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Yung Plate Amp - Initial Impressions - Page 4

post #91 of 105
1/4/13 at 3:37pm
Quote:
Originally Posted by alphaiii View Post

It'll be great to know where the actual filter is on the non-boost versions.
I measured a 500W no boost Yung. R23 = 57.6k and R8=10k.

That gives a Q of 1.2 and a Fc of 30.14Hz. F3 is ~22Hz with a boost of ~2.4dB centered at ~38Hz. Of course this is based on the assumption that the boost circuit isn't also influencing things. I'm somewhat skeptical of this since the components of the boost circuit are populated on the board.
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post #92 of 105
1/4/13 at 10:16pm
Quote:
Originally Posted by garciab View Post

Yes, something is definitely wrong. Give the amp a good visual inspection to make sure there is nothing touching that shouldn't be, like a couple of components leads shorted, or something touching the metal plate. It's about all you can do. Hope it's something as simple as that.

I inspected the board with a magifying glass for 2 hours and there was no shorts. At least from all things im able to see.
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post #93 of 105
1/5/13 at 8:48am
Thread Starter 
Quote:
Originally Posted by Stereodude View Post

So, does the supposedly boost free version still need C13 and C14 of the boost circuit shorted in order to get a flat response controlled only by R8 and R23?

My recommendation is 'yes'. I'll trace my 300W non-boost version to be sure. I suspect it will still have a boost circuit, but the boost will be so attenuated that it will not affect the stock HPF. However, if one modifies the HPF, the little boost may still have an effect on the FR. Best to know for sure that the boost circuit will have no effects on the FR that you are trying to achieve.
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post #94 of 105
1/5/13 at 8:54am
Thread Starter 
Quote:
Originally Posted by Stereodude View Post

I measured a 500W no boost Yung. R23 = 57.6k and R8=10k.
That gives a Q of 1.2 and a Fc of 30.14Hz. F3 is ~22Hz with a boost of ~2.4dB centered at ~38Hz. Of course this is based on the assumption that the boost circuit isn't also influencing things. I'm somewhat skeptical of this since the components of the boost circuit are populated on the board.

This confirms that all of the PE Yung amps share the same HPF. And they all do have some type of boost. On the non-boost models, I believe the boost is so attenuated that it won't provide much boost at all. But no way to be sure until the signal is traced. I traced this on my CSS 500W, and that was the case. But on that amp, the boost actually helps the boost frequency of the HPF (around 34Hz). It was a huge difference in boost amount between the CSS 500W and the PE 200-6, so I don't believe the CSS is considered a boost model.
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post #95 of 105
1/5/13 at 8:56am
Thread Starter 
Quote:
Originally Posted by javygonx View Post

I inspected the board with a magifying glass for 2 hours and there was no shorts. At least from all things im able to see.

Well that's unfortunate. Hopefully you'll be able to resolve the problem with the seller or through PE.
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post #96 of 105
1/5/13 at 6:55pm
I hope so too. Sd300 is on backorder until march. As soon as the seller send me back the money I think I will place an order and get the boosted version frown.gif
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post #97 of 105
2/16/13 at 7:29am
I own the Yung 500-6 model i already bypassed the Bass boost circuit but i don't know what resistors i need to use to change the HPF to something like Fc of 20 or 19 if anyone can help .
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post #98 of 105
2/16/13 at 8:16am
Thread Starter 
For Fc of 20Hz, q of .7, R8 = 25K, R23 = 50K

For Fc of 18Hz, q of .7, R8 = 28K, R23 = 56K

Notice the ratio of 1:2 for a Q of .7, which is maximally flat response. And you can see what happens to Fc as the resistor values increase.
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post #99 of 105
2/16/13 at 8:50am
One question. Dont you like the +6db boost? Im just trying to collect info to make sure which Yung model get; if the boosted or non-boosted. Im inclining more in the non boosted version; but want to know your thoughts..
Thanks
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post #100 of 105
2/17/13 at 5:53am
thanks for your help garciab as for
Quote:
Originally Posted by javygonx View Post

One question. Dont you like the +6db boost? Im just trying to collect info to make sure which Yung model get; if the boosted or non-boosted. Im inclining more in the non boosted version; but want to know your thoughts..
Thanks

No I didn't like the bass boost it overexurted my sub caused allot of distorsion but as soon as I bypassed the bass boost everything sounded allot better. if I were u I'd get the boosted model and bypass the bass boost its a five minute job and u save a bit of money.
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post #101 of 105
2/17/13 at 7:27am
Oh wow. Thats interesting. But I have no idea how to do it. Would be nice to add pics and explain how to do it.
Thank you.
Edited by javygonx - 2/17/13 at 7:52am
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post #102 of 105
2/17/13 at 8:15am
garciab already explained how to do this.
Quote:
Originally Posted by garciab View Post

So here is a wrap up regarding the frequency response of this line of amps. We know that all the boost models share the same HPF (subsonic, rumble filter, etc), and it is set at 30Hz with a little boost above that. We also know that there is a seperate bass boost circuit to give the boost that is spec'd for each model. The HPF and boost are summed (combined) to give the overall frequency response (plus the phase and low-pass adjustments of course). So for those still interested in these, and having the desire to modify/customize the response, here are a couple of pics to help. Best thing to do is to defeat the boost circuit altogether, then tweak the HPF as desired, and as is common with other plate amps.

This pic points to the two resistors that need to be changed to tweak the HPF. They are located close enough to the edge of the pcd (near the led) that it shouldn't be too difficult.



This next pic is the back of the preamp pcb, and shows the two jumpers needed to defeat the bass boost circuit.



Here is the frequency response of my 200-6, after defeating the bass boost circuit, and modifying the HPF to an Fc of 13Hz, Q = 0.6.



We haven't had any user feedback about the non-boost models, but my suspicion is that they share the 30Hz HPF, but their boost circuit is configured for no boost. I will try to confirm this when my backordered 300W model arrives.
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post #103 of 105
3/2/13 at 1:30pm
Subscribed!

I just bought an SD500 second hand and tested my new LMS-R 12 free air with a tone generator app... I couldn't figure out why excursion fell off rapidly below ~30hz! I tried the same with my Bash300 and excursion looked normal to below 20Hz. Now I know why!

garciab, what resistor values did you use to set your fc to 13Hz? This is exactly what I would lke to do as my build will be good down to the mid-teens. Thanks!

Also, does anyone see any reliability issues with modding the HPF? I can't imagine WHY a company would put a 30Hz HPF on a subwoofer plate amp, but durability might be a reason for it. Thoughts?
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post #104 of 105
3/3/13 at 6:17am
Thread Starter 
R8 = 43k, R26 = 84k, values in this area should give you Fc = 12Hz ,Q of 0.7.

You do bring up a good point about affected reliability. If you read the hype of PE's site, you'll notice how Yung touts the amps ability to run full power for hours without shutdown problems. But we know their heat dissipation will be affected if we run then sub 20Hz. And heat is not a friend of electronics. Still, soundtracks are very dynamic, so as along as we aren't running sinewaves through them continuously, I think we'll be ok. But taking the risk is an individual determination.
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post #105 of 105
3/3/13 at 7:52am
Quote:
Originally Posted by garciab View Post

But taking the risk is an individual determination.

I'm more worried about screwing the amp up by modifying the filters than overheating it - I live in a townhouse so high SPL listening is not often. Also, this sub is used 99% for HT, the nature of which is pretty infrequent LFE.

Thanks a bunch for working this out! This is extremely helpful. One of the hardest things to find out about an amp is the value of any subsonic filtering involved. Now I can set it myself!
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