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adjusting x-over

Posted: Wed Mar 22, 2017 7:03 pm
by Rich4349
I picked up some Ashly FTX-2001 amps. They have a factory set crossover point of 750hz, that I want to change to 100 and have them be more ready to go out of the box. I have instructions from Ashly to swap out the resistor arrays inside, using parts from Digikey. Only one of the three possible choices is available from them, though, unless I want to buy 2000 of them. The choices are:

100 kohm = 113 hz (available singly)
110 kohm = 103 hz (out of production)
120 kohm = 94 hz (sold in units of 2,000)

The only one available in normal consumer quantities is the 100k, but I'd rather set the point closer to 100. Is 113 that bad? Does anyone know of other parts sources for resistor arrays in quantities of less than a googoolplex?


http://www.digikey.com/products/en/resi ... ageSize=25

Re: adjusting x-over

Posted: Wed Mar 22, 2017 7:12 pm
by jimbo7
Try Mouser.

P.S. I hate buying crossover parts from P.E., but it's so convenient when you make a large order.

Re: adjusting x-over

Posted: Wed Mar 22, 2017 10:18 pm
by J_Dunavin
http://www.newark.com/bourns/4608x-102- ... dp/32K9935

Not sure the number of elements you need.... You know, you could just make your own with fixed metal film resistors, on a small piece of proto board.
Not pretty, buy it would work and get the exact freq you want.

Re: adjusting x-over

Posted: Thu Mar 23, 2017 11:38 am
by Mkulu
Rich4349 wrote:I picked up some Ashly FTX-2001 amps. They have a factory set crossover point of 750hz, that I want to change to 100 and have them be more ready to go out of the box. I have instructions from Ashly to swap out the resistor arrays inside, using parts from Digikey. Only one of the three possible choices is available from them, though, unless I want to buy 2000 of them. The choices are:

100 kohm = 113 hz (available singly)
110 kohm = 103 hz (out of production)
120 kohm = 94 hz (sold in units of 2,000)

The only one available in normal consumer quantities is the 100k, but I'd rather set the point closer to 100. Is 113 that bad? Does anyone know of other parts sources for resistor arrays in quantities of less than a googoolplex?


http://www.digikey.com/products/en/resi ... ageSize=25
Try Parts Express, if they don't have they will tell you where you can get them in small quantities.

Re: adjusting x-over

Posted: Thu Mar 23, 2017 1:08 pm
by dswpro
You could also look for a higher wattage resistor at Digi_key to see if they carry those in smaller quantities.
If you were searching for 1/4 watt, look for 1/2 watt. Also try higher precision. If you were looking at 5% try 1%.
Just a thought.

Re: adjusting x-over

Posted: Thu Mar 23, 2017 1:47 pm
by David Raehn
Try Tayda. They're overseas but their standard shipping will put it at your door in a couple of days.

Post an example of the arrays. I might have some in my own stock.

Re: adjusting x-over

Posted: Thu Mar 23, 2017 3:31 pm
by billkatz
Rich4349 wrote:I picked up some Ashly FTX-2001 amps. They have a factory set crossover point of 750hz, that I want to change to 100 and have them be more ready to go out of the box. I have instructions from Ashly to swap out the resistor arrays inside, using parts from Digikey. Only one of the three possible choices is available from them, though, unless I want to buy 2000 of them. The choices are:

100 kohm = 113 hz (available singly)
110 kohm = 103 hz (out of production)
120 kohm = 94 hz (sold in units of 2,000)

The only one available in normal consumer quantities is the 100k, but I'd rather set the point closer to 100. Is 113 that bad? Does anyone know of other parts sources for resistor arrays in quantities of less than a googoolplex?


http://www.digikey.com/products/en/resi ... ageSize=25
You don't need that fancy isolated SIP - you could use 4 generic 1/4W axial lead resistors.

Re: adjusting x-over

Posted: Thu Mar 23, 2017 7:12 pm
by CoronaOperator
With DSP's almost a necessity is it worth the bother to use the built in one's?

Re: adjusting x-over

Posted: Thu Mar 23, 2017 7:58 pm
by David Raehn

Re: adjusting x-over

Posted: Fri Mar 24, 2017 10:44 am
by Rich4349
Thanks all, found some and they're on the way.

(And to answer the "why not just use DSP? question: I may very well just use one of the amps in the house where I won't be pushing my speakers even 1/10th as hard as PA.)

Re: adjusting x-over

Posted: Mon Sep 11, 2017 8:47 pm
by subharmonic
Why not use a DSP. The FTX have a modular input board: 2 or 3 way x-over, comp/limiter, mixer, or regular 2 channel input with gain. Most out there that I have seen have a 2 channel cross, which make it a 1 channel input. This is great for guys like us to skip passive crossovers in place of a dollars worth of resistors. I also talked to Ashly as I bought 6 of these amps. They recommended to just bypass the board and go straight into the input section for 2 channel use when the crossover is installed, citing no real need for gain control if you can control the levels elsewhere. Also a 2.2 k resistor in line with the fan makes these bad boys whisper quiet for home use.

Why resurrect this post? Because I regularly see these floating around ebay $120-175 each and they sound incredible IMO, I put them against a Marantz 8001, Crown XTI, Behringer A500, Behringer 1500, Sonitec 650, and Ashly KLR2000. The difference is there. Not saying it is the Mosfet or whayever but the sound was noticeably superior. They basically sounds less harsh, more detailed and full, almost liquidy for lack of a better term.

We are using 2 of them in our church to run DR250s and T39s. With the built in xover you can run 1 channel full range, 1hi/1low or both low. Works great for sub duty.

The FET and CFT series amps are in the same class I also have a FET 1500 running my mains in my media room.

Lastly be careful about the sellers, most seem to have gotten these as lots from old cinemas so at least they were installed and ran properly, if not ran a lot. However the ones I ordered for the church were mismatched (1 regular input and the other 750hz xover) and the seller would not send the regular input card, but as we run active. I have tried to buy/swap cards from sellers of lots and most have no clue until I ask, then those always seem to be sold first. Also make sure to ask how they are packaging, i have had issues with pro gear being sent with air bladders that get popped during shipping and stuff slides around then, so far only 1 item had to go in for repair but I nail sellers for carelessness.

Hope this helps someone that may be looking to up their residential system game on the cheap. BTW paired 2 of these on some TLAH through a Spatial Coherence TVA1 for some serious 2 channel listening, 3D sound is amazing in the right recordings.