I pimped my Citation Sixteen! (or, resurrected?)
- By nattawa
- Solid State
- 5 Replies
Bought a beaten-up Harman Kardon Citation 16 as a fixer-up unit and thought I’d fix whatever went wrong and it’d be my sleeper amp, only to end up with gutting this legend out completely. Now this amp has nothing but chassis and heat-sinks that are left over from the Citation Sixteen. It has two-channel Leach amp in it, with an output stage consists of 5-pair/channel ThermalTrak devices, NJL3281/1032 of On-Semi. By the way, could this be the first Leach Amp on TermalTrak output devices in this forum? Any ways here go the pics:
ALL-BUCKLED-UP...will it be a rough ride?
LITTLE DRIVERS…Can they handle the ark?
HEAT-AND-ITS-SINK
I piggy-back bolted some extra aluminum--scrap extrusion yet not particularly cheap🙁 from ebay-- to the center channel of the original Citation 16 heat-sink where the TO3s used to be to hopefully beef-up the heat-sinking capacity.
PCBS
Got these fabricated in China , cheap and in better-than-okay quality
VAS
Voltage Amplification Stage assembled. I cut the GND copper foil to give the driver supply filter and the amplification stage supply filter separate ripple return paths after the PCB were made. The cuts show up on the component side as light marks mid way along the sides to the board edges
POWER-SUPPLY-BOARDS
These are hand-cut with a knife. The copper foils were later re-enforced with bus bars
PWR-CONNECTORS
Ring lugs over Erni Power-Tap was my choice of power connection
POWER CONNECTIONS
Each Power-Tap connector receives 2 ring lugs. For the center GND there are 7 wires, 3 of them form a triple #14 gauge going to the speaker binding post, the other4 are driver supply filter return, amplification stage supply filter return, output zobel GND lead, and the signal GND reference. For the power connections there are 3 wires per each rail, one goes to the amplification and driver stage, and #14 doubled go to the output transistor common rail. Why double/triple the wires you ask? The butt end of my ring lugs is too large for a #14 stranded, plus they all say size matters😉
BUS-BAR-BOT-COS
Current output board gets bus bars on the supply rails. I also put in pem nuts for easy attachment of the ring lugs. They were first pressed on the PCB into the plated holes, then got soldered to the copper foil.
BUS-BAR-TOP-COS
The output node gets a bus bar too
COS-BOT-WIRING
Ring lugs made doubled-up wiring easy
COS-DETAIL
Emitter resisters hooked up to the bus bar
COS-WIRING
Current output stage ready to go onto the transistor/heat-sink assembly. Oh, noticed the 2-conductor terminal block at about the lower left corner in the picture? They are temperature sensor terminals reserved for on-die temperature measurement or warning/protection. Four out of the 10 ThermalTrak diodes are hooked up in series and wired up to this terminal block.
MODULAR-AMP
This is how the thing looks
THE SHIELD
I sandwiched a third PCB of solid copper foil on GND in between the VAS and COS to cut down any possible capacitive couplings between the output stage and the input stage.
AMP-MODULE
Ready to go on the chassis and rock
AMP-OFF-CHASSIS
Powered up for the first time......with fingers crossed......
BIAS-ADJ
Started bias adjustment. I finally set the idle at 400mA to give the heat-sinks a nice warm touch. Stability has been good so far since the amp went into service a few months ago.
LEFT-CHNL-TOP
Left channel is on the chassis. The Neutrik RCA jacks look good, don’t they?
BINDING-POSTS
Are they too good?
R-CHNL-OFF-BINDPOSTS
Another view with right channel off chassis
TOP-VIEW
All put together! This is the "living room" of the chassis. The two black blocks sitting next to the RCA jacks are the speaker relays. These are automotive relays with 80A contact capacity. The transformer looks nice in the chassis to me, despite the fact it was scavenged from a broken Behringer EP2500 power amp.
spk-rly-RCA-jack
A close up view
BOT-VIEW
Let's go to the basement and take a look at all the supporting components. There are a few assemblies there, working on a secondary power supply. The secondary power supply transformer was scavenged from a broken CD player
INRUSH-LIMITING
This PCB has three relays of 12A AC contact capacity on board for the mains. One to connect through thermisters, the other two in parallel bypass the in-rush control when the rails have become stabilized. It also controls two out-board relays to cut in and out speakers. (more on this later). The coiled up twisted black/red wires in the middle (a bit unsightly) are not connected at this time. They are reserved for working with protection mechanisms to shutting down the power. The PCB in green behind the inrush board is a piece of scrap and work as a supporting base for other PCB assemblies to attach to.
DISCHARGR
It discharges all 4 power rails quickly when power is turned off. (more on this later) The black chunk in the lower right is the power switch with lighting. It came with 12V incandescent bulb in it, but I don’t like the yellowish color so I replaced the bulb with 4 white LEDs in series.
DC-DETECTION
It sends fault signals to the inrush PCB to have the speaker relay(s) cut out when DC is detected. It also lights up a warning LED indicating the channel in trouble.
IN-SVCE-TOP
Case closed.
IN-SVCE-REAR
Ain’t her rear end smokin’ hot? 😉
IN-SERVICE-Front
Hey, how do you like her in new shiny shoes? The original neon bulbs in the fixture have been replaced with LEDs that serve as DC warning. They seem to be glowing in the picture but they are in fact not. When they do they’d be much brighter than that.
My Paul-Sue-Barton’s are happy. So is the wifie. Beethoven has never sounded more Beethovenian.
TOE-OPERATED
The power switch is a push-button momentary switch so that one could easily operate with a toe and save his/her back. Here is how to:
http://www.flickr.com/photos/21102007@N04/4833640424/in/set-72157624460926929/
I’d get my dog to learn to do that for me if I had one.
About the Inrush PCB: (schematic will follow)
The big toroidal power transformer of over 1KVA and 80,000uF smoothing capacitance have made inrush current limiting a must. This circuit is based on hard-wired logic/timer devices, it controls the mains power relays and speaker relays. It works on a 12VDC secondary supply. This was laid out on a two-sided PCB that requires some basic SMT soldering skills to assemble. The circuit works with a lighted push-button switch with momentary contacts as the power switch, each push starts a 5-second time window during which the switch itself is disabled and the switch lamp flashes. When start from standby the soft-start relay will engage for as long as the time window lasts (5s), the mains power is applied through three GE CL-40 NTC thermister in series (15 ohms in total at room temperature). This will limit the inrush current and charge up the main caps in a controlled manner. The main caps should be charged up well within the 5-s time window and the rail voltage flats out. A flat-out detection circuit will engage a power-good monitor and if a power-good is positive the circuit enters power-on mode, the main relays (two in parallel) will bypass the inrush limiter and connect the primary winding of the power transform directly to the mains supply, the lamp in the power switch stops flashing to glow at a normal brightness, the speaker relays will also engage at the same moment given that there is no DC detected at the amplifiers’ output. The soft-start relay then cuts out at the end of the 5-s time window. If no power rail flat-out is detected or no power-good is detected during the 5-s time window, the main relays and the speaker relays will not engage, and the circuit returns to standby mode at the end of the time window, the lamp in the power switch then stops flashing to glow a dim light. Pushing the power switch during power-on mode will simply disengage power relays and speaker relays, and a 5-s time window follows to allow the main caps to be discharged deeply enough prior to responding next button push.
About the Discharger: (schematic will follow)
It brings main caps down to under 5V a few seconds of power off. It was built on prototyping board. The discharger is engaged whenever all the mains power relays cut out, and disengaged when any of the mains relays actuates. There are 4 jumpers on the board that allow for disabling the discharging operation. I used 4 photo couplers to isolate the control side from the audio GND, as well as audio GNDs of left and right channels. Such isolation also allows a very simple and uniform circuit implementation on all power rails using power MOFETs of one single model.
DC detecting circuit: (schematic will follow)
It works in tandem with the soft-start PCB to cut out speakers when DC presents at the amplifier output, it lights up a warning LED of the channel in trouble too. Built on prototyping board.
To be implemented: (schematic suggestion welcome)
An on-die temperature measurement/warning/protection using the roughed-in temperature sensor.
ALL-BUCKLED-UP...will it be a rough ride?
LITTLE DRIVERS…Can they handle the ark?
HEAT-AND-ITS-SINK
I piggy-back bolted some extra aluminum--scrap extrusion yet not particularly cheap🙁 from ebay-- to the center channel of the original Citation 16 heat-sink where the TO3s used to be to hopefully beef-up the heat-sinking capacity.
PCBS
Got these fabricated in China , cheap and in better-than-okay quality
VAS
Voltage Amplification Stage assembled. I cut the GND copper foil to give the driver supply filter and the amplification stage supply filter separate ripple return paths after the PCB were made. The cuts show up on the component side as light marks mid way along the sides to the board edges
POWER-SUPPLY-BOARDS
These are hand-cut with a knife. The copper foils were later re-enforced with bus bars
PWR-CONNECTORS
Ring lugs over Erni Power-Tap was my choice of power connection
POWER CONNECTIONS
Each Power-Tap connector receives 2 ring lugs. For the center GND there are 7 wires, 3 of them form a triple #14 gauge going to the speaker binding post, the other4 are driver supply filter return, amplification stage supply filter return, output zobel GND lead, and the signal GND reference. For the power connections there are 3 wires per each rail, one goes to the amplification and driver stage, and #14 doubled go to the output transistor common rail. Why double/triple the wires you ask? The butt end of my ring lugs is too large for a #14 stranded, plus they all say size matters😉
BUS-BAR-BOT-COS
Current output board gets bus bars on the supply rails. I also put in pem nuts for easy attachment of the ring lugs. They were first pressed on the PCB into the plated holes, then got soldered to the copper foil.
BUS-BAR-TOP-COS
The output node gets a bus bar too
COS-BOT-WIRING
Ring lugs made doubled-up wiring easy
COS-DETAIL
Emitter resisters hooked up to the bus bar
COS-WIRING
Current output stage ready to go onto the transistor/heat-sink assembly. Oh, noticed the 2-conductor terminal block at about the lower left corner in the picture? They are temperature sensor terminals reserved for on-die temperature measurement or warning/protection. Four out of the 10 ThermalTrak diodes are hooked up in series and wired up to this terminal block.
MODULAR-AMP
This is how the thing looks
THE SHIELD
I sandwiched a third PCB of solid copper foil on GND in between the VAS and COS to cut down any possible capacitive couplings between the output stage and the input stage.
AMP-MODULE
Ready to go on the chassis and rock
AMP-OFF-CHASSIS
Powered up for the first time......with fingers crossed......
BIAS-ADJ
Started bias adjustment. I finally set the idle at 400mA to give the heat-sinks a nice warm touch. Stability has been good so far since the amp went into service a few months ago.
LEFT-CHNL-TOP
Left channel is on the chassis. The Neutrik RCA jacks look good, don’t they?
BINDING-POSTS
Are they too good?
R-CHNL-OFF-BINDPOSTS
Another view with right channel off chassis
TOP-VIEW
All put together! This is the "living room" of the chassis. The two black blocks sitting next to the RCA jacks are the speaker relays. These are automotive relays with 80A contact capacity. The transformer looks nice in the chassis to me, despite the fact it was scavenged from a broken Behringer EP2500 power amp.
spk-rly-RCA-jack
A close up view
BOT-VIEW
Let's go to the basement and take a look at all the supporting components. There are a few assemblies there, working on a secondary power supply. The secondary power supply transformer was scavenged from a broken CD player
INRUSH-LIMITING
This PCB has three relays of 12A AC contact capacity on board for the mains. One to connect through thermisters, the other two in parallel bypass the in-rush control when the rails have become stabilized. It also controls two out-board relays to cut in and out speakers. (more on this later). The coiled up twisted black/red wires in the middle (a bit unsightly) are not connected at this time. They are reserved for working with protection mechanisms to shutting down the power. The PCB in green behind the inrush board is a piece of scrap and work as a supporting base for other PCB assemblies to attach to.
DISCHARGR
It discharges all 4 power rails quickly when power is turned off. (more on this later) The black chunk in the lower right is the power switch with lighting. It came with 12V incandescent bulb in it, but I don’t like the yellowish color so I replaced the bulb with 4 white LEDs in series.
DC-DETECTION
It sends fault signals to the inrush PCB to have the speaker relay(s) cut out when DC is detected. It also lights up a warning LED indicating the channel in trouble.
IN-SVCE-TOP
Case closed.
IN-SVCE-REAR
Ain’t her rear end smokin’ hot? 😉
IN-SERVICE-Front
Hey, how do you like her in new shiny shoes? The original neon bulbs in the fixture have been replaced with LEDs that serve as DC warning. They seem to be glowing in the picture but they are in fact not. When they do they’d be much brighter than that.
My Paul-Sue-Barton’s are happy. So is the wifie. Beethoven has never sounded more Beethovenian.
TOE-OPERATED
The power switch is a push-button momentary switch so that one could easily operate with a toe and save his/her back. Here is how to:
http://www.flickr.com/photos/21102007@N04/4833640424/in/set-72157624460926929/
I’d get my dog to learn to do that for me if I had one.
About the Inrush PCB: (schematic will follow)
The big toroidal power transformer of over 1KVA and 80,000uF smoothing capacitance have made inrush current limiting a must. This circuit is based on hard-wired logic/timer devices, it controls the mains power relays and speaker relays. It works on a 12VDC secondary supply. This was laid out on a two-sided PCB that requires some basic SMT soldering skills to assemble. The circuit works with a lighted push-button switch with momentary contacts as the power switch, each push starts a 5-second time window during which the switch itself is disabled and the switch lamp flashes. When start from standby the soft-start relay will engage for as long as the time window lasts (5s), the mains power is applied through three GE CL-40 NTC thermister in series (15 ohms in total at room temperature). This will limit the inrush current and charge up the main caps in a controlled manner. The main caps should be charged up well within the 5-s time window and the rail voltage flats out. A flat-out detection circuit will engage a power-good monitor and if a power-good is positive the circuit enters power-on mode, the main relays (two in parallel) will bypass the inrush limiter and connect the primary winding of the power transform directly to the mains supply, the lamp in the power switch stops flashing to glow at a normal brightness, the speaker relays will also engage at the same moment given that there is no DC detected at the amplifiers’ output. The soft-start relay then cuts out at the end of the 5-s time window. If no power rail flat-out is detected or no power-good is detected during the 5-s time window, the main relays and the speaker relays will not engage, and the circuit returns to standby mode at the end of the time window, the lamp in the power switch then stops flashing to glow a dim light. Pushing the power switch during power-on mode will simply disengage power relays and speaker relays, and a 5-s time window follows to allow the main caps to be discharged deeply enough prior to responding next button push.
About the Discharger: (schematic will follow)
It brings main caps down to under 5V a few seconds of power off. It was built on prototyping board. The discharger is engaged whenever all the mains power relays cut out, and disengaged when any of the mains relays actuates. There are 4 jumpers on the board that allow for disabling the discharging operation. I used 4 photo couplers to isolate the control side from the audio GND, as well as audio GNDs of left and right channels. Such isolation also allows a very simple and uniform circuit implementation on all power rails using power MOFETs of one single model.
DC detecting circuit: (schematic will follow)
It works in tandem with the soft-start PCB to cut out speakers when DC presents at the amplifier output, it lights up a warning LED of the channel in trouble too. Built on prototyping board.
To be implemented: (schematic suggestion welcome)
An on-die temperature measurement/warning/protection using the roughed-in temperature sensor.
Hand wound transformer question
Hey guys, i'm preparing to build a ribbon microphone and i've decided on winding my own transformer.
I've done the math and come up with the appropriate wire gauges and turn counts, and i will be using a smallish iron powder toroidal core, but i was wondering if anyone potentially has more knowledge when it comes to audio transformer construction. My biggest question currently has to do with the "layout" of the windings, more specifically, should the primary and secondary windings be wound into each other, or separated along the circumference of the toroid? i'll attach an iffy paint drawing to illustrate what i mean if it's unclear 🙂
(also another thing, but does the orientation of the windings in relation to each other, i.e. if one's would Clockwise and the other counter-clockwise?)
I've done the math and come up with the appropriate wire gauges and turn counts, and i will be using a smallish iron powder toroidal core, but i was wondering if anyone potentially has more knowledge when it comes to audio transformer construction. My biggest question currently has to do with the "layout" of the windings, more specifically, should the primary and secondary windings be wound into each other, or separated along the circumference of the toroid? i'll attach an iffy paint drawing to illustrate what i mean if it's unclear 🙂
(also another thing, but does the orientation of the windings in relation to each other, i.e. if one's would Clockwise and the other counter-clockwise?)
LM1875 Early Clipping
- By DylanBenton
- Chip Amps
- 11 Replies
Good Evening,
I have a LM1875 running single supply on a 24V SMPS which seems to be hitting the rails and clipping at about 17v (peak to peak) using a 400hz sine wave.
The chip is receiving 21.4v after regulation (LM317t) and while under load. How close can you get to the rails before distortion is expected?
Even with it biased at 10v, i thought it should get 20v without clipping. Is there anything i could be missing to cause this?
I would also assume that getting an output of 6v RMS on a 8ohm load would be pulling roughly 750ma, but it seems to be much lower.
Any help would be gratefully appreciated 🙂
I have a LM1875 running single supply on a 24V SMPS which seems to be hitting the rails and clipping at about 17v (peak to peak) using a 400hz sine wave.
The chip is receiving 21.4v after regulation (LM317t) and while under load. How close can you get to the rails before distortion is expected?
Even with it biased at 10v, i thought it should get 20v without clipping. Is there anything i could be missing to cause this?
I would also assume that getting an output of 6v RMS on a 8ohm load would be pulling roughly 750ma, but it seems to be much lower.
Any help would be gratefully appreciated 🙂
Pcb layout doubt
- By madhukannan
- Solid State
- 7 Replies
While making a PCB layout should we keep signal, Zobel, and decoupling caps grounds completely isolated? and run separate wires to the power supply ground T ? or is it required to have a connection between them in the PCB?
To which ground the constant current source ground can be combined?
To which ground the constant current source ground can be combined?
6П15П-ЕВ / 6P15P-EV = EL803S / SV83 NOS, NIB (lot of 100pcs)
- By OAA7
- Vendor's Bazaar
- 6 Replies
FS: 6П15П-ЕВ / 6P15P-EV = EL803S / SV83 NOS, NIB (lot of 100pcs)
Hi,
I have in stock excellent special quality electron tubes 6П15П-ЕВ / 6P15P-EV
= EL803S / EL83 / SV83
Index -EB means:
B = tubes of increased mechanical strength and reliability
E = tubes of increased durability (5000 hours or more)
Saratov factory "Reflector"
all the same date codes = Dec. 1976
minimum order = 100 pcs (one box)
price = $200 (i.e. $2 for 1piece)
shipping cost (2500 g)= $30 by airmail
Best regards!
-------------------
Olexandr
Kharkiv, UKRAINE
skype: OAA-1974
Hi,
I have in stock excellent special quality electron tubes 6П15П-ЕВ / 6P15P-EV
= EL803S / EL83 / SV83
Index -EB means:
B = tubes of increased mechanical strength and reliability
E = tubes of increased durability (5000 hours or more)
Saratov factory "Reflector"
all the same date codes = Dec. 1976
minimum order = 100 pcs (one box)
price = $200 (i.e. $2 for 1piece)
shipping cost (2500 g)= $30 by airmail
Best regards!
-------------------
Olexandr
Kharkiv, UKRAINE
skype: OAA-1974
Lowest safe loadline: what is the limit?
- By zintolo
- Tubes / Valves
- 135 Replies
I'm designing a amp to see the limits of a new feedback system, and I would like to know what is the limit you consider on the lowest side for the loadline.
Please consider that the DF has not to be considered here.
The amp is a PP based on a pair of EL34 at 450V B+.
Initial OPT was 6k6 with UL 23%, now I would like to test a 4k with UL 23% I have, but I would avoid to blow a pair of EL34.
The point is that the loadline is on the edge of 2x the max plate dissipation on some points (as highlighted on the image) and this considering a load of 8 Ohm, so it's even worst at mid frequencies where load is usually lower.
What is the limit you consider when you design an amp?
Is that loadline the lowest you'd use, not considering the DF in the equation?
Thank you in advance,
Roberto
Please consider that the DF has not to be considered here.
The amp is a PP based on a pair of EL34 at 450V B+.
Initial OPT was 6k6 with UL 23%, now I would like to test a 4k with UL 23% I have, but I would avoid to blow a pair of EL34.
The point is that the loadline is on the edge of 2x the max plate dissipation on some points (as highlighted on the image) and this considering a load of 8 Ohm, so it's even worst at mid frequencies where load is usually lower.
What is the limit you consider when you design an amp?
Is that loadline the lowest you'd use, not considering the DF in the equation?
Thank you in advance,
Roberto
Attachments
Microphone Isolation Panel instead of Rear Absorbtion Pads
- By Bradstone
- Room Acoustics & Mods
- 0 Replies
Attachments
Harmony H205/Silvertone 1342 OT
- By eetechTom
- Instruments and Amps
- 17 Replies
Starting my first classic amp restoration and have an output transformer question.The Harmony H205 amp I bought, had the OT replaced with a 16 ohm output sub. It’s a 6V6 pp circuit, rated at 12W I believe?. Haven’t gotten to the point of powering it up yet, but will obviously need a better OT. That orange cap needs to go too
This amp has the original Rola 12”, 3.2 ohm speaker. Any suggestions on a quality OT would be greatly appreciated. Want to do justice to this classic.
This amp has the original Rola 12”, 3.2 ohm speaker. Any suggestions on a quality OT would be greatly appreciated. Want to do justice to this classic.
Attachments
Guesstimating transformer power ratings
- By Kay Pirinha
- Power Supplies
- 12 Replies
Hi,
in the past two years I've harvested a bunch of power transformers from some cheesiy sounding and crappy Hammond transistor organs. Sadly, I didn't have a close look at their badges and the power consumption that might have been written there, but anyway, all these organs featured Leslie or Rotosonic units whose motors are of unknown power consumption as well.
The 1st pic shows a pair of identical trannies, Hammond part # 003-054471, coming from a Collonnade and a - smaller - Aurora Classic. Their lamination stacks measure 105 x 87 x 55 mm (4 1/8 x 3½ x 2 1/4 "):
Next one is the tranny of a notably bigger Concorde. Part # 003-046819. Lamination outline is the same, but stack height is a bit lower: 105 x 87 x 50 mm (4 1/8 x 3½ x 2 "):
Next one came form a Model 8022 organ. Part # 003-048011. Laminations measure 95 x 80 x 50 mm (3 3/4 x 3 1/8 x 2 "):
The next pair also was in the Colonnade and Aurora organs. Their primaries are 115 Vac, secondary is 14 Vac. Perhaps they might serve in a BTL pair (2 x 2) of amplifiers. Part # 003-054853, laminations are 76 x 63 x 41 mm (3 x 2 1/2 x 1 5/8 "):
The smallest one. Part # 003-046374, laminations are 66 x 56 x 26 mm (2 5/8 x 2 3/16 x 1 "):
Finally a 117 Vac power tranny that came from a Leslie 121 multi channel amplifier. It powered four almost identical amplifiers, consisting of a 12AU7 and a pair of fix biased 7189's each. This is the one I was referring to in my proper winding technique thread. I'm planning to rewind it as an OT of about 40 W power. Laminations are 114 x 95 x 33 mm (4½ x 3 3/4 x 1 1/4 "):
Which power capabilities can I expect from these transformers?
Best regards!
in the past two years I've harvested a bunch of power transformers from some cheesiy sounding and crappy Hammond transistor organs. Sadly, I didn't have a close look at their badges and the power consumption that might have been written there, but anyway, all these organs featured Leslie or Rotosonic units whose motors are of unknown power consumption as well.
The 1st pic shows a pair of identical trannies, Hammond part # 003-054471, coming from a Collonnade and a - smaller - Aurora Classic. Their lamination stacks measure 105 x 87 x 55 mm (4 1/8 x 3½ x 2 1/4 "):
Next one is the tranny of a notably bigger Concorde. Part # 003-046819. Lamination outline is the same, but stack height is a bit lower: 105 x 87 x 50 mm (4 1/8 x 3½ x 2 "):
Next one came form a Model 8022 organ. Part # 003-048011. Laminations measure 95 x 80 x 50 mm (3 3/4 x 3 1/8 x 2 "):
The next pair also was in the Colonnade and Aurora organs. Their primaries are 115 Vac, secondary is 14 Vac. Perhaps they might serve in a BTL pair (2 x 2) of amplifiers. Part # 003-054853, laminations are 76 x 63 x 41 mm (3 x 2 1/2 x 1 5/8 "):
The smallest one. Part # 003-046374, laminations are 66 x 56 x 26 mm (2 5/8 x 2 3/16 x 1 "):
Finally a 117 Vac power tranny that came from a Leslie 121 multi channel amplifier. It powered four almost identical amplifiers, consisting of a 12AU7 and a pair of fix biased 7189's each. This is the one I was referring to in my proper winding technique thread. I'm planning to rewind it as an OT of about 40 W power. Laminations are 114 x 95 x 33 mm (4½ x 3 3/4 x 1 1/4 "):
Which power capabilities can I expect from these transformers?
Best regards!
Goldentone single valve guitar amp troubleshoot
- By Yellow Cab
- Instruments and Amps
- 40 Replies
Attachments
-
Locked
High End pseudoscience. Electronics and enclosure marketing vs speaker efficiency
- By afk
- Everything Else
- 34 Replies
High end, High fidelity or Audiophile terms are just product of misinformation wars, that were created in the WW2 to manipulate reality and build national sentiment and morale to recruit soldiers and win wars, and this has expanded from politics to create an eternal voting ping-pong and to advertising creating an eternal consumer toddler. An the audio consumer segment is probably one of the most filled with pseudoscience and misleading, without showing real data of the products.
We watch attractive adverts with speaker cabinets and electronics with good picture presentation and supposed great technology, we want to own them like retards, me included today as I can fall for it so easily.
So let's talk about real facts about sound science and the most critical factor in sound transmission is efficiency and this is a problem with speakers because no matter how good the audio format, bitrate, bit depth, DAC, amplifier, speaker cone, enclosure is, we burn 99% of the sound and the speaker transforms only 1% from energy to sound, lets say with a 8ohm speaker at 92db sensibility, and this is what matters most.
So with a 3db increase at 95db we have a 2% efficient speaker and if we increase the sensibility to 131db that speaker is 13% and we can play the sound low and hear most of the sound details with an mp3, flac, DVD-A or DTS-MA.
The ways to accomplish speaker efficiency is with speaker sensibility and area, Xmax, horns and enclosure type and volume while electronic efficiency is made with gain structure and also by removing passive crossovers and using class D,T, etc amps with 90-100% efficiency. However the most noticeable methods for speaker db increase are horns and gain structure.
In my case i use gain structure with Foobar at minimum while windows preamp and amp at maximum, reducing amp volume and raising foobar to reduce noise at low volume, however i can use any small speaker very loud without cone excursion or play loud a big subwoofer with a 25w class-D amp board
By reducing the source volume I am supposed to eat bit rate and bit depth, but the music gains richness so when i use a common setup with amp+speaker with amp at low volume it sounds poor whatever the "quality" of the components.
The main drawback of this gain structure is that i can blow the speaker if i raise the foobar volume or windows play any sound suddenly. There's a notable difference by using DVD-A instead flac in Foobar and i can raise the volume and the richness of the sound and low distortion its quite noticeable, the same with dts-ma.
We watch attractive adverts with speaker cabinets and electronics with good picture presentation and supposed great technology, we want to own them like retards, me included today as I can fall for it so easily.
So let's talk about real facts about sound science and the most critical factor in sound transmission is efficiency and this is a problem with speakers because no matter how good the audio format, bitrate, bit depth, DAC, amplifier, speaker cone, enclosure is, we burn 99% of the sound and the speaker transforms only 1% from energy to sound, lets say with a 8ohm speaker at 92db sensibility, and this is what matters most.
So with a 3db increase at 95db we have a 2% efficient speaker and if we increase the sensibility to 131db that speaker is 13% and we can play the sound low and hear most of the sound details with an mp3, flac, DVD-A or DTS-MA.
The ways to accomplish speaker efficiency is with speaker sensibility and area, Xmax, horns and enclosure type and volume while electronic efficiency is made with gain structure and also by removing passive crossovers and using class D,T, etc amps with 90-100% efficiency. However the most noticeable methods for speaker db increase are horns and gain structure.
In my case i use gain structure with Foobar at minimum while windows preamp and amp at maximum, reducing amp volume and raising foobar to reduce noise at low volume, however i can use any small speaker very loud without cone excursion or play loud a big subwoofer with a 25w class-D amp board
By reducing the source volume I am supposed to eat bit rate and bit depth, but the music gains richness so when i use a common setup with amp+speaker with amp at low volume it sounds poor whatever the "quality" of the components.
The main drawback of this gain structure is that i can blow the speaker if i raise the foobar volume or windows play any sound suddenly. There's a notable difference by using DVD-A instead flac in Foobar and i can raise the volume and the richness of the sound and low distortion its quite noticeable, the same with dts-ma.
Simple DIYable Waveguide testing (dome tweeters)
Hi All,
I have been doing some testing with shallow waveguides for my BaSSlines project that I thought you all might be interested in. I posted this in my BaSSlines thread, but realized many of you who might be interested could miss it there. I created an insert into the baffle that would allow me to make multiple WG's and insert them into the same baffle (see photo below), with same tweeter, same mic setup, position, etc. The tweeter is the Peerless HDS with the face plate removed. The tweeter is mounted by pressing it to the back of he WG cutout, held by a woof fixture. The measurements were all taken at 1 meter, with the mic 80" high, in the center of a room with vaulted ceilings probably 15' high at that point and with a 4ms gated window.
All the WG's were created from mdf by boring a hole with a forstner bit, then rounding over the appropraite amount and then routing from the back for the palnned depth of either 1/2" deep or 3/4" deep in these cases. These are something just about any DIYer can build petty easily, which was the idea. There are a few tricks to doing this, most notably, when using a 3/4" rounvoer bit, you have to have a backer piece to you mdf baffle that you also bore a hole through. This backer piece is needed for the bearing of the deeper 3/4" roundover bit to ride on. All the bore through holes on these were adjusted so the final throat sizes are about 1-1/4" +- 1/32" at the final size.
Most of the plots show the waveguide perfomance at 0-15-30-45 and 60º of axis horizontally, so you can see the effect on axis and the directivity off axis. The first plot is the HDS with a standard flush mount. My goal with the waveguide is to get some boost at the low end so that when qualized out in the crossover you get the possible benefits of lowered distortion, slighly higher sensitivity, better off axis directivity and a counter to the typical rising responce of the HDS tweeter on axis, which might be fatiguing to some over time. Also included are some comparisons of the favorite WG results on axis with each other.
I'll include some photos of the waveguide testing insert setup in this post and in the next one I'll post the results.
I have been doing some testing with shallow waveguides for my BaSSlines project that I thought you all might be interested in. I posted this in my BaSSlines thread, but realized many of you who might be interested could miss it there. I created an insert into the baffle that would allow me to make multiple WG's and insert them into the same baffle (see photo below), with same tweeter, same mic setup, position, etc. The tweeter is the Peerless HDS with the face plate removed. The tweeter is mounted by pressing it to the back of he WG cutout, held by a woof fixture. The measurements were all taken at 1 meter, with the mic 80" high, in the center of a room with vaulted ceilings probably 15' high at that point and with a 4ms gated window.
All the WG's were created from mdf by boring a hole with a forstner bit, then rounding over the appropraite amount and then routing from the back for the palnned depth of either 1/2" deep or 3/4" deep in these cases. These are something just about any DIYer can build petty easily, which was the idea. There are a few tricks to doing this, most notably, when using a 3/4" rounvoer bit, you have to have a backer piece to you mdf baffle that you also bore a hole through. This backer piece is needed for the bearing of the deeper 3/4" roundover bit to ride on. All the bore through holes on these were adjusted so the final throat sizes are about 1-1/4" +- 1/32" at the final size.
Most of the plots show the waveguide perfomance at 0-15-30-45 and 60º of axis horizontally, so you can see the effect on axis and the directivity off axis. The first plot is the HDS with a standard flush mount. My goal with the waveguide is to get some boost at the low end so that when qualized out in the crossover you get the possible benefits of lowered distortion, slighly higher sensitivity, better off axis directivity and a counter to the typical rising responce of the HDS tweeter on axis, which might be fatiguing to some over time. Also included are some comparisons of the favorite WG results on axis with each other.
I'll include some photos of the waveguide testing insert setup in this post and in the next one I'll post the results.
Cheap eBay subwoofer amps
- By drumcircle
- Subwoofers
- 1 Replies
There are some cheap, cheap $40 car subwoofer amps suggesting around 1,000w or more. I bought one (PA-80D) to pair with a decades old but very capable DELL 1,100w PSU from a server -- something you can find for $20 from one of many server liquidators. I received the amp and found 8 switching devices, emailed the seller, and was told that it uses the Toshiba 5198 1941 chipset and does around 300w RMS. It seems like a well-built unit and for $60 all-in, decent value for 300w RMS. I'm still looking for a budget 1-2kw solution...
Attachments
Interesting "archeological" find
- By Elvee
- Solid State
- 18 Replies
I am in the process of sorting out my "hardware archives".
In doing so, I stumbled upon a very unimpressive prototype, dating back from the pre-2000, pre-sim years:
One shouldn't judge it based on its shaggy looks though: I tested it, and it performs surprising well.
Like most of my amplifiers, it has some kind of auto-bias circuit.
Very often, the auto-bias introduces unwanted artifacts, especially in the crossover region.
To evaluate the quality, I tested it under low voltage amplitude, high current, high frequency conditions with a 50kHz triangle wave and a 2 ohm load:
The result is pretty immaculate!
The quiescent current for the total amplifier is ~200mA.
The circuit is stable, clean and tolerant and could serve as a starting base for a real amplifier.
Even better, I managed to reconcile the physical circuit with my paper archives (an outstanding feat!):
The circuit is not ultra-simple, but it isn't ultra complicated either.
In doing so, I stumbled upon a very unimpressive prototype, dating back from the pre-2000, pre-sim years:
One shouldn't judge it based on its shaggy looks though: I tested it, and it performs surprising well.
Like most of my amplifiers, it has some kind of auto-bias circuit.
Very often, the auto-bias introduces unwanted artifacts, especially in the crossover region.
To evaluate the quality, I tested it under low voltage amplitude, high current, high frequency conditions with a 50kHz triangle wave and a 2 ohm load:
The result is pretty immaculate!
The quiescent current for the total amplifier is ~200mA.
The circuit is stable, clean and tolerant and could serve as a starting base for a real amplifier.
Even better, I managed to reconcile the physical circuit with my paper archives (an outstanding feat!):
The circuit is not ultra-simple, but it isn't ultra complicated either.
Replace Tascam 122MK2 deck's VFD by LED
- By eaglebear
- Analogue Source
- 1 Replies
My display unit is already aging but the CPU is OK,so I decided to replace it with LED.The segments of this VFD are drived in DC -12V to +12V,I use some transistor to amplify current and convert Polarity for 4 byte Common cathode LED module，here are some pics.
SCH and PCB
The final DIY
SCH and PCB
The final DIY
Power supply theory?
- By stagekraft
- Power Supplies
- 14 Replies
Hey All,
Put on your "Double E" thinking cap and give me your opinion on this.
Now I was weened on audio electronics in the late 70's, and for the past 40 years or so I've designed, built and repaired a lot of stuff, but I just ran upon something that baffles me.
A guy brought me a powered sub-woofer to fix, and there's something about the power supply that I don't get.
Look at this schematic, the transformer has two secondary's, the top one is a single ended higher voltage that feeds the power amp, (which is also a strange design).
But look at the bottom secondary, a lower voltage "center tapped" winding that feeds two typical bipolar zener supplies off the same bridge rectifier, each one supplies a few opamps (I guess the designer thought it was more cost effective to double the parts count rather than using bigger parts, like a 1N4744 which has twice the current of the 1N5245, and 1/4W 330 ohm resisters instead if 1/8W).
But look at the center tap, it is fused to the chassis ground (what?).....
So if some over-current event happens and blows the fuse,
IF all the components are still good, but the supply's no longer reference to the center tap,
THEN in theory, does this become a "dual voltage" supply instead of "bipolar"?
That is, does the negative rail become 0V, and the chassis ground become +15V, and the positive rail become +30V?
OR IF a zener on the negative rail is shorted, THEN the negative rail become 0V, the chassis ground becomes 0V (due to the shorted zener), and the positive rail becomes +15V?
OR IF a zener on the positive rail is shorted, THEN the negative rail becomes 0V, the chassis ground becomes +15V, and the positive rail is also +15V (due to the shorted zener)?
Am I missing some obvious "good design practice" here, or does this look as goofy to ya'll as it does to me?
JohnR
Put on your "Double E" thinking cap and give me your opinion on this.
Now I was weened on audio electronics in the late 70's, and for the past 40 years or so I've designed, built and repaired a lot of stuff, but I just ran upon something that baffles me.
A guy brought me a powered sub-woofer to fix, and there's something about the power supply that I don't get.
Look at this schematic, the transformer has two secondary's, the top one is a single ended higher voltage that feeds the power amp, (which is also a strange design).
But look at the bottom secondary, a lower voltage "center tapped" winding that feeds two typical bipolar zener supplies off the same bridge rectifier, each one supplies a few opamps (I guess the designer thought it was more cost effective to double the parts count rather than using bigger parts, like a 1N4744 which has twice the current of the 1N5245, and 1/4W 330 ohm resisters instead if 1/8W).
But look at the center tap, it is fused to the chassis ground (what?).....
So if some over-current event happens and blows the fuse,
IF all the components are still good, but the supply's no longer reference to the center tap,
THEN in theory, does this become a "dual voltage" supply instead of "bipolar"?
That is, does the negative rail become 0V, and the chassis ground become +15V, and the positive rail become +30V?
OR IF a zener on the negative rail is shorted, THEN the negative rail become 0V, the chassis ground becomes 0V (due to the shorted zener), and the positive rail becomes +15V?
OR IF a zener on the positive rail is shorted, THEN the negative rail becomes 0V, the chassis ground becomes +15V, and the positive rail is also +15V (due to the shorted zener)?
Am I missing some obvious "good design practice" here, or does this look as goofy to ya'll as it does to me?
JohnR
My best upgrade ever!
It's a fact that few of us can make cabinets to the cosmetic standards of the major manufacturers. And back in the day when Sony wanted to be 'high-end' they made some high-end speaker cabinets. But the designs of these cabinets made them very retro very quick.
Over the years I have tried many alternatives but the bookshelf speakers that come with the Sony SS-CPX1 are my preferred fronts, the deep cabinets and Kevlar drivers representing the sound I like. The problem is that in 2022 they so effing butt ugly that divorce lawyers salivate at the thought of me keeping them in house.
I bought a pair of Wharfedale Diamonds but they weren't 'it'.
The solution cost $3 and 2 hours.
Seriously I didn't think $2 of spray paint and dab of sugar soap would change my life. Trust me, at home, I now get lucky - a lot.
Over the years I have tried many alternatives but the bookshelf speakers that come with the Sony SS-CPX1 are my preferred fronts, the deep cabinets and Kevlar drivers representing the sound I like. The problem is that in 2022 they so effing butt ugly that divorce lawyers salivate at the thought of me keeping them in house.
I bought a pair of Wharfedale Diamonds but they weren't 'it'.
The solution cost $3 and 2 hours.
Seriously I didn't think $2 of spray paint and dab of sugar soap would change my life. Trust me, at home, I now get lucky - a lot.
Attachments
RTA Question using REW
In the spectrum, which indicates positive or negative phase for say, H2? Does the polarity of the harmonics change sign?
Thank you!
Thank you!
FH9VX pcbs
Available 6 (stereo) pcbs of the Prasi/XRK FH9VX amplifier board.
£3 each posted UK
£6 Europe and most of ROW
£3 each posted UK
£6 Europe and most of ROW
For Sale Transformers for tube projects, Hammond, Edcor
- By itsikhefez
- Swap Meet
- 1 Replies
