Double Chamber Reflex Mark Audio Alpair 10p or 12.2p ????
- Thread starter bianchi
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As Dave says, not a lack of interest as such. It's just that ye interlocutor here has not been in mid-season form for a little while, & is currently writing some lectures while also engaged in a lengthy (& hopeless) job search.
A few quick notes, FWIW:
A few quick notes, FWIW:
- The 12P is a lower Q unit which was designed partly with an eye to those running higher output impedance amplifiers, or are willing to make an equivalent adjustment if you want to take it to relatively low frequencies. With the right amplifier or equivalent measures, you can actually take it quite low. I might do a few boxes like that (I've already done some) when time allows, since I'm rather fond of the 12P, and it tends to fall under the radar a bit, which is a shame since it's actually rather flexible.
- If running a pure voltage source (more or less) then sans any kind of additional measures, you either need a horn variation or decent sized QW box for best LF results
- A large box in & of itself will not necessarily give more usable (note caveat) LF extension. Depends on the box, the system & the design objectives. Several of my recent boxes for e.g. were done as traditional alignments, and either assume a higher amplifier output impedance, or equivalent measures taken for optimum results
- On a slightly different subject, while wide baffle speakers are less common than narrow baffle designs, they are not exactly a Grimm exclusive. Dave and I have done many wide baffle designs over the last two decades (my favourite being a 32in wide x 72in tall MLQW for the old Pioneer B20), and that's just us. To say there are plenty of other DIY and commercial examples would be a chronic understatement.
There just aren't as many as narrow-baffle designs, because that is what the majority of people seem to want these days for various reasons. - Pushing the baffle step frequency down to < 300Hz, where room-gain should start to naturally compensate in many situations, is no bad thing, since you're potentially gaining acoustic efficiency. Potentially. Depends on the natural response of the driver in the first place, that of the room, and whether any passive low-pass shelving filters are in place or not.
- Stating that pushing baffle-step to somewhere between 100Hz - 400Hz inherently makes for a cleaner midband is more questionable. My first reaction to that would be 'if that is an issue, then you either need to set your speakers up better, or treat the room'. But that is over-simplified, and the counter-argument that 'not everybody can do that' is fair enough in itself. However, since not everybody can use wide baffle speakers either, that too is an over-simplification. What is unquestionably true though is that a wide-baffle speaker is certainly not guaranteed to solve any such problem. It might. It might not. Assumptions count for nothing.
I need someone to help me determine if my tube integrated amp has a high or low output impedance. According to Scott's designs and posts, this seems to be an important amp spec which may help in deciding what speaker to choose.
I have a Finale F128 SEP EL84 6 watts integrated amp with a 8 ohms speaker RCA output. I was told in the past that the output impedance is about 1 ohm.
How can I know for sure? Is 1 ohm considered high or low?
Thanks
I have a Finale F128 SEP EL84 6 watts integrated amp with a 8 ohms speaker RCA output. I was told in the past that the output impedance is about 1 ohm.
How can I know for sure? Is 1 ohm considered high or low?
Thanks
I'm glad Scottmoose managed to bring attention to the importance of the drive impedance. 1ohm is typical for your tubes and topology I`d say. There's not much info on the company's website, e-mail might work. It`s not that high and yet should not be overlooked. It`s probably safe to add 0.5 ohm for cabling and connections. With 1.5 ohm, your 19L looks good with tuning between 40-50Hz, adjust for room and preference. You haven`t yet stated what it is though, so I'll also come around for a second and third charge, respectively:
I`m just trying to give your present 12.2P enclosure a fighting chance for you to like it. Maybe it still won`t cut it after making sure all is being done, but I think it`ll then be more reasonable to consider a new build.
- What is the tuning frequency for the 19 liter reflex enclosures?
- Is baffle-step being dealt with? Either physically or electronically or both.
I`m just trying to give your present 12.2P enclosure a fighting chance for you to like it. Maybe it still won`t cut it after making sure all is being done, but I think it`ll then be more reasonable to consider a new build.
I do seem to recall at least one of their models had a built-in low-frequency shelf that could mitigate baffle-step, but the published response of the 12P leads me to believe it has not been so blessed.
At Fb~50Hz, the alignment should be decent with a bit of drive impedance as mentioned above. Position relative to walls or corners can help. Passive or active BSC should bring bass up in-line with the midrange. The full 6dB is likely not required, 3-4dB is usually more like it.
https://diyaudioprojects.com/Technical/Baffle-Step-Correction-Circuit-Calculator/
https://sound-au.com/bafflestep.htm
At Fb~50Hz, the alignment should be decent with a bit of drive impedance as mentioned above. Position relative to walls or corners can help. Passive or active BSC should bring bass up in-line with the midrange. The full 6dB is likely not required, 3-4dB is usually more like it.
https://diyaudioprojects.com/Technical/Baffle-Step-Correction-Circuit-Calculator/
https://sound-au.com/bafflestep.htm
Nice amplifier.
Andy also has this amplifier, i talked with the designer, IIRC the Rout is abour 1Ω. 1Ω is approximately the
border”
Not all the data may need some adjustment but it gives an idea.
dave
Generally speaking the 12P, like most of the other units, doesn't need any EQ under the majority of practical conditions, although it depends on the exact speaker type / alignment, driving amplifier & positioning. I'm fairly familiar with the driver for obvious reasons -and the minor fact that I actually had some input into that unit's design. So while I wouldn't rule it out if used in an acoustically large space away from boundaries, especially if in conjunction with a low output impedance amplifier and / or something like an EBS alignment, in most other situations, it's quite well-balanced as-is. Since I design multiways as well as single driver types, I have no particular bias one way or another -I just call it as I see it.
They sound great, but I also have 20W/ch to play with. I have a suspicion that the congestion you mentioned earlier with your 10p's is just a function of low amplifier power. I've head a few single ended amps being pushed hard, and that's exactly how they sound at the onset of clipping. Just a thought.
jeff
Thanks Dave,
That picture is actually my amp. Frank took pictures for his website before sending it to me.
So, does that make it a high or low output impedance amp? Do I need to worry about the resistors that Scott recommends for some of his plans?
Would I have to add these resistors to the DCR Juliet 12.2p if I decide to go ahead with it?
Should I wait for the BVR designs?
That picture is actually my amp. Frank took pictures for his website before sending it to me.
So, does that make it a high or low output impedance amp? Do I need to worry about the resistors that Scott recommends for some of his plans?
Would I have to add these resistors to the DCR Juliet 12.2p if I decide to go ahead with it?
Should I wait for the BVR designs?
Clipping is a bad thing. How bad depends on how wel behaved your amplifier is as it approaches clipping and how well it recovers if it does clip.
SE amps typically compress before they clip, soft clipping in other words, but it does describe what you are hearing.
Where the volume control is has little bearing as what power the amplifier is outputting depends on how hot the signal going in is.
dave
SE amps typically compress before they clip, soft clipping in other words, but it does describe what you are hearing.
Where the volume control is has little bearing as what power the amplifier is outputting depends on how hot the signal going in is.
dave
A12pw miniOnken bass performance was questioned. They get to 35 Hz or so, the same drivers in Scott’s ML-TL is 10 Hz lower.
Quattrofish has also built both, he has some opinions (he also went from 1 to 2 A12pw per side). Makes a big difference.\
One “strange” thing is that a pair of A12pw in miniOnkens takes up more space than the ML-TL.
dave
Quattrofish has also built both, he has some opinions (he also went from 1 to 2 A12pw per side). Makes a big difference.\
One “strange” thing is that a pair of A12pw in miniOnkens takes up more space than the ML-TL.
dave
bianchi,
Given the questions coming up on amplifier clipping, you can consider trying (testing) the Pensil 10P with a different amp?
There's an entry level Class D amp called the Aiyima A07 that you can check out. It is in no way the "best" amp out there, but will give you a frame of reference to compare the speakers vs when driven with tube gear. It was around US $80 on Amazon last time I checked.
Even if you prefer tube amplifiers in your system, this can serve as more of an observation and learning experience - testing out different things makes this hobby fun (at least for me).
Given the questions coming up on amplifier clipping, you can consider trying (testing) the Pensil 10P with a different amp?
There's an entry level Class D amp called the Aiyima A07 that you can check out. It is in no way the "best" amp out there, but will give you a frame of reference to compare the speakers vs when driven with tube gear. It was around US $80 on Amazon last time I checked.
Even if you prefer tube amplifiers in your system, this can serve as more of an observation and learning experience - testing out different things makes this hobby fun (at least for me).
Yes, I do have a Marantz 1070 integrated amp that I can test them with but this clipping thing got me worried a bite. How can I get confirmation that it is clipping and not something else that I am hearing. Like I said in a previous post, I'm not good at describing sound. The congestion that I am hearing when listening to rock can also be from the recording.
BTW, is clipping dependent on speaker design?