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jay michael

Added more Skrams to my system, Amplifier dilemma

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Happy summer everyone.  Ive got myself stuck in an awkward dilemma looking for a solution. I originally built 4 Skrams using 21sw152 4 ohm drivers and was lucky to come across a right place at the right time deal on a powersoft k10 which has been kicking ass on these subs over the last couple seasons.  This last fall I knocked off another pair of Skrams to add some more headroom and give me more flexible deployment options. The K-10 was already maxed out on a 2 ohms load for the original 4- 21's so in the interim I've driven the additional pair with a prolite 7.5, not ideal I know. I'm looking to square things up and get all the subs running off of the same amplification.  I've been watching for deals on another used k-10, I had hoped due to the covid thing some sweet heart deals would show up but that hasn't been the case. Also being from Canada any powersoft purchase will require stupid shipping costs duties etc and at current prices I'm pretty much looking at 4k Canadian,  which I'm not able to justify.  I have no plans to add anymore subs down the road, the 6 are well balanced with my tops. 

Current options as I see it. Live with the mis-matched amp thing, or sell the K-10 and buy 3 lesser amps that can still drive a pair of 21's each properly. At most I'm feeding the drivers 500 watts, more often 350-400 depending on circumstances.  I like to not give up any quality of sound to what the K-10 can provide and bonus points would be something that could still in an emergency drive all 6 drivers decently if one amp went down.  I would prefer class D to keep the rack on the lighter side.  What do you think? Am a missing a more obvious solution? Budget in the 4-5k range, pretty sure I could get 3k Canadian for the K-10. Any recommendations for amps with good reputation that will happily drive a pair of 21sw152's and sound good doing it? 

Cheers 

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As long as you never push them into clipping, the sound quality between sub amps should be essentially identical.  Likewise, if you never push anything into clipping, then you can probably just keep doing what you're doing right now.

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Ask for a trade on AVS. I'm sure somebody there has 8 Ohm drivers and would prefer 4 Ohm. Make your 6 subs 8 Ohm and run them in parallel, 3 off each channel of the K10 for a ~2Ohm(?) impedance minimum.

Maybe a stupid question, but have you tried running 3 of your current subs parallel on a K10 channel? Ricci ran even lower impedances on the K20 which basically only resulted in sustained output power loss iirc. Maybe try it out and see if it works for you.

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On 7/15/2020 at 2:55 AM, SME said:

As long as you never push them into clipping, the sound quality between sub amps should be essentially identical.  Likewise, if you never push anything into clipping, then you can probably just keep doing what you're doing right now.

Hmm, I had assumed that using different brand amplifiers on the same subs wouldn't be the best idea, but perhaps its not as bad as I had figured. 

 

On 7/15/2020 at 6:49 AM, peniku8 said:

Ask for a trade on AVS. I'm sure somebody there has 8 Ohm drivers and would prefer 4 Ohm. Make your 6 subs 8 Ohm and run them in parallel, 3 off each channel of the K10 for a ~2Ohm(?) impedance minimum.

Maybe a stupid question, but have you tried running 3 of your current subs parallel on a K10 channel? Ricci ran even lower impedances on the K20 which basically only resulted in sustained output power loss iirc. Maybe try it out and see if it works for you.

That had crossed my mind but considering my location in Canada shipping to and from the US is stupid expensive and probably wouldnt make it worth it.  But I think I will throw it out there just in case. Secondly, yes I had seen a few people mention they run their powersoft amps like this but to me it seems risky to me.  Considering I need to rely on my amps sometimes for 3 days straight I would rather run them in more conservative ways.  Thanks for the input. 

 

19 hours ago, klipsch said:

Guessing the Chinese clone option is not one you want to take? 

Well,  it was something I hadn't considered much before but I have been taking some time to research the CVR amps that seemingly have flooded the sound system cultures of the US, Bahamas, Jamaica, France etc.  I've really dug deep into every mention of them I can find online and haven't really found any negative comments about them.  There is lots of very positive comments about performance and reliability.  I've been talking personally with a few users of them and they swear by them.  

That being said, I still have a mental block about investing in something like that, but on the other hand I can get 3-4 of them for the price of 1 used k-10.  One user I spoke with in New York says he's deployed over 30 of them over the last 3 or 4 years and they get worked hard every weekend. He's had to repair three of them, CVR ships him new complete boards for the failed channel for free if within the 2 year warranty, or for 200 US if outside of the warranty,  parts arrive in 3-5 days.  So yeah, I don't know. I think I would still prefer to stay with something more known, but I guess those can fail just as anything else.  My prolite that went down had only been used about 10 deployments. 

Link to an internal view of the cvr d-3002 amplifiers 

 

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I've been running an xbs / sinbosen 240v FP20000Q ($818 USD shipped to door) for only 7 months, but in a home theater seating driving 2 skrams and several sealed stereo integrity HT18s across the 4 channels. Bassthathz in AVS has over a dozen xbs/sinbosen of different models to drive his gear. He seems to be happy with them as well. They are abused for enjoyment to an extent, but not physically with being on tour. 

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Yeah thats the thing I guess. I've got a berry nu3k in my living room and that doesn't really stress me out as if it piles up it only effects me, different story when your in the woods with 500 people haha. 

 

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1 hour ago, klipsch said:

I've been running an xbs / sinbosen 240v FP20000Q ($818 USD shipped to door) for only 7 months, but in a home theater seating driving 2 skrams and several sealed stereo integrity HT18s across the 4 channels. Bassthathz in AVS has over a dozen xbs/sinbosen of different models to drive his gear. He seems to be happy with them as well. They are abused for enjoyment to an extent, but not physically with being on tour. 

And thanks for sharing your experience with your amplifier.  Its not that I doubt that these amplifiers cant be good, there are many examples of first rate quality goods coming out of china.  

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When using two different amps at the same time, there's two things to be mindful of:

(1) Setting gains appropriately.  If you don't need the headroom, you can just gain match them such that all the subs put the out the same amount of sound, but this will cause the weaker amp to overload before the stronger amp.  Another option is to adjust the gains to compensate for the difference in capability so that hopefully all the amps overload at the same time.  That'll get you the most power, but the subs won't be utilized proportionally.

(2) Setting delays appropriately.  This may not be an issue if the amps don't have DSP.  If they do, you may need to delay the signal going to the amp with the lower lag.  This may not be a huge issue, if the lag difference isn't too much, but it's best to match the timings if possible.

Note that it should be possible to address both of these concerns once and reuse the same settings for other venues unless you need to change them for other reasons (like special configurations).

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On 7/17/2020 at 1:12 AM, SME said:

When using two different amps at the same time, there's two things to be mindful of:

(1) Setting gains appropriately.  If you don't need the headroom, you can just gain match them such that all the subs put the out the same amount of sound, but this will cause the weaker amp to overload before the stronger amp.  Another option is to adjust the gains to compensate for the difference in capability so that hopefully all the amps overload at the same time.  That'll get you the most power, but the subs won't be utilized proportionally.

(2) Setting delays appropriately.  This may not be an issue if the amps don't have DSP.  If they do, you may need to delay the signal going to the amp with the lower lag.  This may not be a huge issue, if the lag difference isn't too much, but it's best to match the timings if possible.

Note that it should be possible to address both of these concerns once and reuse the same settings for other venues unless you need to change them for other reasons (like special configurations).

Thank you. Yeah the possibility of one amp having more latency than the other has crossed my mind. They are both non dsp units. Ill need to get a mic on them and do some testing to confirm.  On that note, I'm having trouble coming up with an answer reading through others posts.  When using REW in the info I have gained from the tutorials it sounds like an external sound card is NOT required to use the acoustical timing reference functions for measuring for phase alignment.  I have however came across a user who says an external sound card is absolutely required.  I was messing around with my livingroom system today, made measurements both with my umik 1 wired usb right to my laptop, and then a second time using my external sound device.  Both methods gave me near identical measurements.  A user on a fb group has been discussing how to use the new time alignment features of rew so I've been playing around trying to get a feel for the methodology. I feel like im getting it, but if I cant trust the measurements due to sound card configurations then I'm not helping anything

 

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26 minutes ago, jay michael said:

Thank you. Yeah the possibility of one amp having more latency than the other has crossed my mind. They are both non dsp units. Ill need to get a mic on them and do some testing to confirm.  On that note, I'm having trouble coming up with an answer reading through others posts.  When using REW in the info I have gained from the tutorials it sounds like an external sound card is NOT required to use the acoustical timing reference functions for measuring for phase alignment.  I have however came across a user who says an external sound card is absolutely required.  I was messing around with my livingroom system today, made measurements both with my umik 1 wired usb right to my laptop, and then a second time using my external sound device.  Both methods gave me near identical measurements.  A user on a fb group has been discussing how to use the new time alignment features of rew so I've been playing around trying to get a feel for the methodology. I feel like im getting it, but if I cant trust the measurements due to sound card configurations then I'm not helping anything

 

IIRC a loopback (e.g. Soundcard) is not needed for measuring latency between one speaker and another. 

If wishing to determine latency of specific components with only one speaker then a loopback is needed to determine the time from the sound source to the recorded sound of the microphone from the speaker. 

TLDR - there should be one known source to compare latency to for another source. Between speakers, one speaker becomes the source. Between components, need some way to measure one component as the source to compare against the other measured. (assumes measurement latency will be offset / equal between measurements) 

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7 hours ago, jay michael said:

Thank you. Yeah the possibility of one amp having more latency than the other has crossed my mind. They are both non dsp units. Ill need to get a mic on them and do some testing to confirm.  On that note, I'm having trouble coming up with an answer reading through others posts.  When using REW in the info I have gained from the tutorials it sounds like an external sound card is NOT required to use the acoustical timing reference functions for measuring for phase alignment.  I have however came across a user who says an external sound card is absolutely required.  I was messing around with my livingroom system today, made measurements both with my umik 1 wired usb right to my laptop, and then a second time using my external sound device.  Both methods gave me near identical measurements.  A user on a fb group has been discussing how to use the new time alignment features of rew so I've been playing around trying to get a feel for the methodology. I feel like im getting it, but if I cant trust the measurements due to sound card configurations then I'm not helping anything

If they don't have DSP, then latency is not likely to be a problem.

You don't need an external soundcard unless you need to determine *absolute* latency.  But you don't need *absolute* latency to set up the equipment.  You just need to know the latency *differences*.  If you use a timing reference, the start of the timing reference is specified to be "time 0", and the the delay/latency in all the other measurements is relative to that zero point.  Does this make sense?

You can actually figure out most time alignments even without knowledge of relative latency by trial-and-error measurement of the sources (placed next to each other) playing together with different differential delays applied---the time aligned configuration usually gives the most overall output.  You don't really need precise time alignment information unless you're doing advanced things like summing responses to see how, e.g. a separately measured left and right channel respond when playing together.

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Non-dsp amps will not cause latency issues. The K line dsp, as an example, has a latency of 6ms, which equals 1/3rd of a wavelength of 55,6Hz (below 1/3rd of a wavelength delay, signals will combine well).

Having the same amps is good for flexibility, usability, serviceability and peace of mind. Using different amps will require some work (gain matching in your case) and if you change the setup, it might not be as straight forward as with the same type of amps. If you don't change your setup much and nobody messes with the volume controls, I doubt you'll have any issues with running two different amps.

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On 7/19/2020 at 8:53 PM, klipsch said:

IIRC a loopback (e.g. Soundcard) is not needed for measuring latency between one speaker and another. 

If wishing to determine latency of specific components with only one speaker then a loopback is needed to determine the time from the sound source to the recorded sound of the microphone from the speaker. 

TLDR - there should be one known source to compare latency to for another source. Between speakers, one speaker becomes the source. Between components, need some way to measure one component as the source to compare against the other measured. (assumes measurement latency will be offset / equal between measurements) 

Thank you for clarifying that for me, I will keep on doing what I am doing. :)

 

SME, thanks again for your input.  Phase alignment has been one of the biggest rabbit holes I've fought with over the last few years but I feel I've finally got a reasonably repeatable process that is giving me good results.  

peniku8, yeah I know know its not ideal but with this covid thing im trying not rack up too much dept for new sound gear. If/when things get back to normal Ill figure out something proper.  I dont let anyone touch my gear so not worried about the random factor playing in. 

I did order one of those cvr amps, ill let you guys know what I think. Doing some bush camping in a couple weeks and taking some gear with me so will be able to ring it out a bit. 

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On 7/20/2020 at 11:57 PM, jay michael said:

I did order one of those cvr amps, ill let you guys know what I think. Doing some bush camping in a couple weeks and taking some gear with me so will be able to ring it out a bit. 

Let us know how it goes. On both accounts.

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