bpribadi

Hi All,

For more information and update about this issue, you can read at:

http://www5.head-fi.org/forums/showthread.php?t=80246

Looks like I will use this approach to protect the buffers, for my headamp that I'm going to build soon:

Bram

For traveling, I think portable hd base player would be nice. You don't have to bring or change CD.

So far only iPod has the lossless compression compatibility. For sound quality, I would say it is the same as normal PCDP. I'm not MP3 fans, so lossless compression is a must for me.

For cans, it would be earbuds or clip on. For clip on, my favorite is ATH-EW9 (see my avatar). Earbuds, there are a lot of good ones out there. My myself, I have sony MDR-E888. Audio Technica also has some good models. Or KOSS the plug for cheap and good option.

PCDP, I have iRiver and Panasonic, so far I like my Panasonic SL-CT-810. Good sound and very impressive battery life. And it is very slim as well.

Thanks for the tips tropicalrips! I have just ordered the samples as well

Need your advice how to solder them to a brown dog adapter

Hi experts! need your advice...

On Tangent's page about buffer:

http://tangentsoft.net/audio/ppa/amp/tweaks.html#par-buffers

It said there that HA-5002 sounds so good because it has no output current protection. Internally true, but I saw in the datasheet, that externally, we can use resistor to limit the output current, thus protect the buffer from short circuit.

My questions:

1. Does PPA use this RLim to protect the buffers? Well I didn't see it on the PPA schematic.

2. Will there be any effect to the sound quality by using RLim to protect the buffer?

HA-5002 datasheet:

http://www.intersil.com/data/fn/fn2921.pdf

read page 4

Thanks!

http://www5.head-fi.org/forums/showthread....4844#post904844

Hi digi,

What happened with your tube amp? Would you like to share with us how it sounds?

http://www5.head-fi.org/forums/showthread.php?t=75693

also tried the AD8620 which is what i'm using...

Hi Tropicalrips,

May I know where you got the AD8620 from? I'm also looking for AD8610 or AD8620 in singapore.

Thanks!

As Always, nice work Digi

What are those big blue things? Rechargeable batteries?

The thing is, are there any other cans out there ( i think i kinda give-up on ear-canals ; too intrusive and troublesome at times ) which are closed and can better the PX200s?

For my taste and according to my experience, nothing come close to the ATH-EW9 wood 'clip on' for the price range SGD 200.-.

I tried PX-200, they are not as open as the EW9, and EW9 excels in all sections, better and bigger bass, warm mid, open sounding highs. Anyway it is not fair to compare both of them because of the price different.

If you guys want to 'group buy' OPA627 or 637, please include me in

I wonder if Digi01 can help us to buy the chip from China, it is much cheaper there

Personnaly I would like to try the OPA637, since it is faster than the 627, and I can live with it >5 gain requirement.

In fact my 21 months son likes it also So he has "abused" the headphone... you know, pull the cable, etc. And I found no problem so far with the construction. The clip on is flexible, not easy to spoil it. The worst, it will bend, but you can bend it back. Not like plastic, once broke, difficult to repair.

To me the construction is quite good and durable.

Considering the price of the OPA627, probably you can modified the circuit a little bit, replace the buffer for each channel with HA3-5002 buffer, or BUF634. So you only need 2 of the OPA627 and a pair of buffer.

I guess it will become the "platinum edition" of the amp. The one with cheaper Op-Amp can be called standard edition

My guess would be that your gain is too high. Try lowering the gain until you get normal listening volume at about 75% of the lineout volume (just an anyhow suggestion, so that u get and idea)

The gain is 5.7, so I guess it is not too high, but the line out of my PCDP (iMP-150) is not clean (with hiss). When I got time I will post my theory why we need volume pot, based on my experienced.

Hi nakedtoes,

Just want to share my 'little' experience with PX200, EX71, & ATH-EW9.

Firts, let me describe my taste. I like recordings with good sound stage and rich in details, mainly vocal, jazz, and classical. So I'm not the rock or heavy metal fans. I like to hear the very subtle details like the singer breath, the squicking sound of guitar, and other ambience sounds.

My impression of those headphones (I tried with various sources, such as PCDPs & iPod):

PX200, not bad for the price. The bass is a little shy, and the mid and high are less open than my ATH-EW9. Good design.

EX71, big bass when properly pluged, the high is too harsh for me. Sorry to say that the mid and high sounds cheap (compare to my old MDR-E888).

ATH-EW9, so far the best headphone I've ever heard for the price range. Often beat big headphones that twice more expensive. So if your budget is around SGD 200.- and don't mind with clip ons (it is very comfortable, more comfortable than earbuds), I recommend this wodden can. It sounds very natural, good bass, and has a very lively sound with good sound stage.

So far all Senn's that I tried didn't suit my taste (PX200, HD650). They sounded flat and not as lively as AT. It also depend on the source, headamp, etc. But I tried them with good headamp and decent source.

That's my 'little' experience, please don't take it too seriously, everybody has different taste.

bpribadi,maybe I can help you get the good case.

such as this OEM case,the size is 100x60x200mm,pre-drill vol+headphone out jack+ac power+input.

Thanks a lot Digi! I will consider your offer

At the moment my next headamp is still in concept, so still long time until I need a casing.

Thanks anyway!

Bram

I'm surprised for I own a Panasonic Sl-CT790 and connected to Porta Corda II via line/optical output but I detect no hiss at all. In fact, connection via headphone out results in lower gain, higher noise level and also a somewhat compressed sound - in terms of soundstaging dimensions.

I mean, if there is no volume on the headamp, I can hear hissing sound when using iRiver volume (their line out is volumed). When using headamp with volume, no hissing sound heard. This is my experience, because I think iMP-150 line out is not so clean, so the hiss level will be audible when amplified.

Probably your SL-CT790 is cleaner than the iMP-150.

Huangyong wrote:

...though it's expensive ( $40+ in farnell ), but we have a lobang king here, can get it for around half price.

Hi Huangyong,

Where? where? I want a pair to

Does your 'lobang' can get the OPA637 as well? If you don't mind, please let us know where to buy OPA627/637 with half of Farnell price

Thank you so much!

Bram

Hi Digi, you are very fortunate to be able to design your own casing

I wonder there is such a place in Singapore where I can order wy own casing with a reasonable price (SGD 20 to 50, depend on size).

I use CAT5 wire for jumper and hook up. So far satisfactory, and cheap

Try Farnell, item code BS3G210 by Brand-Rex. silver plated, PTFE insulated.

Try search this order code: 3221131, then it will leads you to the details.

http://international2.farnell.com/SG/Welco...egistered.jhtml

WIRE PTFE 19/0.15 A BLACK 25M

--------------------------------------------------------------------------------

BS3G210 Type A19/0.15mm (0.338mm<SUP>2</SUP>) 22 AWG

BS3G210 Type A19/0.20mm (0.597mm<SUP>2</SUP>) 20 AWG

BS3G210 Type B7/0.20mm (0.22mm<SUP>2</SUP>) 24 AWG

BS3G210 Type B19/0.15mm (0.338mm<SUP>2</SUP>) 22 AWG

my fav op-amp with this board is the opa2228, this was very surprising to me as the chip didn't sound good on a Cmoy or A47. The opa2228 sounds the most balanced of the 3 op-amps i tried, with good details and mid-range

Hi Tropicalrips,

I thought you guys built an A47? So what circuit is good for the OPA2228?

I would like to try one, let us know when you guys ready with the 'production model'

Canon G2.

Well, I use line out of the PCDP. My iRiver line out using the same volume as the headphone out. So this is only works with iRiver, other brands PCDP has no volume for the line out, only iRiver use volume for the line out.

With my Panasonic SL-CT-810, I have another small box with blue ALPS as the volume pot. This small box I use as the interconnect between the PCDP and the headamp line in.

Using the PCDP line out volume is actually not a good approach. The headamp will amplified the line out hiss. Since hiss sound of the line out is the same level regardless of the player volume, so I can hear hiss during silent, or low volume level. To solve this, I need pots for volume, and set the player volume to max, so the ratio of the music signal will be much higher than the hiss, and then use the pot as the secondary volume. This way the hiss level will be reduce when we reduce accordingly by the pots. To my case, no more audible hiss.

It just happened that I have that hammond casing for a very long time in my drawer, so I want to make use of it. And because of space constrain, no space for pot. But next time I won't build headamp without volume pot, I have learnt my lesson

Thanks Digi! It is one of the standard Hammond die cast casing. You can get it from Farnell.

Actually I was about to ask you where you got those casings you used for your headamp. I saw some of your threats in head-fi, and all of your casings are very nice.

Bram

Hi! Anyone know where to get AD8610/20 in Singapore? Farnell and RS components don't have it.

Also, is there cheaper shop to buy OPA637? Farnell selling at around SGD 40.- per piece.

Thanks!

Hi Nakedtoes,

Last month I built a CMoy, also to try the difference a HeadAmp can give. I built it with OPA2134.

I use 2 PCDP, iRiver iMP-150 and Panasonic SL-CT810, with ATH-EW9 headphone. The sound different is quite evidence, my wife, my brother, and some friends all of them can tell the difference, that means it is not subjective.

OPA2134 has a good bass and midrange for it's price, but not enough soundstage and details for me. I ussually add some bass when connect my headphone directly to the PCDP, with OPA2134 it is not neccessary to add the bass anymore, I can play it flat, the bass is enough for me.

So my first CMoy has drove me to build a better amp. I suggest you try a simple CMoy and try the difference. Now I'm preparing to build PPA's like (without PPA board) headamp, and some other with LM6171.