sorry to have ask, is there any tutorial for newbs to make an portable amp for mp3 players and etc?

i've searched the forum, hardly find one, any guidance from sifus here?
please do not flame me

tangentsoft.net/audio

Look for the CMOY article.

And basically the older thread has more information for newbies so you have to PM scotty to get the older compilation.

Pretty bad move to baleet the old thread IMO.

guys recently i build 2 identical CMOY amps,the problem is when i connect the battery,the battery heats up and r-side is a lot louder than left-side,i have to max the volume on the knob to get decent sound,wat m i doing wrong leh?plus help i hav almost 0 electronic knowledge....

amp 1




amp 2




above is the image of under side of my pcb board and top view......help sifus!!!

what opamp?

Recheck soldering and reflow it, make sure you do not short V+ to V-

This post has been edited by LittleGhost: Nov 11 2009, 03:02 PM

anyone done a tube pre-amp project before?

i'm planning to reverse engineer one... i'm in the stage of buying the components...

just a quick question, is it easy to get the tube female socket to hold ECC83/82 tubes? if yes, roughly how much will it cost?

When I was at NIXIE in Jalan Landak/Pasar last, I saw some tube sockets there. Don't know how much they will cost.
Care sharing the amp model that you're trying to reverse engineer? What would be your anticipated co$t?

I never built the tube version power amplifier. Latest project I have made at 2006 is CLASS A current feedback amplifier with emitter follower (0.98 x gain) plus high frequency Bipolar type.

well for the input buffer I have re-design the Class A Doz preamp, so i will have a big gain with a regulated supply of 72Vdc.

Well this setup make the sound more in natural way (without any filter). The sound more bright. The Class A with a current feedback have a lower S/N ration as i concern. Even without any casing, it really hard to find a Humming sound.

For the modified Class A DOZ preamp, the bad is ,I will never turn it off or the sound will litle shy..

Hopely I will make a tube type amp someday...

What type of tube socket you need, chasis mount or PCB mount. For ECC82/83 it need the 9 pin tube socket.

this is the pre amp i will reverse engineer; at this link: http://www.hometheaterhifi.com/volume_8_2/...ier-4-2001.html

the tube socket i will not mount it on PCB. i will translate the PCB trace into a point to point wiring using copper wires...
cost, should be around rm100 plus not counting the ecc83 tube cost.

This post has been edited by ora-ito: Nov 13 2009, 10:55 PM

I am fascinated by tube amps.. Used to have one China made headphone/preamp tube.. but sold it off a while back.. too darn hot.. could definitely fry an egg!(maybe two!)

ora-ito,
If thats the price, well I want to make one too!
BTW, any particular reasons why you chose this amp?
There are other simple tube preamp to build...

This post has been edited by jazzy939: Nov 13 2009, 11:51 PM

well, its because i own the actual unit. it gave me some problems on each channel.
i managed to troubleshoot and repair it. so at the same time i took the time to understand the circuitry and took some measurements during my troubleshooting.

this tube pre amp brand is very well known in singapore coz it was designed by a singporean musician cum audiophile enthusiast. a totally musical piece of equipment and can be compared to very high end pre amps.
Brand new pricetag is SGD1.4k if you have read the link i posted.

however that price i quoted does not include the ecc83 tube.
so far i have about 12 tube collections ranging from china to russian, mullard & telefunken
they can cost from rm50 to rm350 per tube that's the catch hehe

here is another link for more Q&A on this pre amp brand: http://www.echoloft.com/soulofmusic/divafaq.htm

This post has been edited by ora-ito: Nov 14 2009, 12:09 AM

ora-ito,
thanks for the update and links!
keep us posted...

I found that most audiophile here more on the amp for the headphone. I am willing to build one but as I know if the sound are flat setting the phone will be sound from the headphone sound very dully. Maybe I never used the hi fi type for the headphone.

So in my mind maybe the amp for the headphone must be in solid state Class A using a MOSFET, (great respond and still cheap because it just a few miliwat). Next it must have a good pre amp (boosting bass and treble). For the component it can be made from highest quality one. Next remove all bipolor type capacitor with NP and each power supply for the power caps must be bypass with 100nF MKT capacitor. the power supply must in regulated (reduce humming). More the contruction for positioning all the sub section (power supply, pre amp, and etc) must follow the rules (Please read cook book for designing power amp from JHL).

I hope I can find my time to build this and if can I finish I will able to show it to you malaysian fans...

Keep us posted, nanhifi!

Hi, this could be the wrong place to ask but since it's the DIY thread, I was wondering how to differentiate between amps, as in characteristics/sound/brightness based on the specs alone. Not everyone can go an audition amps but it would be good to have a rough idea based on the amps specs.
Thanks in advanced.

Never on the spec. Period.

Wow, really? Ah damn. Then how to know? Reviews? Audition them? Sigh, I'm kind of an impulse buyer. Sure kantoi after I audition.

Google for reviews.. audition yourself if possible. In the end let your ears(and wallet) decide.
I have equipments that I buy based on 'value for money' , its a gamble but its part of the experience process..

wow, nanhifi is here....welcome bro....

I guess you still stick with your solid state transistor world....how's the Bee amp?

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Added on December 13, 2009, 12:26 pm

This post has been edited by gabanyayaya: Dec 13 2009, 12:26 PM

There a lot to tell here, I just cannot tell you what is the best for your ears.

As for spec, even in a solid state, intergrated, vavle or etc the spec just a spec, what the true is our listening behaviour.

For me, I look for the class of the AMP (class A, AB or D) next the topology (Cureent Feedback, Voltage feedback, symitrical, balance, Bi-Amped, Emitter follower output stage, Collector Follower Output stage and many more that will not enough time to write) then the component that been used. Minimum the caps are betters and the resistor 1% or macted pair transistor, MKT caps with all the polar cap bypass with a small film caps (cap make non linerity in circuit).

I like class A but it will get a low rate of RMS but still not a big diff then the Class AB which is greater the RMS.

The watts rating basic on 1Khz rate not at other fq, (mostly great and high brand amp will tell this spec)

The most problem in class A is the bass sound will lack a bit but in high end amplifier this is not true (well get yur bugdet to 100k RM). The great is the class A have a 2nd order lower then other classes with a minimal component used(same applied to tube or vavle amp)

The most moderate amp will used a type of voltage feeback , rarely a current feedback. (most case the CFA will be in the top list of high value amp) but even so, the VFA that have a good design still produce good sound.

Most of the vavle and single ended class A topology will just a few watts (RMS) but still found to be like a 100W. We will only can get a differance when it most higher then 1dB (pro listener) or more normal to 3dB diff.

From the calculation based on watt (RMS HERE NOT PMPO OR OTHER) the 120 W will only diff near 2X of 30W amp (2db).

The spec like the bandwidth, i will choose from range 10Hz to 100Khz which is mostly not in most the normal market amplifier. This can be build using a CFA type. My theory here is the sound it self have a spirit.. Well even we not really here Fq low then 20Hz or higher then 22kHz (Me only at 21Khz) but we can feel it, like an earth quake or sonar we feel???.

But normal used it will have a good frequency respond from 20Hz to 22Khz or 30Khz is enough. +- 0.5dB.

More if you like big bass in rock or pop song it will have to take the damping factor value. Use a bigger cable to achive this. maybe not all spec will be shown.

Next is the IMD and THD. I rarely take this as a top piority since the tube or vavle amp have a big THD but mostly it sound better this due to the what we call sonic and soundstage phenomena. But most modern amplifier will have a low THD but not more brand showing the data for IMD.

But all of this will be gone if you willing to make 3 way 24dB electronic amplifier stage. This will be the best system that i ever hear in my life. But it will cost you most near RM20k with a accurate tuning. It will need at least 5 power amp or more (sub woofer will be need a bass management to get the below 15Hz tuning) so it will be a full range set. Tweaking will take year in this thing... Welll my friend manage to do that as for me i love more simple single mono block amplifier that I design on my own with a pair of analog 2way bookself speaker. Get headace? Ok I simplified

1- Look what type are you love to listen, soft or hard type, rock or jazz or all of it . Most british amp are soft.

2- Look for the class, The class A is the best for vocal or opera or jazz but not the rock or pop in range of 30W. Since this amp high power class A (X250) are pricy and hot massive weight it will be high budget bro.. Next if class AB high current, this is same as class AB amp but the Q current is set more then 300mA or 1A (near true class A). This amp will hot with lot of cooling metal but not as hot as true class A (or CLASS AA).
Next look for the class AB . This most in normal price intergrated amp.

2- The amplifier RMS must be higher then your loudspeaker rate . Lower RMS amp tend to damage the loudspeaker more then a higher one. This accour from distortion or spike or clipping factor. A range of 100W to 250W will be good amp. But for class A this not happend were it will be soft clip when it reach to the highest or saturated position.

3-The THD, look for the lowest you can get.

4- Listen and make yur own choice for all these. Sometimes even a good spec have a worst sound..... But this will only a guide.. I will test the amp at the full power to get the picture. Most amp will worst at higher sound (this will not so high when the softer amp type) if you feel that the amp make your ear sick.. maybe need to find another one. But dont blow your ears god give.... hopely...

Hope you get the picture.. sorry to long write here.. so much to tell but nobody to tell...

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Added on December 20, 2009, 11:26 pmto gabanyayaya,

My bee amp, still on the run and I will need to re modified a lot. Still as same solid state . The cable, the heat sink will be need to upgrade, or change it to other topology(looking for a high power class AA current feedback amp or balace type). So much to do but not now.. Busyyy workingggg everyday..

Thank, How you know me bro??

This post has been edited by nanhifi: Dec 20 2009, 11:26 PM