| François |
I call the project: Clabby (Clone Abby)
What do you think about these simulations?
http://www.diyaudio.com/forums/show...9765#post509765
I want a good compromise between cloning the look and cloning the sound. I am also planning to use solid wood to do the TL. |
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| TC |
The real Abby is not very expensive .
TC |
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| gl |
Mr. Cain,
My complements to you on your loudspeakers. As you say they are not expensive. In fact considering the artistry, the time, and the quality materials put into them they represent a true bargain. I too am a life long woodworker and I appreciate what you have achieved.
That being said, this is after all, a DIY forum. You need to expect that the people here will generally choose to build rather than buy if possible. But I suspect that your comment was tongue in cheek.
Since you are here as a member I would like to ask you a couple of questions about your Abbey loudspeaker. You have included a turned. round plate behind the driver as a design element. Seigfried Linkwitz has some very interesting half space frequency response curves that he recorded using circular and square open baffle backing plates. These are on his web site and show significant comb filtering effects for the circular plates. I was wondering why you chose to use the circular plate as opposed to none at all. The port you use seems a bit small for the Fostex driver used and I was also wondering what the design rational was for the oval shape as opposed to square. Comments?
Regards,
GL |
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| Nelson Pass |
Terry has made his choices, some of which contradict
conventional wisdom. From the little I know about how
he proceeds, his product contains a great deal of trial
and error and his decisions are based on listening more
than anything else. The result is an excellent product
which I'm happy to say I bought and use. :cool: |
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| reverber |
FrankDIY,
A strange connection just closed in my mind...
You aren't by any chance moonlighting as a wine steward for a guy named Marcel, are you?
http://www.marcelgagne.com/
Cody |
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| FrankDIY |
| quote: | Originally posted by TC
The real Abby is not very expensive .
TC |
I agree Mr Cain. The price asked for these speakers is very low. Unfortunatelly they are not available in Montreal and like most people here, we enjoy DIY and we love designing new projects or cloning great ideas. I did the same thing with many projects from Pass Labs. See that project a rewards for your unique and great quality product. Nobody on this forum is cloning bad product. I think this is a good sign :)
Seeing the pass few comments, I am very proud to see I have generated interest from two famous people ;)
This pair of speaker will be presented in a contest that I am organizing in Montreal. Any comments on my design will be always appreciated.
| quote: | Originally posted by reverber
FrankDIY,
A strange connection just closed in my mind...
You aren't by any chance moonlighting as a wine steward for a guy named Marcel, are you?
http://www.marcelgagne.com/
Cody |
No connection with that guy :)
Thanks for your comments! |
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| TC |
Thanks for the compliments gl. Yeah, I was attempting a veiled "funny".
The circular baffle projects the speaker out and away from the main baffle. With all the edges rounded with a long gradually decreasing radii, diffraction effects have been minimised. While I am sure some artifacts could be measured bouncing off the baffle I doubt it adds anything annoying that you could hear. It has been speculated that the baffle I make contributes to the large soundstage my spkr seems able to produce, again by elevating the driver off of the main cabinet a bit. Moreover I was interested in further reducing cabinet energy from reaching the driver by adding the (circular) mass. "Comb filtering" effects would be something that 2 drivers do, or two radiation points.. The diffraction effects of a single driver _can_ be seens as comb filtering though i see it as a stretch, implying first order cancellations. Not having read SL's paper you mention I am only guessing. The added mass and fluid surface adds benefits to the rest of the spectrum, if a slight cancellation/reinforcement results from a circular baffle it must be very slight.
Now if the circular baffle had sharp edges and was flush with the driver for it's circumference that could be easier to measure a step.
The port area was arrived at by building many a pipe. The design subscribes to alot of different theories about Voigts. I rely primariliy on actual physical modeling and measurements to arrive at these designs after the initial design work is complete. Choking off the pipe reduces ripple and pipe effect. The oval shape creates a wider sloping, fluid velocity value, lowering it's own self noise. May not even be audible vs a circular port.
TC |
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| FrankDIY |
| This is very interesting. Based on these affirmations, I guess you did not use any baffle step compensation and then keep the efficency very high. |
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| TC |
| quote: | | . Based on these affirmations, I guess you did not use any baffle step compensation and then keep the efficency very high. |
Right.
| quote: | | we enjoy DIY and we love designing new projects or cloning great ideas |
Thanks again. and good on ya.
TC
Here's a link to a nice clone http://cls.audiogon.com/cgi-bin/cls...full&1105182133 |
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| gl |
Mr. Cain,
Thank you for your gracious and detailed reply. I appreciate you sharing your design experiences with us. I also appreciate you taking the time to answer my questions. I am experimenting with FR stuff at the moment and those particular questions about the Abbey have been in the back of my mind for a while.
Regards,
Graeme |
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| FrankDIY |
| Using an open baffle testbox, I did some measurements on the speakers. There is no break-in yet, I was just too curious. |
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| Nelson Pass |
That's a little better than I get at 1 M with the speakers away
from walls. Where did you measure? - nevermind, I see from
the picture. :cool: |
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| chris ma |
Why this kind of close measurement? What does it serve? I do not listen at such close range. I think measurement taken from listening position make or useful information. IMHO
The Butcher |
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| FrankDIY |
| quote: | Originally posted by Nelson Pass
That's a little better than I get at 1 M with the speakers away
from walls. Where did you measure? - nevermind, I see from
the picture. :cool: |
In my own anechoic room :D (basement)
This is nice to see that my modest measurement equipment can produce good results.
| quote: | Originally posted by chris ma
Why this kind of close measurement? What does it serve? I do not listen at such close range. I think measurement taken from listening position make or useful information. IMHO
The Butcher |
This is just priliminary measurements to see the FR of the speaker. Nearfield measurement is useful to minimize room effect on the measurement when you don't have an adequate room. I was also doing this to see the influence of the break-in period on these Fostex.
When the enclosuse will be finished, I will be able to make measurement at the listening position. |
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| FrankDIY |
Here is some news about this project.
This week I have built two prototypes. The first one (big one) is my own design based on the MathCad sheets.
The second one is very close to the real Abby. Unfortunatelly I do not have access to a real pair of loudspeaker so the dimensions are based on published data and picture approximation. I have no clue about the damping so I used this ratio: 2/3 of the box at 0.5 lbs/ft3.
The sound is surprisingly similar for both boxes. One problem I noticed is that the sweet spot of my design is pretty high due to the angle of the baffle.
The picture of both boxes:
The measurements (green=the small box, pink=the big box):
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| chrisb |
Having some experience listening to real Abby's, as well as a few DIY fullrangers, (horns/ TQWP) I would suggest that MDF is not the most suitable material for the enclosure, and most definitely for the round baffle.
If I'm not mistaken, Terry uses raw "standard" particle board for the back panel and perhaps ( with veneer) for the sides as well. The front flat panel and round baffle are edge laminated solid hardwood. I'm not sure whether he uses different species, or just a talented finisher.
If I ever get a chance to visit his factory, I'll know for sure, but only after signing that non-disclosure agreement.
And don't overlook the 200 or so hours of mandatory break-in on the Fostex drivers. After about 4 months, my FE108E Sigmas are finally opening up and developing some reasonable bottom end extension and weight in the Buschhorn enclosure.
Anyways, if you're encouraged by you initial results, you owe the design the opportunity to shine with at least Baltic Birch plywood. As for the round baffle, you could always get creative with a spoke-shave. |
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| jleaman |
| Have you heard or seen dave? * chris *.. you going to sound hounds tonight ? |
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| chrisb |
As of noon, we've got about 6" of fresh snow here in Langford at the bottom of "the mountain" . I'd suspect that not even Dave is crazy enough to venture out with the threat of 4 or 5 more by day's end.
I'm barely gonna make it home with my light duty "all season" tires.
OTOH, maybe that's why we can't reach him! That's not a snow bank, that's Dave!
For myself, no - the last few times the expresso machine was broke down, and I'm still recovering from my last overdose of the professor, and I still have to finish that EL84 amp for Dave. (no smoke to let out, but still some "Lou")
Cheers |
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| jleaman |
| LOL hope to get the lou out. I start work soon Monday to BE exact. Dave is not on line or no phone. Weird we only have a few " here in town. wonder how thick it will get : O ) |
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| FrankDIY |
| quote: | Originally posted by chrisb
If I'm not mistaken, Terry uses raw "standard" particle board for the back panel and perhaps ( with veneer) for the sides as well. The front flat panel and round baffle are edge laminated solid hardwood. I'm not sure whether he uses different species, or just a talented finisher.
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As far as I know, he uses only solid wood all around. That will not make a big difference for now. Solid wood is easier to resonate so could color the music. |
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| GrahamnDodder |
Mr. Cain-
I have long wished I could hear a pair of Abbys. Is there anyone who carries them in Baltimore or Washington?
I did not see any dealers listed on the website. I'd be happy to even know of anyone here who bought them in the BaltoWash area and would let me hear them in exchange for their 6-pack of choice...
:D
GnD |
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| coredump |
Chris,
I'd rather not spoil this thread, but you refuse PMs on this forum. I'd like to ask you a couple of questions about the stuffing you used in your Buschhorns (if you used any).
Any possibility of a private conversation?
Best regards,
Oliver |
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| chrisb |
Coredump:
Damping the CC on the MKII design was a little bit of trial and error, and in my case was done totally by ear. Futhermore the break-in period of Fostex is legendary, so it's a long time 'til you're sure you're listening to the right thing.
Anyway, I'll have to pull the driver to quantify it. |
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| coredump |
Chris,
| quote: | chrisb wrote:
[...]Futhermore the break-in period of Fostex is legendary, so it's a long time 'til you're sure you're listening to the right thing. |
so I noticed. ;-)
I made a "felt belt" around the driver (just glued some felt to the inside of the cabinet), as the drivers suffered from some bad reflections. As a result, I had to remove some wool as it started to sound over-damped. Tricky business.
| quote: | | Anyway, I'll have to pull the driver to quantify it. |
Don't bother, I'll keep fiddling. Thanks anyway. :-)
Best regards,
Oliver |
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| chrisb |
| quote: | Originally posted by coredump
Chris,
so I noticed. ;-)
I made a "felt belt" around the driver (just glued some felt to the inside of the cabinet), as the drivers suffered from some bad reflections. As a result, I had to remove some wool as it started to sound over-damped. Tricky business.
Don't bother, I'll keep fiddling. Thanks anyway. :-)
Best regards,
Oliver |
My felt was recycled from old speaker boxes (courtesy of Dave/Planet10) and was approx 1/2" thick. I recall lining the side walls of the CC, and either 2 or 3 rather irregularly stuffed layers along the back wall.
FWIW, I'd consider the configuration of the CC on this particular enclosure in need of serious design. No doubt other DIY'ers have concluded the same, and perhaps could post their findings ( on another thread) |
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| Nelson Pass |
| quote: | Originally posted by GrahamnDodder
I have long wished I could hear a pair of Abbys. Is there anyone who carries them in Baltimore or Washington? |
I listen to Abbys nearly every day for light entertainment.
They wear well on the ears over the long haul. :cool: |
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| Christof |
I also built a pair of clones a while back and will give a little info as I know it. I am almost certain that Terry uses Alder for his cabinets or the baffles anyway. Alder is a very very soft (hard)wood and could probably be replaced with American Cherry if you have trouble sourcing it. I was told the upper portion of the cabinet, above the driver, is filled. The lower portion is unfilled. I lined mine with asphalt. I did not use a circular baffle as Terry did but did make a rectangular baffle with rounded edges.
And now the props to Terry. I am absolutely in love with these little TQWT's. They are used in my all tube system and excel at music based on female vocals, jazz, stringed instruments.... If I was not a DIY guy or professional woodworker I would have purchased these from Terry and they would be worth every cent spent.
c. |
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| johnb |
Christof wich speaker are you referring to?
John |
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| Christof |
Abby w/ FE167E
c. |
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| EUVL |
Just wonder if any one (Mr. Cain?) has tried a tapered pipe with circular cross section, in which case the area would change quadratically (rather than linearly) with pipe length.
Any advantages / disadvantages ?
Thanks in advance,
Patrick |
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| planet10 |
| quote: | Originally posted by EUVL
Just wonder if any one (Mr. Cain?) has tried a tapered pipe with circular cross section, in which case the area would change quadratically (rather than linearly) with pipe length.
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Why would the taper not be linear?
Andy got the Conehead using translam before he set the project aside (forever he says but you never know)
dave |
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| planet10 |
Rick Shultz built a TL with a non-linear taper with good results...
http://www.t-linespeakers.org/proje...near/curve.html
Another fellow developed a TL with a reverse exponential taper -- he was going to try to get a patent, but finally just put it into the DIY community.
dave |
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| cheesehead |
| quote: | Originally posted by planet10
Why would the taper not be linear?
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The taper (increase in diameter with length) would be linear, but the cross-sectional area A=(pi)*r^2 would be quadratic with length. (Seems weird to me too, but the math don't lie.)
Should be able to sim it in MJK's sections worksheet, approximating a quadratic profile by using many different linear sections?
cheesehead |
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| GM |
Greets!
AFAIK the worksheets (WS) are only using the cross sectional areas (CSA) at each end and the length to define a conical expansion of whatever its 'M' factor (taper ratio) turns out to be, so doesn't matter what CSA shape you input, ergo if you build a very high aspect ratio cab WRT width/depth, the sim won't be as accurate above the cab's compression BW.
Of course if you want to define a specific 'M' factor with 'x' BW, such as exponential (M = 1), then SL and length become the variables and the 'sections' WS will need to be used.
GM |
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| azira |
| quote: | Originally posted by cheesehead
The taper (increase in diameter with length) would be linear, but the cross-sectional area A=(pi)*r^2 would be quadratic with length. (Seems weird to me too, but the math don't lie.)
Should be able to sim it in MJK's sections worksheet, approximating a quadratic profile by using many different linear sections?
cheesehead |
I think you're mistaken about a rectangular cross-section being different than a circular cross-section.
circular:
A = pi*r^2 -- quadratic.
rectangular:
A = x * y -- linear?
Since the ratio of x:y stays constant because of the linear taper,
x = k*y where k = x/y
so:
A = (k*y)*y = k*y^2 -- quadratic as well.
Since MJKs worksheets just consider CSA w/rt to taper, it doesn't know whether you're using a circular or rectangular shape. However, the taper ratio is different.
--
Danny |
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| cheesehead |
I think we're saying the same thing, just not reading the same thing... ;)
In most cases, when you're changing the cross-sectional area of a speaker, only one dimension is changing. Say, rectangular baffle and triagonal side. Let h be the distance from the top of the "pipe", with a cross-sectional area (CSA) of zero at the top, then
x = constant (the baffle is the same width throughout)
y = c * h (the width of the side is linear with the distance from the top)
CSA = x * y = c * x * h linear with distance from the top
For a cylindrical pipe where the radius is linear with the distance from the top,
r = c * h
Then,
CSA = pi * (c * h)^2 = pi * c^2 *h^2 quadratic with distance from the top
You could get the same thing by building a square pyramid...
In any case, I think you could use MJK's sections program, and enter a number of sections with linear increase in CSA but increasing "taper" to approximate a quadratic increase in CSA. |
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| purplepeople |
| quote: | | The transmission line geometry must be a smooth linear transition, along the length, from the closed end area S0 to the open end area SL as shown in Figure 1. |
This is from page 18 of MJK's TL Alignment Tables.
I read this to mean that a cross-sectional area at any point X along the line length is predictable by equation. Any deviation from the original rate of change would make this impossible. Never mind that in practice, a stepped transition doesn't make much difference.)
:)ensen. |
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| FrankDIY |
Hello,
I finally finished my Clabby. See the attached picture. They sound great! I may have a chance to compare them with the real Abby at the Hi-Fi Montreal Festival in april. Usually there is a room with the Abby and I always spend a lot of time in it.
I decided to ignore a bit all the calculation I did with MJK sheets and also take into accound the dimensions of the real Abby. It is a compromise between both design.
Just for fun, I tried to use a BSC and it completely destroyed the mid-range. Basically I was using a very similar version of the BSC used by MJK for his FE164 project.
I am now using them with a pair of ASL wave-8. Honessly I prefer this match over my Pass Zen V4. I will probably build the first version of the Zen (apprently better for full-range speaker?) or maybe the Zen Lite is better?
Anyway, I will have to do some experiementation.
Nothing special in these speakers: FE167E, silver-plated copper wire with teflon insulation, high quality binding post (but not the cardas), 5/8'' MDF, African Mahogany veneer finished with danish oil.
BTW, please start a different subject if this is not to discuss about the Abby, thx. |
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| Nanook |
They look good Francois.
I too am looking at building something like this. My nephew has the TL/Voight bug. His Dad gave him 2 pairs of DCM TF 250's and he loves em and wanted to "hotrod" them. I suggested that a completely new speaker might be just as easy (He still wants to mod them in addition to building some others).
I have always like TLs and have heard a few. When I stumbled across the Voight pipes on the Internet I was intriqued.
Email me if you would allow a couple in depth questions.
nanook |
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| FrankDIY |
| Thanks :) If you have any specific question, dont hesitate to ask me by e-mail. |
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| EUVL |
François
Does the Mathcad Sheet on your webpage still correspond to the latest dimensions ?
Thanks,
Patrick |
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| FrankDIY |
| No, my web site is not up to date. Using the dimensions of the real abby as well as the paramters of the drivers gives funny frequency response in the calculation sheet. I tried to make a compromise between the ideal box and the shape of the real Abby. BUT, my current listening test show me that there is not a big different in musicality between the "ideal" box and the real Abby box. I will stick to that design and publish the results on the web. Yesterday I did some measurement using my microphone and found that it was really good. A bit of exageration (few db) in the mid-range but no major problem. |
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| EUVL |
Am planning to build the same and therefore really interested in your current design (dimensions) and results.
If you are not prepared to post, may I contact you in private for some tipps ?
Thanks,
Patrick |
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| james_b |
| Do you have any photos showing how much you stuffed the cabinets, or can you describe what you finally wound up using? Did you even play around much with varying the amount? Thanks |
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| FrankDIY |
| I am using around 0.5 lbs of stuffing material per cubic feet. 2/3 of the box is filled. I did not experiment a lot up to now. |
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| mtiberi |
Hello FranckDIY,
I'm interested too with your drawings of Clabby cabinets. Is it possible to have them ?
Regards
Michel:) |
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| FrankDIY |
| I am currently working on them, they will be published soon on my web site. I am impressed by the interests I got from people around the world, I got a lot of e-mails !! |
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| FrankDIY |
I have put more details on my web page, enjoy :)
Here are the measurements...
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| Nelson Pass |
Interesting that you have a pronounced dip at 60 Hz. Any
thoughts on where that came from? |
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| planet10 |
| quote: | Originally posted by Nelson Pass
Interesting that you have a pronounced dip at 60 Hz. Any
thoughts on where that came from? |
most likely a room mode
dave |
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| qwad |
:D good one[ or right on] no 99
cheers and have a happy and safe easter T.C.:D if you drink, dont drive, or dont drive if you drink:angel: |
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| MJK |
| The peaks and dips look like combined floor bounce and baffle step. If you look at my Figures 9.31 and 9.32 in my Advanced Back Loaded Horn Design article you will see a similar curve for a ML TL style of enclosure. |
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| FrankDIY |
| quote: | Originally posted by Nelson Pass
Interesting that you have a pronounced dip at 60 Hz. Any
thoughts on where that came from? |
This is a good question. Like the previous people are mentionning, this could be a room mode because the measurements have been made at the listening position. Unfortunatelly I can not do the measurement outside of the house because this is winter here :)
It could also be related to what MJK is mentionning. I could add some absorbing material on the floor and compare. I tried the exact same BSC of MJK project (FE164E) and the results were really bad, it completely destroyed the mid-range so now there is no crossover, this is more zen ;)
My measurement setup is a behringer ECM8000 + Apex mic preamp + trueRTA and I was using an ASL wave 8 as the amp. The results are pretty much the same with my Zen V4.
Let me know if you have any suggestion |
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| MJK |
Measurements are only one part of the picture.
How do they sound? If you are happy with the performance then who cares how they measure.
If you are not happy with the performance then do they sound like they measure? Probably weak bass and dominant midrange and high end. If this is the case then you need to take some corrective actions.
My guess is that you will never solve the deep nulls. But a reworked BSC filter might help with the rebalancing of the SPL resposne. I am not sure what filter you tried and discarded. |
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| FrankDIY |
I tried your BSC Martin (http://www.quarter-wave.com/Project02/Parts_List.pdf)!!
They sound great actually. Yes the mid is more present but the tonal balance is not so bad and I enjoy very much listening to them. I found they are sounding better on tube amp then my Zen but I guess I will have to build a more appropriate Zen :) |
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| qwad |
| ;) MJK is correct , l was just too tazy to type it all out, his summation is absolutely on the ball:xeye: cheers T.C. |
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| MJK |
Now I am really confused. First Frank DIY wrote :
| quote: | | I tried the exact same BSC of MJK project (FE164E) and the results were really bad, it completely destroyed the mid-range so now there is no crossover, this is more zen |
| quote: | | Yes the mid is more present but the tonal balance is not so bad and I enjoy very much listening to them. |
Not so bad? That is a long way from "Great!".
Did you try making adjustments to the circuit? That particular circuit was the one that worked well in my room, with my amp, and my personal taste in bass/midrange response. A 1 ohm change in the parallel resistor makes a significant change in the SPL response. With a tube amp (low damping factor) the resistor value should be much less then what I used for my 200 watt SS amp (high damping factor) in Project #2.
You can also increase or decrease the inductor value to shift the transition frequency up (smaller value) or down (larger value).
You have to tweak the circuit to mesh with your particular situation. I bet if you revisited the circuit and tried a few lower values of resistance and maybe a smaller inductor you might find that the sound inproves over what you have without a BSC circuit.
The only way this might not work out is if you have a low power tube amp which just runs out of steam. Have you tried a higher power SS amp and with the original circuit?
Again, you have to tweak the BSC circuit component values to get the optimum response for your situation. The choice is yours, if you are happy and satisfied with the current performance that is all that matters. Personally, I see room for improvement after seeing that SPL plot. I lived with a similar plot for a while. |
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| TC |
| quote: | | Not so bad? That is a long way from "Great!". |
What you gain in flat response, you will loose in "dynamics, tone and transparency" adding such circuitry. Unless you sneak around the absorption and impedance effects these have on signals, amps etc. and use current source amp. "D_T_and T". Everything is a tradeoff. He's already traded some acoustic chips for good tone by using a low watt tube amp. I bet it sounds great.
The dip could well be positioning. (ok it is also his pointy top) .
Bringing the speakers closer together always results in better midbass in any room. Imagery densifies and I bet measurements would prove it
TC |
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| FrankDIY |
Let me recap...
They sound great. I mostly listen to jazz music and to me, I don't want to add a crossover. The only thing I might tweak in the future is the damping. I want also to keep the efficiency as high as possible.
Based on your comments, I will try to do other measurements soon (different positionning and I will try to reduce the room effect). |
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| MJK |
François
If you are happy that is all that matters.
But looking at that measured response I believe a filter would really help. The filter has to be tweaked to mesh with your other equipment and room.
I lived with the same type pf response from my FE-164 ML TQWT for many months and the pronounced midrange and high end definitely made the speaker sound dynamic and super detailed at the expense of the bass output. But I grew tired of this light low end response after a while and feel that the circuit really helped. There was no body or weight to the music without the filter, it sounded good but was just not realistic and lacked depth. This type of response is very appealing and does sound more open, but it is basically still out of balance. With the BSC filter nothing is lost or compromised, it is just returned to the right proportion in the sound level picture.
Putting a correction filter in series with a voltage driven speaker is the same as putting a filter in parallel with a current driven speaker. The filter adjusts the signal transmitted to the driver be it voltage or current. So any degradation added by a filter is present in both circuit/amp topologies. |
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| Nelson Pass |
| quote: | Originally posted by MJK
Putting a correction filter in series with a voltage driven speaker is the same as putting a filter in parallel with a current driven speaker. The filter adjusts the signal transmitted to the driver be it voltage or current. So any degradation added by a filter is present in both circuit/amp topologies. |
I always thought so until I tried it both ways - using a parallel
resistance with a current source and a series resistance with
a voltage source, which should be equivalent. Strangely
enough, they did not sound the same. Jon Ver Halen of Lowther
America reports similar results. I suppose we could chalk it up
to the intrinsic difference in the sound of the two amps, but that
is not what Jon thinks. Me, I see it as topic for additional
experimentation. |
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| MJK |
Nelson,
Where was the sound different? Was the bass and mid-bass different, was it diferent across the entire frrequency spectrum, or were the highs different in some way? How significant were these differences? I have not had the benefit of hearing a current source amp with my Lowthers.
I hate to draw conclusions until I have an apples to apples comparison. I see too many hard conclusions drawn and stated in audio based on a test of one variable in a system when the variable significantly impacts other things in the system response. For example, people conclude that a BSC is a bad thing based on putting it into a system with a 2 watt amp and having the amp run out of gas. The circuit is doing its job, the amp is the limitation. But the conclusion is that the circuit killed the dynamics of the performance.
The point I was trying to make was that series components are in the signal path for a voltage source amp and will have no effect on a current source amp. For a current source amp, parallel components are in the signal path while series components are not. I have seen people conclude that with the current source amp and parallel circuits that there is nothing in the signal path. This is based on the topology of the connections and not on the simple AC circuit theory. They have never heard of Thevenin and Norton. |
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| Nelson Pass |
| quote: | Originally posted by MJK
Nelson,
Where was the sound different? Was the bass and mid-bass different, was it diferent across the entire frrequency spectrum, or were the highs different in some way? How significant were these differences? I have not had the benefit of hearing a current source amp with my Lowthers.
I hate to draw conclusions until I have an apples to apples comparison. I see too many hard conclusions drawn and stated in audio based on a test of one variable in a system when the variable significantly impacts other things in the system response. For example, people conclude that a BSC is a bad thing based on putting it into a system with a 2 watt amp and having the amp run out of gas. The circuit is doing its job, the amp is the limitation. But the conclusion is that the circuit killed the dynamics of the performance.
The point I was trying to make was that series components are in the signal path for a voltage source amp and will have no effect on a current source amp. For a current source amp, parallel components are in the signal path while series components are not. I have seen people conclude that with the current source amp and parallel circuits that there is nothing in the signal path. This is based on the topology of the connections and not on the simple AC circuit theory. They have never heard of Thevenin and Norton. |
I agree with your points, certainly to the extent that the voltage
source and current source are purely that, which of course they
aren't. I've not had difficulties with BSC (baffle step correction so
well described on your site) , and I find them easy to do on with
a current source. I have been getting good results using values
between 10 and 47 ohms across the amp terminals (the amp
itself being 80 ohms).
When I go to simulate this with a resistance in series with a
voltage source (for me usually an Aleph 30) by placing the
resistance, something seems to take away the toe-tapping
qualities of the experience, as I said, contrary to my
expectations. I've done with with Abbys and Lowthers-in-a-box
and heard similar things. I recall Jon Ver Halen describing it
as having the "life sucked out of it", but in any case it was
different.
At this time, I regard it as an anecdotal thing, not a hard
conclusion. Someday I'll have the time to do a more
comprehensive set of tests to see if I can isolate it - certainly it
flies in the face of logic. I can only confirm that neither amplifier
was overdriven or otherwise distorting overtly.
:cool: |
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