audio-talk

Do I actually need two of the 680R to ground You don't need them. You never needed them, only if you wanted the volume to be lower than 10k into the power amp input resistance would give. If i disconnect one of the 680R will it change the volume Yes, however the volume of two summed signals is more...

ed wrote: ↑Tue Sep 08, 2020 1:20 pm

I won't ask about the disadvantages of mono .....just yet

in the land of mono the one eared man is king(or woman, queen)

Thanks Nick.

I will connect the two channels after the 10K series resistors at the junction with the 680R to ground. Do I actually need two of the 680R to ground ?

If i disconnect one of the 680R will it change the volume ?

Just had a thought. :bom: Could I not just use the 10K resistors I already have in series with the signal and join the two channels after those ? I assume the variable resistance to ground after this junction just does it's potential dividing job and controls volume as usual ? If i can do it like th...

Hi Nick. Thanks for replying. My preamp (at the moment) is just a couple of resistors wired up as a potential divider in shunt configuration with 10k in series with signal and 680R to ground. It will eventually be a 10K shunt stepped attenuator (same thing essentially) or volume pot as per nva pream...

I would greatly appreciate some advice on this and please excuse my limited understanding. I was thinking about having only one speaker (omni directional) and listening in mono, well actually both right and left channels summed into one speaker. I can only think of two ways to do this and don't know...

Hello. I would be very careful when swapping parts on the nva amplifier boards unless you really know how it operates. Resistor swaps may not be too risky but capacitors are another story. I think Richard had this circuit optimised so becareful you don't make the sound worse. One modification at a t...

Hello. I think NVA input impedance is about 47 K ohms. Richard Dunn was not a fan of regulators or optocouplers. I have run regulators on the input stages of my nva amps but only because I needed to drop some voltage. I never got to try the input stage without as that would need different transforme...

Yes there are lots of different part numbers. If you can find the part number online that would be ideal. I looked on b&wsupport in usa but their site is down. Drivers do come up on ebay but they are usually taking the piss with the pricing.

Good luck with your quest.

You need to put a multimeter in the speaker outlets on the back of the amp and measure dc Should be below about 50 mA. B&W are no longer the company they used to be. I think they were bought out by money worshippers. I don't think they will still have drivers for these speakers which are probabl...

I’d like to put three power supplies on it, but I’m not going to do that. I reckon I’ve got away with what I’ve done so far, by the skin of my teeth, and these boards are precious to me. As far as I am aware, only myself and Stu have had them as bare circuit boards, to be DIY powered; so in that se...

I’m well impressed with the sound quality improvement over the A20. Multiple power supplies are in. :) I have heard a couple of reports of preferring the sound of a single psu. I am firmly with you on this one :D As there is no pot to change the bias then there is no inclination to bias it more in ...

Sorry, my terminology has been bad. Send & return, positive and negative are just incorrect terms you pick up on the web and labelling on the back of amps. Hi Ed. Yes those are the ones. I don't use them anymore (replaced by NVA LS6). Just looked back at the posts on PFM from over a decade ago a...

Paul Barker wrote: ↑Wed Sep 25, 2019 5:02 pm There is no send and return there is a waveform equally reliant on both cables’ quality.

Thanks for the reply and putting that little notion to bed Coax speaker cables are obviously different though in the positive and negative (my Avondale blacklink is coax.

Cheers, Stu

Hello, I had a thought today about speaker cables. Is the quality of the send (positive) wiring more important than the return (negative) wiring? Or are they both equally important ? Say you used a very high quality send cable and a much cheaper return cable (this assumes send and return are separat...