[audioguru1]

Continued progress. Decided to go old school and just cut a round hole for the display. Did some polishing and put polarizing film. Next up is the top which I think i'm going to cut circles and do mesh behind. My next project I want to do a fully CNC front, but i'm pretty happy with the result so far.

 

[slumberman]

Continued progress. Decided to go old school and just cut a round hole for the display. Did some polishing and put polarizing film. Next up is the top which I think i'm going to cut circles and do mesh behind. My next project I want to do a fully CNC front, but i'm pretty happy with the result so far.

very nice!

 

[Satyrnine]

So when considering a preamp in front, the real question is how much voltage does the CFA3 circuit handle before distorting. I recently had a different amp on the bench that distorted at anymore more than 2.1v of input.

Your build looks amazing! For what it's worth, my 30v dual mono CFA3 Tube Hybrid was able to hit around 2.5v of input before distorting. (2x grlv@30v(100VA each) > 4x CFA2 boards + 2x of Kevin's "ubal2baltube" tube input boards (also at 30v). 1x grhv100/6.3 power supply and matching toroidy 90v/8v transformer.) I used Siemens E288CC tubes which have a slightly higher heater and plate current vs a 6922, and are 1/2" taller.

Note that that was measured with an old techtronix tube scope and basic fluke meter, nothing fancy.

 

[Satyrnine]

Can I get away with this method of heatsinking for the grlvs? I plan on running 8ohm speaker loads. I admittedly have only tested with 50-600ohm headphone loads, but the small sinks I had on the grlv's barely got warm at all. Maybe 105*F max. I have 100VA 30v transformers. I seem to recall someone mentioning that 100VA and the low overhead 30vac secondaries mean less regulator heat from the grlvs? Below is what I was thinking of doing. I could also rotate them 90* left, bolting the L bracket to the side plate but that's even thinner steel than the bottom plate, and would move the DC outputs closer to the 90vac input on the grhv to it's right. I could also rotate the grlv 180* and remote mount the regs to the ~1.5mm aluminum back plate, but that would bring the grlv 30vac inputs closer to the DC jacks as well.



Second, here's what I can get away with for IEC - grhv proximity. Think it will be a problem?





It would give me enough room for the (admittedly too "deep" but fantastic looking and heavy duty power switch at the top, plus room for distribution blocks for mains/grounds.



Big thanks to anyone willing to share their wisdom.

 

[audioguru1]

Can I get away with this method of heatsinking for the grlvs? I plan on running 8ohm speaker loads. I admittedly have only tested with 50-600ohm headphone loads, but the small sinks I had on the grlv's barely got warm at all. Maybe 105*F max. I have 100VA 30v transformers. I seem to recall someone mentioning that 100VA and the low overhead 30vac secondaries mean less regulator heat from the grlvs? Below is what I was thinking of doing. I could also rotate them 90* left, bolting the L bracket to the side plate but that's even thinner steel than the bottom plate, and would move the DC outputs closer to the 90vac input on the grhv to it's right. I could also rotate the grlv 180* and remote mount the regs to the ~1.5mm aluminum back plate, but that would bring the grlv 30vac inputs closer to the DC jacks as well.



Second, here's what I can get away with for IEC - grhv proximity. Think it will be a problem?





It would give me enough room for the (admittedly too "deep" but fantastic looking and heavy duty power switch at the top, plus room for distribution blocks for mains/grounds.



Big thanks to anyone willing to share their wisdom.

It’s probably fine, it would be more ideal to heatsink to the outside of the case but if the temps are fine it’s fine. I would pay attention with the top on it how much ambient temp is inside. That’s probably the biggest risk. Since the PS is separate from the audio section I really don’t think placement is so critical.

 

[Satyrnine]

It’s probably fine, it would be more ideal to heatsink to the outside of the case but if the temps are fine it’s fine. I would pay attention with the top on it how much ambient temp is inside. That’s probably the biggest risk. Since the PS is separate from the audio section I really don’t think placement is so critical.

Great, thank you! I’ll see what I can do about mounting to side panel.

 

[rsbrsvp]

@normie610,

What ever happened with your new CFA-3 super power amp?

 

[normie610]

@normie610,

What ever happened with your new CFA-3 super power amp?

There was some damage to the PSU, so it got sent back to Dukei together with my old CFA3 (which got damaged as well). Still thinking whether I would swap my CFA3 with an estat amp to drive my CRBN instead since the Primavera is doing such an excellent job driving my non-estat headphones.

 

[all2ofme]

Sorry to hear that, Normie. We all worry about that happening, but mostly we seem to get lucky. Commiserations that your precious beast caught the damage. (To Dukei too!)

Hope it leads somewhere good for you both.

 

[rsbrsvp]

There was some damage to the PSU, so it got sent back to Dukei together with my old CFA3 (which got damaged as well). Still thinking whether I would swap my CFA3 with an estat amp to drive my CRBN instead since the Primavera is doing such an excellent job driving my non-estat headphones.

Also sorry to hear about your difficulties. Many say The Primavera is indeed the last word in headphone amplifiers for non electrostats. I did hear that the tubes are a problem to get for it. Is that true?

 

[rsbrsvp]

@normie610 ,

The Primavera must be a very different experience than the CFA-3.... Can you share your thoughts..

 

[normie610]

Sorry to hear that, Normie. We all worry about that happening, but mostly we seem to get lucky. Commiserations that your precious beast caught the damage. (To Dukei too!)

Hope it leads somewhere good for you both.

Thanks! These things happen, and Dukei is such a good guy so hopefully everything will be okay.

Also sorry to hear about your difficulties. Many say The Primavera is indeed the last word in headphone amplifiers for non electrostats. I did hear that the tubes are a problem to get for it. Is that true?

AFAIK, Svetlana is still producing the SV572-10, which is the replacement tube for SV811-10. As for the driver tube, there’s plenty of supply.

@normie610 ,

The Primavera must be a very different experience than the CFA-3.... Can you share your thoughts..

Actually not too different, as the Primavera is probably one of the most resolving tube amps and it’s also highly musical with lots of power and control over the drivers. In some cases, I can get a bit more sub-bass quantity with Primavera (this is especially true with Valkyria). With regards to soundstage, CFA3 is more spherical in shape, whereas Primavera is still expansive but a bit flatter. Both are sweet sounding but since my CFA3 has speaker outputs, I can use it to drive the CRBN.

 

[rsbrsvp]

normie610, do you have any conclusion if for headphone use, the CFA-3P was any better than the CFA3 regular?

 

[normie610]

normie610, do you have any conclusion if for headphone use, the CFA-3P was any better than the CFA3 regular?

I’m afraid I haven’t had the chance to listen to it

 

[rsbrsvp]

I moved from the CFA3 to the Mass Kobo 394 II. IMHO- to my tastes; a fuller bodied, more textured, ultra transparent sound which I prefer.- I am happy with the move. Amazing how 2.2 watts can control the drivers as well (or better) than 16 watts. I guess it is all in the design. I did enjoy my days with the CFA3, but the MK is both more musical to my ears and even more technical. The nice thing ablot the CFA3 is how uncolored it is and how well it takes to a preamp. Although the MK does as well.