peniku8

11 minutes ago, klipsch said:

There's the even cheaper route as well https://www.parts-express.com/dayton-audio-pss555-8-21-pro-subwoofer-with-45”-voice-coil-8-ohm--295-050

Yea, which would be more expensive than a 21DS115 here. US imports are crazy expensive in Europe.

Seen this a few days ago, but it didn't quite impress me. Especially since it'll be more expensive for me than a 21IPAL and well.. ferrite magnets are unattractive to me.

Afaik Ricci had two of their older models, which were identical to some Crown amp.

I think you can combine multiple of those newer amps to gain even greater power. But it‘s pretty apparent that they‘re not designed with moving around in mind 

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.

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.

8 minutes ago, SME said:

I'm not a fan of operating long-term with the chassis open.  The chassis may establish necessary air currents for certain components.  There's also the risk of foreign objects getting in and shorting things.  And also if something goes *poof*, the chassis makes it much less likely that your house will catch fire.

 

Good luck to you whatever you decide.

That's why I suggested making a new top plate if he doesn't want to cut to original one. The layout of the heatsinks make cooling like that really easy and efficient. The fans just need to touch the fins to turn the heatsinks into closed-off paths for the airflow. If theres too much of a gap, the fans will draw air from the sides and cooling won't be efficient.

I'm not 100% sure about the cooling system in the K line, as the radial fans don't give a great insight on air flow, but if you took those out and mounted a few 80mm fans to the heatsinks (with the fans blowing air up), leaving the top panel off, or better: making cut outs for the fans, the cooling would likely be better and very quiet. If you don't want to cut holes into the top panel, make something out of acrylic for example. That guides the cold air through the components and the hot air ventilates through the fans in the top.

Keep in mind that this solution will require additional dust filters at any point where air can be sucked into the amp (like the holes in the back after removing the og fans).

I measured the idle power draw and it looks like it went up to 160W (from 115). I can only measure in 0.1A steps, which is 23W, so the possible difference ranges from 23W to 69W. Not really a good sign, but it's not a huge amount either, so I'm not necessarily concerned about it. Their 4 channel amp draws almost 200W in idle. One reason for me to not switch the TSA1400 in the theater back out for the FP13000.

15 minutes ago, SME said:

This has all been quite interesting to follow.  I'm going to take a wild guess that the mixture of transistor types on the old board was "on purpose", albeit maybe as a last-minute hack or tweak for some other problem.  Hopefully the new revision is a lot more robust.

Well the PSU blew up during testing. I only had to replace the amp boards because I damaged them by accident while trying to repair the PSU.

If the mix was on purpose, why use different amounts on both channels?

I also have the feeling that the amp gets hotter in idle now. So either the heat transfer from the transistors to the heat sink is better now or something else is the problem. I also reversed the fan mod I did and let the fans run full tilt now. I‘ll have a look at the idle power draw and see if it‘s higher than the ~150w it was before.

Either way, the bad gut feeling will now never subside when I bring that amp to a gig. I don‘t have any use for it at the moment anyways, so I might just sell it and call it a day.

Quick update on the Sanway: I've recieved two replacement amp boards they sent me for 300$ including shipping. Amp is operational again.
The amp boards which I had were version 2, the new ones are version 10. They now also use the same type of transistors throughout.

21 minutes ago, kipman725 said:

The 1kv to ground sounds very weird as even if the heatsink was live on purpose you wouldn't expect 1kV to be generated anywhere in the amp.  Mix of output transistors is a very bad idea as they won't share current effectively.  On the plus side this is making me very certain I don't want one of these amps in my life

I ordered two replacement modules, will see if the current ones are the same. This amp is 7 years old after all.

4 hours ago, Kyle said:

Hard to tell what that might be, best to return it if you can? The noise may be coming from the motor or voice coil. The phase plug won't likely be making any actual noise itself, but any number of things could be wrong with that driver, its very hard to tell sometimes what exactly it is.

 

 

Yea I returned it. With the phase plug I was just refering to the general direction. I had 12 woofers in series and it was clear that this one made noise well before reaching Xmax and it was about 5db earlier compared to the other woofers.

This is so annoying. I was just way too curious to see if I could improve the amp's performance by adding those components and now I caused 150$ damage again.

Well, heres more random info on the PSU: when both amp stages are disconnected, the PSU hold over 200V for an hour. I used a light bulb to quickly drain it. When it's down to 0.1V, it takes about 10 seconds to climb back to 2V. I immediately connected the 230V light bulb after I powered the amp off, when the PSU was still at around 350V from positive to negative. It was a 30W light bulb or smth, it lit up brightly for a second and the light faded completely after some 20 seconds. Very convenient way when you're working on this kind of stuff.

Seems like this amp is haunted by Hoffmann's Law. I'm not sure why but the modifications I made (wich was adding the two missing resistors and transistors) broke the amp stage. The fuses melted so I removed the components again but it's still inoperational. Welp, now the amp doesn't work at all anymore, since both output stages are broken. I'm guessing that it's a relatively minor thing, but I'm not the one to track down a broken component and I'm fairly certain that getting it fixed will be more expensive than the 150$ for the replacement board.

What confused me even more was the seemingly random choice of output transistors, as two different models were actually used in the amp.

One output channel has an even distribution of both types, while the other one has 5 of one type and 9 of the other. Both are the NPN type.

https://www.onsemi.com/pub/Collateral/NJW0281-D.PDF

https://www.onsemi.com/pub/Collateral/NJW21193-D.PDF

Looks like the 21193 is a bit better. I'll solder two from the broken pcb to the working pcb to "upgrade" the FP-13000 to Fp-14000 on the output stage. It might make a slight difference into lower impedances. 14 vs 16 transistors is still a decent upgrade.

I somehow feel like this is bad design or something isn't working as it should. The 4 transistors I replaced in the PSU, which all broke after about 2 minutes of 4KW output generate a humongous amount of heat even in idle.

The heatsink seen below reaches 80°C (176°F) in idle and SOMEHOW I measure over 1KV from heatsink to ground and when I touch it with the thermo sensor I see small sparks. What is going on here??

Interesting, I also had a problem with one of the 14 Dayton woofers I recently got. Very similar noise, just that I was testing at 20Hz so the "clicking" was slower. The issue doesn't seem to come from the surround on the Daytons, more like the noise comes from the phase plug (those woofers have a solid phase plug in the center instead of a dust cap).

25 minutes ago, Bobby said:

I can’t switch the drivers no more, I will stay with the um’s and the Magnums, that are pretty sensitive drivers and give it a shot; I hope to integrate them with the Um’s and split the frequency range in two, say 5-50Hz to the Um’s and 50-120Hz to the Magnums.

Ported subs are easy to integrate if they are the lowest playing speakers in the system. If you have ported subs and want to run something below that (like sealed or other deeper ported subs), you'll have a hard time on doing so. FIR filtering might be the only solution, at the cost of delay and ringing. But since that's not the case you won't have to worry about that.

You might wanna ask this question on AVS again, but unless your cab is severely mistuned, the issues you‘re hearing are likely room issues.

I have no experience with the um-18, but apparently it‘s also pretty capable in the mid-bass region. I‘m not sure if dropping those drivers in sealed cabs would yield your desired improvements.

I have seen other people using (multiple) um-18s seeking for better misbass performance, which makes me wonder why not go for the 21ds115 or similar instead. I know in the states they‘re similarly priced and you‘ll lose a bit of deep bass (displacement), but you‘ll gain a lot of sensitivity.

If those magnum drivers are high sensitivity drivers, I‘d give them a shot. Should work rather nicely in sealed cabs.

What other subs are you using in your setup, for which you‘re hoping for better integration?

What‘s the purpose of those caps? DC blocking? Wouldn‘t it possible to just short em instead then?

1 hour ago, SME said:

Is it really that simple?  My first instinct is that it's different because the energy storage mechanism is a bit different.

https://en.wikipedia.org/wiki/Capacitor#Energy_stored_in_a_capacitor

You can see that the charge is proportional to C*V while the stored energy is proportional to C*V². If it wasn't "that simple", these formulas would not be that simple either

11 hours ago, SME said:

That 50% figure sounds impressive, but one question I'd have is how much charge does the capacitor effectively store at that voltage?  I assume it's probably a lot less than it stores when fully charged, but the Wiki article doesn't clarify this point.

I mean, I fairly routinely discharge tens of thousands of volts by simply touching things around the house, but this static electricity carries so little charge that it's essentially harmless to me (but not necessarily my equipment).

The stored energy is the capacitance times voltage squared, so at 50% voltage the cap will be 25% charged. Double the voltage and you quadruple the ‚power‘, seems familiar, doesn‘t it!

Static electricity doesn‘t kill you because your capacitance is very low, so you only store a minuscule amount of energy. 

@SME And luckily we have breakers in our homes to prevent that from happening inside a wall. I hope..!

@kipman725 If the cap has been discharged, a simple shorting wire will do the trick even. Leaving them open is very dangerous.

I'm not sure what to think about that video. I have seen it before, but he almost seems to "fanboy" over those amps and I'm not convinced if what he is saying is genuine. At times he almost sounds like a salesperson. Minor detail, but he uses the term slew rate incorrectly. Slew rate is not the time it takes for the caps to charge back up.

Either way I'd of course be very interested to test the CVR amps. Looks don't tell the whole story. The Sanway also looks very well made internally, as do the Sinbosen amps, but they lack protection. Of course you won't care much about that in your HT but if your system goes silent on a gig you're in for trouble and I'd surely not want to risk that.
I know Sanway have changed their PSU and it might be better now. They added a fan where my blown transitors sat.

There are very few reviews or even general info about CVR.

A high displacement 15" driver will do very well even at loud levels down to like 20Hz. Since most movies nowadays don't have much content below that point, a single sub like this will do the job very well. When you start with BEQ and you're aiming for a good seat-to-seat variance it starts getting ridiculous, which is why you often see guys at AVS with 4 18" drivers in huge cabs or well.. more than that.

I think that my 2x21" rig is overkill for my use, but better have too much headroom than not enough..! Adding a BOSS riser to the setup (really just a sheet of plywood with two 12" drivers mounted to it, was 30 minutes of work) was the icing on the cake, since I get no low tactile response in my room (all stone and cement).
If you're into "feeling the bass" you might want to look into that. And as I said, since it's basically just a sheet of plywood with two holes in it, it wouldn't steal much of your time. And since you're looking to get a miniDsp already, the total cost for that might be around 150 bucks. It's far less gimmick-y than it seems.

It will be safe to work with from a humanoid standpoint after two minutes, but that still might damage electronics when working on the amp. I'd leave it disconnected for at least 10 minutes before working on it again or using a ~400R bleed resistor to shorten the PSU, which would result in a 1A current flow at 400V, which might be useful to be connected with a switch if you plan on working on the amp a lot. I think I have a 50W 32R resistor somewhere, which would already quicken the process from 50V down to zero. But oh boy if I leave it connected and then switch the amp on...

Heres a fun vid about capacitors. He has a shorting wire for storage on that thing or it would probably kill you if you touched it. This thing does over 80000A at 4000V.