In the G2 the 12V setting actually connects the heaters so they are in parallel making 6.3V@300mA making it the same as a 6V tube heatervoltage wise.

In this case the voltage needs to be dropped about 0.2V too, hence the SB140 (or similar Vf Schottky diode).

If a 1N400x were used the voltage drop over this diode would be about 0.55V and be too much.

The heaters would not be getting 6.3 but around 6.0V which is too low.

In case you make a linear regulator or an adjusted switchmode one you can leave the diode out and adjust the output of such a voltage regulator to 6.3V (or very close to it)

[Deleted]

After some questions about the separate heater mod explanation I found the pdf lacking some much needed details for performing this mod properly.

I now made a more elaborate version with much more info on what needs to be done and why... and how.

This is the new file:

www.mediafire.com/file/ccw7g2f8u97elpd/modifying%20the%20Indeed%20G2%20amplifier%28f%29.pdf