Well, you may be onto something there. My sources are not the greatest in the world (regular Sony CD/DVD player), but then again you have to start somewhere, right? Still, I would love to sit down with a bunch of speakers and figure out once and for all why this bass (or lack thereof) issue keeps coming up and what it is tied to.Peter Daniel said:Certainly the chipamps may work better with efficient speakers, but I also have a theory that they allow you to finally hear what your source equipment is all about and if it lacks the bass, that what the amps will show
BTW, is that a spalted burl you used on the sides of those cases? They are quite nice.
), if you take some other amplifier and have the tone controls in neutral, do you get more base? The LM3886 is capaable of base down to DC you know but your design may have some roll off but you deside where it should be.I just thought I'd add my experience of the gainclone.
I have tested a 'standard' ChipAmp kit with my brother's Dynaudio 1.3MkII's and there was certainly no lack of bass. The Dyns aren't efficient speakers, in fact they are supposedly difficult to drive but the gainclone kept control of the bass extermely well.
The gainclone had no active pre and actually out performed an Arcam A85 amp. The bass level and quality was virtually indistinguishable between the 2 amps.
I know that gainclones are suited to more efficient speakers but in my experience even difficult loads presented no problems for this remarkable little amp.
I have tested a 'standard' ChipAmp kit with my brother's Dynaudio 1.3MkII's and there was certainly no lack of bass. The Dyns aren't efficient speakers, in fact they are supposedly difficult to drive but the gainclone kept control of the bass extermely well.
The gainclone had no active pre and actually out performed an Arcam A85 amp. The bass level and quality was virtually indistinguishable between the 2 amps.
I know that gainclones are suited to more efficient speakers but in my experience even difficult loads presented no problems for this remarkable little amp.
What was this 'standard' configuration? Snubberized PS or no?waltona said:
Not necessarily more bass in a volume sense, but I did think a different amp had more presence and control in that area.
Johan (or Johannes) is actually very common throughout the world. I picked it up when I lived in Ethiopia.
ttan98 said:
I think that's an extra air effect rather than a bass boost. Neat tweak, though. Possible that it will amplify RF at infinity gain unless the input load also contains an RF filter, maybe 220pF ceramic disc?
Instead. . .
Normally, I'd use the brash sounds of metal for shunting components, and the softer sounds of carbon for pass components.
So, I've got to agree with Peter on shunting with metal, because it "subtracts" that type of sound and because it is safer for the amplifier to shunt a wider bandwidth than a smaller bandwidth.
On an optional pass component, howabout a 63uF 100v cap at position Ci, with a 47nF or 100nF ceramic bypass cap? That'll probably dodge the upper midrange.
To tilt your h2/h3 response in favoring some slamming bass, have your input filter cap at 1 octave below your speakers and have your nfb cap (Ci) at 1/2 to 1 octave below your input filter cap.
Wima caps are good at input, and easy to tell if its the right size (too big=weak bass and shouts, wheras right size rocks down the house while the amp stays cool).
See the overture design guide spreadsheet for more information.
This technique works best if you aim for stronger dynamics rather than stronger average SPL.
Here's another thought. Its already a good amplifier, and if popular music is the source, then what about the fact that no nightclub, concert, DJ, or even the wedding singer would ever be without an Equalizer, DBX120A and Aphex?
Sure you can (in order as above) alter the frequency response, tilt the h2/h3 response, and punch up the dynamics on your amplifier. Those efforts are really quite a sport--but there's an easier way.
Due to the conflict between bigger input filter cap/bigger rails caps making more bass, or smaller caps in those locations making better quality bass (and better quality overall), howabout a preamp with bass-n-treble controls plus adjustable crosspoints (4 knobs, bass, basspitch, treble, treblepitch)? That way you can set the amplifier for all-quality and then crank the bass whenever you want, in just the way you like it.
P.S. There is a possible problem if using the optional speaker output zobel. Polypropylene is too powerful and could make a sharp drop in the upper treble, possibly perceived as a louder midrange. I wish I had thought of this first.
Well, you can just use the cheapest, possible polyester "bubble" cap of 100nF or 200nF along with 2.2R, 2.7R, 3R, or 4R, and adjust to taste in regulating the desired taper on upper treble.transformer to use
Wonder if anyone would know if this transformer will work for the LM3875.
POWER TOROID
TRANSFORMER
120 VAC PRIMARY
SECONDARY TAPPED FOR 6 RAILS: +/-30, +/-46, and +/-51 VDC
EXCELLENT LINE AND LOAD REGULATION
Designed for a stereo power amplifier very conservatively rated 600 watts. The voltages are full-load values for continuous sine wave load tests. Toroidal core and multifilar windings provide very low external field and excellent regulation. Approximately 10 lbs weight. Center hole potted for easy mounting. Fast-on 1/4" female terminals on wire ends. UL recognized component. Supplied with schematic diagram and 1 rubber mounting washer.
--------I know its overkill, but its cheap and would it work well?
Wonder if anyone would know if this transformer will work for the LM3875.
POWER TOROID
TRANSFORMER
120 VAC PRIMARY
SECONDARY TAPPED FOR 6 RAILS: +/-30, +/-46, and +/-51 VDC
EXCELLENT LINE AND LOAD REGULATION
Designed for a stereo power amplifier very conservatively rated 600 watts. The voltages are full-load values for continuous sine wave load tests. Toroidal core and multifilar windings provide very low external field and excellent regulation. Approximately 10 lbs weight. Center hole potted for easy mounting. Fast-on 1/4" female terminals on wire ends. UL recognized component. Supplied with schematic diagram and 1 rubber mounting washer.
--------I know its overkill, but its cheap and would it work well?
Thanks for the suggestion. I'm trying to go a different route, though. I don't want to actually throw a lowpass filter into the signal path - that would be extremely unnatural, and I want a flatter frequency response. I guess that's what the carbon resistor would be doing anyway, though. That version just seems to extreme for me.danielwritesbac said:
I think that's an extra air effect rather than a bass boost. Neat tweak, though. Possible that it will amplify RF at infinity gain unless the input load also contains an RF filter, maybe 220pF ceramic disc?
Instead. . .
Normally, I'd use the brash sounds of metal for shunting components, and the softer sounds of carbon for pass components.
So, I've got to agree with Peter on shunting with metal, because it "subtracts" that type of sound and because it is safer for the amplifier to shunt a wider bandwidth than a smaller bandwidth.
On an optional pass component, howabout a 63uF 100v cap at position Ci, with a 47nF or 100nF ceramic bypass cap? That'll probably dodge the upper midrange.
To tilt your h2/h3 response in favoring some slamming bass, have your input filter cap at 1 octave below your speakers and have your nfb cap (Ci) at 1/2 to 1 octave below your input filter cap.
Wima caps are good at input, and easy to tell if its the right size (too big=weak bass and shouts, wheras right size rocks down the house while the amp stays cool).
See the overture design guide spreadsheet for more information.
This technique works best if you aim for stronger dynamics rather than stronger average SPL.
Here's another thought. Its already a good amplifier, and if popular music is the source, then what about the fact that no nightclub, concert, DJ, or even the wedding singer would ever be without an Equalizer, DBX120A and Aphex?
Sure you can (in order as above) alter the frequency response, tilt the h2/h3 response, and punch up the dynamics on your amplifier. Those efforts are really quite a sport--but there's an easier way.
Due to the conflict between bigger input filter cap/bigger rails caps making more bass, or smaller caps in those locations making better quality bass (and better quality overall), howabout a preamp with bass-n-treble controls plus adjustable crosspoints (4 knobs, bass, basspitch, treble, treblepitch)? That way you can set the amplifier for all-quality and then crank the bass whenever you want, in just the way you like it.
P.S. There is a possible problem if using the optional speaker output zobel. Polypropylene is too powerful and could make a sharp drop in the upper treble, possibly perceived as a louder midrange. I wish I had thought of this first.
Right now the uncontrolled bass doesn't seem natural, so that's why I want to try the snubberized/high capacitance version of the PS. To make it sound 'correct', not just boomy. I have bookshelves, and although they have 8" drivers, they're not subwoofers. A preamp with those controls would be pretty cool, though.I have a capacitor on the signal input, and I'm using it as a DC blocking cap. It's a Wima polypropylene film - 2.2uF, I think. It's a pretty big (physically) cap. With something like a 20k input resistance, I think that creates a filter that's around -3dB @ 6Hz (don't have my calculator at the moment). I don't think that would be a problem, though.
The Peter Daniel PCB/kit has a 22k resistor that acts as the input signal load, and another 22k that acts as a feedback resistor. I'll try replacing the feedback resistor with carbon and see what that does. If you think the shunt resistor should be metal film, I'll leave it that way for the moment. The highs are screechy and I want to soften them up a bit. If I added a 220pF ceramic disk to get rid of RF interference, would that go in parallel with the 22k shunt resistor?
Where exactly does that zobel component go? Does it get applied across the speaker outputs? The audiosector board has slots for zobel components, but I don't quite understand what it does. I am having a little bit of trouble with RF (I can just barely hear a radio station with my ear right up to the tweeter) so maybe adding an RC circuit across the speaker outputs would kill that frequency. Hmm....
While we're at it, I get a turn off pop. Can we fix that too?
johan851 said:The Peter Daniel PCB/kit has a 22k resistor that acts as the input signal load, and another 22k that acts as a feedback resistor. I'll try replacing the feedback resistor with carbon and see what that does. If you think the shunt resistor should be metal film, I'll leave it that way for the moment. The highs are screechy and I want to soften them up a bit. If I added a 220pF ceramic disk to get rid of RF interference, would that go in parallel with the 22k shunt resistor?
Where exactly does that zobel component go? Does it get applied across the speaker outputs? The audiosector board has slots for zobel components, but I don't quite understand what it does. I am having a little bit of trouble with RF (I can just barely hear a radio station with my ear right up to the tweeter) so maybe adding an RC circuit across the speaker outputs would kill that frequency. Hmm....
While we're at it, I get a turn off pop. Can we fix that too?
If you are replacing feedback resistor for carbon, you might as well go with carbon for input shunt.
It's best to place 220pF cap across inverting and noninverting chip inputs. I'm not sure about ceramic disc though, polystyrene might be better.
Zobel components are resistor (Rz) and capacitor (Cz) in series from output to ground. CarlosFM recommended 2R7 and 0.1uF, I noticed that Gaincard uses 10R and 0.1uF.
I'm not using Zobel, as it messes up the sonics.
dfdye said:BTW, is that a spalted burl you used on the sides of those cases? They are quite nice.
This is actually cork floor panels, they worked better than acrylic I used later in production models.
As to the burl, that amp uses Mardone Burl: http://www.diyaudio.com/forums/showthread.php?s=&threadid=76609&highlight= This is also the best GC I've built so far
Another example of burl in attached pic.
Attachments
johan851 said:
It is probably a problem. Are you getting an upper midrange peak, cramped soundstage, and undercontrolled bass?
Polypropylene caps go by near-exact sizes. For instance, the largest cap indicated is 0.7uF. That, rated for 10hz, actually affects 20hz. A larger cap could be amplifying non-audio signals, and is fairly certain to miss the sweet spot in its bandwidth (thus the upper mids can get a smoke-alarm coloration).
I've got that very same cap, by the way. It isn't 100% awful, but the little tiny blue Wima 100v work so much better. They do vary, as in each cap has its own personality; however, they're cheap to play with and some are so good there's no money that could buy better. It just takes a small collection (somewhere near the right capacitance size) and some time to play.
Values for electrolytics are different, and could vary between 4.7uF and 3uF. They sound considerably different, depending on their voltage ratings and many other factors. I believe that Peter favors Blackgate "N" 4.7uF. Note the physical size of that particular cap is above average (hint).
EDIT: Electrolytics have one really good feature for input filter caps, and that is if the connected source also has a DC blocker then the input capacitance won't suddenly drop to "undersize" like it could with poly caps.
P.S. Power thumps are usually that the input cable is providing a more attractive ground than the power ground. Sheilded cable can do that.
Peter Daniel said:As to the burl, that amp uses Mardone Burl: http://www.diyaudio.com/forums/showthread.php?s=&threadid=76609&highlight= This is also the best GC I've built so far
Another example of burl in attached pic.
Its beautiful.
danielwritesbac said:
I think that's an extra air effect rather than a bass boost. Neat tweak, though. Possible that it will amplify RF at infinity gain unless the input load also contains an RF filter, maybe 220pF ceramic disc?
Instead. . .
Normally, I'd use the brash sounds of metal for shunting components, and the softer sounds of carbon for pass components.
So, I've got to agree with Peter on shunting with metal, because it "subtracts" that type of sound and because it is safer for the amplifier to shunt a wider bandwidth than a smaller bandwidth.
On an optional pass component, howabout a 63uF 100v cap at position Ci, with a 47nF or 100nF ceramic bypass cap? That'll probably dodge the upper midrange.
To tilt your h2/h3 response in favoring some slamming bass, have your input filter cap at 1 octave below your speakers and have your nfb cap (Ci) at 1/2 to 1 octave below your input filter cap.
Wima caps are good at input, and easy to tell if its the right size (too big=weak bass and shouts, wheras right size rocks down the house while the amp stays cool).
See the overture design guide spreadsheet for more information.
This technique works best if you aim for stronger dynamics rather than stronger average SPL.
Here's another thought. Its already a good amplifier, and if popular music is the source, then what about the fact that no nightclub, concert, DJ, or even the wedding singer would ever be without an Equalizer, DBX120A and Aphex?
Sure you can (in order as above) alter the frequency response, tilt the h2/h3 response, and punch up the dynamics on your amplifier. Those efforts are really quite a sport--but there's an easier way.
Due to the conflict between bigger input filter cap/bigger rails caps making more bass, or smaller caps in those locations making better quality bass (and better quality overall), howabout a preamp with bass-n-treble controls plus adjustable crosspoints (4 knobs, bass, basspitch, treble, treblepitch)? That way you can set the amplifier for all-quality and then crank the bass whenever you want, in just the way you like it.
P.S. There is a possible problem if using the optional speaker output zobel. Polypropylene is too powerful and could make a sharp drop in the upper treble, possibly perceived as a louder midrange. I wish I had thought of this first.
Many users including myself reported that metal film feedback resistor causes the sound from the top end to sound harsh. Hence the suggestion to use carbon.
An enginnering approach is to use a low pass filter at the input, 1k and 1.5nF(110KLP) at the input, this is used by Linkwitz's 3886 chipamp.
Do you have a part number or model number? And maybe a range of capacitances to look for? I'm worried about using too small a capacitance. The RC circuit formed by that input cap has a resistance equal to the output resistance of the preamp plus the input resistance of the gain clone (around 22k due to the shunt resistor, yes?). So that's about 0.5 + 22k = 22k. Once the cap's capacitance hits about 0.2uF, we have a filter that does -3dB at 30Hz, and we don't want to move that highpass filter's corner frequency up any further...
Unless the cap gets put between the shunt resistor and the chip input instead of before both?
The DC offset from the preamp isn't bad - maybe 3mV max. Maybe I'll just bypass the DC blocking cap to see if that makes it any better.
I would imagine that 2R7 and 0.1uF would mess up the sonics quite a bit - that would short a lot of audio frequencies through the zobel. The 10R and 0.1uF setup shouldn't, though. It would only get rid of stuff up around 150kHz and above. Did you try it with 10R and 0.1uF and not like that either?
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