[krankkall]

On the Indeed G2 and Bravo V1, the adjustments ARE a big deal!
I don't know about the Indeed, but on the Bravo, seems the QC is a bit.....lacking?
One channel was biased at 8.9v, while the other channel was biased at 15.9v.
I guess in the Bravo factory, their DVM.....er.....no workey?
Anyway, I biased both channels out at 15v, and the amp sounded MUCH better!!
 
Steve

 

[justhandguns]

Now that you fellows are mentioning about changing the resistors! I just wonder if changing all the resistors to better quality ones like Kiwame and Takman is worth to try?
Since we are all changing to better caps and tubes and why not upgrade the resistors as well? Anyone has tried a complete swap, if not, which particular resistors
are more critical to the SQ?
 
Quote:

................................... I had my Indeed G2 6922EH for 56$ (wining bid), it sounds pretty good, but I think I will mod it a bit, replacing the 25V power capacitors with 35V caps, trying to find the best output resistors (68 ohms seem to be the universal value), checking if the bias voltage has been adjusted precisely. I have to think about replacing heatsinks with bigger one because they're too hot, then I will try to find the tube that fit my ears.

 

[mhamel]

One thing worth mentioning with the mods - the PCBs in these amps aren't very good quality, so be careful when de-soldering, it's VERY easy to lift traces and end up with a lot more work on your hands.
 
That said, some basic mods can and do make a noticeable difference in SQ.
 
I also wouldn't be too quick to decide on a flavor of the amp based on the claimed brand components they use... considering it's a generic OEM that is building for everyone, and the track record of legit parts coming out of China, there's nothing to say that any of the caps or things like Dale resistors are what they say they are.
 
    -Mike
 

 

[Cya|\|]

Quote:

It seems the MOSFETs have a big influence on the sound, some people at Rock Grotto forum modified their amps because with original MOSFETs they had rolled of highs that make the amp sound warmer. The G2 has IRF510 MOSFETs, compared to other model, they expand the frequency range and lower the distortion. Output resistors also have some influence depending on which headphone (especially its impedance) you use.
 
I had my Indeed G2 6922EH for 56$ (wining bid), it sounds pretty good, but I think I will mod it a bit, replacing the 25V power capacitors with 35V caps, trying to find the best output resistors (68 ohms seem to be the universal value), checking if the bias voltage has been adjusted precisely. I have to think about replacing heatsinks with bigger one because they're too hot, then I will try to find the tube that fit my ears.

Please let me know what tube you'll choose ^^. I'm really looking forward to your tube matching with the lcd2.
But i'll stick to the stock tube choice. In the future maybe i'll buy a more expensive amp, i'm just a student right now. I'm paying the lcd-2 with summer work, but will end up with no money after that and the audio gd fun

 

 

[zest]

Quote:

Anyone has tried a complete swap, if not, which particular resistors are more critical to the SQ?
 

 

Indeed G2 and former version have some Vishay-Dale resistors and Alps potentiometer.
 

 

[zest]

 
Quote:

One thing worth mentioning with the mods - the PCBs in these amps aren't very good quality, so be careful when de-soldering, it's VERY easy to lift traces and end up with a lot more work on your hands.
 
 

If after modding you don't like the sound and want to go back

.
 

 

[zest]

Quote:

Please let me know what tube you'll choose ^^. I'm really looking forward to your tube matching with the lcd2.
But i'll stick to the stock tube choice. In the future maybe i'll buy a more expensive amp, i'm just a student right now. I'm paying the lcd-2 with summer work, but will end up with no money after that and the audio gd fun

 

I don't know for your lcd2 and I don't want to spend lots of money for my devices, Popcorn Hour A100 as Flac server > PCM 1793 DAC > Sennheiser HD 580 (next will be Fischer Audio FA003). I don't think expensive tubes such as Telefunken or Amperex Buggleboy would fit my budget setup, I'll try with some Genalex, Tungsram or Matsushita tubes.
 

 

[justhandguns]

Quote:

Indeed G2 and former version have some Vishay-Dale resistors and Alps potentiometer.
 

Yes, I realised that. But I have the Bravo V2, which has a shabby black PCB. I don't have much time this month, otherwise, I am planning to have a majob op with the little amp with some new caps and resistors. I have already got some components on the way :  2x Silmic II 1000uF two output caps, 2x Nichicon FW 4700uF caps for the power supply, 2x IRL530 MOSFET, Some Sylvania and Mullard 12AU7 tubes, a new toggle switch.
 
The ultimate goal is to swap all the crrappy components out and swtich to some relatively better parts. There are some options on my mind as well : Gold plated 1/4" socket, gold plated RCA socket, Takman carbon or metal film resistors etc etc.
 
On, by the way, I am a beginner in DIY electronics, I just wonder why some of you change the little bypass caps, the 1uF to WIMA type caps? What's the advantage? Please enlighten me!!

 

[zest]

My choice for output caps would be 2200µF to expand the low frequency limit, 105°C types because they're near heatsinks.
From what I read 1000µF is more than good enough for power caps but 35V, 25V is too close to 24V of the PSU.
It seems IRL Mosfets need less voltage than IRF, the LM317s will be hotter.
 
I'm not good in electronics, I suppose you mean the little caps in  parallel with output caps, I know what they're made for, but I don't see the advantage of Wima caps.

 

[justhandguns]

Quote:

My choice for output caps would be 2200µF to expand the low frequency limit, 105°C types because they're near heatsinks.
From what I read 1000µF is more than good enough for power caps but 35V, 25V is too close to 24V of the PSU.
It seems IRL Mosfets need less voltage than IRF, the LM317s will be hotter.
 
I'm not good in electronics, I suppose you mean the little caps in  parallel with output caps, I know what they're made for, but I don't see the advantage of Wima caps.

Thanks for the reply. By changing to the Silmic 1000uF 25V caps, I have already noticed a difference in more robust low end. I guess it's also the quality of the capacitors that counts.
I am now collecting the essential components, actually, I am planning to place the large caps underneath the PCB to avoid the heat from the LM317. I am also trying to source a slightly
taller heatsink for it, but I just don't want the heatsinks to protrude the surrounding parts to keep the amp relatively compact.

 

[jc22c]

Can it change another tube like 6DJ8 or 6922 maybe 12AX7 12AU7 in this circuit?
and change MOSFET can change sound?
Is anyone hear about Indeed or Bravo how it sound is?

 

[zest]

Quote:

Can it change another tube like 6DJ8 or 6922 maybe 12AX7 12AU7 in this circuit?
and change MOSFET can change sound?

There si a switch on Indeed G2 for changing from 6922/ECC88 (6V) to ECC81-82-83/12AT7-12AX-12AU7 (12V), but you need to increase the bias voltage with 12V tubes.
Some people did measurements with Mosfets, with IRF630 frequency response was limited to 10 KHz, with IRF530 20KHz, with IRL510 more than 30KHz.

 

[jc22c]

Quote:

There si a switch on Indeed G2 for changing from 6922/ECC88 (6V) to ECC81-82-83/12AT7-12AX-12AU7 (12V), but you need to increase the bias voltage with 12V tubes.
Some people did measurements with Mosfets, with IRF630 frequency response was limited to 10 KHz, with IRF530 20KHz, with IRL510 more than 30KHz.

There si a switch on Indeed G2 for changing from 6922/ECC88 (6V) to ECC81-82-83/12AT7-12AX-12AU7 (12V), but you need to increase the bias voltage with 12V tubes.
 
How does we to increase the bias ?
 
I means " Can you change sound in change IRF630 or IRF510 how about the different it is?"
 
 

 

[Judge Buff]

WIMA are very high quality caps. That's the advantage over the much cheaper stock film caps. I'd do the Silmics and the PS caps first. You may find that you won't need to do the MOSFET swap as the sound should really "open up" for you. If you do the MOSFET swap, you can use the opportunity to swap out some of the resistors. My Bravo V2 is "noisier" than my Indeeds are and I'm sure that the Dale resistors are a big reason for this. Increasing the PS caps sizes like you are doing will make the sound cleaner, too. It's all good... as long as your soldering/desoldering is decently done.
 
Even hooked to a scope, I doubt that you could see (or hear) the difference between takmans and panas or dales in these amps, but I'd use metal over carbon resistors in any headphone amp as the results are typically cleaner (less noise). This is just me... There are several threads on head-fi about this issue and people get vehement about their "side."
 
You'll reach a point of "diminishing returns" where the sound changes just aren't worth the effort you're putting into it.  The MOSFETS can be a pain... Tube rolling is easier and more fun IMO.
Quote:

Yes, I realised that. But I have the Bravo V2, which has a shabby black PCB. I don't have much time this month, otherwise, I am planning to have a majob op with the little amp with some new caps and resistors. I have already got some components on the way :  2x Silmic II 1000uF two output caps, 2x Nichicon FW 4700uF caps for the power supply, 2x IRL530 MOSFET, Some Sylvania and Mullard 12AU7 tubes, a new toggle switch.
 
The ultimate goal is to swap all the crrappy components out and swtich to some relatively better parts. There are some options on my mind as well : Gold plated 1/4" socket, gold plated RCA socket, Takman carbon or metal film resistors etc etc.
 
On, by the way, I am a beginner in DIY electronics, I just wonder why some of you change the little bypass caps, the 1uF to WIMA type caps? What's the advantage? Please enlighten me!!

 

[zest]

Quote:

How does we to increase the bias ? With trimpots on the PCB.
 
I means " Can you change sound in change IRF630 or IRF510 how about the different it is?"

 
With IRF510 you expand the frequency range to the highs.