Maximum choke size in LC input rectifier
- By force of 1/2
- Tubes / Valves
- 19 Replies
Hello All,
Is their a practical limit to the inductance of the choke used in a choke input filter after a rectifier?
I am trying to understand the attached graph for the max rating of an EZ81 using a choke input filter.
It seems to suggest that the larger the coke (in henries) used the lower the max output current rating is at a given voltage. I have never seen this mentioned before.
Am I just misinterpreting the graph?
Thank in advance for your advice.
Best regards,
John
Is their a practical limit to the inductance of the choke used in a choke input filter after a rectifier?
I am trying to understand the attached graph for the max rating of an EZ81 using a choke input filter.
It seems to suggest that the larger the coke (in henries) used the lower the max output current rating is at a given voltage. I have never seen this mentioned before.
Am I just misinterpreting the graph?
Thank in advance for your advice.
Best regards,
John
My Fostex FF85Wk in a ported boxes does it get any better?
- By Jeffrey 01
- Full Range
- 48 Replies
Attachments
Power supply for TDA7294 100w Amplifier
- By lcd950
- Power Supplies
- 12 Replies
Can I use 35VAC 0 35VAC (Rectifiered voltage +50VDC 0 -50VDC) Transformer for 2*TDA7294 100w Amplifier.Is this too much?
My original post http://www.diyaudio.com/forums/power-supplies/68726-power-supply-lm4702-2.html#post4690029
My original post http://www.diyaudio.com/forums/power-supplies/68726-power-supply-lm4702-2.html#post4690029
Attachments
Advice on a combination Loftin-White stereo and mic preamp?
- By sahazel
- Tubes / Valves
- 2 Replies
A friend of mine found a deal on parts to make a Loftin-White based, directly-coupled 6SL7 / 2A3 stereo amplifier, and brought it to me hoping it might make an interesting... mic preamp. I'm not so sure about that idea, but I told him I could build the stereo first, and would try my best to also make it usable as a mic preamp (with some additional parts), maybe more of an unusual character thing than anything very good.
So, for the stereo, I'm looking at two schematics that seem like interesting designs to explore, and which would use the parts I have:
(Schematics show one channel, but this is a stereo and I plan to build two channels.)
My problem now is that, while I can find plenty of mic pre schematics and some that use 6SL7s, I've never built something like this before (so far I've been tinkering with guitar amps) and don't really know what the important aspects of mic preamp design are. How much gain should I be aiming for? How do I choose suitable input and output transformers? What other concerns am I unaware of?
My first thought for the topology is to set up some switching to take both 6SL7 preamps out of the stereo, and connect them instead in push-pull on either end of the mic input and output transformers. Any advice on whether that's a good starting point?
I'm thinking capacitor-coupled designs would be more complicated because they'd require switching the last stages to act as cathode followers, but maybe that SRPP stereo design could work for something like that. Other options I suppose would include using just a single 6SL7 from one channel instead, or incorporating the 2A3s somehow.
So, for the stereo, I'm looking at two schematics that seem like interesting designs to explore, and which would use the parts I have:
(Schematics show one channel, but this is a stereo and I plan to build two channels.)
My problem now is that, while I can find plenty of mic pre schematics and some that use 6SL7s, I've never built something like this before (so far I've been tinkering with guitar amps) and don't really know what the important aspects of mic preamp design are. How much gain should I be aiming for? How do I choose suitable input and output transformers? What other concerns am I unaware of?
My first thought for the topology is to set up some switching to take both 6SL7 preamps out of the stereo, and connect them instead in push-pull on either end of the mic input and output transformers. Any advice on whether that's a good starting point?
I'm thinking capacitor-coupled designs would be more complicated because they'd require switching the last stages to act as cathode followers, but maybe that SRPP stereo design could work for something like that. Other options I suppose would include using just a single 6SL7 from one channel instead, or incorporating the 2A3s somehow.
Parts for repair of Open Back vintage Realistic Speaker.
- By CliffR52
- Full Range
- 11 Replies
Attachments
Dual 18SW115 BP6S with a "mid chamber", model approximation advice?
- By recon440
- Subwoofers
- 17 Replies
Hello everyone,
I'm looking for advice on most accurately modelling a 6th order enclosure. Currently I have a 6th order using two Alpine Type-R 12's but for the next season I've decided to go bigger and have chosen to employ two 18's and fitting them has introduced some unique geometrical constraints that I am not sure how to best approximate in Hornresp.
At a high level the object will be to play broadband 35Hz-100Hz at power levels ~1000W-3000W. I've decided to go with PA drivers this time because B&C 18SW115s came up at a steal of a price (~400CAD each, new). Additionally, they seem to best the the Type-Rs in all other categories; weight, power handling/compression, mid-band sensitivity, still have generous excursion capability.
As I've modelled and built 6th's well in the past I was hoping to model conventionally with the rear section firing forward (thus eliminating a mid chamber). Unfortunately after building the rear section it appears that am short 1" in terms of clearance to close the trunk, thus I have to lay the rear section flat and have the drivers firing downward which introduces some interesting considerations of having a mid-chamber (I guess turning this enclosure into technically an 8th order).
In nutshell, this system comprises of three sections in order to fit inside the trunk (will be sealed together using foam gaskets so they can be easily disassembled). The images I put together PPT below show the general configuration. The side-view I think most clearly shows the geometry of what I am dealing with.
(All values below are net after displacements, wood thickness is 0.75" MDF)
- Rear (yellow): ~104L: houses two B&C 18SW115s, two 22cm 4"ID PVCs, when considered standalone tunes to ~38Hz. The drivers are recessed in this chamber by 0.75" for speaker protection.
- Mid (blue): ~42L: a chamber with an open-top that serves a "pedestal" for which the rear chamber to fire into. In essence, the foot-print of this chamber is identical of the rear chamber that is mounted atop of it. The front of this chamber has an opening to where it mates to the front chamber; the opening here will be ~3"x29.5". This chamber is the crux of the problem as it has an effective axial area of ~895cm^2 (3.75"x37") over a length of 47cm which then steps into to front chamber having an aperture of 571cm^2 (3"*29.5").
- Front (red): ~136L: this chamber sleeves the inside portion of the trunk and mates up to the ski pass (~489cm^2 of port, ~2" in length but this can be adjusted as needed). From the top, the front chamber is slightly narrower than the rear/mid chambers.
Modeling is done in Hornresp, with 1kW of power, using semi-inductance parameters I've derived from the impedance curve. The volume of each section is quite trivial (~286L total in each model) but it seems that the geometry (in terms of length/areas) results in significant deviations from model to model. I would appreciate any advice on what would be most appropriate. The problem at hand is that I don't think I can bin the mid and front chambers and consider them simply in terms of volume as I think there are some compression effects happening in the mid-chamber.
Model 1: TH1 using a standard rear chamber, mid-chamber is approximated ~895cm^2 using two horn sections (this not account for the step change into a 29.5"*3" (571cm^2) aperture into the front chamber.
Model 2.1: TH1 using a standard rear chamber, mid-chamber is accounted for in Vtc/Atc; Atc is 4416cm^2 giving a length of 9.52cm, this loads into the front chamber through the 29.5"*3" aperture into the front chamber which is accounted for here
Model 2.2: TH1 using a standard rear chamber, mid-chamber is accounted for in Vtc/Atc; Atc is 895cm^2 giving a length of 47cm, this loads into the front chamber through the 29.5"*3" aperture into the front chamber which is accounted for here
There are a couple critical questions in regards to the models:
- Models 2.1 and 2.2 are quite similar with the difference being the consideration of the "length" of the chamber relative to everything else. Is it seen as 9.52cm (height) or 47cm long (length). I like these in that they both consider loading into the front chamber through the step change in the mid chamber but are quite different due to the considered length of the mid-chamber? What is most appropriate? Or maybe something in the middle, like a 24cm approximation of length.
- What is the most "correct" placement of the front and rear entry points? Effectively, I would like to have woofers and port as a single point loading in at 25cm (the center point of mid-chamber) but I don't think that it's possible to do with more segments, which I don't believe Hornresp supports. Given horn-resps constrains it seems that the driver and vents are offset by some distance which results in model differences between the two.
Model 3: BP8 Wizard where the mid-chamber step is considered as a 0.75" port of area 571cm^2. I think this one is the most ambiguous of what is happening in terms of geometry.
All in all, I think the responses in all models looks fairly workable in the frequency band I want to target but it would be nice to have a relatively flat response with slight emphasis at 40Hz (which model 2.1 presents).
As always, I would be very greatful for any advice and insights on this design.
I'm looking for advice on most accurately modelling a 6th order enclosure. Currently I have a 6th order using two Alpine Type-R 12's but for the next season I've decided to go bigger and have chosen to employ two 18's and fitting them has introduced some unique geometrical constraints that I am not sure how to best approximate in Hornresp.
At a high level the object will be to play broadband 35Hz-100Hz at power levels ~1000W-3000W. I've decided to go with PA drivers this time because B&C 18SW115s came up at a steal of a price (~400CAD each, new). Additionally, they seem to best the the Type-Rs in all other categories; weight, power handling/compression, mid-band sensitivity, still have generous excursion capability.
As I've modelled and built 6th's well in the past I was hoping to model conventionally with the rear section firing forward (thus eliminating a mid chamber). Unfortunately after building the rear section it appears that am short 1" in terms of clearance to close the trunk, thus I have to lay the rear section flat and have the drivers firing downward which introduces some interesting considerations of having a mid-chamber (I guess turning this enclosure into technically an 8th order).
In nutshell, this system comprises of three sections in order to fit inside the trunk (will be sealed together using foam gaskets so they can be easily disassembled). The images I put together PPT below show the general configuration. The side-view I think most clearly shows the geometry of what I am dealing with.
(All values below are net after displacements, wood thickness is 0.75" MDF)
- Rear (yellow): ~104L: houses two B&C 18SW115s, two 22cm 4"ID PVCs, when considered standalone tunes to ~38Hz. The drivers are recessed in this chamber by 0.75" for speaker protection.
- Mid (blue): ~42L: a chamber with an open-top that serves a "pedestal" for which the rear chamber to fire into. In essence, the foot-print of this chamber is identical of the rear chamber that is mounted atop of it. The front of this chamber has an opening to where it mates to the front chamber; the opening here will be ~3"x29.5". This chamber is the crux of the problem as it has an effective axial area of ~895cm^2 (3.75"x37") over a length of 47cm which then steps into to front chamber having an aperture of 571cm^2 (3"*29.5").
- Front (red): ~136L: this chamber sleeves the inside portion of the trunk and mates up to the ski pass (~489cm^2 of port, ~2" in length but this can be adjusted as needed). From the top, the front chamber is slightly narrower than the rear/mid chambers.
Modeling is done in Hornresp, with 1kW of power, using semi-inductance parameters I've derived from the impedance curve. The volume of each section is quite trivial (~286L total in each model) but it seems that the geometry (in terms of length/areas) results in significant deviations from model to model. I would appreciate any advice on what would be most appropriate. The problem at hand is that I don't think I can bin the mid and front chambers and consider them simply in terms of volume as I think there are some compression effects happening in the mid-chamber.
Model 1: TH1 using a standard rear chamber, mid-chamber is approximated ~895cm^2 using two horn sections (this not account for the step change into a 29.5"*3" (571cm^2) aperture into the front chamber.
Model 2.1: TH1 using a standard rear chamber, mid-chamber is accounted for in Vtc/Atc; Atc is 4416cm^2 giving a length of 9.52cm, this loads into the front chamber through the 29.5"*3" aperture into the front chamber which is accounted for here
Model 2.2: TH1 using a standard rear chamber, mid-chamber is accounted for in Vtc/Atc; Atc is 895cm^2 giving a length of 47cm, this loads into the front chamber through the 29.5"*3" aperture into the front chamber which is accounted for here
There are a couple critical questions in regards to the models:
- Models 2.1 and 2.2 are quite similar with the difference being the consideration of the "length" of the chamber relative to everything else. Is it seen as 9.52cm (height) or 47cm long (length). I like these in that they both consider loading into the front chamber through the step change in the mid chamber but are quite different due to the considered length of the mid-chamber? What is most appropriate? Or maybe something in the middle, like a 24cm approximation of length.
- What is the most "correct" placement of the front and rear entry points? Effectively, I would like to have woofers and port as a single point loading in at 25cm (the center point of mid-chamber) but I don't think that it's possible to do with more segments, which I don't believe Hornresp supports. Given horn-resps constrains it seems that the driver and vents are offset by some distance which results in model differences between the two.
Model 3: BP8 Wizard where the mid-chamber step is considered as a 0.75" port of area 571cm^2. I think this one is the most ambiguous of what is happening in terms of geometry.
All in all, I think the responses in all models looks fairly workable in the frequency band I want to target but it would be nice to have a relatively flat response with slight emphasis at 40Hz (which model 2.1 presents).
As always, I would be very greatful for any advice and insights on this design.
Attachments
best drum solo or recording?
- Music
- 130 Replies
Why should the guitarists be the only one recognized? Let's hear about your favorite drummer, drum solo, or outstanding drum recordings...
Favorite solo: Dave Weckl and Steve Gadd- title track to Weckl's cd "Master Plan". Both drummers playing on one track, alternating solos, panned slightly left and right. Not the best recording- completely overproduced, as are most of Dave's recordings, but great playing.
Anything by Vinnie Colaiuta...
NS
Favorite solo: Dave Weckl and Steve Gadd- title track to Weckl's cd "Master Plan". Both drummers playing on one track, alternating solos, panned slightly left and right. Not the best recording- completely overproduced, as are most of Dave's recordings, but great playing.
Anything by Vinnie Colaiuta...
NS
Novice build of a 9.2 system
I hope this is the right place to post, I'm an amateur woodworker but no experience of diy audio. I ordered 4 of the Dayton Audio BR-1 component kits and the components for a TriTrix MTM to act as a centre. I'll probably build a par of subs next year. I also plan to make stands for all the bookshelf speakers.
Progress will be slow as I am also renovating the room to be used as a home cinema, but I thought there might be some interest in the speaker build progress here.
Last night I managed to assemble three pairs of the crossovers. My soldering was acceptable after I found my iron that has been gathering dust for years. The hot glue work was messy but effective I think, as everything feels nice and secure.
Progress will be slow as I am also renovating the room to be used as a home cinema, but I thought there might be some interest in the speaker build progress here.
Last night I managed to assemble three pairs of the crossovers. My soldering was acceptable after I found my iron that has been gathering dust for years. The hot glue work was messy but effective I think, as everything feels nice and secure.
got 24 Telefunken E88CC... are they all good for the waste ?
Hello everyone,
I had the "opportunity" to get 24 Telefunken tubes, model E88CC. I'm pretty confident they are genuine, for reasons I won't mention here. I have a uTracer and tested all the tubes. I made two tests :
From what I read, is that I should get the typical Ia around 15mA at its minimum, mostly between 100 and 110%. However, most tubes are in the range 70-85% for Ia.
Below an example for one E88CC, and I would like you to comment it. The question is, are all these tubes good for the waste recycling ? Or do I oversee something and I'm sitting on a "small fortune" ?
I had the "opportunity" to get 24 Telefunken tubes, model E88CC. I'm pretty confident they are genuine, for reasons I won't mention here. I have a uTracer and tested all the tubes. I made two tests :
- quick check, where I set heater at 6.3V, Ua = 90V, Ug = -1.3V, and verified the Ia, which should be a typical 15mA.
- the curve tracing, where I'm able to measure the current in the two triodes at the same time, in function of Va and Vg. In fact the same as above but for multiple points.
From what I read, is that I should get the typical Ia around 15mA at its minimum, mostly between 100 and 110%. However, most tubes are in the range 70-85% for Ia.
Below an example for one E88CC, and I would like you to comment it. The question is, are all these tubes good for the waste recycling ? Or do I oversee something and I'm sitting on a "small fortune" ?
Code:
Telefunken E88CC
SECTION 1
Test conditions:
Va : 90 (V) Swing +/- 9 V (10%)
Vg : -1.3 (V) Swing +/- 0.13 V (10%)
Test results:
Ia : 11.41 (mA) 76 % of nominal 15 (mA)
Ra : 3.05 (kohm) 117 % of nominal 2.6 (kohm) Ra = dVa/dIa
Gm : 9.92 (mA/V) 79 % of nominal 12.5 (mA) Gm = dIa/dVg
mu : 30 (-) 92 % of nominal 33 (-) mu = Gm*Ra
SECTION 2
Test conditions:
Va : 90 (V) Swing +/- 9 V (10%)
Vg : -1.3 (V) Swing +/- 0.13 V (10%)
Test results:
Ia : 11.19 (mA) 75 % of nominal 15 (mA)
Ra : 3.15 (kohm) 121 % of nominal 2.6 (kohm) Ra = dVa/dIa
Gm : 10.5 (mA/V) 84 % of nominal 12.5 (mA/V) Gm = dIa/dVg
mu : 33 (-) 100 % of nominal 33 (-) mu = Gm*Ra