Super Pensil 12

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@Michael

@Michael

Member
Joined 2022
#1
Hi all,
I have built a pair of a Super Pensils 12, on Alpair 12p. But I`am not happy with the sound. They sounds very bright, pain sparky high range, with poor mids and average low end. That is after about 200h of playing. So I have a question to the pensils owners/users: are you got the same experience? What is best aplifier to pair with Alpair 12p? Do you have in you`re pensils any kind of baffle correction?
Thx
 
#4
Room is 20m2 with speakers on short wall, 4m long.
Denon DCD 1550AR Is my cd player that I use most often. Sound giving by Denon is detailed and airy, high frequency orientated. Spotify is the second source, Arylic A50 network player.
I tested two amps, Musical Fidelity E10 and NAD 302, MF E10 is too bright, NAD sounds much better, tho is a budget amp, with it`s limitations. My plan is to buy decent amplifier, that will fit well Pensils. But so far I have no idea which way I shoud go. I wish to tame high`s of the Alpair and add some scene/ space on midds.
 
#6
Given the size of the Pensil12, 18mm MDF would need significant bracing. 15mm quality plywood would out perform.

@Michael said:
fully braced as on KJF plans
Click to expand...

Link? Not esily findable.

Here is an example of simple braces for a SuperPensil. Likely insuffucent for MDF.

SuperPensil12-holey-braces.jpg


But i doubt thany issues would not casue your issue.

I would check out what Jeff said. Typically people seem to settle on about ⅔ the specified damping. And, all too often, we see the damping insufficiently teased. Bernie just built a set of smaller A11ms Pensils and complained that tesing the acoustastuff took 3 hours.

dave
 
#8
I don't know what 'worm and juicy' sounds like but I can make a guess. The BG20 isn't really a horn driver -especially if the horn is a relatively compact type, and in the handful of applications I've seen where it's used that way, it's likely to have significant gain peaking in the midbass. Its response also falls off rapidly above ~9KHz.

The pensils are not designed to be lagged but stuffed, with the density adjustable by the user (that was a specific feature of the design & why they have a removable rear baffle, to facilitate tuning in that way). 'Poor mids and average low end' doesn't really tell us a lot though since we don't know what you mean by either. Lack? Excess? Ringing? Something else?
 
#10
Scottmoose said:
The pensils are not designed to be lagged but stuffed, with the density adjustable by the user (that was a specific feature of the design & why they have a removable rear baffle, to facilitate tuning in that way).
Click to expand...
Curious, Vb = ~2.377x A12's Vas, which of course nothing wrong for the alignment type, but combined with a < 0.3 Qts, seems like the OP's "poor mids and average low end" (high roll off corner to a tuning plateau my assumption) is to be expected if not driven with some form of high output impedance, so was it designed for other than the A12?
 
#11
No, both were designed for the 12P, assuming an amplifier output impedance + wire R falling roughly into the 0.5ohm - 2.5ohm range as the 12P was done leaning in the over-damped direction & MA wanted something to suit SET etc. users without going OTT in that direction. FWIW, as designed, quasi-anechoic responses attached. Slightly different conditions; IIRC (it's a few years ago now so don't quote me 😉 ) Pensil12P nearfield was spliced in at 450Hz; from fallible memory the larger SuperPensil12P nearfield was blended in over a wider window as it was done at a different time / location. My own preference was always the smaller for its higher gain -it's basically the intended alignment with the latter being an optional extra for those who wanted an extra 10Hz or so extension. Loses out a bit in the upper bass / lowest end of the midrange (but will likely to an extent depend on room behaviour).
 

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#15
vinylkid58 said:
It would appear that KJF missed the memo on that, as their kit is supplied with both the lagging AND ployester stuffing, even though there is no mention of lagging in your design desription.
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Stefan likes to provide a few extras; no harm in it, providing the 'user adjustable' mantra is kept in mind, which in fairness isn't always easy to do with kits, since many kit buyers tend to want something relatively plug & play.
 
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#16
I second the suggestion to check stuffing. My regular (not super) 12p Pensils sound great and learned something years earlier when I had the same problem with the A7m Pensils....to much un-teased stuffing. I removed almost half of it and when I really teased up the remaining stuffing, it came up close to the bottom of the driver and sounded so much better than before...

Mario
 
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#20
Not Pensils per se, but the same genre was originally whatever tube amp was in various tube consoles and later a Mac MC275. 45 - 78, and early 33 rpm, cassette sounded best with tube (no surprises there!) and the Mac for RTR tapes, later 'anything'.
 
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