Please do Steve, I (for one) would be interested to hear your NVA clone.Cressy Snr wrote: ↑Fri Apr 15, 2022 11:34 amWell in that case…I’ll think about itIslandPink wrote: ↑Thu Apr 14, 2022 11:11 pm If you need any moral support, i may have one or two monitor speakers with Purifi drivers there - they will have a bit of Boofboof, so you won't feel out of place.
DIY Transistor Amp Using NVA Boards
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#181 Re: DIY Transistor Amp Using NVA Boards
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
- Cressy Snr
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#182 Re: DIY Transistor Amp Using NVA Boards
Well three days into life with the Missions and the treble has come out beautifully. The speakers were a little rolled off last Thursday, but now they are nicely balanced, with no sibilance or harshness anywhere in the upper-mid/treble area.
I found this phenomenon interesting so removing the tweeter, so I could see the crossover, I found a simple first order job, with an inductor on the bass driver and a cap plus padding resistor on the tweeter. There’s also baffle step compensation in there.
The tweeter cap is a 4.7uF Tesla electrolytic, so that probably explains why the treble extension improved over time. The cap, not having been used in years will have taken time to re-form. There may be a bit more treble improvement to come, but they are sounding pretty damn’ good whatever.
There could be an argument for replacing the tweeter cap with a higher quality film/foil item, but why mess about? That way lies madness. Too many different makes of cap.
The NVA/Mission combination sounds excellent. The amp, now it is playing into more suitable speakers, is doing nothing wrong at all and seems to be providing fatigue free musical enjoyment, completely different to the Naim amp I had, twenty years ago.
As Phil has inferred, I might as well bring the Missions and the NVA clone to Owston in October. Obviously the system won’t cause any jaws to drop, but there’ll be no problem carrying the Missions to the car, which is a big bonus at my age.
Re the amp itself, I’ll use it with the cover off, so the panel can take a look and make suggestions as to how the twin power supplies might be improved on. If they don’t mind that is.
Haven’t stopped grinning for two days.
I found this phenomenon interesting so removing the tweeter, so I could see the crossover, I found a simple first order job, with an inductor on the bass driver and a cap plus padding resistor on the tweeter. There’s also baffle step compensation in there.
The tweeter cap is a 4.7uF Tesla electrolytic, so that probably explains why the treble extension improved over time. The cap, not having been used in years will have taken time to re-form. There may be a bit more treble improvement to come, but they are sounding pretty damn’ good whatever.
There could be an argument for replacing the tweeter cap with a higher quality film/foil item, but why mess about? That way lies madness. Too many different makes of cap.
The NVA/Mission combination sounds excellent. The amp, now it is playing into more suitable speakers, is doing nothing wrong at all and seems to be providing fatigue free musical enjoyment, completely different to the Naim amp I had, twenty years ago.
As Phil has inferred, I might as well bring the Missions and the NVA clone to Owston in October. Obviously the system won’t cause any jaws to drop, but there’ll be no problem carrying the Missions to the car, which is a big bonus at my age.
Re the amp itself, I’ll use it with the cover off, so the panel can take a look and make suggestions as to how the twin power supplies might be improved on. If they don’t mind that is.
Haven’t stopped grinning for two days.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
#183 Re: DIY Transistor Amp Using NVA Boards
Steve, I have a pair of Mission 773 floorstanders you're welcome to take off my hands, FOC, if you want to explore a little more? They're like these;
They're in good running order and cosmetically pretty reasonable with no dings to the cabinets. The leather effect covering on the baffle has shrunk a little on one, so shows a sliver of the baffle material, and there are a couple of small scuffs. The gril cloth has some small scuffs but would be easy to replace I think. I can take some pictures if of interest?
They're in good running order and cosmetically pretty reasonable with no dings to the cabinets. The leather effect covering on the baffle has shrunk a little on one, so shows a sliver of the baffle material, and there are a couple of small scuffs. The gril cloth has some small scuffs but would be easy to replace I think. I can take some pictures if of interest?
Sorry, I couldn't resist!
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#184 Re: DIY Transistor Amp Using NVA Boards
Fantastic Ray!Ray P wrote: ↑Sun Apr 17, 2022 9:16 am Steve, I have a pair of Mission 773 floorstanders you're welcome to take off my hands, FOC, if you want to explore a little more? They're like these;
They're in good running order and cosmetically pretty reasonable with no dings to the cabinets. The leather effect covering on the baffle has shrunk a little on one, so shows a sliver of the baffle material, and there are a couple of small scuffs. The gril cloth has some small scuffs but would be easy to replace I think. I can take some pictures if of interest?
I’ll have them. If you bring them to Owston, I’ll certainly take them off your hands.
Yep, take a few pics.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
#185 Re: DIY Transistor Amp Using NVA Boards
Here you go Steve. They're n the spare room so a bit dusty but you'll get the general picture. I also have the stablising feet somewhere here when I find them.
Here's a couple of general pictures;
This shows where the leather stuff on the baffle has shrunk;
And these are close-ups of the little scuffs they've got - shouldn't be a problem to a man of your talents.
Here's a couple of general pictures;
This shows where the leather stuff on the baffle has shrunk;
And these are close-ups of the little scuffs they've got - shouldn't be a problem to a man of your talents.
Sorry, I couldn't resist!
#186 Re: DIY Transistor Amp Using NVA Boards
Size wise, they're about 86cm tall, 17cm wide and 27cm deep.
Sorry, I couldn't resist!
#187 Re: DIY Transistor Amp Using NVA Boards
If anyone from up your way is passing through Somerset on the M5, on the way to/from Devon or Cornwall, I'm happy to meet them at Taunton Deane Services so you get them sooner.
Sorry, I couldn't resist!
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#188 Re: DIY Transistor Amp Using NVA Boards
Do you fill the bottom halves of the cabs with ballast, or am I thinking of a different model?
Sgt. Baker started talkin’ with a Bullhorn in his hand.
#189 Re: DIY Transistor Amp Using NVA Boards
There's no ballast in them Steve. I don't think they're intended to have it either as i can't see an obvious way of getting it in. TBH, I've not really done anything with them beyond checking them - I picked them up from a guy at work who was moving abroad and was just going to take them to the tip.
Sorry, I couldn't resist!
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#190 Re: DIY Transistor Amp Using NVA Boards
Must be thinking of a different speaker then.
As I said, I can definitively use them, no problem. I’m all for recycling.
As I said, I can definitively use them, no problem. I’m all for recycling.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
#191 Re: DIY Transistor Amp Using NVA Boards
Steve, I'm listening to the Mission 773s with my SissySIT amp that I've just been working on.
Not ideal because using my mobile phoe as a source there's not enough gain so I've pressed my Noir HPA into service as a preamp, still not quite enough to drive them ard but certainly listenable volume.
It shows that they've not been used for years and it's a new amplifier too, sound is a little dull and the bass is a bit light but some hours and a bit more power into them should loosen things up a bit - already sounding better after just half an hour.
Not ideal because using my mobile phoe as a source there's not enough gain so I've pressed my Noir HPA into service as a preamp, still not quite enough to drive them ard but certainly listenable volume.
It shows that they've not been used for years and it's a new amplifier too, sound is a little dull and the bass is a bit light but some hours and a bit more power into them should loosen things up a bit - already sounding better after just half an hour.
Sorry, I couldn't resist!
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#192 Re: DIY Transistor Amp Using NVA Boards
The Mission 731s did the same, so there should be a bit more improvement to come.Ray P wrote: ↑Tue Apr 19, 2022 3:57 pm Steve, I'm listening to the Mission 773s with my SissySIT amp that I've just been working on…
…It shows that they've not been used for years and it's a new amplifier too, sound is a little dull and the bass is a bit light but some hours and a bit more power into them should loosen things up a bit - already sounding better after just half an hour.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
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#193 Re: DIY Transistor Amp Using NVA Boards
Took a break from decorating and got the stands for the Missions done. I just have to decide on the finish for the bases.
Right now I have a yard to clear, a load of tools to put away and I’m knackered. But I’ve achieved something, so I’m happy.
Just need the poles to be black and white and I have a set of traffic lights.
Right now I have a yard to clear, a load of tools to put away and I’m knackered. But I’ve achieved something, so I’m happy.
Just need the poles to be black and white and I have a set of traffic lights.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
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#194 Re: DIY Transistor Amp Using NVA Boards
It didn’t take long for me to conclude that the tops of the stands look like crap.
The solution was a couple of large toroidal transformer washers: The stands now look a whole lot better: The construction is dead simple. The bases are a four layer glue-lam made of 12mm ply. The stands are held together by an M8 threaded tie rod passing up the pipe and it holds everything in compression. Years ago I had a pair of B&W stands under my KEF Coda IIIs that used the same principle.
As you can imagine, these much taller versions are far from rigid. Their main resonant frequency is around 3Hz - way below the audio band. However despite the lack of rigidity, the sound is superb. It was very good with the wooden top platforms, but with the washer platforms, the sound is outstanding for a pair of budget speakers.
Also because I designed the Fane full range speakers for my own room, they could just be thrown in and would sound good. With the Missions, I have had to re learn how to position speakers in a room. They ended up 10.25in out from the back wall, toed in a couple of degrees and spaced 66in apart.
I couldn’t be happier with the result.
The solution was a couple of large toroidal transformer washers: The stands now look a whole lot better: The construction is dead simple. The bases are a four layer glue-lam made of 12mm ply. The stands are held together by an M8 threaded tie rod passing up the pipe and it holds everything in compression. Years ago I had a pair of B&W stands under my KEF Coda IIIs that used the same principle.
As you can imagine, these much taller versions are far from rigid. Their main resonant frequency is around 3Hz - way below the audio band. However despite the lack of rigidity, the sound is superb. It was very good with the wooden top platforms, but with the washer platforms, the sound is outstanding for a pair of budget speakers.
Also because I designed the Fane full range speakers for my own room, they could just be thrown in and would sound good. With the Missions, I have had to re learn how to position speakers in a room. They ended up 10.25in out from the back wall, toed in a couple of degrees and spaced 66in apart.
I couldn’t be happier with the result.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
- Cressy Snr
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#195 Re: DIY Transistor Amp Using NVA Boards
Like all speakers, the Missions are front heavy. They are wider than they are front to back, so even more front heavy than a more modern speaker. Due to the stand’s top platform now being circular, there isn’t a lot of resistance to the tendency for the front to try to tilt downwards, ie only a single point at the underside of the front.
I had visions of the blu tack gradually giving way at the back and the speaker crashing forwards off the stand in the middle of the night and killing the cat.
Anyway, I’ve solved that with a couple of 3mm aluminium strips epoxied to the big washer: that should stop any toppling shenanigans.
I had visions of the blu tack gradually giving way at the back and the speaker crashing forwards off the stand in the middle of the night and killing the cat.
Anyway, I’ve solved that with a couple of 3mm aluminium strips epoxied to the big washer: that should stop any toppling shenanigans.
Sgt. Baker started talkin’ with a Bullhorn in his hand.