Peavey, EV, Sunn (I think) all had these type with throat area ~= or >Sd, and horn depth only a few inches.

A friend who built the one below with PRV 10", compared it to a simple box.- Female listeners preferred the vocal projector to the plain sealed box.

Under what circumstances is this technique useful?

I'm looking for all the Audio Amateur issues from 1988

Recently I tested my Buffalo II DAC from Twistedpear - a 1kHz sine 0dB Test Tone.
There is a "squarelike" but faint distortion in the upper frequencies.
But before running a verdict, I should mention that the testtone is from 1982,
from an YEDS-18 Test disc made by Sony for service personnel.
I analysed the file in Audacity , one sample width shows clipping,
whereas 3 samples show no clipping.
No clue what the sample width practically means.
Assuming the sample is error free and spot on with full scale,
clipping needs at least two samples, because the resulting curve
between the two samples overshoots 0dB.
But the test tone on the YEDS 18 it was made while only 16bit ladder resistor DACs
were common, to my knowledge, clipping with them is more audible.
I analysed the file in Audacity , one sample width shows clipping,
whereas 3 samples show no clipping.

The 60 second sine testtone from the YEDS-18 is too big to be attached.
So here is a downloadlink from Wetransfer, it is valid for 7 days:

WeTransfer

Would be interesting to hear whether the fault is a test-signal from the dawn
of the Digital Age, or DACs that spoil a signal with no headroom while upsampling...

EDIT: Audacity also has a tone generator. The generated sinetone made by Audacity also "clips"
when being analysed with one sample of distance.
So this analyse tool seems to be useless or a 1KHz Tone at full scale clips by default,
as there are overshoots between samples...?

Working on rebuilding an 800.2 completely. I’m stuck on the drive circuit. I have no output to the gate pins. I’ve replaced TL494C with a new one also replaced all four smt 2A / 1A. There’s no voltage present at the gates.

https://www.hificollective.co.uk/sites/default/files/mdt-33-datasheet.pdf

Morel MDT33 -legend MADE IN ENGLAND
condition close to new
i have 2 pair this one used once for test
sound very close to beryllium tweeter sound
clear and crisp

box and all pack original condition

400$US pair



These tweeters represent the finest in soft dome tweeter construction. Features a treated 1-1/8" soft dome, ferro fluid cooled aluminum voice coil, and double magnet system that is vented into a damped rear chamber for exceptional power handling and exceedingly low distortion.

Specification:

Znom 8 ohm
Re 5.2 ohm
Le@1kHz 0.09 mH
VC height: 2,7mm
Air gap height height: 2,5mm
Lineal coil travel: 0.2mm
fs 700 Hz
Mms 0.44 g
Sd 6.0 cm2
BL 6.3 N/A
VC Ø 28 mm
Sensitivity 1W / 1m 92.5 dB
Nom. power DIN 200 W
Weight 1.1 kg

pair SEAS Excel W26FX-001 (E0026-08S) 10" Aluminum Alloy Cone Woofer
price for 1 pair

Product Specifications
Manufacturer SEAS EXCEL
Speaker Type Aluminium Magnesium Cone Woofer
Nominal Diameter 27cm
Impedance 8 ohms
Power Handling (RMS) 150 W
Frequency Response 20 - 1000 Hz
Sensitivity 87 dB
Voice Coil Diameter 51mm

720$ US+ shipping + paypal fees
all in original packaging

For sail AUDIO TECHNOLOGY 18H521506SD midwoofer
Price for pair 475$+ shipping

Resonance frequency - fs:
40 Hz
Equivalent volume - Vas:
28,5 liter


Qms
1,8
Qes
0,39
Qts
0,32


Nominal impedance - Zn
8 ohm
DC resistance - re:
5,6 Ohm


Effective cone area - Sd:
137 cm2
Compliance – Cms:
1,09 mm/N
Mechanical resistance – Rms:
2,04 kg/s
Moving mass – mms:
14,6 g
Inductance 1 KHz – Le:
0,13mH
Force factor – Bl:
7,3 N/A


Winding height – Hc:
17 mm
Air gap height – Hg:
6 mm
Nominal power – Pn:
150 W


Acceleration factor:
499
Efficiency – SPL:
89 dB

Got this amp with blown power supply fets and driver transistors. Fets were IRFP064N. This amp was repaired earlier and technician had spoiled someone the vias of power supply driver board. I changed fets to 75344g and also gate resistors 51.1ohms. Amp coming on and producing good clean outputs. But power fets gets very hot at idle. And almost pulling 2.1amps. Any suggestions?

Hi diy audio form,

Im imagining to build a subwoofer couch- a couch that can observe normal couch functions, but also be a capable deep reaching subwoofer when i need to throw big party in my house or to suprise people.
background:

• Ive built sealed and ported boxes before, 18 and 15 inch woofers for permanent pa system, designed coverage for specific rooms. but i want to go wilder-
• i have access to a cnc machine, and lots of cheap good MDF. subwoofer design dream, i know-
• I dont have a problem with a complex internal structure of the couch / bracing. I can build box.
• I dont give a thought about size or weight. this thing could be 600lbs.
• I'm not religious, I dont give thought about adhere to audio dogma. I want this design to be unorthodox, I don't care if it's not perfect. I want it to be loud, still good sounding, and be an interesting talking point for guests as well as able to run the dance floor.

So, my idea is that I don't want the woofers visible, both to protect them from damage and I don't like the look of metal mesh / grates over the drivers. just a personal issue sorry. I already have an 18 inch eminence impero i want to use for this, and then I want to get a 21" as ive never used one before. The idea I have is to have the couch split into two separate subs internally, intimately crossed together. I'm thinking the 21" to cover 18hz to 40 or so, and then the 18" section to cover 40 to 90 or higher. Since the subs are enclosed in the couch, and these are such narrow bands that I only need, want to take advantage of the situation and do them 4th order or 6th order bandpass to make it earthshaking. I'm thinking the space under the arm rests could be big vertial ports on each side, the left side for the 21" and the right side for the 18". What if this could also create some interesting phantom stereo bass action with the different frequencies coming from each port. Again, don't care about perfection. Want interesting.

SO, just putting this here to get people thoughts on this, 4th order or 6th order, or other configs for the two woofers in the couch. Anything you want to say. Love speaker building 😛

Got a Revox B790, no power when plug in. Power board had a Cap that was shorted and broken power switch. Repaired power switch, Rebuilt power board( caps, thermistors, bridge rectifiers, and regulators), recapped all electrolytics on other boards. TT now turns on, digital LEDs light, motor spins, arm moves, cartridge raises and lowers. Voltage from Power board appear in spec. Great, but here are the problems:
1. When first turn on, motor turns on briefly then stops, even before the tracking arm is moved into position
2. The LED display turns off when arm is moved into tracking position.thus no reading of rpm is possible
3. the motor has a clicking sound ( when motor is manually spun (not turn on) no clicking/ noise noted

I really like the quality of the stores "blue" circuit boards, eg. The Universal Power Supply board. Can someone tell me who the manufacturer is and what thickness the copper is? Those boards withstand repeated soldering/desoldering really well. Thanks in advance.

Please help. I have a MRX-130. It worked on the AUX, and Phone settings. LEDs on the buttons lit up. FM and AM did not work, no sound at all, the Display showed zero. I purchased kits from Les (Circuitsandconcepts) and installed new caps on the main board, Les' regulator, and a new Trip Cap in the sandwich stack for the display. I installed all and triple checked the solder for errors. When I powered it up with input to the AUX it sounded great and the power on light at the bottom of the display lite up. However, now I had no display at all and the selection button leds are not lite. I can not change to any other inputs. I have triple checked all solder, I have checked with my in-circuit tester all caps. I went to "thecarversite" and have not found anything that can help me. I checked a few voltages:

On the Preamp, TC9152
Pin 24: +14.7V
Pin 12 : – 15.0V
On the tuner TC9147 pins.
Pin 42 and 41: 5v
Pin 34 and 35: 1.802V

I do not want to trash bin this receiver. I restored one a year ago and it was really nice. Any suggestions would be greatly appreciated.

Hello
This is my fist time doing a post so hope i am doing correctly and in the correct place. See correspondence from a Teck. i have used for years that is suggesting i get someone with experience with these amps to look at it .He did the usual things that old amps. need but then ran into this issue below .My problem is that Georgetown [ if one was interested in looking at it ] is along way from Ottawa and this amp. is heavy to ship.
Any suggestions
Cheers

"Hi David,

Further research on possible causes of the observed power supply issues suggested that the transistor Q1 (MPSA93) might be faulty (it is close to the part of the board which had the overheating resistors). However, replacing the MPSA93 did not solve the intermittent power supply issues.

The Carver M1.5 does not use a typical linear power supply; it has a "tracking" power supply that varies the B+ and B- rails to follow the input music signal. Although reputed to be an excellent design, troubleshooting faults is a complicated process (see pages 18-21 of the attached service manual). The problem may very well be with the leaky/failing dual capacitors (C13/C14) that I mentioned in my earlier message. And as discussed in the linked AK thread in the earlier message as well as the M1.5 Service Bulletin (included in Service Manual), their replacement requires an adapter board since dual can capacitors are no longer available. I do not know of any local source for the adapter board, but it is available from after-market sellers on eBay, e.g., https://www.ebay.com/itm/220766804156?hash=item3366ba18bc:g:GjcAAOSwUuFWxmds.

At this point, I think it would be best to have your unit looked at by a tech that is familiar with Carver amplifiers rather than me since I lack specific knowledge/experience with this type of design. I know of a former Carver Authorized Service Centre/Distributor with an excellent reputation that might be able to help; he is an Administrator at DIYAudio (https://www.diyaudio.com/community/members/anatech.12165/ ) and is located in Georgetown, ON."

Good morning,

For sale this Swiss tool 🙂 Phono, ADC, setup tool.....very handy.
From September 23
Updated
Paid 548$+VAT+CUSTOM....
Barely used,
SOLD
https://parksaudiollc.com/

Hi everyone. Im new here
I need a little help
Me and my father built a Pass Labs aleph 3 amp and the problem is that when we turn the volume up on the preamp, at the bass it distors a bit.
The question is what can we do with it
I atached some pictures of the amp if the problem is with the cables

Hello all, I haven't been here in awhile so sorry if this topic may have been talked about before.

I'm currently planning to a Jim Griffin's Line Array using the Dayton Audio DMA105-8 4" driver. I will be doing a Power Taper using his guide on the white paper to get 8 Ohms or slightly over. Now my question is even though these are Full Range speakers with 70Hz- 20Khz range, can I get away without a Crossover? I do have 2 Monolith THX 10" 500W subs to use in cause it does need lower end help.

I will be doing a 12 driver per side build. hopefully I will not need too much help in that part. I do have Xover Pro software to help if i do need a Xover to help this build.

Anything else I may need that I may be missing?

Hello,
I bought a bluetooth module based on QCC3034 chip bt module and I want to program it but I don't know the pinout of this board. Anyone can help?
Thanks!

I am currently measuring my subwoofer with dayton audio umm 6 mic. But in REW its doesn't show any low frequency spl & it show good spl from 150hz..
I m not getting wether it a fault of mic or software..
If any buddy know something about this please let me know.

Hi guys,

As you know, a lot of vintage woofers have paper surrounds, that get fragile or may have already started showing splits.

How do you revive or reinforce or make these compliant?

What do you use and how do you do it?

In good condition, with some mounting marks. Function perfectly, can provide impedance sweep data on request

325USD/300EUR/500AU for the pair + shipping. If interested let me know and I will enquire for shipping to your area. Cheer

.

Hi everyone, please help me with finding the schematics or the service manual for Cambridge Azur 840E preamp. Unfortunately, my beloved Cambridge Audio 840E preamp is broken.

Thank you in advance.

sanji99

I recently dug out my long forgotten sub I put up together sometime ago, so I decided to pair it up with my DIY bookshelf speakers based on w12cy001 + XT25 to see how this setup would work. Amazingly, it got me exactly where I wanted - very close, if not over the KEF Reference 3 overall. It's a 28l closed box with JBL CS1210 car woofer that I found on sale for 40eur. Now that I got my appetite for low end in the open, I'd like to see if I could upgrade it to something even better. I can't see what the Fs is for this woofer, but probably not too stellar. I do run it with FreeDSP into Sure Electronics 200W class D mono block so I can adjust and flat it out pretty well, but there are probably still limits on how low it could go. Would a switch to GRS 12SW-HE with Fs of 22Hz make any sense? I wouldn't mind going even for something substantially more expensive if that would make audible improvement, considering I am listening mostly at lower levels.

Putting this together now, but not open baffle due to aesthetics.
I can still change it at this point:

Will it sound like ****?​

Also when it's open baffle it's radiating surface is 104 cm^2 instead of 52 cm^2.
This GRS sounded fine open baffle crossed at 300 Hz on my table.
The Dayton RS52AN did not sound as good, especially in the low end, which was surprising to me.

Why does Zaph write this about the B&G neo3 :
"Note: these were tested with the rear chamber in place. Later, with a different pair, I also tested with the chamber removed. The tweeter was far too overdamped in that case, and I recommend leaving the rear chamber installed."
Why is overdamped bad?
Is GRS like this?
Marketing claims GRS PT6816-8 is for "open-baffle" "line array".

My enclosure is almost done.

SB Acoustics SB23CACS45-4 8" ceramic woofer- 4 ohms is also a great woofer​

SB is more for bass and build quality is really nice.
If you want 20 Hz to 1 KHz, it seems to be a good choice.
Seas has more detail and my metal grill fits over it.

I am looking for an ACA mini that works perfectly.
THANKS

HI,
I bought a drawing of a Yuichi A-290 horn.
I know that the best solution would be to mill it in wood with a CNC, but the cost is very high..
I tried 3D printing them and they don't look bad, but I'm not sure I set good printing parameters.
Can good results be achieved with 3D printing?
I was thinking of trying to print them again, empty inside, with 10 wall shells, and then pouring some plaster inside...
could this be a good idea?
the drivers are jbl 375 and the printer is a bambulab
Thanks and sorry for my English..

Discipline by King Crimson.. 40th anniversary cd set. Finely crafted music by very talented musicians.
https://www.amazon.com/dp/B005FMB8X6?psc=1&ref=ppx_yo2ov_dt_b_product_details
Interesting that as far as I can tell there are no synthesizers used by the musicians. Whether or not they were used during mastering is not known to me.

Hello everyone!

So since im not expierienced and im a little confused with some calculations i would like some help from someone expierienced. So im using the pt2314 audio proccessor and i want to calculate the max gain of the input signal to the power amplifiers.




So this is the datasheet of the part.

The max Input gain at 11.25 DB i got about 3.65 gain (Correct me if im wrong). So that means my max output amplification will be 3.65 times? Also at the volume control i dont really understand what the min/max attenuation rating is so if someone can help would be apreciated.

Moving on at the Max input signal handling at 2Vrms i got Vpk at 2.8 so that means that my maximum input signal i can handle is at 2.8 Vpeak? And if so i could get a Vo 2.8 * 3.65 at maximum gain?

Many years ago I built 2 LM3875 monp amps that have been going ever since. I have started using them with my Lampizator P-17 open baffles and they sound really good. However the input is getting saturated and I am getting some odd static type noise. I have 10dB attenuators and these have removed it,

The circuit is shown below. If I wanted to alter the input sensitivity would I change the value of the input resistir (56k) or is it not that simple.

http://www.decdun.me.uk/gainclone.html

Hi

I am looking for an inexpensive USB interface with an output that allows DIRECTLY connecting PCM56 PCM 58 and similar R2R DACs without glue-logic

I have I2SoverUSB JLSound for the main system but I'm looking for something cheaper

Hello together,
I want to change from 8ohm to 4 ohm has anybody an Idea how the wiring shoud be done for an 4ohm application ?

Cheers
salwa

Hi guys, I need schematic for an old preamp Yamaha PB1. Any help?
There is one old tread about it, but all links is broken.

Veneered all 4 sides of this cabinet yesterday, PPR, Platen, Cauls, and Clamps and it hurts to type this morning. Twisting/untwisting those handles at age 76 is killing me! 🙄

Golden years my ***


!

Is anyone familiar with the HYP-END from the German "Klang und Ton" about 1993, the Holger Stein kit?

Questo amplificatore mi è stato portato da un mio conoscente dopo averlo ritirato da un altro tecnico.
Fusibile F02 interrotto a causa di D08 in corto. Sostituito con 1N4007. Il relè dopo pochi secondi si attiva regolarmente nonostante vi siano 6v di offset! Niente audio in uscita. Ho tolto una scheda driver e comunque ritrovo i 6v di offset su entrambi i canali. Ho controllato tutti i componenti e sostituito diversi condensatori sulla scheda alimentazione e protezione senza successo. Grazie Anticipatamente a chi mi potrà aiutare

Hello everyone,
Will you please suggest may I replace a 5H filter inductor with a 1H Triad inductor ?
Thanks in advance for your help.

This came to mind since driver distortion has gotten more attention lately, in combination with more people (including me) moving to DSP-based active XO, so in many (some?) cases drivers are connected directly to amp outputs. Consequently mids and tweeters can see DC from the amps too.
I imagine it's a non-issue with woofers and 'normal' offset voltages that are within maybe 10mV range, since woofers have been DC-coupled for for a long time in passive crossovers, and it would likely have been mentioned and studied. I'm thinking tweeters and mids could be more sensitive though? Is there a reason to run a series cap on the tweeter more than for fault protection? Also, all amps are not equal, and some may have larger swings in DC offset with temperature etc.

Any insights are welcome! 🙂

I am getting confused about an issue my line stage is having.

The stage, easier to describe than picture probably: Elma input selector - Elma 100k stepped attenuator with 470k resistors parallel to the output - transformer coupled 6SN7 using Sowter 1367 transformers running at 200V, LED bias at 4.8V. Heaters are DC.

Recently, as the stage heats up it appears that a few volts DC is appearing on the input connectors and I am struggling to even think of a mechanism by which this would happen given that the attenuator and the parallel resistors should by definition reference pins 1 and 4 to ground.

I have replaced the valve socket, it is happening with either of the valves I have to hand.

Before I go completely bonkers, am I missing something obvious?

Hi,
I have a GAS Thoebe Preamp that needs repair on both phono outputs, as they suddenly stopped working. As my local repair shop is working to fixing this, we came across on a couple of more issues and we are in need of the following board schematics.

• gas-528c
• gas-333f
• gas522c

After some internet search I found a couple sches but non of the above. If someone can point me to a link or share with me the sches ill be grateful! I am very eager to repair this pre-amp, not only cos it's a great module but also due to its sentimental value.

Thanks in advance!

Hi yall!

I would like to add remote volume control to ye olde Logitech X-530 speakers.

This is the 10 kOhm 6 gang potentiometer

which is located on this board.


I think that the best way would be if I could control the volume by directly changing the resistance. I was looking for digital potentiometers and motorized ones, and also using a servo motor to directly rotate the knob. Since I'm new to audio electronics I'm not sure if there are any pitfalls or downsides by using any of those. Or maybe there is a different way to control volume?

I have a single Lowther A55 waiting for use but the question is somewhat generic - I've been looking around for inspiration and I see a lot of people have been happy putting a full range driver with whizzer cone into a front loaded horn. So I've been reading up on horn theory, and see how a front loaded horn works with a cone driver. But there's not much written about how a whizzer cone driver works in such a horn.
The popular tractrix profile, and other similar profiles usually require the horn to have quite some length in order to reproduce lower frequencies and this looks like a bad starting point to me for a whizzer cone as the high frequencies will be radiated into the walls of the throat and bounce around from there. Or the throat simply cuts off the higher frequencies altogether. I can see why some folk just cut off the whizzer cones and add a separate tweeter.
So it seems to me that only a shallow horn is practical if the whizzer cone h.f. sound is to be preserved. Then it's down to conical profiles for the most part, or oblate spheroid for better loading of the main cone.

Anybody looking into this ??

Working on tube emulation with transistors and want to compare with triode models.
I am assuming LTSpice is best source for models. I heard you can import LTSpice models into Simetrix

Where would I go to download the best models for standard preamp and low power class AB tubes?

Hooked on Simetrix - retired switchmode converter engineer and SIMPLIS/Simetrix common in that field

Hi, I have an old device in bad condition and I want to know what component this is. If it's an inductor, can you help me identify its type and find an equivalent to order?
Thanks All
t

I'm selling a pair of JBL 2431H compression drivers. These are neo drivers with aluminum diaphragms and a 1.5" exit.
They're used but in good working condition. Were originally for a JBL clone build, but have changed direction and have no use for these anymore.

Price drop, now asking AUD $250 for the pair.

Drivers are in Melbourne, Australia, so prefer local sale, but could negotiate shipment to a trusted buyer.

The 4.7 resistor that right behind the speaker terminal keeps burning up.I replace it and the series capacitor,no change.The channel plays good audio.


Any suggestions?

What is preferable; WMT or WTM horizontal driver arrangement?

I am buying components for a floor to ceiling open baffle line array. The array consists of 24x 12cm vintage alnico drivers supported by 8x 15" woofers and 36 dipole amt's. All first order crossovers at 300Hz and 3600Hz (not set in stone....start of voicing)

Before I start cutting wood I need to decide between WMT or WTM.

And after building I need to decide to place the speakers with woofers on the inside or outside.

Instinctively I would go with WMT TMW but I see many examples of people going for WTM. Anyone can point me to some pro's and con's of different arrangements?

Thanks!

Hi everyone. I am currently working on a Rockford Fosgate Punch 250m2. The Amp powers up and the right channel plays as it should. The left channel however, is having some issues. If I run the Amp below 11.8v, the left channel will play loud and clear. If I raise the input voltage above 11.8v, i am only able to get roughly 10 watts out of the left channel before it starts to distort very badly. However, under no load the left channel produces a clean sine wave at all input voltages. I can't seem to find any obviously dead components on the board, so I was curious if anyone else has ever seen a similar fault. Thank you.

Hi. I’m testing my stereo version of Pete Millett’s Engineer’s mono-block amp.

The power supply is different. Being stereo, it needs a much bigger power transformer for a start. It’s also higher voltage/power with regulators running at 525V. The differential input/drivers are 6EJ7s – higher gain than the original 6CB6s.

As in the original design, the 6HJ5 output tube heaters are AC-powered and elevated to 50V.

There’s no global feedback yet – just anode-to-anode feedback. Here’s a link to the original schematic.

Some 1kHz distortion plots look great. Like this one at 1W:



And this one at 2W



Others show 50Hz and 100Hz side-bands around the 1kHz fundamental without much 50Hz:



That's probably the worst one. Where are the 100Hz side-bands coming from?

Or with a lot of 50Hz. This is at 10W



What I’ve found is that this problem is worse with certain output tubes than others, and gets worse as the power level is increased.

My question is, am I seeing artifacts resulting from AC heating of the output tubes or should I be looking for something else?

Hi,

After nearly two decades my 808 SET is finally operational, with an experimental PSU:



Due to the unusually high Z plate load (5k), I'd like to keep the B+ as close to the 450V rating of the caps as possible but without severe voltare overshoot during startup.
I'm currently using a 310V toroid, 1300V SS diodes and a simpe CLC filter which works quite well but my gut feeling tells me there's more output power to be harvested if the B+ is increased.
The best idea I can come up with using parts I already own would be a 360-0-360V AnTek toroid followed by a 430-440V Zener string and a big Mosfet as a pass device.
IDH tube rectifiers would solve the startup problem but the current draw is close to 300mA (almost 1/3 of that through the cathode follower driver stages).

Any advice for a current production Mosfet (or IGBT, or whatever) that would survive this situation in the long run?

hi.

I am working on a DD Z2B in its output section. After it arrived at the workshop, I replaced the 28x 24n50f, 28x 33ohm gate resistors, irs2184s, 4x tc4452vat, 18v zener diodes, 7812 2A, checked resistors and everything was ok.
I started the amp and it blew up one side almost completely.
What could be causing this problem?

thank you.

Hello alltogether,

since the Twisted Pear forum isn't really well attended anymore, I try to get some help here. I ran into a problem with a "vintage" Buffalo v 1.2 which still sounds really good. Maybe someone can help me:

My Buffalo 1.2 ist supplied via i2s from a css8416mux. All settings on the Buffalo are set for i2s. The output of the Buffalo goes straight into an IVY v 2.01. The combination plays music when the Mux is fed from the s/pdif in.

But

At my Buffalo 1.2 I measure a voltage offset on one channel when it is connected to the IVY (Out+=1.7V, Out-=0.7V, i2s connected no signal applied) and the same at the output of the IVY. I measure a DC offset of approx. 1V at the SE output. The signal at this output is then significantly quieter. For comparsion: At the other channel I measure Out+ = Out- = 1,56V

Without IVY connected, I get Out+ = Out- = 1.54V at the output of the strange channel.

Even if I connect a Ballsie Lite directly to the output, everything works without DC offset. Accordingly, the level on both channels is the same.

The IVY alone has no DC offset (all inputs on ground). I measure the input resistances In+ -> Ground 3.78 kOhm on both channels and In- -> Ground approx. 20 MOhm. This cannot be the reason for the difference between the channels.

Somehow this seems to be a bug (on the Buffalo?) that only occurs when it is operated as current-out.

I'm a bit at a loss, does anyone know how to help?

Best regards

Flo

Did the Americans ever make a great pentode (like the Mullard el37)?

Just wondering...

sold

I built this case around a Chinese amp board, the "PJW063." It's based on a TPA3255 amp IC and offers decent Bluetooth connectivity.

I've rewired the inputs (Bluetooth, 3.5mm jack, and RCA) to all go through the switches on the front panel and the 10k logarithmic potentiometer for volume control. I've also grounded everything to a ground pin on the board, including the back and front aluminum panels.

The wiring is messy, but it works. It still gets a slight hum when the unit is powered on, and in Bluetooth mode, the potentiometer makes a wiping sound when moved rapidly back and forth.

Are there any suggestions or improvements I can make to this, aesthetically or otherwise ? I was also if there are better amp board options if anyone has any suggestions they'd be welcome.

Thanks for taking a look. I can provide more information if needed.

Hi pals,
Starting a build thread for people who bought PCB from me and for my own future reference.
Will List in this thread materials and tools needed and actual construction in 4 different parts.

Since changing the PCB to UMS specs please see that PCB MOUNTING holes changed from 4-40 to M3 and hence hardware is also changed.
Materials
1 set PCB(include a left and Right channel )and CRC supply board.
400VA toroid transformer
Components(see excel sheet)
4U Chassis (either deluxe or Dissipante) with baseplate from DIYAUDIO store.
Good quality drill with bubble level or ideally a drill press
For tapping heat sinks 4 x 40 NC Tap and No 43 Drill Bit with cutting fluid and tap wrench.
A good quality temperature controlled soldering iron😉


Starting with heatsink
DIY store heatsinks comes in a plastic wrap; don't unwrap them in a hurry. We needed those plastics to mark things on! or you may have to use masking tapes.
Taping is the most labor intensive process. And if you are careful enough will end up with that DIY satisfaction or in complete despair with a broken tap inside heatsink. So be cautious!!!


Follow this video to the 'T', IT WORKED FOR ME ,so should work for you too. I never tapped anything before this project! It is not that hard.
YouTube


and I used this tap wrench Irwin T-Handle Tap Wrench - TR-1E 0-1/4" - Pipe Wrenches - Amazon.com


Along with Forney 20857 cutting fluid.


See the attached pdf for dimensions and position of drill holes. Position the lower end of boards, edge 3 to 3.5 cm from lower boarder of heatsink.
Please see that hole positions are different for left and right channels in attached pdf.
You can use a permanent marker to draw lines over plastic wrap .Once spots for drilling are marked place the corresponding PCB over and make sure the position is accurate. Don't skip this part. Measure twice and drill once. Those measurements are all in mm. Follow exactly what is shown in video....😎


The amp PCBs are designed for mounting the JFET/MOSFET on underside of PCB with legs vertical (in contrast to first watt designs). I don't have access to exotic heatsink like Papa does, and this works equally well too.
The mounting hardware is listed in parts list and will provide enough clearance to avoid pins of components from touching the heatsink. (Sorry ,EU fellas, they are in inches).Well ,you can pick the height you want but don't make it more than 1 cm as you may not have enough length for Mosfet pins to get through the holes. Semisouth Jfets however need some trimming of leads. Soldering FETS is the last part so don't solder anything yet.
Mounting holes for FETS are positioned 19 mm from center hole for JFET pins( of the three)and spaced 100mm apart(please see the pdf marked right hole position).
So leave these holes for the last. Once all PCB mounting holes are in place, mount the PCBS .Using a sharp needle mark center pin for both FETs on plastic sheet or masking tape underneath. The FET mounting holes are then marked using scale 19mm vertically from those marking. Again double check before punching hole. Now unmounts PCB and continue with drilling and tapping. Now all holes are ready and keep heatsink aside

Hi all,

I have an ACA Mini that needs a good home.
Works great but Idon't use it. I use my own custom variant of the ACA Mini because I'm crazy and like to make things.

This is built with the Kevin Heem board that he created before the official esstantaols kit was created in the
diyAudio store. https://www.diyaudio.com/community/threads/aca-mini-almost-clone-board.381616/

$20 plus shipping without the power supply.
$55 plus shipping with the supply.
Or you can get a supply from DigiKey or Mouser.
It's a Meanwell GSM90B24-P1M This is the bigger 90 watt supply.
The current completion kit ships with a smaller supply.

Please PM me if interested.

Steve

I recently acquired a passive jazz bass which I fell in love with the second I plugged in and played it.

Its a 60s style passive pickup fretless Fender Jazz, specifically a Jaco signature model. It sounds absolutely amazing plugged straight into an amp or DI. I would however like to install a preamp to give it more output and less noise in live settings without having to run both pickups at once to effectively cancel noise.

The problem is - no back cavity space for a preamp, let alone a battery. The front cavity is small, but could contain a small EMG preamp keeping the stock Vol-Vol-Tone control scheme. Routing a separate cavity is absolutely out of the question. Any ideas for a way to add a battery without mutilating the body?

I have another jazz bass with passive pickups which I used external power over a TRS cable to run the preamp. I just want to keep it simpler on this new one.

So the Q150’s showed up this morning…..$350 shipped to my door…..not a bad deal for a pair of cutting edge Coax drivers and a pretty decent crossover if you intend to listen slightly off axis.

First order of business will be to see if that resonance wiggle in the response between 1-2khz is enclosure related so I’ll do some measures on a flat open baffle outside. It’s a minor abberation and be honest, it never really bothered me with my pair that I use for nearfield clinical mix monitors from time to time…..but this has become a lot about nothing site these days so let’s identify and address it if possible.

Second order of business will be to follow my recent thoughts and mount and measure the drivers in a sphere….let’s see what the DI looks like from 400hz and up. The sphere will start out with a variable aperoidic vent and a 2nd order highnpass on the Uni Q……see how loud these can go when that little cone isn’t asked to play bass……the tweeter looks somewhat stressed in Erin’s power compression measures but some of that might be thermal and pressure gradient.

Does anyone have any experience with these A1943/C5200 PCBs? With the exception of the single pair, the double, tripple, and quad pair boards all basically function the same with the exception of the final output stage. I also provided a schematic of the PCB with a double pair. Sorry for the lousy schematic, I just hacked it together as fast as I could based on the PCB itself as one wasn't supplied. Also, for the diodes and smaller transistors, ignore the part numbers in the middle -- I didn't have models for those parts so I just grabbed generic parts and then added a label for the actual part.

Let me know what you guys think of these.

Local ad, maybe for an electric organ or something?

In the process of @ItsAllInMyHead mentoring me in building an Aleph J, the concept of a Dim Bulb Tester came up. I did a quick search in the forum but thought it might be helpful to any other dim bulbs out there to post what I found. I like the idea of having a switched outlet so I ordered this, and for the socket. Other than that, a 3 conductor power cord, 1 end cut off, and a work box for the outlet, super easy peasy. Add to that maybe 3 different wattage incandescent light bulbs and for about $15-$20 a nice way to test and possibly save an Oops!

I have some speakers that are almost done and I need to figure out the binding posts situation. They are veneered in cherry. I'd like something visually fancy. Speak on is my usual go to but it's gonna look kinda crap with these speakers. They are a 3 way with separate boxes for each driver but the tweeter doesn't need a set of posts.

I was looking at PE's posts and their plates for them, but the costs really add up super quick and they seem like they have a lot of metal, which I heard isn't ideal.

Thanks dudes.

This thread is for discussions about the Power Supply Soft Start Board (V3) in the store. This is an updated version of the Soft Start V2 boards, primarily to make them compatible with the 10x10 grid mounting pattern we've now standardized on so they can be easily mounted to Deluxe chassis baseplate, riser panels, front panels and/or heatsinks. Refer to the Soft Start V2 discussion thread for additional information.

Change History

• 2.0 First Production Version
• 2.0.1 Added board dimensions
• 3.0 New Layout
  • Double sided board
  • Moved AC in and Txfrmr connections to ends of board
  • Added Keystone connectors as option
  • Conforms to 10mm mounting grid
• For future changes
  • 
    Add polarity markers for electrolytic capacitor

Information

• Product Page
• BOM - Attached below (Last updated: Jan 14 2014)
• Schematic - Coming soon
• Dimensions - 110mm x 55mm

Something I can't appear to find an answer for.........
( Although I found info regarding 'Battery Powered' Vintage tube Radio's very interesting !)

' Can a separate 5 Volt / 3 Amp DC Supply be used for the Heater on a 5AR4 '.?

That is, something like this : https://cpc.farnell.com/ideal-power...pin-iec-vi/dp/PW04127?st=5 volt power supply

This one does have the 5volt -ve side attached to the Mains Earth, others don't.
I was just wondering if I could use a spare Marshall TX ( supplying the HT & 6.3 vac ) in a 1964 Vox AC30 that has blown its Mains TX.....with a separate DC supply mounted under its wooden shelf
just for the Rectifier Heater !

The good news is that it plays music!

The bad news is that it emits some smoke and smells bad!

It worked fine when I built it many years ago, not sure what went wrong in the interim.

Free to a good home, just send me a shipping label.

Info here: https://www.diyaudio.com/community/threads/mezmerize-dcb1-building-thread.176723/

I am selling the transformer separately.

https://www.diyaudio.com/community/...er-115-115-15-15-transformer-on-board.411983/

Used this with the DCB1 listed here:

https://www.diyaudio.com/community/threads/smokin-hot-built-dcb1.411982/

Works fine.

$35 shipped within mainland USA.

Payment via PayPal.

Thanks.

I need to replace a couple of flat ribbon cables on my Arcam A10 Amplifier.
It has printed on it AWM 2896.

It is a 22pin Flat cable 1mm pitch.
I can source replacements from China but I cannot match the 2896 number.
The number they provide is 20624.

Would it be compatible?

Hello all. Just received my new shibata cut stylus from Jico, for my much loved ADC XLM MM cart. The instruction manual/warranty note says:
'Although the criteria for replacing stylus vary depending on conditions of use, it is recommended to replace the stylus after approximately 100-200 playing hours (SAS-stylus 500 playing hours).'

Dude!!! Thats only a few months at best! For a 200USD needle?

My ADC cart has the original stylus still on it, and it is probably from the mid '80s if not earlier. It sounds great to me, but I figures it time to try a new stylus just for ***** and giggles.

Any real world experiences regarding stylus life? This just cannot be... 200hours... jeeezuss!

I am starting to understand the need for two arms on my TT. One for background listening and one for precious late night music enjoyment.

Whats your favourite tube internals..

1. Copper grid posts vs stainless

2. Matt anode vs shiny/reflective

3. Copper anode vs graphite

4. Grey anode vs black

5. Getter D vs O vs pinched

6. Overhung filaments vs underhung

Etc

Hello

These are the Electrocompaniet AW100 output transistors I need to replace. As they are now impossible to find, what can I use to replace them.
Little diode seems to have some but pictures are not the same as the NECs I have. In the past, I always had good things from this place. It was costly but always worked.
Any other suggestions ?
Thanks

Does anyone know the actual equations for crossover frequencies of Steve Bench's third order crossover?

mike

Got here some heatsinks in the closet....
300 x 180 x 50 mm.
Is there a chance how to measure/calculate the thermal coefficient of this heatsink ?

So, I was wandering through my friend's scrap warehouse and saw these two units that had just came in so I grabbed them figuring they may have some useful components.

It appears that they were used for audio/visual projects or institutional P.A. systems as they have some interesting features such as a 28 Volt DC aux output and 70V/25V speaker outputs. There are two 2N3773 transistors on the heat sinks. I powered them up and tested the DC outputs and they were a bit higher than advertised, but both units read the same 32 Volts. I hooked up a music source and plugged a speaker in and they worked.

My level of audio knowledge is mediocre, so I stopped there until I can understand the following statement "the balanced outputs for 70.7 volts and 25 volts are for speakers designed for constant voltage lines. Each speaker must have a line matching transformer and the speakers muct be connectted in parallel."

The output impedences are listed as follows 70.7V = 83.3 ohms, 25 Volts = 10.4 ohms

Anywho, I am planning to work up to building a 30-50 Watt guitar combo amp sometime in the future (2x10 or 2x12) and wondered if this unit could be upgraded to potentially accomplish the task at some point. I assume they could drive two 8 ohm speakers as is, but the internal circuitry is perhaps not "high fidelity" At the very least the transfomers, chassis, and/or heat sinks could be repurposed I suppose. I was planning on using a high end chip amp for my main power for my first guitar amp, but these might come in handy for a later project.

Any thoughts?

I found TME while shopping for a Brymen meter a few years ago and the pricing was great, delivery was way faster than expected but it never occurred to me to use them for smaller ticket items.
They just put a 9lb package on my PNW doorstep in 4 days for $13.
That's Poland > Washington.
My suppliers across Puget Sound will UPS a 2lb box that takes 2-3 days for only twice as much. *Bonus- no tax.
If they're not on your radar, it might be worth a look... cheers.
-1 point for barely adequate packaging
+1 point for Stonecold Heatsink pricing

Looking for a pair of 165GMF or 165-2000 drivers please as a midrange for a 3-way project.
Cheers, Rob (UK)

I had a pair a couple of years ago but sold them due to house move. Looking for another pair (or quad).

I'll think it will become an integrated amp. With direct-in or something as an alternative.

As usual I started by giving the transformers (Transformers by https://jr-tubeaudio.com/) a makeover. With some hammerite and I gave them my Magnequest EXO-800 brass shrouds. (Exo-800 are small enough to put under a chassis)

Choke is a One-Electron UBT-1 (Primaries only ofcourse) that was the odd one out. (I once built a three channel 6c41c for my home theatre. But only ever used it for stereo)

Gave the covers a coat or two of Urethane because I hate polishing brass since my stint in the South African Navy 😉



Mock up:

Hello,
From the Sinus Live SLA1500 like class d amps, i have a defective driverboard MODU1. But don't know the type of the defaced IC's on there.
I can see a 74HC00 on the right, Who know's the partnumbers of the other two IC's, opamp and comparator i think?

I'm looking for the datasheet for the CS4303 evaluation board, named CDB4303. Does anyone have this stored away somewhere on their hard drive?

Hello Folks, can anyone tell me this circuit can drive the KT88 ? According to original design it is driving EL34.
If it does, any parts’ value need to be changed ?

I am the original purchaser of this complete DAC. It is described in this thread: https://www.diyaudio.com/community/threads/dac-end-r-es9018-full-assembled-board.228755/post-3410121

I used it for a year or two, then moved a few times using only a single AV system. I just used it for a few days and confirmed that it works as it should.

Light scratches on the top.

Smoke-free home.

Price includes shipping within USA mainland.

Payment via PayPal.

Thanks.