Hi Klaus, thanks for the info, I have 4x 0.47uf FT-3 on the output of my Yaquin CD1 which goes to my charlize2, its the min I can get away with before bass rolloff. Seems to work fine so I was wondering to try it with the TC2500, just worried about damaging it.
I haven't tried Siemens Sikorel before, are you using them on your Charlize2, 220uf seems very high if you mean input caps on your TC2500?
cheers David
I haven't tried Siemens Sikorel before, are you using them on your Charlize2, 220uf seems very high if you mean input caps on your TC2500?
cheers David
Yes I tried them in four of my Tripath amps and they are way superior to my
Auricaps, Mundorf, various Wimas, BlackGate N 2uf, Russian Teflon and all others I tried that I can't remember right now. The clarity and spacial representation really surprized me. With the addition of the Silvermica, they are all that I have been searching for. I have not compared them to the
Mundorf Silver Oil or the V cap though, as these are way to expensive for me.
I came to try this type of setup after someone on a German forum paralleled
220 uf with 2uf BlackGate and two 0,1 uf BlackGates back to back and reported better results with his Pass Amp, then the Mundorf Silver in Oil and
other expensive caps.
Klaus
Thanks Klaus, wow, what do they put in them pixie dust? I found some on ebay and will try some.
While we're on the subject of input caps, does anyone know how to calculate the rolloff points for various cap values?
Is it basically an RC filter? If so, what's the R value, 100k?
I want to have a tweeter wired directly to the output of this amp, so I figure a 0.1uF input cap could be used as a HPF (to protect the tweeter, I'm using an active XO) and also get rid of any turn on thump without having to resort to a relay or any other extra parts.
Are there any flaws in my plan here?
Is it basically an RC filter? If so, what's the R value, 100k?
I want to have a tweeter wired directly to the output of this amp, so I figure a 0.1uF input cap could be used as a HPF (to protect the tweeter, I'm using an active XO) and also get rid of any turn on thump without having to resort to a relay or any other extra parts.
Are there any flaws in my plan here?
R is the same as Rin - 22KOhms in most cases. IIRC the specific equation is in the Tripath chip datasheet.
Using a small cap on the inputs when you're only driving a tweeter with the amp is a good idea. Saves amp power and limits bass excursion in the driver, I'd say. Just double-check that the tweeter doesn't require a series cap of some sort for some other reason than just attenuation of certain frequency ranges.
(I have no real idea about tweeters but a cap can do other things besides rolling off frequencies - guess it might be used to block random output DC or something similar at the output. But I must maintain that I don't know - just guessing.)
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That's exactly how I want to drive my horn system, but I still don't have the guts to risk my tweeters. My only fear is the moment of switching it on. I killed both of my FE127 within 2 Seconds at turn-on. I don't know what happened. As long as I was using just one battery all was fine. Then with two at 24 Volts I killed the speakers. Where did all that DC suddenly come from? So I don't fully trust the Shure boards yet.
If there was a sonically transparent way to limit the amperage on the output, I would do it in a beat. I got three Shure bords waiting to be used
this way, but there is to many dollars at risk.
A big plus using this kind of crossover is, that we can use our favourite cap for each band. Pure silver mica caps are unbeatable for frequencies above about 2k but the cost is outrageous when the whole frequency band needs to be covered. 0.03uf for about 2000hz is however very affortable.
Greets,
Klaus
What about an output protection relay?
The 41Hz Amp4 has an on-board relay that uses signaling from the chip to open / close. This would be implementable as an external relay board. Incidentally 41Hz sells a power-supply board that has a relay. Haven't tried it but it's worth a look: 41Hz Audio😛S1 Power supply board kit
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Short
If you eliminate the input cap on a Sure 2x100 you will be shorting the 2.4v dc offset adjustment to ground through R14/34 and your attenuator if you use one and sending voltage back to the output of your source or pre which will most likely end with a device, not a cap.
I use 0.1uF caps to drive my midrange horns with Tripath. Works great. That makes a high pass of about 80Hz. I use no cap on the output. For a tweeter you could go even smaller.
You have to have a pair of caps between two devices. Does it matter which one the caps are physically soldered to? Thats my question.
Excellent, I just happen to have 0.1uF caps to hand, I may go smaller later on however.
Right now I'm using two modded Lepai's to biamp, I've bypassed the tone controls and switched out the input caps for 2.2uF caps, and my tweeters have survived so far... but my tweeters are not expensive to replace however, but I'd rather avoid it possible.
Do you think it was DC offset that killed your tweeters? This may have been caused by a higher or lower input voltage, as Sure adjust the DC offset pots for an input voltage of 30v AFAIK. This is a good reason to go for a SMPS over a battery or linear PSU, as the voltage of a good SMPS will always stay fixed even when the mains voltage is not.
I'm crossing over to the tweeter at 2.7Khz, so a 0.03uF cap sounds like the one to go for. I must admit, I've not really researched silver mica or any other high end caps, but you may a good point that the lower values are far more affordable, so I think I'll give them a go. 😎
Hi, I missed your post earlier, the tweeter was originally in an active speaker which was biamped and had no cap on the output. I'll have to check the old PCB to be sure tho.
I ran thru the equation on the Tripath datasheet, and it appears the lowest value I can go is 0.02 ohm.
I found this site is also quite helpful regarding where bass rolloff starts to occur compared to the corner frequency:
Input Capacitors for Headphone Amps
0.02 uF, you mean? Yeah, that should give you a HP of about 400Hz. No worries.
At small values like that you can use PIO, Styrene, Teflon and stuff like that without breaking the bank.
At small values like that you can use PIO, Styrene, Teflon and stuff like that without breaking the bank.
Just remember that you get phase distortion well beyond the break frequency - up to around 10 times the break frequency, actually (phase shift is 45 degrees at Fb and roughly linear between 1/10th Fb and 10 times Fb). Worth oversizing your caps a little as a result.
Did you leve the active stage untuched? I have bypassed the whole active stage on my Lepai and it makes quite a difference on the sound.
With my friends Lepai I exchanged the OpAmps to THS 4082 and it sounds even better than mine. I don't know why though. Bypassed should logically sound better, but it dosen't. The THS 4082 is my fafourit OpAmp and it keeps amazing me.
I killed both Fostex FE127 in my Fonkens, it was not a tweeter. But that scares me all the more. Yes, it was DC, I saw the membrane moving out to
the mechanical limit. That was not a good feeling. I spend quite a bit time
to mod them, and they were sounding great in the Fonkes.
The 0.03uf was just a wild guess, because most people complain about the bass if they go down to 1uf on the Tripath amps. So I concludet that the rollof would be around 50-60hz with 1uf.
I would start with very small numbers and work my way up to the desired
roll off of the tweeter.
Yep, I meant 0.02 uF... 😱 I don't really know much about these exotic caps, and it does seem like quite a hot topic to some people... I think I'll keep my 0.1uF normal caps on hand and compare, as I'll be interested to see if I can hear any difference on my setup.
I'll go for 0.033uF then, thanks.
I bypassed the opamp totally. I had silly amounts of turn on thump before this...
🙁 Not good... What power supply were you using?
I guess at times like this is would be nice to have a variable capacitor handy. I find there is noticeable bass rolloff when this amp is stock, going to 2.2uF is probably the first mod I do when the amp is being used for fullrange speakers.
For tweeter use, I'm going to try the 0.1uF epcos and wima caps I already have so I'm going to give these a go until I get some 0.033uF caps.
I can recommend using a digital parametric equalizer to find the point just-right point for the bass cut. This really works very well.
You just put a big cap in that doesn't cut much of anything. Then fire up a parametric equalizer and add a single low-cut, nudging it upwards until you start noticing a loss of bass. Then pull it back a little and turn the EQ on and off to find the point where the EQ is cutting useless frequencies without negaitvely affecting the sound. Then just write down the corner frequency and find a cap that gives you approximately that frequency in the input LC filter.
I've tried something like this for the Cyburgs Needle I built, finding a nice, tuned below-45Hz cut that seemed to help the driver do its job by releasing it from handling useless inaudible low bass.
... by "digital parametric equalizer" I mean a computer-based software EQ. There are quite a few good free parametric EQ plugins out there.
Be careful with 0,1uf, that is very risky. Do you have 0,01uf ones that you can parallel until the desired rolloff?
Klaus
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