@Freddymac2 no problem - my threads are to pay back AK and all those who provided so much information.
yes, you will have to use a larger transformer to provide more current in order to use any other
opamp than the original . the middle one in the pix in post 9, shows a Hammond 160f34
which is 4.4VA which I calculated to be enough. check the Hammond pdf for secondary
voltages. you can up the VA for more margin but NOTHING (I tried as you can see)
would fit. (original was 3.4VA so I think so one more amp would have provided approx.
200 ma more for each opamp - more than enough).
here's the problem the DC power supply is built around the traces for that transformer,
if you just have an external transformer then you'll have to snake its wires back into the
chassis using hopefully shielded wires for hum control. otherwise you could simply
build an equivalent power supply with more "jazz" (like voltage regulators, etc)
and then cable back the power supply. if you then pull the old transformer there
won't be any of its PS circuitry to worry about. I would be careful of the grounds
both units should not have a third (earth/AC) ground to worry about
(multiple grounds in amps and such are beyond my patience maximums)
next up. socket those puppies - follow the tips and orientation from above.
use a white dot of paint to note pin 1.
now for the exciting part, you can now use any opamps since the 1970s
like the ones you mentioned. I would advise reading the opamp specs
for cautions.specifically their minimum gains (some of the opamp stages
in the DQ are unity (1) gain buffers so any opamps that need to be circuits
where gain is say greater than 5 can't be used. second, you could isolate these
and keep the originals or use different opamps that are stable under all conditions
check here at AK and diyaudio for those threads that talk about opamp upgrades
and follow their discoveries.
I would also advise you to look into putting 1) caps from V+ and V- to ground, 2)
caps across V+ and V-, these are bypasses and will prevent any other problems.
do note these are not absolutely required (many commercial units like the Hafler
DH100 don't have them ) but are recommended. you can do this while you are socketing it.
note: I didn't do this. and you can use the smallest wimas either mylar
(MKP I think) or polypropylene (MKT I think). solder everything at once.
I would have loved to use the 4562s.
PS. PM me, you can have my two extra transformers. free.
yes, you will have to use a larger transformer to provide more current in order to use any other
opamp than the original . the middle one in the pix in post 9, shows a Hammond 160f34
which is 4.4VA which I calculated to be enough. check the Hammond pdf for secondary
voltages. you can up the VA for more margin but NOTHING (I tried as you can see)
would fit. (original was 3.4VA so I think so one more amp would have provided approx.
200 ma more for each opamp - more than enough).
here's the problem the DC power supply is built around the traces for that transformer,
if you just have an external transformer then you'll have to snake its wires back into the
chassis using hopefully shielded wires for hum control. otherwise you could simply
build an equivalent power supply with more "jazz" (like voltage regulators, etc)
and then cable back the power supply. if you then pull the old transformer there
won't be any of its PS circuitry to worry about. I would be careful of the grounds
both units should not have a third (earth/AC) ground to worry about
(multiple grounds in amps and such are beyond my patience maximums)
next up. socket those puppies - follow the tips and orientation from above.
use a white dot of paint to note pin 1.
now for the exciting part, you can now use any opamps since the 1970s
like the ones you mentioned. I would advise reading the opamp specs
for cautions.specifically their minimum gains (some of the opamp stages
in the DQ are unity (1) gain buffers so any opamps that need to be circuits
where gain is say greater than 5 can't be used. second, you could isolate these
and keep the originals or use different opamps that are stable under all conditions
check here at AK and diyaudio for those threads that talk about opamp upgrades
and follow their discoveries.
I would also advise you to look into putting 1) caps from V+ and V- to ground, 2)
caps across V+ and V-, these are bypasses and will prevent any other problems.
do note these are not absolutely required (many commercial units like the Hafler
DH100 don't have them ) but are recommended. you can do this while you are socketing it.
note: I didn't do this. and you can use the smallest wimas either mylar
(MKP I think) or polypropylene (MKT I think). solder everything at once.
I would have loved to use the 4562s.
PS. PM me, you can have my two extra transformers. free.
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