[MikeW]

Hey plonter, the AD743JN (you need 2 of them) and the adapter are a pretty big upgrade over stock imho. For awhile HiFlight (forum member) was selling a nice kit that included the adapter, opamps, and longer screws + washers (you have to raise the top slightly). I doubt he's still selling them and the AD743JN is hard to find now. I would not say it is warmer then the stock opamp, but it's certainly more Hi-fi. Better soundstage and clairity, it's not subtle at all. Give it a shot if you can find the combo somewhere.

I've gone back and compared to the original Opamp, and found it unbearable. There's no going back.

 

[somestranger26]

Correct that AD743JN are no longer made, but you can substitute them with Digi-Key - AD743JRZ-16-ND (Manufacturer - AD743JRZ-16) if you solder the right pins to the SOIC -> Dual DIP adapter. AD743 | Ultralow Noise BiFET Op Amp | Operational Amplifiers (Op Amps) | Amplifiers and Comparators | Analog Devices gives the pin assignments you need, 9 of them are unused which is why you can do this. I haven't done this, since I sold my EF1 but I found a thread somewhere on here a couple months ago documenting the "mod" but I can no longer find it.

 

[gnostic19]

i had a vendor recommend these:

I have a couple excellent Radiotechniques on hand, 1960s vintage - they are $39.50 ea.

I also have the excellent RFT (German) tube for $24.50 ea.

I have this as well...(1) 6189 RCA black vertical rib plate 3 mica square getter, NOS in a white box, excellent gain/Gm match and good section balance! $34.50.

Any thoughts?

 

[Youthanasia]

Quote:

Originally Posted by somestranger26 /img/forum/go_quote.gif Correct that AD743JN are no longer made, but you can substitute them with Digi-Key - AD743JRZ-16-ND (Manufacturer - AD743JRZ-16) if you solder the right pins to the SOIC -> Dual DIP adapter. AD743 | Ultralow Noise BiFET Op Amp | Operational Amplifiers (Op Amps) | Amplifiers and Comparators | Analog Devices gives the pin assignments you need, 9 of them are unused which is why you can do this. I haven't done this, since I sold my EF1 but I found a thread somewhere on here a couple months ago documenting the "mod" but I can no longer find it.

I got the ad797brz soldered them on an dip8 adapter.
Then put them on a dual dip8 adapter.
All from digikey.

 

[Youthanasia]

pictures:

sorry about the dust

 

[Youthanasia]

I have the OP275, AD797BRZ, BB OPA 627AU, BB OPA 627BP, LM4562NA,

Tried audiogd, sun moon and earth. All three gave me hissing, or no sound after a while.. Not sure what was the cause. Talked with audio-gd. Connected earth to GND of EF1... all the same..

Now I'm looking for some new op amps to play with..
Any suggestions?

 

[MikeW]

i'd like to experiment with other op-amps as well. Though im not willing to cut my EF1 up

hehe. It would be nice if there was a single chip op-amp like the OP275 that performed beter then these dual ad743's. From what I can tell there's not been a whole lot of op-amp rolling done by EF1 owners. I don't even know what kind of op-amp it requires or how to get a list of compaitible OP-amps. I think it's a dual channel op-amp, which are maybe rare?

 

[Youthanasia]

Quote:

Originally Posted by MikeW /img/forum/go_quote.gif i'd like to experiment with other op-amps as well. Though im not willing to cut my EF1 up hehe. It would be nice if there was a single chip op-amp like the OP275 that performed beter then these dual ad743's. From what I can tell there's not been a whole lot of op-amp rolling done by EF1 owners. I don't even know what kind of op-amp it requires or how to get a list of compaitible OP-amps. I think it's a dual channel op-amp, which are maybe rare?

AD743JN is single opamp if I'm not mistaken. How did you manage to get two of those inside the EF1 without cutting

?
:curious:
Care to make a photo?

 

[138177]

Hi guys,

I've just finished burning in my EF1 with the stock RCA cleartops, but the sound is bit brighter and just a tad more analytical than I want, so I've gone ahead and ordered a Mullard CV4003 tube for hopefully a richer sound. It should arrive by the end of the week, and I'll post impressions after that.

 

[somestranger26]

Quote:

Originally Posted by gjergji /img/forum/go_quote.gif I have the OP275, AD797BRZ, BB OPA 627AU, BB OPA 627BP, LM4562NA, Tried audiogd, sun moon and earth. All three gave me hissing, or no sound after a while.. Not sure what was the cause. Talked with audio-gd. Connected earth to GND of EF1... all the same.. Now I'm looking for some new op amps to play with.. Any suggestions?

Same experience with the audio-gd modules for me, except it was a buzzing sound (60hz power hum) and grounded/ungrounded didn't make a difference.

 

[Karl H]

Quote:

Originally Posted by scottyeatcereal /img/forum/go_quote.gif Hi guys, I've just finished burning in my EF1 with the stock RCA cleartops, but the sound is bit brighter and just a tad more analytical than I want, so I've gone ahead and ordered a Mullard CV4003 tube for hopefully a richer sound. It should arrive by the end of the week, and I'll post impressions after that.

I used the clear top for a while. Have moved on to a Brimar CV4003 which I'm really enjoying. A bit creamier than the RCA, and better for it.

Also have a Sylvania and an Arcturus 5963. Haven't spent much time with either, but the Arcturus has a noticeably heavier bottom end. Could be interesting.

Managed to bag a Mullard ECC82 on ebay a couple of days ago for £2.99 - bargain! The chap was selling a few, the others in pairs. They went for over £30, but nobody seemed interested in the single tube. Good for me.

 

[138177]

Quote:

Originally Posted by Karl H /img/forum/go_quote.gif I used the clear top for a while. Have moved on to a Brimar CV4003 which I'm really enjoying. A bit creamier than the RCA, and better for it. Also have a Sylvania and an Arcturus 5963. Haven't spent much time with either, but the Arcturus has a noticeably heavier bottom end. Could be interesting. Managed to bag a Mullard ECC82 on ebay a couple of days ago for £2.99 - bargain! The chap was selling a few, the others in pairs. They went for over £30, but nobody seemed interested in the single tube. Good for me.

Sweet deal! I was deciding between the CV4003 and the ECC82, both of which seem solid but I found more of a consensus behind the CV4003. What do you think of the two compared to one another?

 

[Karl H]

Dunno, hasn't arrived yet. 6 day delivery expectation on 2nd class. Meh...

 

[138177]

Quote:

Originally Posted by Karl H /img/forum/go_quote.gif Dunno, hasn't arrived yet. 6 day delivery expectation on 2nd class. Meh...

ahh yes, the dreaded wait time. good luck then i look forward to your impressions. so far I've just got that RCA cleartop to Mullard CV4003 comparison coming up, but I'll post what i think when it arrives next week.

 

[nttg]

EF1 arrived today and my impression is alright, it doesn't have enough juice for k272 to keep the heavy bass.