Hello all,
I'm going to make MickF's minimalist LM3886 amp: Three-resistor LM3886 chipamp
And make a no capacitor power supply.
I have 4 bridge rectifiers and have found 10 MUR860 diodes.
I wondered if it would be worth buying 6 more diodes or just use the bridges?
Cheers
I'm going to make MickF's minimalist LM3886 amp: Three-resistor LM3886 chipamp
And make a no capacitor power supply.
I have 4 bridge rectifiers and have found 10 MUR860 diodes.
I wondered if it would be worth buying 6 more diodes or just use the bridges?
Cheers
Hi Jem, I got an email that you had made post 801. I made many gainclones years ago, several LM3886 amps and some nice LM3875 monoblocks sit gathering dust! I wondered if you were aware of a site called Decibel Dungeon run by Nick Whetstone (TNT reviewer) There is a lot of good stuff on there. One thing I tried was the T-Network for the feedback. As he says it does sound more detailed, not necessarily better, Where did you get your MUR860's?
Link to DD site Building a Gainclone chip amp with T-network feedback network.
Link to DD site Building a Gainclone chip amp with T-network feedback network.
Hello Puffin,
Many thanks for your message and for the links, I did know of Nick's site and have modified a Philips CD723 using his instructions.
I have also written to Mick_F asking about his two resistor amp: Mick Feuerbacher Audio Projects I prefer this and will build it.
The 'MUR860's' have U860 on them, but I will use a pair of bridge rectifiers, these plus two transformers are already in a box I'd made for an LM3875 GC which sounded rather weedy.
Cheers
Many thanks for your message and for the links, I did know of Nick's site and have modified a Philips CD723 using his instructions.
I have also written to Mick_F asking about his two resistor amp: Mick Feuerbacher Audio Projects I prefer this and will build it.
The 'MUR860's' have U860 on them, but I will use a pair of bridge rectifiers, these plus two transformers are already in a box I'd made for an LM3875 GC which sounded rather weedy.
Cheers
Hello everyone!
I have a 2x30V 500VA toroidal laying around. Now, as I've understood it, 30VAC will give 42VDC once rectified, which would give a total supply voltage of 84VDC (absolute values of + and - rails). Would this be too much for the LM3886? Asking since the datasheet states 84V max and worried about the supply voltage ending up slightly higher than 42V, per rail. Would regulating the supply be a better alternative?
My plan is to build a separate PSU, in order to use it with two different amplifiers in the future (not simultaneously), one of which will require a large transformer.
Thanks in advance!
Regards, Hugo
I have a 2x30V 500VA toroidal laying around. Now, as I've understood it, 30VAC will give 42VDC once rectified, which would give a total supply voltage of 84VDC (absolute values of + and - rails). Would this be too much for the LM3886? Asking since the datasheet states 84V max and worried about the supply voltage ending up slightly higher than 42V, per rail. Would regulating the supply be a better alternative?
My plan is to build a separate PSU, in order to use it with two different amplifiers in the future (not simultaneously), one of which will require a large transformer.
Thanks in advance!
Regards, Hugo
Hi Hugo, I made 2 LM3875 Monoblocks with 30vac transformers. I made some regulators from the information in the link below as unregulated would be subject to more voltage due to mains supply rise.
Building an LM3886 Gainclone chip amp with a regulated power supply (PSU).
These amps sound great and I have never had any problem with them.
Building an LM3886 Gainclone chip amp with a regulated power supply (PSU).
These amps sound great and I have never had any problem with them.
Thanks for the advice Puffin!
I have a dual LT1083 board, and another on it's way, so I will try using these! Seemed like a simpler and more robust solution running without regulators, hence my question.
Btw, noticed on the DigiKey page for the LM338 regulator it says: Voltage - input (Max): 40V. How does this work given that 30VAC -> 42VDC? Or is the Voltage - input (Max) the maximum voltage drop the regulator can handle?
Regards, Hugo
I have a dual LT1083 board, and another on it's way, so I will try using these! Seemed like a simpler and more robust solution running without regulators, hence my question.
Btw, noticed on the DigiKey page for the LM338 regulator it says: Voltage - input (Max): 40V. How does this work given that 30VAC -> 42VDC? Or is the Voltage - input (Max) the maximum voltage drop the regulator can handle?
Regards, Hugo
Unpopulated boards
Hi!
This might just be a case of laziness where the answer is buried somewhere in this thread... but here goes...
I'm building a neat little lm1875-amp and was wondering if anyone knows any suitable (and good) unpopulated boards from ebay or other sources?
I,m gonna use it with a 100 va dual 21v toroidal, LQA16T300 rectifiers that I have over, and the filter caps, bleeders etc. I'll buy as I go along. I find a lot of them from China, but I don't really have the knowledge to say if they look good or messy...
(Of course they can be kits as long as they aren't assembled.)
Hi!
This might just be a case of laziness where the answer is buried somewhere in this thread... but here goes...
I'm building a neat little lm1875-amp and was wondering if anyone knows any suitable (and good) unpopulated boards from ebay or other sources?
I,m gonna use it with a 100 va dual 21v toroidal, LQA16T300 rectifiers that I have over, and the filter caps, bleeders etc. I'll buy as I go along. I find a lot of them from China, but I don't really have the knowledge to say if they look good or messy...
(Of course they can be kits as long as they aren't assembled.)
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Hello Vilding,
With great respect you do not need a board for this amplifier the components are so few that they can be joined to each other very neatly. The whole ethos of the ChipAmp is to have the shortest paths one can achieve.
Please see my signature link below for some pics, do have a go it's surprisingly easy.
Cheers
With great respect you do not need a board for this amplifier the components are so few that they can be joined to each other very neatly. The whole ethos of the ChipAmp is to have the shortest paths one can achieve.
Please see my signature link below for some pics, do have a go it's surprisingly easy.
Cheers
Nice! Those horns look amazing as well! I've been wanting to hear a pair for some time.
I kinda like the no-filter-cap-approach. How does that change the value of the feedback caps?
I got some Chinese amp-board kits from Ebay that I think I'll stick to, even though I'll swap out most of the parts for guaranteed legit ones as both boards and original parts are quite inexpensive.
I'm new to this thing but having a blast with it so far.
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Hello Vilding,
The feedback is just a short length of wire no caps involved. I found that with a large capacitor power supply the sound is big fat and round. With just Transformers/Rectifiers and capacitors connected closely to the chip the sound is very analytical. Another reason for P2P is being able to change things, I started with 1,000 uf and changed that to 2,200 uf with a 100 nf across it. I am using 4 Ohm speakers though.
There isn't just one answer to these things, if you do buy a PCB may I suggest that you use some Veropins so that you can change stuff easily.
Cheers
The feedback is just a short length of wire no caps involved. I found that with a large capacitor power supply the sound is big fat and round. With just Transformers/Rectifiers and capacitors connected closely to the chip the sound is very analytical. Another reason for P2P is being able to change things, I started with 1,000 uf and changed that to 2,200 uf with a 100 nf across it. I am using 4 Ohm speakers though.
There isn't just one answer to these things, if you do buy a PCB may I suggest that you use some Veropins so that you can change stuff easily.
Cheers
Hello Vilding,
Goodness gracious, I'm no expert at circuits or desgning such merely a listener who know that the components look like and how to convert a circuit digram into a working item.
The schematic looks like one for an opamp, but, who am I to say yay or nay whether it will work. I would say that the 220 uf caps need to be at least 1,000 uf
The original GainCard pic, description and circuit here: Mick Feuerbacher Audio Projects Sakura Systems are still selling them @$5,000+
Cheers
Goodness gracious, I'm no expert at circuits or desgning such merely a listener who know that the components look like and how to convert a circuit digram into a working item.
The schematic looks like one for an opamp, but, who am I to say yay or nay whether it will work. I would say that the 220 uf caps need to be at least 1,000 uf
The original GainCard pic, description and circuit here: Mick Feuerbacher Audio Projects Sakura Systems are still selling them @$5,000+
Cheers
Hello Vilding,
Most threads on here can leave the reader somewhat confused, as I am with making a JLH 1969, so I've gone back to the source.
My GC source was Building a basic inverted Gainclone chip amp using hard-wiring this is a 'proper GainClone and it will serve you well for many years, I can promise that sincerely.
Cheers
Most threads on here can leave the reader somewhat confused, as I am with making a JLH 1969, so I've gone back to the source.
My GC source was Building a basic inverted Gainclone chip amp using hard-wiring this is a 'proper GainClone and it will serve you well for many years, I can promise that sincerely.
Cheers
Yeah they kinda put you in a loop...
But a lot of interesting reading and very nice projects! I am also building a Folsom EC7293 (waiting for Covid-delayed tranies) and I think I'm gonna finish that and then build one of those minimal dual mono ones as a desk top amp. There is something alluring with that minimal approach!
With this one (lm1875) I'm gonna keep it cheap and split a 48v power brick with "faux" ground/reference. It's gonna go in my parents fishing/sauna and wine cabin, so it's not gonna be subjected to an extreme amount of critical listening. If i like it I might build a proper power supply for it in the future.
Thank you for the advice and great links!
I have a question... I’m using a pair of Chipamp.com power supplies to feed a pair of 3886 amp boards. The required rectifier diodes are MUR860 but I couldn’t find any at the time of ordering so I bought some MUR840 instead. I know I should have asked beforehand but I got caught up in the moment and, well, now I have them. Is it safe and alright to use them in place of the required units?
Thanks
Thanks