I've done a search which seems to suggest that this has been sorted but I can't use the official remote to select sources even after "learning" it (both sources learned to the source button).

It switches ok between SPDIF and Toslink from the software and all other buttons work. Also I understand it will only work when not connected to the PC so have checked that even powering the Nanodigi on/off in between.

Software version is v2.3
Firmware version is v2.11
All kit new out of box.

Any pointers to fix this would be gratefully received.

Hi Guys (and Nelson if your're reading this)
I recently bought a couple of vintage Thresold amps - an S200 and FET two (series 1) - I must admit I'm impressed - even though I've only listened for an hour or so.

The S200 seems like it might be a bit out on bias, but I think I found the document that illustrates how to correct this.

More seriously, the FET two has a loud "hushing" noise in the right RIAA channel - the line channels are OK, it's only using the "turntable" input (and by the way, the turntable input sounds really capable (despite the noise) judged by the limited listening I've done so far.

Anything I might be able to do my self? I know how to use my Fluke multimeter, and can build stuff - but am a novice in troubleshooting - and I have no schematic...

Best regards
Hans

Hi all,

I am trying to have my CSRA64215 module monitor and protect (against over-discharging) my single Li-Ion battery (18650 / Lipo) but i can't seem to get it working properly..

I know it must be possible somehow, but when I configure a so called "Battery threshold" it does nothing regardless of what I set the "Vbat Trigger source" to..



I also can't get my CSRA64215 to report battery percentage via Bluetooth. I actually don't know if that's even possible with this module but I've seen some lower-end modules that can do this so I don't see why this one couldn't

Anyone here that did got this working? Or am i doing something wrong here?

Any help is much appreciated!🙂

Hi,
Can anyone help me with a 6N16B project?

I have a few pieces and I would like to try a headphone amplifier.

Hi guys, I'm new to this forum and to audio, and I want to ask something about the 3 way speaker.

I recently restored a 20 y/o 3 way speaker system and the drivers are, as we know, have deteriorated, so I decided to replace them.
It originally has a 3" tweeter, a 5" midrange, and a 10" woofer. The tweeter still sounds good, but the other two doesn't. I replaced the midrange and woofer with 5" woofer and 10" woofer respectively.

Guess what, it sounds ok but definitely missing something, probably the midrange. Is there anything I can do to improve the sound? Probably replacing the woofer with midrange?

Important to note, the speaker system has NO crossover, and I'm thinking about adding one. Does two woofers in one enclosure sound bad?

So I'm building a thingy that has an opamp plus an external jiggery-pokery apparatus inside the feedback loop, and I want the complete assembly to be super stable (PM >> 45 deg) with little to no overshoot or ringing on the small signal square wave response (PM >= 65 deg).

Besides the externally compensated opamps that let you create whatever phase margin you wish (LM301, AD744, NE5534A but not '32), simply by adding an external compensation cap, what have YOU used to get big ole bohunker phase margin? Which chips?

AD817 and AD825 might possibly be two possible candidates (what do you think) ... neither of which is modeled in LTSPICE today.

Hi. I volunteered to modify the crossover points of a crossover. Existing crossover points were 250Hz and 2500Hz.

The 250Hz low pass sections look OK but in the mid-range and HF filters the response rises with decreasing frequency below about 60Hz. There would be significant drive at 20Hz and below to the MF drivers and tweeters.

Then I reverse-engineered the schematic shown below. It’s like nothing I’ve ever seen before.

You can see buffers and standard Sallen and Key 24dB Linkwitz-Riley 250Hz and 2500Hz low pass filters in there.

There are no standard Sallen and Key high-pass sections.

But what are IC2b, IC4a and IC6a and their associated resistors and capacitors? Simulating them in isolation shows they have a kind of peaked band-pass response.

IC4a doesn’t appear to be doing anything in that position and maybe should be in the high-pass section.

The output of some stages appears to be added/subtracted at various points.

The PCB is an old, custom single-sided affair with no resist or component markings. Maybe whoever layed it out made lots of mistakes.

Maybe I’ve made mistakes reverse-engineering the schematic but I’ve checked it a number of times.

Can anyone tell me what the designer might have been trying to achieve and what might be the advantage over a standard Sallen and Key topology?

Ultimately, I need to be able to change component values which is easy for the 2 low pass sections but not easy for the high pass sections.

In schematic for my Nad C272 it says adjust bias to 6-7.5mv.

Done,
but cooling fins basically never get any hot. It sounds good but after about 2h playing music it starts to sound much better i think.
My old 216, 214, 218 in the past and other amps i've owned before getting quite hot right away..

Only thing that gets really hot are the 68v regulator and all parts in pre and gainstage (suppose to run i class A so..) but the 4 pairs of Toshiba 1943/ 5200 doesn't really. after many hours of playing music putting the hand om the lid it barely is fingerwarm.

IS it any real danger of adjust higher like say 10 or even 15mv on bias? (my old 216 was biased at 18 i think but other trannies from Sanken)

Anyone experinced from this amp or another with this output trannies? Is the regulator or other parts take a beating if i adjust the bias upwards. Think really there is nothing wrong with the amp. Recapped and done. It was the same before this too.

Both Firefox and Opera are relentlessly bugging me that the site's security certificate has just expired.

I guess this is because I'm in an easterly time zone. Any Oz or Kiwis getting this too?

Hello,

I have come across a Hammond 500va isolation transformer. I do not truly understand the function of it.

Can it be used for audio gear? and will it improve sound and why?

Any experiences with isolation transformers would be appreciated.

Thanks

KevinLee

Over a few years I've heavily modified a Rega deck. It's the way I got back into DIY actually. I started out with a refurbished P3/24 deck, and then added a few simple add-ons to it. This was so effective that I went further and further. Now I'm not sure if my phono-stage may need improvement.

This is where I've got it to:

Deck (was P3/24):

• TT PSU
• Replacement plinth made from laminations of 15mm Birch ply to 45mm, veneered in walnut. Motor is mounted on 4mm aluminium chassis. Better feet currently being turned on the lathe with sorbothene bases.
• Subplinth of two laminations of 15mm ply, veneered as above, with P9 feet.
• ISOKinetik red belt, platter and sub-platter

Arm (was originally RB301):

• Paint removed and sanded to a 1000 grit fine finish, cartridge mounting area carefully sanded very flat.
• Arm drilled in a two-line pattern to reduce resonance.
• Spring based weight adjustment totally removed and ISO-weight fitted.
• Cardas to KLE plugs rewire
• Stuffed with a little foam near to the head shell (actually hearing protection foam seemed to work well)
• Benz Micro Ace High output cartridge.

Image of deck:


I can post a link to the detailed build on my blog if there is interest.

My question is (and I know it's a bit subjective): I'm currently using a Project tubebox IIse phono stage on this set up. It was bought a long time ago before I got back into DIY. One of the things I've noticed is that high output MC's have a much lower impedance than MM's, with Benz recommending 1000 ohm termination, this is not possible with my stage.

Is this phono pre-amp in the right ball-park for the above set-up? Or am I better building one of the many kits available?

A month or two ago, I say a post with some peoples preferences for signal switching relays for switching inputs and such. I can’t seem to find it again.

I’m looking for decent 12v options. If anyone can recommend I would appreciate it.

Thanks

Hi
I'm struggling with stripping 0.03mm stranded wires, the wire-stripper doesn't grip, and the coating is as "tough" as the wire itself, every second and third attempt I decapitate the wire...
What's your technique? a scalpel? Or is it only finesse, patience and training? (That's ok, but if there's a trick, I'd prefer to go with that 🙂 )

Thank you for sharing!
david

Hi!

I have a couple of questions about the Dissipante 2U chassis.

If I add a baseplate, what will the internal height be after the addition and what is the distance between the baseplate and the bottom cover?

Thanks!

Hey guys!

I bought this Ahuja HRC-32T tube amplifier a few months back for cheap and it has this awful oscillation going. It screams with a really high amplitude.

It uses three ECC83s and a pair of EL84s in pentode mode. It has 3 inputs which 2 of them are microphone inputs and a phono input on the back. One ECC83 is used as the pre-amp for the 2 microphone inputs and half of the second tube is used as the pre-amp for the phono input. The 3rd tube is a phase splitter and a tone control tube I believe?

Since I didn't need the 2 mic inputs, I removed the first tube and it's socket to make an amp. The removal of the first tube had no effect on the oscillation.

The original electrolytics were shot, so I replaced all of them. This reduced the hum significantly.
It didn't have a grid stopper resistor, so I added them. This had no effect on the oscillation.
I have also checked all the resistors and they are fine now. When I recieved this, one 110 Ohm screen stopper resistor was open and I replaced both of the resistors with 91 Ohm ones.

The current problems are:

- Oscillation. A 20V RMS signal on the control grids of the 2 EL84s. It goes away when I remove the phono pre-amp tube or when I remove the phase splitter/tone (?) tube. Also, fiddling with the mic 1 input knob kinda messes with the oscillation and I can see the glowing screen on the one tube go dim or brighten up.

- Red screening on one of the EL84s. It moves with the tube, however, I don't think that's the cause of the oscillation since it still happens when I remove that tube (or the other one).

- Amp starts clipping or distorting at like 1W. I think this amp should be able to do 20W.

This amp once made the motor boat sound and popped for a few seconds. Haven't been able to recreate that again.

All the voltages seem OK except the grid having that weird signal going in. (Plate: 337V, screen: 336V)

I have attached a few pictures of the amp.

Thanks for all the help.

Hi,
Can I anyhow add USB input to Allo Boss DAC? What are the solutions for the same? XMOS board or something? Sorry I am pretty new to audio world, so don't have much knowledge about digital audio.

I actually want to stream audio from Windows PC to Allo Boss. Not just streaming using DLNA but all the audio from Windows PC to Allo Boss, like we have it for Mac's (Airplay). Is there anything similar for Windows PC?

I am using Allo Boss with PiCorePlayer installed.

Thanks,
Simar

Currently, I like the Jazz Groove and even donated during their recent fund drive.

As I grew up in the 60 - 70's I'd like to find a similar "free" non-jazz streaming source of popular music from this era.

I recently hit upon such a station, but they are an FM broadcaster and clearly their internet stream is just a pipe of their highly COMPRESSED FM broadcast. So Too Bad - The music mix is fantastic IMHO

Anyone know of such a station? There's Radio Paradise of course with their FLAC streams, but unfortunately I cant stand any of their mixes and have to quit them in ~15 minutes...

Unlike the Jazz Groove, where I could easily listen all day long - or until I'm simply tired of Jazz / listening to music.

Thanks for any help with this!

Hello.
I really struggle to understand the concept of ground in audio, how come some ground can be tied together, but other need to be kept separated in the same amplifier
(I am not talking about the obvious digital vs analog ground).
Also why it's better to star ground sometime, but sometime it's better to daisy chain...but most importantly, how do you choose ?

I understand the concept of ground loops, and how they need to be kept small to prevent radiations, or act like antennas.

What I don't understand is : should ground be "classed together" by current.
Or should they tied together following the signal path ? (for example from the input connector daisy-chained until the bridge rectifier).
How to ground multiple PSU (+-15V, 350VB+, Negative Bias, heaters, and relay psu in the SAME amp) for the cleanest ground ?

My question(s) is idiot, unclear and probably badly formulated. But It's just that I am so lost, that I can't even understand how to grasp this concept to formulate it correctly.

Can you also recommend me some readings on "grounding for audio" ?
Or some complete schematic of 2 channel amps with full grounding, that are "perfect" grounding.

I have read a lot of the forum and this :
- http://www.valvewizard.co.uk/Grounding.pdf


EDIT ; you can skip the chassis ground, it has to be connected to the earth, and no current flows in it except under fault conditions.
"And the circuit will be connected to chassis at some point since this ensures the amplifier’s working voltages are properly defined with respect to zero volts, and that the chassis acts as a shield against electric fields. (Merlin Blencowe Designing Valve Preamps for Guitar and bass )"

Could somebody help in finding schematic for Denon PMA737 integrated amplifier? Or at least comment on topology? Owners manual claims that it is zero feedback amplifier!

Vintage Sangamo 15uf 1000VDC Paper in Oil(PIO) capacitor. Sangamo part number= CP72E1EG156K1. Made in USA. Unit in very good condition. Comes with mounting hardware. Removed from equipment and has been tested.



Asking 29.99 with free shipping in 48 states...all others plus shipping.
Payments via PayPal(jcameo7270@yahoo.com)


If outside the 48 states...contact me & we'll figure out best way to ship.

I have 3 questions if someone could help me out please!

1. I have driven some 5" speakers full range, without subs, at loud volumes. The Za5, to be exact. Not knowing what it would do, and still not sure if it has done anything. Is there a method/way to confirm if all the drivers (ZA5 Woofers) are working as they are supposed to be working? I don't hear anything wrong in the sound, but I just wonder if there is a test to do? I have UMIK-1 if it matters.

2. I had some families over, one of the kids (dont even know who), decided to dent both the tweeters (they are metal - titanium tweeters by Vifa). So obviously they'd need replacement aswell, am I right to assume that? I have pulled the dents out using tape, but they are not perfect and still have some small dents here and there.

3. Same as question 1, is there a test or a way to check if my crossover parts are all working fine? I got them assembled from madisound, so I am not saying they are not correctly connected, I am just asking is there a way to check if each component is working as it should be?

Been looking for an easy cheap louver solution.
Everything seems to be press type tool die.
$500-1500 all I've found.
Any suggestions...

I received this Amp. The owner drilled some mounting holes, and the chips falls inside. PS damaged, and one side of the Audio Bank.
PS is ok. I removed all mosfets from the damaged Audio bank,exchanged transistor Q13( Driveboard) (SMD Code DK) with a DF, which i just had on hand. The Amplitude looks good, the other side is working well. As soon, as i put the output mosfets in the damaged bank, the output filter starts make hissing noise, and all Amplitudes are gone. The mosfets in the damaged side heat up quickly. Also the Amplitude on the good side is gone or dropping. Maybe somebody has an idea.

I'm currently investigating the possibilities of improving the analogue audio coming from the multichannel board in my OPPO-203.

I've already fitted a linear power supply and an upgraded mainboard clock to the system, benefiting the DAC on the multichannel board.

I've come to the conclusion that a great way to start improving the board would be replacing the voltage regulators, capacitors and opamps.

See the below pictures for a great overlook of the board in its original state, and which components I aim to change.












All the green components are likely to be changed, the red components will stay, where the red square is the DAC (AK4458VN) and the other red capacitors can be changed, but they need to be replaced with the exact same values.

I'm not a firm believer that capacitors will yield such a big sound improvement, but more rather the opamps and then perhaps the voltage regulators, the capacitors might be able to improve the noise level.


What do you guys think?

Any do's, dont's?


I searched the internet for a bit and found out about audio buffer boards, they seem to apply a gain on the input and/or output stage to increase dynamics, could these be used here somewhere?

I'll have access to a digital microscope and a great soldering iron, I'm an electrician so I know my way around things, but not too good with electronics and SMD-devices and audio circuits in general.


Which components would be worthwhile replacing, which components affect the perceivable audio improvement the most?


The analogue board will be connected straight to an Emotiva XPA-3 Gen 3, feeding my needs for both music and home theater, the OPPO-203 is able to decode FLAC, DSD256, Dolby TrueHD and DTS-HD MA.


A fun project I think, what's your take on it?


Cheers!

Hi,
I am trying to make a acrylic chassis for Allo Boss streamer/dac.

I want to place two meanwell 5V 2a power supplies in the chassis only.

Will it make any effect on audio quality? Or do the position of two power supplies makes any difference? Can I place them in parallel or they have to be at 90 degree?

Please help me with this.

Thanks,
Simar

Looking at a service manual for an old subwoofer design by Kenwood which has emblazoned "sigma servo" on front to see what exactly they were on about. I've heard of servo woofers but not in the low end consumer market.

Anyway what I found was they were running a separate feed from the + terminal of the woofer for NFB. Which makes me think it is no more than just a bit of a gimmick for marketing purposes.

However it got me to thinking. Has anyone experimented with this arrangement and what effect did it have? Or otherwise have thoughts on the matter? It seems that it would be an opportunity to at least partially null out the effect of speaker cables but I can see it introducing a new set of problems (it may need to be shielded for longer runs, etc and the return would introduce its own distortion).

Hi all,
Background:
I am building a WAW system. I have completed the 8" woofer bass reflex part and am interested in a mid-transmission line for my full range units. I currently have a pair of MA Pluvia 7s, MA Alpair 5.2s and a pair of Fostex FE103ENs. They will sit in a space above the woofer and will be interchangeable (modular). The space available is 30cm wide (overall width of speaker 32.4cm), height 24cm (overall height of speaker 86cm) and a depth of 39cm. Crossover will be about 350Hz (300-400 range), 1st or 2nd order passive. My Pluvia 7s and Fostex are currently in temporary boxes and I have been experimenting with the xovers.
Question:
I am contemplating a simple square or rectangular open backed tube of 39cm depth minus the thickness of the baffle, lined and stuffed. Is there any advantage of going tapered, bearing in mind that I will be making several of these?

Greetings,

I'm an new member, first post. I have a Laffeyett PA 273 valve amp that I want to use as a practice amp because of size weight and coolness...

It has been sitting some time and before putting into service I want to update some components.

- two 50 MFD 25 VDC Capacitors
- two (I belive) 270 ohm resistors near the power lamp [Red, Violet, Brown, Silver]
- the power cord

Questions,
1) What advice, suggestions, wisdom can you share.
2) I can not fond a schematic for this item. I was told that it is made by Sano and is a Sano 16W model. Still I can not find a schematic.
1 12ax7
1 12au7
2 6bq5's and
1 6ca4 rectifier

with a 12" speaker.

3) I was looking on https://www.mouser.com. What is the suggested replacement Resistor - Manufacturer / part number

4) What is the suggested replacement Resistor - Manufacturer / part number?
How about this?
Vishay Mouser #:75-TVAN1206.1
Aluminum Electrolytic Capacitors-Axial Leaded 50uF 25volts
2 $3.35


Photos available at:
Valve Amp - Google Drive

Regards
Domenic

Right now I have a setup that consists of two multi-way (ported) enclosures plus a sealed subwoofer. These enclosures were originally tuned for something around 50 Hz (can't tell exactly, I've got them with the speakers trashed), but I've rebuilt the speakers to have a higher sensitivity at mid-bass (100 Hz up) as the subwoofer is taking care of 100 Hz below.

But still, It is a bit weak sometimes, and I want to increase its sensitivity instead of just pumping more power (even why, the speakers are near their limit already at 25 W RMS per channel, they won't go much higher than that).

Making horns for the tweeters is easy, but I guess a folded horn design for the woofers would result in way too large enclosures to carry around with a half-full family car.

I guess that regarding the sub, my only practical solution is actually using a ported or sealed design and using more power.

But is there something I could do about the woofers for the 100-3000 Hz range?

Thanks!

I have a BASH amp that needs repair. Not sure if this should go in the class D section or not (BASH class D-ish? 🙂 ) It comes out of a Klipsch SUB-12. From what I've diagnosed so far, one opamp is bad (easy fix), and some part of the digital converter/drain voltage modulator. It appears that both sets of output transistor pairs (IRFZ14 and IRF9Z14) are OK (tested with DMM, verified gate signal looks OK on oscilloscope). The FET that controls the drain voltage (IRF530) seems to test OK, but without the digital converter working correctly I can't be 100%. One part certainly seems to be missing, (R61) which is a series resistor going to the current sense line. The UC2842A VCC line only goes to 2V when it is installed, but without will go to 22V. I had tried multiple UC2842A chips, and all do the same thing so I assume that isn't the problem. Solving both of these problems seems to be first on the list to getting this amp up and going. I can't really identify where the +22V is sourced from either. One pin on the module goes from a cap to ground and that's the only trace I can see connected to the main PCB.

Does anybody have a schematic (long shot) or at least have a high quality picture of the board so I can identify a missing part vs a DNI? Any help or guidance on this amp would be helpful.

Up for sale is 1 Vintage Triad C-20A Reactor Choke rated 6H 400madc and 60 ohms...Asking 54.95. Unit is in very good physical condition and has been tested. Payments can be made via PayPal. Shipping will be a large flat rate box...I believe its 21.20. Thanks for viewing this item.

Hi.



I was searching for a discrete opamp designs and saw an old
article by W.Marshall Leach about high bandwidth preamp.
In the article he has two designs of a phono preamp and an
output stage. The designs are actually discrete opamps, one
using BJT's at input and the other FET's.


The opamp is designed to work with +-24v.
I ran simulations of the opamp and everything seems ok,
but for use with +-15v it's a bit weak.
Maybe I should add a current source for the LTP, any Ideas?


Help is appreciated...
Thanks,

Udi.

Edit: I used bc550/560 instead of the original 2n5210/5087


The schematics:

Hi friends
I received a diy-kit of a lm3886 dual mono poweramp (this one: 2x LM3886 68W Power Amplifier Kit (Mono)_Solid-State Amp_Analog Metric - DIY Audio Kit Developer)

The amplifiers are quite simple. For the PSU, there‘s a 2 x 24V 200VA toroid and 2 x 8 1000uF Elna capacitors...

Being a noob with ambitions, I ask myself wether anything should be improved on the basic design? Any tips welcome!

Complications will probably come with the details...

David

Hi
I have been using a Clearaudio Concept Turntable with Performer Cartridge.
In the last 6 months the stylus have been broken 4 times and I had to replace the cartridge. No explainable reason. I am in direct contact with Clearaudio in Germany but they could not figure out the reason. Even once I carried the whole Turntable and all settings were made onsite. Instead they helped me to replace the cartridge every time. But you can replace the stylus at Clearaudio Cartridges.

Now I want to try a different cartridge.Any one had a similar problem before with Clear audio? and what would be alternative cartridges?
Thank

I would be interested in hearing from anyone who has listened to both types of low power class A amplifiers with high efficiency speakers. Did you prefer one over the other or do they sound pretty much the same?

I'm 95% certain on this but, for DACs that use a wallwart to supply DC, you can buy one anywhere in the world and then simply buy a wallwart appropriate to your country's voltage, correct? In other words, I'm in America and I'm looking at a DAC sold in England. All I need is to buy an American wallwart at the same voltage and current and all is good, correct?

Have a 800va transformer with two 60v secondary wires. Have two amplifier boards that use a single + 83v. What is the best way to wire these to utilize both secondary windings? Should i half bridge with two rectifiers running each board off each secondary and cap? Right now i have been running it off one secondary, rectifier to two caps in parallel and both amp off the positive 83v.
Can I make two positive 83v terminals one for each amp board? I know this is , just a hobbyist and want to make sure im utilizing my power supply to its full potential. Secondary is two yellow 60v leads. Thanks in advance for any help!

OK, don't know if anyone has my issues anymore but thought to post anyway

My NCore NC400 with Hypex SMPS600 monoblocks were switching on - off repeatedly, especially on my difficult to drive ML CLS electrostats... I had thought oh, the Class D not playing nice with Electrostats issue...but when it was also doing it on my Maggies, I knew something was up...

After reading the following:

Dead Hypex SMPS600 V3 Power Supplies - notANON

I decided to recap the SMPS power supplies... as it gets somewhat hot and cooks those nearby caps. Being the lazy turd that I am, I just replaced the caps I had on hand, and focused on all the ones under the big heatsink - and yes, you have to remove the heatsink - I changed the three biggest caps - the two big 220v 820uf caps and the 50v 470uf...but on one SMPS I also changed the 35v 220uf (right up against the hot heatsink), and the SMPS other I forgot (it was 2 am).

Anyway, I was happy, but confused as one worked perfectly, while the other SMPS still had issues firing up and staying up.. until I remembered the 35v 220uf I forgot on one SMPS. I replaced it and both are good now.

Also the re calibrate the DC sense on the NC400 with 3 volts on the Mystery 5 pin block on NC400 pins 1 and 2 (neg on 1 pos on 2, with pin 1 closest to the block caps). I had two AAA batteries giving me 2.98vdc that I used, and the amp just stopped - it would no longer produce any sound even though the last cap replacement made it finally fire up and stay up with all LEDs, but sadly, no music.

Then I remembered someone here had done the same thing (two AAA batteries) but used a pair with a bit higher voltage - 3.09 vdc, and it finally worked. So I checked all combination of AAA batteries I had on hand until I got right around that 3.09 vdc and tried it - finally some music.....whew... I had them drive my ML CLS for a few hours at low, then high output and all is good again.

Now if I can just cancel that new SMPS600 from Hypex that I ordered before remembering that one cap I forgot yesterday, all will be really good again...

Got myself a Little Bear P7 tube amp a few days ago and paired it with 5670 GE tubes and a GE power tube. I have a few questions regarding how to mod this amp since I have no experience in diy electronics. I have soldered before and I got the hang of it quite fast. The Little bear P7 is the P8 version without a transformer but with a Switching power supply. I have a question on how to increase the gain of the amp to louder volumes to drive even harder headphones. Also at high gain with this amp there's distortion in the low end I'd like to fix. Which capacitors/components do I need to replace/bypass. I wish to use this knowledge to one day create my own headphone tube amp from scratch. I have basic knowledge of circuits boards and the safety procedures to not get electrocuted by capacitors.


Extra question: If I use a tube adapter (5670 to 6SN7) do I need to adjust the voltage from the PCB to run the 6SN7 tubes.

Sorry for all these questions and thanks in advance for helping this noob.

Hi all, would anyone know how to wire up the reset switch from the 12v output to use as on/off(standby) on the 3E board for the amp by putting reset into low/high. I'm very much a beginner trying to build an amp and would like to use the reset as my on/standby rather than surging current through the power supply/amp every time I turn it off and on. Hopefully the diagram will have uploaded Thanks for any help.

Hey guys.

So, I have had many people testify that multiple smaller subs will never have the same "sound" as a larger sub. I have also read where people will make this claim about midbass too.

However, I have never had anybody place any data behind the claim to back it up. There are are sorts of proclamations about greater visceral impact, weight of the sound, ect that are attributed larger woofers.

But what is the science behind this? It doesn't seem to make sense to me when all other factors are equal (cone area, displacement, ect). How can one subwoofer have more of the above attributes when compared to closely spaced multiple subs?

I am working on a PPSL design using multiple 8" (for car audio, but ignore that for the sake of the argument). But I am constantly reminded that they will not sound like a big 18" or a pair of 15"s

Does anybody have an explanation, or has this never been thoroughly explored?

Thanks.

Hi,

Intertechnik from Germany offers new full range speakers at a moderate price with 5", 6" and 8" diameter:

IT IT Lautsprecher Shop - AX-05 | Gradient :: Lautsprecher ::
IT IT Lautsprecher Shop - AX-06 | Gradient :: Lautsprecher ::
IT IT Lautsprecher Shop - AX-08 | Gradient :: Lautsprecher ::

As Gradient is only a Intertechnik label for cheaper drivers, those drivers should be produced somewhere else...

Has anyone seen these speakers yet and can give me some more information?

Bye,

Spatz

Hi ,

This is my first post.

I have a Copland CTA 401 hybrid amplifier.

It´s from the early 90´s.

NOW: I have been recommended to upgrade some of the capacitors in this amp. Especially the yellow caps ( like on the picture )

Should I let it be, or should I do this upgrade ?

Any other upgrades I should think of for this amplifier ?
( I have just changed the tubes )



- tralalalala

Hi all,

Recently I got bitten by the horn bug and I wanted to make one. It is WAY harder than I thought but ultimately quite rewarding.

Trying to find an easy to construct design I landed upon the Bill Waslo SynergyCalc spread sheet which is super easy to use! (attached with my current settings) I thought a microspeaker would be cheap and fun to play with so I ordered two Peerless PMT-20N12AL04-04 drivers.







Here are my attempts so far and my observations on the failings (thanks to input from others):

MK1 Spec

- Made of 0.5mm card and masking tape
- A 1" throat to fit the diameter of the driver











Raw response - Horizontal 0-15-30 degrees at about 70cm:




EQ'd Flat response - Horizontal 0-15-30 degrees at about 70cm:




Observations on failings

- It's made of flippin' thin card
- Throat is too big for the surface area of the driver
- Response bunches up from 5k onwards

I recently retrieved my original Sonab catalogue from the 1970's. I've scanned it for those who may still have some Sonab equipment (either stored away or still functioning)
I'm currently restoring 3 Sonab 4000P amplifiers and still have my original 1976 Sonab OA14 speakers. Still a great setup.

Hi, just to check interest here, to possible avoid eBay sale hassle.

For sale is classic Marantz 17 CD player, black. Very little used, fully functional and as I can see in "almost as new" optical condition.

CD was upgraded with new IEC and audio connectors, also switch for switching between digital ( SPDIF) input and output..so it can also be used as DAC

Asking for 300€ plus shipping ( around 25€ for EU..)

Regards, Davorin

Folks, Has anyone come across a multichannel relay "instant mute"/"delay on" small signal PCB? I need one to mount in an electronic crossover to prevent accidental pops and damage to speaker drivers. 6 channels total. There are loads with high current relays, but I need small signal relays. Cheers.

In a circuit like this would the grid leak current tend to charge or discharge the battery .

I see posts where someone needs a way to do input selection and I thought I could take my design that included digital volume control and a remote and pair it down to a six input fully balance/single ended and a muting circuit controlled by two buttons on the front panel of the preamp. it would consist of two boards, a display with seven segment LED to show the input and mute status and the two buttons, size of 2.5"x2.5", and the input board with the relays and a voltage regulator 4"x4", input for 8-12vdc or 5vdc and not need the regulator. Also a little power supply board if you didn't have the above voltage already present in the preamp. The PS would measure 2.5"x3". Cost about $65 USD with PS, minus $15 USD without.
Anyone interested. I can post schematics and BOM, and Gerbers.

Hi there!
Anybode got reliable info about how to replace Ferrofluid in 1" Tannoy Titanium Tweeters (6189 0063) from 2004 (199X-20XX?? i8, V8, etc.) ? Like: how much to apply and where to buy?

There seems to be different viscosity and magnetic propierties..

Thanks!
MH

Hello to all, I am new here!

8 March is soon :emoticon removed by moderation: and I want to present to my wife a new headphones, my budget is between 100-150 y.e., what you can advice, please?

My wife loves music and I need something good looking for women, something simple & TOP quality for this budjet.

Please, advice, ASAP, I am short of time. Hope you guys know everything about good sound, thanks!

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hello all,
I recently purchased a 2-way crossover off Amaz**.
it was supposed to be a 12db/octave Butterworth. but it is missing a capacitor on the woofer side??? so what kind of crossover is this?
It also has a series resistor of 2 ohms in line with the cap on the tweeter side. An attenuator by chance??

hooking it up, I find that the highs do get passed to the tweeter, but the woofer receive ALL frequencies... no blocked highs. and it is supposed to be crossing at about 4.3khz.

Any ideas what this circuit is? and can I assume it was designed wrong? or am I missing something?
see attachment.

Thanks.

So I finished a 3 way cab from a plans site, and I have all the drivers wires feet but not the crossover. It is supplied by another PA supplier but a lot more expensive per board. Now there is a 3 way passive crossover by Eminence (500Hz/3.5kHz) at $68 each 12 dB.slope. So my question is this, this will be used as a 3 way top and I just built ported 2x15 JBL loaded subs under will matter which crossover I use Eminence has the same xover points also will be used for DJ playback role with amps and BBE and EQ.
So will it matter? Custom built by a supplier is designed for 500 watts, while the Eminence 400 watts. I don't need all that power for my customers don't want concert volume backyard parties and small to medium halls capable for <250 peeps.😕

Hello speaker builders. I've been building for many years, but eased off recently - gave up battling the WAF problem with selling to individuals. A few years ago, I bought 24 Peerless 830875 HDS Nomex 6 1/2" midwoofs. I fancied building some kick-A line sources (I'm not an engineer, so that was a fantasy). I kept them because they are a premium midwoof with great TS params and great looking freq response curve 90/100 Hz to 3kHz, thinking I might do 2-way bookshelves with them. They are languishing in my garage and I want to see them used. I'll sell the whole lot of 24 for $40 each and I will pay the shipping cost. Small amounts $50 each plus you pay actual shipping. I am not a dealer or reseller, BTW.

Can anyone please explain this "independent 12-15v ac input"? Bought this kit off eBay. Hope someone is familiar. Thanks!

Greeting all
What would cause a 6550 turn black and rainbow at the top? It was supposed to be new, I put it into this Defy 7 (yeah, I know, pls don’t ask) that I’m working on, and it played fine for an hour or so, but then I saw it change color and shut it down. All surrounding circuitry tests fine. Socket leaking?

MMM Moving Mic Measurement

Hi all,

to measure loudspeakers in a room, here is a presentation of my MMM method.
It is not a revolutionary method but it is quick and reliable.
http://www.ohl.to/audio/downloads/MMM-moving-mic-measurement.pdf

Have you tried the elderly German raw speakers made for tubes, that generally get high dollar on epay? Generally 5K Ohms. A few are electromagnetic, but most are permanent mags. Made for Tube amp reproduction, 6" and larger, (some for Philips. Nice radio (most) and theater sound systems. These speakers differ from most USA radios, and the better magnets were made by (I think) a long German name with 'magnet' in them. They've got my attention. Any experience with DIY tube amps and that load combination?(Forgive me, but I still think Norelco/Philips tape recorder trannys which are usually 3 or 4 times the size of Tellys, are really nice single-ended iron. Sorry for a repeat of the Norelco/Philips iron rant!! Previous post that you graciously responded to. So please skip that part as an unwarranted addition but I'm a bit OCD about them).

Good morning!
I‘m distracting myself with some literature about wires, cables, interconnects etc.
Here and there I read about Spagetti. Nowhere did I found an explanation or illustration of it, so ...
What does Spagetti mean in the context of wires?
(like in DIY Silver RCA Interconnect Cables )

I'd like to share my recent repair experience with a Nakamichi CR-3E tape deck I was given for free (wasn't working). The most immediate problem I found was a melted capstan belt and weak back tension belt. I got the kit from EBay (seller: Revox) as I wouldn't invest in a kit from Marrs without knowing if this deck would work fine afterwards. This was a smart decision, as the deck turned out to have a lot of other issues and, well against what I've read around, the after-market belt kit I got is working very well. So, I then tested and the tapes would stop playing after a couple of minutes, wind-up reel would stop. I researched: it would be the typical blind spot problem of these Sankyo motors. I tested, holding reel with hands and in some places it would simply stop and not start again, which confirmed it. Decided to recondition the motor and did this quite successfully. Deck now was playing the entire tapes. BUT: quite a lot of wow (I think this is how it's called - with a sine wave test tape, the waveform was "floating around the zero line" a lot).

After some tests and investigation, and taking everything apart again, I noticed very clearly that the flywheels of the capstans showed some bad signs of age and wear - surface wasn't smooth, it made the belt "dance" and one of them even has fine cracks in the metal! I guess, if they were available as spares, they would need to be replaced. As they're not, I decided to try and recondition them... with very fine sandpaper and extreme caution I managed to polish their surface. After reassembly, the belt is now going smooth and that extreme wow in the waveform was gone! So I thought that now the deck was fine. Did usual cleaning and fine tuned the speed of the capstan (was a bit on the low side) and decided to keep it for myself, as the sound is amazing, never listened to tapes with this sound quality.

But then, a few days later, after it had been sitting around a bit as I didn't listen much to tapes at that time, I wanted to play a tape and it suddenly stopped again.
Was back to the sudden stop problem! I decided that this couldn't be normal and decided to measure again the voltage and research on the internet to find valid values. Oh well, it had some problem in the driver circuit! The reel motor was only receiving 1,8 volts during play! But it got the normal 5,3V during forward and rewind, which both worked fine. I tried the torque pot, but it was almost at max, the voltage didn't reach more than 1,9V at its max. So, electronic problem. Started to investigate the circuit (I have the service manual), but all componentes measure fine, still the voltages are incorrect! 🙁

Then I had a sudden and absolutely crazy idea 😀: instead of wasting hours to try and find the problem, why not build my own motor controller, which would only be activated during play/record, on rewind and fast forward the original controller would work, being my controller circuit bypassed. I decided to go for a very simple PWM circuit based on 555. Yes, crazy. It needed a lot of tweaking and changing, as in the beginning the frequency was way too low, making the motor whine, I then settled at about 35 kHz (well outside audible range), also the voltage turned out to be insufficient, in the end I opted for 9V and regulating the duty cycle very much close to the low end, so that motor wasn't too fast and didn't give too much torque, but still receiving higher voltage, hoping this would help to not oxidate and stall so soon again. It worked!!! the motor didn't stall. Or at least seemed so. Then it was quite a challenge to get the right logic signal to switch the bypassing (which was done in the most clean way possible with two relays, to avoid that the circuits could interfere, also it means this mod is totally reversible cutting a few wires and taking the circuit out and soldering the orignal wires, in case one day I'd find the defect or something), I finally managed with the signal which is output by one of the logic ICs which drives the Play LED on the front panel. So, my circuit was working fine! Problem now was the adjustment of the torque. It started to stall again!!! I drove it up in speed, but results were bad: too much torque, tape was getting pulled by reel motor now, clearly noticeable in bad sound, with "oscillation" on top of the sound and higher pitch. So I was going too far. But why would the motor stall if lower speed? Maybe it was beyond repair and I would really have to exchange the motor?

I decided not to give up on it yet and opened up the motor again. Oh well, it had oxidated quite a bit again! Maybe due to little use and the defective driver circuit which had it playing tapes at only 1,8V! I did a very thorough reconditioning until it was shining new. Reassembled. Yes, now I was able to lower speed until the capstans were in control again and sound got brilliant again. No stalling anymore! At least until now, fingers crossed!!!

Made recordings, wow and flutter improved, at least as far as I can see without having proper equipment. In general, it now sounds much better! Let's see if the motor manages. Unfortunately I have no torque tape so to be able to configure the perfect torque. As I don't know how the motor will do, I'm still planning to order a Mabuchi RF-510T as long as they're available, in case it starts stalling again.

So, this was my journey so far, never had modified a tape deck, or even heard of using a PWM controller to driver a reel motor, so feel free to call me crazy, but it's in fact working fine and solved this problem! If anyone wants more details or the schematic, I can try to provide it, I only have a sketch, don't have much time, but if necessary I can do this. Attached goes a photo of my circuit in place.

Hi, i have a strange problem with my avr. After a short power outage the avr turned back on but it was not displaying anymore on tv(hdmi) and it had also no sound from all inputs! If i do a factory reset it shows initialized but it takes 3,4 hours to reset, after that it works again(the only thing missing is the smart menu, setup screen is displayed ) until i turn it off (stand by).
I have the service manual the voltages seem fine when it has no A/V output, i dont have an o´scope for further measurements. I´ve noticed that ic731 (ADV7623) is getting hot, is this normal ? Can someone please help with this problem ?

Good evening all!

I’ve had a transformer hum issue with one of my monoblock amps and decided to test the DC offset.

Something rather strange seems to be happening!

Using my multimeter and testing at the speaker binding posts with no load (speakers) attached, I switch them off for a short while and then turned them on to test from cold. When I first switched them on, both amps had a very high DC offset - somewhere around 6volts! - this quickly came down in one amp and settled at 0.7 volts, however, the other amp was much slower to stabilise and is sitting at around 1.5 volts after 5 minutes.

After connecting the speakers and testing again with music playing I get a reading of zero on both........ so I decided to unplug the speakers from the amps and test again, I got a reading of almost zero on both amps........

Can anyone explain whats going on here?

Am I not testing correctly?

Hello

I have some pure copper pcbs that I have made .. just need some advice, i like the polished copper look. Can I laquer the pcb then solder at a later date ? do PCB lacquers allow soldering afterwards ? any recommendations ? I was planning to polish the PCB so nice and shiney then spray with a good PCB lacquer like this as a example Electrolube CPL200H Clear Protective Lacquer 200ml | Rapid Online
then solder later ... or should I populate the pcb then lacquer afterwards ??

you thoughts

regards

Hello! I managed to find my way here after searching Google for a few heat problems I'm having with a Rotel amplifier. I tried posting in the forum and my post didn't go through, so I looked up what might have gone wrong and it says I need to make an introduction, so here it is 🙂

Hi all, this is my first post here and I’m hoping to get some advice on a cheap amplifier.

I’ve been looking at the models which are in the thread title and I’m not sure which to go for. The amps are:

SMSL 36A PRO @ £45: This one seemed to have good reviews on here with the older module but it now uses a 7492 which is apparently of lower quality so I read the breeze audio amp is the one people go for now.

SMSL 36A PLUS @ £55: Amazon says it uses the 3118 but not sure if it’s the same as the recommended older-SMSL 36A Pro with 3118. There is not much talk of this amp on here.

SMSL SA50 @ £63: same with the 36a pro, it uses the 7492 chip.

Breeze Audio 3116 @ £28: this one I think is the one to go for these days.. however I’m not ordering it from eBay but from Amazon. Is this definitely the right one? I have seen people say some are dual and single chips but not sure really... DollaTek Breeze Mini Dual TPA3116 Digital Power: Amazon.co.uk: Electronics

Hope to get some advice.

Many thanks

Will

Edit: I forgot to add the amp will be used with a pair of second hand wharfedale Diamond 9.1’s I picked up second hand.

I've wanted to get some hands-on experience playing with circuits and such so I bought a USB 8 channel DAC kit and was hoping I could find some folks here that would be willing to guide me through the assembly. In exchange, I'm willing to write up the process as a guide for others in the future.

The board itself is an 8 channel ES9016 board here with this reclock between the USB input and DAC and the opamps here. I'm using this and this as the power supply.

My main questions are these:
1. What needs to be soldered and what does not? The site states "SMT components soldered, thru-hole components are not soldered", but it's not clear to me which is which. It is especially not clear how the opamps are attached to the board.

2. How consistent do the top/bottom lengths of the opamp pins need to be? For example, is it a problem that one side is longer as seen in the picture? Is it also ok if some opamps are connected by two sets of two pins (or one and three pins) instead of a single set of four pins? I had a lot of trouble resizing what was sent to fit.

3. What is the best order to approach assembly? Since the majority of my solder experience is with larger cables, I don't know what to expect when working with something this small.


4. How do I best go about getting power to each of the power supplies while minimizing the amount of outlets needed to power the DAC? I'd like to avoid having to provider a separate power outlet for each of the power supplies.

I'm sure there are more that will come up in the course of doing this, but any input on any of the above questions will be greatly appreciated. Thanks!

I have to sets of soundbar systems with 10" subwoofers..
Have anyone tried to reuse drivers from a soundbar?
I would like to build a stereo system using 4 drivers (mid and treble) and the sub in one enclosure.

I've recently bought a couple of monacor spx32-m attracted by their wooden phase plug and, of course, the price 40€ for the pair.

Now I did some calculations, and, considering their parameters thought to do a bass reflex 4-5L box.

Any ideas ? (I'm trying to avoid the subwoofer)

I have joined the Pass ranks. I purchased a used Threshold S150. Impressive build and I am looking forward to a long association with this amp.

The main PS caps have been replaced, otherwise it is a stock unit. It is also a standard bias unit, not an optical bias type. After a few hours of warming, the bias on left channel was 65mv, right 45mv. Dc offset was under 15mv on both channels. The original owner had not ever made any adjustments. With these setting, the left channel was only slightly warm, the right basically ambient. I set out to rebias the amp to a higher level. First up to 100mv on each channel and let it run for a few hours. Rechecked and found the bias has settled back to 65mv on each channel. I again raised the bias to 130mv, and after a few hours checked the bias at 100mv and the heat sink temp was aroung 105 F. The offset increased to around 24mv on each channel. I guess that there is still upside adjustment to reach the optimum operating level using the 10 sec touch rule. Then I turned the unit off for the evening.

Today I found a paper on the factory bias procedure, explaining the factory bias scheme. It indicates that the cold startup bias should be set for 180mv. I assume that is the peak reading that should be seen upon start up. I monitored the bias reading as I started the unit up cold and it exceeded the 180mv level, so I switched it off.
My question is this; If I plan to switch off the unit and not run it 24/7, should the bias be set to not exceed the 180mv level and accept the under optimum bias level? Am I being overly cautious?

Also, there are no Tantalum caps on this unit to be replaced, but there is two 4.7uf electros on each channel that are original. I guess that the recommendation would be to replace them. What is their purpose, and what is to be gained by their replacement?

Thanks...

Many years ago Bob Carver made one of his solid state amps sound like a very high cost tube amp. It convinced Stereophile they sounded the same. Anyone here know the details of what he did to his amp to achieve this? I here talk of matching transfer functions. What was done to do that? What parameters of the amp were altered?

Hi guys, does any one know how LTSpice decides on the order of 2 step commands?

For example:
.step param A list 1 2
.step param B list 3 4

When you run, which is the outer loop and which one is the inner loop?

I.e. do we get:

Sim 1: A=1 B=3
Sim 2: A=1 B=4
Sim 3: A=2 B=3
Sim 4: A=2 B=4

- OR -

Sim 1: A=1 B=3
Sim 2: A=2 B=3
Sim 3: A=1 B=4
Sim 4: A=2 B=4

Is there a way to force an order?

Thanks!
- Sandro

http://oi67.tinypic.com/708b4n.jpg

I have a project and do not know exactly how to define the working class for the final stage("class A2 means that the grid is driven MORE POSITIVE than the cathode for part or all of the waveform")
Your opinion counts
(sorry for my English)

As the title implies it's something to do with the past - at some point the industry decided suddenly that corrugated paper surrounds are no longer "good"... but why? I am asking this in the context of full range speakers, especially hi fi ones, perhaps I can understand why a subwoofer would have a surround made of rubber or foam but when it comes to fullrangers I suspect things are different. One observation I would like to point out is that on the used market if a driver has two versions one with paper surround the other what ever it's always the corrugated paper that is more sought after. So is the corrugated surround better? So people are looking for them but manufacturers refuse to make them?
How many hi fi models stil in production have corrugated surrounds? I know of Supravox (impregnated I think), other than that...? When was the last Fostex made with paper surround?
Another thing that should be mentioned is that paper surrounds are not exactly what they seem - I have measured a few and they are always thinner than the cone (half thin many times) so it's not a simple continuation of the cone but they don't seem to be glued either. In fact they are so thin many times you can see from behind how transparent they are in the right light.
And last but not least - can you buy a corrugated paper surround? to use on you existing speaker obviously.

Hello, I came from this old thread 'Differences in tweeter's sound by different kind of crossover' in which was said very interesting things which then I wasn't still ready to understand but now I may do.
In particular 'Cyberstudio' gave some interesting notions about even and odd order filter topology correlated with phase at cross point.
Now I may be ready to understand better these notions so I recall them so:

- given that two complex signals sums up right only when in phase, why an odd-order with two signals apart 90 degrees in phase at -3 dB has a flat power response and an even-order with two signals in phase at -6 dB hasn't a flat power response? In other words, what does it happens to on-axis and off-axis response between these two basic kind of approaches?

- another question: isn't 'sound quality' of two 90 degrees shifted and summed up signals worse than two signals in phase one?

Thank you very much.

ps @Cyberstudio: don't excuse for the basical kind of your explanation for me, I'm just a beginner..

Just wanted some advice about which direction to go in for improving my THD+N measurements. i.e. What is the next step?

Current Setup:
Focusrite 2i2 as is. No mods, no external oscillators, no level matching interfaces, no protection, no buffers.

Goals:
To measure as low as possible on a hobbyist budget. Hopefully something that can start to get a feel for how well Tom's modulus 86 composite amplifier boards are performing or at least move me further in that direction.

Things like the QA401 are a good option. But I'd like to do better if possible on a hobbyist budget. Instead of spending money on the QA401 are there better solutions?

Ideas:
Output buffer (I need 2V to measure amplifiers. Distortion from the output is a limiting factor for the 2i2)
Precision oscillators
Notch filters
Cordell distortion analyser
Get a different interface or DAC? Khadas tone board?
Are there dedicated ADC cards that are affordable with very low noise?

Can someone also advise what projects are active for level matching and input protection?

I don't think boards are currently available for Peter millet soundcard interface, linear audio autoranger or cordell distortion magnifier. Are there any active projects to improve the functionality and or performance of soundcards.

Where would you spend the time/money if you wanted to get improve upon a soundcard interface? I appreciate any advise