Hi,
Here.
http://sound.westhost.com/project56.htm
I very much do not ENDORSE the vast majority of the material on the noted website, nor do I agree with Rod Elliots views the least bit, but the above article is the only readily available one that covers this.
Sayonara
Here.
http://sound.westhost.com/project56.htm
I very much do not ENDORSE the vast majority of the material on the noted website, nor do I agree with Rod Elliots views the least bit, but the above article is the only readily available one that covers this.
Sayonara
dhaen said:Don' t do anything with the primary.
Wind some turns through the middle of the "donut" and out.
Maybe 10 turns to try. This is a "new" secondary. Then take one of the original secondary wires, and connect this new "winding" in series with it. Measure the new voltage on that new combined secondary. If it's gone down:good. If it's gone up: reverse the new winding's connections.
If you have 2 secondarys, youll need 2 sub-secondarys.
Cheers,
great thanks, i am guessing about 15 turns will do it? (i want it around 25v, it is 30v now)
also, would there be any benifit from using a better powersupply (regulators, ect ) or would the larger ammount of componets result is cheaper componets used which would make the sound worse?
Fez,
The number of turns required depends on the actual transformer.
I normally use the same hookup wire as I use for wiring. But if you were to wind a lot of turns, you should use a suitable enamelled copper wire. You can buy it from Maplin, quite close to you.
BTW I live in Leighton Buzzard
Cheers,
The number of turns required depends on the actual transformer.
I normally use the same hookup wire as I use for wiring. But if you were to wind a lot of turns, you should use a suitable enamelled copper wire. You can buy it from Maplin, quite close to you.
BTW I live in Leighton Buzzard
Cheers,
misbehaving clone
i have recently finished a gainclone (using opa549), and the sound was fantastic. checking it with a multimeter though, i get 88mV on one channel (which sound right), and 5mV on the other (which seems a little distressing). what could be causing this, and how can it be fixed? any help would be most appreciated as this is my first amp and i still have a lot to learn.
thanks,
Hamish
i have recently finished a gainclone (using opa549), and the sound was fantastic. checking it with a multimeter though, i get 88mV on one channel (which sound right), and 5mV on the other (which seems a little distressing). what could be causing this, and how can it be fixed? any help would be most appreciated as this is my first amp and i still have a lot to learn.
thanks,
Hamish
Sounds stupid sorry but this phenomenon is quite new for me...
Is that normal that we get some mV on the output when there's no signal ? Is that what you call DC offset ?
When connecting a speaker on an output with a little offset, is the cone supposed to bit a little stiffer than when the amp is shut off ?
How much "offset" is tolerable ?
tnx
Pan said:
In addition to Thorsten's (oops! Kwei's) reference, here are some more from Malcolm Hawksford (J12 and after).
http://www.essex.ac.uk/ese/research/audio_lab/malcolms_publications.html
No text, just titles to his numerous (!) JAES and AES articles. But with a little digging you might be able to get a reprint of the most interesting.
You could even post them here.
Steve
I just finshed one channel, based on the Throsten schematic.
Loudspeakers about 89db sensitivity, 24V secondaries on the trannie.
BUT
It really hasn't too much power. I have changed the input pot to 50K and that's already better. It simply doesn't seem to be 50w max output power.
What can I do?
Marc
Loudspeakers about 89db sensitivity, 24V secondaries on the trannie.
BUT
It really hasn't too much power. I have changed the input pot to 50K and that's already better. It simply doesn't seem to be 50w max output power.
What can I do?
Marc
protos said:
I'm surprised that there hasn't been much discussion of this. Another common solution would be to just remove the capacitor to ground on the noninverting input and use it as an input through another 10K resistor. This is not ideal from a CMRR standpoint due to the unequal input impedances, but there are always compromises and this might be superior to adding an active differential reciever. (less components in the signal path)
Rod Elliot also long ago offered some fudges that help (a little) to ameliorate the problems of this setup. I think this could be worth experimenting with, and I certainly plan to. I guess the primary disadvantage is that we are no longer using only the noninverting input, which could change the sound.
http://sound.westhost.com/project51.htm
dhaen said:Fez,
The number of turns required depends on the actual transformer.
I normally use the same hookup wire as I use for wiring. But if you were to wind a lot of turns, you should use a suitable enamelled copper wire. You can buy it from Maplin, quite close to you.
BTW I live in Leighton Buzzard
Cheers,
i was thinking the same thing, however for saving cost i will try 30A solid core pvc coated mains wire first, and if it dosn't work well, or at all then i will run dosn to maplins and get some wire.
Everything seems to be working well now although I have a few questions.
I have a stereo gainclone with PS built into a chassis not much bigger than your average car radio. Of course the trafo is only 120VA for both channels!
The buzz I was getting turned out to be some kind of ground loop and everything was quiet when I connected star ground to the chassis.I don't know why this worked because inputs ,outputs and circuit were isolated from the chassis so ther shouldn't have been internal to chassis ground loops.Thats mystery number one.
Secondly the dc offset of around 100mv drooped to around 20mv when I snapped in an XLR to RCA adaptor on the XLR type inputs that I used instead of the normal RCA with a view to trying balanced connections in the future. I don't understand this because I am only using pins 1 and 2 any way with 3 unconnected.The XLR adaptor just shorts pins 1 and 3(unused) so it shouldn't have had any effect on the circuit.
This little gainclone was driven by a Balanced Zen Line Stage using unbalanced connections.It was dwarfed by the two Aleph 5 monoblocks which are the resident amps.
As to the sound I have to say that it is embarassing!
After having spent ten times as much dineros and slaved away ten times more hours on the Alephs to have something so cheap and tiny giving them stiff competition makes one want to cry. I mean even my pre amp has a bigger PS than the gainclone.
There was no lack of power driving my 4ohm 90db Zingali speakers to quite loud levels although it did run out of steam before my Alephs do. I calculate that I listen at about 3 to 10 watts and these levels are more than loud enough. The gainclone was quite happy driving at these levels even with the diminutive trafo.
First impressions were of very good 3D sound staging with an explicit but not tiring mid-range and extended and smooth top end. I can understand why a tube lover would like this amp because it it did have a natural midrange , a bit forward but without sounding harsh.Sibilants , which is one thing that annoys me a lot were very well controled.The amp was very well controled and remained unflustered even on complex passages where I had expected it harden a little bit. The bass did not go as deep as the Alephs but on the other hand was very well controled and tuneful. The general presentation was very musical without sounding hi-fi ish. Of course these are still first impressions in the first couple of hours. This morning I had another listen and seemed that the presentation was lighter and brighter which I was not enthusiastic about.
Anyway more serious listening will be done on the weekend and perhaps a match-up against the Alephs.
I would appreciate any technical or other comments.
I have a stereo gainclone with PS built into a chassis not much bigger than your average car radio. Of course the trafo is only 120VA for both channels!
The buzz I was getting turned out to be some kind of ground loop and everything was quiet when I connected star ground to the chassis.I don't know why this worked because inputs ,outputs and circuit were isolated from the chassis so ther shouldn't have been internal to chassis ground loops.Thats mystery number one.
Secondly the dc offset of around 100mv drooped to around 20mv when I snapped in an XLR to RCA adaptor on the XLR type inputs that I used instead of the normal RCA with a view to trying balanced connections in the future. I don't understand this because I am only using pins 1 and 2 any way with 3 unconnected.The XLR adaptor just shorts pins 1 and 3(unused) so it shouldn't have had any effect on the circuit.
This little gainclone was driven by a Balanced Zen Line Stage using unbalanced connections.It was dwarfed by the two Aleph 5 monoblocks which are the resident amps.
As to the sound I have to say that it is embarassing!
After having spent ten times as much dineros and slaved away ten times more hours on the Alephs to have something so cheap and tiny giving them stiff competition makes one want to cry. I mean even my pre amp has a bigger PS than the gainclone.
There was no lack of power driving my 4ohm 90db Zingali speakers to quite loud levels although it did run out of steam before my Alephs do. I calculate that I listen at about 3 to 10 watts and these levels are more than loud enough. The gainclone was quite happy driving at these levels even with the diminutive trafo.
First impressions were of very good 3D sound staging with an explicit but not tiring mid-range and extended and smooth top end. I can understand why a tube lover would like this amp because it it did have a natural midrange , a bit forward but without sounding harsh.Sibilants , which is one thing that annoys me a lot were very well controled.The amp was very well controled and remained unflustered even on complex passages where I had expected it harden a little bit. The bass did not go as deep as the Alephs but on the other hand was very well controled and tuneful. The general presentation was very musical without sounding hi-fi ish. Of course these are still first impressions in the first couple of hours. This morning I had another listen and seemed that the presentation was lighter and brighter which I was not enthusiastic about.
Anyway more serious listening will be done on the weekend and perhaps a match-up against the Alephs.
I would appreciate any technical or other comments.
I have build the Thor amplifier with LM3886 and found out that it
has the mute function that is by default on (how stupid!!!!!)
So I don't get anything on output. I'am reading the datasheet now and I don't understand how to calculate Rm.
My supply voltage is +-18V (for now...just a test module, until
I buy a suitable transformer).
Can anybody help me calculate value of Rm?
tnx,
mario
has the mute function that is by default on (how stupid!!!!!)
So I don't get anything on output. I'am reading the datasheet now and I don't understand how to calculate Rm.
My supply voltage is +-18V (for now...just a test module, until
I buy a suitable transformer).
Can anybody help me calculate value of Rm?
tnx,
mario
Peter - ? about GC housing
Hi Peter!
How hot does your Gainclone get? (the silver one) - 'I have some Al plates at home - 6mm - that could be used for front and rear and 4mm - for side, top and bottom - the complete dimensions of the housing would be something like (255x80x170) WxHxL - do you think that would be enough to cool it down (stereo) or should I use aditional heatsink?? I mean - I will do 2x25W version.
Btw - what is thickness of your GC and what about the housing dimensions?!?
Thanks in advance
LP
Stabist
Hi Peter!
How hot does your Gainclone get? (the silver one) - 'I have some Al plates at home - 6mm - that could be used for front and rear and 4mm - for side, top and bottom - the complete dimensions of the housing would be something like (255x80x170) WxHxL - do you think that would be enough to cool it down (stereo) or should I use aditional heatsink?? I mean - I will do 2x25W version.
Btw - what is thickness of your GC and what about the housing dimensions?!?
Thanks in advance
LP
Stabist
The main reason to build myself a GC (apart from curiosity does it really sound so good) - is to use it as a PC (that's not final decision yet) and mainly as a "night" amp - to have some music on during I sleep - I like that a lot - but since now A5 will be the heart of the system - I don't think that is a good choice for that - the electric bill could get a bit to high ...
And there is another point - as said - if used for PC - then I will have to make some nice litle speakers - and that could became my "portable sistem" - e.g. in a pair with portable CD - it can be quite handy when you go to holidays and so ...
Hmm - any sugestion for small and economical DiY speakers - very very welcomed ...
And there is another point - as said - if used for PC - then I will have to make some nice litle speakers - and that could became my "portable sistem" - e.g. in a pair with portable CD - it can be quite handy when you go to holidays and so ...
Hmm - any sugestion for small and economical DiY speakers - very very welcomed ...
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