My board is also marked V1.1. The resistors in the zobel network on my board are 100R, not 1K. When I measured them on-board they all measure 71R, not surprising since they are still connected to the circuit.
EDIT:
I had a chance last night to do a bit more listening. My initial thoughts (recorded above) were of overall good sound quality. There is a lot of power available (I'm mostly a tube guy so to me 15 watts is good so take that with a grain of salt). Listening longer and using some of the CDs I like for evaluating systems I'm finding it a bit too forward in the midrange and treble.
At first I thought it was lack of bass but the bass is there, it is just being "masked" by the mid/treble. I haven't had a chance to put it on a scope or chart frequency response but listening with different speakers and comparing to some other amps there is a definite boost in the mid/treble. For some music it is hardly noticeable, while on other music it stands out starkly. Hmmm.
EDIT:
I had a chance last night to do a bit more listening. My initial thoughts (recorded above) were of overall good sound quality. There is a lot of power available (I'm mostly a tube guy so to me 15 watts is good so take that with a grain of salt). Listening longer and using some of the CDs I like for evaluating systems I'm finding it a bit too forward in the midrange and treble.
At first I thought it was lack of bass but the bass is there, it is just being "masked" by the mid/treble. I haven't had a chance to put it on a scope or chart frequency response but listening with different speakers and comparing to some other amps there is a definite boost in the mid/treble. For some music it is hardly noticeable, while on other music it stands out starkly. Hmmm.
Mine measured 1k, so I've changed to 10r with 0.47uf. Added 0.22uf across the output as well..Changed the 1k input resistor to 4.7k to prevent input overload, still may need higher value? Running it with 14v power supply. Removed channels 2 and 3 (3 was the noisiest on mine.
Works best with less efficient speakers.
Also using with no input caps and DC at output is less than 20mv all volumes..
Works best with less efficient speakers.
Also using with no input caps and DC at output is less than 20mv all volumes..
Attachments
Just got home, I also have the v1.1 board, and it appears to have the same value resistors (gold-black-black-brown)...
I'm just about to hook it up an start listening to some tunes...
Just a quick question, what PSU is that in the pic posted above? Is it 24v?
I'm tempted to try mine from the 12v line of a computer PSU just for testing...
EDIT: sharpi31 - I ordered mine on the 17th, so I'd expect to wait at least a week.
I'd almost forgotten about it until it arrived today!
I'm just about to hook it up an start listening to some tunes...
Just a quick question, what PSU is that in the pic posted above? Is it 24v?
I'm tempted to try mine from the 12v line of a computer PSU just for testing...
EDIT: sharpi31 - I ordered mine on the 17th, so I'd expect to wait at least a week.
I'd almost forgotten about it until it arrived today!
I'm listening to mine now thru some car speakers rattling around all over my desk. 
I can hear some very slight hiss if I put my ear right up to the speaker, but these speakers aren't very sensitive, so it could be louder with high efficiency speakers.
I can hear some very slight hiss if I put my ear right up to the speaker, but these speakers aren't very sensitive, so it could be louder with high efficiency speakers.
The bass doesn't sound too bad to me... I've got a load of 10KuF caps that I can try out, I'm guessing the place to add a cap would be in the power input?sharpi31 said:
audio1st said:
I'm going to change the zobel values on mine as well but probably won't be able to get to till Thursday. I'll report back with any changes in sound. I may also bypass the input cap. (Doesn't using the jumpers bypass it? I can't remember and will have to go down to the bench and check.) If not I'll desolder and jumper.
I'm using a 24V PS with mine for testing. It is only 3A but should be fine for two channels I think.
The physical size of the 1uf (105 marking) capacitors in the Zobel networks on my board means that it is likely that the dielectric is Y5V (or Z5U). This has a huge variation in its dielectric-constant with applied voltage, meaning that the capacitance changes wildly as the voltage across the cap changes. Whether this has any effect on the sound when used in a Zobel network is debatable, but there appears to be enough room to put a stacked-layer polyester part in, (or as I have some nice 1uF 50V X7R SM parts in front of me here at work, in a 1210 package, I could try those).
X7R is a much more stable dielectric than Y5V. There is still a 10% change is capacitance between 0V bias and the maximum dc bias, but that's not much when you compare it to the 80% change you get with Y5V!
X7R is a much more stable dielectric than Y5V. There is still a 10% change is capacitance between 0V bias and the maximum dc bias, but that's not much when you compare it to the 80% change you get with Y5V!
sharpi31 said:
Without sweeping it on a scope I can't say with absolute certainty but listening tests indicate that the bass is there. It isn't as if there is a rolloff as one would get with a simple cap/resistance network. It appears the lowest bass is there but the midrange is being accentuated. It is also possible that the bass below a certain frequency is being evenly attenuated rather than rolled off.
I hope to get some time tonight to do some more tests. Time to pull out the Rives test CD and also fire up the function generator. Perhaps even a comparative SPL test between the Surefire and a Gainclone with a decent pair of speakers. All depends on available time!
Ouroboros said:
I'm partial to polyester for zobels though I've also used polypropylene. Tonight I'm hoping to have some time and I'll go through my cap box and see what I have that might fit.
Yep, it's surprising how little power this amp uses when you turn it up...Sherman said:
I'm now running mine from a 19v laptop PSU (Rated at 6.5A), and it's doing a great job, with 4 channels....
I only think you'd need 13A if you were running 24v, at 4 ohm loads, and cranked right up!
Anyway, I copied your cap idea, and added 3 x 10000uF Rubycon caps to the power input... It seems to make it sound a little better IMO, but then again it could be placebo...
My rig isn't quite so well organized, wires everywhere, but it works... Sorry for the bad pic quality:
Attachments
Yep, well spotted.theAnonymous1 said:Is that an iRiver H120/H140 I see?
It's an H140.I've found the line-out sounds nice when playing FLAC's and high bitrate OGG's... It's sat on the volume control right now (little mixing desk).
I guess it would sound better if I just used a pot, but the desk is handy as I've got low-cut when I don't want to annoy the neighbours.
MikeHunt79 said:
Yep, well spotted.
I've found the line-out sounds nice when playing FLAC's and high bitrate OGG's... It's sat on the volume control right now (little mixing desk).
I guess it would sound better if I just used a pot, but the desk is handy as I've got low-cut when I don't want to annoy the neighbours.
You wouldn't want to trade it for a well kept H320 would you?
You could even swap drives to keep it 40GB.
I use the digital out on it for my headphones rig, so I'd rather keep it really... I do see the odd one on e-bay tho...theAnonymous1 said:
You wouldn't want to trade it for a well kept H320 would you?
You could even swap drives to keep it 40GB.
This amp seems pretty identical to 41Hz's AMP9 kit... Does anyone know how the two compare? The 41Hz kit is a little more expensive, but they throw in 3 x 15.000 uF caps, and also it uses toroid inductors instead of the cylindrical ones used on the Sure-Electronics amp.
I must say, the more I listen to this amp, the better it sounds! It sounds really neutral to me... This is my first Class D amp tho, most of my other amps are run of the mill store bought ones (apart from a quad 405)...
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.