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Hearing things I only want to hear ? schematic time

D

donberry

Super Member
Am I just hearing what I want to hear ?
Here is the schematic
hpm-150-schematics.jpg


As my 1st cap swap got more and more hours on it, I thought I was hearing a much boomier bass then I previously had. So I swapped out the 6.8uf obbligato I had put in there with a 7.0 Dynamicap. While it has not had enough hours on it to draw a conclusion, to my ears, I seem to notice a very discernible difference in the bass. Am I just hearing things ?
 
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If you don't have well trained ears, then get some measuring equipment and see if there is a diff.
 
I was just not seeing how that 6.8uf cap would affect the sound of the woofer ? Maybe the speakers are just not in the exact same spot as before......
 
donberry said:
I was just not seeing how that 6.8uf cap would affect the sound of the woofer ? Maybe the speakers are just not in the exact same spot as before......
Click to expand...

Some companys put capacitors in the speakers to act as a manual cross-over, by using a cap with the speaker itself. Epi did this alot...usually with them you get a woofer, a tweeter, and a 10uf cap...thats it. The cap value determines the roll-off or top frequency of that speaker, thats why the other speakers have diffrent values.

Thats only my guess...someone else probably has a solid answer.
 
donberry said:
I was just not seeing how that 6.8uf cap would affect the sound of the woofer ? Maybe the speakers are just not in the exact same spot as before......
Click to expand...

If you're changing the sound of the midrange, it may seem like the sound of the woofer/bass has changed.

However, if you're moving things around this is in effect changing a couple variables at one time and really doesn't make for a good analytical situation, IMO.

I'd expect even a small change in speaker position, listening position, or room arrangement is likely to make a bigger change in the sound than 0.2uF of capacitance in a crossover or the brand of capacitor.
 
if the speaker position has changed, it is a matter of an inch or so as the floor was not marked.
Could just be my hearing, but as I got more and more hours on the obbligatos, I found the bas to be quite boomy and on many songs, found i was actually turning the bass down a click (normal position is flat) and thought about turning it down another but it just seemed so wrong.....so I swapped out the obbligato with another dynamicap. Played the same song i tried right before I swapped them, Stills/Young Make Love to you. Bass back at flat, speaker at most an inch or 2 from where it was, walls no longer rattled on the bass and seemed much more realistic. But, according to the schematic.......I was thinking along the lines of affecting the cutoff somehow, but pretty much same value caps and i would not think the brand would make a difference.
I guess i am just losing my mind, which is not a far fall.
 
Since your mid has 1st order filters, there will be a lot of overlap with the woofer and tweeter. So you're probably not imagining things. Obbligatos have a nice tone, I've used them in speaker crossovers before, but never on a mid or woofer though. If you're willing to try something different, check out Claritycaps ESA's. They're a great sounding cap for the money.
 
Face - I have read really good things about the claritycaps. I was ordering the obbligatos for a pair of magnepan and thought I would try some in the HPM-150 while I was at it. So happened the other caps that went to the maggies were the Dynamicap 7.0uf, so since I had them on hand, just swapped those in to see if it was that.
I thought I noticed an immediate improvement but the schematic was pointed out to me, so then started wondering if I were just imagining things - yet I felt it was tough to imagine turning my bass down to -1 and now it is back to flat and still does not seem as boomy.
When I first installed them, I was actually pretty wowed as I thought I had gained more clarity and some sweeter mids and highs (used an auricap for the 3.9 and a dynamicap for the 3.0), but as they got quite a bit of hours on them, just seemed I was noticing a more boomier bass that did not seem so realistic and then found myself turning the bass down to -1, which I have never done before
I have them playing now (paranoid - black sabbath), cranked up pretty good and the tones are back to flat and do not have that boominess to them anymore - or, I am just hearing what I want to hear.
I will try the claritycaps as I need the dynamicaps back for my maggies, tho I am pretty happy at the moment so if they still sound like this in about 100 hours, I may just leave them and try some claritycaps in my HPM-100 (I leave the stereo on for about 10 hours a day while wife is at work, so 100 hours is less then 2 weeks)
 
donberry said:
Am I just hearing what I want to hear ?
Here is the schematic
hpm-150-schematics.jpg


As my 1st cap swap got more and more hours on it, I thought I was hearing a much boomier bass then I previously had. So I swapped out the 6.8uf obbligato I had put in there with a 7.0 Dynamicap. While it has not had enough hours on it to draw a conclusion, to my ears, I seem to notice a very discernible difference in the bass. Am I just hearing things ?
Click to expand...

Did you have to remove the woofer to do the mods? If so, check:

1- That the driver leads are correctly polarized.

2- That the driver is seated and sealed correctly.

3- That the woofer was inserted with the same rotational orientation as before. (EG- it is not rotated by 90, 180 or 270 degrees, in the case of a 4-hole flange.)

4- Have you double-checked the polarities of the reconnected speaker boxes?

As was noted earlier in the thread, a change in the mids can be audible as a change in the bass, for various reasons. But, I really wouldn't expect much from the cap change you made, unless one of the caps has a very high (ie-defective) ESR.

-k
 
Just to show you, going from a 6.8uf valued cap to a 7.0uf doenst change much when it comes to frequency response. I modeled just an 8ohm resistor as a load so its not perfect but you get the idea.

I would def check polarity since the Mid and the Super Tweeter are both reversed by design.

Here are the quick plots of that section of the xover.
I did a sweep from 2k to 20k on the first and then 4k to 10k on the second to show how little the difference is.
sansui1.jpg

sansui2.jpg
 
Just for kicks I did the whole thing. There is alot of overlap in the freqs but its also delegated by the freq response of the speaker it self.
sansui3.jpg
 
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