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Vandersteen 5A battery replacement

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My experience is that all caps (including small film caps) at zero volts sound better with two in series and a voltage higher than the signal applied between them.  Our amplifiers do not have damping networks because they are audible, IMO.  This is why they are mono blocks because they could get unstable with longer speaker wires (bad anyway for sound) better to use longer interconnects.  RV

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Great - thanks.

My experience through experimentation and simulation is that "Zobel" networks at the emitters of followers do pretty much nothing with regard to stability.  Sure, they prevent issues if there is no load attached.  That's a real thing, of course, but it's possible to manage that otherwise.  Once a load is attached, the issue really then is that lower impedance loads, as often found with highly capacitive loads,  are the problem.  Zobels at the output don't help with that. 

But...  (There's always a "but")  All these devices do end up with a negative input impedance at some frequency that's caused by the basics of the transistors.  If you don't deal with that, you will have varying results depending on the load and all the other variables.  You get actual voltage gain at some frequency, almost always way above the audio band, which is never a good thing with a follower.  That causes either peaking in the transient response or actual instability, if not oscillation.  So, you do need to address that situation.

I'll put in the added caps and the bias circuitry.

Thanks again.

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By installing the crossover into the amp, if (heaven forbid) one decides on a different speaker,  the amp has to be put "right".  My Ayre amp was at Ayre being repaired ...a fuse failed from checking for the proper impedance as per Richard's directions.  120 dollars twice for shipping to and fro .....Ayre said the amp is very stable and that I should use the published impedance for any frequency.   OK ....so I should not have monkeyed around with it .....maybe the fuse would have not blown.....anyway....the amp is on the way back to me......I'll soon be able to get back to listening. 

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20 hours ago, Richard Vandersteen said:

Stringreen, having the impedance wrong is a problem for the speaker but the amp could care less.  Check your wires for a short or something else or you could cause the amp to go down again.


What great support from a great manufacturer....When I told (Ray?) that my amp went down after he fixed the midrange, he called me back and had me take measurements of his work...of course it was fine, but it shows a very high level of support.  I just got R's concern as well, so I just checked for shorting in the XLR preamp to filter cable....the voltmeter gave me the appropriate buzz for the completed connection on all 3 paths of the XLR on both cables....but now, after Ayre told me one thing, it may be wrong (or misinterpreted?). I guess I have to check the values again...but boy am I shaking.  Let me begin....I burned a Vandertones CD from the website.  I connected the XLR cables from the preamp to the filters, and then to the amplifier.  The amp has 2 pair of speaker connections per side......I connected speaker wire to the Vandersteens.....the highs to be delivered from the front side of the amp output pair and the lows near the rear section of the amp on its left side......then connected the same for the right.  I attach the voltmeter black to - red to + between the spade of the speaker wire and the amp output connecter +and -.  The speakers will play, but I take the measurements of each of the 4 pair and turn off the amp between each reading.  ( I used to have something called a Webcor Holiday (the 50's) that played all size records at the needed speed and had a handle on it to carry to parties. played right out of the box.)


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  • 4 weeks later...
On 1/27/2022 at 9:36 PM, TomicTime said:

….yes..it’s very possible to change out the coupling capacitor for the appropriate value to create a high pass filter…..BUT…. those super high quality teflon caps take awhile to break in..AND unless a DBS voltage or similar high tube amp voltage is applied, they will lose form…. So unless the amp circuit itself keeps it formed in standby ( not likely ), the M5 will most likely sound better. RV and i just did an analysis of my tube amp and decided that the circuit would not keep the cap formed. The M5 filter is a better choice for me. YMMV. 


And you must determine that your V speakers are for ever...

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