Sub recommendations for multi-sub system ?
- By DBMandrake
- Subwoofers
- 41 Replies
Hi All,
I wonder if I could get a bit of input from people on trying to choose a model of subwoofer that would be suitable for use in a Geddes style multi-sub system where the primary purpose of the subwoofers is modal smoothing in the room for music playback rather than the typical home theatre "one giant sub to shake your house" approach that many subwoofers seem to be designed for.
Those who've read my posts before know I love ground up speaker design and currently have a new 3 way design in progress, (although semi on-hold due to circumstances outside my control) however for whatever reason I have zero interest in designing and building my own powered subwoofer, let alone the time to do it when I can't even find time to progress my 3 way design.
The main speakers which will (one day) be my main system are going to be a large floor standing 110(ish) litre bass reflex 3 way system - 12" woofer, 8" full range driver for midrange and ribbon tweeter.
In terms of bass response these will be tuned to around 25Hz and will have an early gradual roll-off alignment that will give a response that is about 6dB down at 25Hz before room gain is factored in, in short these should be good down to at least 25Hz in-room probably a bit lower and at a reasonably high SPL, as the ports will provide significant loading and gain vs sealed from around 20-40Hz.
So I won't need subwoofers to supplement the low end response of these speakers nor maximum SPL, however I will benefit from subwoofers to help with modal smoothing, as there are significant standing wave/boundary cancellation issues in this room that I can't do anything about passively, and speaker/listener positioning is extremely constrained by the size of the room and other stuff in the room.
It's a small British living room with a bay window on one end and the main sofa directly against the back wall. The front to back wall is 4.3 metres (hence the 40Hz fundamental mode) sideways its 3.8 metres, but 4.5 metres if you include the bay window in the left hand wall from the listener perspective. On the right hand wall is a 2 seat sofa and in the bay window there is a chair.
To its benefit we have high 2.8 metre ceilings, which does seem to help a bit with acoustics at higher frequencies and increases the room volume significantly for the small footprint.
The internal and external walls are all solid brick and plaster so not good for standing waves however the floor is a beam suspended wooden floor (with nearly a metre of crawl space and then dirt below) with carpet and the ceiling is gyprock / plasterboard suspended from wooden beams with some loft space above it and a second suspended wooden floor over parts of it as well.
So while the walls are bad for standing waves the floor and ceiling are probably quite good. Standing waves are still an issue but not as bad as a previous house I lived in with brick walls and carpet over a concrete floor which was really problematic...
The 2 way speakers I have at the moment only go down to around 40Hz and unlike the eventual 3 way design to replace them have the woofers high off the floor, which tends to exacerbate boundary cancellation issues.
The main issues I have are:
1) Large peak at 41Hz on the order of around 10dB at the listening position that has to be pulled way down with a PEQ, which then causes a hole at that frequency in other locations in the room. To fix this I probably need at least one subwoofer on the back (listener) wall to cancel the fundamental mode since a woofer in phase at the back wall would reduce the response at the back wall by the listener but increase it in the middle and most other locations in the room.
2) About a 6dB peak at 71Hz which I likewise pull down with a PEQ. I presume this is something to do with the ceiling reflection but I haven't really tried to work it out.
3) A big hole around 80-90Hz - almost complete cancellation at the listening position, and this is one of the things I'd really like to address with a multi-sub configuration as I can't do anything about it with EQ.
4) A nasty peak at around 105Hz which makes bass sound congested if I don't correct it with EQ.
5) A large depression right from 120Hz to 180Hz or so presumably due to boundary cancellation from the wall/corner behind the speakers, and I assume this would only be correctable by a subwoofer relatively close to the main speakers (due to the high frequency) such as the front right corner of the room about a metre from the main right speaker.
This depression can cause a lack of warmth on some material especially if I fully correct the nearby peak because there is not much energy between 100-200Hz once that 105Hz peak is corrected. (As a result I only partially correct the 105Hz peak until it doesn't sound congested to avoid losing all warmth in the upper bass) I would really like to do something about this depression in the 100-200Hz range.
Interestingly because the bay window makes the room asymmetrical no matter where you put the speakers, (in this room orientation) there is a big difference in the boundary cancellation of the left and right speakers. This was measured at the sofa at ear height with no gating so ignore anything above 200Hz:
As can be seen the left speaker (red) suffers considerably more severe cancellation (including 55Hz, 130Hz etc) than the right speaker or the summed response. This can sound a bit weird when a note at 130Hz is coming primarily from the right speaker for instance.
There are only really 3 places subwoofers could fit and work in with the furnishings.
One is to the left of the sofa where there is a 50cm gap to the wall which currently has a 45cm high table for a lamp, pot plant, remote controls etc, so a subwoofer of around 45x45x45 cm would fit there if it had a flat, wood grain top which could double as a table. (Egg shaped subwoofers need not apply)
The second possible location is in the far right corner near the right speaker, where there is a fair bit of room now that a toy chest is gone. It might have to have a pot plant standing on it as well...
The third possible location is to the right of the speaker part way up the right wall beside the side sofa. This one could be no bigger than about 40cm x 40cm x 40cm to fit under a small table that is there and clear the door.
So, what models to consider ? I'm not looking for a large sub home theatre style, several smaller subs with the same combined output of one large sub are much more suited to the multi-sub approach.
While I only want to buy one for now so I can make a useful improvement to the cancellation / bass issues I'm having with the current 2 way system and use it as a testing tool to measure the performance of different locations in the room, it needs to be cheap enough that I can afford eventually increasing the number of subs to 3, both for use with the current 2 way system and ultimately with the new 3 way system.
Features I'm looking for - discrete box shaped sub with a flat top surface that is either black or wood grained suitable for putting a plant on top of etc, and preferably with either a cover over the woofer or down facing woofer to make it look discrete. There needs be at least one side that doesn't have any controls and is either blank or has a cover over the woofer for aesthetics and also protection from an inquisitive 5 year old.
Adjustable low pass frequency, level, phase and auto-sensing power on. More advanced EQ would be nice but I doubt anything in my budget range would have that.
I already have a DEQ2496 on the system for overall EQ so after sub level matching, low pass filter settings, phase etc are all optimised as much as possible I can "clean up" the remaining bass balance with the DEQ2496.
I know pretty much nothing about what's out there in commercial subs and most of the reviews I've looked at are written for lay people by people that don't have any technical knowledge of speakers themselves so I'm hoping that I can get a few pointers of where to start looking...
I wonder if I could get a bit of input from people on trying to choose a model of subwoofer that would be suitable for use in a Geddes style multi-sub system where the primary purpose of the subwoofers is modal smoothing in the room for music playback rather than the typical home theatre "one giant sub to shake your house" approach that many subwoofers seem to be designed for.
Those who've read my posts before know I love ground up speaker design and currently have a new 3 way design in progress, (although semi on-hold due to circumstances outside my control) however for whatever reason I have zero interest in designing and building my own powered subwoofer, let alone the time to do it when I can't even find time to progress my 3 way design.
The main speakers which will (one day) be my main system are going to be a large floor standing 110(ish) litre bass reflex 3 way system - 12" woofer, 8" full range driver for midrange and ribbon tweeter.
In terms of bass response these will be tuned to around 25Hz and will have an early gradual roll-off alignment that will give a response that is about 6dB down at 25Hz before room gain is factored in, in short these should be good down to at least 25Hz in-room probably a bit lower and at a reasonably high SPL, as the ports will provide significant loading and gain vs sealed from around 20-40Hz.
So I won't need subwoofers to supplement the low end response of these speakers nor maximum SPL, however I will benefit from subwoofers to help with modal smoothing, as there are significant standing wave/boundary cancellation issues in this room that I can't do anything about passively, and speaker/listener positioning is extremely constrained by the size of the room and other stuff in the room.
It's a small British living room with a bay window on one end and the main sofa directly against the back wall. The front to back wall is 4.3 metres (hence the 40Hz fundamental mode) sideways its 3.8 metres, but 4.5 metres if you include the bay window in the left hand wall from the listener perspective. On the right hand wall is a 2 seat sofa and in the bay window there is a chair.
To its benefit we have high 2.8 metre ceilings, which does seem to help a bit with acoustics at higher frequencies and increases the room volume significantly for the small footprint.
The internal and external walls are all solid brick and plaster so not good for standing waves however the floor is a beam suspended wooden floor (with nearly a metre of crawl space and then dirt below) with carpet and the ceiling is gyprock / plasterboard suspended from wooden beams with some loft space above it and a second suspended wooden floor over parts of it as well.
So while the walls are bad for standing waves the floor and ceiling are probably quite good. Standing waves are still an issue but not as bad as a previous house I lived in with brick walls and carpet over a concrete floor which was really problematic...
The 2 way speakers I have at the moment only go down to around 40Hz and unlike the eventual 3 way design to replace them have the woofers high off the floor, which tends to exacerbate boundary cancellation issues.
The main issues I have are:
1) Large peak at 41Hz on the order of around 10dB at the listening position that has to be pulled way down with a PEQ, which then causes a hole at that frequency in other locations in the room. To fix this I probably need at least one subwoofer on the back (listener) wall to cancel the fundamental mode since a woofer in phase at the back wall would reduce the response at the back wall by the listener but increase it in the middle and most other locations in the room.
2) About a 6dB peak at 71Hz which I likewise pull down with a PEQ. I presume this is something to do with the ceiling reflection but I haven't really tried to work it out.
3) A big hole around 80-90Hz - almost complete cancellation at the listening position, and this is one of the things I'd really like to address with a multi-sub configuration as I can't do anything about it with EQ.
4) A nasty peak at around 105Hz which makes bass sound congested if I don't correct it with EQ.
5) A large depression right from 120Hz to 180Hz or so presumably due to boundary cancellation from the wall/corner behind the speakers, and I assume this would only be correctable by a subwoofer relatively close to the main speakers (due to the high frequency) such as the front right corner of the room about a metre from the main right speaker.
This depression can cause a lack of warmth on some material especially if I fully correct the nearby peak because there is not much energy between 100-200Hz once that 105Hz peak is corrected. (As a result I only partially correct the 105Hz peak until it doesn't sound congested to avoid losing all warmth in the upper bass) I would really like to do something about this depression in the 100-200Hz range.
Interestingly because the bay window makes the room asymmetrical no matter where you put the speakers, (in this room orientation) there is a big difference in the boundary cancellation of the left and right speakers. This was measured at the sofa at ear height with no gating so ignore anything above 200Hz:
As can be seen the left speaker (red) suffers considerably more severe cancellation (including 55Hz, 130Hz etc) than the right speaker or the summed response. This can sound a bit weird when a note at 130Hz is coming primarily from the right speaker for instance.
There are only really 3 places subwoofers could fit and work in with the furnishings.
One is to the left of the sofa where there is a 50cm gap to the wall which currently has a 45cm high table for a lamp, pot plant, remote controls etc, so a subwoofer of around 45x45x45 cm would fit there if it had a flat, wood grain top which could double as a table. (Egg shaped subwoofers need not apply)
The second possible location is in the far right corner near the right speaker, where there is a fair bit of room now that a toy chest is gone. It might have to have a pot plant standing on it as well...
The third possible location is to the right of the speaker part way up the right wall beside the side sofa. This one could be no bigger than about 40cm x 40cm x 40cm to fit under a small table that is there and clear the door.
So, what models to consider ? I'm not looking for a large sub home theatre style, several smaller subs with the same combined output of one large sub are much more suited to the multi-sub approach.
While I only want to buy one for now so I can make a useful improvement to the cancellation / bass issues I'm having with the current 2 way system and use it as a testing tool to measure the performance of different locations in the room, it needs to be cheap enough that I can afford eventually increasing the number of subs to 3, both for use with the current 2 way system and ultimately with the new 3 way system.
Features I'm looking for - discrete box shaped sub with a flat top surface that is either black or wood grained suitable for putting a plant on top of etc, and preferably with either a cover over the woofer or down facing woofer to make it look discrete. There needs be at least one side that doesn't have any controls and is either blank or has a cover over the woofer for aesthetics and also protection from an inquisitive 5 year old.
Adjustable low pass frequency, level, phase and auto-sensing power on. More advanced EQ would be nice but I doubt anything in my budget range would have that.
I already have a DEQ2496 on the system for overall EQ so after sub level matching, low pass filter settings, phase etc are all optimised as much as possible I can "clean up" the remaining bass balance with the DEQ2496.
I know pretty much nothing about what's out there in commercial subs and most of the reviews I've looked at are written for lay people by people that don't have any technical knowledge of speakers themselves so I'm hoping that I can get a few pointers of where to start looking...
Attachments
Polk power port technology. Does it really work
- Multi-Way
- 23 Replies
I came across Polk power port technology they use in some subwoofer and speakers.
Found this discussion online. Wanted to hear what people think about it and why is it not used by other manufacturers if it's such a great idea
Looking to use it instead of a port in a 2 way bookshelf speaker with 2 midbasses and a tweeter.
Found this discussion online. Wanted to hear what people think about it and why is it not used by other manufacturers if it's such a great idea
Looking to use it instead of a port in a 2 way bookshelf speaker with 2 midbasses and a tweeter.
Cello Audio Palette
- By Nrik
- Analog Line Level
- 112 Replies
Cello Audio Palette clone - My Photo Gallery
For years I have dreamt about this beautiful and versatile preamplifier.
However the pricetag of some 16-17.000 $ used on ebay + transport from the US kind of kept me from it.
So what other thing could I do than clone it.
The Audio Palette
The Cello Audio Palette was a six-band equalizer that came alone or with a build-in preamplifier.
It was the based on Richard Burwen many years of experience with equalizing, and was introduced as the only high-end equalizer. The Cello brand was Mark Levinsons comeback after being thrown out of ...Mark Levinson.
Now equalizers were not – and are still not – considered to be a component that belongs in a high-end system. (This is probably the reason why Cello chose to call it an Audio Palette and not an equalizer). Music lovers (thinks they) want the pure and clean original sound, and do not want to add any un-necessary circuits into the signal path, which might introduce more distortion and noise.
But first of all – this one was different.
Besides it was actually Mark levinson that invented the no-nonsense line, by removing bass and treble potentiometers from his amplifiers. However not many people know the actual reason, but in an interview Mark Levinson said:
” Even though Levinson pioneered the 'straight line purist approach' to audio, he feels that despite the extra path that the signal must pass through, the advantages of the Audio Palette far outweigh the disadvantages. "A purist philosophy does not mean fewer dials. I am not of the purist philosophy - I founded it! I never said that equalizers were bad, I just said that we don't know any that are any good.
"In our previous experience, whenever we put an equaliser into the system, it sounded worse. The Audio Palette is not simply an equaliser, it is a far more complex product than that and the objective is essentially the idea of music restoration. The ability to restore the quality to approximate lifelike sound is different from the design objective of most equalisers which is to allow the engineer the ability to adjust the sound to create a variety of effects. The Audio Palette is userfriendly, anyone can learn to use it in a few minutes and you don't have to be an engineer when you want to restore music. If you don't want to restore music then u are stuck with either listening to bad sound or playing recordings that your system likes to play and 1 don't think that it is a state of the art concept - to spend a lot of money to listen to six records and 2 compact discs."
When you read it, you just realize how true it is.
Okay so how did this Audio Palette achieve the magic goal of adjusting the sound without ruining the sound quality?
First and most important of all, the equalizing part is genious, no really ...GENIOUS!
Instead having a heap of 10 to 31 bands there are only six. Exactly enough to be able to adjust detailed enough for making most bad recordings sound great, and at the same time very easy to operate. This matters a lot, because if one have to go through maybe 31 bands for adjusting the sound, it might be easier just not to do it.
Besides the Q of each band is 0.7 which is a quite soft slope for an equalizer. Normal EQs operate with a Q up to 4 ! This will seriously impact the impulse response, where a low Q of 0,7 is equal to a first-order filter and is quite gentle with the signal.
And to make it even more brilliant the range of each band is wieghted against the human hearing. So in the two mid-bands where your ears are most sensitive, the maximum range is +/-6dB, the two bands on each side, operating in an area where your ears are a little less sensitive, the range is +/-12dB, and finally the two outer controls ( 20Hz and 20kHz) where your ears really needs a kick to tell the difference the range is +/-22dB.
The result is, that even if you dont know anything about deciBel and Herz, you actually feel that the six bands have exactly the same level of impact to the sound, in each their frequency range. Again: very easy to adjust, quite logical function-wise, and it is strange that no-one else has ever made it like this.
The Original
Being a high-end product and to ensure the Audio Palette didn’t add noise and distortion, the circuitry was ofcourse very special. The inside of the huge cabinet was packed with 20-some individual PCBs with discrete class-A modules (power consumption was 100Watt – quite a lot for a preamp!), top-of-the-range components for that era, separate power supply, and some very impressive rotary switches for most of the dials. Use Google for pictures of the whole shabang – very impressive!
Later Cello introduced a lower priced ”Palette Preamplifier” which was buildt with opamps and vishay pots.
My build
All right enough about the original. I might seem suspiciously extatic about it, but I have no economic interests in Cello, or any intend to hype this product for personal gain, I am just simply amazed by the function and the geniousness of this machine – hence as a DIY-lunatic I simply had to clone it.😀
I started out with making an equalizer that wasn’t a true copy, but which did exactly the same fitted with standard pots.
I used Rod Elliots discription of Ranes constant-Q EQ circuit, which must be very similar to the concept. I was amazed of how well it worked, and really enjoyed the possibility to adjust the sound. I have CDs which are almost unbearable to listen to without eq, but simply turns into magic when I turn a few dials. Suddenly I could enjoy some fantastic music which I couldn’t before.
Allright so I was hooked, and the looks on the original is also just up my alley. So a lot of surfing went into finding the right knobs ( got them on ebay from Hong Kong), and a drawing for the cabinet was sent to modushop/hifi2000 in Italy.
I also did a lot of surfing to find some nice rotary switches. The original had some very nice in-house made 59 position ones, and the closest thing would be a Glasshouse 43 pos but they are quite pricey. Eventually I found some used 26 pos On ebay, which I bought a bunch of. It took me quite some time to clean them and to solder resistors to make linear attenuators from them.
Future plans
So here I am, I would say 2/3 finished, but with a working unit. The EQ board and the preamp part are made with OPA2134 and TL084 opamps on veroboards. They work, and has decent sound quality. But ofcourse I wil at some point replace the circuitry with somenthing more elegant. I have done some reverse-engineering of the original modules based on pctures, but my personal taste in circuits goes in another direction, I am thinking discrete J-fet opamps on real PCBs. The input relay board is scavenged from a autostereo demoboard.
Anyway: I have the cabinet and the switches as I want them to be, so I am going to:
a) Put some text on the knobs
b) Make a remote control circuit of volume and input selection
c) Eventually replace the circuits inside.
...But I just felt like sharing allready at this stage.
Questions? ...just shoot.😎
All the best from Henrik
For years I have dreamt about this beautiful and versatile preamplifier.
However the pricetag of some 16-17.000 $ used on ebay + transport from the US kind of kept me from it.
So what other thing could I do than clone it.
The Audio Palette
The Cello Audio Palette was a six-band equalizer that came alone or with a build-in preamplifier.
It was the based on Richard Burwen many years of experience with equalizing, and was introduced as the only high-end equalizer. The Cello brand was Mark Levinsons comeback after being thrown out of ...Mark Levinson.
Now equalizers were not – and are still not – considered to be a component that belongs in a high-end system. (This is probably the reason why Cello chose to call it an Audio Palette and not an equalizer). Music lovers (thinks they) want the pure and clean original sound, and do not want to add any un-necessary circuits into the signal path, which might introduce more distortion and noise.
But first of all – this one was different.
Besides it was actually Mark levinson that invented the no-nonsense line, by removing bass and treble potentiometers from his amplifiers. However not many people know the actual reason, but in an interview Mark Levinson said:
” Even though Levinson pioneered the 'straight line purist approach' to audio, he feels that despite the extra path that the signal must pass through, the advantages of the Audio Palette far outweigh the disadvantages. "A purist philosophy does not mean fewer dials. I am not of the purist philosophy - I founded it! I never said that equalizers were bad, I just said that we don't know any that are any good.
"In our previous experience, whenever we put an equaliser into the system, it sounded worse. The Audio Palette is not simply an equaliser, it is a far more complex product than that and the objective is essentially the idea of music restoration. The ability to restore the quality to approximate lifelike sound is different from the design objective of most equalisers which is to allow the engineer the ability to adjust the sound to create a variety of effects. The Audio Palette is userfriendly, anyone can learn to use it in a few minutes and you don't have to be an engineer when you want to restore music. If you don't want to restore music then u are stuck with either listening to bad sound or playing recordings that your system likes to play and 1 don't think that it is a state of the art concept - to spend a lot of money to listen to six records and 2 compact discs."
When you read it, you just realize how true it is.
Okay so how did this Audio Palette achieve the magic goal of adjusting the sound without ruining the sound quality?
First and most important of all, the equalizing part is genious, no really ...GENIOUS!
Instead having a heap of 10 to 31 bands there are only six. Exactly enough to be able to adjust detailed enough for making most bad recordings sound great, and at the same time very easy to operate. This matters a lot, because if one have to go through maybe 31 bands for adjusting the sound, it might be easier just not to do it.
Besides the Q of each band is 0.7 which is a quite soft slope for an equalizer. Normal EQs operate with a Q up to 4 ! This will seriously impact the impulse response, where a low Q of 0,7 is equal to a first-order filter and is quite gentle with the signal.
And to make it even more brilliant the range of each band is wieghted against the human hearing. So in the two mid-bands where your ears are most sensitive, the maximum range is +/-6dB, the two bands on each side, operating in an area where your ears are a little less sensitive, the range is +/-12dB, and finally the two outer controls ( 20Hz and 20kHz) where your ears really needs a kick to tell the difference the range is +/-22dB.
The result is, that even if you dont know anything about deciBel and Herz, you actually feel that the six bands have exactly the same level of impact to the sound, in each their frequency range. Again: very easy to adjust, quite logical function-wise, and it is strange that no-one else has ever made it like this.
The Original
Being a high-end product and to ensure the Audio Palette didn’t add noise and distortion, the circuitry was ofcourse very special. The inside of the huge cabinet was packed with 20-some individual PCBs with discrete class-A modules (power consumption was 100Watt – quite a lot for a preamp!), top-of-the-range components for that era, separate power supply, and some very impressive rotary switches for most of the dials. Use Google for pictures of the whole shabang – very impressive!
Later Cello introduced a lower priced ”Palette Preamplifier” which was buildt with opamps and vishay pots.
My build
All right enough about the original. I might seem suspiciously extatic about it, but I have no economic interests in Cello, or any intend to hype this product for personal gain, I am just simply amazed by the function and the geniousness of this machine – hence as a DIY-lunatic I simply had to clone it.😀
I started out with making an equalizer that wasn’t a true copy, but which did exactly the same fitted with standard pots.
I used Rod Elliots discription of Ranes constant-Q EQ circuit, which must be very similar to the concept. I was amazed of how well it worked, and really enjoyed the possibility to adjust the sound. I have CDs which are almost unbearable to listen to without eq, but simply turns into magic when I turn a few dials. Suddenly I could enjoy some fantastic music which I couldn’t before.
Allright so I was hooked, and the looks on the original is also just up my alley. So a lot of surfing went into finding the right knobs ( got them on ebay from Hong Kong), and a drawing for the cabinet was sent to modushop/hifi2000 in Italy.
I also did a lot of surfing to find some nice rotary switches. The original had some very nice in-house made 59 position ones, and the closest thing would be a Glasshouse 43 pos but they are quite pricey. Eventually I found some used 26 pos On ebay, which I bought a bunch of. It took me quite some time to clean them and to solder resistors to make linear attenuators from them.
Future plans
So here I am, I would say 2/3 finished, but with a working unit. The EQ board and the preamp part are made with OPA2134 and TL084 opamps on veroboards. They work, and has decent sound quality. But ofcourse I wil at some point replace the circuitry with somenthing more elegant. I have done some reverse-engineering of the original modules based on pctures, but my personal taste in circuits goes in another direction, I am thinking discrete J-fet opamps on real PCBs. The input relay board is scavenged from a autostereo demoboard.
Anyway: I have the cabinet and the switches as I want them to be, so I am going to:
a) Put some text on the knobs
b) Make a remote control circuit of volume and input selection
c) Eventually replace the circuits inside.
...But I just felt like sharing allready at this stage.
Questions? ...just shoot.😎
All the best from Henrik
12AT7 Made in GDR
- By jcalvarez
- Tubes / Valves
- 4 Replies
It's the first time I see a tube made in GDR. Are those good, I mean a proper 12AT7 copy?
Can anybody identify this subwoofer?
- By agk_72
- Subwoofers
- 6 Replies
Need help identifying this. I can’t find anything about it online. Thanks.
Aleph J Finished
Just finished building/testing and now amp has been playing on and off for about 6 hours or so trying various types of music.
My first impression after connecting all input/output cables and switching on was one of disappointment as i couldn't hear a thing from either speaker, (even with volume turned high), literally dead silence, and thinking major trouble shooting ahead, having been accustomed in the past after building numerous tube amps with varying degrees of normally very low but audible hum, however after turning volume control back down and pressing play button, then slowly increasing again only music came from the speakers from a background of black silence, i was gob smacked!
It’s this silent background that seems to make the actual music stand out with such great resolution, this is a superb amp so thumbs up to Mr Pass for making it available to us Jo Public amateur builders.👍👍👍
I have made a few notes and attachments which might be of interest to other builders:
I used EasyEDA software for drawing the schematic and designing the PCB layouts, the gerber files can be exported and you can order the PCBs directly through the Easy EDA programme.
https://easyeda.com/
The minimum quantity is 5 boards for each design (good to have extra in case of soldering mistakes), they are cheap and good quality, just make sure to get the design you want before committing to order, check and re-check all component spacing, dimensions and hole diameters.
This was the first time I used this programme but after a little while it is easy to work with and good fun.
The below schematic is the one i used after re-drawing it in EasyEDA, the only change would be to leave out R7 fixed resistor and just have the R7 trim pot because with the R7 fixed resistor in place there is insufficient adjustment to reduce the offset.
![IMG_5445[1].JPG](https://www.diyaudio.com/community/attachments/img_5445-1-jpg.1053847/ "IMG_5445[1].JPG")
The same goes for the PSU board, you can design it any way you want to suit your own needs/budget, the attached PSU schematic is for one channel.
The chassis was ordered from Aliexpress, China and although it took a while to arrive it came well packed and of excellent quality, it can be completely disassembled so drilling and tapping etc is easily done and board/component installation also very easy, no complaints at all:
Brzhifi Bz4315a Double Radiator Aluminum Case For Power Amplifier - Home Theater Amplifiers - AliExpress
The MOSFETS/JFETS came from DIYaudio, the rest of the components mainly Mouser, there are plenty of lists/advice on forum on what to use.
The build was straight forward once I was confident with the PCB design, the only problem I had was adjusting the offset due to the addition of the fixed R7 which I mentioned earlier (this was my error due to the interpretation of original schematic I used), as soon as I removed it the offset was easily adjustable to zero and the bias likewise to 400mV.
Not much more to say really, like i said I've built quite a few tube amps in the past including a pair of 300B monoblocks which i thought up till now would never be beat, but this is right up there., thanks again Mr Pass.
My first impression after connecting all input/output cables and switching on was one of disappointment as i couldn't hear a thing from either speaker, (even with volume turned high), literally dead silence, and thinking major trouble shooting ahead, having been accustomed in the past after building numerous tube amps with varying degrees of normally very low but audible hum, however after turning volume control back down and pressing play button, then slowly increasing again only music came from the speakers from a background of black silence, i was gob smacked!
It’s this silent background that seems to make the actual music stand out with such great resolution, this is a superb amp so thumbs up to Mr Pass for making it available to us Jo Public amateur builders.👍👍👍
I have made a few notes and attachments which might be of interest to other builders:
I used EasyEDA software for drawing the schematic and designing the PCB layouts, the gerber files can be exported and you can order the PCBs directly through the Easy EDA programme.
https://easyeda.com/
The minimum quantity is 5 boards for each design (good to have extra in case of soldering mistakes), they are cheap and good quality, just make sure to get the design you want before committing to order, check and re-check all component spacing, dimensions and hole diameters.
This was the first time I used this programme but after a little while it is easy to work with and good fun.
The below schematic is the one i used after re-drawing it in EasyEDA, the only change would be to leave out R7 fixed resistor and just have the R7 trim pot because with the R7 fixed resistor in place there is insufficient adjustment to reduce the offset.
The same goes for the PSU board, you can design it any way you want to suit your own needs/budget, the attached PSU schematic is for one channel.
The chassis was ordered from Aliexpress, China and although it took a while to arrive it came well packed and of excellent quality, it can be completely disassembled so drilling and tapping etc is easily done and board/component installation also very easy, no complaints at all:
Brzhifi Bz4315a Double Radiator Aluminum Case For Power Amplifier - Home Theater Amplifiers - AliExpress
The MOSFETS/JFETS came from DIYaudio, the rest of the components mainly Mouser, there are plenty of lists/advice on forum on what to use.
The build was straight forward once I was confident with the PCB design, the only problem I had was adjusting the offset due to the addition of the fixed R7 which I mentioned earlier (this was my error due to the interpretation of original schematic I used), as soon as I removed it the offset was easily adjustable to zero and the bias likewise to 400mV.
Not much more to say really, like i said I've built quite a few tube amps in the past including a pair of 300B monoblocks which i thought up till now would never be beat, but this is right up there., thanks again Mr Pass.
Cambridge SoundWorks Newton T500 Class D: Help to ID & Fix Design Flaw?
Hi Everyone,
I'm looking for help reverse engineering the Class D amp in a pair of Cambridge SoundWorks Newton T500 speakers I acquired in order to identify and fix any design flaws that may exist. Searching online for these speakers yields numerous complaints (namely on the AVS Forum) that the OEM amp design fails routinely in couple-year intervals. The company does offer a replacement service for mucho dinero and is unsurprisingly tight lipped about any faults / schematics or any help to DIY (no idea which company actually makes/supplies the amp).
Given the routine failures, even of the replacement amps, I imagine there must be a design flaw in here somewhere. Maybe one, maybe several components are underspec'd? Maybe it's the MOSFETs? Maybe something else.
Problem is - I'm a mechanical engineer, not an electrical engineer, so I'm a bit out of my league. I'm posting here hoping for some help and of course hoping to learn more about how Class D amps work and how I could go about diagnosing this on my own. Apologies in advance if I'm missing any threads I should I have read - I did search high and low for previous threads about repairing these amps and found nothing.
Below are a bunch of pics of the speaker and the amp in question. You'll see it's a 4 way design. The powered 10" sub and 12" PR are on the side of the enclosure, and the mid-bass/mid/tweeter are on the front. The sub input comes in directly to the plate amp, then through an adjustable low pass crossover and sub level pot to the sub. The high-level input seems to pass directly through the plate amp, to the passive crossover inside the cabinet, and on to the mid-bass/mid/tweeter.
Thanks in advance for any help!
Ryan
I'm looking for help reverse engineering the Class D amp in a pair of Cambridge SoundWorks Newton T500 speakers I acquired in order to identify and fix any design flaws that may exist. Searching online for these speakers yields numerous complaints (namely on the AVS Forum) that the OEM amp design fails routinely in couple-year intervals. The company does offer a replacement service for mucho dinero and is unsurprisingly tight lipped about any faults / schematics or any help to DIY (no idea which company actually makes/supplies the amp).
Given the routine failures, even of the replacement amps, I imagine there must be a design flaw in here somewhere. Maybe one, maybe several components are underspec'd? Maybe it's the MOSFETs? Maybe something else.
Problem is - I'm a mechanical engineer, not an electrical engineer, so I'm a bit out of my league. I'm posting here hoping for some help and of course hoping to learn more about how Class D amps work and how I could go about diagnosing this on my own. Apologies in advance if I'm missing any threads I should I have read - I did search high and low for previous threads about repairing these amps and found nothing.
Below are a bunch of pics of the speaker and the amp in question. You'll see it's a 4 way design. The powered 10" sub and 12" PR are on the side of the enclosure, and the mid-bass/mid/tweeter are on the front. The sub input comes in directly to the plate amp, then through an adjustable low pass crossover and sub level pot to the sub. The high-level input seems to pass directly through the plate amp, to the passive crossover inside the cabinet, and on to the mid-bass/mid/tweeter.
Thanks in advance for any help!
Ryan
Free: 4 VISATON W 200 S woofers
- By bourbon-neat
- Swap Meet
- 10 Replies
I have four unused VISATON W 200 S woofers. Free with pickup in San Jose, CA. Or, free you pay shipping.
Free: Tymphany LAT 250 woofer pair
- By bourbon-neat
- Swap Meet
- 5 Replies
I have a pair of unused Tymphany LAT250 woofers. Free with pickup in San Jose, CA. Or, free you pay shipping.
Designing a Voice Coil - How do you calculate or estimate such parameters?
- By weiberheld
- Multi-Way
- 3 Replies
Okay, now I know, for example, what kind of Xmax value I want to achieve and what kind of material I want to use for the voice coil, but how do I put the rest together?
powerpod 740 help needed
- By unclefester
- Solid State
- 47 Replies
Hi,
Anyone know were i can get a service manual or schematics for a phonic powerpod 740 deluxe ?
my amp went 'bang' the other night and i need to replace a few bits ...
Cheers
Dave
Anyone know were i can get a service manual or schematics for a phonic powerpod 740 deluxe ?
my amp went 'bang' the other night and i need to replace a few bits ...
Cheers
Dave
Op-Amp recommendation for replacing/upgrading I/V and LPF in a dac
- By kazuviking
- Parts
- 8 Replies
Hello there. I have a cheap chinese dac (D2-mini) and wanna experiment with different op-amps. Currently it uses 2 NE5532P as the I/V and a TL072 as the LPF.
Current planned replacement NJM2137D for the I/V and AD8066ADR for the LPF. The LME49720NA is disqualified as the LPF because its 5V performance is horrible, 1%thd+n at 2vrms output. I'm looking for any op-amp recommendation that is not super expensive.
Dac internals.
Current planned replacement NJM2137D for the I/V and AD8066ADR for the LPF. The LME49720NA is disqualified as the LPF because its 5V performance is horrible, 1%thd+n at 2vrms output. I'm looking for any op-amp recommendation that is not super expensive.
Dac internals.
Frank (Radio Union) Hi.Fi. sy stereo tuner
- By irondutchess
- Tubes / Valves
- 8 Replies
I have a Frank Hi.Fi. by (Stereo?) tuner manufactured in Belgium around 1961. I am looking for service data on realignment. There is no information plate on the unit, the only info is on the front panel.
Here is the only info I have on the manufacturer:
Mr Maurice Frank was engineer from Telefunken Brussels before the war, after the war he started up his own company "Radio Union" mid 50s he started with HiFi amplifiers and tuners.
The problem is, when tuning into stations you can get the left or right channel tuned in clearly, but not both. I am guessing that some form of realignment is required, but to do this I assume would require some data to work from. I live in Cornwall UK, (long shot) does anyone know someone in the area that does this kind of work?
Any help would be appreciated
Chris
I also have the matching amplifier. https://www.diyaudio.com/community/...ts-ultra-linear-stereo-tube-amplifier.368539/
Here is the only info I have on the manufacturer:
Mr Maurice Frank was engineer from Telefunken Brussels before the war, after the war he started up his own company "Radio Union" mid 50s he started with HiFi amplifiers and tuners.
The problem is, when tuning into stations you can get the left or right channel tuned in clearly, but not both. I am guessing that some form of realignment is required, but to do this I assume would require some data to work from. I live in Cornwall UK, (long shot) does anyone know someone in the area that does this kind of work?
Any help would be appreciated
Chris
I also have the matching amplifier. https://www.diyaudio.com/community/...ts-ultra-linear-stereo-tube-amplifier.368539/
Decca London Ribbon
Hi I’ve just bought a par of Decca London Ribbon and would love some help to build a nice speaker with the right filter, elements and box.
this is what I have now
And this is what I would like to have.
I am a real rookie so please help me out shase my dream 😁🔈
this is what I have now
And this is what I would like to have.
I am a real rookie so please help me out shase my dream 😁🔈
