http://myweb.tiscali.co.uk/nuukspot/decdun/gainclone.html
That amplifier has been in audiophile service since 2003. That makes it a good baseline reference.
From previous experience, I have to regard LM3875 as a hyper revealing component that is intolerant of minor design variations. That's personal opinion, but there are also thousands of documentations on the subject.
Therefore I want to build his amplifier straight on spec.
Most of the specs are listed on this page http://myweb.tiscali.co.uk/nuukspot/decdun/gainclonesl.html but I'd like to get really, really picky, because I, personally, believe that I would otherwise not hear exactly the results as reported.
So, I'd like to ask for help.
Right away, I'm in trouble. Even if I could find the discontinued transformer, it will do differently (half the inductance ratio) when the primaries are arranged for my 115v wall outlet. Therefore, I'm in need of a "closest match" substitute. If I read correctly, the transformer from the Arcam A60 was used, and then it was replaced by two 36vct (18,0,18) transformers, details unknown except that they were preferred. Any ideas?
That amplifier has been in audiophile service since 2003. That makes it a good baseline reference.
From previous experience, I have to regard LM3875 as a hyper revealing component that is intolerant of minor design variations. That's personal opinion, but there are also thousands of documentations on the subject.
Therefore I want to build his amplifier straight on spec.
Most of the specs are listed on this page http://myweb.tiscali.co.uk/nuukspot/decdun/gainclonesl.html but I'd like to get really, really picky, because I, personally, believe that I would otherwise not hear exactly the results as reported.
So, I'd like to ask for help.
Right away, I'm in trouble. Even if I could find the discontinued transformer, it will do differently (half the inductance ratio) when the primaries are arranged for my 115v wall outlet. Therefore, I'm in need of a "closest match" substitute. If I read correctly, the transformer from the Arcam A60 was used, and then it was replaced by two 36vct (18,0,18) transformers, details unknown except that they were preferred. Any ideas?
Dan, if you haven't twigged yet, factors such as the mains supply, and your listening environment have a much bigger affect on the sound of a chip amp, than the type of cap, resistor, or even power supply.
You must be able to find a 120VA 25v centre-tapped transformer somewhere in the USA. But what have you been using to date? Can't you try something that you already have to get up and running. Then if you are not satisfied, go out and buy another traffo. Life doesn't have to be quite so complex! 😉
You must be able to find a 120VA 25v centre-tapped transformer somewhere in the USA. But what have you been using to date? Can't you try something that you already have to get up and running. Then if you are not satisfied, go out and buy another traffo. Life doesn't have to be quite so complex! 😉
Hi man!! Thank you!!!
I'm so glad you're here because I'd love to hear the very amplifier that you described (hopefully at less cost than the airline ticket). 😉
I do happen to have this transformer: http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=2272065
And I have a pair of these: http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=9288566
Or, should a use a toroid (or two?) for "closest match"?
EDIT: I've got to get some from here anyway http://www.antekinc.com/price1.html, so if one (or two?) of these is more suitable, it would save me some cost to ship in the same box.
Thanks again! 😉
I'm so glad you're here because I'd love to hear the very amplifier that you described (hopefully at less cost than the airline ticket). 😉
I do happen to have this transformer: http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=2272065
And I have a pair of these: http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=9288566
Or, should a use a toroid (or two?) for "closest match"?
EDIT: I've got to get some from here anyway http://www.antekinc.com/price1.html, so if one (or two?) of these is more suitable, it would save me some cost to ship in the same box.
Thanks again! 😉
I apologise if my English isn't that clear! What I am trying to get over to you is that you won't hear the same amp that I built because too many other things affect the sound.
You don't 'hear' an amp. You hear what is coming out of the speakers and how that is affected by the room you are in, and by what is fed into the amp by the previous stage(s).
When you build that basic design, you have a starting point by which to judge other chip amp designs. But it is your starting point, as the one I built was my starting point. There is no universal ideal here! 😉
You don't 'hear' an amp. You hear what is coming out of the speakers and how that is affected by the room you are in, and by what is fed into the amp by the previous stage(s).
When you build that basic design, you have a starting point by which to judge other chip amp designs. But it is your starting point, as the one I built was my starting point. There is no universal ideal here! 😉
danielwritesbac said:
Your first solid-state amplifier, Nuuk's gainclone, the "I got bored" project in between...
Are you trying to beat destroyer X to the Guinness Book of Records for the biggest number of DIY amps?
Nuuk said:
Oh, its me that wasn't clear. But, I would like to know if the amp (the one you use) is dual-mono or not.
pacificblue said:
Sorry that I'm so hyper.
The "I got bored." is an older design that's getting finished up. The solid state project is because I was curious about the many available.
Almost, almost, I said "the many flavors available," but then I remembered our ROHS conversation. 😉
Nuuk's gainclone, I want to hear, because I've never won a fight with LM3875 yet. However, the description on that page is exactly what I like it to do. 😉
The one I use is the one with the Resurrector, and as described in the TNT review. The subject of this thread was dual mono as clearly stated in the article!
Nuuk said:
Sorry man. I was confused by the 1 transformer on the parts list. Now, I remember reading that I was supposed to double-up that list. Oh sorry. I'll go print the article and read several more times (without all that screen scrolling).
P.S. I can't find the transformer VS33L on Maplin. Is that Toriod?
Oh, what a workout! 😉 I think that I've managed to identify all of the components except for. . .
The type, gauge and length of the power supply (to amp) interconnect cable. That's an resistant and inductive power supply component and will make an audio difference if I used something different for establishing a pole. This one is pretty important!
I'd love to know more about that shiny red 2W metal film resistor in series with the input, but probably could make an approximation there if the exact same component can't be found.
The type, gauge and length of the power supply (to amp) interconnect cable. That's an resistant and inductive power supply component and will make an audio difference if I used something different for establishing a pole. This one is pretty important!
I'd love to know more about that shiny red 2W metal film resistor in series with the input, but probably could make an approximation there if the exact same component can't be found.
AndrewT said:
Well, if you read the article enough times, you'll eventually notice the lentils. This seems like material for April. However, yes, indeed, I'm going to go buy lentils. I don't want even the slightest input on the design. In considering it a baseline reference, there must not be a change.
The less changes, the closer match to the reference, and I intend to do a quality job.
As the power supply is much like CRC, I don't find it inappropriate to ask what was used for the inductive resistor at position R in the CRC.
There's mention of 0.6mm solid core wire of un-determined length or the option of 16ga multistrand, but there's no mention of cable length and there's no mention of which was in actual use over the longest time period of the amplifier's audiophile service.
I'm still reading the article over and again to see if I can spot the power supply cable length information.
I'm still reading the article over and again to see if I can spot the power supply cable length information.
danielwritesbac said:
But it's someone else's reference, is it not? Unless you already have an intimate knowledge of Nuuk's amp, what difference does it make if your component-for-component clone ends up being identical to or has some miniscule differences from Nuuk's?
tubesguy said:
Actually, I only need one channel like Nuuk's amplifier. It is for reference, and I wouldn't want to make the reference inaccurate. I want to hear what LM3875 is supposed to sound like, and that one did 3 years audiophile service. Good reference.
Power options can make large differences, and since there's one way to find out, I still need to know the length of the cable from power supply to amplifier enclosure.
An inductive resistor (the power supply interconnect cable) within a CRC supply is a critical component value, especially considering the low capacitance power supply.
danielwritesbac said:
Once again we see Mr. Writesbac not seeing the forest for the trees. You are putting WAY too much emphasis on very, very minor details. Details that you will NOT hear. If you make the cable 20 meters instead of 20cm then MAYBE you would hear a difference.
Follow all good practices and just build it!
Did it? News to me! As far as I knew that particular GC sat on a shelf after I built my second GC.
Small ones in my experience but then I've never spent weeks worrying about the most minute details - I've just got on and built the thing!
Well I must have changed that cable a dozen times and never noticed any difference!
Daniel I honestly feel for you. It can't be easy living in a head like that. May I sincerely recommend that you take up something like meditation or yoga? 😉
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