+3 sound quality?

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animaal
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+3 sound quality?

Post by animaal » Sat Jan 11, 2020 2:30 pm

Hi. I had a +2 (grey) back in the day. It was my only computer for many years, until I eventually downgraded to a Pentium PC :)

More recently, I managed to get myself a +3. I used to lust after a Spectrum with a disk drive and now I have one.

I refurbished it - changed the capacitors, Scart fix, audio fix. Regarding the audio, it was just awful! now that it's fixed, it's great, similar to the sound quality of my old +2.

Was this a big deal in the 80s? I don't remember reading about +3 sound quality in magazines, but I might not have taken too much notice if it was discussed.

If I had turned on a new +3 and heard the sound quality, I would probably have returned it, thinking it was faulty. I suppose in a way they all were.
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Ast A. Moore
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Re: +3 sound quality?

Post by Ast A. Moore » Sat Jan 11, 2020 2:52 pm

I guess the +3 was not produced in substantial quantities, unlike the +2A, in which the issue was later corrected (and the new model received the +2B moniker). There was technically a +3B, but it was extremely rare and, as far as I can tell, was only released for the Spanish market.

That said, the original 128K and +2 also had a sound issue—the beeper and AY-chip audio were extremely unbalanced. Those were never officially fixed, in spite of several logic board revisions.

I never owned any of the Amstrad machines back in the day, so I can’t say for sure. When I purchased a Toastrack a couple of years ago, I fixed the audio myself, and my Amstrad machine is a +2B.
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patters
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Re: +3 sound quality?

Post by patters » Sat Jan 11, 2020 3:34 pm

I certainly never knew of anyone with a +3, which supports that hypothesis.
Incidentally, the toastrack which I recently bought has had the Beeper-AY resistor fix, but the beeper is still a fair bit louder. However, overall a lot quieter than my 48K when connected to my TV. After your own fix, are they more or less equivalent volume, or does the beeper still out do the AY? I saw there are several ways to do the mod, so I'm wondering if it's worth me re-doing.
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Re: +3 sound quality?

Post by AndyC » Sat Jan 11, 2020 5:31 pm

Isn't the beeper thing intentional? The manual describes the beeper volume as being as loud as all three AY channels at full volume.
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Re: +3 sound quality?

Post by animaal » Sat Jan 11, 2020 5:59 pm

Yes, I remember reading that about the +2, which is why I never really thought it was a bug.
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Re: +3 sound quality?

Post by 1024MAK » Sat Jan 11, 2020 6:56 pm

animaal wrote:
Sat Jan 11, 2020 2:30 pm
If I had turned on a new +3 and heard the sound quality, I would probably have returned it, thinking it was faulty.
Apparently some people did...

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Ast A. Moore
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Re: +3 sound quality?

Post by Ast A. Moore » Sat Jan 11, 2020 7:02 pm

patters wrote:
Sat Jan 11, 2020 3:34 pm
After your own fix, are they more or less equivalent volume, or does the beeper still out do the AY? I saw there are several ways to do the mod, so I'm wondering if it's worth me re-doing.
I went for them being more or less equal in volume. It really all depends on the value of the resistor you use. Here’s my mod:
Image

(Note: This will only affect the volume on the MIC output; not through the RF modulator.)
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Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.

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Ast A. Moore
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Re: +3 sound quality?

Post by Ast A. Moore » Sat Jan 11, 2020 7:05 pm

AndyC wrote:
Sat Jan 11, 2020 5:31 pm
Isn't the beeper thing intentional? The manual describes the beeper volume as being as loud as all three AY channels at full volume.
Hmm. Can’t find it anywhere in the manual. Could you tell me the page number? (I just went through this searching for words like “loud” and “volume” to no avail.)
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Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.

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Re: +3 sound quality?

Post by animaal » Sat Jan 11, 2020 7:14 pm

If you look at the +2 manual, page 121:

"As previously mentioned, BEEP is louder than a single channel of PLAY, but if all three channels play a note at volume 15, then it should be at the same level as a note produced by BEEP"
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Ast A. Moore
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Re: +3 sound quality?

Post by Ast A. Moore » Sat Jan 11, 2020 7:32 pm

animaal wrote:
Sat Jan 11, 2020 7:14 pm
If you look at the +2 manual, page 121:

"As previously mentioned, BEEP is louder than a single channel of PLAY, but if all three channels play a note at volume 15, then it should be at the same level as a note produced by BEEP"
Thanks! That explains that, then.

By the way, the volume difference on the MIC jack of the Toastrack (or the SOUND jack of the +2) is much more drastic than on the RF. That might explain why most people didn’t notice it.
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Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.

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