Massdrop Cavalli Tube Hybrid Amp

Those with more experience with designing LPS's than me, please correct me if I'm wrong.

28V @ 1.25 A means a transformer that is rated for at least 30 V (if you want to design on the edge) to 36 V with >=2.5 A continuous. So, at least a 100 VA part with correct secondary voltage. optimally 24 Vrms and at least 80 VA (100 VA would be better for better regulation). EDIT: Thanks @Cspirou for correcting my error!

A voltage regulator that has a Vout-max >=33V and can handle 3A

Be very careful of the mains going into the transformer. You do so at your own risk as electricity from the wall can be dangerous.

Read the application notes on the regulator for how to make a suitable circuit. Adjust the bulk and filter capacitance to your liking. Add in a suitable bridge rectifier (>3.5 A). Slap a heatsink on the voltage regulator and maybe the rectifier if you are close to the amp rating. You probably should add an in-rush current limiter (an appropriate NTC thermistor) and a slow-blow fuse as a partial safety measures to protect this ~$100 DIY project.

More advanced designs should include EMI filtering or by adding a power entry module that includes a plug, an on/off switch, EMI filtering and a fuse.

Happy building!

 

If I get this it'll be mainly for HD650Ms and Slants, but has anyone tried these with Andros using an iEMatch? Someone said they enjoyed the Vali 2 that way.

 

Cavalli is typing golden nuggets at Massdrop. Rather than mirror them here and having to update the post as he replies, just look at his post page:

https://www.massdrop.com/profile/AlexCavalli/comments

 

Words like mini crimson make this a no brainer for me. 249.00 for a cavalli amp is ridiculous.

 

I agree and disagree here. Many people said the same thing about LC. But IMO it didn't turn out to be a mini Cavalli anything. There were production problems with that amp, especially the potentiometer. Lot's of delays also.

The only Cavalli that has blown my mind is the Liquid Glass. That amp is insanely good with everything headphone I've paired with it. Almost bought on here a few weeks ago. I couldn't quite raise the funds though. Still sad about that.

Point being, I'm not ready to call this amp a mini Cavalli xx until it's out in the wild and the community beats on it good and hard. Then we can look at potential monikers.

 

Those transformer voltages are peak voltage, right? Transformers are usually Vrms which means your 30V to 36V range translates to 21V to 26V.

 

From alex. I thought this was interesting.

Some of our testers have noted that tube rolling doesn't make that much difference and that's because there is a small amount of global negative feedback and this feedback tends to make the tubes sound less different.

 

Sorry, complete noob here when it comes to audio equipment. I currently have some DT990 pros (250ohm) coupled with a Xonar Essence STX sound card (I know an integrated card is a big no no when it comes to audio, but it has served its purpose when it comes to gaming). I have purchased a pair of 6XX's that should get here in December (so shipping time isn't an issue). My question is, would you recommend a BHC (without speed ball) or this amp? I don't have any issues with the construction part of the BHC.

 

Yes, the values I listed should be in VAC or Vrms as I was referring to the output voltages from a secondary winding. 36 Vrms would be a smarter choice due to the >2 Vdrop that will occur between the transformer and the regulator (filter components, thermistor, bridge rectifier, etc).

 

search this thread for 'crack'. At least two people who have reviewed this amp have commented on the crack.

 

I've read through the whole thread. I was just wondering which they would recommend if they had to choose one.

 

36 Vrms is way too big. The peaks are 52V, which after some rectification and capacitor smoothing would probably be 48V unregulated. That's a 20V drop to get to 28V DC and would require some major heat dissipation from whatever regulator you are using.

 

If you want to tube roll to fine tune the sound, get the crack. It's also fun to build, and fun to enhance.

If you want an out of the box, ready to use amp, get the Vali or the the CTH. You can tube roll to an extent on the Vali, but tube rolling on the CTH will likely not produce that big of a change.

 

I stand corrected. A 24 Vrms transformer with at least 80 VA would be a much better choice. With a regulation of 0%, you should get a couple volts to spare. With 10% regulation, you have about 0.5 VDC to spare.

 

Holy heavens yes! EHHA with choke filtered LPS, or shunt LPS and low global feedback is what a hybrid needs to be.
The World needs it, not reserved for diy nutters only.

 

Estimated ship date is Feb 27, 2018 ...