Re: Re: Now to find somewhere in the UK to buy...
You need an account with RS. They no longer 'retail'. I'll be ordering early next week I should think.
I'll have to telephone Farnell again then about that direct ship thing . Minimum order is £20 they told me this week. Free post.
Paypal should be fine. We'll talk about that via e-mail 🙂
SimontY said:
You need an account with RS. They no longer 'retail'. I'll be ordering early next week I should think.
I'll have to telephone Farnell again then about that direct ship thing . Minimum order is £20 they told me this week. Free post.
Paypal should be fine. We'll talk about that via e-mail 🙂
Now to find somewhere in the UK to buy...
I believe this is due to them coming from Newark in one, in the USA.
When I tried to buy from 'Newark in One' they wouldn't supply to the UK for orders less than $200 I think it was. Maybe there is a special arrangement when Farnell (also 'in One') are out of stock of an item.
Per my call to them just now, the LM6171 are in stock in Farnell UK, and there are no other charges except VAT for orders over £20.
SimontY said:
I believe this is due to them coming from Newark in one, in the USA.
When I tried to buy from 'Newark in One' they wouldn't supply to the UK for orders less than $200 I think it was. Maybe there is a special arrangement when Farnell (also 'in One') are out of stock of an item.
Per my call to them just now, the LM6171 are in stock in Farnell UK, and there are no other charges except VAT for orders over £20.
Rcd-1072
A friend of mine brought me his Rotel CDP yesterday. I removed the stock BB OPA2277 amps and installed some sockets we performed subsequent listening tests with some of the op-amps we had on hand.
The results were rather typical; I preferred the more melodic sweeter sound of the AD823 where my friend preferred the greater dynamics of the LM6172. I rather like the OPA2277s, and it's certainly much better then the OPA2604s Rotel had been using in their CDPs but the previously mentioned op-amps still did provide some improvement.
My freind also wants me to replace some the 1N400x diodes with ON semiconductor MUR types.
A friend of mine brought me his Rotel CDP yesterday. I removed the stock BB OPA2277 amps and installed some sockets we performed subsequent listening tests with some of the op-amps we had on hand.
The results were rather typical; I preferred the more melodic sweeter sound of the AD823 where my friend preferred the greater dynamics of the LM6172. I rather like the OPA2277s, and it's certainly much better then the OPA2604s Rotel had been using in their CDPs but the previously mentioned op-amps still did provide some improvement.
My freind also wants me to replace some the 1N400x diodes with ON semiconductor MUR types.
What about digi-key? They have stocked every Analog, National, and Burr-Brown opamp (and chipamp) that I have ever looked for. And they stock the Vector pad cutting tools too, but not cheap! They have dedicated websites for 17 countries and everyone else can order from the US site. The LM6172 is UK£2.04.
macboy said:
Wow, I had no idea this existed!
UK web address: http://uk.digikey.com/
Great suggestion, I'll check this out in due course.
Cheers
The problem with digikey is that they add £10 to orders under £75.
Plus shipping and VAT. But I haven't found any details on these from the webiste. The phone numbers are all USA.
So it's not so cheap really, for UK anyway.
The Farnell price for the LM6171BIN single OpApms is the same as the Digikey price. Only there's no handling or shipping to add.
Plus shipping and VAT. But I haven't found any details on these from the webiste. The phone numbers are all USA.
So it's not so cheap really, for UK anyway.
The Farnell price for the LM6171BIN single OpApms is the same as the Digikey price. Only there's no handling or shipping to add.
Ouch! Digi-key in Canada has a modest C$32.50 minimum, with only a C$6.50 surcharge if the order is less than that.
A better version of a great op-amp!
Today I had a chance to compare an AD823AN to a AD823ANZ. The ANZ version is superior; sounding a bit more coherent.😎
Also, yesterday I recieved my BrownDog single-to-dual adaptors and have soldered in my OPA627s and 637s. My initial impression of the 637s is very positive. I'll report my 2 cents after I try them both in some different applications.
Today I had a chance to compare an AD823AN to a AD823ANZ. The ANZ version is superior; sounding a bit more coherent.😎
Also, yesterday I recieved my BrownDog single-to-dual adaptors and have soldered in my OPA627s and 637s. My initial impression of the 637s is very positive. I'll report my 2 cents after I try them both in some different applications.
Re: A better version of a great op-amp!
The 637 is an old love of mine😀, but it should not be used with adapters...
For a quick test yes, but for the best preformance no.
Gaucho said:
The 637 is an old love of mine😀, but it should not be used with adapters...
For a quick test yes, but for the best preformance no.
Re: Re: A better version of a great op-amp!
Agreed, the use of adaptors is not the best.
I use the adaptors only because of the need to retrofit commercial gear where dual op-amps were originally used. Perhaps ideally dual op-amps should not be used at all. I would like to mention that the use of single-to-dual adaptors at least provides the opportunity to utilize seperate decoupling for each of the op-amp circuits, something that is obviously not a possibility with a true dual.
carlosfm said:
Agreed, the use of adaptors is not the best.
I use the adaptors only because of the need to retrofit commercial gear where dual op-amps were originally used. Perhaps ideally dual op-amps should not be used at all. I would like to mention that the use of single-to-dual adaptors at least provides the opportunity to utilize seperate decoupling for each of the op-amp circuits, something that is obviously not a possibility with a true dual.
Since the Carlos-mod for my OPA627A was so succersfull I'm thinking of doing the same for the two (4) OPA2604's in the outputstage of my CDP990. Can I just put 8 resistors of 8k between the negative rails and the output's or is this not gonna work?
GerardA said:
I've tried it with a number of dual op-amps and never had any problems. Some op-amps do respond better to this then others.
I strongly suggest you try some other op-amps in place of the 2604s IMHO they are rather ugly sounding. The LM6172 works well with as little as 1.5mA of bias but for best results don't try to drive to low of an impedance.
Gaucho said:
Gaucho,
I'm a fan of that OA too...
If 1.5 mA is the low limit, what nominal bias current do you fancy for the LM6172N ?
Also, what would you consider 'too low' for a load impedance ?
Regards,
LarryO
lgo51 said:
Larry, with the 6172 I have tried 1.5mA, 2mA and 7.5mA and all values gave a good result
As for load impedance it really depends on a number of factors; like how much bias you are using, how much voltage you are trying to swing and if you are resistor biasing or active biasing. A couple of mA is usually adequate. It's best try a number of values using your ears to guide you.
Gaucho said:
I'm assuming i should calculate the current at idle (0v RMS output) against the -Vs... yes? If not, a spot of help would be useful.
I've seen 'constant current' diodes mentioned for this purpose but have no experience with them. Can you suggest a part # to get me started? Are their any noise considerations with their use, like is true for Zeners? If so, is the simple resistor a better alternative?
Thanks for the assist,
LarryO
Here is a good adjustable current source:
national semi
I have used it a couple of times. 🙂 With opa627/637 and AD8610.
national semi
I have used it a couple of times. 🙂 With opa627/637 and AD8610.
lgo51 said:
For a given idle current an active CS will give you more voltage swing and a higher PSRR. As long as the supply rails are half a$s clean I like resistor biasing. I replaced the CCS source in the front-end of my Alephs with a resistor, the sound improved but (predictable) I got some PS noise at the output. The 2N4304 is what I've seen used in the El cheapo phono stage. The use of the 2N4304 was likely lifted/inspired from the Linear Technology's LT1115 datasheet.
Yep thats how it's done, just good ol' Ohm's law. 🙂
Edit: It doesn't seem possible hyperlink direct to PDFs, the link to the datasheet can found here:
LT1115
Why these LT OpAmps are......
.......never being discussed over here?? 😕
Eg when I look at the Datasheets (well, I know, they don't tell the complete truth) of LT1363/64/65, they should perform quite well.
The most important points are, that
-they don't have extreme high open loop gain as other opamps, which is rather positive than negative for audio.
-they have (therefore) almost flat open loop gain (which results in constant loop gain) over the audio band
-they have pretty high output current capability(50mA)
-loads at output down to 150 Ohms are specified
-capacitive loads (cables) can be driven
There are others like the high output current LT1210, LT1794/95 devices, the LT1028, LT1115 which seem to be quite good performers.
Could anyone enlighten me?
Ciao, Tino
.......never being discussed over here?? 😕
Eg when I look at the Datasheets (well, I know, they don't tell the complete truth) of LT1363/64/65, they should perform quite well.
The most important points are, that
-they don't have extreme high open loop gain as other opamps, which is rather positive than negative for audio.
-they have (therefore) almost flat open loop gain (which results in constant loop gain) over the audio band
-they have pretty high output current capability(50mA)
-loads at output down to 150 Ohms are specified
-capacitive loads (cables) can be driven
There are others like the high output current LT1210, LT1794/95 devices, the LT1028, LT1115 which seem to be quite good performers.
Could anyone enlighten me?
Ciao, Tino
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