AudioNervosa

Systemic Development => Psycho-Acoustics => Topic started by: jimbones on December 08, 2014, 08:23:56 AM

Title: Bass acoustic issues
Post by: jimbones on December 08, 2014, 08:23:56 AM
Professor,

See my room layout attached :-P
Title: Re: Bass acoustic issues
Post by: richidoo on December 08, 2014, 08:51:45 AM
I started a new thread for this.

See previous posts related to this thread, starting here:

http://www.audionervosa.com/index.php?topic=5284.msg66764#msg66764

Sorry I can't move them into this thread.
Title: Re: Bass acoustic issues
Post by: richidoo on December 08, 2014, 08:52:50 AM
You are a visio master  8)

Jim, what is the actual problem you are having with the bass?

Title: Re: Bass acoustic issues
Post by: richidoo on December 08, 2014, 09:13:20 AM
(http://www.audionervosa.com/index.php?action=dlattach;topic=5289.0;attach=6120;image)
Title: Re: Bass acoustic issues
Post by: jimbones on December 08, 2014, 09:23:20 AM
Boomy. I haven't measured it yet but if I had to guess around 45-50 hz. I will have to update the visio file it is a bit outdated.
Title: Re: Bass acoustic issues
Post by: jimbones on December 08, 2014, 09:32:36 AM
updated visio
Title: Re: Bass acoustic issues
Post by: tmazz on December 08, 2014, 01:00:55 PM
Jim, have you ever thought of  blocking off that hallway the leads back to the stairs? Between the hall and the turn around up the stairs I wounder if it isn't forming some kind of resonant cavity. You could try with just a scrap piece of plywood or sheetrock and if it helps put in a permanent door.
Title: Re: Bass acoustic issues
Post by: richidoo on December 08, 2014, 02:09:01 PM
That long hall is the stairway, right? The room width and the hallway are both 22 feet, which is 25Hz fundamental, 50Hz 2nd harmonic. So the hallway could have something to do with it, especially since your ears are parked right at the halfway point, max amplitude of the resonance.  See attached picture of modecalc mode prediction. 

You could improve your S/N in the midrange by making a fake wall between the side room and your listening area. But you get used to it, it's not a huge deal unless you are really picky about clarity in midrange.

Is the visio all concrete walls or is there other rooms? Finished ceiling? Insulated? Height?

I like the position of the sub in the previous visio, closer to you. The sub should always be closer to you than the main speakers so that you can time align them with the sub delay (phase) control. Out of alignment sub will make the bass sound blurred.

Depending on how low you crossover a good place for the sub might be right behind your chair.  :shock:  You increase the S/N ratio a lot having it close. The reflections are delayed and much quieter which cleans it up a lot. You can turn it way down in volume so it won't generate as strong modes in the room, and it is closer than the mains so you can delay it to align perfectly with the mains. And it is still out of the way. If you cross it above 80Hz then it must be near the speakers because it starts to locate for most people at 100Hz.  You may want smaller 8" separate stereo subs at the speakers for >50Hz, and a big sub closeup for <50hz.

See if you can do a FR sweep with that omnimic? With both speakers playing and the sub turned on... as a baseline, or is it bass line?
Title: Re: Bass acoustic issues
Post by: jimbones on December 08, 2014, 03:32:47 PM
Ok so there's a lot of info and I'll try to handle a few bites at a time. The hallway leads to a stair that isn't shown. It is a 180 degree turn and the up the stairs. I can wall that hallway off if I have to, maybe put a solid door.

The walls are sheet rock with knotty pine on the bottom half. The ceiling is 2x2 drop with Roxul between then joists and diffusors in selected areas. BTW I do have a walled off section (Plywood) just above the record cabinet that seperates the 2 rooms.  More to come.  :lol:
Title: Re: Bass acoustic issues
Post by: jimbones on December 08, 2014, 03:35:12 PM
BTW my sub only has a phase switch and is not continuously variable.  :( ceiling height is NOT 8 ft I'll get exact measurements
Title: Re: Bass acoustic issues
Post by: richidoo on December 08, 2014, 05:38:09 PM
Ceiling height is not critical. The height to the hard plane above the joists is what matters. The drop ceiling is invisible to LF.

Low bass will move through sheetrock walls pretty easily but it will reflect on concrete. Mid and upper bass has varying reflectivity from stick walls.

The sub position and phase stuff is pretty much a different topic. Let's see about the acoustics first.
Title: Re: Bass acoustic issues
Post by: jimbones on December 09, 2014, 06:14:43 AM
One other idea since it is quick and wont cost me anything is to put a bass trap in that ling hallway and see if it changes anything. Getting more bass traps can't hurt.
Title: Re: Bass acoustic issues
Post by: tmazz on December 09, 2014, 06:39:13 AM
I want to be there when you tell Maria that the final step to prefecting you speaker design will be to buy a new house to put them in.   :duh

(It will be easy to spot me. I'll be the one standing off to the side with the First Aid kit.  :rofl: :rofl:)
Title: Re: Bass acoustic issues
Post by: jimbones on December 09, 2014, 07:25:34 AM
ha ha. You're not kidding. I am "considering" the idea of building a dipole bass unit to go down to 80 hz, prefer  without equalization. Even at 80 hz it would be quite large I am thinking. Might have to reconsider. BTW if I did move to another house yes it would have to be "audiophile friendly"
Title: Re: Bass acoustic issues
Post by: richidoo on December 09, 2014, 08:55:51 AM
Dipole does alleviate a lot of bass problems. When I used Quads the bass was very clean.  I would like to try dipole again.

Rythmik/GR is probably the best system for low distortion OB bass. It can play low and loud and clear with slam, like an EQ'd low Q driver.

Without feedback or EQ you will need high Q drivers to get LF extension and SPL, and that requires sacrificing some detail and control, so it pairs best with warmer musical type midrange driver. Hawthorne and AE make good quality OB drivers for passive crossover with no EQ.
Title: Re: Bass acoustic issues
Post by: jimbones on December 10, 2014, 06:15:07 PM
OK so the ceiling is 7'2" to the bottom of the joists and 6'10" to the ceiling tile.

I never used Omnimic to do room response so I tried several different measurements. see attached we can discuss once we take a look.

Title: Re: Bass acoustic issues
Post by: richidoo on December 10, 2014, 07:39:07 PM
Disregard my last post, I deleted it.

I was reading the graphs you posted as FR graphs, but they are actually decay graphs. Can you post the frequency responses from those two sweeps near sub and listening chair?  Thanks
Title: Re: Bass acoustic issues
Post by: richidoo on December 10, 2014, 08:02:31 PM
Looking at the 3rd plot you have there labeled Spectrum, that is kinda like RTA frequency response.

It shows a bump at 25Hz, which corresponds to the fundamental resonance of the room width 22feet, but that also contributes 2nd harmonic at 50Hz, which adds to the 53Hz 3rd harmonic of the long hallway. The big bump starts at 70 and stops at 140, those are the fundamental and 2nd harmonic of your 8 foot ceilings, but the long hallway also has harmonics with 70 and 140. Ceiling/floor have the largest area of parallel surfaces, so it is often a problem. That's what I think you are being annoyed by. The 25Hz bump is not as sensitive to our ears, and it's only +10. You can EQ that easily.  The ceiling bounce is the trouble, I think.

How thick insulation do you have in the drop ceiling? The whole thing drop ceiling is insulated or just above your seat?

The ceiling height is measured to the top of the joists where the upstairs floorboards reflect sound back down. So 8'-2" height, I'm assuming 12" joists right?

Forget the previous measurements. Can you post unsmoothed FR graphs of these three sweeps:
1. mic at listening spot, sweep as is for baseline.
2. Without moving the mic, sweep with sub turned off
3. Without moving mic, sub still off, stuff/seal the ports on your main speakers' woofers with small towels, etc.

Thanks
Rich
Title: Re: Bass acoustic issues
Post by: jimbones on December 11, 2014, 05:25:58 AM
See response embedded Thanks professor!!  :thumb:

Looking at the 3rd plot you have there labeled Spectrum, that is kinda like RTA frequency response.<it is>

It shows a bump at 25Hz, which corresponds to the fundamental resonance of the room width 22feet, but that also contributes 2nd harmonic at 50Hz, which adds to the 53Hz 3rd harmonic of the long hallway. The big bump starts at 70 and stops at 140, those are the fundamental and 2nd harmonic of your 8 foot ceilings, but the long hallway also has harmonics with 70 and 140. Ceiling/floor have the largest area of parallel surfaces, so it is often a problem. That's what I think you are being annoyed by. < agreed>The 25Hz bump is not as sensitive to our ears, and it's only +10. You can EQ that easily.  The ceiling bounce is the trouble, I think.

How thick insulation do you have in the drop ceiling? <3 1/2 in Roxul> The whole thing drop ceiling is insulated or just above your seat? <90 % of the area has Roxul>

The ceiling height is measured to the top of the joists where the upstairs floorboards reflect sound back down. So 8'-2" height, I'm assuming 12" joists right? <I think 10in>

Forget the previous measurements. Can you post unsmoothed FR graphs of these three sweeps:
1. mic at listening spot, sweep as is for baseline.
2. Without moving the mic, sweep with sub turned off
3. Without moving mic, sub still off, stuff/seal the ports on your main speakers' woofers with small towels, etc.

<Yes except my floor standers are acoustic suspension bass>
Thanks
Rich
Title: Re: Bass acoustic issues
Post by: richidoo on December 11, 2014, 06:20:42 AM
<Yes except my floor standers are acoustic suspension bass>

Great! That's ideal for blending with a sub.

<3 1/2 in Roxul> 
<90 % of the area has Roxul>
<I think 10in>

OK, so ceiling height is exactly 8 feet, fundamental is 70Hz.  The floor is concrete, right? The wall at the end of the hallway is concrete too?

If the ceiling is the cause of the 70-140Hz bump, you may need to add thicker absorption in the ceiling.

But lets see the new scans without the sub.  Since your mains are sealed, they will not reach down low enough to ring the long hallway, but the ceiling ringing would remain. Their harmonics overlap, so it should be interesting.
Title: Re: Bass acoustic issues
Post by: jimbones on December 11, 2014, 04:23:52 PM
measurements attached
Title: Re: Bass acoustic issues
Post by: richidoo on December 11, 2014, 04:55:52 PM
Nice!! That is a nice looking FR!

Looks like you're crossing the sub at 40Hz, 4th order. Your avg sensitivity (only on this chart) is 90-95ish. So you don't need a sub, although you might like more punch than flat allows. You must have large woofers on the mains? You named them Lambda so I guess packing something under the hood!

Two things worth looking into: The broad peak at 90Hz and the narrow dip at ~170Hz?  Could the narrow notch be driver cancellation? Are your driver polarities correct? 4th order crossover uses same polarity while 2nd order uses opposite polarity. Kinda low in freq for comb filtering, but the interval is right, dunno. Fortunately it is narrow so you probably won't notice it anyway.

The peak at 90 is probably what is bothering you. What might cause that? Hmmm..

edit: I don't see any standard room modes based on the room dimensions that could cause the peak at 90Hz. 90Hz is relatively clean frequency. It could be oblique modes bouncing around diagonally?

Next thing would be to take a couple more scans from different places around your listening room portion of the basement, to see what happens to the 90hz mode in different positions. Try one with mic moved 3 feet forward toward the speakers. Another one from dealers choice?
Title: Re: Bass acoustic issues
Post by: jimbones on December 12, 2014, 05:02:30 AM
Yea, I have 10 inch Daytons RS270's in the mains. Funny, the bass waas a bit cleaner and controller when I had my Aragon amp, but there is more basas with the Modwright. Also a spdif cable change added more low end so now there's actually too much of a good thing  :duh.

The mains (theoretically) roll off at around 48hz. They seem to go deeper. I am using dipoles above 275hz but that would not explain the cancellation would it?
in a 3 way system I think my XO are all 2nd orders, polarity is +, -, -. (I know the tweeter s/b + but it sounds better -)
Title: Re: Bass acoustic issues
Post by: richidoo on December 12, 2014, 06:49:18 AM
You got a good handle on it Jim. Different amps have different sound. This is why pro audio guys think we are crazy. But the output transistors all sound different, as do their circuits. Cables, well, you know the deal with that.

Rolling off at 48Hz means they are -3dB at that freq. Sealed means they roll off at 12dB per octave, so they are only -9 down at 24Hz. In addition, the room, especially a bass bowl like concrete basement reflects some (or a lot) of that bass back into the room and boosts the bass by 12dB/oct with dropping freq, matching the driver rolloff. You can get flat FR as low as you want if you choose the right diameter bass driver to match the size of your room. Seems like you got it about right with the 10s.

Definitely run a couple more sweeps of the room in different places. If you see that 90 Hz peak not going away or changing freq then you know it's coming from your system, not the room.  When you move the mic the room modes will rise and fall and different modes will make other freqs come up and down. When things stay the same despite moving the mic, then the EQ is being played into the room. If you find that it is a room mode or combination of them, the easiest thing to try since it is only 10dB bump is to move your speakers around. Measure once to establish baseline, then  move them 1 foot forward toward the listener and sweep again without moving the mic at all. If that changes the bump significantly then you can work on positioning the speakers. I recommend trying the Master Set procedure. It is described well on Audiocircle by Stephen Harr. It works pretty well to flatten the bass response.
http://www.audiocircle.com/index.php?topic=64320.0
http://www.audiocircle.com/index.php?topic=65908.0

If there's any chance you think the extra bass could be coming from the system, you should try applying EQ, as an experiment, to see if things get better. The easiest way I know to do that is to install trial JRiver, and play some tunes through their parametric EQ module. You should be able to measure the room on the same computer while playing tunes from JRiver, but you'll know by ear if it's working.

You can rip a couple tracks to the hard drive, play them through the headphone jack to your preamp. Hifi doesn't matter here, we're just thinking about the rough bass EQ which will be close enough through the PC. Any headphone jack will be well within 2dB correct FR.

You have mentioned aversion to applying EQ, but if the system is making the bump, then there is already EQ in the system and you are just correcting and removing what shouldn't be there. I agree that Behringer DEQ2496 shouldn't be in anyone's audiophile system, but there are many other ways to get the job done that don't hurt the SQ at all. Jriver and omnimic together will help you figure out what actually works, before you make a corrector.

What is the width of your woofer front baffle? Did you apply baffle step correction before your bass to mid crossover?
Title: Re: Bass acoustic issues
Post by: tmazz on December 12, 2014, 07:54:32 AM
......This is why pro audio guys think we are crazy.

You mean we're not crazy????  #-o

I don't think you will ever get my wife to agree to that.  :rofl:
Title: Re: Bass acoustic issues
Post by: jimbones on December 12, 2014, 07:59:53 AM
See response embedded. Mucho Gracias

You got a good handle on it Jim. Different amps have different sound. This is why pro audio guys think we are crazy. But the output transistors all sound different, as do their circuits. Cables, well, you know the deal with that.

Rolling off at 48Hz means they are -3dB at that freq. Sealed means they roll off at 12dB per octave, so they are only -9 down at 24Hz. <wouldn't that be -15?>In addition, the room, especially a bass bowl like concrete basement reflects some (or a lot) of that bass back into the room and boosts the bass by 12dB/oct with dropping freq, matching the driver rolloff. You can get flat FR as low as you want if you choose the right diameter bass driver to match the size of your room. Seems like you got it about right with the 10s. <maybe 8's are more appropriate>

Definitely run a couple more sweeps of the room in different places. If you see that 90 Hz peak not going away or changing freq then you know it's coming from your system, not the room. <I do seem to remeber walking around the room with the mic and not seeing the Fr change all that much but I need to do it again> When you move the mic the room modes will rise and fall and different modes will make other freqs come up and down. When things stay the same despite moving the mic, then the EQ is being played into the room. If you find that it is a room mode or combination of them, the easiest thing to try since it is only 10dB bump is to move your speakers around. Measure once to establish baseline, then  move them 1 foot forward toward the listener and sweep again without moving the mic at all. If that changes the bump significantly then you can work on positioning the speakers. I recommend trying the Master Set procedure. It is described well on Audiocircle by Stephen Harr. It works pretty well to flatten the bass response.
http://www.audiocircle.com/index.php?topic=64320.0
http://www.audiocircle.com/index.php?topic=65908.0

If there's any chance you think the extra bass could be coming from the system, you should try applying EQ, as an experiment, to see if things get better. The easiest way I know to do that is to install trial JRiver, <I already used a paid version MC19 in my system. I didn't even use the equalizer although I aassume that is only when playing hires music files from my laptop> and play some tunes through their parametric EQ module. You should be able to measure the room on the same computer while playing tunes from JRiver, but you'll know by ear if it's working.

You can rip a couple tracks to the hard drive, play them through the headphone jack to your preamp. Hifi doesn't matter here, we're just thinking about the rough bass EQ which will be close enough through the PC. Any headphone jack will be well within 2dB correct FR.

You have mentioned aversion to applying EQ, but if the system is making the bump, then there is already EQ in the system and you are just correcting and removing what shouldn't be there. I agree that Behringer DEQ2496 shouldn't be in anyone's audiophile system, but there are many other ways to get the job done that don't hurt the SQ at all. Jriver and omnimic together will help you figure out what actually works, before you make a corrector.

What is the width of your woofer front baffle? Did you apply baffle step correction before your bass to mid crossover? <I think 11 + 3/4 side panels with 30 degree bevel so 12.5. I don't have baffle step correction because it occurs at or near the XO point>
Title: Re: Bass acoustic issues
Post by: jimbones on December 12, 2014, 08:06:05 AM
I know I'm not crazy because my therapist told me so!

 ](*,) ](*,)




......This is why pro audio guys think we are crazy.

You mean we're not crazy????  #-o

I don't think you will ever get my wife to agree to that.  :rofl:
Title: Re: Bass acoustic issues
Post by: richidoo on December 12, 2014, 10:18:41 AM
See response embedded. Mucho Gracias

<wouldn't that be -15?>  Yes. I need common-core refresher!  :duh

<maybe 8's are more appropriate>  Nah, you have a big room, and you're flat in bottom octave. The peak is not related to driver size. The reason woofers rolloff is because they are too small to play any lower. This is called acoustic impedance = the ability of the cone to grip the air. Air just spills out over the edge of small cones moving big excursion at a slow speed (LF.) At higher speed (HF) the air can't escape out of the cone quick enough, so it gets moved. 

<I do seem to remeber walking around the room with the mic and not seeing the Fr change all that much but I need to do it again> OK. That's really good, let's hope that pans out. The best thing would be for this problem to be in your system, cuz that's easy to fix.

<I already used a paid version MC19 in my system. I didn't even use the equalizer although I aassume that is only when playing hires music files from my laptop> It will EQ any file that you play, and the DSP is 64 bit.  :thumb:  Create a notch filter at 90db  -10dB amplitude and play with the Q of it to adjust the width. Higher Q makes a narrower notch. 

<I think 11 + 3/4 side panels with 30 degree bevel so 12.5. I don't have baffle step correction because it occurs at or near the XO point>

The BSC formula is F3 = 380 / baffle width (feet), so your filter should knee at 380, but it must be done by ear to suit the room, etc. A project for another day!  But now we know that incorrectly applied BSC is not the cause of the too loud bass.
Title: Re: Bass acoustic issues
Post by: tmazz on December 12, 2014, 12:13:43 PM
I know I'm not crazy because my therapist told me so!

 ](*,) ](*,)




I don't need a therapist to tell me that. I keep hearing it from the voices in my head.  :shock:
Title: Re: Bass acoustic issues
Post by: jimbones on December 12, 2014, 04:33:50 PM
<<Two things worth looking into: The broad peak at 90Hz  and the narrow dip at ~170Hz? Could the narrow notch be driver cancellation? ((doubt it the XO is close to 300hz))Are your driver polarities correct? 4th order crossover uses same polarity while 2nd order uses opposite polarity>>

Looks like the 90 hz changed as I moved into the plane with the speakers. when I move to the wall the 170 moves to 220hz.
Title: Re: Bass acoustic issues
Post by: rollo on December 13, 2014, 06:53:17 AM
   How about you try a passive high pass inside the amp say cut off at 73HZ. That will relieve the amp and drivers for frequencies not required. A huge difference sonically. Then bring up the sub with its crossover until your measurements are correct.
    You will most likely hear the best result as you measure. The rythmic plate amps have an excellent control panel to fine tune.
    to date the most accurate and real sounding bass was produced by Dannie Richies open baffle subs using rythmic amps and a high pass in the amp.


charles
Title: Re: Bass acoustic issues
Post by: jimbones on December 13, 2014, 11:27:04 AM

Yes Charles. I have those RCA HP filters I think they are tuned at 50 or 60 hz. Although I remember with my former amp they added a bit of grunge.  I can always try them again as it costs me nothing. I am VERY interested in building the woofers you mention. I would like to operate them up to 275 hz if possible.


   How about you try a passive high pass inside the amp say cut off at 73HZ. That will relieve the amp and drivers for frequencies not required. A huge difference sonically. Then bring up the sub with its crossover until your measurements are correct.
    You will most likely hear the best result as you measure. The rythmic plate amps have an excellent control panel to fine tune.
    to date the most accurate and real sounding bass was produced by Dannie Richies open baffle subs using rythmic amps and a high pass in the amp.


charles
Title: Re: Bass acoustic issues
Post by: jimbones on December 13, 2014, 08:31:30 PM
So here's the good and the bad. The HP filters definitely cleaned up the bass which there was a bit too much. The Bad is that the sound is not as pristine as without them. Now I am going to assume that in these little rya thing-a-ma-jigs do not contain great caps. I could make my own HP filters using really hi quality components. I think I'll e mail Dan Wright for the proper values.
Title: Re: Bass acoustic issues
Post by: richidoo on December 14, 2014, 07:56:01 AM
Oooh! Nice! I'm glad it made an improvement. Good call rollo!

You don't need Dan Wright for this. I googled the input impedance is 20kOhms.

Looking at your sweeps I think the starting freq for the high pass filter should be 200Hz, but you'll want to swap caps to find the best value. 

Use this calculator to find the starting cap value:
http://www.diyaudioandvideo.com/Calculator/XOver/
Impedances are 20000 (the input impedance of your amp)
200Hz gives  .04uF for the high pass cap
Ignore the low pass info

Schematic diagram for first order high pass filter:
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html
(http://p10hifi.net/TLS/tech/filters/pllxo/hipass.gif)
Your amplifier is R2. Just put the cap in series with the line signal. Maybe you can mod the RYA adapters with these caps, just let the caps hang out, you don't need the adapter covers. If you solder plain wires into the adapter )or cut out the old cap, then you can just clip lead the new caps onto the old leads for easy swap and experiment. You'l want to make it fast to switch freqs when deciding what value.

This cap will make the freq ~175Hz  Link (http://www.mouser.com/ProductDetail/Vishay-Roederstein/MKT1813347255/?qs=sGAEpiMZZMv1cc3ydrPrF6ZDFxbqwGM%2fJy%252bCaSYXqo4%3d)

Buy pairs of .01uF, 022uF and .047uF. That will give you a variety of possibilities to try different frequencies by paralleling them together. Paralleling adds capacitor value. Increasing cap value reduces the freq. If you want to try very low freqs like 50Hz then also buy a pair of .1uF. Buy the lowest % tolerance available, but don't sweat it. Link (http://www.mouser.com/Passive-Components/Capacitors/Film-Capacitors/_/N-9x371Zscv7?P=1z0wpzoZ1z0wpseZ1z0wpt1Z1z0wqus&Keyword=MKT1813&FS=True)
They offer 1st class mail for cheaper shipping, as does digikey

These caps sound very good, I use them in all my line level stuff. But if you want to upgrade to VCaps/Duelund/Jupiter/ClarityMR  later you'll know what value works.
Title: Re: Bass acoustic issues
Post by: jimbones on December 14, 2014, 08:02:29 AM
OK so those are Vishay caps. They say they are film but not much info beyond that. I guess they could be poly etc?

Title: Re: Bass acoustic issues
Post by: richidoo on December 14, 2014, 08:07:33 AM
MKT=polyester
MKP=polypropylene
Title: Re: Bass acoustic issues
Post by: jimbones on December 14, 2014, 08:40:40 AM
Well, Im not confident I'll be able to take apart the Harrison Labs filters. They may even be potted. I have other options such as taking a spare Interconnect and modding it or opening up the amp and putting it on the input jack. (bad thing about that it is not easily removable like a interconnect).
Title: Re: Bass acoustic issues
Post by: richidoo on December 14, 2014, 09:04:29 AM
You want the cap out in the open to swap caps.

Or you can determine the best freq using JRiver. Make a 6dB high pass filter in PEQ module of the DSP section. Adjust freq to taste.

Once you decide on a freq, then calc the cap and make up a nice RCA adapter cable with Switchcraft 3502 and 3503 connectors. They are high copper brass and inexpensive.

Title: Re: Bass acoustic issues
Post by: rollo on December 19, 2014, 08:20:01 AM
  The Harrisons are designed for car audio. OK but we can do better. Attach a lead from the wire of the RCA input and one from wire going to board. This way you can try different caps. The cap choosen will have a big affect. Do not cheap out as the values are small.


charles
Title: Re: Bass acoustic issues
Post by: jimbones on December 19, 2014, 06:00:26 PM
  The Harrisons are designed for car audio. OK but we can do better. Attach a lead from the wire of the RCA input and one from wire going to board. This way you can try different caps. The cap choosen will have a big affect. Do not cheap out as the values are small.


charles

I agree that because the values are small it won't cost much, I just prefer not to dick around with the inside of my amp since I just bought it. Not that I don't have the confidence I'd like to do something external so I can change it out easily. More to come.....