Adam KRK mod

[pucho812]

:green: I finally got an uploaded pic. My buddys band is hosting it. cool.http://vasdeferens.net/ST6MOD.JPG

 

[petshoes]

Looks nice Puncho! Did you do any other mods besides replace the tweeter?

 

[pucho812]

No. I talked about this in another post just swipped the tweeter. It has opened up the sound alot and is definately making my mixes better. In the other post on speaker mods I mentioned the tweeter is only $81.00 american and can be found at
-www.speakercity.com

 

[mesmer]

Verry cool idea. I wonder if the mac_kie_hr824 would be cool to try these with? What has woofers closest to ada_ms?
Peter

 

[pucho812]

I went with the St-6 mainly because the ribbon tweeter fit the space available as well as it is a passive circuit so I wouldn't mess up anything to badly. PLus an St6 is only $99.00 American . I am sure your mackie would work awesome with it but I doubt it would fit.

 

[nacho459]

ADAMs have different woofers with different speakers. It's the tweeters that are the same in every speaker. They just came out with a passive box which I believe is the only box with a different tweeter. The regular tweeters have 4 magnets, the passives only have 2.

 

[Marik]

For tweeters ADAMs use Heil air motion transformers. Their principle of working and sound is very different from ribbon tweeters.

 

[tommypiper]

Is there a back panel you can remove on the ST6? Is there a way to look at the tweeter filtering?

I notice in the ribbon tweeter datasheet they recommend a crossover of 3k or higher, and the KRKs are 2.5k.

The next step in a mod would be to control the crossover and tweeter filtering, and perhaps upgrade the capacitors.

Is there a way to access the innards?

 

[Svart]

ribbon tweeter backwards = ribbon mic? :green:

 

[Svart]

uh what's the model/manufacturer for that ribbon tweeter? i can't seem to find it on that website..

uh it's on the front page... DUH

 

[pucho812]

tommy can you hear me? hahaha ust kidding.
Tommy, the way they build the thing there is no way access the crossovers to mod them. But the Ribbon can do down to 1.7K so I don't think there was an issue.

 

[Marik]

[quote author="Svart"]ribbon tweeter backwards = ribbon mic? :green:[/quote]

In principle, yes. In practice, would not work well--ribbon is 9um thick--way too much. Besides, this tweeter has its back enclosed=omni. Without stuffing it will ring.

But the Ribbon can do down to 1.7K so I don't think there was an issue.

Depends on which crossover order to use. If it is 2.5K first order, then there is a very good chance of damaging ribbon with low frequencies.

Original crossover point was designed for the stock tweeter. If the ribbon you use, has impedance any different from that, the crossover frequency will be screwed up, and it is a good idea, for the best results, to measure, recalculate, and rebuild it.
Also, if sensitivity of original tweeter is any different from the new one, tonal balance will not be right, and will need to be carefully matched. A few Ohm high watt pot before crossover cap will do.

Please, don't take it as a critisizing. I am sure even the mere tweeter (esp. ribbon) change will improve sound in many, even higher end speakers, but carefull calculation and matching of all parameters, can bring your speakers to completely different level of performance. In this respect, it would be also worthwhile to play with Q of the box, trying different stuffing.

 

[tommypiper]

Marik, thanks. You understood what I was saying. It would be very helpful to control, or at least diagnose, the crossover filtering within the speakers. Otherwise the tweeters may be damaged and you are probably not getting optimum results. Since these are budget speakers, I worry the crossover is low order and the tweeters may be damaged. Has anyone any experience with these types of speakers and their crossover circuits?

This would also offer an opportunity to further increase the speaker performance, as Marik and I were saying.

Here's what the datasheet says http://www.d-s-t.com.au/Data/Misc/JP30_WN_A4_NP.pdf
"Applied power to the ribbon should be limited by careful crossover design for your particular application as this ribbon has a built in transformer with a primary impedance 0.2 ohms DC!. This can in effect short circuit an amplifier below the frequencies of 200Hz. Thus a high order crossover is used. Also, because of the ribbons low mass diaphragm, they are susceptible to low frequency damage ...and are therefore best operated at frequencies above about 3Khz. ...recommends a 3rd order filter (18dB) between 3.7K to 9Khz."

"WARNING; If a simple 6dB/octave filter (single capacitor in series with the ribbon) is used below frequencies of 5Khz then low frequencies may damage the ribbon diaphragm!"

"For lower crossover frequencies in the range from 3KHz to 8KHz the ribbon requires a minimum of a 2nd order 12dB/oct or better a 3rd order 18db/octave high pass filter design."

 

[pucho812]

Marik, Tommy.
First off i would like to thank you for the information to be honest I am pretty good at the fix it game but new to the mod and build game. Orginally I picked the st6 because it fit the dimensions of the ribbon. After going over the specs and with my limited knowledge it all seemed good. as much as I would like to mod the crossover it's pretty much unaccessable. In the back of the speaker there is just banna plugs and no access to the crossover. In the front there there appears to be no way of accessing the crossover. At the moment it has been sounded real good and I have had it up pretty loud. I am pretty satisfied at the moment sonicly but as always my quest for knowledge has going am I F**KING SOMETHING UP?
I appriciate all the input from everyone on this list. always a lot to learn. have a happy turkey day.

 

[Marik]

as much as I would like to mod the crossover it's pretty much unaccessable. In the back of the speaker there is just banna plugs and no access to the crossover. In the front there there appears to be no way of accessing the crossover.

If somebody put this crossover inside, it means that there should be a way to take it out. Most likely you will need to take off the woofer.

At the moment it has been sounded real good and I have had it up pretty loud. I am pretty satisfied at the moment sonicly but as always my quest for knowledge has going am I F**KING SOMETHING UP?

Hard to say. If you are lucky, it might be fine. If not, some kick drum umpth can make your ribbon fly over your head at the best, or fry your amp at the worst.

Also, it is hard to say what the specs for the woofer are. If you raise crossover frequency, lets say to 3.5K, using 3rd order, then there is a chance that the woofer does not go that high. Without knowing all these things it is hard to suggest something specific.

Here is what I'd do, if I wanted to do it right. First, I'd change the woofer, as well, for something more serious. There are a lot choices here--Morel, Audax, Wifa, Scan-Speak, Peerless, Cabasse, etc., which could go as high as 8-10K. Then I'd do a first order, crossing at somewhere around 5K. If you want ultimate, then biamping would be a very good option, using electronic crossover. Many of them have continusly variable crossover points, so you could fine tune it for the best sound.

In any case, if you decide to keep it as it is, at least put a nice polypropilene cap instead of stock, most likely chipo electrolytic.