[Eokboy]

Quote:

Originally Posted by rds /img/forum/go_quote.gif Eokboy Although I like the look of having all the cap spots filled I think you're going pretty far overboard on rail capacitance. Around 2000 uF would probably give you better results. Maybe someone else can weigh in on this. Looks great though. Also, what brand and model are the yellow output resistors?

I had some reservations at first, but after seeing other PPAs with as much if not more capacitance, I went ahead. I don't think the performance will decrease if you exceed. More like a ceiling maybe, and turn-on thump.

The film caps are Vishay Roederstein MKT1813, staggered values.

 

[rds]

So closer matching probably is worth the effort of swapping resistors?
I guess if I do it I'll put in sockets

 

[Eokboy]

Quote:

Originally Posted by rds /img/forum/go_quote.gif haha oh yeah... Still what are those output resistors? (the blue ones ). I used vishay 5% 1 W as I couldn't find any 1% 1W at 2.2 ohms.

Generic 1% 1W 4.7 ohms

 

[rds]

it seems like adjusting r12 negates the need to closely match the output resistors (assuming I measure the v drop across r34)

A larger resistor value might not cause any noticeable increase in distortion in high impedance headphones, but it may be more significant in low impedance headphones.

 

[rds]

Ah, I love this amp. All Muse KZ now.

I have some 2SA1358, 2SC3421 on the way from Beezar. Does anyone have experience with these vs the BD139/BD140 (what I'm currently using)?
I've heard that the ones I'm using are actually more detailed.

 

[PhaedrusX]

i have SC3422/ 2SA1359 in mine, but i have no basis for comparisons.
there is some useful information on output transistors here though:

discrete diamond buffer - parts list

 

[amb]

One thing to keep in mind about Steinchen's output transistor comments, is that they are based on the Millett Hybrid amp where there is no global negative feedback. The PPA is a feedback amp, thus those differences between devices as described are going to be much more subtle, perhaps not audible at all. Also, Steinchen's review is the opinion of one person, and everyone hears differently, and subjective descriptions of sonic attributes are always controversial, therefore they should be treated as such.

 

[JamesL]

Nice rds.

I was thinking about doing a nearly identical build.
Are those 16mm caps for the power supply section? I wasn't sure they'd fit in the case
I'm guessing the 470/330uF 50vdc ones would be ideal, right?

I'm curious.. I've seen those dip to dip adapters for the opamps, on more than one occasion, and never understood what they were for.. am I right to assume that the purpose is to make opamp rolling easier?

 

[rds]

Quote:

I'm guessing the 470/330uF 50vdc ones would be ideal, right?

Those are the 330 uF 50V Nichicon KZ. I don't think 470uF will fit that case. The ones I used can fit, but it's not too easy to do. You have to be meticulous with placing the c2 (blue film caps in front of them) and you have to mount the C1s slightly off center from the holes. You also need to use the holes that are spaced 7.5 mm. So it's a little tricky, but as you can see it can be done.
The c4 caps are also a tight fit but not as tricky as the c1s. I used 100 uF 25V Muse KZs for c4.
If you want to make things easier you could use Muse FG (for example) which are smaller and come in a 35V variety. The 470 uF 35V FGs will fit the regular cap spots which will make things easy.

Quote:

I'm curious.. I've seen those dip to dip adapters for the opamps, on more than one occasion, and never understood what they were for.. am I right to assume that the purpose is to make opamp rolling easier?

Yeah, pretty much. They're DIP8 sockets. I think everyone uses them when mounting DIP8 opamps. They're less than a dollar a piece.

 

[SLmutmut]

Hi all,

I haved builded my own PPA2 yesterday. But it's not good as i think

...
I used:
Elna Silmic2 for power
OPA134 for L/R
OPA627 for G
Buffer is same to schematic of tangentsoft:
all resister is same to schematic of tangentsoft:
http://tangentsoft.net/audio/ppa/amp...schematic8.pdf
Not bass boost.


I haved heared Mini3 amp, it's bass soo good, my PPA2's bass is light and not deep as Mini3. PPA's trebe is also high too ...


I don't know much about electric

How can i adjust R9 and R12, what is it real value ?
How can my bias output go to 30mA ... it's not warm any (i think it is about 30 C). Can I calculate it?
What should i adjust resisters ?!

Thanks for reading!
SLmutmut.

 

[FallenAngel]

Quote:

Originally Posted by SLmutmut /img/forum/go_quote.gif Hi all, I haved builded my own PPA2 yesterday. But it's not good as i think ... I used: Elna Silmic2 for power OPA134 for L/R OPA627 for G Buffer is same to schematic of tangentsoft: all resister is same to schematic of tangentsoft: http://tangentsoft.net/audio/ppa/amp...schematic8.pdf Not bass boost. I haved heared Mini3 amp, it's bass soo good, my PPA2's bass is light and not deep as Mini3. PPA's trebe is also high too ... I don't know much about electric How can i adjust R9 and R12, what is it real value ? How can my bias output go to 30mA ... it's not warm any (i think it is about 30 C). Can I calculate it? What should i adjust resisters ?! Thanks for reading! SLmutmut.

First thing is you might want to change the OPA134 to something nicer.

As per Tangent's instructions on his site:
1) R9 is for the biasing opamps into Class-A: read DC Volts across R10; for each 1V, you have 1mA of bias.

2) R12 is for the biasing buffers into Class-A: read DC Volts across R24; for 2R2, set it to 55mV (that's 25mA of bias).

The PPAv2 is not a bass-heavy amp but the clarity is nice. If you're getting bass worse than a Mini^3 with harsh highs, something is wrong.

What's is the current draw on the amp?

 

[MisterX]

Quote:

If you're getting bass worse than a Mini^3 with harsh highs, something is wrong.

OPA134's combined with BD139/BD140 output transistors would result in an amp that is brighter and have less bass then a Mini3.
How do you figure there is something wrong?

 

[SLmutmut]

Thanks FallenAngel and MisterX,

May be something is wrong

...
I'm a VietNamese and so difficult to buy PCB from tangentsoft. I do it myself.
I don't think something is wrong with my Power or L/R/G ... if have it's only because of my Buffer

Buffer PCB:

I will check my PCB again and will read DC Volts across R10, R24 to find what happen

Thanks for your help!
SLmutmut.

 

[audiofreek]

Hi, I've been thinking of getting one of Tangent's PCBs.. Not quite sure if it will be this or the Pimeta. I want to run it with AKG 271s and Sony MCR-V6s (the latter are pretty easy to drive) and have two questions for those who have built it...

Is it a good match for those phones? Is it not a good match for high impedance phones (in case I change phones in the future, I don't have $$ to change amps too).

Also, I think I saw a list of DIY amps somewhere and I think they listed the cost of this at about $150. Is this about right including everything?

Thanks!

 

[FallenAngel]

Quote:

Originally Posted by MisterX /img/forum/go_quote.gif OPA134's combined with BD139/BD140 output transistors would result in an amp that is brighter and have less bass then a Mini3. How do you figure there is something wrong?

I'll have to double check at home tonight with those opamps, but last time I remember testing my PPAv2 with OPA134, it was seriously not lacking in bass and didn't really have harsh highs (a little thin but not "bad").

I figured something was off because when mine was oscillating the highs were very squeaky and the bass was a mess.

I also never found the Mini3 to have good bass, it was OK, punchy, but not as detailed or sweet (can't really find the word for it, controlled, nice impact, able to feel different types of drum hits) as PPAv2.

SLmutmut: Check the amount of current your amp is using and definitely set your class-a bias properly.

audiofreek: It's a fantastic amp, my favorite for a very long time (until the Beta22). I don't think you'll get it done in $150, but you can try. Also remember that the price doesn't include the power supply.