Plan to make a cmoy and a few cables

definitely a good solder...try to get GOOT or HAKKO 30w shud suffice to do the job

This post has been edited by CV6149: Apr 17 2009, 03:06 PM

I pretty much agree to that!
A soldering iron stand would be nice to have. Small pliers, cutters, phillips screw drivers, jewellers screw driver set, small magnifying glass, a multimeter(analogue/digital), a variable bench power supply, a toolbox for sure to keep all your goodies...

I have a circuit ready for PCB production. Can I know what software to use for population ? any company can help me with the design of PCB ?

try diptrace. it's free and has plentiful features.

I'd suggest making the PCB on your own. It's better this way because you can do whatever you want to it.

Out of curiosity, you're building an I/V stage?

Yeah. It is the simplest IV stage that ever built. first 2sc2240 for IV and the second 2sc2240 for buffer.

I have seen and heard complicated IV with > 50 transistors. However the sound is no better than using 2 transistors and other assorted component. It is current conveyance with coupling cap Mundorf supreme (cant afford VCAP TFTF) with Roederstein 1837 bypass. Then IV resistor Vishay precision with 0.01% accuracy and 4x3300uF ELNA cap pool. filtering using Jantzen air core choke. this assorted item is coming soon from partsnexxion.

"" quote from ECDesign ""

The output stage appears to work best when loaded with a choke. Push-pull, (cascoded) current source, and many other configurations failed to achieve the clarity produced by a choke-loaded SE buffer, and produced much higher measurable noise levels at the buffer output. I now use small 1.6VA toroidal transformers (2 x 115V primary, secondary of 2x9V are not connected). These have a DC resistance of approx. 2 K Ohm (primary windings connected in series). I connected this choke between the emitter and -12V. (so the output buffer runs on +/-12V). This saves buying a 500R bulk metal foil, and sounds much better.
""""""






This post has been edited by ccschua: Apr 19 2009, 10:35 AM

ccschua,
looking good!
I would go with LittleGhost recommendations. I personally use Diptrace. The learning curve is short (to me) and making your own PCB give you much freedom, circuit layout, size and that 'satisfaction'

with a circuit this minimal, I'd suggest super compact point to point on a perfboard.

It'll probably be much more cost effective than using PCB. I don't see how going full PCB would be much better than a compact point to point for this.

see your point. isnt there some advantage using PCB for double layer with proper ground plane execution.

I have a question. The below is the IV circuit that I am executing.



IDac is always zero being the virtual ground for IV Conversion. In addition to this circuit,

Instead of using 100k ohm, I am using 10k ohm to give a f 3db lower than 20Hz. This output feeds the tube amp with a 10k pot in parallel with a 470k grid resistor.

I see something wrong this circuit in the sense the input impedance for tube amp is too low. so when couple with the 10k ground leak resistor, I am having on 5k which shifts the f 3dB to 40hz?

the detail circuit is below.

This post has been edited by ccschua: Apr 19 2009, 12:20 PM


Attached thumbnail(s)

I don't understand your first question, what do you want to achieve with the R4? It's there to provide bias and the adjust gain. Just stick with the stock values.

You should use 100k Ohm instead of 10k Ohm if you are using a 10K pot. This way you ensure minimal loading effect and the 10k pot dominates the total resistance. If you used 10k, you'll only get an equivalent of 5k resistance, which means a a shift of cut off frequency.

Went to singapore. Look at the martin audio, well audio and larry plus adelphi.

at martin, the old lady was working on super tweeter, casing made of lighting transluscent glass. the sound really improve the high, making it more lively. That old lady mainly made the Martin class tube amp as well as speakers.

adelphil was more high class venue for expensive stuff like fm, mcintosh, MBL,etc.

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Added on April 22, 2009, 9:09 pmAfter R4, there is a 10k pot in parallel to the 470k resistor grid (to ground) inside the amp. What the cap sees is R4 and a 10k pot (neglecting 470k due to parallel).

That means the cap sees R4, RCA cable which assume inductance and cap is minimal and a 10k resistance to ground.

meaning the amp input resistance by right should be large enuf to provide independent loading to C2. if amp input resitor is high, the cut off frequency will depend on R4. If amp input resistor is low, then R4 has to be changed to suit the f 3dB. what is your thots.

However providing too large a R4, the tone phase shift will be significant at frequency below few hundred hz.

This post has been edited by ccschua: Apr 22 2009, 09:09 PM

emm 1 of the caps looks like fake.......
correct me if im wrong........

I wanna ask all DIY kings a question. Oh for once please answer this question, you know who you people are..

After calculating all the cost including shipping, drilling tools, casing and etcssssss (I'm forced to emphasize on the "etc" cause there is just too many hidden cost. You wouldn't find out until you take the time to sit down and calculate.) I've come to a conclusion that DIY a Bijou futterman www.cavallieaudio.com would cost me approximate 1k. With that sum of money, i could have easily top in a few more hundred bucks and get a woo audio or darkvoice which IMO has a very good synergy with my current headphone HD650.

It has been long debated that given a DIY 1k amp, it is on par with a more expensive amp. I need opinion before i start ordering parts n yada yada. I mean, seriously.

-S-

Nope, R4 will not affect the RC filter formed by C2 and the output 100k resistor.

Assuming your IV stage uses the common base topology, T2 is a emitter follower buffer that removes all influences of the previous stage impedance. (impedance transforming effect).

In any case the only thing you have to worry about is the 100k being stiff enough so you don't load the next stage too much. At this point, you should choose which part of the impedance that dominates the total equivalent resistance.

EDIT: lol huge pics.

This post has been edited by LittleGhost: Apr 23 2009, 09:28 AM

I am interested to know which is the fake. I can get back to him for the 'ransom'

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Added on April 23, 2009, 7:40 pmActually R4 I have changed to 21K4 due to phase distortion at low frequency. (phase plot at low freq will show) R4 is also called the ground leaked resistor in this case is paralllel to the load resistor Rs (which is the amp pot). So the sound does depend on R4. After I put in 21k4, I am much more happy. in fact I can really hear the realisms of music now.

The greatest workhorse is the GAD-viva. It is really vivacious and neutral. the guitar and cymbal is so 'REAL' now.

When the Mundorf Supreme comes, it will be a T day.

This post has been edited by ccschua: Apr 23 2009, 07:40 PM

my guess is the 35v beside beside tonerex 42v...
I cant seem to read what brand is that? NCC?

Its very personal i think . to me DIYing stuff give you a feeling that money can't buy. Its about hobby. just like fishing.

I don't get it, how is the R4 in parallel to anything? I thought it takes in signal unattenuated from the DAC output?

Anyway, R4 determines the total bias. Decreasing it increases the current through the resistor. It might explain some of the "heavy bias upgrade" effect you're experiencing. How about using an active CCS load instead?

The aim is to use as least component as possible. Less is good. CCS or offset the IV has tried by many like petra rodja and Jocko which is good but more component count.

R3 is the bias for T2. R3 is not seen by C2. C2 sees the R4 (bleeder, serve to avoid C2 drifting, or else the cap can not discharge) and the Load impedance in the amp (lets call it R-load).

Do we care about R4? No, provided C2 > 1/(4 x pi x R4) and noise is depending squre root of R4. so too high a R4 not only create phase shift but noise too.

This post has been edited by ccschua: Apr 24 2009, 12:36 AM

They look a bit like Cerafines or some type of Elna to me, though I think Cerafines are usually a brighter red.

Chemi-Cons I believe have the white polarity stripe.