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Just thought I'd bumped this thread back up for anyone interested in modding the Yung. Thanks to bgarcia17 it can be done. I finally got my wife's new laptop up and running REW (using a EMM-6 with its calibrated file) and took a couple quick measurements from the two main seating locations in the room (they are about 5 feet apart). The response is a bit lumpy but that's because correcting for one position will only degrade the response at the other position... she sits in one position and I sit in the other so just like with any good marriage, good sound is about balance and compromise. The room is untreated and the sub is crossed at 100Hz... I've dropped the sub level down 3dBs since taking these measurements... the bass response is just bodacious!
 

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Thanks, I was quite surprised by the final performance of it all. I originally set out to buy a cheap used sealed sub for my 'wife's theater' upstairs in the "good" room where aesthetics reign supreme (no bulky acoustic treatments allowed and very limited placement options... however we do have a basement theater which is mine to do with as I please). As I searched for a cheap sub, all I could find were not even good enough to keep up with the mains (some vintage Infinities, RS series) and the sub had to be sealed to blend/integrate properly so most didn't even go low enough compared to the Infinities to make the purchase worthwhile. Then I got PMed a couple offers from several in the DIY community, however when I tried to model their builds myself in WinISD I could immediately see a number of problems with the choices they'd made and I could understand why they were trying to sell them off. Finally I just decided to try and see if I could just build one myself for under $500... and the above sub was the result except that it cost me under $350 to build it completely right down to the fake veneer, screws and glue. The final key to its performance came from this thread... from bgarcia's helpful info on tweeking the Fc. In the end I replaced R8 with 56K and R23 with 110K and it made a world of difference it the low-end grunt... I still can't believe I'm getting all this bottom end from a sealed 12" sub and its all pretty clean too.
 

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So what is the verdict on fc, Q and order for the highpass filter on a standard yung 500-6?
Basically what parameters inputted in to winISD will give realistic values.

Thanks!
 

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Unfortunately, there is no clear answer for that. I'm not familiar with winISD, so I don't know if it's possible to input both an HPF and a boost section.
 

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All I can tell you is what I inputted into WinISD Pro to model the amp... its not perfect but seemed to be close enough for my purposes:
under the EQ/Filter tab:
HPF: Butterworth n=3 Fc=23Hz
LPF: Butterworth n=4 Fc=185Hz
Boost: Peaking 2nd order highpass Gpk=8dB fpk=25Hz


my modeling of the amp's response after replacing R8=56k and R23=110k was to change the HPF: Butterworth n=2 Fc=9Hz
 

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All I can tell you is what I inputted into WinISD Pro to model the amp... its not perfect but seemed to be close enough for my purposes:
under the EQ/Filter tab:
HPF: Butterworth n=3 Fc=23Hz
LPF: Butterworth n=4 Fc=185Hz
Boost: Peaking 2nd order highpass Gpk=8dB fpk=25Hz


my modeling of the amp's response after replacing R8=56k and R23=110k was to change the HPF: Butterworth n=2 Fc=9Hz
I think I am going to order the resistors and reduce my hpf down to 20 from 30 hz. Would like a little bit more low end grunt. I have a tc epic 12 sealed.

So are u still happy with your modification? From memory u left the boost alone and made fc 18hz? Do anything different?
 

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Oh no, I decided to 'live on the edge' and went with values to give it Fc=9Hz... its not as wicked as it might first seem it would be once you stop to look at the modelling of the whole sub (meaning the natural roll-off of the driver and enclosure together with the amp's response). I actually went through a number of iterations of literally (soldering) swapping out different resistor values to convince myself that I could trust the models... in the end I tried Fc of 11Hz, 12Hz, 16Hz, 18Hz and finally 9Hz but also I tried using different ratio's of values (to change the cut-off slopes) and finally settled on 2:1, now I'm done... I believe I've finally found what works the best for my combination. Yes, I left the boost alone but only because I don't know how to change it other than to by-pass... I would have liked to have moved it to 23Hz just to see if it could give me a slightly better extension and balance but really its already in a pretty good place, so yeah I left it alone.

My Qtc=.63 ...so what's your enclosure volume? (If its 2.2 to 2.5 cu-ft you might consider a 9Hz Fc also, I just checked it out and it seems to model with a nice extended response)
 

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Oh no, I decided to 'live on the edge' and went with values to give it Fc=9Hz... its not as wicked as it might first seem it would be when you stop to look at the modelling of the whole sub (driver, enclosure volume, amp response when they all combine). I actually went through a number of iterations of literally (soldering) swapping out different resistor values to convince myself that I could trust the models... in the end I tried Fc of 11Hz, 12Hz, 16Hz, 18Hz and finally 9Hz but also I tried using different ratio's of values (to change the cut-off slopes) and finally settled on 2:1, now I'm done... I believe I've finally found what works the best for my combination. Yes, I left the boost alone but only because I don't know how to change it other than to by-pass... I would have liked to have moved it to 23Hz just to see if it could give me a slightly better extension and balance but really its already in a pretty good place.

What's your enclosure volume?
My enclosure volume is about 1.7ft3 and I have it stuffed with polyfill. I ordered that resistor kit last night so I'm looking forward to having a play with it. Will probably start with the 18hz fc like you had, then see were I go from there.

Also, how much of an impact does the AUDYSSY have on sound/listening experience? Does AUDYSSEY adjust the SPL or signal strength to the sub based on what frequency it is sending in order to give it a flatter SPL vs frequency response?

Reason I ask is because I still have a old JVC A/V unit with no auto programming capabilities. Got it for super cheap 2nd hand while i decide on what i want for a permanent setup.

Also what kind of microphone did you buy so you could generate the graph you posted on the top of the page? looks like a handy tool to have when messing with this stuff. Sorry for all the questions, just trying to expedite myself up the learning curve!
 

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The degree of impact Audyssey would have would obviously depend upon what your current in-room response is but I've been a believer in using Audyssey to help correct for in-room anomolies in freq and time domains for a long time now. I try to dial in distance (phasing) and set final calibration levels by REW (observation) rather than relying solely on Audyssey (although Audyssey will put you in the ballpark). My best understanding of Audyssey is that it only attenuates peaks and doesn't really boost but the real power of it is in its computational assessments of compromise between the seated locations to arrive at a best case 'sweet spot' to encompass a designated seating area... its better and MUCH FASTER than I could ever do it by observational tweeking (back in the days of trying to tweek everything with a BFD1124).

For a while (like about the last 5 years) I used a RS digital SPL meter with the correction file to take all my REW measurements. Then a year or so ago I purchased a EMM-6 (with individual calibration file) and a mic stand from Parts Express and a USB Dual Pre offa eBay then just let it gather dust while I continued to use the RS meter with REW until... this past Sunday, I broke out the mic, stand and the USB preamp and loaded REW into my wife's laptop (she was outta town) and took those measurements I posted above. Only AFTER taking those measurements I posted did I begin to tweek things in by observing the responses in REW. I love REW... its very difficult to get a sense of what's going on between your electronics and the room and how it all interacts without being able to visually measure the final acoustic effect in the room from where you sit. Over the years its allowed me to learn so much about my acoustical spaces (mainly down in the basement theater where I have an outrageous amount of room treatment in several forms).
 

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I read through this entire thread and still have a question...

I own the Yung SD-500 amp with no boost. What is the actual high pass filter set at for this particular amp? Is it really 30hz? 2nd order?

If I were to model this amp in WinISD, what settings in the filter tab in WinISD would work well?

Thanks for any help provided.
 

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Using stock component values, the HPF models at Fc = 30.139Hz, Q = 1.2. It is considered 2nd order, but the Q dictates the rolloff. I don't use WinISD, but I'm assuming you can enter Fc and Q values.
 

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Hi,
Thanks to bgarcia for your work on modding this amp, I am going to defeat the boost. But how do you go about lowering the crossover point? I run my main speakers full range and I'm good down to 40 Hz in room so I only need to augment below that. With the control set to 40, I'm still getting too much from the sub at 40 -50 but not enough at 30. My bandpass sub measures -3db at 28 and 90Hz. Ya, I'll still be missing the last 10 Hz or so, that will take a bigger sub and more power...
 

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I'm not clear on whether you want to lower the low-end (the HPF) or the high-end (the knob-controlled LPF) response of the amp. To lower the HPF, you'll find pics and details here regarding having to replace R8 and R23. If you need help with calculating the values you think you need, let us know the response you'd like to get. Are you sure you'll be ok lowering this since your BP sub may suffer overexcursion?

Lowering the knob-controlled low-pass crossover is possible I'm sure. I'll have to research on what needs to be changed, but I can do that if this is what you want to change.
 

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Thanks for your reply. It's lowering the knob frequency that I need. 40 Hz is too high for my setup--getting too much output at 40 to about 60 Hz or so. Ideally, I would keep the boost but lower the freq of the peak from 35 to 28 Hz, then drop-off at 24 db/octave above that.
 

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I think ideally, the best solution would be a steeper slope for the lpf. But that isn't likely to be possible. Honestly, I'd suggest finding a way to raise the crossover between your sub and mains. You may have too much bass in the 40-60Hz region because of the double-bass. Plus, I'm the type that recommends people not run their mains as 'large' (full-range) unless they can strongly reproduce all the way down to 20Hz. Lowering the lowest frequency of the lpf will result in your sub producing a very, very narrow band of frequencies, which I believe will really sound strange. But I'll look through some schematics and let you know if I find an easy way to accomplish this anyway.
 

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Yes, I understand what you're saying, I'd just rather not get into adding a crossover or HPF for my main speakers. This is a 2 channel music-only system so I have no electronic crossover, such as what is in most HT receivers or pre-processors.

With the main speakers only, I have a nice solid response down to 40 at the listening position. Using a RS sound level meter, I measure the same level at 40 as what I have at 120, with minor peaks and dips in between. Below 40 drops it off like a rock, mostly due to the room which is open to the whole house, and cheap single pane windows, etc, etc. I just want a bit lower response so I can hear (and feel) for example, the 30 Hz note on Pat Metheny - Secret Story, cut # 3 at about 3:50. My sub can do it, I already confirmed it, but then as I said, the response from 40 to about 60 is about 10 db higher than it should be with the sub on. Thanks!
 

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I recently purchased a "no boost" Yung SD 300 plate amp, prior to knowing about this forum or thread. I checked the reponse, as follows. The eq'd response I did with an external parametric as I needed to get this thing a bit flatter so that I could see what my speaker was doing.

2013-07-21_202635 plate amp2.png
 
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