Building a DIY amp with NVA amplifier boards

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karatestu
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu » Thu Mar 08, 2018 12:35 pm

Cup of tea was very nice :P No flames when I came back, everything running cool and DC offset where it was before I left the room.

Stunt speakers have been set up and I am currently listening to tunes with my new amps :dance: Monitoring temperature and dc offset - the temp is still cool although I have not given them a work out yet. DC offset has done exactly what the Doc said it would on load :clap:

I am going to keep them playing on the stunt speakers for a while, turning up the volume in stages whilst monitoring heat. Too early to say anything about the music as the stunt speakers are a bit crappy.

Back soon :epopc:
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Dr Bunsen Honeydew
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Re: Building a DIY amp with NVA amplifier boards

Unread post by Dr Bunsen Honeydew » Thu Mar 08, 2018 1:42 pm

You are being tooooo cautious, the amp is fine put it on the big bass bastards / good speakers and play music.

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karatestu
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu » Thu Mar 08, 2018 1:49 pm

Turned up the volume quite a bit and things are playing very nicely. Edit for Doc - they are going on the big speakers as soon as I have had my next cup of tea.

Pic of my trusty variac. Good job I have it as I am all out of broom handles :lol: Sorry for the crap pics I am no photographer and my hands are still shaking from the first turn on.

Image

In the foreground are the thermal pads recommended by Nick. They have sticky backs and so they don't slide about once attached to the heat sink. I like these things, not sure I have got up to 65 deg C yet for them to run and fill the voids. They will for sure when I put them on the isobaric bass cubes :grin:

Pic of them on my coffee table - in the position where I had the filter less Avondale amps.

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I am using LS6 of course and here are the speaker outlet sockets nicely spaced apart. I am still using Naim snaic interconnect between pre and power amps :naughty: and they have spade connectors on the power amp end for direct connection to the NCC200 boards. As I will be swopping back and forth between amplifiers are thought it best to terminate the new amps signal out and 0V connection in spades so I can have quick and easy swop overs. TIS will be bought in due course once all the experiments are over.

An over head pic showing the wiring layout.

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Most of the wiring is done with 2mm tinned solid copper except the AC wiring and the signal in wire which is solid silver. I have a thing about getting space between things (especially transformers and other stuff) and i have extended this to the wiring. I have plenty of space to add another psu per channel for the output stages :grin: The wiring layout will need changing a bit though :roll:

The back panel connections

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I like these speaker outlet sockets, cheap as chips from rapid. Still waiting for the phono sockets i ordered from rapid (they are on back order) and they are fairly cheap too. No point splurging on foo for connectors, going to save my money for lots of TIS :dance: .
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Dr Bunsen Honeydew
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Re: Building a DIY amp with NVA amplifier boards

Unread post by Dr Bunsen Honeydew » Thu Mar 08, 2018 2:04 pm

I thought you built a passive, with Naim pre it will sound shite, and could drive the amp unstable - feckin awful pre-amp.

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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu » Thu Mar 08, 2018 2:19 pm

No I have not built a passive yet - it is on the to do list.

It is not a Naim preamp :naughty: It is an Avondale single ended transconductance jobby with no feedback and only 3x gain. Very few components on it and it blew away the naim pre that it replaced. The Naim snaic is an interconnect (supposedly low capacitance) and is one of the few Naim bits and bobs I still have to use (except the CDP of course). I have one TIS between CDP and pre amp. Need at least three more (phono amp to pre, pre to 4 monoblocs) maybe four if I decide to triamp.

Got the new amps on the small semi Omni cuboids now. Sounds very, very good :dance:

Pic of the business end of the new amps.

Image


Going to put them on the big bastard bass cubes shortly.

Stu
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu » Thu Mar 08, 2018 3:30 pm

Ok, playing a Hammond organ Blue Note compilation with nva amp boards still on mid & tweeter. Big Avondale regulated front end amps on bass for the time being.

Now I remember what my AP20 was like in this system. Heavenly :angelic-blueglow: I was dancing about at home with my four year old daughter a couple of weeks ago when listening to the AP20. The urge to dance and be happy was enormous (even to Jimi Hendrix) and we were both in another world of enjoyment.

Now that I have some nva power amp boards back in my experimental (main) system I transported back to that day at home dancing with my four year old daughter. It is that good. The Avondale's when the filters were removed were much better than stock. I don't know how these nva boards do it but they are even better :guiness; (IMO) I have the biggest grin on my face at the moment. The music is so together, timimg across the frequencies is exemplary. There is a natural airiness to high frequencies. A jazz drummer playing cymbals is really all about relative volume, where to hit the cymbal and if it is the tip or trunk of the stick that strikes. All that subtle information is there with the nva boards. The cymabals shimmer and shine in a way that other amps I have had or heard just can not do. The decay of cymbals are just how they should be and I can tell if the drummer is using wooden tipped sticks or nylon :dance: All of this is not in a forced in your face manner (Naim anyone ?) but a natural way.

Brass instruments have lost the unnatural bite of the avondale set up. They now sound so much better and i have heard tones and micro dynamics from them that simply were not there before. Brass is the hardest section of instruments for me to evaluate because the bands i played in very rarely had any. Even so on the few occasions where one was involved or concerts i have been to, i do love a bit of brass and the way a good musician can play them.

I am now thinking that the band is all playing on the top of their game and in the same room. They have clearly been rehearsing and know the songs well but they are a long way from the point where over fimiliarity and boredom have struck. None of that over played, tired, spiritless performance where the band are just going through the motions and not putting any passion in to it.

I think you may gather that i am over the moon with these new amps. I guess i have gained over the AP20 in the fact that there is one psu per channel, the transformers are bigger, maybe the dc supply voltage is more (don't know) and the transformer is well away from the amp boards.

Things that are different to the AP20 are there is no passive pre, i am using naim transformers and avondale rectifier / cap bank and there is no case around it all. All these things can be changed - different transformers, diy rectifier/ cap bank with hardwired tinned solid copper all the way.

Going to swap the amps around now - nva on bass, avondale mid & tweeter.

:grin: :grin: :grin:
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu » Thu Mar 08, 2018 4:33 pm

The difference between the two amplifiers is as clear as day within the first ten seconds of the first track played with the nva based amps on bass and Avondale on mid & tweeter. These Avondale's are the ones with regulated front end and big transformers but all the filters (input cap, zobel and output inductor) are still intact.

Removing the filters from the Avondale does close the gap to the nva but there is something inherent in the Avondale quasi complimentary design which just can not be gotten rid of. There is a sheen over everything that the nva does not have. The nva is just more musical, full stop. I am not enjoying the music as much with the Avondale on mid & tweeter. The nva based amps on bass are doing a lovely job and the heat sinks are only slightly warmer. I would say the difference between the two amps is a lot less pronounced in the bass but the nva is better to my ears.

Another observation. I have noticed that which ever driver the nva goes on the volume relative to the other driver(s) goes up. This suggests to me that the nva amp boards have slightly higher gain than the Avondale.

Bass is pumping out at the moment - listening to Jamiroquai A funk odyssey. Lots of deep bass on this album. The nva based amps are hardly breaking in to a sweat. The bass is full and wholesome. Every note is clear.

I am going to put the nva back on the mid & tweeter as I am getting more benefit there. I think I might have some Avondale stuff for sale in the not too distant future. My conversion to all things NVA is one step closer to completion. Must get my passive pre stuff ordered and built. And get some more TIS. Oh and upgrade to TSCS. :dance: :dance:

Stu
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Re: Building a DIY amp with NVA amplifier boards

Unread post by _D_S_J_R_ » Thu Mar 08, 2018 4:42 pm

The SNAIC is total crap when used as a 'stereo' interconnect outside of a Naim system in my experience. I found the centre image widened and the far left and right narrowed - very odd, but it ruined the system I was using at the time (it was thirty years ago and I'm not saying what it was)...

If you're using ANY active preamp with the NVA boards, you're seriously on a hiding to nothing, and volume setting may well be too cramped to the bottom of the range compared to a passive with these boards - been there and done it here with three active preamps of different vintages and characteristics, so speak from experience, not because the Doc told me to!!!!!

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karatestu
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu » Thu Mar 08, 2018 5:01 pm

_D_S_J_R_ wrote:
Thu Mar 08, 2018 4:42 pm
The SNAIC is total crap when used as a 'stereo' interconnect outside of a Naim system in my experience. I found the centre image widened and the far left and right narrowed - very odd, but it ruined the system I was using at the time (it was thirty years ago and I'm not saying what it was)...

If you're using ANY active preamp with the NVA boards, you're seriously on a hiding to nothing, and volume setting may well be too cramped to the bottom of the range compared to a passive with these boards - been there and done it here with three active preamps of different vintages and characteristics, so speak from experience, not because the Doc told me to!!!!!
Hi Dave, I hear what you are saying and thanks for all of your advice and the Doc of course :clap: . I can only do one thing at a time :grin:

A passive pre is definitely the next thing on my to do list. A couple of 10K stepped attenuators from hificollective me thinks. The Avondale diy pre is only 3x gain so not too bad. I am not having any problems with the volume control (50K noble pot)at present. That being said it will be saying good bye soon. Once this main system goes home i will need to build something for work so some of the avondale stuff will get used in that. It has done sterling service over the last 10 years though and has let through every upgrade upstream of it.

I am only using one of the signal cores in the snaic and the screeen for 0V return (I know, I know :roll: ). They are all i have to hand at the moment until i get more nva ones - which i definitely will be doing. The TIS i got a while back was a revelation. It will get expensive to do it all in one go unless i go for something a little down the ladder from the TIS. If i triamp then that will be 3 pairs of cables and one pair for the phono to pre.

I am just reveling now in the improvement in musicality these nva boards have brought.
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Dr Bunsen Honeydew
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Re: Building a DIY amp with NVA amplifier boards

Unread post by Dr Bunsen Honeydew » Thu Mar 08, 2018 6:03 pm

AND this is why I (and nva) are blocked off all the other forums and nothing but lies are told about us. I have had to put up with this for over 30 years and people wonder why I am like I am. I have always tried to be truthful but not too promoting but all it has got me is denial. Well I have reached the stage of life where I couldn't give a shit any more. I have never heard an amplifier that competes with nva (apart from on one occasion that still confuses me about 10 years ago) on a musical level. You would think in a hobby like this that would have become apparent, surely people would want to find out. It seems not! being embedded in their own ego and self importance it seems is more important.

Example look at the likes of MartinT, surely if he is such a hi-fi / music enthusiast he would have wanted to find out, but no interest to try just wants to ignore, has more interest in shovelling his money (gross amounts) down the toilet pans that are Coherent and MCRU.

Then you get Marco - lies and libel going back years about bad design bad build etc etc. remember him calling me Fireraiser - disgraceful sub human. So now he pretends we don't exist.

Sorry I am in rant mood, but others in my situation would react the same - it is supposed to be a hobby where excellence and music prevails, yet it is a hobby where in reality bullshit and ego prevails.

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