Guest Posted December 14, 2015 Posted December 14, 2015 @@125dBmonster...... That is some scary reading. Glad to say, defiantly not me..... Must tell Mrs SETsergio... ;-) Yea, me either, kids, dogs, Wife and general dis array most of the time. Would have been sent to the funny farm years ago. Although, there is a space where the stereo's sing, no one is allowed to touch, put down a cup or leave anything behind, the man cave is my domain, my sanity relies on it.
Guest Posted December 14, 2015 Posted December 14, 2015 (edited) Those with OCD unite, please stand in a straight line, shortest to tallest, in alphabetic order and all face forward. Scary stuff, that must be a symptom, @@mwhouston, how many times a day do you wash your hands ? Edited December 14, 2015 by Guest
mwhouston Posted December 14, 2015 Author Posted December 14, 2015 Scary stuff, that must be a symptom, @@mwhouston, how many times a day do you wash your hands ? Put it this way. There is no way I could be in a job where I get my hands dirty. Fortunately with 45 years in technology it has never been a concern.
mwhouston Posted December 17, 2015 Author Posted December 17, 2015 (edited) Unleash the beast; my 250W IRS Class D amp is brighter sounding by far than the Tripath amp. The Tripath amp is very analogue sounding and I would never say overly bright but definitely detailed. To get a good balance between bass and treble I had to pad the tweeters down by 9db with the IRS Class D amp. A flat balance is 7db down so we are only talking 2 more db. Now I have a 250W Class D amp with a 760W PS capable of delivery 16A continuously with storage caps capable of delivering 700A instantaneously (M-Lytic) driving 98db efficient 12" speakers. Volume was controlled by my tube preamp. I decided 60s, 70s and 80s Rock on vinyl was the way to go and loud. Dynamic head room was off the planet and there was drive in the music which was intoxicating. Still a little deaf days later. http://retro-thermionic.blogspot.com.au/2015/03/250w-ir-class-d-amplifier.html Edited December 17, 2015 by mwhouston 1
Newman Posted December 17, 2015 Posted December 17, 2015 Unleash the beast; my 250W IRS Class D amp is brighter sounding by far than the Tripath amp. The Tripath amp is very analogue sounding and I would never say overly bright but definitely detailed. To get a good balance between bass and treble I had to pad the tweeters down Hi Mark. With Class D amps, the output filter is tuned to give flat treble FR with 8 ohm loads. With low-impedance loads, the treble response tails off. With high impedance loads, the treble response rises. IMHO that is why your IRS sounds sharp with your VoXConcentriC. The tripath might sound different because it might have a different degree of sensitivity to load variations.
mwhouston Posted December 18, 2015 Author Posted December 18, 2015 Hi Mark. With Class D amps, the output filter is tuned to give flat treble FR with 8 ohm loads. With low-impedance loads, the treble response tails off. With high impedance loads, the treble response rises. IMHO that is why your IRS sounds sharp with your VoXConcentriC. The tripath might sound different because it might have a different degree of sensitivity to load variations.With this particular Class D the power goes up as the frequency increases. At 50KHz the level is up 2db. After saying that at 20K it is only up 1db if that. It starts to rise about 5K.This one is sold by Digikey as a scalable Class D, the higher the B+ the more power out to 250W pc RMS @ 0.01% THD. With the right speakers or with your speakers balanced for treble and bass it is really magic. I was reading where one highend speaker company (forgotten the brand now) has a switch to reduce the tweeter energy. It gave a 1db reduction. I would have thought it not noticeable. I have made about 6 tweeter pads for my Beymas to work balanced with both 2.5W tube amps and 250W Class Ds. It is amazing the difference just a few db can make.
Newman Posted December 18, 2015 Posted December 18, 2015 Yes, I understand. I was talking about the way that the treble response of a class D amp changes when the speaker impedance changes. The plot below shows an IRS amp's treble is much brighter with an 8 ohm speaker attached than with a 4 ohm speaker. Your Beyma is 16 ohms in the treble, so imagine how bright the treble is from the IRS. I thought this might explain your observation. cheers 5
Hergest Posted December 18, 2015 Posted December 18, 2015 Yes, I understand. I was talking about the way that the treble response of a class D amp changes when the speaker impedance changes. The plot below shows an IRS amp's treble is much brighter with an 8 ohm speaker attached than with a 4 ohm speaker. iraudamp7d.pdf.jpg Your Beyma is 16 ohms in the treble, so imagine how bright the treble is from the IRS. I thought this might explain your observation. cheers Now that's interesting. Is that a general rule with all class D amps or a specific type? One thing I dislike greatly is a harsh treble response. 1
Newman Posted December 18, 2015 Posted December 18, 2015 (edited) It's a general rule but not universal, e.g. I heard comment that ncore are exempt. The actual degree of sensitivity to load impedance depends on the individual class D amp's output stage design. In time, as class D switching frequencies go up and up, this effect will disappear. Also, it's not about harshness: 4-ohm speakers would sound ever so slightly soft. And some speakers with really low treble impedance, e.g. some electrostatics and ribbons, could sound noticeably softer than normal. [edit: also also, the IRS seems to be tuned for 4 ohms, whereas others I know to be tuned for 8 ohms, and would not sound harsh with 8 ohm speakers. Haven't checked the Tripath.] Edited December 18, 2015 by Newman
mwhouston Posted December 18, 2015 Author Posted December 18, 2015 (edited) Yes, I understand. I was talking about the way that the treble response of a class D amp changes when the speaker impedance changes. The plot below shows an IRS amp's treble is much brighter with an 8 ohm speaker attached than with a 4 ohm speaker. iraudamp7d.pdf.jpg Your Beyma is 16 ohms in the treble, so imagine how bright the treble is from the IRS. I thought this might explain your observation. cheers Yes agree but a handful of resistors can help with the top end. The way it all sounds at the moment is pretty right. Lets face it all gear is a compromise and the Ds some thing really well. Edited December 18, 2015 by mwhouston 1
mwhouston Posted December 18, 2015 Author Posted December 18, 2015 Now that's interesting. Is that a general rule with all class D amps or a specific type? One thing I dislike greatly is a harsh treble response. The Tripath T4 amp I have does not follow this type of behaviour. It is very tube like and has a great warmth. Also the Sure 100W module is also another warm sounding module and even better you change the inputs caps to better caps. There is only one cap in the signal path in a Class D amp. With my IRS Class D I have upgraded the inputs caps.
mwhouston Posted December 18, 2015 Author Posted December 18, 2015 Newman, you got me thinking. If I could make the tweeter section of the Beymas look 8ohm to "Class D" then shrill may not follow me. I can't make the driver 8ohm because the the Xovers are designed around 16ohms. BUT I can make the tweeter Xover (indidivual Xovers for bass and tweeter) look 8ohms. From the Xover to the drive can still be 16ohm and all the pads I have made based on 16ohm will still work. The amp will see 8ohms. By putting a 16ohm resistor across the input to the tweeter Xover will make the tweeter look like it is a 8ohm component. Whatever 16ohm base pads I offer at the driver will not change the total impedance. "FLATTEN THE CURVE".
Newman Posted December 18, 2015 Posted December 18, 2015 Sure. For the IRS you could even make it an 8R resistor, since its output seems to be tuned for 4R. Fairly hefty resistor needed as it will see the full output voltage of the IRS feed to the speaker. 1
mwhouston Posted December 18, 2015 Author Posted December 18, 2015 Sure. For the IRS you could even make it an 8R resistor, since its output seems to be tuned for 4R. Fairly hefty resistor needed as it will see the full output voltage of the IRS feed to the speaker. The resistor would only need to go across the tweeter Xover. With high efficiency speakers there is not a lot of power required. I'm thinking a 10W wire wound. The tweeter is 105db efficient. Too lose 3db across the resistor is nothing.
Newman Posted December 18, 2015 Posted December 18, 2015 The resistor would only need to go across the tweeter Xover. And doesn't the tweeter crossover go across the full amp terminals? It sees the full-power, all-frequencies output of the amp, I would have thought. 1
mwhouston Posted December 18, 2015 Author Posted December 18, 2015 And doesn't the tweeter crossover go across the full amp terminals? It sees the full-power, all-frequencies output of the amp, I would have thought. I bi-wire but on reflection the 16ohm resistor or whatever befire the tweeter Xover will be reflected both to the amp and the bass Xover. Guess I'm back to padding down after the tweeter Xover. I have been listing to this combo for a while now on and off and it sounds balanced. I put in a couple of hard hours last night listening to classical natural trumpet and Forte piano. It all sounded really excellent and right balance. I may have it all solved. 1
mwhouston Posted December 20, 2015 Author Posted December 20, 2015 It appears I'm down to one Class D after an SNA members thought the T4 I have may work better with his speakers. Lucky I have one more Class D left and today raised the treble level very slightly. Balance with the Beymas is -7db pad on the tweeter. I had been using -9db but today felt the top end was a little suppressed. Back to flat, -7db. Better but once more a I require a few days to try lots of material. Did enjoy today though, duelling double basses. I have a 1500Wpc Class D to build. I have all the parts just need the time. 1
rowuk Posted January 24, 2016 Posted January 24, 2016 (edited) My experience is that efficient speakers give us far more amplifier choices - also very high quality, low powered amplifiers. It is also easier to build a high quality, multi amplified, high efficiency system as matching the amp to the drivers is far less costly. High efficiency speakers also can give us the uncompressed acoustic output where music needs it most: 80-300Hz. For those so inclined, BL horns or transmission lines need to be made carefully to avoid a FR suckout between 100-200 Hz due to cancelling effects. Mark, I have been watching your posts elsewhere. You certainly have made a lot of pretty cool stuff. Edited January 24, 2016 by rowuk 2
mwhouston Posted January 24, 2016 Author Posted January 24, 2016 (edited) My experience is that efficient speakers give us far more amplifier choices - also very high quality, low powered amplifiers. It is also easier to build a high quality, multi amplified, high efficiency system as matching the amp to the drivers is far less costly. High efficiency speakers also can give us the uncompressed acoustic output where music needs it most: 80-300Hz. For those so inclined, BL horns or transmission lines need to be made carefully to avoid a FR suckout between 100-200 Hz due to cancelling effects. Mark, I have been watching your posts elsewhere. You certainly have made a lot of pretty cool stuff. Thanks for the nice comment. I just finished another tube phono preamp, another Tripath T4 amp and currently having some boxes made for the new 15" Beymas I got before Xmas. There are other projects in the pipeline for example a metal tube 6L6 amp.Currently I'm enjoying the new 180W Tripath amp with the high efficiency 12" Beymas. http://retro-thermionic.blogspot.com.au Edited January 24, 2016 by mwhouston
Swarm Posted February 16, 2016 Posted February 16, 2016 have you looked at any YJ stuff ? aud prices http://www.yuan-jing.com/index.php?route=product/category&path=59 2
mwhouston Posted February 17, 2016 Author Posted February 17, 2016 have you looked at any YJ stuff ? aud prices http://www.yuan-jing.com/index.php?route=product/category&path=59 Yes took a look. Very cheap and some good stuff there.
mwhouston Posted February 17, 2016 Author Posted February 17, 2016 I suppose my latest DIY speakers belong here. Beyma 15" drivers in 170ltr dual ported enclosure. 99db efficient, Xover at 1600hz, 2nd order on the woofer and 3rd order on the tweeter. By ear I have tested bass down to 40hz. Very little at 31hz and lower. Room node at 63hz gives a nice little boost just as the bass starts to roll off. Yet to be painted probably a dark brown at this point, wife's choice. 2
Dean Gale Posted February 17, 2016 Posted February 17, 2016 Red goes faster. Sent from my SM-T113 using Tapatalk
jamiebosco Posted February 17, 2016 Posted February 17, 2016 I suppose my latest DIY speakers belong here. Beyma 15" drivers in 170ltr dual ported enclosure. 99db efficient, Xover at 1600hz, 2nd order on the woofer and 3rd order on the tweeter. By ear I have tested bass down to 40hz. Very little at 31hz and lower. Room node at 63hz gives a nice little boost just as the bass starts to roll off. Yet to be painted probably a dark brown at this point, wife's choice. Nice! If you don't mind me asking, approximately how much did these set you back to build (rough ballpark is fine)? I'd like a nice simple (and efficient!) 10" -15" coax speaker for surrounds,though something a bit smaller than this would be needed as they would need to be moved when not in use Cheers Jamie 1
mwhouston Posted February 17, 2016 Author Posted February 17, 2016 Nice! If you don't mind me asking, approximately how much did these set you back to build (rough ballpark is fine)? I'd like a nice simple (and efficient!) 10" -15" coax speaker for surrounds,though something a bit smaller than this would be needed as they would need to be moved when not in use Cheers Jamie About $2.5K so far.
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