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Swordfishy/ASPEN FETZILLA power amp

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#842
Well it's been powered up now for about 30 hours - about 6 hours of music. Listening now and there are no warts is far - response across the frequency range seems even - nice detail without being bright. Possibly slightly laid back (warm) presentation but it's very easy to listen to - and it's got good punch for a 50 watter. I think this may become my favorite. I think Hugh is right on the money when he says it's a good one for night listening sessions with a single malt - very non fatiguing. The two sets of speakers I've listened to it with are around 87db 8 ohm stand mounters. Very happy
 
#844
ajst2duk said:
Well it's been powered up now for about 30 hours - about 6 hours of music. Listening now and there are no warts is far - response across the frequency range seems even - nice detail without being bright. Possibly slightly laid back (warm) presentation but it's very easy to listen to - and it's got good punch for a 50 watter. I think this may become my favorite. I think Hugh is right on the money when he says it's a good one for night listening sessions with a single malt - very non fatiguing. The two sets of speakers I've listened to it with are around 87db 8 ohm stand mounters. Very happy
Click to expand...

Very nice work! Nice layout!

I'm almost done thinking of the casing... 😀

I need to know which design route I will take... I'm finishing my preamp first then will move to it. My two boards are done and signing beautifully. I've put in 50+ hours of music on them.

BTW, where did you get your chassis and heatsinks?

Ciao!
Do
 
#845
Do,

The case is my custom design for the NAKSA 100, what you see, minus the top cover of course, is one single piece of CNC formed 2mm mild steel. The heatsinks are made locally here in Melbourne by a good friend, Julian Wales of Conrad Heatsinks. They are cast, machined, drilled, tapped and powder coated. Andrew bought the case and heatsinks from Aspen.

Syklab,

No problem at all. Just be sure to use 10R for R5.

Cheers,

Hugh
 
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#847
The Plinius has more control of the lower frequencies and greater coherance at louder levels, that's a given at the significantly higher power rating, also the same goes for a Bel Canto REF500S, although that doesn't sound as sweet. Last night I incorporated Fetzilla into our 2.1 A/V system fed by a new NAD M51 digital control centre (dac/pre) and fed by an Oppo 83SE and HTPC/Apple TV both supplying audio via HDMI into the M51. We listened to some music, watch TV then watched a movie - I have to say this system has some great synergy and sounds amazing, the soundtrack was as good as I've heard. Fetzilla seemed to punch above its weight, coping well with the massive transients in the film soundtrack. This system is also the only one I can listen to when everyone is off to bed, so happy to put the Fetzilla there. I will post impressions after a couple of weeks, but so far i'm very happy with this project. - I do have one question, is there any protection for shorted outputs - would this blow one of the PCB fuses? - also I'm using a 2A slo blow for the power fuse as a 1A was blowing on power-up.
 
#848
Andrew,

No protection for shorted outputs aside from the two rail fuses - which should blow after about half a second if BOTH outputs fuse, but may not offer much protection if only one output fuses, since current will be restricted to around 4A through the speaker voice coil.

However, in that instance, you may find that the amp offset controls will work to reduce that short current to a couple of amps, so you would have maybe five minutes of grace before the voice coil was too hot and self-destructed.

Protection is not really indicated on a conservatively designed power amplifier of less than 50W anyway, though DC sense and relay protection, with its sonic hit, is probably a good idea on any amplifier.

Good to hear the FetZilla holds its own with anything out there, particularly knowing it was a whole lot cheaper!

Cheers,

Hugh
 
#850
swordfishy said:
ajst2duk : great to finally hear some listening impressions. How does it compare with vocals? Vocals, IMO, are where fetzilla can hold its own with anything.
Click to expand...
Yes I agree - actually this amp continues to provide pleasant surprises, on vocals it is stunning, but this morning I listened to Roger Waters, The Pros and Cons of hitchiking. This album can create some really vivid soundscapes - and has some pretty challenging (for an amp) transients. I kept waiting for the Fetz to run out of puff but it never did. Now I've punched a couple of serious sized holes underneath it in the rack, it runs at a more moderate temperature as well. I love it, great amp, highly recommend anyone to give it a go. - AJ
 
#852
Hi Woody,

Yes I remember your review. Sorry, I guess what I should have said is "It's great to finally hear some more listening impressions". I've been surprised by the lack of reviews given that there are hundreds of PCBs out there. Though I do understand as I have a bunch of Aleph PCBs sitting unused too!
 
#853
Sword,

I am wondering the same thing, why almost nobody that acquired PCBs is building it. I am using Fetzilla for five months and I am very satisfied with the sound. This is very good amplifier overall, thank again for your input Sword.

George
 
#854
Hi Sword,
I am taking a slow path to build the FETZILLA, selecting, ordering parts and swapping. Also spend time in looking the pre-amp case.

I have to be carefull in handling the resistors since I have problem in differentiate RED/Brown color.

My boards are almost ready, once I drill holes on the heat sink then I can prepare to mount them then fire them up one by one.

IMG_8469.jpg
 
#855
Very nice work, Syklab. You are very methodical!

As a general rule I measure each and every resistor with a DMM to be 100% sure that I put the right resistor in the right place. We humans make lots of mistakes, it is the price we pay for creativity I suspect.

We look forward to your comments about the sound quality!

Cheers,

Hugh
 
#856
Thanks all. My trick is to use industrial 1% resistors with the value written on the side.... Haha , a great way to cheat! I also bend the leads in a way that leaves the value facing up. Makes it easy to see what the design was when I revisit it in 10 years! I use these:

www.vishay.com/docs/31018/cmfind.pdf

Keep plugging away, the amplifier is worth the wait.

Can someone point me in the direction of the current sechematic for the PCB?

P.S. Nice boards syklab.
 
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