alvin2038

yeah i wasn't able to fit it into that small casing so my cmoy2 now sitting in a namecard box still using liquid paper cap for my volume knob need to find time go buy a nice knob for it

where did you get that volume pot from? i was looking for it. available at farnell?

I got the volume pot from Tangent at

 

http://www.tangentsoft.net/

 

Price is not too bad but you need to buy other stuff and use Paypal to pay. Service was very prompt, less than a week to get it.

ok..i'll go check it out. thanks.

I managed to fit the input and output jacks and the vol pot with built-in switch into the front panel. But you really need the pot with built-in switch otherwise they won't fit.

hey.. very nice!

where did you get that volume pot from? i was looking for it. available at farnell?

oh that reminds me..i need to get a vol knob. right now my cmoy2 installed in a name card box with tippex cap for a knob

You have to put the jacks on left side of the casing. Front for on-off switch, vol knob and led.

thanks! mine look like the pair on top left. do you have the part numbers for the other 2 pairs? i might order from farnell...no time to go sim lim tower these 2 weeks.

quick question..

any suggestions for audio input and output sockets? those i got looked ok until i tried to fit them into the suggested hammond 1593p case. one of sockets is being obstructed by the lm6171 and its dip socket. putting on the side might be possible but i think also tight squeeze.

i'm wonder if i can get a smaller socket. those small ones i found so far are non-stereo jacks.

can anyone explain the diff between the opa2227 and opa2228? from what i can see from the datasheets, opa2227 bandwidth is 8mhz, 2.3v/µs while the opa2228 is 33mhz, 10v/µs.

from my earlier tests with the opa2228's, i reported some bad distortion with the bass esp at higher volumes. i replaced the opa2228's with opa2227's and there is no distortion now. could the distortion be due to the bandwidth of 33mhz? the opa2134 is also 8mhz.

anyway, i'm really enjoying the amp with opa2227's. nice!

From http://tangentsoft.net/audio/cmoy-tutorial/tweaks.html

thanks

thanks for the inputs guys.

not sure its the battery since the bass is fine when i switch back to the 2134's.

increase caps to 470µF? you mean the ones at c3 and c4? i could give that a shot but need to get some of those caps first. ok..pardon my ignorance cos not familiar with this stuff. how will increasing the caps help?

i tried using opa2228's in place of the opa2134's and found that the bass tends to get badly distorted. do i need to change any other components if i want to try the opa2228?

i took the lazy way. ordered most of the components online from farnell with free delivery

finally got off my butt and assembled the cmoy2. so happy that it works on my 1st attempt. made 1 boo-boo...forgot to add a switch to this... now to put all this into a case..

jasonhanjk, your assembly instructions are very clear. thanks!

well...if opamps are not pin-compatible and i want to try out different types, i would need to resolder or rather redirect some of the pins right? sorry ah...a bit confused 

No, there are many opamps available which are pin compatible with the OPA2134, just need to make sure by checking their data sheets. I advise you read bpribadi's review of opamps. If he said the opamps are dual channels in one opamp chip, they will be compatible. But note that not any dual channel opamp can be used, just those that has been tried by the more experienced people. (I have heard that bipolar opamps are more likely to have problems.)

ok thanks for the info. i will start with the opa2134 to get a feel of this first. adventures will come later

Check input jack connection, got fully insert?

 

Try pluck all opamp out leaving one and do listening test.

 

Or maybe you connect your input and output wrong again.

 

 

Alvin, why need resoldering on the sockets?

well...if opamps are not pin-compatible and i want to try out different types, i would need to resolder or rather redirect some of the pins right? sorry ah...a bit confused

pardon my newbie question. i know nuts about op amps and all this stuff but would like to try putting one together.

 

you mentioned putting the opamps in sockets makes it easy to test other opamps. are the pinouts the same for all opamps? or maybe i should ask what other opamps are pin-compatible with the OPA2134PA?

All opamps are not the same, you have to read a datasheet to find out whether their pinout are the same.

 

Try search LM6171 and OPA2134 datasheet and see for yourself...

hmm..so not exactly just straightforward replacement huh? some resoldering of the sockets might be required? ok i'll go look up the datasheets. thanks

pardon my newbie question. i know nuts about op amps and all this stuff but would like to try putting one together.

you mentioned putting the opamps in sockets makes it easy to test other opamps. are the pinouts the same for all opamps? or maybe i should ask what other opamps are pin-compatible with the OPA2134PA?