A little update on my Gainclone story:
I bought today a pair of Wharfedale MFM5 - proper sized, bass-vented, 3-way floorstanders.
Obviously, I hooked them instantly to my GC to see what happens. And the result was... fantastic, actually
First, they have bass-reflex, so I thought to myself, that most likely they have better efficiency than close-cased Missions. So I thought I might push the amp just a bit harder than the low-to-moderate volume. The sound was alright, so I pushed more... and more... And I ended up with the 125W speaker almost spitting its cones out while pumping incredible sound! The radiator did get hot, but I haven't noticed any impact on sound.
So I went on to check if that singular bass-related sound fainting would occur on these speakers too.
I set up the same ridiculous +12dB boost at 60Hz in Winamp, but forgot to lower the "preamp" bar, so the sound got completely distorted. I lowered "preamp" all the way to -12dB, turned up the volume and... clean, balanced sound in mids and trebles + wildly THUMPING bass.
Apparently, the cause of the problem was simply a weak sound card. Or rather GC's input resistance was too low for it - which comes down to the same.
In my previous tests I was lowering "preamp" bar, but not quite by as much as -12dB. So I reckon the sound was getting messed up simply due to card's output amp being unable to provide enough current.
I feel quite stupid now, because what I thought to be amplifier's fault, turned out to be just inefficient speakers together with poor source
Anyway - Gainclone IS the best thing since sliced bread ;D I've heard better amps, obviously, but their price was light years away from the 57$ I paid for the kit!
I bought today a pair of Wharfedale MFM5 - proper sized, bass-vented, 3-way floorstanders.
Obviously, I hooked them instantly to my GC to see what happens. And the result was... fantastic, actually
First, they have bass-reflex, so I thought to myself, that most likely they have better efficiency than close-cased Missions. So I thought I might push the amp just a bit harder than the low-to-moderate volume. The sound was alright, so I pushed more... and more... And I ended up with the 125W speaker almost spitting its cones out while pumping incredible sound! The radiator did get hot, but I haven't noticed any impact on sound.
So I went on to check if that singular bass-related sound fainting would occur on these speakers too.
I set up the same ridiculous +12dB boost at 60Hz in Winamp, but forgot to lower the "preamp" bar, so the sound got completely distorted. I lowered "preamp" all the way to -12dB, turned up the volume and... clean, balanced sound in mids and trebles + wildly THUMPING bass.
Apparently, the cause of the problem was simply a weak sound card. Or rather GC's input resistance was too low for it - which comes down to the same.
In my previous tests I was lowering "preamp" bar, but not quite by as much as -12dB. So I reckon the sound was getting messed up simply due to card's output amp being unable to provide enough current.
I feel quite stupid now, because what I thought to be amplifier's fault, turned out to be just inefficient speakers together with poor source
Anyway - Gainclone IS the best thing since sliced bread ;D I've heard better amps, obviously, but their price was light years away from the 57$ I paid for the kit!
Too bad I was out for the weekend. The soundcard was my first thought while catching up on the thread.
Time and time again people blame weak bass on lack of capacitance. I'm not going to suggest that more capacitance can't be a good thing. I built one of the audiosector kits, and it sounded just great with the small cap at the rectifier, and 1500uF per rail at the amps.
My new amp has 68000uF per rail. Supply ripple is around 12mV when playing a 20Hz sine wave at high volume.
I don't think I could really tell the difference between them.
With a good PSRR, I think the main difference you're going to see is earlier clipping, and probably some modulation at the line frequency. Obviously that's bad, but I haven't noticed it at any reasonable power output.
So, I can't really see much reason, other than expense, not to put in some bigger caps. I don't really see how it can be "slow" as others have suggested. Amps just don't work that way.
But they're not going to fix weak bass.
-Nick
Time and time again people blame weak bass on lack of capacitance. I'm not going to suggest that more capacitance can't be a good thing. I built one of the audiosector kits, and it sounded just great with the small cap at the rectifier, and 1500uF per rail at the amps.
My new amp has 68000uF per rail. Supply ripple is around 12mV when playing a 20Hz sine wave at high volume.
I don't think I could really tell the difference between them.
With a good PSRR, I think the main difference you're going to see is earlier clipping, and probably some modulation at the line frequency. Obviously that's bad, but I haven't noticed it at any reasonable power output.
So, I can't really see much reason, other than expense, not to put in some bigger caps. I don't really see how it can be "slow" as others have suggested. Amps just don't work that way.
But they're not going to fix weak bass.
-Nick
Hartono said:"Maybe a buffer followed by a pot if you want weak sources to work"
which is a pre-amp ~~~~~~
Usually you want the buffer after the pot, or sometimes before and after (say if you have a very high output impedance source).
The reason is you want the power amplifier to have as low an input impedance as possible.
Cheers!
Russ
Hartono said:"Maybe a buffer followed by a pot if you want weak sources to work"
which is a pre-amp ~~~~~~
Well, technically, I think it's not since there's no gain, but really under that logic there's no such thing as a "passive preamp" unless it has a transformer, so I guess you can see it either way.
My point was that it's not a particularly demanding setup, so keep it simple.
Russ White said:
Yeah, maybe that's better. OTOH, with the pot on the output any unwanted noise in the preamp/buffer stage will be reduced by the volume control.
I suppose it really should be quiet enough not to matter though.
-Nick
Arx said:
Ah yes, indeed. Some preamps actually sound much better this way, a good example BOSOZ, and XBOSOZ often have a pot on the output, which will work just fine so long as the target power amp has sufficiently high input impedance.
The down side to this is that most amps THD increases with voltage output, and with the pot at the output the preamp will always be operating full scale. But it does reduce the hiss of the preamp very very well.
Cheers!
Russ
I've just thought to myself that since I'm ordering a new chip and two sets of resistors, and I have one spare rectifier board with diodes, I might as well built a second pair of amps and try bi-amping my new speakers.
Only thing is, I'm not entirely sure how to distribute input signal among two amps. Would it be ok to simlply solder input wires of the second amp to the same input sockets as the first's?
Oh, and by the way, it would be very nice to have some kind of source selector... I thought of using a simple double pole switch next to each pair of inputs (so that 'on' position would connect input signal with input wire, while 'off' would connect it to the groud). The downside would be obviously that if someone accidentaly put two switches on, some bad things could happen... Or maybe not? You tell me
Only thing is, I'm not entirely sure how to distribute input signal among two amps. Would it be ok to simlply solder input wires of the second amp to the same input sockets as the first's?
Oh, and by the way, it would be very nice to have some kind of source selector... I thought of using a simple double pole switch next to each pair of inputs (so that 'on' position would connect input signal with input wire, while 'off' would connect it to the groud). The downside would be obviously that if someone accidentaly put two switches on, some bad things could happen... Or maybe not? You tell me
"Only thing is, I'm not entirely sure how to distribute input signal among two amps. Would it be ok to simlply solder input wires of the second amp to the same input sockets as the first's?"
if you're doing passive biamping, basically you're correct. It's a good idea to use a buffer or pre-amp to avoid loading the source.
"Oh, and by the way, it would be very nice to have some kind of source selector... "
many way to do this, there's special rotary selector switch made for this purpose
Hartono
if you're doing passive biamping, basically you're correct. It's a good idea to use a buffer or pre-amp to avoid loading the source.
"Oh, and by the way, it would be very nice to have some kind of source selector... "
many way to do this, there's special rotary selector switch made for this purpose
Hartono
Yeah, You can just hook your source's outputs to both inputs. It will of course increase the loading on those outputs. As always, it depends on your source. Unless something is very poorly designed, nothing will break, but if your source isn't strong enough, twice the load is more likely to distort it.
As far as the switches go, a rotary switch is certainly better, or if you only need 2 sources you could get a dpdt switch to select which one.
If you want to do it with more than that, as you suggest, you'll want to leave the second half open, not grounded. Otherwise you're shorting your source. Most opamps are okay with that, but why push it.
As far as turning two sources on at the same time, that has some (though I would bet negligible) chance of causing damage. The two outputs will fight each other. Depending on their output impedance you'll hear one, the other, or some distorted mix of the two. If they're badly designed, maybe something will break. Extremely unlikely, but theres other ways just as easy without any danger.
A safer scheme for this would be to use the same switches in series each selecting either that source, or the next switch. In that case it would work exactly the same as your way, but if you turn on 2 at the same time, you just get the signal from the first one turned "on", and the rest of the chain is disconnected.
You could either skip the switch for the last device and have it as a default, or tie its pass through to ground and have a good quiet mute when everything is turned off.
-Nick
As far as the switches go, a rotary switch is certainly better, or if you only need 2 sources you could get a dpdt switch to select which one.
If you want to do it with more than that, as you suggest, you'll want to leave the second half open, not grounded. Otherwise you're shorting your source. Most opamps are okay with that, but why push it.
As far as turning two sources on at the same time, that has some (though I would bet negligible) chance of causing damage. The two outputs will fight each other. Depending on their output impedance you'll hear one, the other, or some distorted mix of the two. If they're badly designed, maybe something will break. Extremely unlikely, but theres other ways just as easy without any danger.
A safer scheme for this would be to use the same switches in series each selecting either that source, or the next switch. In that case it would work exactly the same as your way, but if you turn on 2 at the same time, you just get the signal from the first one turned "on", and the rest of the chain is disconnected.
You could either skip the switch for the last device and have it as a default, or tie its pass through to ground and have a good quiet mute when everything is turned off.
-Nick
OMG, one time you tell me that I should not short input and next - just the other way round
What does it actually depend on?I thought about rotary switch, but it would'n fit into my overall chasis design, so I'd rather go with pole switches.
I understand that signal wires from input selector all meet at volume pot?
And it won't have any drawbacks? Sounds like a brilliant idea (even though I don't understand it fully ).
As to my second GC - do you think I should buy a separate transformer for it? If yes, does it have to be a powerful trafo, or I would get away with a small one? Tweeters won't eat much current anyway, will they?...
At the moment my plan is to use GC on premium resistors with a 80 or 120VA transformer (I haven't decided about the voltage yet) and use it for driving tweeters. I would keep the 'standard' GC on 225VA trafo and drive the mid+bass sections with it. Does such config make any sense?
A bit more on topic: I found this (terribly expensive) shop with some of the most esoteric audio gear parts. And its selection of resistors drew my attention, particularily the most expensive ones, Shinkoh, as I can't find any information about them. Can a mere resistor be really worth that much? (£1 = about 1.95$)
).As to my second GC - do you think I should buy a separate transformer for it? If yes, does it have to be a powerful trafo, or I would get away with a small one? Tweeters won't eat much current anyway, will they?...
At the moment my plan is to use GC on premium resistors with a 80 or 120VA transformer (I haven't decided about the voltage yet) and use it for driving tweeters. I would keep the 'standard' GC on 225VA trafo and drive the mid+bass sections with it. Does such config make any sense?
A bit more on topic: I found this (terribly expensive) shop with some of the most esoteric audio gear parts. And its selection of resistors drew my attention, particularily the most expensive ones, Shinkoh, as I can't find any information about them. Can a mere resistor be really worth that much? (£1 = about 1.95$)
Yeah, Shorting inputs to ground is good. Outputs to ground is bad (usually).
I think the switches are a decent solution. I've never really seen it done that way, but have always had bad luck with rotary switches myself. If you wire it the way I suggested it should be safe for your source, and in some ways probably nicer than a rotary. If I ever need an input selector, that's probably how I'll do it.
If you want to try it anyways, I'd suggest you can probably get away with a much smaller transformer, or just use the same one. (I'm in the process of doing a triamped setup, all on one xfmr.)
I'd actually recommend the miniature Panasonic metal films. They're nice for point to point chipamps, because there's room to solder 2 of the 3 necessary resistors directly to the bottom of the chip, and still have clearance between them and the heatsink.
-Nick
I think the switches are a decent solution. I've never really seen it done that way, but have always had bad luck with rotary switches myself. If you wire it the way I suggested it should be safe for your source, and in some ways probably nicer than a rotary. If I ever need an input selector, that's probably how I'll do it.
Not really. Very slightly higher loading on the source (or buffer), but fairly insignificant. All it will do is lightly pull the input to ground when the input is disconnected, so it won't float around picking up noise. Keep in mind, if you're going to run without a buffer, that there's probably already a resistor to ground on the input, and adding another won't do much.uncle_leon said:And it won't have any drawbacks? Sounds like a brilliant idea (even though I don't understand it fully
I actually wouldn't suggest passive biamping personally. I think it's a waste of an amp. Active is another story, but then you need a crossover in your preamp or something.
If you want to try it anyways, I'd suggest you can probably get away with a much smaller transformer, or just use the same one. (I'm in the process of doing a triamped setup, all on one xfmr.)
It probably makes sense to people who believe in fancy resistors. I don't. Cheap metal films for me.
I don't want to start any arguments, but I think not. If you're that worried about tolerance, you're probably better off buying a hundred cheap ones, and matching them yourself.
I'd actually recommend the miniature Panasonic metal films. They're nice for point to point chipamps, because there's room to solder 2 of the 3 necessary resistors directly to the bottom of the chip, and still have clearance between them and the heatsink.
-Nick
Arx said:
I would recommend passive biamping. If you condsider the relatively low cost of adding two more gainclone stages to your existing supply, IMHO the benefits are very much cost effective.
I did exactly this in my current setup, My Mission 753's sounded quite a bit better. The bass was more solid, more controlled and the highs became more fluid and musical. The character of the sound changed substantially for the better.
Of course it was not "twice as good", but I would step outside for a fight with you if you took the extra two stages back off me!
Next stage is to build a further two and convert my 753's to triamps. Then the bass assist will have its own gainclone stages. I'm not sure wether the load might be too much for my smps array, if not I will build a second and run each channel off of four skynets each.
That is not to say that adding a filter(crossover) prior to the amps would not be the best solution, however I dont think I am ready for that project just yet
- I don't understand baffle steps, phase difference etc enough to know how it would effect my sound
- The missions are 2 way with bass assist (possibly) I haven't seen a filter project that gives this
- Active filters tend to use op amps, I dont want to spend time finding the optimum one just yet
- I just spent a few quid replacing the crossover componenets in my missions, I want to get some pleasure from the enhanced sound
- I have just built a 12 chip dddac, its so awsome, I will upgrade to 24 or 36 first
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Though Mission 753's with 10 gainclones and an active filter might just be amazing
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