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What are the details on your sub?
My "sub" is a cobbled up thing - it's a Kef Concerto enclosure (BR with about 50 litres (1.8 cu ft)) with two B139 drivers back-to-back in isobaric instead of the usual one driver. I needed to check the tuning - glad I did as the port extension I had added was way to long as it turned out. The -3 dB point is about 28 Hz, which is not a big advantage over my main speakers actually.
The response above is for the amp, measured into a resistor.
I wasn't game to use REW for this as I didn't want to connect the SD 300 output into my brand new sound card, since the speaker voltage is sitting at half mains supply - so 120 volts AC above earth here in Aus.
 

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A little OT:

I've been searching and as yet haven't found the process for testing the actual response of the AMP using REW or by other methods as described above.

I have modified a Jaycar AA0508 plate amp for a friends 2.1 channel setup using the Critical Q Sub page. I did some A/B REW sweeps and did notice a difference, but i'd like to be able to verify the changes and perhaps lower the HPF as he's using a Sealed 12" Shiva and wants some more low end extension without having so much boost in the BFD @ 20Hz.
 

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I simply connected the soundcard output to the amp's preamp input. I have a probe with an RCA termination that I used to monitor the preamp output signal. This signal is usually easy to locate, as it's a shielded wire. It helps if you have a schematic, or maybe you can see labels on the pcb. Connectors on the preamp usually just have gnd, +/- voltages, amp turn-on, and the preamp audio signal. So once I locate the post-processed audio preamp signal, I put REW in 'calibrate levels' mode. After that, just run a sweep and see what your preamp's fr response is. Hope this helps.
 

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Knocked off work a little early today, had some time to play around, and i'm very glad i did. Found that the crossover settings on the control seemed really inaccurate and that no subsonic filter adjustment is necessary. Just probably needs a bigger box for more low end response.

Crossover frequencies were 40 (min),80,120,160,240(max)

Subsonic filtering doesn't seem to kick in until ~13hz.

Thanks once again.

Just confirming, this isn't for the Yung plate amp so yeh its off topic, this is for an old Jaycar AA-0508 350W plate amp which is similar to an old PE amp. Just always like to update/give a conclusion and thanks when i get some assistance.
 

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Pardon me, I am new to this forum and as a total lay person in regards to amp mods I come in search of aid. Recently I had been tinkering my Yung SD300 and was rather disappointed in it's frequency response below 30hz with 4 TST clark 209 tactile transducers hooked in series parallel. As such I have to come here in search of instructions/advice as to how I would be able to defeat the high pass and set it to more favorable 15-10hz cutoff. Also reading through the thread it seems apparent that there is bass boost in the mid 30hz region on all yung amps, being able to defeat that bump for a smoother response would also be preferable. I realize that this information has already been made known in this thread, but being the lay person that I am, the language of the instructions provided was alien to me. If anyone would be in a mood courteous enough to provide a more pedantic/manageable version of instructions I would be infinitely grateful :innocent: .
 

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Hi,

I'm a new member, from Italy. :)

In my country i've found these plate amps with another name and brand, but they look exactly the same.

Monacor sam300d, this is the model that I would buy. The 500 watt version is not sold here :(

I've read all this thread and thanks bgarcia17 for the great work you've done.

I've a question about defeating the high-pass filter and the boost:

Using a bfd1124 (i've one) it's possible to boost the 20-25 hz zone and cut the 35hz boost zone to achieve a flat response without change the resistors? It's a good idea or it's better the resistors mod?
I just need a flat response down to 20hz.

Thanks!

Sorry for my English!
 

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It's really a personal choice. If you are comfortable with soldering, I'd recommend the amp mod to avoid having to boost too much with the external EQ. If not, certainly give it a try with the EQ and see if you are happy with the results. I prefer to minimize EQ, and I prefer that the amp have flat FR...but that's just me. :)
 

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Thanks for the quick reply!

If i need to set the hpf to 18hz (for example) i need an smd resistor of 28 kiloohm and one of 56 kiloohm, correct?

about the package? 0805?

Can i use any other type of resistors (with same ohm value) or it's reccomended only smd resistors?

I think that i will set hpf between 15-18hz. Do you know how can i calculate resistors values for 15hz?
 

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Calculator says 34kohms and 68kohms for 15hz. In caps value i wrote 0.22 µf, correct?

I'll try to find smd resistors. If i'll not find them, i will use more common axial resistors.

About power rating and tolerance of resistors? i need some particular values?
 

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Just to re-open this thread with a dumb question. I'm building a Stereo Integrity HT18 D2 sub in a 4 cf sealed design. Want to do a plate amp to keep things simple. Yung SD500 with or without boost? This is 50/50 HT to music. No interest in modding anything...just wondering which way would be best in this sealed setup.
 

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Just to re-open this thread with a dumb question. I'm building a Stereo Integrity HT18 D2 sub in a 4 cf sealed design. Want to do a plate amp to keep things simple. Yung SD500 with or without boost? This is 50/50 HT to music. No interest in modding anything...just wondering which way would be best in this sealed setup.
With the boost would be best.
Agreed, the +6dB @ 25Hz would work really well for a sealed sub and the SI 18 should have the travel to do it safely.
 

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Hi, did any one have schematic of young sd500 plate amplifier? Me amplifier dont work, servise cant help coz no one have schematic and some parts are name earesed. Please help me!
 

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Hello everyone.
I don't know if this thread has stopped but I'll try to ask anyway.
I have read that others have had my current problem with the "Yung sd300".
And that is that this electronics has a minimum high pass (40hz) too high. I would like to use my sub on a 2.1 system and it shouldn't work above 30hz (better yet 28hz).
I do not have the possibility to modify the resistors, but i changed the capacitors to move the boost peak back ..
as shown here :

At this point I wondered if there is a way to lower the high pass cut. I ask the greats of this thread, "bgarcia17" and "monomer":
Would it be possible to obtain this by intervening on the potentiometer?
We know that turning all the way to the left we get 40hz.
I am not a professional technician, but if in that position you have the maximum or minimum resistive value (I think 22k), perhaps with 25 or 30, things would change in the high pass.
Is there any way to calculate it?

Thanks in advance to anyone who will answer.
 
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