Yung Plate Amp - Initial Impressions

I ordered and received the 200W with 6dB boost model, strictly for evaluation. Mainly I was looking to see if I can figure out the boost circuit, and identify the components needed for tweaking the subsonic filter for diy needs. Sadly, these amps are not DIY-friendly at all, so imo are not worth the trouble unless they fit your needs 'as-is'. Yung has taken some measures that make board removal tedius, and obviously warrany-voiding. Gluing the board in place, and using surface mount resistors that can only safely be replaced by removing the board, for example. Still, I will do my best to figure out the boost circuit, for those brave souls who spit in the eye of challenges like this. Or if someone out there happens to already have the schematic, even just the pre-amp, that would be awesome to share.

The amp itself seems to be very well made. I'll eventually give it a listen. I was surprised at the small size, even knowing the dimensions before it arrived.

For me, I'll stick to the BASH amps since the info for these is already available, and they are relatively easy to tweak.

 

EDIT:  After studying and working with these a bit more (and having my frustration of disassembly subside a bit), I've changed my mind about these.  It is possible to tweak the HPF on these relatively easily if desired, and it is possible to defeat the bass boost circuit if needed.  And I do like their smallish size, and good power.  You can read through the whole thread to see how the circuits were discovered, or jump to post 85-ish for a wrap up.

Edited by garciab - 12/30/12 at 11:25am

Kg,

I've gotten where I prefer the 'digital' type amps. Seems the a/b with the huge transformers always have some type of hum or mechanical noise. Once I tried a BASH 300, I was converted.

I just finished repairing a Keiga 300w for hum issues, and I have a SA240 from PE that I put in a friend's sub that hums as well. Gonna do a temporary swap with him to try to fix his amp. (Amp hums on its own, nothing else hooked to it, once it's powered on). I agree...they are easy to work on for modding the boost and such. But in my limited experience, they are a bit noisier and prone to noise/hum.

Hence my interest in finding another possible DIY-friendly 'digital' amp. Not that I NEED them to be tweakable, just that it's nice to have that option in case you want to move it to a totally different sub design. Being able to boost here or there, or move the subsonic filter is a great option imo.

Pro-amps are in another category all together. Does it happen to have a 3prong plug? Just curious. It doesn't help that users have to up the gain on them to achieve good output, so if it's a noisy design it will make matters worse. Best bet for these is to use a level booster, or take advantage of the balanced inputs if at all possible.

Reports like yours of hum...that's one of the main reasons why I don't explore the pro-amp universe. Plus, I prefer efficient subwoofer designs that give me max output with <500W. I may never achieve record-setting spls, but it gets me where I'm happy and smiling.

Quick update...I have managed to find the location of the boost circuit. It does not calculate to a full 6dB boost though, so it's either done in two stages or the specs are inaccurate. If you need details, send me a pm. Again I stress, these amps are not really DIY-friendly...removing the pre-amp board for these mods is quite a pain and will surely void any warranties it has. Unless I am blown away by the little 200W model, or unless they run a great sale on them, I'll stick to other models for my needs.

I am certain that the circuit applies to the whole line that PE carries. It's obvious the pre-amp board is identical in all models, only exception being that the 300W and 500W models add speaker-level inputs. This would have no bearing on the boost circuit. Also bear in mind that the boost circuit likely serves as the subsonic filter; the models with no boost simply have an Fc at or slightly below 20Hz with no boost above that.

I'd take N8's feedback, since he's compared both himself. I haven't traced the whole pre-amp yet, so I can't answer your tech questions. I'd say your hunches are probably correct.

N8 isn't the first to tell me that they have stronger output than the BASH down low. A vendor who sells both told me the same thing. As far as quality...it does look like a very well made amplifier. Can't compare components to the BASH, as I believe they are actually different technologies. The BASH feels a bit wimpy compared to the Yung, but that's likely due to the different types of power supplies needed for their respective tech. I think both a very good amps.

I haven't seen a schematic for any of their models, but I think it's safe to say that the models without boost have their high-pass set at or slightly below 20Hz, and those with boost are as advertised, except with 'undetermined' boost values.

Yes, I believe you are right. Though I'm not completely clear on if Fc and boost F are the same. Fc is usually at the -3dB point in the response, and the boost frequency (if Q is above 0.7) occurs above that. I don't know what the sim programs do with the values they require. If I'm wrong, hopefully someone will step in and correct me.

What are the vertical divisions in the graph, 3dB? What exactly was the setup for measuring this response?

Do you have an ohmmeter? Or a way to measure a couple of resistors? I'd like to know what R8 and R23 measure on your amp. They are easy to locate, near the top edge of the pcb where the led is.

Yes, the pcb is marked showing their location.