Hello guys i building some system i need preamp with volume control based on pga2311... I have made some schematics but i wanted that you pro's could check it and tweak it 😀
Inputs will be:
1. iPod, iPhone, Walkman.... 3.5mm jack (MP3)
2. China USB Audio card
3. Bluetooth Headsets like mp3 i think so
4. iPod Dock connector line out (which is not like headphone jack..)
5. FM module based on AR1010
Output Will be TC2000 and TP2050 based amplifier with spec like:
Frequency Response: 20HZ—20KHz(±3dB)
Input Sensitivity: Min. 0.720V; Typ. 0.771V; Max. 0.800V
Channel Separation: Min. 80dB; Typ. 95dB
Input Impedance: Min. 20K ohms; Typ. 22K ohm
This will be Portable speakers and need to get maximum of amplifier but not like you even cant understand words of song 😀DD
EDIT: IC is opa134
Regards
Aurimas
Inputs will be:
1. iPod, iPhone, Walkman.... 3.5mm jack (MP3)
2. China USB Audio card
3. Bluetooth Headsets like mp3 i think so
4. iPod Dock connector line out (which is not like headphone jack..)
5. FM module based on AR1010
Output Will be TC2000 and TP2050 based amplifier with spec like:
Frequency Response: 20HZ—20KHz(±3dB)
Input Sensitivity: Min. 0.720V; Typ. 0.771V; Max. 0.800V
Channel Separation: Min. 80dB; Typ. 95dB
Input Impedance: Min. 20K ohms; Typ. 22K ohm
This will be Portable speakers and need to get maximum of amplifier but not like you even cant understand words of song 😀DD
EDIT: IC is opa134
Regards
Aurimas
Attachments
Last edited:
It looks OK... my only real reservation is limited headroom due to -/+5 volt rails. The output from a CD player... which is one source you haven't mentioned... is typically 2 volts rms at max output which is nearly 6 volts pk/pk. Feed that into an amp with a gain of 2 running on 10 volts dc and it will clip.
The 0.1 uf's could usefully be increased as could R2 and R3 to extend the LF turnover point... unless you deliberately don't want extended LF response.
The 0.1 uf's could usefully be increased as could R2 and R3 to extend the LF turnover point... unless you deliberately don't want extended LF response.
CD player really i think i will not use because i dont have stuff like that at all 😀DD and i have only 11V and i dont know how much to increase if you can please help me because i totally new at audio pre-amp and amplifiers :S
I have looked at the data sheet for for PGA2311 and that places absolute limits on the audio that can be applied.
The outputs from the sources you mention will all be less than a CD player I imagine, but maybe not much less. I would not fit R5 and R6 which will make the opamp act as a buffer with a gain of 1. R7 and R9 can either be left fitted... which gives the option of re-fitting R5 and 6 if you ever did need more gain... or can be linked out.
Also the data sheet recommends a low <600 ohm source impedance so I would drop R8 and R10 right down to around 47 ohms which will give a stability margin for the opamp if there is any stray capacitance that it works into.
The outputs from the sources you mention will all be less than a CD player I imagine, but maybe not much less. I would not fit R5 and R6 which will make the opamp act as a buffer with a gain of 1. R7 and R9 can either be left fitted... which gives the option of re-fitting R5 and 6 if you ever did need more gain... or can be linked out.
Also the data sheet recommends a low <600 ohm source impedance so I would drop R8 and R10 right down to around 47 ohms which will give a stability margin for the opamp if there is any stray capacitance that it works into.
well actually ipod and iphone LO level is definitely lower than 2v, more like 1v4 or something I think
hehe 😀 I have iphone, ipad and IMOD (modified ipod) ipad has pretty standard level LO, but the iphone and ipod are a bit lower. I make LO cables as part of my job, so kinda have to have them. I like the phone and the ipad is a seriously great remote
OPA134 is fine... remember to add a 0.1uf cap directly across it's supply pins to ensure stability.
The gain... only you can decide that. Try it without R6 to begin with. If you need more gain then fit R6 and select it's value on test. I think it will be OK without.
The gain... only you can decide that. Try it without R6 to begin with. If you need more gain then fit R6 and select it's value on test. I think it will be OK without.
Initially leave it out all together... that gives a gain of 1.
If you need more gain... and I dont think you will... then fit a 10k as you show. That will give a gain of 2.
Or you can fit a preset resistor of 10k in place of R6 and adjust until the gain is OK, then take it out, measure it and fit the nearest fixed value resistor.
If you need more gain... and I dont think you will... then fit a 10k as you show. That will give a gain of 2.
Or you can fit a preset resistor of 10k in place of R6 and adjust until the gain is OK, then take it out, measure it and fit the nearest fixed value resistor.
- Status
- Not open for further replies.