Hello all,

I have been working on a phono preamplifier and everything seems about right. But I noticed some occasional harshness in high frequency range.
For example some accented hi-hat of the drums or some high frequencies of vocals get distorted. I checked the PCB and also the RIAA response with measurement software and everything seems about right. The gain at 1KHz is 40dB.
Any thoughts or comment on this?

View attachment 1088418

Hi everyone!

I'm in the process of replacing the crossover parts of my Cabasse MT 3 Jersey speakers with better ones (hopefully).
The cap replacement way easy, so I bought a LCR meter to measure the coils and now I'm stucked and need your help.
The coil for the tweeter circuit has 2 sets of wire strands and are marked in the pictures bellow as A, B, B1 and C. On the PCB, B and B1 are soldered together and marked as B.
On the continuity test, A-B is the first strand and B1-C is the second one. When measured, A-B shows 0,000 (not null), B1-C is 0,211mH and A-C is 0,580mH (B and B1 connected).
The DCRs are:
A-B - 0.6 ohm
B1-C - 0.7 ohm
B-C - 0.9 ohm (B and B1 connected)
A-C - 1.2 ohm (B and B1 connected)

The wire(s) used for this coil are 0.25mm in diametre.


What values (mH, ohm) shoud I take into considerations when searching for the replacement coil(aircore)?
What's the purpose of a 2 wire strands(3 ends) coil in this crossover?


Thank you very much!

Here is a 6 Watt Amplifier.
EXAPP is it called.
Uses EXICON Lateral MOSFET. Class A Push-Pull.
Will draw 18+18 Watt.

Distortion is low.
Bandwidth is okay.

Hi Guys
I was recently testing a 100w power amp (AMP-70 https://www.diyaudio.com/community/threads/winfields-100w-dc-10mhz-1000v-us-amplifier.287023/) and according to JD's patch documentation, I built a flywire on the B side of the board
As described in the picture
Now as soon as the power is turned on, Q27, Q27, Q28, Q33, Q34 will be shorted
I don't know if I need to disconnect or jumper the wires there in advance?
Also, is this J7 jumpered correctly?
Can anyone help me or give me some tips, thank you very much!

Dave Hill founder and designer of Cranesong gear passed away the 3/2/23.
We lost one genius designer of analog audio.
Rip Dave, it's been a pleasure to met you and use your gear, you'll be missed.

Hi all. Recently I replaced all capacitors in my quite dated Klipsch RSW10 subwoofer. After completing the replacement, I plugged in the power cord, without any input connections, with the sub-woofer's on/off switch at OFF. Immediately, there's the loud buzz. I then reverted back to all the original stock capacitors but the buzz still came on. I did checked the two large capacitors (which happens to be snap-in type, 4700uF) and the measurement came close to what is stated. So they seemed to be in good shape. When I did the caps replacement earlier on, I used the radial type of caps for these two large caps, not snap-ins. Any idea what could be the problem causing the buzz? Thanks.

I am looking for a single 2SJ18 with a rank of 5 to repair the left channel of my Sony TA-4650. Don't ask how it broke 🙁 Pure idiocy on my part.
Any help appreciated. Hope to avoid Chinese fakes from fleabay.

Hi all -

Looking for a UTC H-1709 if anyone has one! Almost the last piece of the puzzle for me.

Thanks,
DH

Hi there,

I have a couple of early 1970s 12" bass drivers - Philips AD 1256/W8 and I'm looking to do my first speaker build. I had orginally intended to build 2-way speakers using some other preloved tweeters (Electro Voice T35), but there would have been a large gap in the middle of the freq spectrum. The DIY audio forum was super helpful with this.

So, rather than spend more $$ and build a 3-way, I'm thinking of using the 12"drivers to build subs instead, and pair them with my current hifi speakers - Celestion Ditton 33 (also 1970s, 8W). According to WinISD, the Philips drivers will extend down to mid 30s Hz in an approx 100L sealed enclosure. Given that I'd be pairing the DIY subs with full range speakers - and to avoid really expensive crossover components - I'm thinking of a crossover freq of about 500Hz.

This post is just to sense-check my idea:

• does this approach make sense? Is done often?
• might there be any issues crossing over at 500Hz? (Note I'm planning to build and run 2 subs in stereo)
• any other issues/challenges?

I see this exercise very much as a trial run/learning experience - but I would like to avoid any obvious errors and build something useful at the end of the day!

thanks in advance,
Steve

PS there are some more parameters/photos of the drivers in my post here: https://www.diyaudio.com/community/...sing-t-s-parameters-for-vintage-driver.396183

Hi Friends,
I'm looking for genuine pairs of 2SK60 and 2SJ18 VFETs for the Sony TA-F7B. Hit me up if you have any spares 🙂

I have a new to me MB-1s that has an odd tray behavior. It will somewhat randomly close immediately after opening, sometimes after a few seconds or longer. I do have the service manual but after a review nothing jumped out as being responsible for this. Maybe the load/unload switch is the problem?

Hi All,

My name is Alex and this is my first post.

I have very basic knowledge of electronics, but 25 years ago, I built my hi-end speakers from a well know company who published their own kits.
The speakers are 3.5 ways: 2 woofers + 1midrange + 1 tweeter ( 2 x front ported)
The cabinet was very difficult to make, in fact, I was helped by a wood craftsman, and the speakers were lacquered.
The company who supplied me with all the components, suggested to make a different (and more elaborated) crossover, compared to the one proposed in the original project.
Image is attached.

When I listened to the speakers the first time, I soon realized that the high frequencies were too bright, and therefore they suggested to change the value of the resistor on the tweeter from 1.0 to 1.8 Ohm.

That worked fine.
However, since then many things changed in my gear, I also moved to a new home and I have a much bigger room.

As a result, I find the need to apply a further cut to the high frequencies, and wanted to ask you if the way I should do this is the same, (increasing the value of the resistor).
If that is the case, which value should I use for the new resistor?

Thank you!
Alex

Looking for 1 or 2. Thanks

So I am referring to DACs that employed op-amps, like many Aliexpress DACs. Many of them have NE5532. People tend to talk about op-amp rolling their headphone amps. But how about DACs ? Will upgrading Op-amps in a DAC change the sound for the better ? Thanks.

One of the things I frequently see are people saying that they cannot ship their floor standing loudspeakers and must have local pickup. That shrinks your potential buyer pool to almost nothing. Your speakers sit for months and years, and when you do sell them, you get pennies on the dollar for what you paid for them.

I recently moved to Hawaii from the mainland and had to pack my custom made loudspeakers, which are fine furniture. I had to separate the top and bottom piece of each loudspeaker, so I did four cartons in all. Here's how I did it and you can too. You're going need the following materials found at Home Depot.

• furniture wrap. It looks like a giant roll of Saran Wrap.
• Bubble wrap. Get the kind with big bubbles.
• Packing popcorn

Next you're going to go to a place that sells packing cartons. Many long term storage companies will sell packing materials. Get wardrobe cartons. They are very thick and strong cardboard, and typically about 5 feet tall.

Step 1: Wrap your loudspeaker in the furniture wrap. Go around several times.
Step 2: Wrap your loudspeaker in at least a 2" layer of bubble wrap.
Step 3: Layer the bottom of your wardrobe carton with:
-> 1" layer bubble wrap
-> 1" layer packing popcorn
-> 1" layer bubble wrap

Put your wrapped loudspeaker in the carton and fill with packing popcorn. Fill above that with layers of packing popcorn and bubble wrap.

Assuming that your speaker is not 5 feet tall, using a box cutter, cut the top of the carton to fold over the loudspeaker and seal up.

If you've got a loudspeaker that is worth $4000 or more, than instead of getting only $500 for it like you eventually will, or worse, give it to your kid for his college dorm room, then it's well worth it to pack it up this way.

I have Sundown SAM 500D with blown power supply fets and its drivers. The smd drivers were toasted so couldn’t read markings. This amplifier only uses a total of two drivers for both banks of FETS. One driver per side, as oppose to many designs were Fets are driven by two drivers (PNP and a NPN). This design also have a diode across each emitter and base of each driver (so am assuming thats why only one driver per side).

Amplifier uses a 494. Would MMBT3906 be suitable replacement? What diode to use? Am just a little confused on why it only uses one driver per side as oppose to two. Any help appreciated.

Also this amplifier uses a total of four FETs on the switching, two per side. I am using 3205’s with 68ohm gate resistor (the 47ohm resistors I had in stock were a bit too big in package size, hence why I used 68ohm).

look carefully the 4 transistor is pointing to same direction
any diy schematic like this all around the world?

Hi all,

I have a possibly quick & probably basic question that I hope one of you may help with: It is how (deep) bass is reproduced with an OB loudspeaker? Would one normally use some kind of EQ (analog or digital filtering) or can a sufficient deep bass level be achieved with "normal means"?

If someone might have a link to an article (or the like) that describes achievable (deep) bass levels with an OB construction vs. maybe "baffle size" I'd appreciate such information.

Cheers & thanks for any insights on this 😉

Jesper

Folks,

I post class TD schematic. It is based on the only famous class TD.
This is not yet trial. Layout is not yet available. I bring new idea for gate supply, and more simple design suitable for DIY audio pro enthusiast, dreamer for big muscle amp.
Sorry small mistake, R126 is not 27K. but 18K

Regards,
Kartino

Hi!
I'd tried to pair the digital amplifier Sabaj A30A via the USB-C input with a Raspberry Pi Zero 2W loaded with Picoreplayer 8.3.0 as a streamer (digital source). I used Pi -> micro-USB OTG -> male USB-A to male USB-C -> Sabaj A30A. With OTG cable in the chain Sabaj could display 44.1 on the USB display (with a single cable micro-usb to usb-c it could not) But the Pi continue to be unable to see the Sabaj. (aplay -l show me no soundcard) I think it is maybe a setting output problem or a problem related with the micro-usb - usb-c chain. Any help?
Thank you!

(I'm going to keep this a standard schpeel, I hope the Mods don't mind. If so please let me know)

I'll be popping in fairly often I'm cleaning out and stumbling on things that are laying around that the community might need.

Certainly not looking to get rich here. Make me a reasonable offer on most of the stuff I unearth and I'll probably take it. Seems a shame to have it in a cardboard box somewhere if it can be used.

Please keep it in the US - I don't really have the time to do paperwork, and i don't want to take the time to research what something might be worth.

So make a reasonable offer - PM Me - remembering it's going to take a few dollars to get it to you.

All Gone. Happy building !

(I'm going to keep this a standard schpeel, I hope the Mods don't mind. If so please let me know)

I'll be popping in fairly often. I'm cleaning out and stumbling on things that the community might need.

Certainly not looking to get rich here. Make me a reasonable offer on most of the stuff I unearth and I'll probably take it. Seems a shame to have it in a cardboard box somewhere if it can be used.

Please keep it in the US - I don't really have the time to do paperwork, and i don't want to take the time to research what something might be worth.

So make a reasonable offer - PM Me - remembering it's going to take a few dollars to get it to you.



There are 11 Toshiba J74 BL and 7 K170 BL as in the pics. A few have been soldered and a couple trimmed. Purchased a zillion years ago from B&D so they are real. Not sure if these are still in demand. Make an offer on all of the Jfets. - Gone

More than 50X IRFP140 Power Mosfets and 4X IRFP9140 complimentary Power Mosfets. I used these exclusively for many Pass Amps. Higher currwent but lower voltage than the 240. Suitable fior most of the builds but sometimes you'd need less of them due to the increased current rating. The IRFP140 are very old NOS but have been on a 'matching rig'
Make an offer on all of the Power Mosfets

24X Samsung IRF9610 ideal for Alephs. It is my understanding these don't suffer the nonlinearity of the IR part. YMMV. Make an offer. - Gone

Good day, gentlemen thank you for your interest.
I still have a set of circuit boards for M2 to sell.
I have 27€ plus shipping.
Best regards abc4230

Good day, gentlemen

I still have a set of circuit boards for the Hepos tube preamplifier from diy.audio schop.de
to sell with some components. see pictures.
I imagined €80 plus shipping.
Greetings abc4230

Hi there, anyone have an extra universal power supply board I can buy? I'm building a firstwatt clone, I'm pretty sure they all use the same board from the diyaudio store, but they're out of stock for the next few months. Thanks!

Circuit board for building the 6L6 push-pull aTube amplifier from Electrosonique .
Offer a dormant project of a tube amp with building instructions. bought on ebay from Electrosonique. attached list of parts znd the 150uF Epcos are not on the list. the link to it.
https://electrosonique.eu/uncategorized/leiterplatten.
I would have imagined the price of 100 € plus shipping.
best regards anc4230

MiniDSP C-DSP 6x8 Used about one year.. $225 Plus Shipping.

I have just acquired an electrohome sr-2100 stereo receiver . the problem is that only one channel is working , I am trying to replace the output power transistors and I cannot find any information on them , this receiver uses the Motorola SJ5564 transistor .
does any one out-there know anything about these transistors !

is there a substitute for the sj5564 ? google searches on them comes up zero .

any help would be greatly appreciated , this is a beautiful receiver and I want it back in 100% working order .

Dear members,

First post but have enjoy reading since started doing own modding and learning(I hope!)

Coming from engineering background I make every attempt to keep it safe and stay within ability and after finding able to fix a few simple problem with spares/ repairs amps etc, caught the bug(as it were?!)
Confident with soldering now and interest is in marantz equipment and becoming more familiar with components and upgrading them with amazing results.

Would really appreciate some pictorial assistance with connecting a tube output ( kit form) with left and right channels, safely into the Philips tda 1541a?

I've seen one method but it's only ONE wire from the link wire directly below it and capacitor just below that to the right disconnected at upper end. I was thinking you would need left/right channel from tda to l/r channels to tube input?

im going for a smaller lower voltage kit and upgrading components where necessary. I already have a 12v version but have seen dual 18v version I believe dual rail regs and heatsinks which appears better in theory?
Further mods interested in and able to do ok myself are:

1/ improved op amps(burr brown?)

2/NOS mode

3/New capacitors inc audiograde film/oil at 1uf and below where appropriate.

4/Remove transformer of PCB and wire in separate toroidals for 5v and 15v plus power for tubes via toroidal. I may use soft start and individual fuse them.

5/upgrade regulators/heat shields because this made a big difference to my pm-32 project( expensive but worth it, I thought)

6/ shielded and twisted cabling neatly positioned( with earth drain where needed.

7/ mains filter

Damp the casing and was considering adding weight to the bottom exterior as well.

8/Better RCA, silver wiring made up by myself

9/damping the crystal(new?)
or possibly trichord upgrade?

10/ modding the puck as follows:
floating roller bearing system on a arm

c/s screw through puck into above allowing adjustment to tension/height

adding thick silicon oil to cavity in puck and seal off with washer in an attempt to act as a harmonic balancer and hope to aid in vibration? Worth a try.

ive also found on cdm-4 that if thin rubber on spindle is worn then it can cause disc to slip and come up with read error?

Not compitant enough to build separate supplies have had success in multiple toroidal build on separate case which switched on with main cd unit. Used aircraft style metal connectors. Having longer AC voltage cables and DC voltage PSU left in close proximity on PCB as factory but with better components still made quite a difference.




Many thanks, Phil

Cześć,
Próbuję sprawdzić Marantza CD73.
Do co mniej dziwnego. Podczas pracy nie świeci się 1 dioda LED z górnego związku. Czasami po przesłaniu płyty jest trochę zrzędliwy i brudny. Diody też potrafią wariować, np. migotać, ale to nie są zimne luty. Jeśli zaprogramuję utwory np. 3, 5,7 i dołączę badanie dźwięku i wszystko inne działa prawidłowo. Elektrolity są wymienione na wszystkich PCB. Z zasilacza wyprowadź prawidłowe napięcie. Trzymam się na ślepo MAB8420 więc mam na schemacie i właściwie jest na MAB8440P a na płycie CD MAB8440PB. Jakieś pomysły, czy któraś z Was już tak miała?

Mirosław

I have to wonder what the availability of endless entertainment has done to the Human race. By endless entertainment, I mean the infinite whole of on-line / computer driven available ways to occupy ones time; videos, games, social media. Having grown up during an era when these things simply did not exist, I can see the change in people of today. My baseline example is you used to be able to say "hello" to someone, but these days they're wholly occupied with some device. Used to be they'd be interested in talking with you, half the reason being they're bored; there's actually nothing else to do.

Now, let's conceptually add AGI into the mix. AGI being AI based general machine intelligence. So now you have available a literal conversational partner, whose intellect and knowledge easily surpasses 99.9% of all real persons you could talk to. Why would anyone bother to talk with a real person anymore? Whatever time is left over from the games, movies and posts, you can real time chat on into the night with an intelligence no Human could hope to equal. In contrast, an ordinary human being would seem "as dumb as a post".

My guess, when this comes on line in a matter of time, is that in the limit, interpersonal human interaction will become even more damaged than it is already. I only hope to God that this does not follow the trajectory of the internet, which was supposed to be this and instead became that. I sincerely hope the monetization at all and any cost does not prevail with AIG, for that will be the downfall of Mankind.

Imagine an AI that's trained to keep you engaged, then try its best intellectual approach to sell you something. And everyone of them is that way. The analogy of a Cee eN eN story page; text driveling on and on, page after page, never quite getting to the point of the article title, with all these flashing, moving adverts sprinkled about on the left, right and even in between the verbiage. Me? I closed that page, no longer caring to know. Good Luck, humanity.

What do you think?

I'll be putting in the order for the remaining components to complete phase 1 of my ADC audio test kit so I thought I'd start using this thread as my blog as I go through.

The overall concept is to have a USB connected ADC that operates stereo balanced at 192KHz 32bit. I'm using a AK5572 board from nilita that includes opamp front ends, biasing and some power supplies. However I need to add some bits:
a) a case - a hammond metal one should be a good RFI resisting starting point.
b) a clock source - for phase 1 I will use a channel of my sig gen with the board setup with 50Ohm termination, then phase 2 I'll look at options for an internal clock.
c) a STM32 based discovery board - this will operate as the PCM/i2s to USB bridge - I have to write some code as part of this blog to get this to work - naturally if I can get this to work it's available for everyone to use as they see fit.
d) a couple of power supplies - initially in phase 1 I will use my bench power supply (SMPS so noisy) but in phase two I'll switch to a small internal linear supply. The ADC board will need +15, -15 and +5V and a second +5V for the STM board.
e) AC coupling components - I'll use 10uF MKP4 caps. I'm not interested in DC for this system. The maximum of 4Vpp inline with XLR.
f) AC High voltage option - A simple 100Vpp or 400Vpp using a simple 9M+1M voltage divider ahead of the capacitors. Phase 1.5. This is for speaker or tube use and should give me 400Vpp.

The way the system will operate is that the ADC board will be configured as master with the MCLK connected to the sig gen at 24.576MHz (I may try higher if the Mac can cope). The ADC will then clock the PCM frame clock and bit clocks across into the STM discovery board where the STM will be configured as a slave.

Inside the STM, the system will be configured to detect the FIFO 1/2 full, causing an interrupt and that will then drive a DMA (no CPU used) to transfer the data from the FIFO into PSRAM ring buffer on the discovery board.

The STM will be configured to use OTG HS USB that's available on the discovery board. The USB OTG will declare itself as a USB Audio Class 2.0 (UAC2) device and the Mac will then see it as a USB Audio device like a microphone making it available to any app (Mac or Linux in a VM) such as REW etc. The important part here is the use of USB HighSpeed (480Mbit/sec) which the data rate requires and the use of UAC2 that supports the high data rate.

Internally the STM code will setup so that when a isochronous USB frame can be sent, the driver will DMA the data from the ring buffer in PSRAM directly into the USB output, in a diagram:

REW Application <-- MAC USB <------USB HighSpeed---- [STM USB] <--DMA-- Ring buffer <--DMA-- STM FIFO <- [GPIO PCM] <--- ADC

The first phase of this will be hard coded to 192KHz 32bit but as the ADC also offers control via i2c, I can also add soft control and then expose that control via the UAC2 control commands. This soft control will allow me to alter the rate and other configuration via REW etc. However a hard coded rate first will be enough.

This should all sit in a large steel case and as I progress I will keep an eye on noise etc but for now this should help keep noise down. If need be I'll address noise with additional shielding.

Testing the ADC board so far has been successful:

Hi ll I'm after some advice locating some parts for my amp. I have a Carlsbro Cobra 90 keyboard amp which is missing the fuse and holder that connects at the back of the amp. Does anyone know where I might locate these items from Thank you.

Hello.
I have too much units on the shelf and some of them has to go:

Audiotechnology 18H52/17/06/SD 4 Ohms SOLD!
Original boxes. Very good condition. 100 to 150 hours of carefully use only in HiFi. Connection terminals not soldered


T/S Parametar taken with DATS V3

D 130 [mm]
Re 4.126 [Ohms]
Fs 44.88 [Hz]
Zm 23.81 [Ohms]
BL 8.519 [N/A]
Qms 1.86
Qes 0.3897
Qts 0.3222
Vas 12.8 [liters]
L10k 0.05936 [mH]
n0 0.2831 [%]
Ms 24.31 [grams]
Cms 0.517 [mm/N]

I’m always playing, I’m currently thinking about getting some styrofoam eggs of various sizes, wrapping them in glass, body filler-ing to get a nice smooth surface and then using acetone to dissolve the foam. Are jet engine shaped enclosures really all that much better than a basic cubic enclosure with well rounded edges? I tend to build in the bookshelf size category.

Hello
I am looking at installing one of these into my amplifier to try and prevent my children and other youths damaging my speakers.
https://www.ebay.co.uk/itm/38483493...rentrq:0e11d7241870a77d3328108cfffff928|iid:1
Amp board: https://store.sure-electronics.com/product/256
Power supply: https://www.meanwell-web.com/en-gb/ac-dc-single-output-led-driver-mix-mode-cv-cc-with-hlg--240h--36a
The speakers are two way DIY 17cm bass reflex with silk dome tweeter. Would have to look up drivers.
Do they work?
Are they any good?
Will it degrade the sound quality?

3-way TQWT 10”/6”/1” - Seas ; Satori - need woofer advise!!

Hello everybody,

I am currently trying to design my first DIY speaker, a 3-way 10/12”- 6”- 1” and hesitate between 2 options, described below.
I would greatly appreciate if you have any advice on drivers to be used, as this is the biggest question mark for me before I pull the trigger.
I have a budget of ~800EUROS for the complete stereo driver set. (flexible)


So far, I plan to use:

• An LR2 cross-over: W – ~300hz – M – 2600Hz – T. Using quality components (to be fine-tuned).
• Two separate cabs for mid and woofer in 22mm Ply Wood/ MDF + bracing.
  • M: ~15L closed box.
  • W: ~65L Transmission Line. (offset ~0.3 ; 1:6 ratio)
• Stepped Mid baffle to have time alignment between Mid and Tweeter.

OPTION 1:

• Tweeter: SB29RDCN-C000-4 (also contemplating TW29RN-B-8 or SB26ADC-C000-4, even D3004/660000)

• Mid: Satori MR16P-8

• Woofer: Seas CA26RFX H1305-08
  OR, ordered by preference:

Pros:

• 8ohms nominal amplifier-friendly impedance
• Woofer’s Qts of 0.34 is a good fit for transmission line.

Cons:

• CA26RFX woofer will be the weakest element of the chain. A shame since I really plan to fine-tune the transmission line.
• SB29RDCN tweeter might have a bit high Harmonic Distortion for my taste, but I never tried it.

_________________________________________________________

OPTION 2: use of High efficiency woofer:

• Tweeter:SB29RDCN-C000-4 (also contemplating TW29RN-B-8)
• - Mid: Satori MR16P-4
• - Woofer: Dayton 12” PA310-8
  OR..?

Pros:

• Great sensitivity, 92-93dB average
• Pro woofer brings fast, articulated BASS

Cons:

• Woofer might not go low enough
• Difficulty to match Mid and Woofer sensitivity.

OPTION 3 would be to go active on the woofer, allowing me to correct room response, but I do not plan this yet (messy setup, potential quality loss in RCA cables, extra cost)



I have access to an acoustic lab with Microphone, DATS v2, Keyence Laser for membrane measurement, Klippel, and even a vibrometer to fine-tune the box if needed. (Lucky me 🙂)


I plan to keep the speakers in the lab, and fine-tune them until I optimized all variables that could impact the performances. (I plan to move from apartment to home within a year, so not fine-tune for the room)
By the way, if somebody is interested in reusing my optimized design later on, I could share everything I have. Even better: if somebody would like us to do this build together, we could order all components twice and have better pairing of the drivers/cross over components.
I had a look at many DIY sites, especially Troels, and the Jenzen CA was first on my list for a while.

A HAPPY NEW YEAR GUYS,

I started a new FreeDSP project named "FreeDSP Catamaran A/B"
"Catamaran" comes from Stacked Dual-mono construction boards. It intends to use a 96kHz sampling 4-way stereo crossover dividing network application.
"A/B" means dual boot EEPROM feature as same as my previous FreeDSP products.
That construction improves cross-talk performance and increases the number of programming steps.
A highlight of this board design is a high-performance differential mode ADAU1701 embedded ADC circuit.
It reduces remain noise by 3dB and a large signal (-20dB to 0dB) distortion drastically.

According to my experiment on FreeDSP Classic SMD A/B overall(ADC --> DAC) THD performance indicates as follows...
Frequency | Single-End | Differential
100Hz | 0.00723% --> 0.00287%
1kHz | 0.00642% --> 0.00171%

It will satisfy most cases of audio users' channel divider applications.

CyberPit

Someone has asked me to look at a pair of Wharfedales that play ok for a while then cut out. Once the amp has been turned off and on again they seem to start playing again but will cut out again later on. Have tried them with several amps ( some without protection circuits) and it is the same on all of them. I notice that the specs on the back of the amp show the tweeter size and in brackets it says "Protected". Does this mean that there is a protection circuit in the crossover which is triggering the cut-out, and if so, is there an easy remedy for this. I am not playing at excessive volumes etc. Thanks.

I have noticed...

the tabs coloring has become non contrasting and they want you to download skins...and what not
After every few days, the software has to be updated
and only update you see is the ads and useless features
Hope you get what I mean

gajanan phadte

hello everyone!) does anyone have a martin king matlab model for transmission lines?

Hello. This is my first post. I have been perusing the DIY forums for a few years now. A couple years ago I had completed a build of four of Art Welter's Keystone subs and it's been a steep learning curve, but I'm gettin' there.

I'm working my way into building tops now and I've always been fascinated by Multiple Entry Horns (MEH, Unity horns, Synergy horns, etc). I've been considering building a sort of hybrid MEH/Line Source. The concept is four stacked B&C DCX464 mid/high coax drivers with the new 90 degree waveguide extension WG148-90.10 in their Suggested Designs section to cover 500Hz and above, and then 8 10" drivers to cover the lows and low mids. This design would have a 90 degree exponential horn extending beyond the waveguide extension with 1/4 wavelength ports like an MEH design would have. Right now I'm looking at B&C's 10NW76 as a possible 10" driver choice.

The photo's going to immediately look like a Danley J7 but that's not intentional and I've seen the J7's insides and it's not even close to the same. It's just sort of how this turned out. The waveguides end up stacking to around 39 inches top-to-bottom for the center. Adding the 10" drivers in an MEH-style just sort of ended up this way.

From a design standpoint, I'm trying to create a loud and high-fidelity speaker with good pattern control for live sound applications and a simple 2-way low/high design from a powering perspective (since technically the DCX-464 is already a 2-way driver).

Things I don't know:
1) can I stack line array waveguides like this without too much destructive interference? The person 3-D printing them for me will be modifying the WG148-90 to have zero verticality for the center two HF drivers and then a +20 degrees for the top and +20 degrees for the bottom. My thought is that I would like to gain that acoustic summation similar to a line source, but for all I know there's a reason I haven't seen this design on the forums and that's cuz it just doesn't work with physics.
2) would there be any benefit to mounting the 10" drivers to the horn if I expect the DCX to get down to 500Hz? I can always lengthen the horn and I assume that the horn length needs to be 1/4 wavelength long of the lowest frequency that I want directivity for. This is around 1.42 feet for each side of the horizontal horn right now, which should get me down to 198.7Hz if that's how that works. Again - new to this on the math side of things.
3) do the lows need to be in their own chamber to protect the DCX drivers from internal box pressure? My gut says yes and I've seen other designs that do that. I am guessing that I would need an enclosure that meets the driver's Vas ratings plus a little more.
4) I just don't know what I don't know.

Thanks!
Steve

First, as PSA: you may find it written that there is no need to upgrade the cheapo switching power supply that ships with the Chord 2Qute.
This is a lie. Upgrading to a low noise, regulated linear power supply makes all the difference in the world.
The 12V 4A Brzhifi power supply I use is shown in the background of this photo:


While I haven't opened up the case to check, the Brzhifi power supply internals are supposed to look like this:

It's a standard extruded aluminum project box, serviceable toroidal transformer, 2x 12 VDC outputs (not independent, just two taps connected to the regulated output), power switch, and indicator light. Reassuringly the output measured 12.1 V on power up and remained 12.1 V after warm-up, unloaded, no funny business whatsoever. Whether it can meet its specified 4 A output without flaming out is an open question, but let's face it I'm not going to be putting that to the test.

The 2Qute DAC itself is at once understated and outlandish. The milled aluminum pillbox case is extremely solid and carefully finished with deeply engraved lettering on the top. At 400g, the case is heavy enough that it doesn't usually lose the fight with stiff cables. The magnifying "eye" window is centered above a single indicator LED that changes color with the sampling rate or the selected input. Speaking of inputs, there is one each coax (RCA), Toslink, and USB, switchable with a tiny button on the rear. It's easy perhaps to mock that cyclops window, but it absolutely works from an aesthetic standpoint.

Inside, it's just a small circuit board, powered by 12V DC delivered through a sleeve-type 5.5x2.1 mm power jack. What distinguishes these Chord DACs from just about all the other DACs on the market is the use of an FPGA (Field Programmable Gate Array) chip instead of an off-the-shelf, purpose-built DACs from AKM, Wolfson, ESS &c. An FPGA is microchip with user-configurable logic. It isn't a DAC, but with enough programming effort, it can be turned into one. While expensive, in the context of high-end audio the parts costs are manageable [The XC6SLX9 Chord uses in the 2Qute is currently less than $50 at digikey, but it might have been more in 2014 when the DAC was introduced.] I'm not sure what it is Chord needs this chip to do that can't be accomplished by a dedicated DAC chip - something about lots of filter taps - but I can't argue with the results.

I wan,t to buy, both if available, or just one. Pls call. eight o four too too one too three three one.
Thanks, Tom

Hey all!

I have a Yamaha DG-1000 preamp which I am very happy with. There's really only one small problem with it, and that is that the input signal on my passive guitars doesn't get loud enough to bring it up the ideal level - just below where you are triggering the red clipping led. Now, I actually had a chance to play a Yamaha DG-100 combo amp (it contains basically the same preamp) recently, and the HIGH input channel on it seemed to be much better for my guitar, as it provided enough gain to clip the input. Of course, I obviously turn down the input trim pot afterwards as the manual instructs.

The Yamaha DG-1000 offers only one input, and, looking at the schematics, seems to basically be the LOW input section of a DG-80/DG-100 with some capacitors and resistors changed to be that of the HIGH channel. The differences between the HIGH and LOW inputs are rather stark if you look at the schematics. Although they are somewhat confusing to a relatively inexperienced hobbyist such as myself, I think the LOW input goes through an additional opamp, which simply isn't present on the DG-1000.

My question is as such - can I make the input of the preamp hotter by doing something as simple as changing the trim potentiometer from 50K to something else? Or even the resistor after it in series? I think it's a higher value I'm looking for, as long as the I'm interpreting the diagram correctly. (I very easily could be mistaken here) Another question follows - SHOULD I even do this? The input circuitry on this seems rather complex I don't just want to go fiddling around with it just because I think I have a good idea and then just ending up making it worse because of some unforeseen effect it will have on the circuit. If this is a terrible idea - no worries, there really is nothing fundamentally wrong with the tone/performance of the preamp as it is. I'd just hate to be missing out on some small benefit because of something as seemingly trivial as input gain.

Thanks in advance!

Quick forum search had me in disbelief this hadn't made the rounds here:

Thought I’d ask here, I’m working on a Kyrocera A-910 which is a fairly high end integrated amplifier rated at 150 watts per channel. It has many nice parts in it. On each driver board there is a 4.7 uF bipolar cap in position C523



They used a very large in physical size crossover capacitor. Which is weird as they had other non polar Elna caps of other values in the amp that were much smaller in physical size. So I’m curious why they would choose this cap for this position. The reason I say speaker crossover part is because I’ve pulled many of this exact cap from cheaper crossover when rebuilding speakers.




Initially I was just going to use a Nichicon ES Muse or Nichicons other bipolar series, but I thought I should figure out why a speaker crossover type? Would I be better off with a 4.7 uF polypropylene?

Any help on figuring out why would be greatly appreciated. Would a Nichicon ES be okay here or should I find something that would be used in a speaker crossover? Only issue is the poly would be big. Guess I could add an electrolytic to my next order.

Dan

I have an old kenwood receiver that I've always used for a PC sound system. I believe it's an 80s model, purchased late 90s, been going ever since. But the hum is driving me nuts. Do amps increase in hum over time? Is it worth working on it? How do I decrease the hum? Is it 60 cycle? Couple of caps maybe? Or should I just go for andecent integrated amp. I have a Rotel from the 90s that hardly hums at all.

Purchased this Hafler 945 series preamp recently. Determined it's locked in Mute mode which is only accessible through the remote control system; and I don't have the factory remote. Programmed my Harmony 300 with the Hafler codes, but that doesn't trigger the Mute circuit. Heard from someone with a Hafler Iris that he was able to remove the remote pcb which made the preamp controllable through the knobs, without remote control of course, which would be fine for me.

The user manual, which is a little more extensive than most, is easily available; but cannot locate a service manual or schematics anywhere. Inspecting the unit I notice that the two large power circuit electrolytics have leaked, but doubt those would cause the Mute situation. The pcb containing the remote control "eye" is fairly extensive and contains lots of stuff other than the remote receiver.

Anyway, best thing would be to get the schematics so I could see what it's all about; I just don't have the skill or experience to tackle this thing without documentation. Checked all the usual sources including fee-services, but no luck. If anyone has a service manual, or knows of a source, or would be willing to send copies of key pages, or has any other ideas, I would be eternally grateful.

Thanks,
Warren

Up for sale 2x FA253, boxed from day1, no dust etc
Excellent condition, just need to rearrange hifi stuff due to newborn 🙂
900E

Hey folks,

I need some guidance here.
I have some experience on class a/b amps, have troubleshooted and restored a lot of pioneers, marantz, realistic, etc... but this is my first Carver.
This is not a magnetic field unit. Not the TFM 35x either (a lot of similarities though).

I have replaced all electrolytic caps, and a few faulty components: one of the ICs in the input board that was intermintently shorting, blown fusible resistors and bad diodes.
I have also replaced all transistors in the amp circuit.
Everything seems fine and stable but there is a DC voltage in the right channel that I am not able to get rid of. It is 0.8V and it won't budge no matter what.

I tried replacing back old output transistors and pre drivers one by one and did not make any difference.
I HFE matched the predrivers and also no change.
There is no bias offset adjustment on this amp, just IDLE current adjustment trim pots, but the TP testing points are not showing anything usable.

I need a peer to review and help me to troubleshoot this issue.
I am not comfortable with this DC voltage coming out of the amp.
DMM, o-scope, thermal camera, audio SG are available...

When I opened it to do the repair, I found a bulged 220uF/25v electrolytic capacitor in the power supply. Replace capacitor. The device still doesn't work. Taking a closer look at the amplified audio output, I found the integrated audio output completely burned out (I can't identify the code). Just know it's smd and 28 pin. It must be from the TPA3118 Class D line.

Hello guys, i recently bought second hand black widow 1801 peavey subwoofer, is the old one with the spider logo on it.

i searched online for any plans but i cant find something

I am planning to buy me an exercise bike.
Now I want to know if you have any experience of such a maskin?

I must give my body some movement.
Or I may die soon. At least sooner 😀

It seems that GRS has released a new product line of ribbon tweeters, in collaboration with Fountek. Interesting. Here's some info from the link below:

GRS's premium high-end ribbon tweeters take everything you love about Fountek's Neo series and updated it with the latest in materials and motor technology! Easily reach frequencies of 40kHz for incredible detail from your hi-fi system!

https://www.parts-express.com/GRS-RT1.0-8-Hi-Res-Neo-Ribbon-Tweeter-8-Ohm-272-200

Anyone tried them out? I wonder what differences they have from the original Fountek Neo series?

Hello, new to this side of the forum, mostly hang out on the tube side 🙂

I'm planning on integrating a USB DAC into another project, I looked around and found a lot of stuff about the PCM27xx chips but they are long since discontinued and seem a bit hard to get so I was thinking of using the PCM2900c for my project.

My question is whether I should use the analog output of this chip directly or if you think I'd be much better off using it as a USB to I2S interface to feed to another DAC chip(if so, which chip?). Output power is somewhat unimportant as there will be an amp stage after this 🙂

The main reason I'm asking is because the PCM2900 "only" has a 16-bit DAC and 48KHz sample rate max, 16-bit seems pretty alright but 48KHz seems a bit low for a high quality DAC(most projects I've seen are well over double this speed)?

Hi friends,
I was build this amp: www.jogis-roehrenbude.de/Verstaerker/GU50-Grommes/GU50.htm

It is slightly modified this EL34 amp: www.jogis-roehrenbude.de/Leserbriefe/Roessler-Amp/Bauanleitung.htm

My question: Please, what anode current I can use in this GU50 amp ? 😕 I use about 460V DC in anode and -70 in bias input ..

PS: I use on tubes AC heater with this reference because with AC heater was hum in sound ...



Sorry for my bad english 🙂

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Seems that the industry body has decided that it's time to do away with 1x/10x switchable probes!

I have to say I've mostly used 10x and with the clocking stuff that's on 1x with SMB/BNC connections anyway.

Hey all,

I have been playing with my Current Drive modified LM3886 based amp...so far for home Audio, well, didn't really perceive a "positive influence" on my Quad ESLs (sounds different, yes, but better?)

But for my homemade LM3886 based Guitar amp, I absolutely love it with my Roland JC120 JFET based DIY preamp.

Now I was just fixing a friends Fender Stage Lead and was looking at the schematic (attached)...I notice (in red circle) the neg/Grnd speaker lead is grounded with a .22ohm resistor and is actually part of the Feedback circuit... is this amp running in Current Drive?

Good day forum
Can someone help me with the correct placement of my wiring from transformer to rectifier to PCB please

In progress: 3-way line array consisting of:
12 e,a, Satori 5" MW13TX-8 in cardioide, power tapered in 3 steps
Satori TW29BNWG tweeter
6 e.a Wavecor SW182BD03 7"rear subwoofers in closed box /EQ
Hypex 503 integrated at bottom rear in column.
Dummy-box is tested and revised a couple of times..
Will it sink or will it flow ;-)

​

A friend of mine accidently connected a solid-state power amp(switched on) and a pair of tube power amp(switched off) to the same speaker through speaker cables. As soon as the solid-state amp was switched on there was some sharp noice from the tweeters and the amp was immediately switched off but the damage was done. There was smoke from the tweeters and smoke, and later inspection and testing showed that the tweeters were burnt and a diaphragm of one mid compression driver was damaged, and the speaker crossovers(resistors, caps and inductors) went bad as well. There was damage in the non-playing tube power amps as well. And when the solid-state power amp was checked later, there were no issues found it it.
Now, the question is: how did so much damage happen, what could have caused it, especially when the tube amp was switched off. Somebody suggested that since the tube amps were switched off, it would have no effect whatsoever.

Can someone with technical know-how throw some light on the cause of the incident, was it some kind of interaction between the amplifiers or some grounding issues or oscillation in the solid-state power amp?

I’m trying to start a build based on some of the more generic 300B designs (JE, JC Morrison, etc…) and I’ve run into my first major issue that’s had me stumped for a few days now.

I have a 400-0-400 -> 5U4GB -> CLCRC supply with a “slow, meandering” noise voltage at the input of C2 which makes its way all the way down. (about as far upstream as I want to stick my scope probe) Any idea what could cause this?

(for reference, carrier wave is the 120hz, vert scale 100mv)



I’ve tried different tubes, i’ve tried rearranging the LCR elements but i’m always getting it. The only constant has been the fact that the supply has always been tested with the “main load” being the two 300B power stages, albeit without the input stage, just the -70v on the grids via resistor to ground. (My thought is that i’ll commit to the input stage later since i’ve heard this is the biggest challenge with these amps. )

I haven’t been able to measure this voltage unloaded without the power tubes/opt… i know i’m leaving a lot of variables in the circuit but i’m not sure what to use as a dummy load for B+, I read some bad advice on this forum to use lightbulbs in series and ended up arcing over a perfectly good rectifier 😭 hard lesson that bulbs are like shorts when cold … i’m thinking of maybe cascoding a 6336 tube as a special supply testing unit

I am always looking for cheap amps in the local classified ads, but this one is not quite cheap enough. The reason I am posting is that the circuit is not typical. It would be interesting to give it a listen if the layout and construction wasn't so poor and the main capacitors so small. (I would replace the electrolytic coupling caps and inject the signal directly to the power amp of course.)

It has an additional LTP after the input. BUT, I wouldn't call it a dual-differential; because this one also has your typical single ended VAS like 90% of amps. One additional stage, therefore. It must have high loop gain at 100Hz and 10Hz, and according to Putzeys this is the way to go (regarless of loop gain at higher frequencies; it can be good, but it's not as important as the low frequency feedback).

As per title, please send pm if you have one and are willing to sell

So after pulling what little hair I have left. Due to the lack of TS for any speaker made in my country. I deicded to bite the bullet and just buy a Dats V3.
This is my first speaker build and this is the spec for the 10 Inch woofer I plan to use.
I plan to add a tweeter and a Midrange will add those scans also in a bit.
Im sorry I dont have a calibrated Mic as of yet but am working on getting one.
Questions
1. What freq would you cross this driver.
2. Do you think this will give me good bass. Or will I need to buy a Sub also. Was kinda hoping this would do a decent job on the bass. Given a large enough box. In WinISD it recomends a pretty large box 85+ Ltrs.
This is a cheap budget woofer. So Im not expecting special. But it does sound pretty decent when I hooked it up direct to my amp.
Once my box building confidence grows can think of costlier and better drivers.

This Kenwood Super Eleven came to me with shorted outputs in one channel, along with a few toasted drivers. I replaced the original 2SD555 and 2SB600 with MJ21194 and MJ21193 (both channels) and the other failed transistors with the same part numbers as originally installed. The issue I'm dealing with now is that I'm running out of available bias trimmer range in the original bad channel to reach the recommended 25V--I'm hitting 15mV max, versus 25mV in the other channel with room to spare.

No voltage readings I've taken comparing channels show anything unusual. I've also double-checked the following:

D10, an STV-4H
R44 (new)
VR4 (new)
Q10, Q12, and Q14

Could use another set (or several sets) of eyes on this.

Hello all, I have a Karik that appears almost unused, having been stored since purchase by a collector who recently passed away. Anyway, I opened the unit before testing it, and it looked really clean, no obviously damaged or leaking components, so I plugged it in and got the ”green light blinks a few times and then gives dark”. It didn’t occur to me to open the round-ish PS case. After researching, I found a lot of info that many of you had posted, and it was helpful, to a degree. I did pull the small caps, and they all literally lifted right off their posts and leaked some liquid. the two large caps test fine for 330uF and ESR. Put it back together and still got blinking light for a moment then darkness. I tested all the obvious diodes and resistors, they seem fine., as do Q1-Q3. There is this yellow thing that I gather is some kind of compound capacitor, it says “0.15uF X2 and 2x4700pF Y”. That thing looks like there was an explosion inside it. It’s cracked in multiple places. I was going to order a replacement, which is maybe $15 total, but I don’t know how to tell of this could be the problem, or if I’ll need to order other parts as well. Can anyone tell me what role this thing plays?

Heres another discrete OPAMP



Lets remove the offensive Q6 and replace it with a jumper. Probably this transistor is the bane of IC chips

Hi,
It looks like I have blown the optocouplers on a DADA electronic speaker protection unit. I can.t find the exact part or even a datasheet for it.
Can someone tell me an equivalent? Preferably from Mouser. I have found this but not sure if its the same https://au.mouser.com/ProductDetail/782-CNY17-3
Thanks,
Kffern

Here's a sim I made of Bose's new tapped horns

documentation is here: https://audioxpress.com/article/patent-review-bose-transmission-line-loudspeaker



US patent is here: https://patents.google.com/patent/US20150071473A1

I built my 2nd SSE maybe 5 or 6 years ago. Been working fine with no issues until about 2 months ago, when it started randomly blowing the fuse every few weeks or so, playing fine in between. Then about a week ago I started hearing static, almost like a grounding issue, in the right channel. Checking the input connection and replacing tubes didn’t fix the issue. I then remembered on my 1st SSE a wire on a board connector to the PC loosened up causing a problem with one channel, so I took a look to see if that was the issue on this one. What I found was in the right channel R17 (560-ohm 5W) was fried and C15 (1500uf 50V cap) didn’t look very good either. I’m surprised the channel was working at all. The same components on the left channel look fine. I have the parts to replace them, but I’m wondering if I should chalk it up to part failure, or should I be looking at what else may have caused those parts to fry? The U10 CCS screw that holds it to the board was bright silver when new but looks dull now. Maybe from heating up? The U20 CCS screw looks like new, bright. Could the CCS have caused the problem? Should I replace the U10 CCS also? I do have some extra IXCP10M45S on hand. Picked a few when Digi Key still had them awhile back. What other part(s) could have caused R17 and C12 to fry? Since it was playing well up until I looked underneath, (I even had it cranked up last Friday night and it sounded good, without static!), so I suppose I could replace the parts and then take some voltage readings to see if anything looks odd and figure that out then. Any help or thoughts would be appreciated, thanks, Mike.

Hi all,

I see the Yorkville SA-102 is has just 1x10-inches LF Woofer, 1xHF Compression Driver.

I am interested in a Synergy horn of this type, that uses 2 transducers.
How are the drivers loaded in this type of synergy?
What are the characteristics of this type of synergy?
What are the merits and downfalls?

Please point me to a DIY synergy post of this type,

Thank you,

I have observed that the OS is creating keyboard malware on Laptop as well as on mobile.

Toscanini is an evolution of Kubelik DAC (no longer available) but with a couple of tweaks. The main improvement is that although its still using six TDA1387 DAC chips, each is being 'overclocked' by about 50% to gain a higher SNR, noise being the primary artifact I work at reducing in my designs. In effect, six overclocked chips are doing the work of nine normal ones. Also Kubelik's power supply was a bit non-standard 20V, Toscanini lowers that to 15V so it'll be easier to find an off-the-shelf supply. The PCB offers a choice of the manufacturer of the filter inductors - Coilcraft SMD, Bourns SMD or through-hole - using the SMD ones makes for a lower profile PCB - better suited to vertical stacking for creating a multichannel DAC. Opamps can be rolled to taste, for the stock design I'm going for ADA4075-2 of which Mouser had plenty in stock when I last checked.

Schematic now uploaded, BOM & Gerbers too.

There are 3 inductor choices on the Mouser BOM, only two of which are available from Mouser. Coilcrafts like in the photo below don't seem to be available from Mouser but can be gotten direct from Coilcraft I believe. Note that I built the proto with 8.2mH as I couldn't obtain any 6.8mH - Coilcraft now only send out samples to registered companies here in China and Chinese copies have poor (20%) tolerance. The higher value needs to be paired with a higher I/V resistor and thus leads to a higher max output voltage.

The total cost of all the Mouser parts is about 32USD to which you'll need to add the cost of the TDA1387s (from Aliexpress or eBay) and the PCB (presumably from JLCPCB).

Wondering if anyone has a schematic of the power supply for this amp.

It's in protect, and the documentation I found for the amp, has a basic block diagram for the PS (494 based).

I know I have a slim chance...

Hey people,

short question, I need a tl071, but I just have tl072. Will it work, if I connect it according to the schematic, and put the unused second positive/ negative in & the second out together on ground via a 100n cap?

I picked up an old Sony CD player, a CDP-591. Surprisingly good sound for what looks like a fairly old and simple machine. I don't think I have ever had a player that reads the disc so quickly.
It is however ridiculously sensitive to any knocks or bumps. If I place a mug of tea on the same table it is sitting on then it skips. If I place a remote control on the top of it, it skips.
Is this normal for this model, or has something become worn with age. Is it curable?
Cheers

Hey guys I'm fairly new here and I don't post much at all but love reading the various topics on the forum. I have in my possession these beefy Jeff Rowland knockoff heat sinks and I was curious if these would be of adequate size to cool a First Watt F4 or F6 at an average bias level? I'm really interested in another amp project and would love to build one or both of these at some point in the near future.

These heat sinks measure 13" Long X 5-1/4" Tall X 2-5/8" Deep. I know that I would need to sort out transistor mounting but that isn't an issue for me at all.

Thanks in advance for your time and advise guys!

Still cleaning stuff out. I have no plans to use these heatsinks.

There are a four types

1)approx 6.5" X 2.75" X 3" - there are 12 of these. 6 have a 4 threaded holes on the back for mounting. 6 have a slot up each side where a bolt can slide in for mounting.
To give an idea of what they can dissipate - I used 1 per output FET for a firstwatt M2 and the amp ran fine.

2)approx 15" X 7" X 1.75" - there are 2 of these - Fins are beveled on one side - no idea what they will dissipate

3)approx 9" X 7" X 1.75" - there are 2 of these - similar to #2 but shorter and without bevels - no idea what they will dissipate

4)approx 15" X 7.5" X 1.5" - there are two of these - interesting profile with a flat 'ear' the full length. Not sure what you could do with them but maybe something interesting. Color is 'purpled'

If your interested in any of these send me a PM maybe we can figure something out. The 15" ones won't go USPS flat rate but the others can be worked into flat rate. There's always face to face as well. I despise Paypal and the new 'rules' unless we're talking friends n' family.