kono supiikaa ha tiisai desu ga, oto ga ii desu.

この must be followed by a noun, so この スピーカー means this speaker.

By contrast:

• これ = this one / this
• この = this + noun

So:

• これは 小さいです。 = This is small.
• この スピーカーは 小さいです。 = This speaker is small.

スピーカー is a loanword from English speaker, so it is normally written in katakana, which is often used for foreign-derived words.

Its pronunciation is closer to supiikaa than to the English pronunciation of speaker.

In Japanese, スピーカー usually refers to an audio speaker, not a person giving a speech.

The particle は marks the topic of the sentence.

So この スピーカーは means something like:

• As for this speaker, ...
• This speaker, ...

The rest of the sentence gives information about that topic:

• 小さいですが、音がいいです。
• It is small, but the sound is good.

So the sentence structure is basically:

• Topic: this speaker
• Comment about it: it is small, but its sound is good

小さい is an い-adjective. With い-adjectives, you keep the い and add です for politeness.

So:

• 小さい = small
• 小さいです = is small

You do not remove the い before です.

This is different from な-adjectives, which do not end in い in the same way. For example:

• 静かです = is quiet

But for い-adjectives like 小さい, 高い, 新しい, the い stays.

That が means but.

So:

• 小さいです = it is small
• 小さいですが = it is small, but...

This が is a conjunction connecting two ideas.

A very important point: this is not the same role as the が in 音がいいです.

In this sentence there are two different がs:

• 小さいですが → but
• 音がいいです → subject marker

They are written the same way, but their functions are different.

Here, が is the subject marker.

• 音 = sound
• 音がいい = the sound is good

So in this part, 音 is the thing being described as good.

This is a very common pattern in Japanese:

• 頭がいい = smart / has a good head
• 背が高い = tall / has a high stature
• 字がきれい = has neat handwriting
• 音がいい = has good sound

Even though English might say It sounds good, Japanese often says it more literally as Its sound is good.

音がいい is the most natural neutral way to say the sound is good or it has good sound quality.

Using は instead would change the nuance. 音はいい often suggests contrast, such as:

• The sound is good, but something else is not
• At least the sound is good

So:

• 音がいい = straightforward description
• 音はいい = contrastive emphasis

In your sentence, the contrast is already expressed by ですが: It is small, but the sound is good. So 音がいい fits naturally.

Yes, but in this sentence it specifically refers to sound quality.

So 音がいい often means:

• The sound is good
• It has good sound quality
• It sounds good

This is a very common natural expression for audio devices like speakers, headphones, and microphones.

いい and よい both mean good.

In modern everyday Japanese, いい is much more common in ordinary speech. よい can sound a little more formal, stiff, or written depending on context.

So:

• 音がいいです = very natural everyday Japanese
• 音がよいです = also correct, but less casual/everyday

A useful thing to know: although the dictionary form is often taught as いい, some conjugations come from よい, such as:

• よくない = not good
• よかった = was good

That surprises many learners.

Japanese often states more directly which aspect of something is good, bad, high, low, etc.

So rather than saying only It is good, Japanese frequently says things like:

• 音がいい = the sound is good
• 形がきれい = the shape is beautiful
• 色がいい = the color is good
• 使いやすい = it is easy to use

In this sentence, smallness and sound quality are being contrasted, so Japanese names both qualities explicitly:

• It is small
• Its sound is good

Not always. が after です can mean but, but the strength of the contrast depends on context.

Here it clearly means:

• It is small, but the sound is good.

In other situations, が can be softer, almost like:

• and
• though
• although
• or even just a sentence-linking device

For beginners, but is a good translation here, but it is helpful to know that Japanese が can be gentler than English but.

Yes. Without です, it becomes less polite and more casual:

• このスピーカーは小さいが、音がいい。

or more naturally in everyday casual speech:

• このスピーカーは小さいけど、音がいい。

The version with です is polite and appropriate in many normal conversations.

So roughly:

• 小さいです が、音がいいです。 = polite
• 小さいけど、音がいい。 = casual

Normally, standard Japanese is written without spaces.

So the usual writing would be:

• このスピーカーは小さいですが、音がいいです。

Spaces are often added in beginner materials to make the sentence easier to read. They are a learning aid, not standard spelling.

Yes. けど also means but and is very common in spoken Japanese.

So you could say:

• このスピーカーは小さいけど、音がいいです。

That sounds natural, especially in conversation.

Very roughly:

• が = a bit more formal or neutral
• けど = very common and conversational

Both are correct here.