Premier PRS-X720 amplifier - Page 1
Forum section: electronics / repair

author: zz28zz
author_rank: Regular Contributor
timestamp: April 07, 2019, 06:19:52 am
content: This is a high-end 2-channel car stereo amplifier made by Pioneer. Bought a couple of them ~15 years ago used. Great amplifiers but now one of them has a scratchy sound coming from right channel that gets worse as volume is increased.Opened it up and went straight for the electrolyte caps due to it's age. Of the 7 large caps, 3 are tall and thinner and 4 are short and fat. Advertised capacitance is 4700uF for all 7. The 4 short fat caps all had a dome shape on top but the other 3 were flat on top. Removed and tested all 7. The tall thinner ones measured 4976uF, 5050uF and 5310uF. The 4 short fat caps measured 1201uF, 3140uF, 3252uF and 3234uF. Assuming a 20% tolerance, all of the short fat caps are out of limits.Questions:1. Where can I download a schematic for this amp?2. What's the purpose for the rtv looking substance gluing the caps together and to the board? Does it need to be re-applied? See enclosed pic.3. Do the symptoms described sound like a bad cap? (I'll be replacing all 7 anyway)I've repaired thru hole PCBs before but always had a schematic. Never tackled an audio amplifier before. Any advice is much appreciated.Thx!

author: coromonadalix
author_rank: Super Contributor
timestamp: April 07, 2019, 11:19:36 am
content: serv manualyou have to register, its free, just did1)https://www.hifiengine.com/manual_library/pioneer/prs-x720.shtmlchoose the CRT2361 2.9 megs, the other is incomplete.2) in some case the glue is for mechanical purposes, you do know in a car there is lots of vibrations ...3) i would check if you have some dc voltage going out on the speaker terminals at zero volume, check the supply lines if they are equals, and the ripple if yo have a scope.Before jumping to the caps, did you powered it up and tested the sound ?

author: mzacharias
author_rank: Frequent Contributor
timestamp: April 07, 2019, 01:26:17 pm
content: The big power supply caps are not going to cause your symptom on only that one channel. Perhaps they should be replaced, that is another matter though.

author: Twoflower
author_rank: Frequent Contributor
timestamp: April 07, 2019, 01:39:44 pm
content: Not sure but the temp-rating on the bigger diameter caps looks like 85°C (you can only see the 5°C on another M85) which is for a car amplifier quiet low rated...If you're replace them, go for 105°C types unless you're living in very cold regions. Of course for the others as well. They should probably low ESR types, which usually are 105°C types anyway.

author: zz28zz
author_rank: Regular Contributor
timestamp: April 08, 2019, 02:58:35 am
content: Downloaded the manual. Thx for the link!Should have known the glue was for mechanical reasons. I'm used to working on lab equip where there's no real vibrations.I re-installed the caps I pulled out for testing. Powered up amp on the bench with signal generator and scope connected to speaker terminal. Made a makeshift dummy load from a car taillight bulb (~3 ohms static). I've been running freq sweeps from 500hz to 5khz and watching scope. Everything looks good as best I can tell. Not sure what to try next short of re-assembling and re-installing it in the boat (PITA).Due to the physical size/pin spacing, finding replacement caps hasn't been so easy. Cannot find anything but 85 deg rated caps in the size I need.

author: zz28zz
author_rank: Regular Contributor
timestamp: April 08, 2019, 08:53:10 am
content: I got some 8-ohm home speakers and a head unit (home stereo CD player) connected while on the bench. Sure enough, right channel sounds distorted when playing music, even at a low volume level. Swapped speakers and input connections. Right channel of amp still sounds distorted.Rail voltages on signal side and power side steady and equal (but opposite). +/-15V supply looks good.I did run across something odd when scope was connected to signal output FET gates. With a 2-channel signal generator outputting a 1khZ sine wave to both channels (at the same drive level), the Pos FET gates on the right side have a P-T-P value of 2.36V while the left side is 1.32V. See attached. Swapped cables at signal gen but it didn't change anything.When connected to signal output Neg FET gates, the right side doesn't have the same offset as the left side. See attached.Blue trace is the bad (right) side in both pics.Only change between screenshots was moving scope probes (didn't touch signal gen or any other adjustments).Swapped cables at signal gen again but it still didn't change anything. Changing freq on the signal gen didn't have any effect in regards to the different P-T-P value issue or the offset issue.Hoping someone can make some sense of this.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 08, 2019, 10:30:24 am
content: normally for debugging an amp, car amp, shoot a 1khz signal at 0db, and follow its path thru the amp on each channel until you see a discrepancy between the chanels, and work your way.Did you check for dc voltage at the speakers terminals ??

author: zz28zz
author_rank: Regular Contributor
timestamp: April 08, 2019, 04:42:08 pm
content: My cheepo sine wave generator doesn't display output in db. Just shows output voltage and offset which was 0.02V and zero for offset.. Maybe I'm missing something here??Forgot to measure the voltage at speaker terminals. I'll check that tonight. If I do find voltage at speaker terminals with amp idling, is that a sign of leaky signal output FETs?

author: coromonadalix
author_rank: Super Contributor
timestamp: April 08, 2019, 08:33:08 pm
content: not necessarely, you may have an imbalance on the output stage, the output stage is a push pull typeEx: you may have a transistor / mosfet who drive / leak a little to a supply line, in the end you end up with a dc voltage on the output speaker and you may fry a speaker if a protection doesnt kick, or if its not equiped with this circuit.The speaker terminal is a cross over between the positive and negative supply, it should read zero, or pretty near zero in the millivolts range. Only the ac signal IE: audio is amplified

author: zz28zz
author_rank: Regular Contributor
timestamp: April 08, 2019, 09:31:53 pm
content: Understood, thx! I'll update later this evening when I get a chance.

author: zz28zz
author_rank: Regular Contributor
timestamp: April 09, 2019, 01:28:33 am
content: Made voltage measurements on the speaker terminals with input cables and speakers disconnected. Good channel= -17mV. Bad channel= +50mV. Is that a significant amount?

author: zz28zz
author_rank: Regular Contributor
timestamp: April 09, 2019, 06:05:14 am
content: Found something interesting this evening while playing with the scope and signal gen.I connected one scope probe to the gate and one to the output (source) of the "bad channel" negative MOSFETs.At 80hZ the output follows the gate signal nicely, however as freq is increased, the gate signal continues to look fine but the output signal starts looking less and less like a sine wave. The top half of the sine wave looks pretty good but the bottom half is not so good. At 200hz, it looks really bad. I saved the data starting at 100hZ and stepping up in 100hZ increments up to 1khZ. See attachments. Blue traces are the gate signals. Disregard the measurement data at bottom of pics. Still trying to figure out how to make that read right.Above 1 khZ the neg MOSFETs output quality continues to improve.Negative rail voltage stayed within ~150mV of set-point (41.5V) the whole time.Repeated same tests on good channel and the outputs followed the gate signals perfectly from 80hz to over 20khZ.I then moved to the bad channel positive MOSFETs. They behaved ok at lower freqs but had a similar issue at high freqs.Time for a new set of audio section MOSFETs??

author: coromonadalix
author_rank: Super Contributor
timestamp: April 09, 2019, 08:19:35 am
content: i would say the negative side of the signal is distorted, that relate to the negative voltage side of the amplifier

author: zz28zz
author_rank: Regular Contributor
timestamp: April 09, 2019, 06:03:38 pm
content: So, bad MOSFETs on neg side? I don't see much else it could be except maybe the voltage and current protection circuits running amuck.

author: zz28zz
author_rank: Regular Contributor
timestamp: April 10, 2019, 07:34:53 am
content: Found one of the bad channel neg-side FETs has a significantly lower mean gate voltage than the other two partner FETs while injecting a 200hZ sine wave.Got all the audio FETs and 7 caps on the way. It will be interesting to see what the old FETs look like on the curve tracer after ~20 yrs of operation.

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 13, 2019, 02:50:36 pm
content: I'd actually be really surprised if one of the power FET's was the trouble.Assuming that bad solders on the copper side and the +/-50V supplies (TP927/TP928) have also been checked, and given that symptoms seem frequency dependent things I'd be looking at first are:C501, C551, C555. (Or equivalents on the concerned channel if I have the wrong one...

author: zz28zz
author_rank: Regular Contributor
timestamp: April 13, 2019, 08:26:38 pm
content: Well, things went from promising to down right ugly.While awaiting delivery of the new audio output FETs, I installed the 4 new large rectifier caps and the 3 new caps on the primary side of the transformer. Then I figured that since there are 3 audio FETs in parallel (for each polarity of each channel), I could test audio output at a low level with one removed. I removed the suspect audio output FET from the circuit and powered up amp. Sine wave signals looked good at all freqs on both channels. Connected CD player and music sounds good. I felt I had this one in the bag.New audio output FETs arrived yesterday and I installed them last night. I was fully prepared for the sweet sound of music but instead I got a small fire immediately after applying power.2 of the power section FETs blew off their source legs off. I pulled all 6 of the power FETs off and cleaned up the soot. Tested all 6 of the FETs with hand-held meter and every one has a dead short between gate and drain. With the FETs removed and amp powered up, checked the gate signals. I see a nice clean square wave with 11.2V P-T-P amplitude and a freq of ~34khZ at all 6 positions. See attachment. I'm stumped as to why this happened. ESD??Checked Digikey and found the original power section FETs are obsolete. Found an option that looks promising. Here's links to both. Does this look like a good match?https://www.digikey.com/products/en?keywords=P50NEhttps://www.digikey.com/products/en/discrete-semiconductor-products/transistors-fets-mosfets-single/278?k=&pkeyword=&sv=0&pv606=1&pv570=73&umin2068=80&umax2068=300&rfu2068=V&pv608=1970&pv1993=4&pv1236=26&pv2262=u110nC+%40+10V&sf=1&FV=ffe00116&quantity=&ColumnSort=0&page=1&pageSize=25

author: Twoflower
author_rank: Frequent Contributor
timestamp: April 13, 2019, 09:08:26 pm
content: Not sure, but could that be that this was caused by a short over the heat-sink? Have you forgot to insulate the FETs from the heat-sink? Usually they need to be electrically-insulated.

author: zz28zz
author_rank: Regular Contributor
timestamp: April 13, 2019, 09:31:32 pm
content: All backs of all the TO-220 FETs are sandwiched up against some unknown material abt 1/4" thick that's non-conductive. That material is heat sunk into the shell of the amp. Never touched the power side FETs. Also verified the heat sink compound isn't conductive.

author: zz28zz
author_rank: Regular Contributor
timestamp: April 13, 2019, 11:04:54 pm
content: Started checking audio side of amp and discovered the +45V and -45V rails were shorted together. Started loosening the clamps for the audio MOSFETs and the short went away. Cleaned up the "unknown" material where the FETs source heat to. It appears to be alum with a non-conductive coating. After cleaning it up, found a few small places where I nicked the coating and created a path for current (reminder to self: don't use a knife to clean the heatsinks). Since both polarities of FETs are on the same chunk of alum, it shorted out but not until the very last tightening of the clamps. Looks like I will need some sort of insulating film between the FETs and the heatsink. Good call Twoflower. Thanks.

author: David_AVD
author_rank: Super Contributor
timestamp: April 13, 2019, 11:34:22 pm
content: Did the original FETs have mica (very thin clear) insulators under them?

author: zz28zz
author_rank: Regular Contributor
timestamp: April 14, 2019, 01:31:40 am
content: No insulators. Just the coating on the heat-sink.A couple of the "nicks" turned out to be gouges. You could run your fingernail over it and feel the metal sticking up just a tiny bit. They just happen to line up with the back-side of a neg FET and pos FET. Rotten luck there. I dressed up the damage with some crocus cloth wrapped around a tiny file so that I had a slight depression then used a toothpick dipped in enamel paint to fill the depressions. Next step is to re-assemble and test for shorts.Still need to find replacement power FETs and get them on order. May need to start another thread for that.

author: Twoflower
author_rank: Frequent Contributor
timestamp: April 14, 2019, 09:49:31 am
content: You should go for insulation sheets. Rely on the already damaged Aluminium-oxide or coating isn't the thing I would go for. Also how even is the surface now with the applied paint and how good is the thermal performance of the used paint?Look for a 0.5 or 1mm silicone sheets to mount the FETs. You can get some 10x10cm sheets instead of individual TO220 sized ones. Double check the datasheet for the pads if they're electrically insulating. If you use mica sheets don't forget the thermal grease.But as you wrote you measured on the fried FETs a short to the gate. That might have created some other problems at the gate-driver.

author: zz28zz
author_rank: Regular Contributor
timestamp: April 14, 2019, 06:32:33 pm
content: I don't have a way to accurately measure the flatness of the heatsink at the painted spots but they look flat using the naked eye. I'd estimate the painted spot makes up less than 10% of the surface area of the FET. Also have no idea of the thermal conductivity of the paint. I assumed the heat sink compound would help transfer the heat around the painted areas.The silicon pads would be a good insurance policy. I was concerned about adding any additional layers between the FET and the alum. If I use insulating sheets, there would be two layers, the oxide layer and the silicon sheets. Maybe I'm over thinking this. I could grind off the oxide coating but it wouldn't be nearly as flat as it is now.Ive seen where folks mention the mica sheets tend to crack over time so the silicon sounds better in that regard. Is the thermal grease the same as heat sink compound? Is heatsink compound needed when using silicon sheets or is it used dry?The gate signals look OK with no FETs to drive. Hoping they remain so when FETs are installed.

author: Twoflower
author_rank: Frequent Contributor
timestamp: April 14, 2019, 06:49:54 pm
content: Thermal grease or thermal compound is not needed for the silicon sheets. Only fuse the grease for mica or no insulation material. For the silicon pads, I would use "single side sticky" ones. that way you can remove it when needed.If you don't get the surface as smooth as it is supposed to be you're make it probably worse. So no grinding.I've nearly killed my scope because the TO-3 mica-sheet in my lab-power supply got defective over time. That caused a nice DC short-circuit over PE.

author: zz28zz
author_rank: Regular Contributor
timestamp: April 14, 2019, 07:22:17 pm
content: Thx for the education.Here's what I came up with:https://www.digikey.com/product-detail/en/t-global-technology/H48-6-150-150-0.5-1A/1168-1213-ND/3042042Thermal conductivity is 3.2W/m-K . I have no idea if that's good or not but it's on the high end of the reasonably priced silicone sheets.It's a 0.5mm thickness sheet. From what I've found online, 90V can only jump ~.0005" in free air.0.5mm = .019" so I believe 0.5mm is plenty thick enough for electrical isolation.Just tried to order but Digikey reports they are temporarily not taking orders??

author: zz28zz
author_rank: Regular Contributor
timestamp: April 15, 2019, 01:03:51 am
content: Digikey is up again. Parts on the way.

author: zz28zz
author_rank: Regular Contributor
timestamp: April 19, 2019, 01:39:59 am
content: Got the power FETs and silicon sheets installed. Couldn't find a 1 amp fuse to install but did have a 3 amp. It blew when power was connected just charging up the primary side caps. Installed one of the three 30A fuses and powered-up. No issues at all. Installed the other 2 fuses. Amp sounds better than ever. Adjusted idle current on both channels and played it fairly hard for 30 mins. Probed around with my temp probe. Nothing got over 100 degs F. Couldn't be happier. Thx for all the help.One final question: I still need to apply the glue that I originally found gluing the large caps together and to the board.I have some marine sealant (3M 4200) that grips pretty well and is non-conductive. Can I use that or is the glue something special?Amp is going back in the boat so it needs all the help I can give it in regards to shock protection.

author: David_AVD
author_rank: Super Contributor
timestamp: April 19, 2019, 11:58:07 am
content: Make sure that the silicone is neutral cure (non acetic). Super common over here, some have heard that it's not as easy to find in the US?

author: zz28zz
author_rank: Regular Contributor
timestamp: April 19, 2019, 06:13:02 pm
content: Thx for the heads-up on the non-acetic silicone. After digging around on the net, I've found the safest/easiest/quickest product to acquire is GE Silicon II. Heading up to the hardware store today anyway so I'll pick some up there.I would hate to mess things up at this point of the repair.

author: zz28zz
author_rank: Regular Contributor
timestamp: July 07, 2019, 10:08:16 pm
content: Well, things went well for ~3monnths. Last Thurs the amp blew out most of it's magic smoke. Got it on the bench and found all 6 fets in the power section were toast. Pulled the board out and started poking around. Just like last time, I find the +45V and -45V rails are shorted together.Last time it was from the back of the audio fets shorted to the heat sink effectively connecting the two rails. Now, with the heat-sinks not attached to the fets, I still measure 0.4 ohms between the + and - rails, but neither rails is connected to ground. Looked at schematic and the only place I can see where the two rails could possibly connect (w/o connecting to ground) is thru the rectifier diodes. I removed the diodes (that bench test OK) but still have a short across the rails. Visually inspected board looking for solder blobs & etc, but can't find anything wrong. Any ideas on how to isolate the short?

author: zz28zz
author_rank: Regular Contributor
timestamp: July 09, 2019, 05:00:00 am
content: Pulled all 6 FETs from one channel and short disappeared. Tested the FETs I had pulled and sure enough, 1 shorted (Drain/Source) FET on the pos side and another on the neg side. They look fine visually. No evidence of heat damage or arcing at all. All the failed parts are IR brand and received from Digikey. Amp wasn't being pushed hard at all. Got another set of FETs coming but still scratching my head as to what could have caused this.

author: zz28zz
author_rank: Regular Contributor
timestamp: July 14, 2019, 07:28:18 pm
content: After visual insp found 1 resistor (R669) in the I-V prot circuit that had burned the board and was cracked but measured OK. It was a carbon 1/8W 2.2k. Replaced with M/F 1/4W of same resistance. Also found 2 resistors in parallel (R566 and R550) that had burned board. They were carbon 24K 1/8W. Didn't have any 24K's avail so installed one 22K and a 27K. Both 1/4W carbons. Measured with the 2 in parallel and got 12.04K ohms, so I think I'm OK there now.Power section FETs replaced and primary side of power section is good. Re-installed rectifier diodes. Connected scope to +/- 45V rails and applied power to amp. +/- 45V rails both went to abt 20V then started dropping back towards zero within abt 1/2 a second. Removed all the remaining audio section FETs and the +- 45V rails are OK now. Installed 1 new FET for + side and 1 new FET for - side. Did the same for the other audio channel.Powered up and both rails shorted together thru the audio FETs again. Bench test shows 1 + FET and 1 - FET shorted (source/drain).With all audio FETs removed, applied 1K sine-wave signal to both channels and connected scope to audio FET gate pins (no FETs installed, just a test point pins). I got a signal at the gate pins but it looked more like a square wave. Not sure if that's right or not. Doesn't sound right. After a couple of mins, the signal at the gates disappeared. I brushed my arm against the -15V supply BJT and noticed it was hot. Measured -15 and it's at ~-1V now. Pulled the output leg (emitter) of the BJT (Q908) that supplies -15V and BJT output still measured ~-1V. Checked zener (D909) that controls base voltage/current and it was shorted (to ground).Attached is a pic of the schematic with the over heated (and replaced) components circled.Next 2 posts are expanded views of same areas of schematic..Questions:1. Any issues with first paragraph?2. Paragraph 3, should sine wave injected at input of amp look like a square wave (like it was clipping) with input gain turned way down and input from sine wave gen at 0.45V? (amp should handle up to 6.5V on input.)3. At first I thought one of the audio amps was shorting the -15V, then found the zener D909 shorted. Any thoughts as to why the zener shorted?4. Any thoughts why R669 over-heated? (I checked Q655 and Q661 for shorts)5. Any thoughts why R566 and R550 over heated?Thx!

author: zz28zz
author_rank: Regular Contributor
timestamp: July 14, 2019, 07:29:33 pm
content: I-V prot circuit.

author: zz28zz
author_rank: Regular Contributor
timestamp: July 14, 2019, 07:30:10 pm
content: Right channel.

author: zz28zz
author_rank: Regular Contributor
timestamp: September 02, 2019, 11:27:10 pm
content: Back at it again this weekend. Grabbed another amp which is the baby brother of the broken amp. Circuits are almost identical, just fewer FETS and 45v rails are 37V rails on the little one.Replaced 15V zener on the base leg of the BJT that makes up the -15V regulator. Did the same for the +15V BJT. Now have 14.7V and -14.7V so that's appears to be OK now. Noticed the 15V BJTs get hot after abt 1 min or so but they are not heat sunk with the board on the bench. I'm forced to power on, take measurements and power off to keep them from getting too hot. Amp seems happy with all the audio FETS removed and nothing is getting hot.Installed one of the 3 audio output FETs at each location, R-channel+, R-channel-, L-channel + and L-channel-. Connected scope to monitor +45 and -45V rails and applied power. Rails went to abt 20V for abt 1 second, then started dropping again. 30A fuse blew. All 4 audio FETs shorted again. This is with the amps RCA audio inputs shorted with a 1k ohm resistor (used to set idle current) and gain set to almost nothing.Measured gate signals to the audio output FETs. With no input signal, both the + and - FETs are close to the positive rail voltage. After abt 15 seconds, they both drop to close to - rail voltage. Both channels are doing the same thing except one channel takes a few more seconds before gate voltage dives towards other rail. On the good smaller amp, the audio output FETs gate voltage is abt 3-4V and steady.Defiantly appears the gate voltage to waay to high for the audio output FETs and that's turning them on hard causing them to short out.Looking at the schematic, I see a couple of suspects for each channel, but can't find anything that would cause both channels to do this. I've measured the outputs of every op-amp and measured the voltages at base, collector and emitter of every BJT in the audio path. Compared to good amp and all matches until I get to the portion where +50V and -50V are introduced. At this point both channels are isolated (I believe) so both channels would have to have the same failure mode, which seems unlikely.I've also monitored the +/-50V rails, the +/- 45V rails and the +/-15V rails. They are all where they should be and stable when the audio FET gate voltages dive from ~+40 to ~-40V.Attached are the scope traces when connected at either the right channel audio output FET gates or left channel audio output FET gates and power is applied. Note the time scale is larger for the Left channel since things happen a little slower on that channel.Does anybody have an idea what's causing this? I'm stumped.

author: zz28zz
author_rank: Regular Contributor
timestamp: September 02, 2019, 11:28:50 pm
content: Left channel at power up.

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 30, 2019, 08:18:52 am
content: I'll also be referring to that other post at times.The output FET's are source followers, so having +/-40V on the gates is not a problem as long as the source is able to follow, this is what happens all the time when you play music at full power.What you do want to worry about is the differential voltage between gates as too much differential means both sides are conducting too much, current, heat... destruction.Where you do have a problem though is if your gate voltages settle at the shown voltages when idle, this means a lot of DC on the outputs and you shouldn't connect a load until you have solved this.You have double checked FET drains are insulated from the heatsink?I'm not sure adding a 1k resistor to the sources is the best way to troubleshoot. I'd go for an adequate lab supply if you have one that can output +/-45V or inserting a 12V 20W bulb on each rail before the output transistor drains. (Edit: this may be a little optimistic, maybe higher voltage & power bulbs is safer.)Turn the idle current trimpots right down towards R505, R506, if layout is as on schematic.I'd be checking on: Q555, Q557, Q559, Q573, D551, (open D501), R501, R563, R567, R569, trimpot (never ever neglect the trimpot in the bias circuit...), gate resistors.

author: zz28zz
author_rank: Regular Contributor
timestamp: October 15, 2019, 05:36:10 am
content: Quote from: shakalnokturn on September 30, 2019, 08:18:52 amLast week while troubleshooting a decided to try bypassing the 1K ohm resistors I had placed on FET source legs and turn amp on just long enough for scope to trigger and see if I get any signal at base of right side transistor of Q552. (I believe this is the what's supposed to keep the output FET gate signals from getting too powerful). Got away with it twice, but the third time I fried the FETs again. So gotta order more parts,, again.When I look at base of Q574, I see the 1khZ signal I injected going 95V PTP even with input signal barely on (~70mV PTP) and gain turned waay down. When I check the other amp I have, voltage stays much lower even with a higher voltage input signal (200mV PTP).With both channels doing the same thing, it makes me think there may be something wrong with V/I protection circuits. I did have a burnt resistor at R669 that I replaced already.There's also another circuit made up of Q203, Q204 and Q 205. Appears it's capable of sending the input signal to ground on both channels but not sure why you would want to do that. Emergency idle-down signal from IC651??

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 15, 2019, 05:50:34 am
content: Q203-4-5, muting.

author: zz28zz
author_rank: Regular Contributor
timestamp: October 16, 2019, 04:30:25 am
content: Makes sense, but there's no muting button. Maybe it automatically activates at start-up to save speakers??