ua739 Op Amp Replacement

[JohnDio]

re: d44

billg here hi all:i was chking the d40/d44 transistors for a crown dc300a-the d44c7,8,9 are rated at supply volts of 60v.but the d40 comes up as an darlington..the data sheet specs the compliment at d44c7,8,9 same specs as the npn.thought i would add this.

probably a bit late with this but, d45 pnp is complement to d44 npn. you can use tip29 and tip30 also. 🙂

 

[ilorev]

I found about 50 ua739 FAIRCHILD, still in the original cue ... they are available to sell individually or in pairs

 

[latala]

I would love 5 739 op amps any idea re price
Trev

 

[ilorev]

Iatala

I have to inquire about UK postage recommended for the quiet price will be moderate

 

[ilorev]

Iatala

UA739PC F7638

 

[latala]

aI use two dca 300 in my home system I just want future proof insurance
Trev

 

[ilorev]

Hi
I certainly haven't forgotten ... I've been to the carrier ... and the shipping costs are high because you are no longer part of the EU ... 9 € ... the costs for 5 ua739 are10 € ... it's convenient for you ???.

 

[dmaumau]

Hello guys,

I would like to pick your collective brain regading this topic again.

The circuit I have here is this

It´s from a Brazilian version of the Kenwood KA-501, named CCE SA-6060.

And remembering ua749 architecture

Well, I am a little bit rusty in my electronics, but it seems that LAG IN/out are not really being used, just not left open, right ?

So, if I would try and use something a bit more refined, would a NE5532 be a step up ?

Obviously it would not be pin compatible, but I could plug in an external pcb.

Should I also modify something in the original circuit, besides removing those 2 caps and resistor from pins 2-4 and 10-12 ?

Would it be necessary to increase/limit current or something like that ?

And if I would like to use OPA 627/637 ?

Thanks in advance for any thoughts.

 

[gullaz]

I found about 50 ua739 FAIRCHILD, still in the original cue ... they are available to sell individually or in pairs

Do you still have some ua739? I need 12.

 

[PRR]

.... it seems that LAG IN/out are not really being used, just not left open, right ?....

Looks to me like both clamp internal points to control response for stable feedback.

And that with this custom compensation, performance is better than any "universal" opamp of the 1970s.

And the tone-control amplifier is usually not a major hit on sound quality.

Is there actually something wrong with it as-is?

 

[dmaumau]

Didn´t even received it yet, but I bought it basically to have some fun upgrading, recaping and so on.

So I´m doing some research, knowing it can sound a lot better than it did back then.

 

[dmaumau]

Well, I just ordered a dual OPA 627 and I´ll try this as an upgrade.

Also ordered some Nichicon Muse caps, but will try one mod at a time.

I´ll keep you guys informed about the results.

 

[latala]

I would like to thank ilorev for sending me the op amps on trust
I have now received them and they will be put to good use I am sure
Dc300 forever
Trev

 

[ilorev]

Hi
I had some doubts about the reception ... too bad your exit from Europe, sending to you has become very complex. This is for border customs, which complicates things a lot ... Thank you and I wish you and your family the best of things ... Ilorev