WillistonAudioLabs Posted November 17, 2011 Author Report Share Posted November 17, 2011 i misstated my question. i meant rms not peak. are the rms values based on the gain at 100% on an unclipped signal? if so how do you acheive the unclipped signal? i ask this because i had an amp rebuilt and it came back with a rebirth cert. the wattage surprised me. upon inspection i noticed the gains where full tilt. i thought to myself there is no real work application where i will ever acheive a full gain unclipped. or so i feel. please correct me if i am wrong. an sorry to thread jack. PM me if you wish and admins can delete my last few posts if desired. as i know you are more knowledgable then i in this department and am in way questioning you but that of the method of testing that is used. thank you, NEUMAN I see where you are coming from and since I've mentioned max continuous RMS wattage, I don't think this is off topic. 1) Yes, my tests are based on a 100% unclipped signal - I've verified on my test receiver where it begins to clip (using o'scope), have this number marked w/ tape, so I know the signal is clean below this number. I've also verified voltage output on my Yamaha Receiver to be 3.5v before clipping. Not that it really matters, but should help understand the relationship between the receiver's signal and the gains on the amp. 2) When you mentioned your gains were "full tilt" when you got it back, this does not matter in testing. The amp is only going to put out a given amount of power, not any more just b/c the gains are maxed out. However, it will distort/clip sooner if the gains are turned up too high and you are feeding it a clean signal at 3-4V from your head unit. For example, if you amp's gains are maxed, your head unit may only make it to 10 out of 30 before the amp begins clipping. Using a device such as an o'scope or SMD's own DD-1 is important when matching a head unit and amplifier and for my testing, I match my source unit (Yamaha receiver) and each amp I test before obtaining the RMS power output. In matching the units, you would first determine when the source (head unit) clips, then back it up just slightly (most HU's today give you a number, so if it clips at 36, dial back to 35). Then you use the test signal to detect clipping at the amp, adjust the gains up until you see clipping, then back it just a little (w/ DD-1, wait until the light goes off. Using o'scope take the gains up until you see flattening of the waveforms, then back up until they are clean "waves"). 3) Some devices, such as my iPod Nano (1st gen) will go all the way to max volume w/o clipping. I found it easier to get precise adjustments by using a home theater receiver with a BIG, analog volume knob. My receiver is a Yamaha RX-V670 and I'll probably do another update video showing my test methods as they have changed a little since the video I made a few months ago. I hope this helps, if you have any other questions about this, PM me or email me at my username at gmail.com. See my videos on YouTube http://www.willistonaudio.com Many tests and demos of OLD and NEW SCHOOL car audio gear! See cool pics on Instagram @oldschoolstereo Link to comment Share on other sites More sharing options...
neuspeedescort Posted November 17, 2011 Report Share Posted November 17, 2011 i follow you. i use an o-scope on every car that leaves my garage. it awesome. wish i had one for all the years i have been doing stereo work. the main reason i asked is because both the amps i had repaired where old school fosgates by landis tech. so i wondered what he used as a bench. may be similar to yours. one was a punch 250a2. when doing the math on the scopes voltage as an estimated power rms it turned up about 45 watts short of the rebirth cert i had for it. now if i cranked it to max gain it achieved the rebirths numbers. the other was a the punch 75. it came back the same way but i never hooked it up. got in a crunch and sold it on ebay about 2 months ago. fetched almost 130 bucks. which brings me to another historic question. what did those go for new back in the day? that was about 5 years before i got into stereo's. thanks again for the history lessons, NEUMAN Link to comment Share on other sites More sharing options...
emperorjj1 Posted November 17, 2011 Report Share Posted November 17, 2011 working at an amp repair shop for some time just know that how the settings are when they leave may really not reflect anything at all. depending on the duration of the test how busy i was and several factors i would often play with the settings just to verify everything works as it should, sometimes before the full bench so it would leave with moderate usable settings and sometimes after so it would leave with all up all down or anything in the middle. we also had a nice signal generator that could give the amp as little or much signal as needed so couldnt really just slam an amp from bench to car without re-adjusting J. JMy CardomainFINISHED COBALT SS/SC DUAL ALTERNATOR PICS theres no such thing as too expensive when it comes to upgrades like that, because imo if you are gonna spend to upgrade then do it correctly rather then be a cheap ass ricer Link to comment Share on other sites More sharing options...
Primemova Posted November 19, 2011 Report Share Posted November 19, 2011 Neumann hi, hope you got out of your crunch I ended up with your punch X around about the same time, thanks. i follow you. i use an o-scope on every car that leaves my garage. it awesome. wish i had one for all the years i have been doing stereo work. the main reason i asked is because both the amps i had repaired where old school fosgates by landis tech. so i wondered what he used as a bench. may be similar to yours. one was a punch 250a2. when doing the math on the scopes voltage as an estimated power rms it turned up about 45 watts short of the rebirth cert i had for it. now if i cranked it to max gain it achieved the rebirths numbers. the other was a the punch 75. it came back the same way but i never hooked it up. got in a crunch and sold it on ebay about 2 months ago. fetched almost 130 bucks. which brings me to another historic question. what did those go for new back in the day? that was about 5 years before i got into stereo's. thanks again for the history lessons, NEUMAN Link to comment Share on other sites More sharing options...
cc_audio Posted November 19, 2011 Report Share Posted November 19, 2011 My wife's new.... er...oldschool system Do you have vids of this? If you don't you should get out there and take vids asap, so awesome! It's all gone! The Celica Build Feedback If I buy something from you, DO NOT USE FEDEX! Link to comment Share on other sites More sharing options...
Primemova Posted November 19, 2011 Report Share Posted November 19, 2011 Shawnk did this build for his partner, can't wait to see what he installs in his own ride. Link to comment Share on other sites More sharing options...
neuspeedescort Posted November 19, 2011 Report Share Posted November 19, 2011 Neumann hi, hope you got out of your crunch I ended up with your punch X around about the same time, thanks. i follow you. i use an o-scope on every car that leaves my garage. it awesome. wish i had one for all the years i have been doing stereo work. the main reason i asked is because both the amps i had repaired where old school fosgates by landis tech. so i wondered what he used as a bench. may be similar to yours. one was a punch 250a2. when doing the math on the scopes voltage as an estimated power rms it turned up about 45 watts short of the rebirth cert i had for it. now if i cranked it to max gain it achieved the rebirths numbers. the other was a the punch 75. it came back the same way but i never hooked it up. got in a crunch and sold it on ebay about 2 months ago. fetched almost 130 bucks. which brings me to another historic question. what did those go for new back in the day? that was about 5 years before i got into stereo's. thanks again for the history lessons, NEUMAN glad it went to a good home. i know i sold almost all my old school stuff. none of it was the same models so it was hard to find a build to use it for. don't know if you remember my other sales but i had a "the punch rocker series" 12 in working condition that i sold also. other then some silicone on the basket from a previous owner it was mint and in working condition. NEUMAN Link to comment Share on other sites More sharing options...
Primemova Posted November 19, 2011 Report Share Posted November 19, 2011 Yea liked your gear sorry to hear it was a forced sale. Your sub was a SP-412 from memory my setup would've put way too much power into it.IMO the series 1 punch75 would've been a good match. I was keen to buy your P75 but had no use for it but I would be interested in the landis figures on the rebirth, do you remember them? or have pics? Maybe put your fleabay pics on this thread for everyone to view. Link to comment Share on other sites More sharing options...
neuspeedescort Posted November 20, 2011 Report Share Posted November 20, 2011 48.30 watts rms @ 4ohms stereo per channel. just a little more then the rated 37.5. i figured it would have ran the 12 very nicely. but i couldn't really find a good use for it. i got it off craigslist for 20 bucks originally about 2 years ago. one channel was static and the other was clear. opened it up and the caps where leaking. so i sent it to landis. i sent a 250a2 and the same time. it re-birthed at something like 97 watts rms. the thing that i do know about landis tech is all his tests are done at 12.5 volts. so you know the power should really be much more when in an actual real car application. i need to upload the handful of photos i have to photobucket but i will get around to soon seems there is a demand. lol NEUMAN Link to comment Share on other sites More sharing options...
Nine8SST Posted November 20, 2011 Report Share Posted November 20, 2011 My wife's new.... er...oldschool system This is a thing of beauty and really belongs in SOTM.....especially this month!!! Please, tell me if you have a build log so we can get you nominated if you do. Amazing!! 1998 SS/T Ram Build Log - Kenwood KVT-514 and KNA-G510 Navigation - 2 DC Level 3 12" - Components??? - Sundown ??? - Sundown??? - Knu Konceptz - Second Skin Dampy Pro - XS D6500 Link to comment Share on other sites More sharing options...
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