Latest Custom Preamp
Hello,
My latest preamp/switcher project and build. This pre offers all the normal functions you'd expect in a pre, along with a couple selectable features. The design and layout of the board was done by fellow DIY'er, jhofland. It is based on the excellent OPA1656 chip, and other support ICs along with a few TH parts, and external breakout boards for volume, selector and headphone. The PCB is double sided and turned out beautifully. It has a fully, self-contained and integrated PSU. No power brick required.
This project had it's roots in my desire to have a matching preamp, to mate with a recently completed Modulus- 86 amp build.
Latest Preamp and Modulus-86 amp.
As mentioned before, the guts of the pre is a double-sided preamp PCB. The design specs feature;
o - Based on TI's OAP1656 opamp chip.
o - Uses TI's OAP1637 fully differential chip.
o - Uses Analog Devices' MAX79220 headphone amplifier.
o - 1 balanced input
o - 3 single ended inputs
o - 1 balanced output
o - 1 singled ended output
o - 1 separate headphone amp
o - 1 subwoofer output w/selectable crossover at, 80, 120, or 200Hz
o - 1 12V Trigger out jack (3.5mm)
o - adjustable gain at 0dB, 6dB, or 12dB (onboard 4-pin DIP)
Other features include;
o - Use of small breakout boards for the;
(1) the volume control pot
(2) the input selector with LED KK connectors
(3) Headphone output jack
Micro-match connectors are used for connection from the main board to the above remote breakout PCBs.
o - All I/O is also available with the use of MolexKK 2 and 3 pin PCB headers.
o - All onboard and integrated PSUs. No power brick to contend with.
o - Integrated IEC connector on read panel.
Top/Bottom view of the PCBs;
Here is what the fully populated board looks like, sans the 5V power module.
The objective of this particular project was to build a general purpose preamp with the features I wanted, and more specifically be a matching 'mate' to my Modulus-86 amp. This, of course, would involve using an identical mini-ITX as pictured above. I like to experiment with new and different enclosures that aren't run of the mill silver and black traditional audio cases. Because of this factor, you're never sure if you'll be successful in getting everything installed in the same sized case. Hence the custom preamp PCB. The PCB is 140mm x 140mm. This doesn't leave any room leftover for other pieces you may need. I had a pretty good idea of what I was dealing with and other remote software module I was planning on using in the build. The PCB turned out great as fabbed by JLCPCB, and fits perfectly in my red case. This mini-ITX HTPC is available online here at Amazon.
Using this type of unconventional enclosure general will require more than just drilling holes. There is a degree of case work that's required in the way of front and/or back panels. I have a 3D printer that works well for creating custom sized panels needed for converting a computer case to a useful piece of audio gear. And, you have to be prepared to modify your design as you go along. 🙂 This is a very challenging and time consuming process. And if you're a perfectionist well.....you know how it goes.
When considering the features I wanted in the preamp, I wanted to make it as flexible as possible, so that it could be used in various types of situations and enclosures. One of those features is the use of either; (1) RCA jacks that can be soldered directly onto the PCB, or (2) use 3-pin MolexKK headers on the PCB. The former would involve easier case work, as you could simply cut out a rectangle on the back panel and expose all of the pre's I/O more easily, while the latter could be used with casework that already has holes for the I/O. These are simple alternatives depending upon your preference and implementation. This feature is not available for the balanced connectors.
Here's an image of the various I/O connectors and footprint for the RCA jacks.
Another feature I like to have, and is on all late model PC cases - for about the past 20yrs - is the momentary on/off switch on the front or top of cases. To take advantage of such a switch you need some sort of low-voltage switch to trigger the mains, or simply act as an inline switch to a PSU. In past projects, I've used a small softstart switch (also designed by jhofland), that is ideal for a MO switch to turn on new builds. It provides for using a single switch, and even the Power and HDD LEDs also on the front panel of mini-ITX cases. I use these in almost all my projects over the past couple of years.
Remote low-voltage softswitch.
Also designed into this preamp are the breakout boards for the 3 operational features like; (1) Input selector, (2) volume control, and (3) headphone jack. Putting them on breakout PCBs allow for different mounting/placement options. The Micromatch (TE Connectivity) connectors and cables are used to connect them to the main preamp board.
Here are a few images of my build in process.
Final layout of the Back Panel. (4MM thick 3D printed)
Fully wired up preamp.
Fully finished and closed up preamp with smoked glass top.
The dynamic duo. 🙂
Temporary living room testing setup with vintage, HP-100 4-way speakers. The combo sounds so awesome, and the dynamics are really something you've got to hear.
If interested in the PCB board for this preamp and/or the low-voltage softstart board PM me for details.
Enjoy,
Rick
My latest preamp/switcher project and build. This pre offers all the normal functions you'd expect in a pre, along with a couple selectable features. The design and layout of the board was done by fellow DIY'er, jhofland. It is based on the excellent OPA1656 chip, and other support ICs along with a few TH parts, and external breakout boards for volume, selector and headphone. The PCB is double sided and turned out beautifully. It has a fully, self-contained and integrated PSU. No power brick required.
This project had it's roots in my desire to have a matching preamp, to mate with a recently completed Modulus- 86 amp build.
Latest Preamp and Modulus-86 amp.
As mentioned before, the guts of the pre is a double-sided preamp PCB. The design specs feature;
o - Based on TI's OAP1656 opamp chip.
o - Uses TI's OAP1637 fully differential chip.
o - Uses Analog Devices' MAX79220 headphone amplifier.
o - 1 balanced input
o - 3 single ended inputs
o - 1 balanced output
o - 1 singled ended output
o - 1 separate headphone amp
o - 1 subwoofer output w/selectable crossover at, 80, 120, or 200Hz
o - 1 12V Trigger out jack (3.5mm)
o - adjustable gain at 0dB, 6dB, or 12dB (onboard 4-pin DIP)
Other features include;
o - Use of small breakout boards for the;
(1) the volume control pot
(2) the input selector with LED KK connectors
(3) Headphone output jack
Micro-match connectors are used for connection from the main board to the above remote breakout PCBs.
o - All I/O is also available with the use of MolexKK 2 and 3 pin PCB headers.
o - All onboard and integrated PSUs. No power brick to contend with.
o - Integrated IEC connector on read panel.
Top/Bottom view of the PCBs;
Here is what the fully populated board looks like, sans the 5V power module.
The objective of this particular project was to build a general purpose preamp with the features I wanted, and more specifically be a matching 'mate' to my Modulus-86 amp. This, of course, would involve using an identical mini-ITX as pictured above. I like to experiment with new and different enclosures that aren't run of the mill silver and black traditional audio cases. Because of this factor, you're never sure if you'll be successful in getting everything installed in the same sized case. Hence the custom preamp PCB. The PCB is 140mm x 140mm. This doesn't leave any room leftover for other pieces you may need. I had a pretty good idea of what I was dealing with and other remote software module I was planning on using in the build. The PCB turned out great as fabbed by JLCPCB, and fits perfectly in my red case. This mini-ITX HTPC is available online here at Amazon.
Using this type of unconventional enclosure general will require more than just drilling holes. There is a degree of case work that's required in the way of front and/or back panels. I have a 3D printer that works well for creating custom sized panels needed for converting a computer case to a useful piece of audio gear. And, you have to be prepared to modify your design as you go along. 🙂 This is a very challenging and time consuming process. And if you're a perfectionist well.....you know how it goes.
When considering the features I wanted in the preamp, I wanted to make it as flexible as possible, so that it could be used in various types of situations and enclosures. One of those features is the use of either; (1) RCA jacks that can be soldered directly onto the PCB, or (2) use 3-pin MolexKK headers on the PCB. The former would involve easier case work, as you could simply cut out a rectangle on the back panel and expose all of the pre's I/O more easily, while the latter could be used with casework that already has holes for the I/O. These are simple alternatives depending upon your preference and implementation. This feature is not available for the balanced connectors.
Here's an image of the various I/O connectors and footprint for the RCA jacks.
Another feature I like to have, and is on all late model PC cases - for about the past 20yrs - is the momentary on/off switch on the front or top of cases. To take advantage of such a switch you need some sort of low-voltage switch to trigger the mains, or simply act as an inline switch to a PSU. In past projects, I've used a small softstart switch (also designed by jhofland), that is ideal for a MO switch to turn on new builds. It provides for using a single switch, and even the Power and HDD LEDs also on the front panel of mini-ITX cases. I use these in almost all my projects over the past couple of years.
Remote low-voltage softswitch.
Also designed into this preamp are the breakout boards for the 3 operational features like; (1) Input selector, (2) volume control, and (3) headphone jack. Putting them on breakout PCBs allow for different mounting/placement options. The Micromatch (TE Connectivity) connectors and cables are used to connect them to the main preamp board.
Here are a few images of my build in process.
Final layout of the Back Panel. (4MM thick 3D printed)
Fully wired up preamp.
Fully finished and closed up preamp with smoked glass top.
The dynamic duo. 🙂
Temporary living room testing setup with vintage, HP-100 4-way speakers. The combo sounds so awesome, and the dynamics are really something you've got to hear.
If interested in the PCB board for this preamp and/or the low-voltage softstart board PM me for details.
Enjoy,
Rick
Hifi car audio guy taking his addiction inside
- By RickWilson
- Introductions
- 4 Replies
Hey all - excited to learn a bit more from this community.
Currently a massive DIY car audio guy with a pretty competitive nationally ranked vehicle filled with Accuton Automotive, Focal Utopia, Brax, Mosconi and other nice SQ brands. Love the DIY side.
My truck's front stage:
Amp rack I built:
On to the home audio side:
Been looking to create myself a basic, but quality reference 2.0 or 2.1/2 system at home. 1 - I get to enjoy music in a much better environment than in a car
Probably a bit against the DIY grain but I have a set of KEF Meta R3s on the way and a WiiM Ultra pre-ordered as my streaming/DAC/pre-amp. Still in the discovery stages of what I am trying to find for an amp and long term a sub.
Excited to read more here.
Currently a massive DIY car audio guy with a pretty competitive nationally ranked vehicle filled with Accuton Automotive, Focal Utopia, Brax, Mosconi and other nice SQ brands. Love the DIY side.
My truck's front stage:
Amp rack I built:
On to the home audio side:
Been looking to create myself a basic, but quality reference 2.0 or 2.1/2 system at home. 1 - I get to enjoy music in a much better environment than in a car
Probably a bit against the DIY grain but I have a set of KEF Meta R3s on the way and a WiiM Ultra pre-ordered as my streaming/DAC/pre-amp. Still in the discovery stages of what I am trying to find for an amp and long term a sub.
Excited to read more here.
17 year cicadas: 94.4dB on my porch in Chicago
- Everything Else
- 17 Replies
They’re HEEEEERE.
Spectrum is centered around 6KHz.
They started popping out of the ground a week ago. A force of nature like nothing you’ve ever seen. Millions of them.
Same thing 17 years ago. But now a couple hours south of here we ALSO have 13 year cicadas. Both broods occur together only one every 221 years. Thomas Jefferson was president last time this happened.
Spectrum is centered around 6KHz.
They started popping out of the ground a week ago. A force of nature like nothing you’ve ever seen. Millions of them.
Same thing 17 years ago. But now a couple hours south of here we ALSO have 13 year cicadas. Both broods occur together only one every 221 years. Thomas Jefferson was president last time this happened.
Intro - I've thrown myself in the deep end
- By BennnnNZ
- Introductions
- 5 Replies
Afternoon All.
I've been building a set of active 3 way monitors and I've finally got them "finished".
I'm use the term "finished" because the port length needs to be tuned and the dsp's setup.
Maybe assembled would be more accurate.
They're getting sent off to a guru to be set up properly, but I was keen to have a crack at sorting what I can prior to sending them off.
The crossovers are set as below:
With all the IIR / FIR / Gain adjustment per channel set to default/off, I get the following:
I've been digging around for guides to set this up, but I keep coming across info for setting a room up, rather than a speaker.
I'm hopeful someone can point me in the right direction.
Cheers
Ben
I've been building a set of active 3 way monitors and I've finally got them "finished".
I'm use the term "finished" because the port length needs to be tuned and the dsp's setup.
Maybe assembled would be more accurate.
They're getting sent off to a guru to be set up properly, but I was keen to have a crack at sorting what I can prior to sending them off.
The crossovers are set as below:
With all the IIR / FIR / Gain adjustment per channel set to default/off, I get the following:
I've been digging around for guides to set this up, but I keep coming across info for setting a room up, rather than a speaker.
I'm hopeful someone can point me in the right direction.
Cheers
Ben
Attachments
For Sale Harman Kardon Citation II amplifier - $2400 shipped
Here's a nice plug-&-play Harman Kardon Citation II amplifier with full rebuild. All original chassis paint and gold silkscreen lettering intact. Some paint missing from the transformers. Light scuffing on the faceplate. Visually a very presentable and clean amp.
Wired as-original in Ultralinear mode for full power.
Known history: I received this as part of a trade, non-functional. Only ~80% of the rebuild was complete at the time. I ordered a few parts from Jim McShane and finished the work needed, with some long-distance help from Chris Rice. Voltages were verified and then music tested in main system for a week.
*Rebuild includes:
Other details:
(1) Gold Lion KT-88
- extra tubes included;
(1) GE JAN-12BY7A
(1) GE 12BY7A
SOLD! $2400 shipped CONUS, fully insured, all fees included
(discount for local pick-up in 89147)
> Click here for more photos <
Wired as-original in Ultralinear mode for full power.
Known history: I received this as part of a trade, non-functional. Only ~80% of the rebuild was complete at the time. I ordered a few parts from Jim McShane and finished the work needed, with some long-distance help from Chris Rice. Voltages were verified and then music tested in main system for a week.
*Rebuild includes:
- Jim McShane Level II upgrade kit
- '2-A' coupling cap kit (Russian K40Y PIO and Solen film)
- '2-S' small value cap kit (RelCap film and silver mica)
- premium resistor kit (Dale wirewound)
- bias current modification (replace 15 ohm resistor with 18 ohm; to reduce current & retain correct "bias" mark reading)
- (4) Micalex octal sockets with ground tabs
- (6) Belton 9-pin sockets
- (1 Set) gold RCA jacks
- (1 set) OEM type speaker terminals
- (6) GE JAN-12BY7A tubes
Other details:
- new faceplate / bottom cover
- new chassis feet set w/ hardware (larger than original / rubber)
- new AC line cord, 3-prong
- ON/OFF power switch added
- power tubes installed;
(1) Gold Lion KT-88
- extra tubes included;
(1) GE JAN-12BY7A
(1) GE 12BY7A
SOLD! $2400 shipped CONUS, fully insured, all fees included
(discount for local pick-up in 89147)
> Click here for more photos <
Attachments
Scope Design: JFET Input EXICON Output 10 Watt Class A
- By lineup
- Solid State
- 157 Replies
The name of this amplifier is EXIAMP10.
Because the output devices are EXICON transistors and the target power is 10 Watt Class A.
The input is a quality JFET: LSK170.
I will test this amplifier in simulation. Also use a simulation oscilloscope.
AC Analysis and Fourier Analysis are also possible.
Post #85 and further there is a PCB.
Because the output devices are EXICON transistors and the target power is 10 Watt Class A.
The input is a quality JFET: LSK170.
I will test this amplifier in simulation. Also use a simulation oscilloscope.
AC Analysis and Fourier Analysis are also possible.
Post #85 and further there is a PCB.
An excellent source for Metric Fasteners
- Parts
- 2 Replies
My client and I decided that the stainless steel machine screws that were holding the Beyma AMT's faceplate on, in low-light conditions, looked like cat's eyes staring at you. Rather than painting them with a paint marker, I went in search of black metal replacements.
One supplier had a minimum quantity of... 500 pieces. Many wanted a 100-piece order. A couple wanted a 50-piece order. There was only one supplier that had no minimum quantity (but there was a $5 order minimum before Shipping). Photo is of Black Stainless Steel.
So, if you need metric fasteners, and don't want to buy 50 pieces, Belmetric is the answer.
john
One supplier had a minimum quantity of... 500 pieces. Many wanted a 100-piece order. A couple wanted a 50-piece order. There was only one supplier that had no minimum quantity (but there was a $5 order minimum before Shipping). Photo is of Black Stainless Steel.
So, if you need metric fasteners, and don't want to buy 50 pieces, Belmetric is the answer.
john
ESS Heil AMT-1 Defect?
I just received a pair of brand new Heil AMT-1 from ESS Labs, but on one of them, I noticed a strange defect(?). It appears almost as if somebody marked an "X" with sharpie/marker on the flat diaphragm before it was folded. I'm sure it functions fine but a bit concerned about resale value. So far no reply to my email and no answer on the phone. Anyone else ever see this sort of thing?
Low mid to go underneath Unity Horn
- Multi-Way
- 5 Replies
I have four 12NDL88 drivers to put below a unity horn I have designed. My aim is to do 150hz up to around 400hz which is why I have gone for angled baffles to move the acoustic center of the drivers closer together.
I have currently got a port either side to allow for space behind for the 12" driver but I might try and get it to fit with a single port on one side.
I started off by simming in hornresp to get something vaguely what I want.
I then drew it up and simmed it in Akabak BEM and my output is wildly different, I have checked the volumes and areas a few times. I checked the volume using Akabak by adding everything to the repository then using the meshing to calculate the volume. Some of my triangles are maybe a bit thin but I will redo it sometime, the LEM sim is the same though.
The impedence nearly matches in both
I have also drawn it up in LEM in Akabak, without the angled baffles, to compare and got the same results as BEM
Does anyone know what the reason why the sims are so different? I kinda want to build it and measure it to see how it will do
I have currently got a port either side to allow for space behind for the 12" driver but I might try and get it to fit with a single port on one side.
I started off by simming in hornresp to get something vaguely what I want.
I then drew it up and simmed it in Akabak BEM and my output is wildly different, I have checked the volumes and areas a few times. I checked the volume using Akabak by adding everything to the repository then using the meshing to calculate the volume. Some of my triangles are maybe a bit thin but I will redo it sometime, the LEM sim is the same though.
The impedence nearly matches in both
I have also drawn it up in LEM in Akabak, without the angled baffles, to compare and got the same results as BEM
Does anyone know what the reason why the sims are so different? I kinda want to build it and measure it to see how it will do
Help identifying this JBL driver
Hello, I need help identifying this JBL 12" eight ohm woofer, please.
The W5685 number seems to be the recone number.
The W5685 number seems to be the recone number.
Bought my first rig!
- By Jjones03
- PA Systems
- 16 Replies
Hi all,
I’ve found a small soundsystem on Facebook market place that I went and bought today! I was hoping for help on the next steps from here…
It’s 2 Fane 15” scoops unloaded (scaled down to 12”)
2 es18 loaded (scaled down to 10”)
And 1 8” midtop with 1” cd horn (need new cones)
My hope is to have it for a small house party/ outdoor system, and so far I think I need to: load remaining speakers, get atleast 4 channels of amps for each different driver, crossover and limiter (which will plug into laptop/decks) and I’m heavily considering buying a 18” hog scoop premade to reinforce bass
I’ve found plans for the scoops and es18 full size, if I can confirm it’s a scaled down version, should I plug these values into hornresp/akabak and see what it gives me? Seller gave me link of what he put in the scoops,(https://www.thomann.de/gb/the_box_speaker_12_280_8_w.htm) and I was thinking any 8” mid woofer with 1” cd will work.
i have a calibrated microphone, so my first step once I’ve verified the speakers are a perfect(ish) scale down is to measure the frequency response of the kicks, and find a suitable driver that goes high enough for the scoops and low enough for the top? Then once I know the limiting spl get amps that will drive all of them to atleast that spl with headroom. I’m also between a rack DSP like an ultra drive or DMX or daisy chaining 2 ADAU1701 together to get 7 out, only problem being it’s unbalanced so length might be an issue
My questions are-
How do I pick the right drivers/ how do I ensure they’re suitable? Is it just a case of plugging different specs into hornresp and akabak till I get a good response?
Will an 18” hog scoop (with pd1850) intergrate with the system well? Is there any way in knowing without picking a driver for the rest of the system?
And is there any parts I’ve forgotten?
If you’ve read this far, Thankyou!
I’ve found a small soundsystem on Facebook market place that I went and bought today! I was hoping for help on the next steps from here…
It’s 2 Fane 15” scoops unloaded (scaled down to 12”)
2 es18 loaded (scaled down to 10”)
And 1 8” midtop with 1” cd horn (need new cones)
My hope is to have it for a small house party/ outdoor system, and so far I think I need to: load remaining speakers, get atleast 4 channels of amps for each different driver, crossover and limiter (which will plug into laptop/decks) and I’m heavily considering buying a 18” hog scoop premade to reinforce bass
I’ve found plans for the scoops and es18 full size, if I can confirm it’s a scaled down version, should I plug these values into hornresp/akabak and see what it gives me? Seller gave me link of what he put in the scoops,(https://www.thomann.de/gb/the_box_speaker_12_280_8_w.htm) and I was thinking any 8” mid woofer with 1” cd will work.
i have a calibrated microphone, so my first step once I’ve verified the speakers are a perfect(ish) scale down is to measure the frequency response of the kicks, and find a suitable driver that goes high enough for the scoops and low enough for the top? Then once I know the limiting spl get amps that will drive all of them to atleast that spl with headroom. I’m also between a rack DSP like an ultra drive or DMX or daisy chaining 2 ADAU1701 together to get 7 out, only problem being it’s unbalanced so length might be an issue
My questions are-
How do I pick the right drivers/ how do I ensure they’re suitable? Is it just a case of plugging different specs into hornresp and akabak till I get a good response?
Will an 18” hog scoop (with pd1850) intergrate with the system well? Is there any way in knowing without picking a driver for the rest of the system?
And is there any parts I’ve forgotten?
If you’ve read this far, Thankyou!
Experience with ACA Mini in parallel mono mode
- By christiang
- Pass Labs
- 5 Replies
Hello all.
I was quite satisfied with my two ACA amps in parallel mono mode driving DIY 4 ohm speakers (woofers are double voice coil units wired in parallel). Summer is over up here and I am contemplating again Class A operation for the Winter... I already built an ACA Mini (see photo, below the two ACAs) as a stereo amplifier, but I have another complete kit yet to be built. Before I go ahead and make myself a pair of Mini Monoblocks, I would like to hear from folks who have used their ACA Mini in parallel mono mode. That would certainly help. Cheers!
--Christian
I was quite satisfied with my two ACA amps in parallel mono mode driving DIY 4 ohm speakers (woofers are double voice coil units wired in parallel). Summer is over up here and I am contemplating again Class A operation for the Winter... I already built an ACA Mini (see photo, below the two ACAs) as a stereo amplifier, but I have another complete kit yet to be built. Before I go ahead and make myself a pair of Mini Monoblocks, I would like to hear from folks who have used their ACA Mini in parallel mono mode. That would certainly help. Cheers!
--Christian
For Sale Audio Nirvana Super15 Alnico
- By baggerbole
- Swap Meet
- 27 Replies
Sold! To a very pleasant buyer 😉
For sale are 2 Audio Nirvana Super15 Alnico speaker chassis.
I bought them from Dave in 2019. The speakers have been used for 1.5 years and have around 500-600 hours of use. So they've just been played in properly...
The condition is very good. The sound is great, Dave said: "This is the best sounding speaker in the world" 😉
I would like €650 for it. Shipping will be in the original packaging to wherever you want.
Driver for Array? Visaton SC4.6FL 1.6" x 2.4" Full-Range Speaker
- Planars & Exotics
- 17 Replies
Has anyone used this driver for anything, Visaton SC4.6FL 1.6" x 2.4" Full-Range Speaker?
It appears to have a great frequency response and might be good as a driver for arrays. The downside is the power handling is only 5 watts. I don’t see that as an issue if 24 of them were used in a tower. $12.14 each!
Here is a link to PE, but I’m sure you can find these elsewhere. https://www.parts-express.com/Visat...le-Full-Range-Driver-8-Ohm-292-658?quantity=1
It appears to have a great frequency response and might be good as a driver for arrays. The downside is the power handling is only 5 watts. I don’t see that as an issue if 24 of them were used in a tower. $12.14 each!
Here is a link to PE, but I’m sure you can find these elsewhere. https://www.parts-express.com/Visat...le-Full-Range-Driver-8-Ohm-292-658?quantity=1
Polystyrene capacitors
- By StingRay85
- Tubes / Valves
- 9 Replies
Is anyone familiar with NSF polystyrene capacitors? These all seem to have the "KF59" mark on them. I just bought an entire set of those caps, all are 2% tolerance 400V, going as high as 89800 pF, NOS presumably from the 60s-70s. The high voltage application is why I added this topic in the tube section.
Bought them in a lot with Philips mustards caps, and to be honest I'm only interested in those as my hobby is guitar and not Hifi. I'm planning on getting a fair price for the polystyrene caps where buyer is also very happy with, and give it entirely to the lady from which I bought the lot. She inherited it about 20 years ago from her father, and left it untouched in her garage.
Any help would be appreciated. Added some pics to see what I'm dealing with.
Bought them in a lot with Philips mustards caps, and to be honest I'm only interested in those as my hobby is guitar and not Hifi. I'm planning on getting a fair price for the polystyrene caps where buyer is also very happy with, and give it entirely to the lady from which I bought the lot. She inherited it about 20 years ago from her father, and left it untouched in her garage.
Any help would be appreciated. Added some pics to see what I'm dealing with.
Attachments
QB4 in triode
- By toshiba_nz
- Tubes / Valves
- 3 Replies
I just picked up a Philips (Holland) QB4/1100
What would be a good sounding OP in triode?
Cheers
4-400a:
What would be a good sounding OP in triode?
Cheers
4-400a:
For Sale TAD drivers and networks for TSM-1
SOLD
Excellent condition drivers:
1 pair of TD-4001 compression drivers.
4 TW-1601a 15" woofers
1 pair cloned TN-1 networks, with charge coupling adding to HF section. Wired with 16ga Silver wire in cotton insulation.
$7500 OBO for the set
Excellent condition drivers:
1 pair of TD-4001 compression drivers.
4 TW-1601a 15" woofers
1 pair cloned TN-1 networks, with charge coupling adding to HF section. Wired with 16ga Silver wire in cotton insulation.
$7500 OBO for the set
Attachments
Oscillating/motorboating SE EL84 Amp
- By JMartell
- Tubes / Valves
- 74 Replies
Hey folks!
Recently bought myself a single ended E80CC/EL84 amp from a fellow enthusiast. First one I've ever had, and I primarily bought it to use with the Beta 8-loaded Dallas horns I'm building (Follow that bit here).
To test the amp I hooked up some of my fathers' cheap logitech satellite speakers. Whatever was there sounded fine, and now knowing it worked I felt confident connecting the Beta 8's just for fun. After a minute or so, I noticed some low-frequency stuff happening and when I looked at the speaker cones they were oscillating something fierce. I cut power and proceeded to sweat bullets. Let it cool down and switched the tubes around, same thing happened. Went ahead and filmed it, oscillations visible only in the last few seconds.
I asked the guy I bought it off of if he'd ever had any issues of the sort, and he told me no. He'd only built it a few months back and had been running it for extended periods regularly through both his BR-mounted Flat 8's and some 3" Tang Band speakers. Upon request he provided the schematics for the amp -- Some sort of DIY kit he had bought off of Ebay. I'll be posting them below.
Only thing about the schematic that worries me is the absence of any kind of resistor on the screen grid, feel like you usually see those on pentode amps. That said, I'm still fairly new to valve amp design so any input from the sages here would be much appreciated.
In the meantime I'm going to borrow some 100x probes from work and feed it with my signal generator to see if I can make any sense of it. Have plenty of old radio drivers that I don't mind bricking for science.
Cheers,
J
Recently bought myself a single ended E80CC/EL84 amp from a fellow enthusiast. First one I've ever had, and I primarily bought it to use with the Beta 8-loaded Dallas horns I'm building (Follow that bit here).
To test the amp I hooked up some of my fathers' cheap logitech satellite speakers. Whatever was there sounded fine, and now knowing it worked I felt confident connecting the Beta 8's just for fun. After a minute or so, I noticed some low-frequency stuff happening and when I looked at the speaker cones they were oscillating something fierce. I cut power and proceeded to sweat bullets. Let it cool down and switched the tubes around, same thing happened. Went ahead and filmed it, oscillations visible only in the last few seconds.
I asked the guy I bought it off of if he'd ever had any issues of the sort, and he told me no. He'd only built it a few months back and had been running it for extended periods regularly through both his BR-mounted Flat 8's and some 3" Tang Band speakers. Upon request he provided the schematics for the amp -- Some sort of DIY kit he had bought off of Ebay. I'll be posting them below.
Only thing about the schematic that worries me is the absence of any kind of resistor on the screen grid, feel like you usually see those on pentode amps. That said, I'm still fairly new to valve amp design so any input from the sages here would be much appreciated.
In the meantime I'm going to borrow some 100x probes from work and feed it with my signal generator to see if I can make any sense of it. Have plenty of old radio drivers that I don't mind bricking for science.
Cheers,
J
A surprisingly good alternative for the Jordan JX92s...
- By konstantin
- Full Range
- 9 Replies
Attachments
The Chill-baffle3 speaker page
Hi Folks.
I just finalized a webpage to describe my latest three-way open baffle speaker, see:
https://www.fedde.nu/audio/chill-baffle3.html
It uses an 15" daudio woofer, 6" 18 sounds 6ND430 mid driver and ESS AMT tweeter (aka "Heil AMT") with Harsch XO and Hypex Fusion 253 plate amps. More details on the webpage.
I just finalized a webpage to describe my latest three-way open baffle speaker, see:
https://www.fedde.nu/audio/chill-baffle3.html
It uses an 15" daudio woofer, 6" 18 sounds 6ND430 mid driver and ESS AMT tweeter (aka "Heil AMT") with Harsch XO and Hypex Fusion 253 plate amps. More details on the webpage.