JBL 308P and 708P

[jajo]

I am not sure if my understanding is right but that ST STA350BW is directly functioning as a power amp so there is for the 308 only signal conversion analog into digital and the 350 is some kind of a digital power amp?

„Two channels can be provided by two full-bridges, providing up to 2 x 50 W of music power, by using standard 6 Ω speaker or 2 x 40 W by using 8 Ω speakers at 25 V“
In this case one loudspeaker has one chip so the two channels could go to the LF and the HF loudspeaker driver.
That fits with the mentioned 56W per driver power.

Yes, JBL is using Class D amplification in 308/708. That is really the only tech that works in such a small space and used in basically all monitors.

[Defender]

what I was trying to say is the 708 transfers analog to digital and than digital to analog and than drives the ClassD amp

where the

308 transfers analog to digital and than uses a digital amp directly without transferring back to analog before
so it seems one conversation less.

I know its a theoretical discussion.

[FairPlayMotty]

what I was trying to say is the 708 transfers analog to digital and than digital to analog and than drives the ClassD amp

where the

308 transfers analog to digital and than uses a digital amp directly without transferring back to analog before
so it seems one conversation less.

I know its a theoretical discussion.

The codec chip is a combined DAC and DSP unit.

[Lego]

I am not sure if my understanding is right but that ST STA350BW is directly functioning as a power amp so there is for the 308 only signal conversion analog into digital and the 350 is some kind of a digital power amp?

„Two channels can be provided by two full-bridges, providing up to 2 x 50 W of music power, by using standard 6 Ω speaker or 2 x 40 W by using 8 Ω speakers at 25 V“
In this case one loudspeaker has one chip so the two channels could go to the LF and the HF loudspeaker driver.
That fits with the mentioned 56W per driver power.

Yes, JBL is using Class D amplification in 308/708. That is really the only tech that works in such a small space and used in basically all monitors.

So when you say Class D ,you mean D asin Digital Jajo?

[FairPlayMotty]

I am not sure if my understanding is right but that ST STA350BW is directly functioning as a power amp so there is for the 308 only signal conversion analog into digital and the 350 is some kind of a digital power amp?

For the 3 series the Cirrus ADC does analogue to digital conversion, the STA350BW converts the digital to analogue, controls the DSP and resultant amplifier control. The specs don't worry me a jot - my ears like the result. A guy on another forum said words to the effect that the 708P was the best speaker he'd heard but he was selling them because he didn't like the ADC or DAC chip specification - there lies confusion (at best).

[lejonklou]

So when you say Class D ,you mean D asin Digital Jajo?

The D in Class D doesn't stand for digital. It's an amplifier working with pulses instead of linear waveforms.

[jajo]

I am not sure if my understanding is right but that ST STA350BW is directly functioning as a power amp so there is for the 308 only signal conversion analog into digital and the 350 is some kind of a digital power amp?

For the 3 series the Cirrus ADC does analogue to digital conversion, the STA350BW converts the digital to analogue, controls the DSP and resultant amplifier control. The specs don't worry me a jot - my ears like the result. A guy on another forum said words to the effect that the 708P was the best speaker he'd heard but he was selling them because he didn't like the ADC or DAC chip specification - there lies confusion (at best).

Very stupid to judge by specs instead of listening.

708P is without doubt the best speaker I've heard and I couldn't care less about the technical solutions used when it is obviously very well implemented for musical performance.

[jajo]

I am not sure if my understanding is right but that ST STA350BW is directly functioning as a power amp so there is for the 308 only signal conversion analog into digital and the 350 is some kind of a digital power amp?

„Two channels can be provided by two full-bridges, providing up to 2 x 50 W of music power, by using standard 6 Ω speaker or 2 x 40 W by using 8 Ω speakers at 25 V“
In this case one loudspeaker has one chip so the two channels could go to the LF and the HF loudspeaker driver.
That fits with the mentioned 56W per driver power.

Yes, JBL is using Class D amplification in 308/708. That is really the only tech that works in such a small space and used in basically all monitors.

So when you say Class D ,you mean D asin Digital Jajo?

No, see Fredriks response. But the Class D-amps are highly suitable for integration in digital signal chains (when a DSP is in use).

[FairPlayMotty]

Very stupid to judge by specs instead of listening.

708P is without doubt the best speaker I've heard and I couldn't care less about the technical solutions used when it is obviously very well implemented for musical performance.

Couldn't agree more. If you don't trust your ears it's maybe time to change hobbies (or lifetime passion) to collecting stamps :)

Sprinkle liked the chips so much in his time at JBL it's almost exactly the same with the big selling Kali LP6. If it ain't broke.......

[Lego]

So when you say Class D ,you mean D asin Digital Jajo?

The D in Class D doesn't stand for digital. It's an amplifier working with pulses instead of linear waveforms.

Thanks Fredrik

[Defender]

when you say the KAN stands having a 60cm height is that already with spikes and on Linn Skeets?
What hight have the stands which Fredrik uses (KATAN stands?) again with or without spikes/Linn Skeets

[lejonklou]

I have Kan stands and Katan stands. Although I am quite certain that the Kan stands are of a superior design, the slightly higher Katan stands are better in our apartment. Perhaps due to its high ceilings?

I can measure the exact heights when I get back home if you want. But if curious about the optimal height of a particular loudspeaker, I recommend finding it out by experimenting, using for instance a stool and a pile of books. It's enough to listen to one speaker only, just keep the distance from the rear wall the same and reasonably optimal. It doesn't matter if the loudspeaker is unstable, it's still very obvious when you reach the optimal height.

[Defender]

I have two stands which I will try. Both are not Linn ones. One is a Mission Stand which will be about 60cm high with spikes and the other is a B&W Stand which will be at around 63cm with spikes so I am in about the right range.
But yes if you dont mind and if its not to much hassle it would be great to know the hight of the Katan and Kan stands.

[lejonklou]

Will do, in a couple of days!

[V.A.MKD]

I have Kan stands and Katan stands. Although I am quite certain that the Kan stands are of a superior design, the slightly higher Katan stands are better in our apartment. Perhaps due to its high ceilings?

I can measure the exact heights when I get back home if you want. But if curious about the optimal height of a particular loudspeaker, I recommend finding it out by experimenting, using for instance a stool and a pile of books. It's enough to listen to one speaker only, just keep the distance from the rear wall the same and reasonably optimal. It doesn't matter if the loudspeaker is unstable, it's still very obvious when you reach the optimal height.

Thank you Fredrik for sharing your experience ...

[Klanters]

Hi Forum,

Am I right in saying that there's only one version of the 708p (unlike the 308p where I understand that mk1 is great and mk2 not so great).

To put it simply, would one have to worry about getting the correct version of the 708p?

Thanks!

[Lego]

Hi Forum,

Am I right in saying that there's only one version of the 708p (unlike the 308p where I understand that mk1 is great and mk2 not so great).

To put it simply, would one have to worry about getting the correct version of the 708p?

Thanks!

There's only one model of 708P Klanters .

[Defender]

are there any rough torques available for the bass unit of the JBL308? what would be the range to work in?

I wondered why I heard some sounds which dont sound right and it seems the front of the JBL308 can be brought into resonance/rattling with some frequencies and I hope I can tame them with torquing the bass unit.

[matthias]

Recently I did refasten the bass and CD horn of my JBL3677s without a torque meter and I am happy with the final result.

[snatex]

Have you heard the 705P Jajo?

I read Floyd Toole's account of a demonstration of the M2, 708P and 705P. Supposedly the audience thought they were listening to the M2. They asked when they could hear the smaller boxes. They were already listening to the 705P :)

Using M2 with Tundra Mono and an analogue filter would be very interesting. I don't doubt that it would be a real knock out.

What kind of analogue filter would you need to play the 708i or M2 with Tundra Mono's? Would it be difficult and complicated?

[jajo]

Have you heard the 705P Jajo?

I read Floyd Toole's account of a demonstration of the M2, 708P and 705P. Supposedly the audience thought they were listening to the M2. They asked when they could hear the smaller boxes. They were already listening to the 705P :)

Using M2 with Tundra Mono and an analogue filter would be very interesting. I don't doubt that it would be a real knock out.

What kind of analogue filter would you need to play the 708i or M2 with Tundra Mono's? Would it be difficult and complicated?

Needs to be tested.

JBL recommends using their DSP amplifiers with a digital filter that they built. The curves can be found on the internet, but they can only be used with a configurable filter (most likely there are no analogue filters that can do the trick).

My experience with digital crossovers and EQ are not the best. I have owned the Crown XTI2002 and it performed a lot worse with the processing enabled.

A pure standalone crossover solution could be something from MiniDSP, but my experience with their performance is not great.

My gut feeling is that the only thing that would be really good is an analogue filter built specifically for the speaker. This is of course a lot of work and no one knows how good the end result will be. But then again, the 308P/708P perform great despite using digital crossovers, so there might be products out there that would work great. But finding them is not going to be the easiest task.

/ Jacob

[lindsayt]

Needs to be tested.

JBL recommends using their DSP amplifiers with a digital filter that they built. The curves can be found on the internet, but they can only be used with a configurable filter (most likely there are no analogue filters that can do the trick).

My experience with digital crossovers and EQ are not the best. I have owned the Crown XTI2002 and it performed a lot worse with the processing enabled.

A pure standalone crossover solution could be something from MiniDSP, but my experience with their performance is not great.

/ Jacob

That's the thing with DSP. It can make things worse. Which when you think about it, makes sense.

What sounds more tuneful than a circuit in the signal path? No circuit at all. Where you can get away with getting rid of the circuit.

The use of DSP is a pragmatic one. I've heard a room, system, listening position combination that was so bad that the bass sounded really untuneful, to the point that it made music difficult to listen to, Because the bass was so overwhelming and so bloomy sounding. With DSP the bass was to some extent reigned-in, resulting in an overall better listening experience.

DSP - from my experience of it so far - appears to be fine for mitigating major faults elsewhere in the system.
But it's better if you don't have those major faults in the first place.

Trying to fix a fault in a system with an inverse fault elsewhere is not the optimum path to a great sound.

[jajo]

Needs to be tested.

JBL recommends using their DSP amplifiers with a digital filter that they built. The curves can be found on the internet, but they can only be used with a configurable filter (most likely there are no analogue filters that can do the trick).

My experience with digital crossovers and EQ are not the best. I have owned the Crown XTI2002 and it performed a lot worse with the processing enabled.

A pure standalone crossover solution could be something from MiniDSP, but my experience with their performance is not great.

/ Jacob

That's the thing with DSP. It can make things worse. Which when you think about it, makes sense.

What sounds more tuneful than a circuit in the signal path? No circuit at all. Where you can get away with getting rid of the circuit.

The use of DSP is a pragmatic one. I've heard a room, system, listening position combination that was so bad that the bass sounded really untuneful, to the point that it made music difficult to listen to, Because the bass was so overwhelming and so bloomy sounding. With DSP the bass was to some extent reigned-in, resulting in an overall better listening experience.

DSP - from my experience of it so far - appears to be fine for mitigating major faults elsewhere in the system.
But it's better if you don't have those major faults in the first place.

Trying to fix a fault in a system with an inverse fault elsewhere is not the optimum path to a great sound.

Well, it is not exactly the same.

When JBL created these speakers, they left some "trimmings" to the digital domain that they also control (through their recommended amplifiers and their settings).

I don't have the knowledge to say if this is good or bad, but I know that the amps in my 708P are performing great and that my experiments with the Crown amps left much to be desired. At this point in time I would strongly recommend going for the powered versions rather than the passive, but if Lejonklou would make an analogue filter optimised for a JBL speaker, I would surely reconsider...

[Fred11]

Just finnished my 308 project. I have boxes them into plywood. They Play really well, even though I have a bad source right now (Apple tv-naim dac awaiting Källa). I have not compared systematically without boxes. I also have a Kikkin. They now feel like big Spendor speakers. I have also made the sideboard, but I am contemplating making a smaller sideboard and get some good stands for them. So it seems this is also a possibility with these cheap and excellent speakers.
F

[Fred11]

Without grills.