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Vandersteen 2Wq subwoofers with M5-HP crossovers - help needed

I have been happily using a pair of Vandy 2Wq subs with single-ended M5-HP crossovers for a few years now. My system was dialed in the way I like it (bass a bit on the full side, but still tight and defined). I just had my amplifier repaired and upgraded, and the new input impedance is 22k ohms vs. the 10k ohms before the upgrade. I followed the Vandersteen recommendation for the jumper settings in the M5-HP (6 and 7 only, "on" or not open), and the bass is just about MIA altogether. As per the Vandy web site, I disregarded the chart on the case of the M5-HP and followed the chart on the web site.  Because I am an idiot, I didn’t bother to mark down the settings of the jumpers prior to changing them. Anybody have any suggestions for me that will restore the bass? I am pretty sure the issue is the jumper settings. Thanks in advance!
bondmanp
bondmanp OP
1,821 posts
 
@mr_m - Thanks, that was helpful. Since my pre is tubed, our systems have a bit in common.  I think I am going ahead with the amp.  Hopefully, it will all work together.
gdnrbob
4,458 posts
 
I would do as Mr. V. said, and check to be sure the impedance is acceptable for the crossovers. 
The only other Agon'er I would contact would be Ralph Karsten (atmasphere). I am sure he would know if there will be issues with impedance. (And, I know he is working on a Class D amp, as well).
Bob
mr_m
1,900 posts
 
gdnrbob,

My Class D hybrid, is the Rogue Pharaoh. it has a 40k.input impedance, which is spot on. I talked to Richard V. about my amp and his biggest concern was if I had the proper pre in, power out connections. Which I have. His main concern for proper input impedance is not to overtax the subs internal amplifier with an incorrect crossover point. I'm not an electronics expert, but I tend to think that the only way the M-5 crossovers won't work with a given amplifier is if said amp had an input impedance outside of the M-5's capabilities for proper adjustment.

I will say I'm a bit surprised about RV's questioning of a manufacturer's specified input impedance not being as stated, specifically class D, as he never once mentioned this to me considering the multiple phone conversations we had. I also talked to Rogue's electronic engineer at length about pairing their amp and Vandersteen's crossovers and subs and he found no fault with this setup either.

Ralph Karsten is a fine designer, but the guy's at Rogue are no slouches either and have been working with Class D for quite some time. I trust their judgement as the proof is in the pudding as far as my system is concerned.
audioconnection
1,271 posts
 
(((I will say I’m a bit surprised about RV’s questioning of a manufacturer’s specified input impedance not being as stated, )))
It’s not about trust or questioning or what the input impedance spec in the owners manual reads.Its what the voltmeter reads plain and simple.
The reason this is misunderstood is some amps have
J fet drivers some bipolars which measure slightly different at 1000 vs100 hz or 80 hz
((The absolute only way is to confirm is with an AC Volt meter not an owners manual))
Install red and black voltmeter probes in amp speaker binding posts turn down volume in pre amp play Vandertones CD track 27 1000 hz with Voltmeter set to AC millivolts adjust pre-amp volume slowly up till it reads 1V AC then play track 30 for 100 hz Vandy five, seven, Quatros, etc or track 31 for 80 hz Vandy 2W 2WQ or new Sub 3 if your xover dip switches are set properly or installed at amp factory it should read .707 If not start from the begining adjust dip switches untill you have it set properly.I also think you are fine with the Rogue Pharaoh if you confirm above or your amp was done at Rogue and measured as above.
Best,JohnnyR,Vandersteen Dealer

gdnrbob
4,458 posts
 
Well, there ya' go...
B
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