I am trying to solve the crosstalk problem of a Adcom gfp555ii. Looking at the schematic I found that the circuit board is connected to the chassis via a capacitor but there is a 10 ohm resistor which is connected to no where. Is there anything wrong and is it related to the crosstalk problem, i.e. I can hear the music through Tape In when the cd is connected to the CD input?

I was impressed by the review of this made in China amp where he actually opens it up
for a look inside. How about those 6L6GCs for 15W? Sounds good too:
PRS MT 15 Mark Tremonti Amplifier| An Inside and Out in Depth Review with Playing | Tony Mckenzie - YouTube

This guy measures about 25W:
PRS MT15 - Real Maximum Output Power Measured - YouTube

Perhaps the real Tiny Terror!

Might be good inspiration for a cheap build.

How accurate are the online software calculators for figuring out the components for a parallel notch filter? I have found more than a couple on the net. I'll be working on the 2 to 8Khz range.

I'm trying to tone down the highs on my Frugel-horn Fostex Fe108EZ's. I want to attenuate the range from 2Khz to 8Khz at least 3dB. I would need to buy high-quality capacitors, so buying and trying experimentation would get very expensive very fast.

Any advice or pointers would be greatly appreciated. Thanks.

Doug

I bought a 2.hand.

I want to ask a question, Q155(2SD669)&Q158(2SB649) are very hot. They are 45C after 1,2 min. turn on. Also, they are power supply regulator transistor of somewhere 🙂 I don't know. But, they're not for power amplifier main supply.

In service manuel, in the circuit diagram it's 2sd669 (1.5A transistor), but in part list it's KSC2690AYSTU (1.2A transistor). In amplifier they used KSC2690AYSTU.

Is this normal NAD design (Too hot transistors)???

There is no problem in sound.

If your interested in music production, music theory, or just music, hears a great youtube channel. You don't have to be a musician to appreciate it. The quote in the title is from this video.

Why Don't Record Labels Believe In Young Artists? - YouTube

Looking at toroidal trafos on ebay and an interesting one came up out of an Arcam av receiver. I downloaded the manual and found the trafo windings.

It seems that the main power amp section rails are switchable by a relay. I dont know what controls the relay.

Am I right in my assumptions here.? Looks like it can either run on the 36v or 29v rails.

Why might this be, just out of interest?

Thanks

Would like to swap Baby Huey EL34 PCB for Baby Huey EL84 PCB, or buy BH EL84 PCB, swap for tubes etc etc.

Please PM if you are interested/can assist.

Thanks.

I have tried this schematic (a combination of components of various ZENs) as a preamp for Zen9 and got an unexpected good and powerful sound. The jFET is a russian vertical SIT transistor KP926A with the triode-like output characteristics. Quiescent current is 150 mA, what seems to be crazy for a preamp. Undistorted sinusuidal output voltage is up to 27V, that is good for a power follower.

I purchased a couple of tiny boards based on the PAM8610 chip from Ebay. About $10. I want a tiny amp to feed my portable "Think-Geek" "crystal" speakers.

This chip feeds the class-D switched signal straight to the speakers, without any filtering. I added a few ferrite beads...

Works OK, until you get a transient bass-drum. That sends the amp into fits, with a noise I will describe as a "racous burp." 8W+8W of sine wave at 30Hz is fine, the transient bass is what sends the PAM8610 into fits.

Has anybody any idea where I should be looking to ameliorate the problem. I already have a huge cap on the power rail 🙂 I suspect it is some form of bootstrapping with too lower a capacitor value... has anybody any suggestions?

Hi all.

I fancy giving one of these cheap DACs a try, but I have two OPAMP options. Can anyone help please with regards to the differences? I am looking for a smoother, lusher, organic more euphoric sound then, especially on vocals, and something not over etched digital with less glare then if thats possible between the choice of the two. Any one any ideas to the differences please?

Hope someone can help me choose.


https://www.aliexpress.com/item/1005001966656478.html?spm=a2g0s.8937460.0.0.55012e0efO6PWn

I have some pots/attenuators that I’d like to clear for new projects. All are new, unused.

Noble 10K potentiometer, coming with pre-soldered board. 4 pieces. $59/ea

24-step attenuator. This one has twice the number of resistors (4x24) for a stereo unit. All Vishay Dale resistors. 4 pieces. $35/ea.

Shipping worldwide is $15.

Can someone point me at a supply for the attached hybrid amplifier? Any kits out there that would work well for this design?

I have a pair of tympani iva's which I had planned to use in the new house. It seems though that even in the large main room of the house, they are a bit overwhelming to some...So I am considering using just the mid/tweeter panel, using an ob dipole servo sub (gr research/rhythmic) for the lows. Not sure where the tympani's cross over to the mid panel. Anyone know if this is feasible? If not, any suggestions?

Thanks!

Hi ya
I need some carbon resistors arcol if possible I'm having trouble getting 22meg ohm 5% ones. But also need
9.1r
100r
10k
27k
150k x 2
220k
1 meg
3.3 meg
10 meg
22 meg x 5
Have you these in stock?

Hope I'm in the right place.

Cheers Chris

I am looking to build a bass cabinet with two Beyma's 10BR60 per side.

Crossed to an almost full range Alpair 7.3

Powered by Rotel RMB1048 and MiniDSP 2x8

To look a little like the B&W 800D with a curved back panel.

I like sealed, and with two drivers more achievable however open to all suggestions.

Thanks

Hello,

I am making a passive tone filter for electric guitar. The rotary switch is used to switch between different values caps. Simple circuit where the guitar plugs in directly (unamplified) to the circuit then out to an amp.

Like a passive preamp? However the rotary switch I use creates a scratching sound when switching. Could anyone recommend a "smooth action" rotary switch that does not add noise to the circuit?

Greatly appreciated,
TonyAm

Hello!

My name is M, looking to do a first build before getting into the larger sound reinforcement builds.

Does anyone have any suggestions? I was kinda thinking about a pair of studio monitors and a sub to work with them.

Thanks!

Looking to pickup a pair of marty subwoofers (mini, cube, johnny) or comparable. I'm open to 18" preferably, and other options. Located in Toronto.

Thanks

I inserted a Thermistor (Amphenol CL-60) in between the power transformer 550V secondary and the 83 tube rectifier (see schematic below).

Typical turn on sequence is as follows:
1. flip Switch #1 to turn on 120Vac to the power amp. This sends the appropropriate Vac to each of the tube filaments, but not the B+.

2. Wait 30+ seconds as the filaments come up to speed

3. flip Switch #2 to send 550Vac to the 83 rectifier and thru the power supply

The thermistor was supposed to slowly ramp up the current and thus avoid the loud "pop" caused by the current surge. Unfortunately, the current surge is still there and so is the "pop" noise.

Why is the pop still occuring? Thoughts?

Having previous experience with Alpair 10P in a Mar-ken end Pencil enclosures i plan to give a try to the new Markaudio CHN-110 in a 23L vented enclosure that i already have from a previous project. I plan to tune it similarly to the Pelorus since it has similar dimensions.
Now, i also have a nice Seas 19TFF tweeter that seams as match for a two way configuration but unfortunately i'm no crossover wizard to be sure that this wil work. I know the basics of calculating one just the Impedance curve of the CHN troubles me. It also has two coil inductances stated, namely one @1K and one @10K which confuses me in calculating a possible Zobel network.
Ideally i would like to keep the crossover to first order Butterworth (theoretically the drivers do allow it).

Any help and opinions concerning these matters are very welcome.

Oliver

I have the following Class D amp boards :-

2 x TPA3116
Tripath 2024
2 x IRS2092
2 X STA 508

I fancy trying a new flavour but there are many new boards and the chip numbers mean nothing to me. Which of those listed below would anyone reccomend?

TDA 7492 7498 8954

PAM 8403 8406 8610

TPA 3110 3118 3255

TSA 8498

info: Dynamic&Passion Hi Fi XLR Balanced Single ended Preamplifier Board Valve 12AU7 Tube Preamp DIY Kit American ARC Circuit|tube preamp|tube preamp diypreamplifier board - AliExpress

i bought this kit from china and built it. all components and connections function correctly (all the correct voltages at the power supply and everywhere else. ) except the volume pot. i had issues there and i took it out. you will have to figure out if you will put a new one in or will baypass it. the circuit is based on audio research and sounds amazing. so right now it is fully built except that the volume pot is taken out because it wasnt functioning correctly. other than adjusting volume i used this to play music with astounding results.




i am moving and this is free. just pay for shipping. transformers not included. this is just for the kit

price is free and shipping is $15. i only accept paypal and wont ship outside of conus because i dont wanna deal with that shipping.

Imgur: The magic of the Internet

if you want all the transformers (the power ones and the bal/se conversion ones) it is $89 for everything including shipping.

Imgur: The magic of the Internet

Imgur: The magic of the Internet

transformers are edcore and the correct specs for this pre

tubes are not included

the IO board comes with Neutric XLR connectors (that i will include in place of the incredibly janky ones that came with the kit). the RCA are the ones that came with the kit and they are great.

Conventional stereo recordings can capture acoustic images from a horizontal arc of up to 180 degrees, which I believe is known as the "stereo field", or a "sound field". However, conventional two speaker systems can only produce a stereo field of 20 to 30 degrees (or so), This is because the field is created between the speakers, and if they are placed more than 30 degrees (or so) apart the central images become progressively bloated and diffuse.

Whilst AV systems are primarily designed for recordings mixed for multi-channel systems, not conventional stereo. They do try to accommodate stereo recordings, and Dolby Pro Logic II can even derive an AV 5.1 mix from a stereo source. However, the latter is the opposite of what I'm seeking to achieve.

I use an AV system as a convenient and inexpensive donor of hardware to reconfigure for the reproduction of stereo recordings. My priority is to widen the reproduction of the stereo field, by feeding each of the two input channels to two or three speakers without mixing, cross-feeding or manipulating the stereo source (other than the setting of the volume levels fed to individual speakers). This rules out the use of a center speaker, and the single rear speaker of an AV 6.1 system.

I have developed an analogue unit that can vary the presentation of a stereo source from 1 to 3 times the speaker-to-speaker spacing, whilst maintaining the overall volume within 1dB. Furthermore, the unit is not only passive, it is purely resistive, and so has no "sound" of its own to colour the presentation.

Sounds too good to be true? I have a system set up and I'd love to demonstrate it to anyone willing to listen. Well, when Covid restrictions allow... I'm also setting up an area on my blog giving instructions on how to build a simple fixed-setting unit, and even how to set up a system without a unit, just using phono "Y" cables. I'll give the link when it is available, assuming that does not contradict any site rules?

Hello all,
i'm just getting back into DIY speakers after quite some time away. This is my first post on this forum.

I am planning a project using drivers from the KEF Q150B. I'm taking the drivers out and making a Tline (or similar) with low level Xover with bi-amping.

I just bought a pair of Q150Bs and need to get the T/S numbers. I have done a bunch of searching but have not been able to get the T/S parameters online.

Does anyone have them or seen them online?

I bought a Dayton Dats system but it wont ship for a few weeks and wanted to start doing some design work.


thanks
Mauro

- I was wondering should I just treat the car door as if it is a regular home speaker enclosure .... trying to make it as solid as I can using some kind of CLD treatments
and then adding some kind of foam to absorb the sound bouncing around inside the door???


- or just do the normal treatments you see on YouTube?

--- What are the best ways that you have found to treat car doors for sound???

As the title says.......
In being on the internet regularly for 30 years now, I'm not once ever had the pleasure of being hijacked, hacked, or had a PC virus take over the computer that I was using.
Since Windows 1.1, through almost all the versions, minus a few like Vista, Win7, and on various computers, now using "10" but....... nothing.
Oh sure, I've had HDD failures, memory crapouts, the normal stuff, ya know.
But never a virus.
Never had a problem with my e-mails either

Is it because I'm lucky?
Is it because I've got the common sense to not "click" on strange websites or links?
I dunno.

And lord knows, I've been on a plethora of websites, downloaded countless stuff through the decades.
And yes, even that "racy stuff" too. 😱

For the longest time, I felt that those anti-virus programs like Norton, etc, were just BS, just another marketing gimmick to make money off of paranoid people.
I still suspect that the recently reported hacks are generated to scare the public.

How come I never got "infected"?

Dear All, this is a thread for all members and mods and other audio personalities who passed, we will surely miss them....

let me start, Tinitus, diyaudio mod....

In your experience is matching the output and input impedance critical? My amp's input impedance is only 22.1K and I'm considering building a tube pre with a fairly high output impedance. In your experience will a "mis-match" in theory result in anything audible, like weak bass?

hi
i'm going to order some components from https://avnetexpress.avnet.com
i found 2SC5200N at a good price and the same for 2SA1943N .. the main power consumption and electrical specs are the same ... is there a problem using it as output stage instead of 2SC5200/2Sa1943?

have anyone ordered before from that site? they are authorized distributer for ST and some others

Regards

Hello All I have a RCA WV-98C That I have been tinkering with for quiet awhile now and I was wondering is there a solid-state meter than can test out beyond 50megs like this vtvm can.

I think this old rca is suffering from a weak meter movement and I am wanting to move on to something new that will give me less trouble.

Hi All,

I am looking for a pair of:

Scanspeak Discovery 10F/4424G Drivers

Scanspeak D2004/6020 Tweeters (or similar sized 4Ohm tweeter for Car use)

Located in UK

Cheers, Rob

Good morning. Thank you for accepting me into the forum.

My beloved CD304 Mk1 is having some issues. I remember buying it new in the mid 80's from Lasky's in Tottenham Court Road, London, costing about £350. Everything about it is original, apart from a new drive belt.

Anyway, as the title suggests, I am getting no sound - most of the time.

Sometimes a CD will play straight away for a few minutes, make a popping noise, and then nothing, although the laser seems to be still reading the CD, as the tracks still display, and the track time still increases, until the next track, and keeps going, but no sound.

Sometimes a CD will not play for a few minutes, and then randomly start playing, usually the whole way through, although longer CD's will start to have reading issues towards the end.

I am a bit geeky, so have read through articles on the internet, and have tried a few things, like prodding and flexing the two back-to-back boards with a pencil end whilst playing a CD. Nothing has materialised.

I have also read that the blue Philips capacitors can be the culprit. I have done much soldering over the years, so am happy to do that, but cannot find a definitive list of which capacitors to buy - is there such a thing?

Any ideas would be much appreciated. Thank you.

Hey everyone,

This might be a silly question to some 😕 but I am a bit lost trying to find out what type of xover I need, my situation is my amps do not have outputs for subwoofers and I would like to add one to my system.

So the question is what sort of xover will I need? And would it go before or after my pre-amp?

Thanks!

Ignore, rooky error- Pioneer SX-626 sweep frequency response

Hi All

IGNORE below, probe was on 10x Aaaarh!!! Lol. Cannot seem to delet a post ?

A neighbor has asked me to have a look at his old Pioneer SX-626. Nice old amp, like the satin finish.

It had a blown protection fuse on one channel and after replacing that I checked some voltages which all seem fine, AM/FM seems to work also. Dim bulb no issues. When I feed in a signal and increase the volume to say 5-10 Volts RMS at 10kHz it looks clean on the scope. Problem is if I then do a sweep (or change the frequency) from 20Hz to 20kHz the amplitude varies enormously from about 1V right up to clipping ? I can't recall which end it clips, I need to setup again. I should point out all the transistors on the amplifier section appear ok but I am yet to check all the capacitors. I was just wondering what the likely culprits might be ?

Any help appreciated

Cheers

Richard

I appreciate this is a question that depends on a whole load of "what if" scenarios, but has anyone experienced Scan Speak's paper 18W/8531G00 and Kevlar 21W/8554-00, and might be able to offer advice on the sound (as compared to one another)?

I have a pair of 45L ported speakers (Wilmslow Audio Nemesis) using the 21W/8554-00 with the D2905/9500 treble, and really enjoy the sound they produce. Unfortunately one of the 8554 drivers has died, and I've so far been unable to source a replacement.

As I have the D2905/9500 tweeters I've been thinking about building Troels Gravesen's SP95 design (SP95) as I understand the 18W/8531G00 is highly rated.

I assume an 18W wouldn't match the larger 21W for bass output in the lowest frequencies, but I cross over the speakers with a pair of sealed subwoofers so that shouldn't be a concern.

Any thoughts/guidance/experience appreciated.

Hi all!


My good friend Richard gave me his amazing casts of the JBL H9800 horns. They are pretty gorgeous and I have only tinkered with them so far seeing how horn loading works.





The new year is coming and I want to upgrade/design a new system utilizing this horn as it isn't an item I would normally have access to, so my plan has a couple of options in my eyes and I wonder if you guys could give your thoughts, please?


Atm my system is an MTM comprised of CAT378 and two FaitalPro 3FE25 and an SB Acoustics SB23 8" subwoofer each side - sealed. I drive this with two Parasound Zamps anda Behringer iNuke for the sub. I use a MiniDSP 8x8 for all crossovers etc. Here it is as it stands:





Space and budget is at a premium.


Proposal 1 (cheapest/best WAF):

- H9800 Horn with suitable compression driver - can I get close to 20k??
- 1x Faital Pro 8PR200
- Keep the SB subwoofers as stands

Using the H9800 vertically is also an option!

Stack as shown in mock up:







Proposal 2 (more expensive/less WAF)

- H9800 Horn with suitable compression driver - can I get close to 20k?
- 2x Faital Pro 8PR200 in a vertical 2.5 config. Design an MLTL that will go to 40hz-ish. Specs say the double xmax will accomodate this
- Scrap the SB subs

Build 80cm floorstanders for the woofers and mount the horn on top.



As far as compression drivers are concerned I have been looking at JBL 2450J. The snout will have to be removed for these drivers to fit the H9800. These drivers will also give me the opportunity to later upgrade to the beryllium diaphragms should someone die and leave me lots of money.

The 2450J seem to tail off towards 20k but I wonder with judicious use of EQ will make them acceptable and have a decent dispersion characteristics?



Are there any other compression drivers that might fit the bill? Budget is about £200 per CD.

I don't really want to add a supertweeter but if needs be...



Am I on the right track here? My wife will simply not tolerate a 12" woofer and cabinet let alone a 15" so smaller woofers are a must.

Any advice welcome! 🙂

Both SG505 and DA4084 have balanced inputs/outputs. When I am measuring THD of an amplifier, which doesn't have balanced input, should i connect "-" output of SG505 directly to DA4084 or leave it unconnected?

I need a pair of Raytheon 5687WA with black plates and D- getter
They have to be tested with proved results.
I am based in Warsaw, Poland, EU.

I might be able to make USPS large or medium flat rate box lots.
Not sure how that will work though.
If the past is a good predictor of the future, then it will be confusing and I will give up 😀
Or pick up in Nashua NH USA

$160 OBO for everything if you pick up.

- Laptech crystal 11.2896 MHz SC-cut
- Driscoll TWTMC-DRIXO-F 11. 2896 MHz
- Frequency doubler TWTMC-DBM-F 11.2896 MHz to 22.5792 MHz
- Sine to square 2 frequencies switched output TWTMC-STS-FSDO-S
- Hammond Box Driscoll
- Hammond Box Doubler
- Cable 1 x RG400 SMA-SMA 20cm/7.87inch
- Cable 2 x RG400 SMA-SMA 10cm/3.94inch
- Cable 1 x SMA-U.FL 15cm

Price: SOLD!

Micke, Sweden

Hi folks,

I've been AWOL for a while (life gets in the way sometimes😉).

I need some help with a fault on my NAD C320. The amp is failing to come on line. When I press the front panel on button the LED stays amber for 30-45 seconds then the protection relay kicks in and the red LED comes on.

Further investigation revealed that the R channel in the power amp circuit was getting warm pretty quickly on power up compared to the L channel. I checked out the voltage for the idling current settings between TP 3 & 4 and it was 11mV (should be 3-5mV). I confirmed the L channel between TP 1 & 2 and it was bang on 3mV.

Adjustment of VR12 had zero effect on the idling current on the R channel. There is no sign of physical damage or overheating on any any of the adjacent components.

Any ideas?

Can anyone recommend a good company that can repair electret headphones?

Specifically I have a pair of Toshiba HR-811 Electret headphones that are playing intermittently and I suspect the inline transformer has something to do with it so its bit beyond my skill level to repair. Given the fact that they're electret cans I'm hoping there someone reputable that can take them on.

I have an old Toshiba laptop that I use with W7 for software that can't run on W10. The battery is dead and will no longer charge so is it better to leave it in or remove it? At this stage the date and time are holding over extended periods (6 month+) so I assume the battery for that is fine.

I am home on leave so had some time to putter away in LTspice (dangerous). Looking at possible 6EM7 amps I decided to take a look at fixed bias. I normally think in terms of cathode bias for simplicity and lack of maintenance but I thought I should look at fixed in this case since as a low powered amp the likelihood of being driven into blocking is higher. Fixed bias allows me to direct couple a CF to the grid of the power tube eliminating that cap and also the cathode bypass cap. As a bonus I guess you get the ability to drive the grid slightly positive but that is really not a big concern for me.

Well the simulations were really encouraging and as a bonus it seems there is a non-trivial increase in max power output. If you are starting with relatively high power the extra isn't a huge deal but when you are starting at just a couple of watts it is kind of nice.

This is what I was looking at.



The FB loop is primarily to make for consistent gain since I intend to use it later as a phase for an input transformer split PP amp. I could use the 6EM7 small signal triode for gain and another higher current triode for the CF but that complicates the layout and wiring to keep gain stage away from PS and output. I have reduced C1 to .033uf as it seemed unnecessarily large.

I am curious as to whether the biasing scheme is reasonable. It would be fed by either a separate transformer tap or possibly its own transformer. R6 and R15 are the bias pot and the two 1 Meg resistors R16 and 17 are from the wiper to each end to prevent runaway if the pot's wiper goes open.

Hi Gents,
Stumble onto this, sounds surprisingly good.

DIY Tinfoil Ribbon Speaker : 8 Steps (with Pictures) - Instructables

This is probably more of a "what you feel comfortable with" type question. Anyhow, The transistors in the VAS stage of an amplifier (current source and amplifying) heat up to 140f / 60c at idle. Since the VAS is class A, they don't heat up anymore with a signal. Of course, this is far from the danger zone but no one would run transistors at max junction temp continuously. I know the cooler the better, so at what temperature would you consider heat sinking them?

HI,

I am selling all my electronics stuff. Here are the tubes. All sets are matched.

# EA
9 EL84 15 135
12 6L6GC 23 276
2 6550 44.5 89
2 EL34 18.5 37
3 GZ34 20 60
1 5U4GB 18.5 18.5
1 EZ81 15.5 15.5
2 5881 24 48
12 ECC83S 14 168
3 ECC81 14 42
3 ECC82 14 42
3 12AY7 17 51
2 5751 15.75 31.5

Total 1013.5

I have around 50 other tubes that work by did not test out perfect that you can have for free with the deal.

That is what I payed for them so make me an offer.

Billy email planobillyfl@gmail.com 305-923-3624 Miami

I did get these up and running, ebay won't let me revise the listing though. See additional pictures.
Audio Precision System Two + Controller + DCX-127 | eBay

Hello guys and gals. I have been interested in the Burning Amp competition and am wondering if there are rules or competition guidelines posted somewhere? I am interested in doing a similar DIY thing in the Detroit area.

TIA

Hello,
Just wondering if anyone has seen, heard or though about these...The design premise is pretty smart, just curious about how good it would sound...

Ballou Projects

have someone the manual (with schematics) of such machine? I have some problem with input selector and volume controls

Hi Guys,

I have everything needed to build tube electronics. I have a pretty large amout of materials. Lots of new tubes.

This is my tube tester. Works well. I can make photos or videos of all this stuff if anyone is interested.



You can contact me here or at planobillyfl@gmail.com.

Thanks,

Billy

Just for fun and curiosity, is it possible to make something very much like the MooseFet IRF710, except with the major difference being phase splitter duties for bridging amplifiers?

Purchased these custom built last year from Chinese vendor for tube amp/ sound bar project, but went SS instead. 6k CT primary (DCR is 219 ohms, both within 1 ohm). 0-4-8-16 ohm secondary- Rated 10W each.
$50 for pair + $20 ship to lower 48.
Thanks for looking,
Jim

Built and tested,working fine.
Amp board and PSU + 2 20VA trafos.



180 euro + shipping

A while ago I had a couple threads going related to making modifications/upgrades to a pair of PSB Image 2B speakers. Here are the links for reference.

Anybody ever modify PSB Image 2Bs? Worth it? What did you do?

Am I interpreting this information correctly? (Tweeter selection problem)

Here is the schematic for the crossover:



The Pos+ wire going to the tweeter is yellow, the Neg- is blue.

One of the mods I made to the speakers was swapping the original tweeters out for some better ones made by Peerless.

When I was replacing the tweeter on the second speaker, I noticed that the OEM tweeter was wired in reverse polarity. Blue to Pos+. I had never removed this tweeter from the cabinet before and it was the OEM PSB tweeter so I assume either the previous owner pulled the tweeter out at some point and wired it backwards when reinstalling it or it could've come from the factory wired that way; either by mistake or on purpose.

I didn't really look at how the tweeter in the first speaker I did the tweeter swap/upgrade on was wired so I don't know how it was wired. I knew from looking at the crossover that the yellow wire was Pos+ and the blue wire was Neg- so I just pulled the wires off it without noting how it was wired and then I wired in the replacement tweeter with yellow to Pos+ and blue to Neg- without giving it a second thought.

So then I get to the second speaker and notice that the tweeter was wired in reverse polarity; Blue to Pos+, Yellow to Neg-. I didn't think to check if the woofer was wired in reverse too in which case the woofer and tweeter would be in phase. I can check tomorrow when I get out to my cabin but if I recall correctly, the woofer has different sized spade terminals for Pos+ and Neg- so it can probably only be wired one way.

I'll know more tomorrow but for now I'd like to know is there a chance the factory/designer could have wanted the tweeters wired out of phase with the woofers? Is there ever ANY reason why you'd deliberately wire the tweeters out of phase with the woofers on 2-way speakers?

Starting my SSE build today. Looks like my R13 and R23 are slightly larger than the spacing, can I install anyway using longer leads slightly bent under? I am planning a one-side build on the PCB.

I have two almost identical preamps that I built. Both hum similarly at above about half volume (using Khozmo ladder attenuators). Hum increases with increases in volume after the "half-way" point.
I'm looking for a way to measure this on the bench with either an oscilloscope or a multimeter set to AC.
Any instructions would be welcome.

Is there any?

Crestron 16x60 Mod Project: 12V triggerd, Bridgeable to 5x200W/6x60W
I have just completed modifying my Crestron 16x60 to have 5 8 ohm bridgeable channels.

The amplifier is bridgeable using a simple toggle switch without the need for their external bridge modules. I did this by changing the amplifier boards to match the exact circuit that they use on their bridgeable 2x60 amplifier!


I have been looking at Crestron amplifiers for a while now given that they have so many channels and are made by ATI. In the past I had modified a 2x60 amplifier to work without cresnet just using an external 24V power supply.

This modification to the 16x60 goes much further in a lot of ways. It changes the system to fully run on a 12v trigger. 12V Trigger Modification details:

The main relay was replaced with an equivalent 12V version.

The crestron control board was removed and replaced with a 12V trigger via a 3.5mm mono connector (one or the other can be used, they aren't intended to be used at the same time). This is connected to the main relay via a small custom PCB. The amp still requires a 12v trigger input in order to turn on because it has no standby transformer of its own. Alternatively I also added a DC input jack so that a 12V wall wart could be used instead of the 12v trigger.



Due to the cost of replacing all of the output board relays with 12V relays they were removed and replaced with 20ga copper wires. The relay control and output monitoring board was also removed which simplifies things and gives more space. Many amplifiers such as my Adcoms don't use output board relays, this can result in a small power on pop but is not a problem.

I suppose I could have left the 24v relays there and could have made them work via a 12v trigger if I was willing to use both a 24V wall wart and add a relay to switch the 24v input with the 12v trigger. For my use model I just removed the output board relays instead but in retrospect it required a lot of desoldering and it might have been easier to add the extra relay and just deal with the wall wart.



The Bridging Idea

While the amps will probably drive 80watts or more to each channel before distortion I was curious to see if they couble be bridged...

Bridging it pairs channels (which are already on a shared board) and makes the amp much more useful in a home theater environment giving it a great deal of power on 5 channels with 6 channels left at 60w to drive surround or atmos speakers. This amplifier can now be used to handle 7.4.1 atmos all in one package.

My custom Crestron 16x60 can now be configured the following ways:

16x60, 2x200@8ohm/12x60, 3x200@8ohm/10x60, 4x200@8ohm/8x60, 5x200@8ohm/6x60

The Crestron 2x60 amplifier is exactly the same schematically as the 12x60 and 16x60 crestron amplifiers except it has one channel per amplifier board instead of two and it is bridgeable. The bridge feature turns out to just be a switch on the input board along with a feedback resistor.

Bridged Specs for the 2x60 are:

Output Power 20Hz to 20kHz, both channels driven at rated THD:
200 watts at 8 ohms bridged
Power Bandwidth 3Hz to 50kHz, +0/-3dB
Total Harmonic Distortion (THD) ≤0.03% at full power

The 16x60 is actually listed as 220W when bridged with external CNXBRMO modules but they specify to only bridge 4 channels. I bridged 5 channels and don't see this as an issue for home theater where it is very very rare to power more than 3 channels at full power. Rather than claiming 220W it seems more reasonbale to expect 200W given that it is using the bridge circuit from the 2x60 amplifier. I made every attempt to keep my addon board very compact to emulate the 2x60 design.

Bridge Module Addition/Modification Method
I found an article on Elliot Sound Products describing project 20:

Simplest Ever Bridging Adapter for Amplifiers


I was curious and discovered that this is EXACTLY what crestron did on the 2x60 amplifier except the crestron has input filter capacitors on both the non inverting and inverting inputs.

I duplicated the circuit from the 2x60 on this board:

The top pin of the connector is the output to the bridge switch from the 28k feedback resistor that comes from the positive phase amplifier output.
The bottom pin of the connector is the input from the bridge switch which connects to the top pin.

The two capacitors connect in parallel from the 1k resistor to ground and the input (bottom pin).
The white jumper wire on the left connects the square capacitor output to the inverted input of the bridged amp.

The white jumper wire on the right connects to the input side of the electrolytic capacitor.
The outputs of the capacitors connect to the bottom left pin which goes directly to the inverted input of the negative phase amplifier.



I desoldered and reused the input capacitors (C8A/C9A) from the 16x60 inverting input (the 1k input resistor R14A can also be resused). I then added a high quality 1% 28k resistor to the circuit as the only new component other than the board/wires/switch. The 2x60 amplifier has this resistor on each amplifier board (even though only one uses it) so that the boards are interchangable.

Note that instead of buying 28k resistors there are many of them on the output sampling board that is not needed for a standalone amplifier. This was one of the boards that I removed so they could have been stolen from that board.

Note that I chose to modify channel A on this board which is the Left channel to stay with the convention of having the Right channel be the positive side of the bridged amplifier. This picture shows the green board version of a 16x60 board which was my prototype where the yellow board version has a slightly different layout and component naming. The differences are very small for the most part. The yellow board also uses different output devices on the amplifiers which surprised me.

The red wire is from the ouptut of the Right channel to the feedback resistor on the bridge circuit. The board already has a via there to go to the other side of the board so I simply sucked out the solder and added the wire through the via (soldering it on both sides of the board).

The 1k resistor is connected to ground and if the bridge circuit is not enabled it connects GND->1k->Input Filter->Inverting Input.



The board connects to Ground via the top connection where C9A was removed from the board. The right side of R14A goes to the inverting input of the amplifier. The board connects to the other side of those components just to hold it in place. There is no connecto to the board accross C8 but I filled in the vias with solder just to make the best possible electrical connection back to ground.

The changes to the board can easily be undone if desired.



The addon board is then soldered to the back side of the amplifier board using 4 header pins (which happen to align close enough to work well).



I then drilled holes on the back panel of the 16x60 to add a DPDT switch. The 2x60 uses a 3 position switch such that it supports Stereo, Bridged, and Summing (the right input also feeds the left amplifier in dual mono mode). The switch is directly on the input board of the 2x60. I got a deal on some 2 position switches so I skipped the Summing (dual mono) configuration.

I must say that it is CRITICAL to use the best switch you can find. I initially experimented with some ebay switches and found that they added cross channel distortion when used. I had to buy top of the line ALCO switches to eliminate the noise. Once I did that there is no extra cross channel distortion from the switch.



To connect the switch I de-soldered the ground pin from the left RCA input and put the ground connection in the same circuit board hold with it and re-soldered it and connected the other end to the switch. For input grounding I simply soldered directly to the back side of the RCA connector (which is a very easy and robust solder point).

I then used a twisted pair wire back from the switch to the bridging addon board.

The good thing about the 2x60's bridge circuit design is that if the switch is open then it is as if the bridge module isn't there, it only connects the feedback resistor when the switch is in bridge mode. I actually have 6 modified boards in my amplifer but one of them isn't connected and it works as normal.

New back Panel:
I originally drilled holes to add bridging modules to all 8 boards but then realized that I only need 5 channels to be bridged. I plugged the holes with stainless hardware. It is possible to rearrange the boards but I found it best to distribute the bridged channels accross the two torroid transformers.

I need to redo the labels with my label maker and get them on squarely at some point.



Removed components:

Bag of 24v output relays
Original 24v main relay
Crestron Control board
Output board (and wires) for crestron controller power monitoring.
Output wires from the distortion detect to the crestron board.



-Rich

I have the following question:
When a pentode is working in triode mode (and in the case where the suppressor grid is not internally connected to cathode) which is the best way to connect the suppressor grid, to anode or to cathode?

Thinking of this, my mind says that a connection to anode seems to be better, as there is no slowing down of the electron beam to anode.

In particular, I'm interested in getting some advice regarding the Russian 6J9P-E pentode. This tube has its pin No. 8 connected both to the suppressor grind and an internal shield. So, what is the best connection of pin 8 in triode mode?

I have Noticed is that there is really no Software that I can tell that is just Click and Buy on the Play store that allows you to purchase a Full Out 8 channel DSP that would require nothing but a CHEAP $15 dollar USB 7.1 sound card.

Nothing I can tell. sure there are custom software, but nothing easy that is just point click and run.


There is NO reason why all of us don't have access to any app like this. Almost ALL Mobile Platforms have some sort of GPU that can do Math for Processing. Just like a DSP. So that takes care of the Low Power Parts from even 2015.


With so much hardware reaching EOL? Its a great time to have something like this.

Almost ALL Android and Mobile stuff like Tablets have Wifi. That takes care of ANY bandwidth problems for piping audio and you always have Bluetooth for control or Wi-Fi or you can also do it directly via USB or ethernet with a simple OTG adapter cable. even the fire stick from Amazon support OTG.

it just boggles my mind with all the custom software out there , something like this does not exist.

it's not like there isn't a market for it. heck.

it can even be advertiser supported.

if anyone knows of anything like this I would love to hear about it.
if there's a way to make a custom USB sound driver I don't see why this should be such a problem. you shouldn't need root permissions for sound.



BTW? it should have an interface exactly like some of the commercial DSP software packages like from JL Audio or even some of the Chinese manufacturers which are basically copies of Dayton's DSP GUI thats just a copy of another Copy. Can't be that hard.


there are now at least a hundred devices that are no longer officially supported by Google anymore with software updates and security patches so there are a plethora of devices to use that would work perfect as the hardware host and are stable, low power and don't have to worry about some patch bricking the software for the Active DSP/Crossover software.

It does not have to be PERFECT. This would be a great tool to show kids what they can do with sound and a simple device that they may already have.

it might even open up Android style gaming for using extra speakers for sound effects might be kind of cool.

it's API could even be used for some sound based games,
imagine what you could do with a Android tablet and a haunted house with just multiple cheap USB cards connected to it and having sound routed around via these little zigbee devices which would connect to the tablet playing the sound is a person went by.

there are some days I wish I was just a decently good-looking woman because I could probably get something like this done in about a month.
but I am unfortunately a man.
and therefore I have to do everything myself.

let me also say that there is no substitution for great hardware and I really do think that a stand-alone bsp really is the way to go for many applications especially in the automotive environment.

but something like this should exist for at least testing purposes and other uses and basically just for fun. without the hassle and complexity of actually going through and rooting a device installing a custom kernel putting in custom code yada yada yada you guys understand when I'm saying?

Everyone likes ice cream
but no one wants to go actually build the cow in order to get it.
no one Minds paying a little bit for the ice cream but honestly I'm not going to go ahead and build the cow, let alone making the farm.
that's a Cron job if I ever seen one.

the GU I would be cool if it was skinnable that way you can install or add in your own custom images to the items that you have in your system. This would make a lot more sense for those that are visually impaired learners or just plain stupid people.

the default setting should come out of the box with the usual default speaker settings depending on whether it's a three-way sound card or a four-way sound card.

voice feedback and simple instructions that are honorable should be the goal as you can test channels and it said they're going back to the software package you could just use your voice and say yes the first speaker is okay or yes the second speaker is okay or yes this is the mid-range it is set up and then you would move through the process, all with the power of your voice for just a basic setup.

there should also be a physical freaking book that you can purchase and it should be really good. you know how you read a book and you can just see images from just reading it that's how this will should be laid out.

and it should have tons of illustrations.

each and also have a mascot like how audio control has one.

a comic book for limited-release would be kind of neat too.
and we would use some things like I identify as a transducer or I identify as a bi as I am Full Range. Etc. Just Humor of the times.

all control knobs and their contributors and all the graphics within the program should have photos or pictures of the developer,

there should be lots of Easter eggs in it just for fun.

it also should be mainly web browser based as a web browser based on established w3c web browsing standards of the internet shouldn't be able to go into depravity anytime soon and the standards should be well within reach of lasting the next 10 or 20 years for its interface.

the underlying bits should be basically almost like switches in real life where you operate a switch and it pushes some software at the back end that way it could be universally compatible and transportable within platforms.

anyting custom will just simply use a whole new DSP engine on the back end and DC engines or virtual boxes would be able to be switched out at will.

the most basic version of the software should be able to work perfectly well on something like a $9 mini Raspberry Pi or some super low power chipset or SOC.

there should be a simple button or setting within the app where you can have it tell you if there's something wrong with your setup if it detects something.


the default software setting and the free version should come with the default voice of some Indian guy you can pay to upgrade it to a good sounding Swedish if you so desire or a British man.

if someone tried to hack the code or try to Pirate something in it should by default play the Jack Sparrow theme song.

instead of the software becoming unusable after awhile it will simply just randomly start playing the oH Bill oh Bill oh Bill!!!! if you know what I mean.

if there's going to be some kind of official Hardware it should be some official kind of Hardware that there is plenty of that is abandoned where that would work really well that way we're actually helping the environment by reducing e-waste. that way you can get large bundles and huge items of stock for pennies on the dollar.

each item that we or the software package supports or that is officially for the software should also officially come with Hardware upgrades to help the modding Community basically make these boards better and passed them on for everyone.

there should also be presets for audiophile speaker cables and we should release them on April fools every year and we should featuring you cable simulator.
the joke is they all sound the same and do nothing...
the inner joke is all the proceeds actually go to funding development for the project.



a cool feature would be integration with something like ampme which is a program that is available on the App Store that allows two phones or Android devices to play the same audio at the same time so technically you could use two Android devices at the same time and their headphone outputs as actor crossovers.
sure it won't work perfectly and there's going to be some delay but again this is for training and fun purposes.


the main reason I'm bringing all this up is that with all the computer power and with all the so-called just make it easy with an app. one of the things that is not available is a guy that is specifically tailored for audio and digital signal processing and how normal people implemented in their daily lives.


further development would be to add things such as the video camera and it would basically scan the room and then it would mathematically determine other factors that would help such as room length width and so forth.

imagine scanning a driver and being able to read its barcode or its serial number or its manufacturer has model number and then automatically add tsp presets or crossover points for that driver or speaker set if the manufacturer publishes it to the database.


the best part about this is that you can still use your audio output of choice for example if that's HDMI or an HDMI receiver that would be perfect or if you happen to have a cheap 7.1 Channel sound card you can use that if you have a topping back or sheeiiit DAC you can use that too.


the best part is it's not just going to be audio aficionados who going to be using this. the video gaming Community could really use something like this and that really opens up a whole entire New Market and the penetration of having awareness of good quality sound in room Acoustics really will enhance everyone's lives because we'll certainly see better products coming out .

Hi all,

Recently picked up a Cambridge Audio A5 amp from ebay to replace my A1 Mk3 se as I am having trouble finding replacement TDA1514A for that.

Anyway, the A5 seems to be a nice unit, however ive noticed that after 3/4s switching off the amplifier i get a kind of "squelch" noise.


I have traced it to the NE5532 Opamp in the Preamp stage (U105), i have desoldered the decoupling caps on that board and checked them (all ok) but did replace them with new good caps for the sake of it, but still get the noise.

Happens with or without a source connected and is attenuated by the volume control (so i know it is from U105). I have the attached scope capture from Pin 7 of the 5532, it is the same on pin 1 also.

Admittedly i can just make sure it is turned to zero before switching off, but wondered if this is a normal characteristic for the amp?

Edit: No idea why but my scope photo is upside down. will try to edit that.

Hi more than ma that buyed the Pedja Rogic Aya dac PCs card and populated that with component on the board and start to used it I have not don that Iam interested how it sounds?

Lars Ingemar

Hello everyone!


I'm working on a BT Speaker in a shape of a Pokeball. I'm done with the design and already started the 3D Print. Now I am close to finish the electrical stuff, but there is one problem left: My Design builds on the use of only one Speaker, thus elimanting the need for a stereo setup.



But I wasn't able to find any good BT mono receivers that would arrive in time since I need this Speaker to be done by November 20th.


So I ordered this CSR8645 Receiver with onboard Amplifiers
(CSR8645 Bluetooth 4.0 Amplifier Board 5W+5W APT-X Hifi Stereo Receiver Module - Raspberry Pi, Arduino, Robote, Motor etc. beim Eckstein Komponente, 13,95 €)


I read in the datasheet of the CSR8645 that it can be turned into mono mode, converting both stereo channels into mono channels.

But nowhere on the internet is it explained how to archive this.


So I hope someone here would be able to help me with this. First glance into the PSTool Sofware and the CSR ROOM config tool showed nothing that would set this. Or did I just overlooked the right option?


My alternative solution is based upon regular Stereo to Mono conversion:
Since the ... amp? of the CSR8645 chip itself is a Class AB amp (according to the datasheet which is a bit strange, since it gives no Wattage or any infos about the actual output of the CSR itself whatsoever), combining its outputs before they go into the auxillary class D amp should result in a mono signal which I could then lead into one of the class D amps on the backside.

Of course with resistors on both L+ and R+ when joining together(except L- and R-), and the needed capacitor and resistor which I will desolder to break the original contact between the csr chip and aux. amp.
Is this a considerable alternative?

WTB: Servo board for Philips CD PRO or PRO-2 transport .
Thanks.

High power transformers 2 x 46-52-56V 10A + support

For sale: a pair of very high power and very flexible transformers:

Primary: 115V and 230V

Secondary 1: center tapped 2 x 46V - 52V - 56V; 10A

Secondary 2: 4 x 16V 500mA, all 4 isolated from each other for max flexibility.
Can also be used as 115V to/from 230V mains converter.

These were custom build but I no longer need them. Looking for a good home.
Due to weight pickup only, Turnhout/Antwerpen area Belgium. Two available.

€ 75 each.

Jan

Been tossing around the idea of building a tapered array for a while now. I can't find much info on this subject aside from various attempts made by other hobbyists and would like to learn more before potentially wasting a lot money.

My main objective is to avoid outboard DSP with this. Yes, I'm aware of the potential costs and complexity pulling off a passive network to achieve this. Please don't beat me down on this. The reason I have for wanting to go passive is to keep the entire design analog to preserve the signal path. Im potentially open to active analog networks, but really would prefer to keep it all passive. I'm ok with losing some efficiency if I can pull it off passively.

There are 2 types of designs I'm looking at -

1 - Tapered FR array with smaller drivers (Visaton B80) + progressive LP filtering moving away from the array center in an attempt to avoid HF combing, although this may defeat benefits of a large array(?). I've heard the B80 and love how it sounds as a limited low end driver. It sort of reminds me of the Scan Speak 10F8414, just all around smoother and handles quite a bit of power, so it can play pretty loud within its other limitations.

2 - Tapered array with tweeter on center axis and Scan Speak 18W-5537G-01 midbass drivers, acting as a 2 way MTM in the array center @ listening axis and progressive LP filtering to outer drivers moving away from the array center. The midbass drivers are an OE version made for Thiel that I purchased as a bulk quantity online. They are beautiful PP cone drivers with TS specs optimized for a sealed or large vented enclosure. Specs are - Qts .49 / Fs 41Hz / Vas 23 ltrs / 87-88 dB@1W (driver not broken in yet). As a tweeeter, I chose the Morel CAT378 because of how it sounds, can deal with a lower HP frequency and has a waveguide which moves the acoustic center back close to that of the midbass drivers.

I'm open to any creative and helpful suggestions.

I have a number of SV572-160 tubes and wish to build an SE amp but cannot locate a suitable design. Can anyone help in this regard? Alternatively, what is required to adapt an SV572-10 design, of which there are several available online, to work with the 160 version tube? I have built many tube amps but this would my first using a power triode.

Bought these a while back, they are F-5C, that allowed for cascode and two pairs of outputs. Need old BOM! Believe they say V2 on them...

Any help much appreciated!

Russellc

Selling used and well working Ian Canada boards from a non smoking home:

Fifo II,
Dual Clock Board,
Isolator Board (finished and new)
S/PDIF Board



Price complete 200 euros plus shipping. / -with better TXCOs and a TPS7A regulator plus 20 euros

Thanks + regards

Josoeff

Searching a power supply for my Raspi in good conditions

Thanks + regards

Josoeff

I'm having this issue in my design where I have to warm up Q1 and Q7 with a finger to get idle current flowing. Once it's going, I can adjust the current and it stays fairly stable.

One stage at a time...

Is there any reason these DC operating points wouldn't be sufficient to drive the VAS? 36.7V at the mirror/LTP collectors is 2.7V more then the VAS Vbe of ~0.6V.

I was wondering if this 6" 1.5 Ohm sub driver can be used in an active DIY sub. It is from a Sony surround sound system. I have a Class D 100W amp for it, but not sure if such a low impedance driver would work.

Any reason why it shouldn't? Btw, it is a TPA3116D2 amp.

I've been cleaning out my "hobby closet" and found a trove of random capacitors I have no use for. They're sourced from: DigiKey, Mouser, Sonic Craft and Parts ConneXion. All are new and unused unless otherwise noted.

I'm selling them in one big lot. 72 caps total.

Make me an offer that works for you. $35 shipped anywhere in the US?


ELECTROLYTIC

(1) JJ 100uF 385V (Snap-in)
(1) ELNA SILMIC II 100uF 25V
(2) ELNA SILMIC II 33uF 50V
(4) Nichicon MUSE 100uF 100V
(2) Nichicon GN 560uF 400V
(1) Nichicon PZ 33uF 450V
(4) Nichicon PZ 47uF 450V
(6) Nichicon USW 10uf 25V
(11) Nichicon CS 10uF 400V
(8) Nichicon HM 3300uF 6.3V
(1) Nichicon HE 220uF 100V
(6) Nichicon CY 10uF 500V
(2) United Chemi-Con KZN 220uF 100V
(4) United Chemi-Con KMG 220uF 16V
(4) United Chemi-Con KZN 220uF 80V
(4) United Chemi-Con KZN 470uF 80V


CROSSOVER

(1) Mundorf M-Cap Supreme 5.6uF 600V
(2) Jantzen Cross-Cap 18uF 400V*

FILM & FOIL

(2) Rel-Cap RTE ( Polystyrene Film & Tin Foil) 1000pF 1000V
(1) Rel-Cap RT (Polystyrene and Tin foil) 0.039uF 600V
(2) Panasonic ECWF(L) (Metalized Polypropelene) 0.039uF 630V
(2) Panasonic ECWH(A) (Metalized Polypropelene) 0.039uF 800V
(1) Nichicon QXP (Metalized Polypropelene) 0.1uF 600V


*Tested for a few hours, but ultimately not used. Full leads. Never soldered.

Is there any sonic or functional detriment to using a step up or step down transformer to run a Japanese or European amplifier at North American voltages? If not, doing this would open up a lot of opportunities...

For Sale is my QA401 audio analyser, it has hardly been used.

If you are reading this you know what they are , a great little bit of kit.

Price $650 which includes shipping Australia wide.
Can be picked up from Sunbury Vic after hours or Mitcham during business hours.

I finally managed to grab a pair of Fostex FE206En drivers... I want to know what is the best enclosure to build?
no budget limitation
no matter one-mouthed or two-mouthed
no matter how long will it take
I just want the best possible option... how about Kirishima?