[Nuge]

EC's sound different than A&S and DNA. If I were to put it to a spectrum, DNA would be on the laid-back, refined and grandiose presentation style with a good dose of wetness and mostly neutral tonality, A&S (at least the Mogwai/BB/Nautilus family) is more energetic, upfront, macro focused with creamy (that's different than DNA) mids with warmer leaning signature while ECs are very linear, little wetness in the signature, more neutral and very microdetail focused (texture). People at SBAF love all kind of sound signature based on my short experience with them and have strong preference as to what sound they like just like HF.

I just meant in overall quality, but yes, they did stress that the Aficionado and Kenzie Encore sound very different.

 

[JooLoo]

Finally finishing my ss amp 2ch system also the tube amp headphone system.

whats that stand your forge is sitting on?

 

[ampsandsound]

That’s a really good looking setup.

 

[theveterans]

@ampsandsound

Any info on the output impedance of the Forge 32/300 ohm taps? I'm just eyeballing that the 32 ohm tap is around 2-6 ohms while the 300 ohm is around 20 ohms? Just getting a rough idea of the damping factor for a 63 ohm headphone load and some of the power losses from having too low of damping factor

 

[shwnwllms]

@ampsandsound

Any info on the output impedance of the Forge 32/300 ohm taps? I'm just eyeballing that the 32 ohm tap is around 2-6 ohms while the 300 ohm is around 20 ohms? Just getting a rough idea of the damping factor for a 63 ohm headphone load and some of the power losses from having too low of damping factor

I could be way off but by my own calculations and research I’d put the 32 Ohm tap around 12 Ohm output and 300 Ohm tap at around 100 Ohm output. (This gets the desired 1:3 damping ratio for SET amps) I just went through this exercise myself for my Agartha the other day. This is also just an estimate for purely academic purposes and will obviously change with choice of tubes.

 

[theveterans]

I could be way off but by my own calculations and research I’d put the 32 Ohm tap around 12 Ohm output and 300 Ohm tap at around 100 Ohm output. (This gets the desired 1:3 damping ratio for SET amps) I just went through this exercise myself for my Agartha the other day. This is also just an estimate for purely academic purposes and will obviously change with choice of tubes.

That's crazy high even for OTL standards. This would mean there's a lot of power losses when driving inefficient low impedance planars like the Abyss and Susvara and DCA Stealth then

 

[shwnwllms]

That's crazy high even for OTL standards. This would mean there's a lot of power losses when driving inefficient low impedance planars like the Abyss and Susvara and DCA Stealth then

Couple of relevant posts:

https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/post-17450565

This one has deeper calculations showing a Mogwai SE 300 Ohm tap at about 100 Ohm output impedance

https://www.head-fi.org/threads/the-un-official-amp-thread-for-zmf-headphones.965309/post-17292382

Related to SET amp damping ratio

https://www.head-fi.org/threads/zmf-caldera-new-planar-magnetic-from-zmf.964836/post-17174224

Also doesn’t the Forge come in an 8/100 configuration (which is the recommended configuration for planars, and well as high sensitivity dynamics due to a lower noise floor)

 

[theveterans]

Wow excellent post! Thank you so much!

Based on rough calculation from Lord Gwyn's post: assuming that the Primary coil is 5000 ohms and Secondary coil is 32 ohms, I get 156.25 ratio. Then I looked at TAD KT66 and in tetrode mode (assuming that the load resistance in triode strapped mode is the same) is 2200 ohms. Therefore: 2200/156.25 = 14.08 ohms at the 32 ohm tap and 60 ohm / 14.08 gives me a 4.22 damping factor, not that far off from the 3:1 with SET amps

This is running the Susvara off KT66 tube with Forge: The mids from KT66 sounded better than KT88 for me with Susvara and I'm assuming it's about 3 watts or less with KT66 and 6SL7 driver tube at 32 ohms which is plenty for Susvara at normal listening levels

 

[ampsandsound]

Sorry for a late chime in but on I’m vacation currently. We don’t go into breakdown of how we load the output stage… That said, there’s lots of variables to be considered, pri impedance vs (selected output) sec impedance, tube choice and impedance of VC which is not constant. The Forge is currently sold out. We had 2 different versions optimized for various headphone pairings.

I will share one anecdotal point, I’ve nearly always selected very high primaries as a way lowering distortion and suppressing power output. I’ve never believed total power out was a key to anything but rather low distortion, low noise and wide bandwidth were.

Triode strapping tetriodes sounds better in general.

Tube choices I’ve never found to be well devised through calculations but rather listening, many times I’m surprised by pairings… additionally realizing the importance of burn in/break in on tubes.

The Forge is a monster of an amp… it’s great strength is its power supply.

 

[Scarydog]

Quick question . In the Nautilus, should I match the impedance of my headphones to the marked impedance on the outputs (at least as a starting point)?

Ie. 300 ohm cans to the high z. LCD 5s to the 11ohm?

 

[shwnwllms]

Quick question . In the Nautilus, should I match the impedance of my headphones to the marked impedance on the outputs (at least as a starting point)?

Ie. 300 ohm cans to the high z. LCD 5s to the 11ohm?

Correct. A&S taps represent the load (headphones you are plugging in) rather than actual output impedance like some amps do

 

[Scarydog]

Correct. A&S taps represent the load (headphones you are plugging in) rather than actual output impedance like some amps do

Awesome! Thanks!

 

[shwnwllms]

Tonight’s driver roll in the Agartha - MELZ 1579 (Mouse Ears). Incredible pairing with Elrog 300Bs & Caldera.

 

[Strayngs]

I will be putting the power capability of the Bigger Ben Rev 2 to the test soon. Have the incredibly power hungry Modhouse Tungsten DS on the way. I am really hoping it can do the job….other wise the Tungsten will hit the classifieds because I only have space for 2 amps and neither of my amps is negotiable. I also changed out my Canary C1300 preamp to a much cheaper Hattor “big” preamp…and I think the Hattor is such a better match with the Bigger Ben. I had noise issues…but no longer.

 

[theveterans]

Tungsten should be easier than Susvara from the BB since Tungsten requires more voltage and less current than Susvara based on specs alone. Tube amps are more comfortable with higher impedance load in general. Actually, DCA Expanse would be the hardest to drive with the BB due to its low impedance but at very high volumes, Susvara will be a lot harder than Expanse due to its much higher voltage requirement while maintaining gobs of current requirement at the same time thus translating to more overall power requirement.