[Avro_Arrow]

Quote:

Originally Posted by pj_rage /img/forum/go_quote.gif Judge Buff and AA... are you guys talking about mods specific to the v1 or v2? It seems like the v1 based on the tubes you're talking about. Any idea how many of the same mods carry over to the v2?

In a word...Yes.

All the same mods will work on the 12AU7 version the same as the 6N11 (6922). It is exactly the same design. I would be interested in seeing some detailed pictures of the top and bottom to see how they handled the different heater voltage.

 

[pj_rage]

Well I have one on the way to play with, I'll be happy to post some pics if no one has by the time I receive it.

What should be my number 1, 2, 3 mods?

I have some Panasonic FC 1200uf and 1500uf 50V caps around... can I make use of them?

 

[Avro_Arrow]

Quote:

Originally Posted by pj_rage /img/forum/go_quote.gif Well I have one on the way to play with, I'll be happy to post some pics if no one has by the time I receive it. What should be my number 1, 2, 3 mods? I have some Panasonic FC 1200uf and 1500uf 50V caps around... can I make use of them?

It would be hard for me to rank them in order as they are all worthwhile...
The most important would have to be adding the Bias Capacitors, they are
missing from the original design.
The Power/Output Caps and MOSFET will all get you noticeable improvements.
Replacing the Bias Trim Pots is more to replace a poor quality component with
one more suitable. If you plan on doing much tube rolling, it is much easier and accurate to adjust.
Finally, if it still has the poor quality push button on/off switch, just remove it, jumper where it was and turn the whole thing on and off with a power bar.
If it has the newer toggle switch then it should be OK.

Here are some component suggestions, they are by no means the only ones that will work but are strongly suggested. I included Mouser Part Numbers.

Main Power Cap: one needed
10000uF @ 35 Volts. : 647-UFW1V103MRD
(this is very big and will just fit

Power Bypass Cap: one needed
1uF @ 63 volts : 505-MKS21.0/63/10
(replaces the cap directly behind the power jack)

Output Caps: two needed
1000uF @ 25 Volts : 647-UKW1E102MPD

Bias Cap: two needed
680uF @ 6.3 Volts : 647-PLE0J681MDO1
(soldered underneath across the Bias Trim Pot)

Bias Trim Pot: two needed
2K multi turn : 652-3266W-1-202LF

Output MOSFET : two needed
 IRF510 : 844-IRF510PBF

 Some suggested tubes for tube rolling were just covered in a previous post...

 

[pj_rage]

Quote:

Originally Posted by Avro_Arrow /img/forum/go_quote.gif It would be hard for me to rank them in order as they are all worthwhile... The most important would have to be adding the Bias Capacitors, they are missing from the original design. The Power/Output Caps and MOSFET will all get you noticeable improvements. Replacing the Bias Trim Pots is more to replace a poor quality component with one more suitable. If you plan on doing much tube rolling, it is much easier and accurate to adjust. Finally, if it still has the poor quality push button on/off switch, just remove it, jumper where it was and turn the whole thing on and off with a power bar. If it has the newer toggle switch then it should be OK. Here are some component suggestions, they are by no means the only ones that will work but are strongly suggested. I included Mouser Part Numbers. Main Power Cap: one needed 10000uF @ 35 Volts. : 647-UFW1V103MRD (this is very big and will just fit Power Bypass Cap: one needed 1uF @ 63 volts : 505-MKS21.0/63/10 (replaces the cap directly behind the power jack) Output Caps: two needed 1000uF @ 25 Volts : 647-UKW1E102MPD Bias Cap: two needed 680uF @ 6.3 Volts : 647-PLE0J681MDO1 (soldered underneath across the Bias Trim Pot) Bias Trim Pot: two needed 2K multi turn : 652-3266W-1-202LF Output MOSFET : two needed IRF510 : 844-IRF510SPBF Some suggested tubes for tube rolling were just covered in a previous post...

Wow super helpful post man, thanks a lot! I will definitely do some of these upgrades. Regarding tubes, I already have a few pretty good ones for my EF1 which uses the same tube, so I'll be able to play with those.

 

[lecky]

I got my Indeed G2 today, and tried a few tubes in it and compared it to my modestly modded Bravo (2nd iteration of the first design), swapping tubes between them and adjusting bias each time.

The first thing that is immediately apparent is that the Bravo is noisy by comparison - meaning background noise. The G2 is absolutely silent. In the G2 fine detail is more apparent, which could be an effect of the low noise floor, but doesn't seem to be. The modded Bravo also has a warm coloured sound compared to the G2. In all the G2 provides a very obvious upgrade from the Bravo - it absolutely justifies the extra cost - I can really recommend the G2 over the older model. I strongly suspect it's as easy a platform for mods as the original too.

As it's a somewhat different design, although along the same lines, perhaps I should start a new thread for it...

 

[schawo]

Did anyone try to use 2 Bravos for fully balanced operation mode with balanced DAC and balanced cans?

 

[pj_rage]

Quote:

Originally Posted by schawo /img/forum/go_quote.gif Did anyone try to use 2 Bravos for fully balanced operation mode with balanced DAC and balanced cans?

Is it possible to reconfigure them this way?

 

[Avro_Arrow]

Quote:

Originally Posted by schawo /img/forum/go_quote.gif Did anyone try to use 2 Bravos for fully balanced operation mode with balanced DAC and balanced cans?

I think the answer is no...

For balanced operation you need a differential amp.

 

[azncookiecutter]

Just got this amp, and from an initial listen, with the K701s, it matches better than the Little Dot MKV. Not bad for the $40 I paid for it.

 

[Judge Buff]

Quote:

Originally Posted by azncookiecutter /img/forum/go_quote.gif Just got this amp, and from an initial listen, with the K701s, it matches better than the Little Dot MKV. Not bad for the $40 I paid for it.

With a few $$ worth of capacitors, it will sound even better!

 

[Bassivus]

I've tried it with AKG701 and it sounded like crap to me... I have tried to like them, in several occasions during 2 months time. At first I thought I try upgrading them but latter I decided to sell them. It could not come close to my White Noise Head Amp

 

[azncookiecutter]

Well, there's still remains a bit of harshness in the upper end, but the bass is nicely filled out now, compared to the MKV. No other amp other than these 2 right now, but it'll hold me over till I get a new amp for them (MKV is a friend's, borrowing it for now).

 

[Bassivus]

In my opinion, Bravo amp did not have better bass but very overblown bass. Actually the hole sound was like someone cranked up the "loudness"... Drum cymbals glare overtake everything happening up there, mids gray and dull, and bass boomy, muddy and overblown. It reminded me of some late 70' mid priced tube radio's with loudness button.
Also there was considerable distortion after turning the volume more than 10 o clock...

 

[Avro_Arrow]

Quote:

Originally Posted by azncookiecutter /img/forum/go_quote.gif Well, there's still remains a bit of harshness in the upper end, but the bass is nicely filled out now, compared to the MKV. No other amp other than these 2 right now, but it'll hold me over till I get a new amp for them (MKV is a friend's, borrowing it for now).

If you do the mods Judge Buff and I have done you will be blown away by how good these little amps can sound...

 

[Judge Buff]

Quote:

Originally Posted by Avro_Arrow /img/forum/go_quote.gif If you do the mods Judge Buff and I have done you will be blown away by how good these little amps can sound...

A_A is right about doing the mods. I also cannot overemphasize what a difference there are in each individual tube I have. Since I did the tube biasing mod, the tube differences are even more dramatic. Whatever you do, break away from the stock tube... even the Electro Harmonix 6922.

The PS cap mod(s) will smooth and increase the tightness of the overall bass, but bass is controlled ultimately by the tube itself, so that aspect will be enhanced by the biasing caps.

I'm getting ready to change out my Silmic II 470s output caps to Muse (BiPolar) 1000s to see what a difference that will make. I'm also going to replace the biasing caps to alum/poly 1000s low esr caps.

Opening up the bottom of the board does add to the playing field a little... I may add another cap to the PS side (which, IIRC, will divide esr as it increases capacitance). I'm also replacing the switch and the headphone jack.

If you know which end of the soldering iron to hold, you can do the basic mods. With the "right" tube in the amp, properly biased, you may very well be blown away...