Hi,
I got this sub woofer without any other accessories. It has acoustimass square connector as attached. Its a square connector with 13 pins. One is 27V DC and one has 2.4V. Rest of them reads 0 V. I am trying to find the pinout diagram for this. Internal circuit has DSP so it is not that straight forward to find connections. Can some one help me finding pinout ? My final target to use this subwoofer as another subwoofer in my sound system. I still hope that this unit has analog input. If it is digital, then I am screwed.

Thanks,
Pubudu

Hi all,

So we all have used Rockwool or glass fibre for treating rooms etc... but now that more ecological, healthy materials are available, what do you think of them?
For example :
- Recycled newspaper panels with density of 32-42 kg/m3 available here in Finland (Ekovilla)
- Recycled cotton with density as low as 20 kg/m3
- Hemp
- Wood
- Sheep

What do you guys think when it comes to treating room and especially bass trapping

In Finland Ekovilla slabs (32-42 kg/m3) hasn't been measured but their blown wool of similar density has AFR of about 10 kPa*s/m2.

Manu

Just trying to learn about this and I find there are at least four ways to do it.

Looking from source to driver:

1.series cap, series coil, parallel cap, parallel coil

2. series cap, parallel coil, series coil, parallel coil

3. series coil, parallel cap series cap, parallel coil

4. series cap, series coil, parallel cap, series coil

They all appear to use about the same values for caps and coils.

I assume they all would work, but is there any real electrical or audible difference?

I've built a scaled-down version of the Zen amp to feed my Grado headphones.
The HexFets employed are the usual IRF610, both for the active side and for the current source.
The bias current I chose is 300mA, the power supply voltage about 30Vdc, for the maximum compatibility with Hi-Z headphones.
I've obtained best results taking advantage of Nelson's patent 5,710,522, this allows to halve the distortion figure and to increase the drive caapability: on 32 Ohms load I've measured over 8Vp-p without any apparent compression, as soon as possble I'll perform a standard measuring set.
The sound is beautiful, more natural (notwithstanding Grados..) than the RA-1, which is not that champion people believe, at least in my opinion...
😉
The input impedance can be set between 13KOhm ( freq. respnse as far as 80KHz) and 40KOhm ( upper -3dB limit 26KHz).
If someone would desire the schematic, I'll send it to him gladly.

I bought a pair of reference 3a mm generation 2 and the bass ports have fallen inside. I can't figure out if they should be downwards or upwards.

Hi,

My source has an optical Toslink sound output.
My DAC has ONLY optical ST inputs.

Do you know good Toslink to ST adapters or interfaces ?

Thank you very much

Hello, these days I have finished my first project with high sensitivity drivers and I wanted to show it to you.
I am very grateful to this forum since through it I have learned enormously, thank you.
The drivers chosen for the project are the following:
-Faital HF108 on B-52 PHRN-1014 Horn
-Faital 10PR320
-B&C 15 PS100
The midwoofer is housed in a closed box of about 14 liters. For the woofer I chose a bass reflex box with an approximate volume of 100 liters.
It is an active multi-amplification system commanded by the minidsp 4x10HD.
I am currently measuring the speakers with REW and adjusting crossover filters and EQ.

Regards.

_DSC5343-1 by Ivan Pelaez, en Flickr
_DSC5335-1 by Ivan Pelaez, en Flickr

[url=https://flic.kr/p/2jCoQgV]_DSC5338-1 by Ivan Pelaez, en Flickr
_DSC5351-1 by Ivan Pelaez, en Flickr
IMG_20200625_131638 by Ivan Pelaez, en Flickr
IMG_20200705_101158 by Ivan Pelaez, en Flickr
IMG_20200705_101333 by Ivan Pelaez, en Flickr
IMG_20200705_101517 by Ivan Pelaez, en Flickr
IMG_20200710_172850 by Ivan Pelaez, en Flickr
IMG_20200716_194107 by Ivan Pelaez, en Flickr
IMG_20200807_155736 by Ivan Pelaez, en Flickr
IMG_20200825_161242 by Ivan Pelaez, en Flickr

Hello all
I’m hoping to get some help on a project I’m looking at doing. I want to build a bench power supply for my LAB that will provide a variable DC supply at about 100mA from a 240v ac supply from my bench isolation transformer.

The reason for this supply is to test valve amp projects before building the final circuit. I wanted the supply to be variable from about 10v to the full 300v dc.

I have already constructed one design attached in image 1 below which for voltage control from 0v to 300v worked very well. However I have found that the output voltage can swing high when switching on as it is unregulated. I tried the circuit powering a heater element at 45vdc and when switching it on the voltage spiked to 55vdc then back down again. This destroyed the valve filament.

I am looking at the other circuit in image 2 which is a regulated supply. Has anyone built this and is it stable. What sort of output current could I get from this circuit.

I have an idea to build the first unregulated circuit for the plate voltages as this can be fairly unregulated, and then the second circuit for the heater elements at a lower input voltage about 80v ac.

Any help would be much appreciated I am a newbie to this I have experience with HV circuitry but not with designing the circuit.

Hello everyone.

I run a Buffalo-IIIsePro38 and run it with a Amanero-Cronus input. It sounds superb when I play music through my laptop connected via USB. However, when I use my Raspberry Pi 3 running Volumio (3.198) to play music a faint crackling noise is constantly present.

I already tried different power adapters, usb cables and settings in Volumio, but the crackling stays the same. Does anyone know this issue and can help out?

Best,
Stefan

Hi there, does anyone have a service manual/schematic for the Nakamichi MR 2 cassette deck? It's a professional version with balanced ins/outs and pitch control.

That's actually the problem, and yes I've cleaned the little 2K potentiometer, it didn't help.🙁

Thank you

Hi Folks,
Just wanted to let everyone know that we have managed to get a very good deal on a custom case for the Yarra preamplifier.

Here is a PDF CAD drawing:
https://www.diyaudio.com/forums/att...melbourne-db-buy-yarra-preamplifier_gx383-pdf



JPS64 came up with a superb mechanical and electrical design for this beauty. For a limited time, Hifi2000 (Modushop Italy) will be providing these for 100 Euro plus shipping (circa 20 Euro to USA). Once they have at least 22 orders placed, they will begin production.

You can read more about the details in the main Yarra preamp thread, but here is the GB interest list as it stands:

xrk971 - 1 case - USA
JPS64 - 1 case - USA
gary s - 1 case - Australia
Vunce - 1 case - USA
windwardmt - 1 case - USA
TungstenAudio - 1 case - USA
Meanie - 1 case - Singapore
Roundtoit - 1 case - USA
mordikai - 1 case - USA
afoor - 1 case - USA
Big E - 1 case - Canada
TboneAK - 1 case - USA
Sampsonite - 1 case - USA
jwjarch - 1 case - USA
batty - 1 case - Australia
MD_Stryker - 1 case - USA
jhofland - 1 case - USA
BEYoung -2 cases - USA (if possible)
ZUM911 - 1 case - Australia
Kokanee - 1 case - Canada
bk856er - 1 case - USA
BRN - 1 case - USA
urien - 1 case - USA

TOTAL = 24 cases

Click to expand...

If you are interested, you can place your order online directly woith Modushop and they take care of all the logistics of payment and shipping. We just did the design and marketing for them. A big thanks to JPS64 for arranging this sweet deal with Hifi2000.

YARRA PreAmplifier Chassis

I need to get some of these soldering tabs for making a crossover. I cannot figure out what they are called. see the picture, it's the part with the red arrow. Thanks to anyone who responds,

Hello,

I am building my first class D amp (5.1) and I am a bit confused about protection board.

I've used 3 stereo TPA3116D2 boards (Chinese one) and I also has bought 3x UPC1237 Chinese protection boards.

I am not really concerned about speaker protection, my main concern is the boot delay to avoid that big pop when I turn on the power.

First, I wired the UPC board as they are meant to be but as soon as I cranked up the volume, protection relay was triggered. It's seem to be caused by the fact that the TPA3116D2 board use a common ground. Vendor say that I need to use one protection board by channel.

So, I then try to only connect L+ and R+ to the UPC board and connect the two grounds directly to speaker. It didn't make the UPC to go in protection board anymore but left and right channel output the same sound.. I don't really understand why..

What can I use as a boot delay for these TPA3116D2 chinese boards ? I don't want to use 6 UPC1237 boards because of the space.

Thank for help.

Hello friends.
I have a MetroSound ST20 amplifier that has a "pop" sound when the power button is turned on, when the volume is turned down, the left speaker is still very low.
In your opinion, how to solve this problem.

I have a TEAC A-H500 amp which has some slight hum. Suspected a power supply problem; scoped it and found approximately 50 mV 120 Hz ripple under the load.

The 4700 uF filtering caps looked bloated so I replaced them with the new 5600 uF; however, both ripple and hum didn't go away. The attached picture shows this ripple for positive and negative rails going into power amp PCB after capacitors replacement; it looked the same way before.

The A-H500 amp is sort of high-end-ish; however, it was made in late 1990s and few components inside look cheap so it's possible they saved on a power supply.

Is it normal for amp's power supply to have such 50 mV ripples? If not what could be wrong, or perhaps it's some easy way to improve this PS?


Thank you.

Hi, has anyone got one of these? It's the phono stage from the Marantz model 7... or so the ad says. Comments? Experience?

Thanks!
(edit Feb 10 - added schematic provided by vendor)

Could anyone here could help download the block diagram, schematics and service manual from hifiengine.com for the Yamaha DSP-A1 model? Not sure if I could attach my receive email here but thanks in advance....

Hi all,

Since 2014, Lokcy_Z from China released his transistor curve tracer system, and that helps DIYers a lot. The tracer is powerful and inexpensive, and it seems there is no competitor at its price band.

After the production of first batch, the tracer was discontinued for many years. Until 2019, when Locky_Z announced to re-start the production. The new version has smaller formation and some improvements. The ADC and DAC are actually the same, as well as the software.

From early 2020, I got the new tracer and found out that the software have some bugs and poor English translation. Then, I started my work on optimizing the tracer software. Basically the terminology has been re-translated, so that it is much easier for international users. But translate the manual is huge task that I haven't done yet.

Right now, the software version is V3.5.30, in this version there are 2 important changes:
1. The color of curve tracing area has been change to white and blue, etc. This makes UI more friendly and readable.
2. The stamp of lockyZ's logo has been removed, and this helps when copying traces to clipboard and looks cleaner.

You can download the software here
or go to:
ElecFi Makers: LKZ Tracer ICT V3.5.30i

Any suggestions are welcomed.

WTB: TAD 2002. No, it's not a typo - I'm actually looking for TAD 2002 and not TAD 2001. Thanks.

I used to use Dale/Vishay for my standard 1/4W 1% metal film resistors, until, a few years back, Mouser starting pricing them at more than 50 cents each.

KOA Speer were a good alternative, decent quality and only 3 cents ea. in 100 pcs quantities.

Now Mouser has jacked up the price 300%, to 10 cents each. Oh, and they won't be restocked until February 2022.

Maybe that doesn't sound like much, but it adds up. I buy a lot of resistors.

/rant

What a title says . It doesn't have to work but it neededs to be in presentable condition . It would be nice if the seller could ship to US but EU destinations are possible ( Scotland and Poland )

Hello,

I am joining the forum to learn more about audio. I have made some boards in the past (ECG, EEG ) and wanted to get back into hobby DIY electronics.

My goal is to learn about microphones and ultimately redesign circuitry for the mic capsule from DIY perks and the MS Alice.

I like forward to my time here 🙂

Hi! Nice to meet you all! Mladen from Croatia here.

I contacted REL with no response.

So, got two T5s locally from a guy. I asked him if they were working fine before driving to him. He said yes. Drivers look new, cosmetics are pretty decent. I couldn’t try them because he didn’t have power cables and they were at his work with customers being there wouldn’t be easy anyway.

Came home, both are dead. No power whatsoever. Not a fuse issue (put new ones, didn’t work) Though check out these two boards. Both have the same kind of leak or whatever it is. Do you think this is the problem? Would it work if these were replaced? I am not good at soldering but I have the tools. Just would need parts. Though, it is pretty narrow there.

The seller says he will take them back but wanted to see if this could be the problem definitely and/or if it is worth the hassle. Thanks.

Hello,

After some solid state-years I just rediscovered the magic of tubes 😉

Here's my cheap re-entry, bought 2nd hand: Dynaco 6v6 Push-Pull tube amplifier – Boffin's blog

Time to tinker...

First off, I could really use some pointers for a good bias point. The schematic is in the link, but the measured voltages are much higher: 330V cathode/anode 6v6, 20v bias, 40mA/tube. Seems quite hot.

Any recommendations, keeping the cathode bias and UL arrangement? It sounds good already, but I'll dig up some better caps and tubes as well as rebuilding the PS. Running fine without nfb.

Thanks,
Simon

I purchased 2 pairs of these maybe rather too prematurely and it would seem I dont have the room for them.

I have the data sheet to share and I shall attempt to link to the thread I started about these.

Edit....link here...
Uses for these Seas 6.5" proprietary drivers

Drivers are brand new unused. One has had a wire soldered on for testing.

£25gbp per pair.

Thanks

Hi everyone,
I have a plan to design an active 3-way using DSP. My reference is Genelec 1238. The speaker will be studio monitor for my upcoming studio.

I have success with 2-way system before using B&C DE250, B&C 12PLB100.

But 3-way is something more challenged that I am interested to try. Due to the unique waveguide of Genelec 1238, I dont think I can find a similar waveguide so I will rely on available parts on internet.

My general purpose is a speaker with:
1. High power handling to use as a main monitor (2-5m listening distance)
2. Accurate and effortless transient response in the whole frequency range
3. Using waveguide at least on HF unit to control directivity
4. Can reach down to 30Hz in-room effortlessly
5. It will be flushmounted in heavy brickwall
6. It can play really good at even low or medium SPL (75-95 dB SPL at the listening position)
7. Due to the room is normally small 20-35 m2 maximum, the speaker will never need to run at full power

My driver choice currently is:
1. 1" Compression Driver: B&C DE250
2. 8" Midwoofer: B&C 8PE21
3. 15" Woofer: This is the unit that I am not decided yet. My current selection list is: B&C 15TBX100, 15NBX100, 15NDL88.
4. Waveguide: I did not finalize on WG choice, too. My current plan is SEO-8 or SEO-10

Could you please help me to choose appropriate drivers and waveguide?

I prefer B&C drivers as I have great experience with them before. My budget for LF unit is around 200-300$. I prefer woofers with high motor strength, low enough moving mass, coated cone and has demodulation ring. I really need the dry, tight and focused LF transient sound.

Thank you very much.

Was looking at a Kenwood car amplifier from the 90s. The output stage consisted of a pair of 0.5 A MOSFETs and 20 MHz Sanken BJT output transistors.

Looking at the data sheet, the input capacitance is highish (120 pF) and the equivalent fT only about 15 MHz.

https://www.web-bcs.com/pdf/Hit/2S/2SJ76.pdf
I can see the attraction of not having beta droop loading the VAS and possibly some positive TC (not sure this is the case here) stabilizing the idle current, but in terms of bandwidth and nonlinear capacitance, I suspect many bipolar drivers will be superior. Your take?

I see there is no thread on the Calaf here yet.
Thought I'd do something about it 🙂

I have seen totally 4 of these amps.
They have a very failure prone adaptive bias system.
One had tubes on the input...rest only had the PGA2310 volume control chip.
Sound is decent and there is plenty of power.

One of the calafs had "only" a bad solder joint on what is called the "distortion board". Rest had one channel smoked.
The distortion board is the size of a stamp, SMD, 4-layers and limits BIAS in idle.
Consonance does not provide a schematic of this board, for the others they do.
It is quite impossible to fix.

One I got so tired of that I built Krell KSA-100 boards in it.
I think this was an improvement from the Calaf circuit.

During the weekend I tried replacing the distortion board with 5 1N4148 diodes and a 100ohm trimpot.
Need to bias the amp to about 0.5A to reach -90dB dist. levels.
Originally power transistors are biased to only 3mA each = 18mA.

I am happy with the sound of this modified Calaf. Bias is not easy to adjust though. Started amp at 300mA and after some time it was over 1A. After reducing bias a few times it seems quite stable at 500mA...but I can only imagine what the warm up time will be next time I switch it on 🙂

If someone needs schematics or spare parts I can help 🙂
I'll try to post some photos of my creations too.

hi - (very 'basic' q's - very grateful if anyone can bare to answer, thanks.)
I'm looking into experimenting taking bottom end off my mains (8'' 3 way; ellam flex 3) so just my sub is left to the 'subsonics'. I've heard a good way of doing this is simply via a input cap to amp - NC400s (inZ 104K).

Q; I'm running fully balanced so presume a cap is required on the + and - ?? (as i've suggested in diag)

an online calc has given me the values on pic - just checking i haven't made some schoolboy error? looking to roll off from 40hz down initially - its easy to cheaply add another cap to increase this value and push the point lower. (thinking of la clanche sig path caps)

p.s. apologies if i'm using wrong terminology 'c.30 Hz' as in 'circa'

many thanks if you can assure me I am on the right track or otherwise

R

Is there anywhere I can find more detailed dimensional drawings of the Galaxy chassis. Trying to figure out if my stuff will fit a particular chassis.

Not sure what these are called .

Anyone know where I can purchase these or know of a good alternative?

I just noticed that the symmetry I’m working on these are missing

Hi

Not sure if this is correct subforum, but, I have two questions and here they are...

I have a transformer from dead onkyo tx-nr414 that I want to reuse, now, it has 40/0/40 and 10/10 leads. From 40/0/40 Im going to power mosfets in half bridge and I want to use 10/10 for powering everything else. My question can I connect GND connected to center tap of 40/0/40 after rectification to GND that will be created after rectifying 10/10?
Second question is, I want to provide some protection to speakers and I can see onkyo has relays for that purpose but they are controlled from MCU, is there some standard way to provide overvoltage and overcurrent protection? Over voltage I know how to do but for overcurrent I would have to put some current sensing resistor in speaker path and Im not sure this is the correct way.

Thanks.

Hi all,

Sourced a UK model which has 220v and 240v operation. For it to work in US I used a step down convertor of 110v. Looking at schematics am confused and wondering if this would be as easy as rewiring or not. The transformer part is the same but I see the switch is different. Any guidance if I can wire it to 110v. The relavant part of the schematics is atached

Iam planning to use 6c45 as a input tube for a ss amp SE.
But I Wonder how Hard I should driver it.
Im thinking 20 to 30mA , or is it any benefit
In going to 40mA?

Subject says it all.
Thanks,
George

Wharfedale D310 mini monitors in walnut finish.
Almost brand new, only a few weeks old. About 50 hours of play time.
Will come with everything it came with when new, including factory packaging, owner's manual and grilles.
No cosmetic blemishes, they are as new. From non-smoker household.
Surprising amount of bass in my 16 x 10 listening room.

$100
Will ship UPS Ground for $25 flat anywhere within lower 48, with tracking and insurance.
Thank you for looking.

Hello,

Still on my journey to recover long lost knowledge...

This time I am analyzing various circuits to understand how they are grounded.

Today, this one:



The plate under the PCB is metal.

Here is what I see:

• The IEC inlet ground tab is not wired to the metal plate.
• Input signal ground doesn't appear to be wired to the PCB.
• (unrelated to grounding) The headphone output jack appears to be wired to the preamp outputs.
• (unrelated to grounding) Input signal wiring bypasses the PCB.

Now, this design/build appears to be a newer version of this one:



This build seems to wire input signal ground.

Now, the other side of the board:



I see a star grounding pattern. And that center point connects to the bottom metal plate via a standoff.

Finally, the schematics:



My questions:

1. Why should they not connect the IEC inlet ground tab to the bottom metal plate?
2. How could they not connect the input signal ground to the PCB? (???)
3. (unrelated to grounding) Is it OK to piggy back preamp out on the headphone out?

As usual, please forgive my ignorance, I am just trying to figure out the best practices, but and I definitely have much to (re)learn!!!

Also, if there is anything else that catches your attention in this circuit/build, please do share.

Hi

I have just bought a quad of premium grade Shuguang CV181 treasure tubes.

I see there is a classic grade available also, is there any way to tell the difference between the two grades?

It is my understanding that the premium come in at least pairs in a fancy box and that the classic grades can be bought singularly in a not so fancy box.

Also I see the ones advertised on eBay which are sold singularly have three upside down "A" markings as shown in the image below

https://www.aliexpress.com/item/4001028661529.html
Whilst those sold as premium having the writings on them as shown below;

https://www.hotroxuk.com/psvane-black-treasure-cv181-z-gold-grid-matched-pair.html
Can anyone confirm that the ones with the three upside down "A" markings are classic grades only?

Any help greatly appreciated.

My Zero Zone Preamplifier has a strange hum problem. I swapped tubes, dropped the AC ground, using a test probe tried to rearrange ground connection. Only does it on Right channel. Is not volume control dependent. Does not increase as volume is raised. Same hum whether source connected or not. As you can see in video, hum increases only on this channel as pencil is introduced. Any ideas?

YouTube video:

Login to view embedded media

Hello,

I have TRIBUTE transformers as follows:
INTERSTAGE FINEMET CORES 1: 0.8, current 20ma, 130Henry, 639 ohms, 307 ohms (2 pieces)
SE LINE OUT FINEMET c core, Prim. imp. 20K - sec. imp.790R (4: 2.5), current 10ma, prim L 160Henry, 540hms, 380 ohms (2 pieces).

Please can help me to determine the approximate value for the listed good transformers.
Thanks in advance for your reply.

Best regards from Croatia
MILIVOJ FAFANĐEL

It’s been a while since there’s been a “from Wisconsin” build thread, so I thought I’d get another one started.

In this discussion, I will be documenting the build of my “Best Thing since Sliced Bread” panel-mounted buffer provided by @xrk971 at XRK Audio. It is a buffer stage that can perform single-ended to balanced conversion and back. Since I’ve been trying to build a system that is balanced when possible, this was a cool tool to have in my toolbox. Details on the product can be found here:

https://www.diyaudio.com/community/threads/btsb-buffer-se-bal-to-se-bal-buffer-gb.358142/

I bought four PCBs and enough parts to create them for an upcoming project that will have four buffered inputs and could allow for either balanced or unbalanced sources. After a thorough inventory and marking of parts, I embarked upon a journey of SMD unlike any I’ve yet to experience. I read through the entire discussion above, closely reviewed the circuit boards, and the decided how I was going to attack the build.

Can the 15″ SB42FHCL75-6 / Honeycomb play up to ~500 Hz, crossed over to a suitable midrange unit in a 3 way layout?

The FR seems good enough (maybe the 1.5 KHz peak will have to be notched out...?)... It is called a "sub"woofer by the manufacturer, which leads me to think that it is meant to play below ~100 Hz only...

Hi all,

I have already done this before, but would like to know if there are any drawbacks of reducing the secondary voltages of a toroidal transformer by taking off a few turns off the secondary windings? I need to drop the secondary voltages by 2-3 volts.

My vinyl equipment consists of a modified Lenco turntable and a Hagerman Cornet3 phono preamp. I have had a long standing grounding issue that is presented as noise from the speakers when I touch the tonearm. As far as I understand the reason for this is quite simple, the power supply that came with Cornet is a wall wart type, with a 2 prong connection. Meaning there is no ground. I have checked that I have continuity from the tonearm all the way to the mains connector on the phono amp.

I must be missing something, how should I get this grounded if the power supply doesn't have a ground pin?

I'm almost done with my TU-8900 and I ran into this problem. Pretty sure I seated the volume shaft onto the switch. Can anyone advise me where I went wrong and where to go from here?

I just received a brand new pair of Alpair 10 Gen 2 speakers. Not sure what to do with them....Open Baffle?...T-Line....Use in 2Way? Anyone have any suggestions?

Here are the specs:

https://hificompass.com/sites/defaul...gold_gen.2.pdf

My Crosley C100 has a ground loop issue and frankly between its built in preamp always having problems and the fact that I have to adjust the speed (usually in the negative 4 to 5% range) I'm kind of over it

Looking for a ~$200-300 turntable that can deal with my utility's crappy power quality (last I measured was about 128VAC and there's regular flickering) and adjust to the correct speed on its own. Honestly my vinyl collection is pretty old and ratty and this turntable is in the kitchen so I don't need the last word in isolation or sound quality. Any suggestions?

The amplifier is Audison vrx 1.500.2. I've rebuild the PS section .Nothing shorted or burnt in output section.
Amp starts fine, green light, after 3 seconds RL1 (relay 1 which is nais tq-12v), or something around it starts multiple clicking, buzzing and producing awful sounds and I mean loud sounds.
Amp gradually draws more and more current and I look quickly to turn it off. Can't find anything heating up.

Removing RL1 (relay 1) nais tq-12v - removes the awkward clicking and amp draws 1.3A stable.

I've found partial schematics for the earlier revision Audison vrx 1.500 (not the Audison vrx 1.500."2") in the thread over here:
https://www.diyaudio.com/community/threads/audison-vrx-1-500-2-clamps.299921/
Am I being right that this relay turn on the output stage ?

Any ideas what to look for ? Rail voltages are fine +-70v.

Hi Perry! How you doing? I have a question Sir. I have and old infinity 611a amplifier. Amp is working good and no problems I had it installed on my car but couple of days a go opened it to clean the internals usually i do this from time on time with some computer air can.Well I find that 2 capacitors are swollen so before they blew and make it worst I plan on replacing them one is 10uf and the other is 33uf both BP and 100v so I was reading this that you posted on this thread.


Hifonics mono amp with non polarized capacitors brz1700.1d


"The series caps EACH have to be able to withstand the full rail voltage. One is always reverse polarized and when reverse polarized, it drops very little voltage. Virtually all applied voltage is applied to only one cap at a time. In practice, in the amps that use reverse series caps, the individual caps are rated for 2x the maximum voltage that will be applied (2 series 200-250v for an amp with ±80-100v of rail).

I use 10uF film caps to replace 10, 22 and 33uF BP electrolytics."

Well the question is can I use a 10 uf film capacitor to replace both of the swollen caps? I see you recommend a panasonic 10 uf 250v 105° to replace the electrolitics, this same cap can be used to replace a 22uf 250v BP capacitor too? Last question is for a hifonics amp capacitor.

I want to make an instrument amp with a 2 channel amp board that I have, that will drive two speakers.

I would like to have a single 1/4 jack input, that can accept either:

1) a mono 1/4 jack cable, in which case, the signal gets duplicated to both channels

2) a stereo 1/4 jack cable, in which case, each channel

Is there a way to wire a 1/4-stereo female connector that can do this ?

I know it can be done with 2 seperate 1/4 inputs (one stereo and one mono), and a switch, but it would be nice if it could be done without a switch, and just a 1/4 stereo jack input.

Picked up another p1000 used and its got seriously noisy gain pots. Did the basic cleaning and they're better but noise is in and out now.

Can anyone point me to some decent replacements? Doesn't seem to be much for info floating around.

Amp came in with a blown output I removed the output and tried powering the amp up .

On the power supply fets I get the following voltages .
Gate :4.81
Drain:13.81
Source:5.51

Any ideas why I have 5 volts on the source leg ?

Beautiful pair of Audio Note ANJ LX’s. Olive, ‘premium’ High Gloss finish. ‘Mint’ factory condition. Fully boxed, with Black Gloss AN stands and all accessories. Price is £3600.00, collected from Knaresborough, North Yorkshire, U.K. No couriers! Thanks for looking.

Hello,

I am designing small "chatting box" for an artistic performance. The box is triggered when someone walks close to it. It uses infra red PIR proximity sensor. When triggered, the box outputs various sounds : voice, music, sounds effects. I use a Teensy micro-controller (similar to Arduino), a 5V lithium battery, a class D 3.2W mini-amplifier, and a compact full-range 4 ohms car loudspeaker (for tests). Everything is working, but I try to optimise the box to get the the loudest sound as possible. I need to find the right loudspeaker :

• 4 ohms (or 8, but amp is designed for 4)
• full range. Bandwidth is not important here. I don't need big bass or extreme highs. I focus on meds + high meds.
• as small as possible : 2,5" or 3"

What kind of speaker would you recommend ?
What do you think of sound vibrating triggers ?

Any guidance welcome !
Emmanuel

Hello,

I am building a Rod Elliott Phono stage for my setup. I am using the P05 power supply board and the P06 phono preamp board. Rod specifies that the P05 needs an AC supply from between 3 and 25V. I found a 16V 1000mA AC power pack from Jameco for this purpose. Here is the Link to the Jameco AC adapter. However I am having a hard time understanding the grounding as noted within Rod's schematic. On the P05 board there are three inputs, AC1, AC2 and ground. However any AC supply I have seen doesnt include a third ground wire, just hot and common. What am I supposed to connect to this grounding input?

Im cobbling up a universal tube preamp with the maida regulator. Calling it universal for the fact that the gain stage will be modular and differenr circuits can be tried on a single board. But as such the psu will have to be fixed in its voltage range. So id like to ask you what b+ voltage should i aim for that will make the pre as 'unuversal' as possible? 😁

Hey guys, I'm not sure if a "want ad" is allowed in this section, but I figured most of you probably don't make it to the general FS section so I thought I would risk the wrath of the Mods and ask here. If this is not allowed, I apologize in advance, I will be happy to repost elsewhere if need be.

This isn't strictly a "wanted" post, but I am looking for a DLM4500, revision 3 or 4. The board does not have to be working, in fact I prefer one that you have lost hope in.

Here is the deal, I decided a while back when I took my bad driver board apart for pictures for another guy that it might not be to bad to reverse engineer this thing. I have started with the bad board from my Autotek MX1500.1 and am making progress, however, I found what I suspect is the problem with my board and I would really like to reassemble and test in my amp. I'm leery to keep pulling this board to continue mapping it and drawing it in eagle.

When/If I finish this, I will post up the completed files. With any luck I may even be able to cut replacement boards with my CNC Bridgeport mill... That is the hope anyhow.

So, what have you got? I don't want to spend a ton of money, but I will happily buy a complete blown amp if the price is right.

Thank you all!
Jason

Hello everyone,

I am attempting to repair an old car audio amp. it is an Earthquake T2000W/4
and I managed to find the schematic: https://drive.google.com/file/d/1zqfWyQ9OT4StDlfMfhDePenB9qFjxkkN/view?usp=sharing

When I received the amplifier it was in very bad condition, left out to the elements.
I cleaned the board and replaced all the power supply FETs as they were blown/missing.
Also substituted in a rectifying diode pair from another amp which was missing.
replaced the blown blade fuses. and checked all the output BJT's. the BJT's all seem to be ok and unharmed.

The problem is I power up the amp and when I try play music it is extremely distorted and scratchy. ( On all 4 Channels )
Also the protect light is permanently on.

I tried removing all 8 BJT's and the protect light is still permanently on.

I scoped the power supply and the output is 50V DC and looks clean.

I'm not sure why the protect light is on and why the audio is so terribly scratchy and crunchy.

Please let me know if you have any suggestions.
This is my first post here and I'm quite new to the scene so please excuse any informalities.

Regards,
Alex

One of the more interesting acoustics discussions that I haven't seen to date is the measurement of the contributor's room RT60...reverberation time, typically stated for -60 dB decay from the initial pulse. I really haven't seen posts of measured RT60 curves for listening rooms on audio forums, in general. This would be a good place to post them it seems. Statistics would be difficult to gather since the plots are not scalar, but a collection of plots in this thread might be useful to others.

I once did a study of listening room sizes (reported here and here) and found that there seemed to be a correlation of where you live geographically to the room size (no surprise there), but for the survey respondents there seems to be a larger size than I would have guessed (ave. length - 21.1 ft, ave. width - 18 ft, ave. height - 9 ft). This indicated to me that many that have smaller listening rooms weren't reporting on the survey.

One of the more interesting comments that stimulated this thread on RT60 was from REW help on the subject:

For domestic listening rooms and recording studios with volumes of less than 50 cubic metres (1,800 cubic feet) the recommended RT60 value is 0.3 s. For larger rooms, up to 200 cubic metres (7,000 cubic feet) the recommendation is 0.4 to 0.6 s. In both cases the value should be fairly uniform across the frequency range, though it will typically tend to increase at lower frequencies.

Click to expand...

In the spirit of jumping into this, here is a typical RT60 plot taken from a REW measurement in my listening room (approximately at the listening position):



I consider my listening room to be just a little bit "live" vs. what you would experience in a typical home theater room, but much less live than many lofts and hard surfaced dens and living rooms without any treatments. The room volume is 152 m^3 (5500 ft^3).

Chris

Hi All,

I am interested to hear about any user experiences or advice regarding output transformer impedance and B+ combinations for KT88 singled ended ultralinear operation.

My current amp is running EL34's with a 5k transformer right on the limit, with 412V across the tube and 60mA bias. I am very happy with the performance.

For the next amp I was contemplating running KT88's with a 5k transformer, about 400V across the tube and 100mA. However, looking at the KT88 datasheet it seems this tube might be most comfortable with 2.5 to 3k and 250V-300V across the tube.

I'm intending to run local cathode feedback on the output stage.

Interested to hear what you're all running.

Also can someone please explain the significance of the dashed lines on the curves below? I take it 425V is the highest voltage I can run across the tube and ther other one is presumably showing the grid 2 dissipation limit under some conditions I don't fully understand.

Many thanks,

Greg

I I'm selling last 8pcb of excellent Apex A40 audio reference power amplifier.

Pcb specifications:
- 70um copper (2oz)
- 1.6mm pcb thickness
- red solder mask
- white silkscreen
- hask pads
- pcb drilled
- pcb is drawn for mt200 devices but to264 is compatible.

Price for 2pcb is $25 plus shipping (will be calculated for each country with tracking number).

Payment will be with paypal.

Here is picture of boards and completed board..bom with schematic in pdf will be delivered to buyers mail.

Hey all,


It's been a long time since I've done speaker design. Back when all that existed was a giant spreadsheet to figure out baffle effect, etc. However, I've recently relocated to an apartment, and am investigating ways to create some bass response without annoying the neighbors (if this is even possible).


The units seem insulated pretty well, which is nice. The system setup here is pretty low-key. Some transmission line Dayton towers, and small Dayton surrounds.


To fill out the bass I'm curious if anyone has any thoughts on a small, 8" subwoofer placed directly behind the main viewing seat, potentially at head height, and potentially open baffle to reduce transference.


I doubt I'll be able to get the "feel" I would want, but am hoping to get at least a bit more low-end out of things.


Thoughts or ideas?

Hi, I am going to build an RFI mains filter and am using X and Y rated capacitors, and wanted to check 100% that I am not missing any information on the +/- orientation of them before I make the installation.

This is probably a stupid question but I sort of expected to find some guidance on where the + would be when installing but both of the products I have selected, but they seem to be with out any orientation requirement or guidance.

Here they are.
https://docs.rs-online.com/4e61/0900766b8162aeae.pdfhttps://docs.rs-online.com/2181/0900766b8171cbeb.pdf
This is the circuit layout, it's an old design and well established approach.

Any experience or help much appreciated!

Can anybody advise me of the crossover components, values and implementation in the Royd Minstrel? Photo's would be great but any info on the layout is welcome. I believe there are is no low pass and the high pass is a modified first order but I'd like to know what the modification is if possible. 😕

Jae

Hi all,
Looking for a circuit or service manual for an Akai am-u33. One channel is dead

Hello all,
I have little experience with other than hifi products and drivers, so I was hoping somebody had some experience or advice for me. I have installed a rather large sound system, build into walls and closet, so it does not take up any space and has little effect on the interior since you only see the speaker grill in the walls. Its not a hifi "sweet spot" system, but something that fills the hole house with decent good soundqualtiy and plays loud (around 125 db between 30-15000 Hz). For high and midrange I am using high quality drivers from Seas or DynAudio or B&W, most 5.25" or 6" midrange and a 1" dome. But they all keep on burning up (voicecoils are falling apart and at 2 occasions destroying the amp in the process.) The amplifiers are not clipping, and there is no passive crossovers anywhere, I use a 10 channel dac/active crossovers and one amp/channel pr driver. My signal input is not clipping either.
Where should I look for something that can play loud and handle decent power? No experience with PA drivers or Horns or compression drivers, is that the way to go?
Any help much appreciated, I have replaced 10 midranges and 6 tweeters in the last year or so.

(info: The 6 wall speakers are set up like this: tweeters (3000-18000Hz with 50w or 100w amplifiers, for midrange (250-3000 Hz) 300W and for midbass (80-250hz) 500W and finally a single "house sub" with 2x15" woofers with a 2000W amp bridged in 8 ohm playing 30-80Hz. I have measured all amps and the rating is fine, continuous output with a sinewave and max 1% distortion, and they all had some dB headroom left. ). All crossover slopes are mostly 96 but tweeters are 24 dB pr octave.
thanks
Best regards Simon

So I unknowingly bought a dead-ish Adcom. Unfortunately, it should have been sold as parts and I paid pretty much the full used market value. The seller has ghosted me. Well lessons learned, time to make some lemonade out of this lemon. I had him test the outputs for DC offset, but unfortunately it was an out of the back of a car deal, so I couldn't test it further.

The amp will play music, but horribly distorted on what seems me is peak values, but how much gain is applied, doesn't seem to matter. Both channels are affected.

DC offset at the speaker terminals is -14mv/-50mV with inputs open. I've checked the bias values on each output device and they seem settle out nearby the nominal 16mV (range: ~15-17mv - one reads 20mV). Some are a little low, some are a little high, but nothing really sticks out. The power supply caps are old, and suspect some issue there, a drain test says some are definitely more than 20% out of spec. Rail voltages are about 83V

The input board on the pro model has balanced inputs (which use an opamp to convert to unbalanced) and TRS jacks for the unbalanced inputs. Given I don't have TRS adapters, I have not tried the unbalanced inputs.

Where to start?

• Input board -- https://hoppesbrain.com/product/gfa-555-mk1-input-board/
• Driver transistors
• PS caps

https://hoppesbrain.com/adcom-faq/#What-are-the-most-common-issues-with-the-GFA-5x5
https://hoppesbrain.com/adcom-faq/#Bias-Adjustment
https://hoppesbrain.com/adcom-faq/#How-much-DC-offset-is-normal
https://hoppesbrain.com/adcom-faq/#...r-supply-capacitors?-If-so,-which-ones-to-get

To replace the input board, it will be a pain, since there isn't a drop in replacement since it is the pro version which is mounted by its balanced inputs. I've considered replacing the PS with a diyaudiostore universal PS V3 when they become available. This would open space to mount an input board onto the floor of the unit.

The universal PS is CRC, with 4 caps per rail with 2 each side of the resistance. I think I could use 7500uF 35mm 100V rated caps snap-in type caps and just squeak in what will fit onto one of these boards. It would allow me to significantly reduce the footprint of the PS. Drop in replacements were about $77 CAD each, so significant cost savings and a better PS.

Comments?

Hello all. I found this pearl looking in old magazines at worlradiohistory.com.

Opinions?

I am in the process of designing a new phono pre and would like to use the 6c45p tube. I had build a earlier version with R load but after much research have found out that it is not optimal.

One issue that I want to overcome is the tube ageing which lowers transconductance plate resistance (Rp) rises. So as the tubes age the filter is no-longer being fed from the same impedance and the frequency response will impact the LCR network. To minimize this I want to use the LL1671 with 4:1 step down. I think this will minimize the Zout divination as the tube ages. The overall amp still has 60dB gain so it should be good.

I also plan on using the K&K High Voltage Shunt Regulator Kits to load the transformers. Not in the attached schematic yet.

YOU GUYS ARE EXPERTS PLEASE LET ME KNOW IF THIS IS A GOOD IDEA OR NOT? or how I could improve the design.

THANK YOU

A working 3 way project all new drivers. Both the tw and mid are 92Db and the wf is 88Db.
Looking to simply boost bass it seems to lower the sensitivity of the mid closer to the wf would help.

Installed a LPad in circuit was not successful except to attenuate the high frequencies of the mid. No noticeable bass improvement.

Thinking now to just place a resistor on the mid. It would have to handle about 100 watts so a wire wound would be necessary. Researching has not given me any help selecting value. Hoping I can get some here.
Thanks

Brand-new FS Khozmo 64 steps relay-based ladder type attenuator 5kOhm stereo with a remote option upgrade.

I have ordered a quad version attenuator however due to a mistake made by Khozmo a stereo version was instead sent to me.

Before I send it back to Khozmo, I thought, to save hassle, I will ask here if anyone needs a stereo one.

Current RRP price is £242 + Customs Duty. I will let it go for £220 + postage.

I am happy to share details of the purchase, please let me know if you are interested.

https://khozmo.com/64_steps_relay_khozmo_attenuator.html

I am selling my Locky_Z curve tracer board. The board has never been used. See attached photo. For more details on the Locky_Z board see this thread.

Please send me a PM with your offer if you want the board.

The many resistor reviews and comparisons I've read usually include Dueland, Mundor, Caddock and a few others but I've never seen the Dale wirewound power resistors included. Is this type of Dale resistor considered not appropriate for crossovers?

For sale new unsoldered Hi-end pure COPPER FOIL COIL in WAX. German production Audio - Tschentscher
2pcs 1,3mH - AWG 16 (0,42ohm) ....19€
2pcs 1,5mH - AWG 14 (0,336ohm) .... 24€

I have just received my grandfathers speakers and receiver. I am so excited to have these in my life. I hooked it all up and it doesn’t sound great. They have been sitting in storage for while and I think the speakers are from mid 70’s. I took off the sub so I could get a look at the crossover and this gasket broke apart.

Any recommendations to get these speakers sounding better? I am excited to get these but feel overwhelmed with getting them sounding good. I am think that maybe swapping out capacitors and L-pads from what I have read may be a good place to start…

Introducing the PecanPi® Streamer Ultra!!!

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• The front of the unit will feature the 5", TFT, 800x480 pixel display.
• The back of the unit will have all the connections: Ethernet, USB, XLR, RCA, etc.

Dimensions: 190 x 120 x 95mm (7.5 x 4.75 x 4in)
Weight: 2 to 2.5kg (4.4 to 5.5lb)

I am currently taking $50 deposits as a reservation for these. Full info here:
https://orchardaudio.com/shop/ols/products/pecanpi-streamer-ultra

The PecanPi® Streamer Ultra will retail for $850. Everybody who makes a deposit will get $150 off the retail price once the product launches. The deposit also guarantees that your unit will be the first to ship in time for the holiday season.

See images in attachements.

Hi all

I'm new on here and I'm hoping someone can help me. I bought (maybe foolishly) a Boyuu EL34 A9 amplifier as a kit. I'm used to building electronic kits with good plans but the Boyuu comes with a schematic wiring diagram only which I'm finding difficult to interpret. There are very few photos of the internal wiring of the A9 availalbe. My main problem is the connections to the two front pots; then the rear input/output panel and, importantly, the mains input.

Does anyone have the ability to post/send photos of the inside of one of these amps? Or does anyone know someone that can build it for me for a fee?

Thanks in appreciation of some help.

P