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DM K-2OX OUTPUT/FREQ PLOT

Started by benzer, September 28, 2007, 12:30:23 PM

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joecool85

I can't get you a whole schematic other than the one on deanmarkley.com, but I can (hopefully) help you out correcting anything wrong on it by looking at my amp.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

benzer

no problem ,the most important values to check is C12,C24.
C2 AND R4 also if you can locate em.
and how much voltage does the transformer outputs

by the way,,is it that higher freq signals are louder than others? do u notice somthin like that? or maybe distorted?
Good OL' BeN

joecool85

Nope, it seems to amplify low and high end equally.  Also almost no distortion when loud on clean, I cranked it today and it was nice.  A little crunchy when really loud, but not too much distortion, it sounds great.

I probably won't be taking it apart today if that's alright, but soon hopefully.  Try to make a detailed list of what you want to know.  I can check values and take pictures.  I don't mind helping someone out, especially with the K-20X, I love this little amp :-)
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

benzer

thanks a lot for the information and the offer, i dont know how to thank you ... :)

taking pictures is just GREAT  :tu:
the values i want to know are :
C12
C24
C2
R4
R10
R13
AND THE TRANSFORMER OUTPUT VOLTAGE

thats all for now,,lol
im realy gratefuLLLL
Good OL' BeN

joecool85

No problem, I'll try to do it tomorrow.  I've had the amp apart before, it only takes like 2 minutes max to take apart.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

benzer

Good OL' BeN

joecool85

I thought I'd let you know I won't be doing it today as I have a huge test to study for.  I'll try to get to it as soon as possible.  Sorry to keep you waiting.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

benzer

nevermind man its ok...ill just hold on
hope you do fine in your test, go get em ,,,lol
Good OL' BeN

joecool85

Quote from: benzer on October 01, 2007, 02:14:45 PM
thanks a lot for the information and the offer, i dont know how to thank you ... :)

taking pictures is just GREAT  :tu:
the values i want to know are :
C12
C24
C2
R4
R10
R13
AND THE TRANSFORMER OUTPUT VOLTAGE

thats all for now,,lol
im realy gratefuLLLL

C12 - 1uF/50v
C24 - 1000uF/25v
C2 - 150p
R4 - 47k
R10 - 3.3k
R13 - 68k
Transformer voltage = 13.94v + 13.94v (running on 122.8v AC)

Looks like the schematic was right afterall.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

joecool85

#24
Also looks like the amp over voltages the TDA2030.  It is suppose to get +/- 18v and its getting more like +/- 19.5v (13.94 x 1.4).



Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

benzer

thanks man, realy awesome shots
i just wonder how an amp would sound GREAT with such freq response.,,
ill try to build this one as it is , and then change with some values n see how does this affect the sound
thanks again for openin the amp :),,owe ya
Good OL' BeN

teemuk

Nice photos. Seems like K-30RX and K-20X share the same PC board and chassis. Have you considered building that reverb circuit?

teemuk

Quote from: benzer on October 06, 2007, 03:32:15 PM
i just wonder how an amp would sound GREAT with such freq response.,,

It's really not that weird and a huge part in creating such a non-linear response is the tone control circuitry, which is similar to that of about 90 % of modern amps. I think the bass response is a bit lacking when compared to similar amps but then again, they might have compensated that with a speaker choice.

...And speaking about that: Typical guitar speakers are "mid-range" drivers and therefore introduce a very efficient low pass filter. That means they cut frequencies above 3 - 5 kHz a lot. Consequently, the treble will not be as enhanced as it looks in the plots.

The inherent low pass filter is quite beneficial in "smoothing out" the harshness of a distorted guitar signal. This is one of the reasons why small speakers or setups including tweeters, horns etc. tend to sound horrible. They are beneficial in acoustic guitar amplification, though.The low pass filter is also the key element in every "cabinet simulator" circuit.



When it comes to excursion and frequency response, typical guitar speakers are extremely unlinear devices.

joecool85

Quote from: teemuk on October 06, 2007, 04:07:20 PM
Nice photos. Seems like K-30RX and K-20X share the same PC board and chassis. Have you considered building that reverb circuit?

The K-30X is the exact same except with reverb, I noticed this about a year ago.  I thought about adding the reverb circuit into mine, but I don't know if I'll bother.  I don't remember it being that great anyway.

And Benzer, I think a good deal of the sound comes from the speaker choice as teemuk mentioned.  The stock 8" Dean Markley sounds alright, but when I hooked it up to my Dean Markley 10" cab it rips, I love it.  The biggest thing missing when running the 8" speaker is bass, but what do you expect from an 8" ?

Also keep in mind that everyone has a different idea of what "perfect" tone is.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

benzer

well yea thats right the lowpass filter cuts up the high gain provided for high freqs but i actually did model a speaker when i did my simulation using spice, or is it the lowpass filter of the speaker should be modeled too?

QuoteAlso keep in mind that everyone has a different idea of what "perfect" tone is.
True but i just noticed that the bass area needs a little more gain,,
isnt it just hot when u play bass notes to amply em up? ;D
anyways thats just a taste.

and yea about the speaker stuff, do u guys have in mind a speaker that i can buy and would be good for this amp?
i actually dont have much info about guitar speakers and cabs
should i get a speaker in a cab?
or can i just have em seperatley?

and yeah adding that reverb stack can be very usefull to play country music solos,,
Good OL' BeN