NHB-108 Model Two circuit topology (using Zeels)

[all2ofme]

So, so happy with my NHB-18NS and Model Two into my Von Schweikerts. Great match.

Adding REL subs and need to check the circuit topology of the Model Two — am I right in thinking the Model Two is dual mono and single-ended, rather than fully balanced/differential?

Makes a difference to how I set up the subs apparently.

ETA: in case it’s important I’m using a long run of the Evolution Acoustics BNC Zeels and loving them.

Thanks so much for any help, dear WBF people!

Ben

 

[all2ofme]

Is that like a “yep, you’re right” @Hyperion? I like being right

 

[Mike Lavigne]

Is that like a “yep, you’re right” @Hyperion? I like being right

although i don't personally know the answer for 100% certain, without asking Herve, my strong guess is that my dart 468's and your 108 Model Two do not have true differentially balanced circuits.

 

[all2ofme]

That's my take too, Mike — fully differential circuits feel like the heavy-handed, component-laden antithesis to Hervé's circuit design ethic. Thank you for the help.

I'm sure the darTZeel team have been busy of late with the distribution changes (RIP Jonathan, and thank you for the cables ??) so I've not wanted to bother them unduly.

Before I do get in touch, if anyone else has an additional nod I'd be very grateful.

 

[Tabl10s]

Not fully balanced per Herve. Friend with dual REL's had to go single-ended to run sub's.

 

[Kingrex]

The older model one are not true balanced. You can see the shared signal wires through the top.
More current versions have a isolation transformer on the signal input. Not sure what the new model 2 have.

 

[Tabl10s]

The older model one are not true balanced. You can see the shared signal wires through the top.
More current versions have a isolation transformer on the signal input. Not sure what the new model 2 have.

.

 

[struts]

The older model one are not true balanced. You can see the shared signal wires through the top.
More current versions have a isolation transformer on the signal input. Not sure what the new model 2 have.

Actually, in the model two at least, the balanced input simply goes through a balun (I don't know which type, would need to open it up to see) as shown in this diagram penned by Hervé's own fair hand.



Pretty clear that the circuit is indeed completely single ended (@all2ofme), the zeel input is simply impedance matched and the XLR input is just tacked on.

This diagram also makes it abundantly clear why one should never have more than one input connected at once, the switch is just an impedance matcher, it does not switch the inputs!

 

[marty]

Seems like a nice opportunity....?

https://www.audiogon.com/listings/lisb7hgb-dartzeel-nhb-468-mono-block-amps-3-months-old-solid-state

 

[all2ofme]

/me checks down the back of the sofa