nice amplifier
bluesmoke
Eventually you could put some insulation sheets
inside that transformer box.
At least around the Mains input wiring.
So called 'double insulation' for safety.
( double because the wires are already insulated )
This is in case some wire for one reason or another would get free
and come into contact with box.
bluesmoke
Eventually you could put some insulation sheets
inside that transformer box.
At least around the Mains input wiring.
So called 'double insulation' for safety.
( double because the wires are already insulated )
This is in case some wire for one reason or another would get free
and come into contact with box.
Thanks.
Yup, transformer box could use a bit of extra protection at some point. Right now I have the box so far out of human contact that it won't get touched nor bounced. Also do a "tug" test to make sure things are soldered well. I find hot-glue a good interm solution as well, webbing between the wires keeps things nice and stable. At some point I'll end up building a nicer looking PS box anyway...
Was just able to get my hand on a pair of 2228's and dropped them in. Works perfectly! (was really worried about oscillation with using a faster chip) In my un-scientific opinion, it does sound nicer than the 2134's, the mid-high end seems a lot more refined. Will stick with the 28's and not look back.
Tempted to try playing with some 627's... in the not so distant future!
Yup, transformer box could use a bit of extra protection at some point. Right now I have the box so far out of human contact that it won't get touched nor bounced. Also do a "tug" test to make sure things are soldered well. I find hot-glue a good interm solution as well, webbing between the wires keeps things nice and stable. At some point I'll end up building a nicer looking PS box anyway...
Was just able to get my hand on a pair of 2228's and dropped them in. Works perfectly! (was really worried about oscillation with using a faster chip) In my un-scientific opinion, it does sound nicer than the 2134's, the mid-high end seems a lot more refined. Will stick with the 28's and not look back.
Tempted to try playing with some 627's... in the not so distant future!
Hello!
I have no doubt it will be all safe when you have finished your project.
So you can confirm Nordic report, that it works well and give satisfying sound output.
I think OPA228 will drive many high quality headphones.
Like Nordic says, even those with lower impedance, 32 Ohm.
OPA228 has got the same max level of output current as NE5534 and OPA2134.
And they are both known to be good drivers.
One OPA228 specifies +-45mA short circuit current.
Using two in parallel would double the drive capacity.
OPA2228, OPA228 are fast, but not as overly fast as some other chips I see used.
For normal gains we needn't never have Op-Amps with bandwidth >100 MHz.
------------------------------------------------------------
Some figures:
NE5534 has done good service in audio for a long, long time:
Slewrate 13V, Bandwidth: 10 MHz
OPA2134 one of leading in Audio:
Slewrate 20V, Bandwidth: 8 MHz
LM3875, the great Gainclone Power Chip
Slewrate 5-11V, Bandwidth: 2-8 MHz
LM3886, the other good audio National Power Chip
Sewrate 8-18V, Bandwidth: 2-8 MHz
OPA228, OPA2228
Slewrate 11V, Bandwidth: 33 MHz
------------------------------------------------------------
So even though having good speed and with high GainBandwidth
the OPA228 is not extremely fast.
Not compared to for example:
AD797
Slewrate 12.5-20V, Bandwidth: 110MHz
OPA627
Slewrate 40-55V, Bandwidth: 16 MHz
OPA637
Slewrate 100-135V, Bandwidth: 80 MHz
---------------------------------------------------------------------
I prefer not to use 'too fast' Op-Amps.
Gives less potential problems in a practical circuit set up.
And I would not often need such high gains that I need extremely High Gain Bandwidth.
10-20 MHz is quite enough.
I'd like to try the OPA228.
Might buy me some. Op-Amps are easy to build with.
But I am more into discretes now: Transistors.
lineup
I have no doubt it will be all safe when you have finished your project.
So you can confirm Nordic report, that it works well and give satisfying sound output.
I think OPA228 will drive many high quality headphones.
Like Nordic says, even those with lower impedance, 32 Ohm.
OPA228 has got the same max level of output current as NE5534 and OPA2134.
And they are both known to be good drivers.
One OPA228 specifies +-45mA short circuit current.
Using two in parallel would double the drive capacity.
OPA2228, OPA228 are fast, but not as overly fast as some other chips I see used.
For normal gains we needn't never have Op-Amps with bandwidth >100 MHz.
------------------------------------------------------------
Some figures:
NE5534 has done good service in audio for a long, long time:
Slewrate 13V, Bandwidth: 10 MHz
OPA2134 one of leading in Audio:
Slewrate 20V, Bandwidth: 8 MHz
LM3875, the great Gainclone Power Chip
Slewrate 5-11V, Bandwidth: 2-8 MHz
LM3886, the other good audio National Power Chip
Sewrate 8-18V, Bandwidth: 2-8 MHz
OPA228, OPA2228
Slewrate 11V, Bandwidth: 33 MHz
------------------------------------------------------------
So even though having good speed and with high GainBandwidth
the OPA228 is not extremely fast.
Not compared to for example:
AD797
Slewrate 12.5-20V, Bandwidth: 110MHz
OPA627
Slewrate 40-55V, Bandwidth: 16 MHz
OPA637
Slewrate 100-135V, Bandwidth: 80 MHz
---------------------------------------------------------------------
I prefer not to use 'too fast' Op-Amps.
Gives less potential problems in a practical circuit set up.
And I would not often need such high gains that I need extremely High Gain Bandwidth.
10-20 MHz is quite enough.
I'd like to try the OPA228.
Might buy me some. Op-Amps are easy to build with.
But I am more into discretes now: Transistors.
lineup
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.