OP27 Replacement in KG amp?

Garbz · 21st March 2004, 03:31 AM

Hi all

Some of you might have seen my message last week or the week before, i'm in the process of starting a Gilmore Class-A Dynmaic Heapdhone ampifier.

I've come across a hitch with the OP27. As far as I understand this chip feeds the output into the DC offset with a little voltage gain so the amp runs in class A??? Is that right i'm not sure, i don't normally work with discreet amps.

The problem is i'm on a really low budget, and find the OP27 and it's high retail price a bit expensive. Also i have no easy supply of opamps so i'll need to order from texas instruments, so add shipping costs and i definatly can't afford it.

Texas Instruments offers samples of most of their chips (inc Burr Brown chips), and the OP27 is not one of thoes chips.

Is there a substitute i can use instead of the OP27, which is availuable from Texas Instruments, or is cheaper, and doesn't compromise sound quality? It doesn't matter if they don't have the same pinout i can easily modify the design.

greyhorse · 21st March 2004, 04:22 AM

I don't mean to sound discouraging, but most of the questions that could possibly be asked regarding this amplifier have already been asked and answered on the Headwize forum.
I know it's hard using the search function when you don't know for sure that your question's been asked, but there really is a lot of information there.

http://headwize2.powerpill.org/ubb/s...gilmore;opamp;

http://headwize2.powerpill.org/ubb/s...gilmore;opamp;

Mad_K · 21st March 2004, 05:28 AM

OPA27GP

peranders · 21st March 2004, 07:01 AM

Garbz, the opamp is used as DC-servo and virtually any good audio opamp will fit because the application isn't very critical. Just pick an opamp and I can tell you if it's good or not.

tbla · 21st March 2004, 08:41 AM

per,
i have a cdplayer with op27 as servoopams - would the opa627 perform better.....?

Garbz · 21st March 2004, 10:13 AM

sorry i did try searching op27 replacement in both forums but came up with nadda. Thanks for the links.

I've got opa134, opa627, opa637, on hand.
I can easily get TL071, LF351, LM301, LM308, lm747, ne5534n, ne5534an.

I'm gonna use the opa134 (cheap = win)

Also mad_k don't know where u find the Gp but i can only see the GB, and no samples availuable and 10usd + god knows for delivery.

was ist los? · 22nd March 2004, 12:38 AM

I've built this amp. I use the OP27 in it, but others have used the OPA227. Those are the two most commonly used in the servo. The OPA132 you have will work. I say don't waste an OPA627 in there as it won't impact sound at all.

Garbz · 22nd March 2004, 02:11 AM

ok thanks a lot everyone.

21st March 2004, 03:31 AM	#1
Garbz diyAudio Member Join Date: Dec 2003 Location: Brisbane	OP27 Replacement in KG amp? Hi all Some of you might have seen my message last week or the week before, i'm in the process of starting a Gilmore Class-A Dynmaic Heapdhone ampifier. I've come across a hitch with the OP27. As far as I understand this chip feeds the output into the DC offset with a little voltage gain so the amp runs in class A??? Is that right i'm not sure, i don't normally work with discreet amps. The problem is i'm on a really low budget, and find the OP27 and it's high retail price a bit expensive. Also i have no easy supply of opamps so i'll need to order from texas instruments, so add shipping costs and i definatly can't afford it. Texas Instruments offers samples of most of their chips (inc Burr Brown chips), and the OP27 is not one of thoes chips. Is there a substitute i can use instead of the OP27, which is availuable from Texas Instruments, or is cheaper, and doesn't compromise sound quality? It doesn't matter if they don't have the same pinout i can easily modify the design.

21st March 2004, 05:28 AM	#3
Mad_K diyAudio Member Join Date: Sep 2002 Location: Norway	OPA27GP __________________ Mads K

21st March 2004, 07:01 AM	#4
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Garbz, the opamp is used as DC-servo and virtually any good audio opamp will fit because the application isn't very critical. Just pick an opamp and I can tell you if it's good or not. __________________ /Per-Anders (my first name) or P-A as my friends call me

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21st March 2004, 04:22 AM	#2
greyhorse diyAudio Member Join Date: Feb 2002 Location: Ontario	I don't mean to sound discouraging, but most of the questions that could possibly be asked regarding this amplifier have already been asked and answered on the Headwize forum. I know it's hard using the search function when you don't know for sure that your question's been asked, but there really is a lot of information there. http://headwize2.powerpill.org/ubb/s...gilmore;opamp; http://headwize2.powerpill.org/ubb/s...gilmore;opamp;

21st March 2004, 08:41 AM	#5
tbla diyAudio Member Join Date: Jul 2002 Location: denmark	per, i have a cdplayer with op27 as servoopams - would the opa627 perform better.....?

21st March 2004, 10:13 AM	#6
Garbz diyAudio Member Join Date: Dec 2003 Location: Brisbane	sorry i did try searching op27 replacement in both forums but came up with nadda. Thanks for the links. I've got opa134, opa627, opa637, on hand. I can easily get TL071, LF351, LM301, LM308, lm747, ne5534n, ne5534an. I'm gonna use the opa134 (cheap = win) Also mad_k don't know where u find the Gp but i can only see the GB, and no samples availuable and 10usd + god knows for delivery.

22nd March 2004, 12:38 AM	#7
was ist los? diyAudio Member Join Date: Sep 2003	I've built this amp. I use the OP27 in it, but others have used the OPA227. Those are the two most commonly used in the servo. The OPA132 you have will work. I say don't waste an OPA627 in there as it won't impact sound at all.

22nd March 2004, 02:11 AM	#8
Garbz diyAudio Member Join Date: Dec 2003 Location: Brisbane	ok thanks a lot everyone.

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