I will sell various sockets for radio tubes ceramics - carbolite

payment paypal
possible exchange for radio tubes

1) 11pin relay panels 24 pieces used for $1 each

2)

3) LOCTAL panels (4P1L\7N7\EBL21)
ceramics in a cage with metal ears 4 pieces used for $2 each
carbolite in a cage with metal ears 1 used 2 new $6 all
carbolite with metal bracket Germany new 2 pieces $3 all
ceramics lamellas 8 new 2 used $15 all

4)

5) Panels ceramics GU50\GU15
5 pieces ceramics 1carbolite $7 all

6)
Caps 8 pieces from TVS
Caps 5 pieces closed 6f5\ef37\6j7
Caps 36 pieces open various 6f5\ef37\6j7
10$ all


7)
Caps 807 tube carbolite\plastic 6 pieces 6$ all
Caps 811 tube open 6 pieces 8$ all


8)
panel 845\211 lamp ceramics 15$
Panels ceramics for 813\4E27\6A6\gu13
RCA UT-104 new 12$
JOHNSON 237 used 10$
6с33с panels thick crimping 2 closed one open 15$piece
good quality


9)
octal 8pin panels ceramics
round panels with good contacts 25pieces used -100$ all


10)
octal 8pin panels made of textolite
22 panels new and used 25$ all


11)
LOCTAL 9pin panels (EF50\EF54)
thick ceramics with British ears 2pieces used
ceramics with ears 3 pieces 160 UAH used
solid ceramics 1 piece used
30$ all

panels 5pin AKORN (957\955\954)
ceramics 8 pieces 15$ all


12)
Panels for RV12P2000 used 3 pieces -10$ piece
panel for RV12D60 1 piece -10$

Panels for Y8 EL11\EL12\EF12 carbolite
7 pieces round Germany -8$ piece
3 pieces oval Germany -8$ piece one glu


13)
panels g807\56 UX5
used textolite panels использованные 3 pieces $2 piece
carbolite panels used 1 piece $2
solid ceramic panels with ears used 1 piece $8
ceramic panels without rings used 3 pieces $6 all

panels 2A3 carbolite UX4 without rings 2 pieces $4 all

panels 6A6\53\310A carbolite UX6 without rings 2 pieces $6 all


14)
panels for GK-71
carbolite collet 3 pieces $15 all
textolite paired panel with holders $8


15)
panel 12s3s\LD1 one with screen $10 pair

Panels for spider AL4\EL3\AF7 carbolite
new 8 pieces -40$ all
soldered 1pc -3$
soldered 1pc adapter EL3\EL6-> 6L6 -3$
Germany original for 3 ears used 2pcs 20$ pair


16)
octal 8pin panels made of carbolite with a nut
black panels mount nut 10pcs - 2$ each

octal 8pin panels made of carbolite with ears Germany
12pcs B\U and new -50$ all


17)
octal 8pin panels made of carbolite with ears
23 panels used - 2$ each


18)
octal 8pin panels made of black carbolite
with metal clip and ears used - 19pcs 2$ each
with metal clip and ears used collet 1pc -10$
mounting panel USA used 1 piece 5$


19)
Octal 8-pin panels made of brown carbolite with metal ears
in a metal clip 20 pieces used 4$ each


20)
Octal 8pin panels made of carbolite
under a bracket with two screws - without a bracket used
good quality contacts 12 pieces 6$ all
collet carbolite panel with crimping 1 piece 10$

collet ceramic panel with crimping 1 piece 10$
2A3 panel ceramic new gold 30$ pair

As we all know, the resonance formula for second-order filter is given by f = 1/(2 x pi x sqrt(LC)). As can be seen, there are two variables involved which are the product of inductor and capacitor values used in the filter.

However, in third-order, there are three components used which should mean the formula would have been changed to have three variables involved, and four variables for fourth-order. Do I understand correctly? If so, what are resonance formulas for third- and fourth-order filters, respectively.

Finally, the first-order is the only case that has no resonance formula because there’s no two elements to interact with each other as the higher-orders, do I understand it correctly?

Currently staying in a hotel in Kensington that used to be a townhouse. The conversion it fairly recent, maybe 2-3 years old. Rented the 17 m2 deluxe studio. It's more like a dungeon. The room door is underneath the main entrance stair, which is not uncommon in townhouses, but the room itself is not underneath the main building but it extends towards the street into the front yard and is completely below street level. Google AI tells me hotel rooms in London should at least have 2.3 m height but who trusts AI? Does anyone happen to know the regulation and what body would enforce it?

The only 1 m² that has about 2.3 m is right in the entrance, underneath the pedestal of the building entrance. The bedroom is more like a 5 m² cave with a maximum height of 1.95 m in the apex of the vault of the ceiling. It gets lower to the sides and the back of the room. The dining room has a maximum height of 1.8 and gets lower to the back and one side. The staff have been rather unhelpful about getting me another room, so I'd like to present them with the regulations.

(needless to say that is only about 14 m² of you subtract the massive interior walls, and I am not even sure those areas below 2 m count)

Hello everyone. I am helping a friend with a fullrange project. He wanted some Voxativ drivers but, saw the price and just to much money. We stumbled upon a company called Sonido fullrange driver's. Looks really nice. Not to many reviews but the gallery has a lot of customers using these driver's. Also they are not to much money compared to other fullrange driver's. I did e mail the owner very nice and very helpful. I like that. So what are your thoughts and have you heard or know of anyone that has used or heard these fullrange driver's? Thanks jm

Meter LOT

LOT photo 1-5

60mm*60mm overall dimensions
47mm*47mm mount

0-5MA 23.3ohm metal screen
0-50V 5.84kom metal screen
0-50V 5.86kom metal screen
0-50V 5.86kom metal screen
0-50V 6.86kom metal screen
0-300MA 0.4ohm metal screen
0-30V alternating current arrow deflects

0-300V 3.3mоm arrow deflects

82mm*82mm overall dimensions
65mm*65mm mount
0-100microАmp 454ohm

75mm*75mm overall dimensions
64mm*64mm mount
0-120 TV-7 meter ? 2.26kohm

Level indicator
1) 481 ohm
2) DEAD
3) DEAD

90$ US for the whole lot

LOT foto 6-7
110mm*95mm mount

0-100microAmp 750ohm
0-200microAmp 70ohm
0-300microAmp 770ohm
0-300microAmp 330ohm
0-50microAmp 2kohm
arrow does not reach the end
repair required
0-10mV 10ohm

60$ US for the whole lot

LOT foto 8-9

47mm mount
0-100microAmp 3.04kohm
small size there are 3 pieces of such meters

80mm*100mm overall dimensions

60mm*80mm mount

0-250MA 0.4ohm

66mm-67mm overall dimensions

WESTON 0-200microАmp -DEAD winding burnt

WESTON 0-500MA 0.7ohm

WESTON 0-100 1.2MA 10.8ohm

88mm overall dimensions
WESTON 0-1MA 100ohm

90$ US for the whole lot

LOT foto 10-11

wire coils
for making precision wire resistors
and shunts for instruments
with different wire diameters
photo 10 with carbolite base
photo 11 with ceramic base

90$ US for all coils


I ask 300 USD for everything + shipping - or best offer

Payment via Paypal

FT teflon capacitors and K72p-6 teflon sealed capacitors


all capacitors are checked for tolerances, mostly slightly more than nominal
a small number less than nominal
they are 5% 10% a small number 20%
to increase the capacity you can simply parallelize the capacitors
200 volts for transition
600 volts for power

200 volts 600 volts are working voltages these capacitors
allow this voltage to increase up to 40%

paypal payment

exchange for radio tubes is possible by agreement

1 K72p-6 0.1*200V-1pcs 68N*200V-2pcs 56N*500V-3pcs 18N*200V-2pcs 10N*200V-1pcs 1n*500v-2pcs
+ CAP Siemens 0,5mF*220V\400V ??
60$
2 FT-1\FT-2 47N*200V-3pcs 22N*600V-1pcs 22N*200V-1pcs 18N*600V-2pcs 15N*200V-1pcs
10N*200V-3pcs 10N*600V-1pcs 8N2*200V-2pcs
30$
3 FT-1 3000pF*200V-151pcs new in factory packaging
+ FT-1 3000pF*200V-55pcs used
90$
4 FT 5600pF*200V-1pcs 4700pF*200V-1pcs 4300pF*600V-7pcs 3900pF*600V-8pcs 3000pF*600V-8pcs
1600pF*600V-2pcs
2200pF*200V-2pcs 1800pF*200V-5pcs 1300pF*600V-2pcs 1200pF*600V-2pcs 1100pF*600V-4pcs
1000pF*600V-19pcs
820pF*600V-23pcs 680pF*200V-4pcs
510pF*600V-5pcs
50$
all together 180$

I've come up with an unusual amplifier topology involving boostrapped stuff, and that seems to have, shall we say... non-optimal clipping behavior. So it looks like I'm going to need a pre-clipping circuit.

Of course it should not distort at all until it does.

I've sketched a number of attempts, all involving bootstrapping the clipper diodes to reduce distortion by keeping voltage across them constant, which avoids nonlinear capacitance effects, leakage, etc. The bootstrap voltage is itself clipped by another pair of diodes, so when it reaches the limit, the other side of the diodes no longer follows the input signal and they begin doing their job.

The four ones on the left use diodes or transistors as diodes. They're strictly at the input of the amp, so they need an opamp buffer for the bootstrap voltage. The one on the right deletes the opamp by using the amp's output voltage (the power amp is VCVS E1) and using BJT emitter followers as diodes. Basically the two transistors' bases follow the input signal so they do nothing, until the diodes on the right conduct, at which point the transistors limit the input signal.

On the left is a sinewave with a smashed top.



And here is THD vs input level. Simulations are sometimes slightly optimistic, but it looks like "no distortion before it has to begin clipping" is achievable.



Thoughts?

Wondering if there is any evidence that Silver solder, or other alloys, have beneficial results?

I have two identical stereo headphone output devices. I want to mix the two into a single headphone output. I'd like to do it passively as there's enough batteries to maintain as it is. Each device specs a 10 Ohm output impedance. I'm using ordinary, consumer level headphones. Dont need to go as loud as each device to be mixed can individually.

An appropriate circuit to me would be just a pair of resistor from each channel output, each connected to the headphone coil. But the resistor values? I can only guess. What would be the optimal resistances for such a mixer? Thanks!

Here is a project that I designed in 2020. It is a 3 Band Equalizer and a low wattage amplifier. I had a pair of clean bookshelf speakers but the low frequencies were lacking so I decided to build an equalizer that could boost the low end. It is meant to drive the input of a power amplifier or low power headphones or earbuds. It could be useful to someone who uses book shelf speakers as a main system or someone who just wants a low power 2 channel 3 band equalizer. It does have a noticeable pop at turn on because the TL084s that I used have a non-linear startup condition. It does work fine for me and maybe it will work fine for another DIY builder. The roll off frequencies are 400 Hz and 5000 Hz as designed but can be changed to what ever some one wants. It can use a 3v to 15v DC power supply but I usually run it at 12v. The parts are labelled on the circuit board and I sent the Gerber files in case someone wants to give it a try. The surface mount resistors are 1206 in size. The schematic shows one channel of the design.

Hello,

I've joined to ask a specific question about programing a Bluetooth audio module. This seems to be the main place people talk about them.

Is there anything in particular I have to say here?

Somebody in Melbourne is downsizing and I've just agreed to buy a lightly used Shiva from them.
Comes in a box but I think that the supplied box might not be the best
So what's a reasonable compromise sealed box for a 12" Shiva driver and how does any of the current Dayton subs compare?
Haven't picked it up yet so I don't know which version it is.
But I think I can afford to take the chance at $50-

I am adding LL1539 output transformer to old TPA Buffallo III for SE output
Currently I wire like this:
Primary:
Wire pins 2,4,5 to +OUT of IVY
Wire pins 1,3,6 to -OUT of IVY
IVY GND not connected

Secondary:
Join pin 7 to 11
Wire pin 8 to +RCA
Wire pin 12 to -RCA

Sound is nice but hum. Do I need to connect GND to anywhere to get rid of hum?
Thank you very much

(edit)
Note - what started out as an attempt to evolve the p3a has ended up as a complete redesign of every stage. This amplifier is my best. Anybody wanting to build this amp for DIY purposes (only) should find all they need in this thread.

Some useful posts:

#232 - discovery that dual colour LED has insufficient headroom for the ‘green’ side to work (my fix is on #314)
#238 & #242 - discovery of, and changes to deal with cross-conduction at v. high frequencies
#314 - fix to pcb for very first incarnation (corrected on subsequent pcb layouts)
#407 - pcb files and (a now old) bill of materials
#597 - a bill of materials for Mouser
#604 - my as-built schematic (with C3 shown wrong way around, should be installed + terminal to ground)
#632 - a comment on bias for the output (60mA) note original pcb has a silkscreen error with the bias and dc offset adjust labels swapped around
#645 - a note on correct orientation of C3 (shown wrong way on pcb silk screen)
#768 - some photos and comments on how the power devices mount under the board and the use of some TO-126 transistors with legs removed are used as 'spacers'
#772 - some photos and comments on incorporating an output inductor into the wiring
#950 - updated bill of materials (BOM) based on Digikey.ca
#994 - spice file for the amplifier
#1131 - KiCad files from 'longface54'
#1215 - updated KiCad files from ‘jpk73’


Builders: Go slow, solder all the small parts first and clean off the flux before moving on. Read the thread, I know it's long but there's advice in there for you.


Builders Comments:

'Ranchu32': "this is a fabulous amp; one of the best. I love the sense of energy and the dynamic performance, which I feel is somewhat lacking in the basic P3A. But it loses none of the P3A's best qualities: that beautifully smooth and detailed midrange, and crystal clear highs." "the more time I spend with TGM8 the more impressed I am. Having now heard the VSSA, I am equally impressed and it is deserving of the high praise it is getting around here. But your design is in the same league: similar in many respects and subtly different in others. I suspect TGM8 will better suit my tastes"

'Lordearl': "As to the sound - phenomenal, incredibly relaxed, yet still highly detailed! Tempted to use the good channel on my better speakers just to enjoy it for a while! A very inviting sound for sure." "My initial impression (mono only) is the same, the low frequencies are crisp and punchy - never heard anything quite like it. The treble easily rivals my 6L6 ultra linear push pull amp with Tango output transformers, plenty of air, no fatigue (also no apparent dumbing down of the sound!). Makes you realise why you loved audio in the first place!"

'still4given': "You done good Gareth! I can see why you were so satisfied. I've got some Gerry Mulligan playing through it right now and it is beautiful. Thanks for sharing this with me." "It really is very nice sounding. Seems as good as the VSSA and that is one fine sounding amp."

'pronk': "I originally planned to build just two boards but liked the TGM8 so much that I built six (four to power my LXmini and two for my home office). Note these boards are densely populated and have about 30 SMD components. This is probably not something you can throw together in an evening. The end result is definitely worth the effort. This is one of my favourite amplifiers. Sound quality, particularly bass, is excellent. I appreciate the built-in speaker protection which makes this amplifier more of a complete product safe to use with expensive speakers."

'RCruz': "Finally had the opp to listen to it and i am really pleased with the sound...the best bass grip I heard in years"

'auriga2001in': "Thanks for the wonderful amp. I have two amps (BJT, Latfet outputs) running wonderfully for a year now."

'pinnocchio' "This amp has some really good grip on the bass driver, very fast and precise. I haven't done all the tests yet but looking very good so far."

‘Do’: “Amps are working perfectly. I truly love the bass from this amplifier, very hard to believe until you hear it! Solid, in control of the speaker, I mean just perfect!”

'audiorasp': "I really like these amps! They have been powering my LX521's for about month now and I find their presentation to be detailed and powerful, but in a relaxed way, if that makes sense."

'longface54': I decided to go for it. I had some PCBs made, using the published gerbers, and built two amps. Powered each one up on the lab PSU and, bingo! They both worked first time and the DC offset and bias was very stable... Right away the sound had such authority and pace but in a relaxed and musical way with a softness in the upper registers. ... I’m listening as I write so I’m off to turn the volume up... just a little.

’jpk73’: I connected my speakers and played some music: excellent!!! I am very happy 👍🙂.

'chat72': Ok finally they sing!!! Sound good especially high.

Also - I can not edit attachments to the first post, the schematic you see in this first post shows my initial scrawl - not to be confused with the schematic of the as-built amplifier.

I got it a month or two ago and barely used it as I already have Agilent and Fluke DMMs. $80 plus shipping in US.

Here is a quintet (x5) of NOS, vintage, Philips (also BC Components) Polypropylene Caps 0.01uF 63V 1%

All are brand new, from the same batch and individually tested

Philips Part No. 2222 460 41003

They are approximately 15mm long, 6mm diameter

These superb caps are no longer manufactured but are made with the highest quality dielectric for lowest loss

Ideal for the most demanding applications including filters and tuned circuits

I'm thinking USD 15 plus postage or open to offers

Cheers, Ralph

Hi All...

I'm looking for repair info for the Harmon Becker BE 7021

So far there's a few youtube videos. I'm looking for anyone that has successful repaired one or if anyone knows of any repair info on it?

Supposedly they can be swapped out with a Hyundai model for a 2011 Hyundai Equus

So I'm about to take a stab at repairing an alpine head unit for a car with non working preouts. There are a number of small smd components and some are unmarked. I'm assuming there's a resistor, or capacitor as small as 0401 causing this, hopefully just an IC, but how would I calculate the value of the part if it's blown or bad?

Just another pilgrim wandering the path. I was having a rough spell when a voice from above yelled: "just buy some nice speakers and enjoy yourself".

I then "entry leveled" myself with some Def Tech towers, only to blow one out watching Furiosa, which was worth it. Fixed it with a warranty part-- realized they're not complicated things. Later when a Demand D17 showed up with a broken inductor, I soldered it back on after learning how to solder (it still had silver tips).

I'm trying to hybridize a theater/stereo setup with a Def Tech DM30 center, two Demand D17 towers, and BP 9020 surrounds. I am wired for 2 wall and 2 ceiling speakers, but they're not in good spots for atmos, and it's 4 speakers wired to 4 posts, needing a lot of juice. I'm bi-amping my D17s instead, for now.

Running it all with only an Onkyo 7.2 with 100 watts into 8 ohms. The D17s, I hear, should get 300-500 watts with high damping. Kinda want to restore one of those 80s amps people love, but doing so without harming myself would be nice.

My wife was happy with two 9020s, so I've been pushing uphill. Wish me luck.

Cheers!

Generally regarded as the most advanced preamp of its day. (1973 on)

But who designed it? Anyone know?

This thread is for Quasimodo results ONLY.

Please NO COMMENTARY HERE. (For comments, please use the Simple, no-math transformer snubber using Quasimodo test-jig thread.)

[Note: it might be nice to highlight any non-standard Cx/Cs values in red.]

.

Looking for opinion on the best 7k primary output transformers for a 46 strapped-in-triode for use in a Single Ended amplifier. I know that Hashimoto, Tamura, and Tango make or made 7k primary transformers but their low-end bass performance is curtailed to 30 to 45 Hz. Are there any 7K OPT that go down 20Hz or less? Did MagneQuest ever produce a 7K transformer? I know that they did a 6K FS-007.

Tribute Audio use to produce excellent 7K transformers. Are there any other high quality 7K OPT available today that deliver great bass from a 46 strapped for triode operation?

What is the best 7K OPT for this application in your opinion? Whether still produced or not, which OPT’s stand out with 7K primaries?

Thanks in advance. Your opinions and guidance is appreciated.

Mosfet F6 Illustrated Build Guide

The Firstwatt F6 is a power amplifier from the brilliant mind of our technical, spiritual, and menu advisor, Nelson Pass.

The F6 is unique in that it uses a transformer for phase inversion, and both phases (The ‘push’ and the ‘pull’) of the amplifier are powered by an N-channel device.

This guide uses this PCB set — F-6 clone boards (2 PCBs, makes 2 channels; Rev 2.0) - Circuit Boards
Or here, the PCB with transformer bundled - F-6 Board + Transformer Kit – diyAudio Store



SCHEMATIC

The Schematic can be found here -



CHANGES TO THE SCHEMATIC - Change Z1, Z2 to a value higher than 5.1V if you need more bias. Increase in ~.5v steps until you can bias properly. The 1N4xxx series diodes are used here, 1N4733 is 5.1v, 1N4734 is 5.6v, 1N4735 is 6.3V, etc...

Suggested change, make R11, R12 110ohm. More information can be found in the BOM.

And an example PSU is here -




diyAudio PSU v3 build guide — diyAudio Power Supply Circuit Board v3 illustrated build guide



CHASSIS

The example amp is build into a diyAudio Deluxe 4U chassis — Deluxe 4U "Jack of all Chassis" (All Aluminum) V2 - Full width with 40mm Heatsinks - Chassis

Also utilized was the diyAudio Premium back panel parts kit — Error 404 - Page Missing

ASSEMBLY



Here are the PCB. The production boards are blue, and have some very slight changes to the silkscreen, but are otherwise identical.

Note that the PCB are a matched pair, not 2 of the same PCB. This is to facilitate keeping the input transformer as close to the back wall (and away from the power transformer) as possible.


Stuff resistors first.


After the resistors, stuff the larger components. Jfets, pots, capacitors, etc…


A stuffed PCB, sans transformer and LEDs (Didn’t have any blue ones on hand. 🙂 )


Input transformer. Note that on pair of pins is slightly narrower than the others. There are corresponding pads on the PCB for the narrow pins.


Transformer mounts here.


Both transformer mounted.


Remember, for best heatsink efficency, the mosfet should mount towards the bottom. This heatsink will make the left wall of the case.






You can see all the wiring of the PCB in this photo. (Red Black Green) is from the PSU, (Black White) is to the speaker posts, and the thin coax connects RCA to input.




Black is PSU GND and Speaker negative
White is Speaker positive
Red is V+
Green is V-



Input wiring from RCA




Completed, working amp. Need only to finish assembling the chassis around it.
(The black box on the transformer lead is a clamp-on ferrite clamp. Necessary? No. Might it help? Yes.)







POWER SUPPLY


IEC socket. You must wire the fuse holder to the switch as shown.


The long wires go to the terminal block with CL-60s, line cap and then the transformer primaries. I needed a bit huskier wire for the safety earth, and added the yellow for clarity.


PLEASE NOTE - this shows 120VAC wiring. Please consult your transformer for proper wiring for other voltages.
Into the block you can see the thermistors and cap, the AC mains from the IEC switch (Red Black) and the transformer primaries (Black Brown White Orange)


Safety earth and the CL-60 used to elevate PSU ground.


Two things to note - 1) I didn’t know if the power transformer was going to magnetically couple with the input transformers, so I wanted it as far away as possible. This will be almost touching the front plate. The L bracket was something I had from a salvage broken amp, so I can’t suggest a part number. Sorry. 2) Although I didn’t use the current PSU PCB, you can see that there is sufficient room (barely) for the board you can buy from the store.


I used an older diyAudio PCB that I had on hand, mainly because I really wanted to use it up.


Bridges mounted.


Wiring up the PCB.


More wiring.

For those of you wondering why I choose to have 2 big caps on one side and 4 on the other, it’s simply because I had those caps in my box. There’s no gain nor detriment to doing it in this manner.




The secret to clean wiring? Simple - start with your leads overly long and trim as you need to, and use lots of zipties. 😀


You can see the connections from transformer secondary to bridges and from bridges to PSU board.


PSU lit up.



TESTING AND POWERUP

Test PSU first for proper voltages BEFORE connecting amplifier circuit boards.

Then, connect only one amp PCB at a time.

Power Up

I suggest starting with a meter across the 0.47ohm source resistor, and watching it as it turns on, you want to have less than .5V across it to begin, turn it down with P2. If you start with the pot in it’s default position, it will most likely have too much bias initially. Turn off the power, turn down P2, and try again.



BIAS


P2 is marked BIAS on both PCB. Adjust this pot as necessary to set bias. Please note that as the pots and source resistors have the 1000uF capacitor in-between, the adjustments will happen in slow-motion and take a while to stabilize. Make small adjustments and wait as necessary. Patience is a virtue.


With DC voltmeter across the 0.47 source resistor, start by setting a bias reading of .5V (500mV) This will give a current of 1.05A, (.5V / 0.47ohm = 1.05A) which with a 24V rail gives about 25W of heat. Then zero your DC offset. Once you are satisfied that everything is stable and happy, you may increase the bias if you choose.

Remember the 3 rules of maximum bias… stop when you reach any of these -

Heatsink of 55C and/or Transistor pin 2 65C
Total bias , both channels, (in watts) of no more than 1/2 the power transformer’s VA
1/2 the maximum dissipation (in watts) of the output device. In the case of the IRFP240, it’s a 150W device, so no more than 75W. (Which is really, really hot…)

Generally, you will reach the 65C limit of the transistor before anything else.



OFFSET

P1is marked OFFSET on both PCB. Adjust as necessary to set 0V DC across the speaker terminals. Again, because the capacitor needs to charge and discharge as you make changes to the pot, any input to the pot will take some time to display on the meter, and it will seem as if it’s reacting in slow motion. This is normal.

Lightbulb Mains lead notes -



Please note that it must be an incandescent light bulb, not an LED or Florescent.
If the bulb ever turns on and stays bright, you probably have a short.

Normal operation when turning on a cold amp will have the bulb glow bright for a second or two, then dim, perhaps off. (this is the capacitors charging, then full)

As you increase the bias of the amp the bulb will glow brighter, and this is linear with the bias amount. A fully biased amp can get the bulb to glow very bright.

You cannot set full bias with the bulb in place - as it increases the bulb will glow more, limiting the voltage to the amp and all the readings will be wrong compared to when the bulb lead is out.

You can, however, set the initial bias with the bulb in place. Start the procedure, turn the pots until something happens, and set, at maximum, 0.1V across the source resistors and zero offset. Getting the pots started this way is a good idea. Remember, this is with a reduced voltage, and the pots will make the circuit draw MUCH more bias when the normal mains lead in used. Expect to measure 0.2V or more with a normal cord.

Hello Everyone from Florida!
My name is Eugene, I enjoy building musical gear (like the 18W Marshal guitar amp clone below). Hope to find some new ideas here as well as some help with repairs.

My car amp for my subwoofer broke, and i am wanting to learn how to repair it. Not sure where to start with getting replacement transistors as it is so old, so i have come here for advice!

Today many run their DACs directly connected to their class-d amps. I do. Amps with several 100 watts output and over 10A amps out.

I would guess that the signal ground in these amps are not the cleanest one could see. And here comes my culprit... the delicate ground in DACs where both clock ground and Vref grounds are tied up to the dirty class-d ground. Probably not ideal.



Why not make the PWM signal interface (red marking) after the "C" optical and let the input part float compared to the output stage. The only harmful part left sharing ground would be the triangle generator.

I bet such a combo of DAC and amp would be quite better sounding... what do You think?

//

This is a thread with everything discussing PCM58, and excellent chip which deserves it's own forum.

I want to resume some of my findings right now after months of juggling with many iterations of this chip in single ended dacs from China.

I will post some %%% in front of information which I could verify almost 100% by trial and error, oscilloscope and signal analysis.

%%% the signal must be 44, 48, 88 khz 16 or preferably 24 bits to the AK4118 receiver or it generates digital noise in the audio band. I don't believe any degradation from using higher resolution recording to downsample as the jitter/noise is the major quality factor here.

%%% the dac can be adjusted with trimpots, MSB, to 4th bit. It is a cumbersome process which doesn't necessarily translate to better audio quality, it is IMO necessary for the MSB and second bit. But further is no need, as the music is so complex it drowns any improvements and other factors are more important.

%%% Like the TDA1541, I find that 4X OS is the best by far, and 18bits only no less no more.

%%% In such a DAC the fidelity of the rendering is very subjective and imo not the reason why one would use such a DAC. I found futile to compare recordings/source (in DeltaWave) to assess the quality of the rendition. I did some visual checks of the waveforms screenshots vs originals and there is no visual differences. Mostly, one should focus on what details can be heard, and how much secondary voices (and complexity) are standing on their own or drowned, and how well the audible speech is rendered (are 'Rrrrs' realistic, Fss), and finally how deep and accurate is the soundstage.

more to come. And possible comparisons with PCM1701.

I just finished doing a writeup of how to repair PSB Image tweeters. I haven't found any information on the internet on this topic, but there is floating around many recommendations for a third party tweeter which I do not think is a great match. In the hope that this information is useful to someone I'll leave a link to my blog/whatever:
PSB Image tweeter repair guide

(Updated due to miss information on drivers). Good Evening. I have up for sale a Nice pair of Seas Coaxial Units from the 1990’s I think model T17-(H823) with crossovers for sale. They both work and preform as they should. Pulled them from a pair of speaker Cabinets. The drivers have no damage or issues or does the tweeters. The frames have some of the black finish chipped off because I had a hard time getting them out of the routed hole they were in. They are shielded and are not new but, Lightly used. I have no idea the price they costed brand new? Here are some pictures of them and the crossovers. Am just throwing in the crossovers and not asking for them in the price. 1 crossover is broken in half but, you can make a new board and solder them point to point like the intact one. Am asking for decent offers and not low end offers. Buyer will have to pay shipping to the 48 United States only. You can P.M. Me or E mail me. Thanks Jeff

Hello!

I got a faulty bass combo amplifier MarkBass Little Mark 250. But it appears to be a little more complicated than those I worked with before.
In general, I'm at a dead end, hoping for help from experienced forum members.

Symptoms:
The midpoint between the output darlingtons floats at idle relative to the ground (in the negative direction), when the difference reaches about 1V, the DC protection circuit is triggered and turns off the speaker.

While the amplifier is cold, it floats a lot. As it heats up, it stabilizes (it heats up decently, up to 60-70C degrees at idle) and works normally for a long time. Only sometimes the relay clicks for a second.

All supply voltages are normal, I unsoldered all the electrolytics, ESR is normal, does not show leaks...

Where to dig next?

How is this middle point adjusted there?

The purpose of some parts is a complete mystery to me, such as T3, T4, T6 for example...

I've drawn the schematic of the amplifier part of the combo:

Thought I'd see what people think about a little two way I've made before spending money on crossover components. Nothing too special, a Dayton DSA 135 woofer and SB26 STCN tweeter. I assumed there would be a dispersion mismatch and there is. There is also a notch in the DI at 350hz that I'm unsure of it's cause. Speaker was measured outdoors on a 10ft ladder. I have plenty of experience with active filtering but wanted to try passive for various reasons, one being to verify my measurement process.





Reverse null

ACA Mini is a very interesting amplifier.
It is Nelson Pass typical minimalistic.

ACA Mini works well with dual supply, +/-12V.

But watch out for the DC offset on the output.
Adjust before you attach your speaker.

Don't mind those components I have replaced.
It would work with the original parts.

Please post your finding and keep the list clean 😎

Link
Driver used
Pics
Price
Where to buy
Polar plots
Experience, subjective observations etc.

DIY Waveguides are also OK of course 😉

I'm very new to the world of DIYAudio but hoping to build my own loudspeakers and maybe a Pass design amp. I've been intrigued with all that goes on here and hope to share more soon! Thank you!

i have the Mark Levinson No. 36 D/A Converter, but it not working,
"NO CODE" is displayed upon power-up. how to repair it? thanks!

Hi to all ,Iam Neno from Croatia ,lovin diy,audiophile from 1997

hello folks,
here is something i have been working on for some time.
I am willing to offer the pcbs as a group guy.
let me know if there is interest.
I will share a bom to GB subscribers, all mouser based, if GB goes ahead.
regards
Prasi

Edit 1: Group buy closed for THT PCBs, but still open for SMD PCBs. More info in the below link.
Group Buy List
group list qty_new - Google Sheets
Schematic SMD LT4320 rectifier LT4320 based active rectifier
Schematic THT LT4320 rectifier LT4320 based active rectifier
Schematic LT4320 CRC PSU PCB: LT4320 based active rectifier

Edit 2: Revision in prices. (price drop!)
LT4320 based active rectifier

Edit 3: GB closed for SMD PCBs. Only last 10 pairs of THT pcbs remain.

THT BOM BY MERLIN EL MAGOO LT4320 based active rectifier

EDIT 4: New GB for LT4320 based CRC PSU PCB Started..PCB's Produced and being shipped..-Completed and closed...
1. The Design: LT4320 based active rectifier
2. The PCB design: LT4320 based active rectifier
3. Physical PCB's: LT4320 based active rectifier
4. The BoM : LT4320 based active rectifier

EDIT 5: Group buy sign up has begun for modified SMD and THT rectifier boards with ENIG finish and earlier LT4320+CRC PSU PCBs. Please sign up at the below google sheet with your DIYA username and qty required against each pcb type.
LT4320 based active rectifier
Some 3D views of how the actual PCB assembly looks like
SMD: LT4320 based active rectifier
THT: LT4320 based active rectifier
CRC PSU PCB : LT4320 based active rectifier

EDIT 5: HAVE ALOOK AT PAGE 78 AND 79 FOR ALL PCB DESIGN IMAGES, SCHEMATICS AND 3-D MODELS AT ONE PLACE.

New/unused - High quality compact terminal cups with gold-plated binding posts, 8awg bare wire/spade/banana/dual banana

$3 each - 60 available
$80 for all 60 pcs.

same as: https://www.parts-express.com/Round-Speaker-Terminal-2-15-16-Gold-Binding-Post-260-283

Please see photos below. Shipping from PA 18951 - not incl. /$TBD, either USPS or Fedex. PayPal only.

Please see photos below. Shipping from PA 18951 - not incl. /$TBD, either USPS or Fedex. PayPal only.

(Qty)
(2) Mundorf Supreme Silver/Oil 0.82uF 800VAC 1200VDC - $15 each (used, short leads)

(2) Duelund VSF stacked Cu foil 2.2uF no voltage rating - $25 each (used, full length leads) SOLD

(2) Russian Teflon FT-3 0.22uF 600V - $12 each SOLD

(2) ClarityCap MR 3.3uF 630V - $18 each (NOS/new) SOLD

(4) ClarityCap ESA 4.7uF 630V - $6 each, $20 for all 4 (NOS/new) SOLD

(3) ClarityCap ESA 1uF 630V - $5 each, $12 for all 3 (NOS/new)

(2) ClarityCap ESA 0.1uF/100nF 630V - $4 each (NOS/new)

(4 left) ClarityCap SA 3.9uF 630V - $4 each, $12 for all 4 (NOS/new)

(2/2/2/2/2) ClarityCap DTAC 630V M8 screw mount 2uF/2.7uF/3.3uF/4uF/4.7uF - $10 each or $60 for all 10 (used)

Thanks for looking! Make an offer for all if you like...

[SOLD] CSA 3uf 250v x2, 4.7uf 250V x2 capacitors, used for testing
$35, free shipping

Hi,
I'm interested in purchasing some audio item in Italy but i would like some help from some fellow italian member:
Item is on 'Subito' and being outside the country i can't register ( afaik), so i'm unable to contact seller to know more about the deal ( not even talking how good i'm in talking Italian...).

Please contact by pm if willing to help me to get in touch with seller.
Thanks in advance

Hi there,

I have a Phillips Cassette Player with a broken motor. I am looking for somewhere in the United States or Europe to get this fixed.

Type: EL 3302A/15G
Voltage: 7.5V
Frequency: 50/60 Hz
Manufacturer: Philips
Motor markings: WR 01 941


I believe that the motor I am looking for is a small DC motor, likely a 7.5V brushed type used to drive the capstan and reels.

Does anyone have any advice to where I can find one of these and/or get this fixed? I am located in California, but again, can send it anywhere.

Thank you.

I will post the availability and price of the 3 Way DSP Amp boards here.



Read more about the boards here.
https://www.diyaudio.com/community/threads/3-way-dsp-amp.415065/#post-7734899


The price of one 3 Way DSP Amp board is $95.

The price of one I/O board is $15.

Delivery to Europe and America is at my expense. Delivery to islands or other distant places is negotiated separately.

Order more than one 3 Way DSP Amp board and get $5 off.

Payment via Payoneer.


We currently have four 3 Way DSP Amp boards and four I/O boards with ESP32 available.

In my search for a monster open baffle woofer I stumbled the W21 21" open baffle woofer. It looks interesting but the more I research Lii Audio the more something seems off. I cannot find much objective information on them. Most of the people talking about them seem to have conflicts of interest. Then I found there are more than one version of this driver....some may even be copies or made by another company?

The driver on Alliexpress looks very different from the one for sale on lii-audio.com website.

The first one seems to have a single voice coil, the latter double. The first one has a lowish QTS of 0.39 and MMS 201g while the other one sports QTS 0.82 and MMS 644g.

Normally I would assume the Alliexpress is fake but then I read this by caisson rj:

I am happy to see some people talking about Lii Audio Xizi founded in 2006 and Lii Song founded in 2016 which is a copy of the original Lii Audio. I visited both headquarter in Hangzhou and it was clear to know which one fake it. If you hold both speakers in hands it's is really obvious. The short story is that Xizi Lii Audio hired one guy to expand the business outside china and that guys screwed him and founded Lii Song and took the foreign market. There is currently quite a lot of new drivers made by Lii Audio that are coaxial drivers that are simply harder to copy for Lii Song so in the future you will see more and more drivers that Lii Audio will only sell. I am talking 21 inches coaxial stuff, premium range etc.

CAN SOMEONE SET THE RECORD STREIGHT? SHOULD I BOTHER WITH ANY OF THESE DRIVERS?

ALSO...IS A 21" DRIVER WITH A 201g MMS even realistic?

https://www.aliexpress.com/i/1005003529835421.html

https://www.lii-audio.com/product/w21/

Does anyone have experience with any of the Lii audio/Lii Song 15/18/21" woofers?

I have a problem with an ML-9 amplifier channel, and I need advice. One channel works fine, but the other doesn't. I have disconnected all output transistors, and although I am able to see an amplified input signal at the output of the second amplification stage (the input to the 7-diode array), the DC offset at that point should be about +2.25 volts; instead, it's 420mv. The voltage across the 7-diode array is 4.53 volts (0.42 volts at the top of the array and -4.11 at the bottom, for a total voltage drop of 4.53.) Because the DC offset is almost 2 volts more negative than it should be, the pre-amplified signal saturates when the input voltage level is increased beyond about 100 mv. So far, I have not been able to determine why the DC offset across the diode array is 2 volts more negative than it should be.

I bought this amp for a really great price because someone before me unsuccessfully tried to find the problem; several parts were replaced. As a result, there may be more than one problem layered on top of the original problem. I don't mind clipping component leads or circuit board etches, but removing transistors will be a last resort, given the difficulty of desoldering these components. I have lots of voltage measurements, and I'm happy to take more measurements or replace some of the components.

Thanks for your help.

As some of us quickly learned from this thread that Lii Audio (established in 2006) is not Lii Song (established in 2019) now it's easy to define the original manufacturer by a line of brand new Coaxial Drivers.

As a fan boy of Tannoy I'm glad the Lii Audio (not Lii Song) is now making not only full-range, but new BIG Coaxial Drivers.

In this thread I want to discuss their new line, please do not post here about Lii Song as they have been separated from each other due to war between two ex partners. This is why you will not find coax drivers in the Lii Song catalog.

I hope Lii Audio will continue manufacturing unique drivers and will be able to expand their sales internationally, at the moment you can follow them on instagram for updates.

If some of you will find any reviews or have personal experience with any of Lii Audio COAX drivers please post in this thread.

On Ali Express for international buyers at the moment I can see '12 inch (C1202) , also '15 inch (H1502) and even '18 inch (Lii Audio TRIAX 18 and C1802) models and they are working on a bigger size as you can read on instargam page.

Some of them are good looking units, but pricey! What about sound quality?

Hello everyone.🙂

This is the first thread I have opened here with the aim to share my experiences with you and to broaden my knowledge about electronics from possible replies.

Over the 2020/2021 winter I have built an amplifier based on A60+ boards from eBay and was quite satisfied with the result: an amplifier sounds great, is relatively easy to build and involves everything what is needed to complete the project: power supply and effective speaker protection.

Below is a photo of one channel of the amplifier.

The amplifier comes in two different versions:
A60, smaller, with 3 output pairs of transistors
A60+, larger, with 8 pairs of output transistors.

There are variety of possible versions: with different output transistors
MJL3281A/MJL1302A
2SA1943/2SC5200

It is also possible to purchase bare boards, partially stuffed boards, complete boards and also amplifiers in chassis.

In addition to this the board incorporates a solid power supply and effective speaker protection. You only have to add your heat sinks large enough, transformers, transistors and capacitors.

I have decided initially for a A60+ version without output transistors and without power supply capacitors.

I also have tested A60+ and it sounds splendid indeed. Someone else on internet said its sound is "golden" and has gone that far to state that it has "euphoric tone". He is right it really sounds extraordinary. Just read this review.

I have also done extensive measurements: it measures great. It is done right across the whole audio spectrum and beyond. I will repeat the measurements and make them soon public.

The sound was great so I have decided to spend a bit more of time and money on this project.

I have purchased two A60+ and three smaller A60. This will be my spring 2021 project.

Finally, some hints for these who decide to build this amplifier:

Only capacitors with diameter 35mm and 10mm lead spacing will fit into this board. Initially I was afraid that just 4X10.000uF per channel wouldn't be enough, but it works indeed very well.

Carefully with biasing – this is a wild beast and can quickly go incredibly hot.

Chose heat sinks large enough to have freedom to set higher bias.

Just stumbled upon the site from Kvålsvoll Design, and their Compact Subwoofer Horns.
https://www.kvalsvoll.com/Articles/CompactSubwooferTechnology.htm

Looks like very solid engineering.
Getting 110 dB @20 Hz from a 70 liter horn box. Not bad at all!

They are employing tuned "pipes" to dampen resonances, e.g. see the insides of the T140.

Like the shape of e.g. the V6, which would make a very good pedestal og lower part of a 3 way, with the V6 + say a 6.6-8 inch mid and a horn tweeter!

Hi everyone,

I'm sam levy, and I'm diving into my first serious DIY project I found at a flea market. I’ve been lurking for a while, absorbing all the wisdom here, and now I’m ready to get my hands dirty.
Big thanks in advance for your patience and expertise—this community is a goldmine!

Hi, new on here. Would love to know a ton of information on tv headphones or tv speakers.,

I’m a sound engineer, musician and general tinkerer. Have a fairly basic knowledge of audio electronics. Currently in the process of restoring some Spendor BC1As. Will likely be pecking all your heads as I’m struggling with the inbuilt amplifiers.

Old school at the limit, inspired by the CD thread, a standard amp of the last millennium flowed from my fingers ... a kind of Santa Claus surprise today!



36 Peak Watts at 8 Ohm



Current Dumper without dump, only NFB.



TIP3055, BD139, BD140, BC5xx ... thats all we need.





Happy DIY,
HBt.

Hi all,

New and unused selected/matched (see attachment) Lateral MOSFETs bought from Profusion:

Single die, 200 V, 8 A, 125 W:

4 x ECX10N20 (Green dot)
4 x ECX10P20 (Red dot)

Double die, 200 V, 16 A, 250 W:

1 x ECW20N20 (Yellow dot)
1 x ECW20P20 (Yellow dot)

Sale price is 85 euros + shipping.

Regards,
VS

I picked up a TA-5650 in good to very good cosmetic condition that played music in both channels, but typical scratchiness turning the volume pot. I figured this piece is definitely worth a full dose of TLC to restore it.

• All the VFETS were pulled and tested - All good here
• Power supply board recapped and D405 series diode mod installed.
• EQ amp, selector, tone control and filter boards recapped and all switches and pots cleaned and lubed (where needed).
• All solder joints reflowed and pcb's thoroughly cleaned and flux residue removed. They were pretty messy from Sony, especially the amplifier board.

Still in the process of working on the main amp board. So far it's been recapped, death diodes replaced and some resistors swapped.

This is a good time to formulate a plan to replace the OEM speaker spring clips with 5-way binding posts. BUT, the puny 22ga hookup wire is driving me crazy!
I plan on replacing the output relay and main filter caps.... While the chassis is open, should I take this opportunity and rewire the full output path from amp board -->output board -->binding posts with 18ga flexible silicone jacket wire?

Or should I suppress the urge to replace the 22ga and move on.... 🙂

Thank you to Kimmo Saunisto for this wonderfull software😛, very very gratefull.
it is very complete and powerfull, but you need to know well loudspeaker design.
Software

thank you again.

This is a simple all Symmetric Class AB amplifier.
Distortion is low: THD 0.00045% at 1 Watt into 8 Ohm.
The VAS is a differential stage to increase the gain.
Output is simply EXICON lateral MOSFET.
Max like 15 Watt at +/-20 Volt supply.
Can of course use higher supply with higher output power.

I was contemplating building a linestage based on the ARC Ref 6 or later but I cant find anything anywhere regarding it. Does anyone have any intel? I spent some time trying to decipher pics of the PCB online and it looks like it is similar to the ref 3 but implemented a current sink on the CF along with some regulator upgrades. To be honest it seems like each new iteration from ARC moves closer and closer to Allen Wrights designs but with the 6h30 tubes.

Interesting original 6CG7 FIVRE . This marked FIVRE an high quality italian tube maker of the 70s. However, the 6CG7 (and other models) where produced by General Electric in the US and rebranded for the Italian market. I bought this tube NOS, I tested but then I never had the chance to use it in a line stage as I wanted.

I ask 35€ plus shipping from Italy

Excellent Dayton DSP-408 digital signal processor, complete with the DSP-BT4.0 USB Bluetooth dongle. Suitable for both car audio and home hi-fi use. I personally used it only in a hi-fi setup, and only lightly.

The analog outputs are of very good and can drive virtually any system. Output levels are strong and clean. It features a master input volume, and input/output levels can be adjusted independently. Supports crossover filters from 6 to 24 dB/octave and includes a 10-band equalizer, with fully configurable center frequencies and Q factor for each of the 8 outputs. I actually preferred it over the more popular miniDSP.

The DSP-BT4.0 Bluetooth receiver allows remote control of the unit via Android or iOS apps. Alternatively, it can be managed from a PC using the official app available on the manufacturer’s website.

The unit is used but in excellent condition. Sold exactly as shown in the pictures.

Price 170€, the buyer pays is favorite shipping service of choice.

For my American friends, the price might seem a bit high — but here in Europe, between import duties and taxes, getting the full setup ends up costing around €300.

I am only able to get the amp out of protect mode once I lift Q04. At that point I get audio on the class a/b side. On the class d side I get audio but it’s low. I do have full rail to rail oscillation.

Antek Transformer AS-05T320, 50VA 320V-300V-0V & 6.3V 2A x2 AS-05T320, never, $33 free shipping

Hi guys, as tittle said "Building BA-3 as analog output stage of noDac", well the noDac outputs 0,19Vrms so I was looking for something with a gain x10 to get near the standard 2Vrms, helping me to take the BA-3 option because I own original SK170BL, SJ74BL, K2013 & J313 from when I used Erno Borbely stuff, also it's not complicated to do it and adjust (very similar to Borbely), don't take to much room inside noDac box and is a lot of more easy and a lot of less money than make a DHT 4P1L with the same gain of course I don't expect the same SQ.

I read with attention NP BA-3 article, it seems with standard resistors values BA-3 fits nicely the x10 gain I'm looking for.

Attached NP BA-3 article to know if it's the latest or there is other new and also B.O.M. for a balanced unit that I will not do because all my system is SE.

I read Jfets have to be "matched if possible" at 10mA Idss, I have on hand:

SK170BL
9.48mA x 2

SJ74BL
9.02mA x 1
9.03mA x 1
or
10.11mA x 1
10.24mA x 1
What's best pair to use with the SK170BL?

I guess with these values P1 & P2 will remain 500R, right?

With the input voltage of +-25V can reach the x10 gain?

I will post pics of my work in progress.

TIA
Felipe

N.B. Big thanks to Jim aka 6L6 to give me a couple of PCB.

Hi All,

I have a stock of new transistores for sale:

130 -> 110 -> 55 x KSA1381E (Fairchild/On Semi)

130 -> 118 x KSC3503D (Fairchild/On Semi)

100 -> 80 -> 24 x KSC3503E (Fairchild/On Semi)

300 V / 0.1 A / 7 W / TO-126 / (grades D and E, hFE = 60-120 and 100-200).

Offers accepted for the whole lot.

Price per pair with a minimum qty of 20 pieces: 1.5 Euros/pair + Shipping.

For matching please PM.

Regards,
VS

Well... Here goes nothing!

I've been reluctant to do this out of fear of ridicule. You see, I'm not a very experienced designer and the design I'm about to present is a pretty mundane Class AB job.

But lately I've seen beginners on various forums struggle with designs that require exotic and/or obsolete components or designs that require very stable power supplies and careful thermal management. I've also seen people having a tough time with what's clearly outdated or outright bad designs that are floating around. So based on that, I thought a fellow beginner might find this thread useful.

I decided to share a decent amplifier that can be built using cheap components that are readily available from almost any source. It uses only 2N5551/5401, BD139 and IRFP(9)240 transistors, some 1N4148 diodes, a couple of 5V zeners and a smattering of capacitors and resistors. That's it! It runs fairly cool, does fantastic with a modest 40mA bias current and has a net negative temperature coefficient with regard to bias if you're careful with the thermal transfer between the VBE multiplier and the output MOSFETs. It physical tests, it's fairly flat past 100kHz at 50% power and gets a decent 0.003% THD at 80% power and 1kHz in simulations. I don't have the equipment to measure an accurate physical THD, but just eyeballing it on the scope, it's definitely <0.1% and probably a lot less. Nothing compared to the Class A masterpieces some people here are building, but enough to sound pretty nice. The way it's drawn it should be good up to 50W with the right heatsink.

It's also very forgiving in terms of component values and (probably) layout. I've messed around in SPICE, and it takes real work to make it misbehave. You can even mess up the matching of the LTP transistors quite badly without it throwing a fit. It also has a >70 degree phase margin in simulations and would probably do fine with a lower Miller capacitance if someone wants faster performance. I've tried it with 8ohm and 6ohm speakers, and based on simulations it should have no problem at all with 4ohm as long as you're staying within a reasonable power (50W). The gain is 23x (27dB), which is a bit low for regular line level. You could probably bump it up a bit, but I'd probably recommend a pre-amp instead. I haven't checked the stability with a higher gain.

This design has been built and sounds and measures well. Audiophile quality? Probably not, but good enough to "open up" music I've listened to many times before and letting me discover new details.

I'll share the schematic and also a Github repo with all the design and simulation files, along with some ideas on how to build and test it. If you're a beginner, feel free to try it or just borrow ideas and inspiration. And if you're an experienced designer, I'm happy to listen to ideas for improvement. You can even clone the repo and send me a pull request if you want to contribute. But please be gentle! 🙂

There are a few things I'd like to change when I get a chance. The pot on the long tail can be replaced with fixed resistors and the terminal block for the speakers on the middle of the board is awkward. But it's buildable and works well in its current form. You could (and probably should) add speaker protection and maybe a preamp and some tone controls.

The repo: https://github.com/prydin/classab-amp-mosfet

I hope you'll find my humble contribution valuable in some way. And be gentle on me!

[EDIT: Updated the schematic with a protection diode for the VAS to avoid disasters... Also removed the DC offset pot, since it doesn't do much due to the current mirror]

Hugh has been doodling on LTSpice and he came up with something really extraordinary: a 43% efficient SE Class A amp that can drive 39w into an 8ohm load with the usual Aksa-approved harmonic profile and low phase shift. The amp uses only 6 bog-standard actives and employs the excellent Aksa Lender front end to drive what seems like standard complementary MOSFET output stage using the venerable and easy to find IRFP240 and IRFP9240 outputs. However, it is not a push-pull amp though, but operates in SE Class A with an active CCS controlled by a cleverly wired PNP CCS controller. Please note that this active CCS is no longer based on the Pass Aleph topology but a PNP-controlled P-channel with symmetric sense resistors. The amp should really be called an Aksa Lender Nirvana.

So we have 4x TO-92's, and two TO-247 MOSFETs. Together, with only a +/-27v supply, they combine to make 39w into 8ohms with a predicted 0.019% THD AT 12w, and of course, always dominant H2 and a monotonically decreasing higher order harmonics. Output impedance is predicted to be less than 50mOhm at 12w into 8ohms at 1kHz and DF is 160. Quite a powerful amp given the rather low 27v rails. 27v rails happen to be what you get when you use an SLB PSU with a 22v trafo like an Antek AS-3222. Gain is 28.5dB, and phase shift is only 5.3deg at 20kHz.

Here is the rough schematic from LTSpice:


More detailed analyses and sims to come...

Later to be followed with the usual P2P vero-build, and then hopefully, a real PCB verification build and full measurements.

Enjoy!

A huge thank you to Hugh for continuing to give us these gems!

Edit Sept 21, 2023: Looking for Cliffs Notes on the BOM and some and hints on what parts to use etc by Voiceofposeidon here: https://www.diyaudio.com/community/...8ohm-class-a-amp.344540/page-107#post-6920076

Edit May 25, 2020: detailed O-scope max power clipping tests by AndyR using his 4-ohm variant Alpha Nirvana with +/-21v rails:
Alpha Nirvana 39w 8ohm Class A Amp

Short story - good for 34W into 2.1ohms loads! Not bad for true Class A amp (cannot ever go into Class AB - it simply softly clips when pushed).

Edit Oct 31, 2019: latest version 2 schematic of amp


Predicted FFT with v2 for 2.83Vrms into 8ohm, THD=0.0039%:


And if we increase power to about 12.5w into 8ohm, we still see a nice monotonically decreasing harmonic distortion profile. THD is now about 0.016%:


Edit Nov 27, 2019: Measured max output before clipping is 51.6vpp into 8ohms, or about 41.6w into 8ohms. This is with +/-28.5v rails.









Edit Nov 29, 2019 - Grounding scheme schematic (post 279):


Produces background noise FFT like this:


Some measurements at 3.16vrms into 10ohms with a Cayin N3 DAP as 1kHz osc source, obtained 0.0041% THD and mostly 2nd and 3rd harmonic:


GB thread for this amp here:
Alpha Nirvana 39W SE Class A Amplifier GB

Tips and tools on how to do professional clean looking SMT/SMD soldering:
Alpha Nirvana 39w 8ohm Class A Amp

Edit Dec 14, 2019: BOM in easy to read .XLSX format: https://www.diyaudio.com/forums/att...8ohm-class-amp-alpha-nirvana_bom_001-xlsx-zip
Mouser Shopping Cart for BOM here. Do not modify cart - please save to your own shopping cart as a new project before changing.

Edit Jan. 3, 2020: please note that the Mouser shopping cart above needs to have parts for snubber boards increased by 2x as there are parts for 1 board only. The BOM is for one amp board so needs to be doubled for stereo. Double following: (R1001, R1002, C1002, V1001)

Edit Dec 26, 2019: AndyR did a lot of due dilligence to put together a very nice BOM for both the 8ohm and 4ohm versions of this amp here:
Alpha Nirvana 39w 8ohm Class A Amp
Thank you, AndyR!

Edit Apr 24, 2020 - Dual Monobloc Connection Diagram is using SLB and SFP boards:


As built schematic verified and tested to work:


Edit Apr 19, 2022: beautiful build by Steve (Sledwards12375):


Edit July 12, 2024: @AKSA said in this post that 2.2A quiescent current is needed for 4ohm variant of this amp. So size your trafo accordingly.

Finally got the chance to see it. Thoroughly enjoyed it. Go see it folks.

After Sean Bakers “Red Rocket (2021)” again a modern fairytale at the wrong side of society. Recommended!

https://m.imdb.com/title/tt28607951/

GE & Sumitomo metals - Invented Neodymium magnets. World over there is a shortage in supplies. Must be sad for the inventing engineers & scientists to see that in 43 years their own countries do not have adequate access.

I wanted to share here my experience of building the Mark Audio Okapi with Alpair 7MS designed by Scott Lindgren. I was looking for a relatively compact (i.e. narrow) loudspeaker that I could use in my home office. The plan is to use it with an Audio Note Kits "Virtuoso" PP EL84 Headphone/Speaker amplifier that I built a few years ago. I am currently using a pair of Fostex FE83sol in tiny cabinets and I wanted to see if I could do better than that. After reading many posts in this forum I decided to give a self build a go.

Since I do not have a workshop I ordered my plywood (18mm baltic birch) pre-cut online from cutmy.co.uk. I could even specify the circular cut-outs for the drivers and the reflex tube. Here is what came in the package:

Hi,

I have been away from DIY for a wile. Used to use the light brown colour Dale Metal film resistors in the past which were decent at reasonable price.

Recently, I want to build a simple 3-ways Analogue Signal Processor. Bought Some Dale CMF55 1/2 w resistors from Mouser and Digikey. However, three of the many values got are in light blue and are made in CZ republic ( the other values I got are all light brown made in USA same as those I used years ago).

I used a magnet to test the light blue CZ made one and found out that they are magnet attracted to magnet ( possible at the end caps).

I want to get the light brown ones which are non magnetic. So, I buy the three values again from Digikey. I enquired Digikey before I place the order to ensure that the three types ( values) I selected are made in the USA. However, once I receive them , still, one of the three values I got is in light blue made in CZ with same magnetic properties. They are near the same manufacturer code number.

I am too frustrated and not sure how I can get the light brown ones. Emailed Digikey but received no response.

Not sure if fellow DIYers have similar experience. Whether the RN60 versions are still made in the USA in light brown and are non magnetic? If they are, I will pay a bit more to get the RN60 versions.

Appreciate if you could share your experience or information.

Thank you very much

Would anyone have a Dynakit z565 output transformer, either a new or a used one in good electrical condition that you would be willing to sell?

People keep talking too much about jitter issues, but did less to make some kind of improvement. I decided trying to do something real – a working asynchronous I2S FIFO.

Before I go any further, I need to make something clear in advance:

1. FIFO is widely believed as one of the final methods to deal with jitter problems. But the asynchronous FIFO itself is just a technology which could provide a logic function to isolate the two clock domain. That means, for an I2S stream, digital audio data could pass through without any modification but the input clock was blocked and replaced with the new one. The new clock is totally independent from the old one except they should have the similar frequency. The FIFO logic itself does not influence the sound quality;

2. What really makes it sound better (or even worse) is the low jitter secondary clock. For example, if we have a new clock after the FIFO which comes with one digit ps jitter(RMS), we should get much better sound quality than before (the jitter level of the master clock from DIR chip usually around 50ps(RMS) level above corner frequency). So, we should pay more attention on the secondary clock and related interface. Everything connected to secondary clock has to be very carefully to deal with; otherwise new additive jitter will be introduced;

3. The size of the FIFO memory should big enough to meet overflow or empty time caused by the worst case of i2s input clock, but still has to be carefully selected to get the balance between the delay time caused by the working depth(usually half full) of the FIFO;

4. FIFO with low jitter secondary clock could only reduce the play back jitter for an audio DAC, but has nothing to do with the sampling jitter. I don’t have any idea if a CD was reordered with poor clock of the ADC.


The main logic functions could be achieved by a FPGA/CPLD chip together with a megabit SRAM. But the clock section has to use specialized clock/timing circuit, because the jitter performance of the output of FPGA/CPLD are far from what we want.

Below is the possible block diagram of this I2S FIFO project:
https://github.com/iancanada/DocumentDownload
https://twitter.com/iancanadaTT

FifoPi Q7 Jan.12,2023 update https://github.com/iancanada/DocumentDownload/blob/master/FifoPi/FifoPiQ7/FifoPiQ7Manual.pdf
FifoPiQ7_0 by Ian, on Flickr

Greetings to everybody and thank you for letting me post my rather stupid questions. Hopefully I can contribute to the forum as I learn more.

I'm currently trying to build a stereo amp using a pair of Chinese JLH 1969 kits. At this point, I've stuffed a PCB from one of the kits, but I want to be sure of my power source before learning how to adjust/test the circuit. I don't want to fry anything. Despite plowing through loads of posts from various sources and watching Youtube, I still haven't found a simple step-by-step guide to building this amp.

Does anybody have a link to a set of basic instructions on how to build a kit like mine? Are there any instructions out there on how to build a basic power supply for this amp?

Is it okay to use a "wall wart" transformer that provides 12V dc from standard US household AC? If the "wall wart" is okay (even if just for adjusting/testing), what is a typical 12V current rate - 1A? 1.5A? 2A? I'm not trying to modify the amp circuit, so whatever voltage/current gets the "standard" performance is fine.

Thanks for any help. Again, I apologize for such basic questions.

Hi all!

I have an interesting hint here to this

https://ascilab.cafe24.com/shop2/company/about.html

https://audiosciencereview.com/forum/index.php?threads/ascilab-f6b-bookshelf-speaker-review.63387/

but i have no idea in which category to place

- Stefano

Hello,
I'm Ricky from Genova, Italy.
I've made my home hifi.

All I know is the following:
NPN, RCA, p/n 38110 TO-18

I was hoping someone could provide the specification!

Thanks.

Hello, I've had an account for some time, but now want to make it official so here I am.

Current projects: fixing/restoring console amplifiers with 7591, EL84, 6V6 tubes; all with 12AX7 drivers. This type of amplifier work are new to me.

Prior projects: type 27 battery biased line stage; SE parafeed 45 amplifier with c3g drivers; SE 2A3 parafeed with 12AT7 drivers; 6021 line stage; ecc88 preamplifier.

Possible future projects: SE 2A3 parafeed monoblocks; 6T9 amplifier (since I have the circuit board for it).

I've taken a break from amp building fornmany years and now I'm back.

Cheers!

I looked around and can't find a good place to file this thread, so if I missed something, Mods, please feel free to relocate.

I am about to purchase an Alesis BRC which will (hopefully) control my HD24 [24-track hard disc recorder]. It was originally designed to control many ADAT machines, daisy chained together. ADAT uses SVHS tape for audio recording. Anyway the HD24 is 24 tracks od digital recording onto hot-swappable hard drives. But since access is orders of magnitude faster on the HD than spooling tape, there can be sync issues... (it CAN allegedly daisy chain HD24s to provide 48+ tracks, up to 128 max or something silly like that)

I have the Alesis service manual, and it indicates an appendix for the schematics, but they are not there. It must have been a separate file or insert added at the repair facility. I do have the "confidential" service tech final testing procedures at the end of the copy of the manual I have so it seems to be "complete".

Please have a look around and see if you have one or can point me to an online source. I can't find it anywhere and I was digging pretty deep...

Thanks in advance for any help!

A couple days ago I measured a set of speakers (in-room). After a few minutes I repeated the measurement with the exact same settings (maybe apart from signal level and mic sensitivity), without changing the placement of mic and speakers. To my surprise both measurements were quite different. Today I repeated the process, and again, two measurements a couple minutes apart show very different results.



Measurement setup
Amp: Hypex NCore based (AudioPhonics MPA-S250NC)
Audio Interface: Behringer UMC22
Mic: Dayton EMM-6
Software: REW 5.31.3
Driver: ASIO4All 2.16

Today I loaned an Audio Interface from a friend of mine, a Focusrite Scarlett 8i6. I was hoping to eliminate this link in the chain. Below are a few measurements.



As can be seen, there's much less variance between these measurements. But still over 4dB, which seems way too much to me.

Has anyone else had issues with inconsistency in measurements?
What whould be the most likely cause?

I am selling 2 pairs of TW29TXN-B satoti tweeters.
Selling as i am moving to be tweeters
Looking to get $300 per pair
Buyer Pays shipping and paypal

Manufacturer😛ikatron
Type:Trennübertrager
Model:ÜB3091M
Transfer ratio:1:1
Input impedance:1 kΩ
Output impedance:1 kΩ
Frequency response:40Hz - 20 kHz± 1 dB
Distortion, f= 40 Hz, 2,5V:K3 ≤ 1 %
Condition:used, ok

Price15€/piece + postage in EU
50€/5pieces + postage in EU