DIY Transistor Amp Using NVA Boards

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Mike H
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Re: DIY Transistor Amp Using NVA Boards

Post by Mike H » Thu Jan 23, 2020 12:32 am

Top hole. :thumbleft:

Need to get on with mine but keep being distracted.
 
I have boxes and boxes full of components, but never the right ones!

Cressy Snr
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Re: DIY Transistor Amp Using NVA Boards

Post by Cressy Snr » Thu Jan 23, 2020 10:51 am

Mike H wrote:
Thu Jan 23, 2020 12:32 am
Top hole. :thumbleft: ....
ISWYDT :lol:
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steve s
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Re: DIY Transistor Amp Using NVA Boards

Post by steve s » Thu Jan 23, 2020 11:21 am

It would be good to hear it Steve, I too have found what I think is a much better amp than the a20, but im sure people will laugh when I say it's built around the tda2030 chip..
I've owned them for a few years, but eventually give them a try a few months ago.. pretty good in my view.

I've been trying to build an off the net circuit, quite unsuccessfully !.. to see if the sound is recreatable.... I think I'm going to end up copying my originals when I get a chance though.

I've been planning a new valve amp and been back and forth deciding which output valve to use... still not really settled on it.. going back to one power supply.. as a tester, but with an unconventional smoothing arrangement as valve amps go.
I have picked a mains transformer with multiple by taps so switching between choke and cap loading will give a wide HT range, I think I may settle on 250vt globe px4s for testers
Let's see..
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number

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Re: DIY Transistor Amp Using NVA Boards

Post by Cressy Snr » Thu Jan 23, 2020 4:17 pm

steve s wrote:
Thu Jan 23, 2020 11:21 am
It would be good to hear it Steve, I too have found what I think is a much better amp than the a20, but im sure people will laugh when I say it's built around the tda2030 chip..
I've owned them for a few years, but eventually give them a try a few months ago.. pretty good in my view.

I've been trying to build an off the net circuit, quite unsuccessfully !.. to see if the sound is recreatable.... I think I'm going to end up copying my originals when I get a chance though.

I've been planning a new valve amp and been back and forth deciding which output valve to use... still not really settled on it.. going back to one power supply.. as a tester, but with an unconventional smoothing arrangement as valve amps go.
I have picked a mains transformer with multiple by taps so switching between choke and cap loading will give a wide HT range, I think I may settle on 250vt globe px4s for testers
Let's see..
Yes I can imagine that the act of trying to scratch build a transistor device is fraught with difficulties that don’t apply to valve amps. It’s a whole new area to learn about. When I did Engineering Science A level at school, I was more interested in the bit we did on speakers than transistors. Wish I’d paid more attention back in 1975; it would have been far easier to learn about transistors then, than now, when I don’t know what day of the week it is half the time :lol:

I can bring “The Clone” to your place when you’re free if you want to hear it on your speakers.
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izzy wizzy
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Re: DIY Transistor Amp Using NVA Boards

Post by izzy wizzy » Thu Jan 23, 2020 5:47 pm

Nick wrote:
Tue Jan 21, 2020 1:41 pm
For a reference work Self or Cordel would be my suggestion. Probably and instead of or in the last sentence.
Second Cordel. Found it a good read.

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Re: DIY Transistor Amp Using NVA Boards

Post by steve s » Thu Jan 23, 2020 6:37 pm

Cressy Snr wrote:
Thu Jan 23, 2020 4:17 pm


I can bring “The Clone” to your place when you’re free if you want to hear it on your speakers.
That sounds like a plan Steve, can we give it a few weeks.. I'd like to get this valve amp finished and, unfortunately, I'm starting a kitchen refurb at Lesleys daughter's next week, I expect that to take 2-3 weeks, it puts a large spanner in the works regarding my social life..
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number

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Re: DIY Transistor Amp Using NVA Boards

Post by Cressy Snr » Thu Jan 23, 2020 7:36 pm

steve s wrote:
Thu Jan 23, 2020 6:37 pm
Cressy Snr wrote:
Thu Jan 23, 2020 4:17 pm


I can bring “The Clone” to your place when you’re free if you want to hear it on your speakers.
That sounds like a plan Steve, can we give it a few weeks.. I'd like to get this valve amp finished and, unfortunately, I'm starting a kitchen refurb at Lesleys daughter's next week, I expect that to take 2-3 weeks, it puts a large spanner in the works regarding my social life..
Ok no probs.
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Re: DIY Transistor Amp Using NVA Boards

Post by Cressy Snr » Tue Jan 28, 2020 1:12 pm

Thought I’d put the electronic finishing touches to the amp yesterday and fitted 1uF film cap bypasses to all the power supply caps. I sat back, cued up a record and prepared to be enveloped on sonic bliss. Instead I got sandpaper and grit for treble and the whole tone of the thing was completely fooked up. Took them out and returned to liquidity and music.

I’ve never had much sonic success with bypassing PSU electrolytics, the sound is always degraded, despite what other people say. The only real success was with the output caps on the OTL, where the improvements were quite marked.
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Re: DIY Transistor Amp Using NVA Boards

Post by izzy wizzy » Tue Jan 28, 2020 1:43 pm

Cressy Snr wrote:
Tue Jan 28, 2020 1:12 pm
Thought I’d put the electronic finishing touches to the amp yesterday and fitted 1uF film cap bypasses to all the power supply caps. I sat back, cued up a record and prepared to be enveloped on sonic bliss. Instead I got sandpaper and grit for treble and the whole tone of the thing was completely fooked up. Took them out and returned to liquidity and music.

I’ve never had much sonic success with bypassing PSU electrolytics, the sound is always degraded, despite what other people say. The only real success was with the output caps on the OTL, where the improvements were quite marked.
My experience too. It's like adding salt to yer food. A little here and there might be OK for a bit of flavour possibly (on chips only for me) but everywhere is usually too much IMHO. I used to use them everywhere until one day, they all came out, bit by bit, and now never again. I've had success with huge coupling caps but with a series resistor about 1k in the electro leg with the lot bypassed by a film cap. I have soooo many 0.1u and 0.01u caps lying round taking up space.

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Re: DIY Transistor Amp Using NVA Boards

Post by Ant » Tue Jan 28, 2020 2:18 pm

Stop pratting with it and put a front panel on it! :mrgreen:
Hey, wait, I got a new complaint
Forever in debt to your priceless advice

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IslandPink
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Re: DIY Transistor Amp Using NVA Boards

Post by IslandPink » Tue Jan 28, 2020 7:31 pm

Cressy Snr wrote:
Tue Jan 28, 2020 1:12 pm
I’ve never had much sonic success with bypassing PSU electrolytics, the sound is always degraded, despite what other people say.
I find it's always worth reminding yourself of this, from time to time.
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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Re: DIY Transistor Amp Using NVA Boards

Post by Mike H » Sun Feb 02, 2020 8:30 pm

Cressy Snr wrote:
Tue Jan 28, 2020 1:12 pm
I’ve never had much sonic success with bypassing PSU electrolytics, the sound is always degraded, despite what other people say. The only real success was with the output caps on the OTL, where the improvements were quite marked.
This is why I will only use high Voltage polystyrene, if I must bypass elecs caps. I've had the same experience with HV ceramic discs too. My ears (or brain, as the case may be) can't "hear" polystyrene caps, it all sounds clean to me.

If I want larger values, has to be audio grade polypropylene (not power supply filter type ones, motor run etc.)
 
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Re: DIY Transistor Amp Using NVA Boards

Post by Cressy Snr » Tue Feb 04, 2020 5:50 pm

Finished the cosmetics today:
6158A4EB-53ED-4037-A654-2BDD5F1D02F4.jpeg
I was going to order some black perspex, but Melanie wanted a wood finish on the front panel, so who was I to argue?
I must say, she was right; it looks pretty good with a front panel made from an off-cut of engineered pine shelving board I had lying around. The panel was given three coats of clear Briwax and buffed to a deep shine. The different rectangular areas add interest. The body was sprayed matt black from a rattle can and the vent holes are backed with perforated aluminium, also sprayed matt black.
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Re: DIY Transistor Amp Using NVA Boards

Post by Cressy Snr » Tue Feb 04, 2020 6:47 pm

Closer pic of finished amp:
FCE0D353-EA62-4EE4-871D-F4706B324F11.jpeg
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Re: DIY Transistor Amp Using NVA Boards

Post by ed » Tue Feb 04, 2020 10:01 pm

I mean, how shoddy is that!
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