Two MF1 Power amplifier boards, new, assembled and tested, on heatsinks. As on original MF1 schematics, good material, Toshiba 1941/5198 output transistors. 20W/8 Ohms, adjustable to A-Class. Have assembled a few amps with such modules and IMHO they sound very nice.

Dimension of one modul 125x100x80mm.

Price 60€ for pair + shipping.

Regards

Hello.

Does anyone know if any of the F amps are either true balanced differential or can be turned into one ?
Kinda like what the AMB Labs beta24 power amplifier is.

Asking for a friend ... 😀

Guys, I was damping and putting bypass caps on my CD6000 and must have jammed the power switch that connects to the long plastic arm that turns on the unit.
If I hold the power button on the front of the unit all the way in, it comes on, if I release the pressure at all it turns off.
Can the switch in the box be repaired? If so how?
If I need to replace it does anyone know the part number and where I might find one?
See below for the switch box.
Thanks, Nut

I have a McIntosh MX113 that has been sitting on my shelf for several years. It was not working when I bought it. The seller indicated that it had a PSU problem. Indeed it did. The main transistor was blown and several resisters were either burned or burned completely through (open). Attached is the schematic. I have replaced all the resistors that were burned or destroyed (R209, burned thru; R208, burned and changed value; R222, burned thru). I replaced the original transistor Q202 (originally 2N3738) with a TIP50. The zener, D207 was broken so I replaced it with a 1N5946B (originally 1N982B).

I have disconnected all loads, including the center channel driver (right side of the schematic). I'm getting the following voltages at Q202:

C - 182 (should be 96)
B - 72 (should be 76)
E - 56 (should be 75)

This uses 2 segmented can capacitors and I have not replaced those (yet).

This is obviously a simple PSU but it has me baffled. I'd appreciate any suggestions about what to look at.

Thanks.

Hi,

I need a PMD100 or PMD200 chip.

Can anyone help??

Thanks.
Andy

Hi guys,
I have a MF M1DAC and there used to be slight intermittent crackle in right channel.. turning the DAC on off usually fixed it.. a few days back there was some more crackle and then no sound from the right channel. If I remove the left channel interconnect, I notice the right channel is VERY faint..

Any hope of fixing it?

I will resize and upload some pics..

I have just been informed by a USA legal website that AirPod Max users are complaining condensation & water build up .


Apple has offered repairs ranging from $29 to $59.


After an hour or so of use build up occurs --many complaints from US customers .


They cost (approx ) $550 , attorneys are at present investigating and gathering evidence and USA customers with the same problem can join a group legal claim ( if proved ) .


Sorry this applies only to the USA customers .

Hello
I’m fairly new with tube amplifiers (built a few simple ones before)


I’ve just started assembling a TSEII and stupidly made some assumptions about the transformers I have available to me, I did have a search around the forums before I ordered everything(I already had the transformers) but you know how it is, you find the tricky posts beyond your ken after you have started to build it (I guess better than when you turn it on for the first time…..)


My power transformer has no CT and I was planning on doing a hybrid graetz bridge to get a ground to the star point on the board and the voltage required, it seems to sim fine in PSUD2


However, I’ve come across some posts from Tubelab warning against using protection diodes on the rectifier legs because it blocks the neg voltage supply.
The Diodes in a hybrid bridge are not configured the same way but I thought I’d better ask in case it still blocks the neg voltage supply, and if it is a problem? has anyone got a solution that preferably doesn’t involve a new power transformer? (Pretty hard to access down here at the best of times….)


Thanks (I’m sure I will have more stupid questions in the near future)
Vernon

I picked up a couple of KP926 50w SITs. I was hoping to use these in a very small single ended amp like the Pass ACA with about 15 drain to source and 1.2A . This device is normaly on usualy has a - voltage at the gate but looking at the curves it looks like for my purpouse at 15v drain to source I may need a positive voltage on the gate. Anything wrong in doing this and any idea what the input resistance and capacidence might be when operated like this?

I've got Volume 1 of the AES loudspeaker article anthology which consists of Volume 1 (1953) through Volume 25 (1977). I also have Volume 2 of the AES loudspeaker article anthology which consists of Volume 26 (1978) through Volume 31 (1983). Both books are about 450 pages. Available from AES at $40 each. I'll sell them for $25 each with shipping free.

Hi All,
I have finally begun building an F5 amplifier that I bought the boards for about 10 years ago. Life happened and the build just had to be shelved. I have a couple of questions that I need help with. I am slightly above novice range when it comes to electronics, so please be patient with me. My Previous build experience includes a pair of ACAs and a Bottlehead Quickie.

1) I am also a woodworker. I realize that there are parts of this amp that will get hot. If I have appropriate heat sinking, and the base plat of the chassis is steel, would it be safe to build the rest of the enclosure out of hardwood?

2) I know it may be in the build guide, but how do I compute the amount of heat sinking necessary to keep this amp cool enough?

3) I forget what else I was going to ask.

Quite rare and hardcore DIY.
A guy have made himself a DIY vynil cutting lathe in Vilnius.
Thought this would be of interest to some members:


Tech Story: Making Records With DIY Cutting Lathe (Self-Built Dubplate Machine & Studio In Vilnius) - YouTube

Hi
I am searching for a toroidal transformer with 230 V in and sec. 2 X 7 volts 1000mA each and 2 X 18 Volts 1000 mA each, height max 40 mm.
small variations no problem, tried AWDIY but did not get response (yet).
Cheers, Tojoko.

Dear community

I'm up to modify my CD6000OSE. I already changed most Electrolytics, some rectifiers and added some damping to the chassis.
All this made it a better player, but it is still far away from what I'd like to get - and I think that would be possible to get out of the basic concept.

I read a lot of threads here about modifying this player. Unfortunately I did not find a thread about a tubed outputstage. But this is exactly what I'd like to implement.

I know that there was a player sold under the label HEART. They added a transformer (??? for filtering AND converting balanced to SE???) and two 6922 tubes.
This player was reviewed very well. I don't know the circuit they used and I don't know how they implemented their circuit. What I found was a link to "Thermionic Valvestages" by Thorsten Loesch. He describes different DAC principles and how to implement which circuit. Well, thats it, I thought.

My main issue now is, that my player - unlike the easier tunable CD63/67 - has two DACs(SM5872BS) instead of one. Each of them is fed by the same integrated circuit, that modifies the I2S signal for each DAC (L/R flag and DATA content). Each DAC has four analogue outputs - normally: L+L-R+R- (two balanced channels) - here in this case one DAC has got 1L+, 2L+, 1L-, 2L-, the other has 1R+, 2R+, 1R-, 2R-. Now Marantz uses two differential buffers to get again two single balaced signals (L+L-R+R-). One more buffer (HDAM) module per side convert this signal into SE signals. So far so complicated. I hope this is understandable and right. Here the sheme:

So in my eyes I have a few options:

++ use just one of the positive outputs, i.e. 1L+ and 1R+ right off the DACs and add Thorstens tube stage.
++ use one balanced pair of each dac, add a transformer to make it SE and a tube stage
++ use the first part of the players HDAMs to summarize all the doubled channels and add a tube stage
++ build four differential tube stages followed by 2 balanced2 SE tube stage (6 double triodes)

++ deeply modify this player, deactivate one DAC, deactivate the separating IC (TC160G11AU) and feed the other DAC with an external clock and the I2S stream right out of the TDA 1302T (drive logic). As an analogue stage I'd use a tube like Thorstens one.

My questions now are:

?? Is my analysis of the circuit right?
?? Which of the options might be the best?
?? Which would be the best simple one?

Thanks for reading. Please post just positive answers! I'm not skilled, I just read a lot and have a huge amount of dangerous quarter knowledge. I might be wrong and hope to get some help here.

Cheers Ernst

cash only 400$ pick in person

Please don't request unless you are going to buy same day as request to avoid overlapping offers IM UP TILL MIDNIGHT most nights

l Will provide sound demo if you want to show amp function if you have set of speakers that match listed rms, ohms & wattage bring them please wear mask contact me for my address ask for adam

if you need a pair of 10ft xlr cables i have some spare ill give for free if you want them

This amp is badass I've owned for 3 years an still going strong my reason for sale is my new diy subs need more

power so time for a upgrade

This still goes for 400$plus before shipping&tax used so 400$ is fair and final no low balls here's the specs


Tech Specs
Number of Channels: 2
Power Class: Class D
Watts/Side @ 8 ohms: 300W
Watts/Side @ 4 ohms: 525W
Watts/Side @ 2 ohms: 775W
Watts Bridged: 1550W @ 4 ohms, 1050 @ 8 ohms
Inputs: 2 x XLR, 1 x stereo RCA, 2 x 1/4"
Outputs: 2 x speakON, 2 x Binding Posts
Cooling System: Efficient Forced-air Fans
DSP: Yes
Filters: Yes
Rack Spaces: 2U
Height: 3.5"
Depth: 7.7"
Width: 19"
Weight: 8.6 lbs.
Manufacturer Part Number: NXLS1502-0-US

Crown XLS 1502 2-Channel 525W Power Amplifier For Sale - US Audio Mart

Hey guys. So my hobby (actually now more than that) is building acoustic guitars. I build them very light and use quality tonewood, so the sound is very clean and pure.

What I'd like is a PA type amp for my home and also to use outdoors (my veranda), to amplify the guitar and singing. No high volume required, but would like at least 4 channels for guitar and voice. What I want most of all is a pure crystalline genuine tone. I want purity of sound starting at low volume.

So my question is: are there better options than sometihing like the Bose L1 compact, Fishman Sa330, also the Turbosound and HZ systems? Perhaps I just buy quality components such as mixer and speakers and make my own system? Would want some portability though.

This is probably a total noob question, but I have not been able to sort this out via internet searches.


I'm trying to confirm that my bass reflex port length is correct, I was going for 38Hz using a 2" port with an external flare, and the length is roughly 7.5"/19cm.


Figured I would verify this using REW and a UMIK-1, held the mic flush with the port and ran a measurement between 20-200Hz. The result was the blue line. A similar measurement without a port at all (removing the tube and the flange, holding the mic flush with the resultant cabinet hole) gave the purple line.


I had been expecting to see a hump at the tuning frequency around 38Hz, instead the blue line rises to 90Hz.


So either my figures for tube length are completely wrong, or I am misusing the measurement tool- can anyone point out what's going on?

Hi !

I'm looking for the service manual or even PS schematic. I already have amp schematic.

Problem is I just replaced all output transistors, (Sanken 2SC2922/2SA1216) and outputs warmed up quickly, but no sound in a few minutes then died. No Smoke! Won't power up anymore (Power light won't even light any more) Hope outputs are okay?

Thanks very much in advance!

Hi all, looking around the web for speaker design guides (trying to go back to basics a bit) and found this. So many odd ideas, I don't want to say too much yet until others have had a chance to enjoy;

3 Way Crossover Design Example

Would love to hear your thoughts!

Not sure if already discussed, but how significant is the contribution of a non-parallel wall in a tapered TL construction towards fighting the internal box reflected waves? As far as I know, the parasitic harmonics need as much as bouncing as possible to get caught the most into the stuffing, before reaching back to the driver or port. Is a straight TL considered evil in this aspect and if yes, how can it be fought without tapering? Adding some asymmetric construction inside, like braces?

Hi Everyone,

Can anyone help with the component values for the Linn Valhalla ?
What values have R33,C5,C21?

Regards Alex

Hello all,
I need help identifying a problem with the ML 26 preamplifier. I saw a slight smoke when I turned it on. I shut down immediately. After opening, it turned out that the 20ohm resistor in the control part of the positive power supply was burnt. However, it is still 20 ohms after measurement. Schematic attached. Maybe someone can tell me where to look for the reason. Any help is appreciated!
Br ,
Marek

Hi guys,
Had anyone upgraded the capacitors in Audiolab 8000P? If so, could you please share your experiences and any improvements you noticed in the quality?

Hi there guys,

Having been a teeny bopper and spent several years blasting sound from cars and to some extent having matured enough to start with my listening system.

As it starts now I have re-purposed my car audio system to be my “listening” system where I aim for quality.

The system is basic and compromises of a pair of 6.5” splits and 2 x 12” sub which was my December challenge powered by a 4 channel Amp.

Whilst I was working I do some deep thinking and as such have decided to go full DIY on a Stereo Amp and speaker cabinets.

For speakers I am swaying towards GR Research and have been looking at the Modulus 686.

I welcome all your valuable insights and advice.

I am completely new to this so please be gentle 😀

Cheers Al

Hi,
I need 0.75" throat horns for Meyer Sound compression drivers, model MS1010L. Meyer does sell them but for $250 per horn 😱

B&C ME7 is the ONLY one I found.

Are there no other 0.75" horns around?

I would like to ask about who had encountered a problem in Bose acoustimass 10 series IV like the active subwoofer speaker unit, the bass sounds at first but after a few songs, the bass went off, the bass goes back again after I replugged it to the mains. I thought that the problem was from the Sony Receiver but it wasnt because I connected another amp and the bass was there. I replaced the heat pads of the transistors inside with mica and thermal grease (cause I thought it was an overheating issue) but the problem still persists. I've checked the 2 embedded subwoofers and their fine. The components of the main amplifier are almost smd, please can someone give me some advice cause Im confused 🙁

Hi,

currently I'm building a hybrid electrostatic loudspeaker: a combination of a magnetic woofer and an electrostatic mid / high panel. I use an external MiniDSP 2x4 HD and two seperate power amplifiers and one pre amplifier to power this loudspeaker.

If I'm correct, the hybrid Martin Logans (for instance) use an integrated power amplifier for the subwoofer together with an inegrated DSP to filter frequencies to esl panel and subwoofer. But when looking at the pictures, I only see two regular loudspeaker input terminals, so I would guess you can only connect them to the output of a integrated / power amplifier. (not line-level)

I was wondering how DSP takes place? Is the power / amplified signal used for the subwoofer and if so, does it pass a DSP? I hope my question makes sense as I'm interested in a similar solution for my own DIY hybrid loudspeaker, just to make it more compact.

This is a 2005 model. Board is PC-5445-B.

I need a schematic if anyone can help.

This is the first time I've attempted to build a FAST and I am wondering if there are any hard and fast rules? For instance how does one determine the placement of the drivers on the baffle, is it similar to mounting a mid-bass and tweeter? The FAST builds I have looked at seem to be crossed over in the 200 to 500hz region so any help with the crossover point and other parameters would be much appreciated. I will be using a MiniDSP 2x4HD for crossover and tuning and I have a UMIK1 for measurement.

This project is an evolution of the Nautilus tapered transmission line for full range driver idea I had. The drivers are a Wavecor FR090WA02 3-1/2" Aluminum Cone Full-Range 8 Ohm: Wavecor FR090WA02 3-1/2" Aluminum Cone Full-Range 8 Ohm and a Scanspeak Discovery 18W/4434G-00, 7" Midwoofer, 4 ohm: Scanspeak Discovery 18W/4434G-00, 7" Midwoofer, 4 ohm

Thanks for any replies.

Just a heads up for those who may be interested...

Next Thursday (Jan 21, 2021 @ 11am Central Time) I will be going live with PURIFI Audio co-founder Lars Risbo via YouTube (see link below)! This is gonna be awesome!


Join us for a Q&A regarding the tech behind PURIFI's unique transducers plus a quick view of their in-house analyser they built as part of the project. Given that Lars is +7 hours ahead of me we will be doing this at 11am Central Time.


I'll have some questions of my own but if you are able to join and ask some, please do. Let's show Lars support for being so willing to take time out of his busy schedule to help educate us all on transducer engineering and to share some cool insider bits of info.


See ya'll then!



Live with PURIFI Co-Founder Lars Risbo! - YouTube

I am planning to build a speaker enclosure out of mortar. If it comes out of the mold in one piece, I should get a seamless enclosure except for the front baffle. But does going seamless improves the sound quality, or are there too many variables, one simply can't tell?

Hi there,
I am completing parts for MX50 SE amp. PSU is the place I have most questions.
Transformer I have ordered will be 2x25V 250VA . Amp will drive 8ohms speakers. This power will be enought, even 25VAC after rectification will excees power and my listening volume needs.



Now my concerns regarding rectification. I don't want to wait for shipment of some kits from China but I see mostly two options in peoples projects.

8x2200uF such here
or 4x10000uF like here.

I am thinking about making two separate rectification boards , one for each secondary winding and MX50 module/channel. Now - will board with full bridge rectifier and 2x10000uF will be OK? Or better do it on 4x2200uF ?

I can purchase board like attached and I could arm this with two 20k uF caps.
I really wanted to understand how to calculate it, even simulate in PSUD2 software but sooner I will go crazy as simply I am not fluent in this matter yet.

It seems those values are simply that I can "go for" but I'd rather make sure and I like to understand.
Thank you
Jacek



Thank you

Hello there,


You guys helped me tremendously when I put together a F2B preamp clone so I thought I'd shoot some more questions here, I'm still fairly new to tube amps but I learned a lot with the preamp build.


I've been using this Bogen CHB100 as a bass amp for about a year now. The only things I've done to it was replace the old-style microphone jack to a 1/4 inch jack for ease of use, and swap the 12ax7 tube for a newer one I had laying around. I really dig the sound I've been getting from this... it's clean but gives a nice distortion if I set the gain at 7-8 and keep the volume low. I understand people do more modding to these for guitar amps to get a more colored tone, but the clean-ness works well for my bass application.

However, recently I've been getting more and more distortion even with gain set low and regardless of volume position.

It seems the amp has the original 7868 tubes in it, as well as the original filter caps, and from what I've read one of these two could be the problem. I've wanted to replace both for a while now just to keep this amp healthy and avoid any spontaneous failures, so I feel like now is the time to do it, and if it solves my distortion problem, that's grand, and if not I'll address it afterwards.

The tube swap will be easy, I'm getting 7868 to 7591 pin adapters and going to buy a matched quad of 7591s to use, and all that makes sense to me. Replacing the filter caps is what I'd like advice on. Attached are pictures of the guts, and a schematic of the CHB100. On the schematic I have circled the four caps that correspond to the large brown caps in the pictures. Are these the only ones that I should be replacing or should the blue caps in the photos also be replaced?


Will these caps from Stewmac be the appropriate replacement? Sprague Atom Electrolytic Caps | stewmac.com (See 100uf, 350v choice for brown caps)

I have a heavy-duty resistor/alligator clamp setup that I made for draining the caps and have done that before, so know that I am being safe about this. I would just like opinions from those more knowledgeable about what caps need to be replaced and what exactly I should be looking for as replacements.

Any info appreciated, thanks so much.

Hello all,


Wondering if anyone has done tests to optimize the value of current compensation resistor (R39 on the attached schematic) to minimize the shift in amplifier bias setting with changes in the +B supply rail voltage. If so, what results were obtained.



I just ran a real world test on various values of resistor ( 0 to 91ohms) and found the optimal value to be 36ohms, which is much higher than the conventionally suggested value of about 13ohms for the 10mA VAS current being used. Interestingly this agrees with the optimal value which my LTSpice simulations predicted while designing the amplifier. At that time I suspected my SPICE simulation was erroneous since it did not agree with what I read in certain books on amplifiers.

I have a RMB1512 which some genius plugged into our 230v mains whilst set for 120v. This is largely a big pile of ICEpower modules which don't care. The houskeeping psu is conventional EI transformer (a little 2 watt sized thing) and it cared a lot. Anyone know the secondary voltages?.
V1<->0<->V1 and V2<->V2

Hi all,


I recently completed the kit build and am running the Cossor Black Plates per Victor's suggestion (as a starter set since I was not in a position to afford the Elrogs or Psvane ACME/WE's). I have about 40 hours on them now and think I like their sound, but because I am new to tubes (my first tube amp) I have nothing to compare them to. I have done a ton of reading about other offerings and am trying to decide what direction to go in as an alternate/upgrade to the Cossor. I'm posting here as I am specifically looking to see what others have listened to on the 8600S (or similar builds). My list includes: EML, Psvane ACME or WE, Linlai comparable, Audio Note, Takatsuki and EAT. EML seems to have the most reliability and best warranty of all tubes listed, so is high on my list. I've heard great things about the Takatsuki's but I do worry about reliability for such a steep cost on the Tak's with a warranty that isn't reassuring. I am not interested in the Elrogs as they won't fit under the cage which is essential for me as I have a dog and kids that could pose a threat when I'm not in the room with a yard stick in my hand. 🙂 Princess Sophia? Perhaps.

Any insights would be greatly appreciated, especially if you have experience with the same amp, since I understand tubes can vary in sound signature depending on what amp is driving them.


Thanks!

Hello all,

Does any of you know where I can find schematics for Audio Research Reference 250 monoblock amplifiers?

Thank you

I just finished totally rebuilding this MTX Amplifier. The amplifier ran fine outside of the case and heatsink for testing. As soon as i put the board into casing. Also redid the thermal pads to ceramic?
I could really use some help with this protection curcuit. Nothing is getting hot.

I'm dreaming about a project where BSC could be avoided and 1st order crossovers could be used, to achieve high sensitivity.

1. Two side to side woofers in a bipole configuration, close as possible to the tweeter
Enclosure: ML-TL

-question A, how high can I cut these? How about 200 to 300Hz for 7" midbass units?

2. Two 5" mid-range units in MTM configuration. Being the same impedance as the woofer's and same sensitivity. Enclosures: sealed or dampened quarter wave

-question B. Baffle width gets tricky, isn't it? I need to make it wide enough to avoid baffle step roll off soonest than woofer roll off.

3. Lowest roll-off of the tweeter as possible. I'm aware of the right lobing of MTMs.


What kind of other problems and difficulties should I expect in such project?

I came up with this idea after buying a Stax headset and energizer.
Would it be possible to use them as tweeters in speakers, say above 4 KHz and therefore feed them with more power to achieve a decent SPL?
Any idea, comment or input would be nice!

Kind regards,

Willem.

Would like to get some Philips AD1256W8 woofers. Please let me know what you have and how much you want. Will buy singles or pairs.

Trying to find a ad1256-w8 woofer . Pls pm if you have one to sell . Thanks

I've done some basic searching and it seems to me that the sources for transformers suitable for tube amp projects (for Hifi) are in short supply in the US. And it seems to me that NONE of the "higher end" Japanese brands are available here at all (ie., Tamura, Hashimoto, Iso (Tango). Who do we have that build products that compete in that league? Or is Hammond right up there? Who else.


Can you folks list the manufacturers that are readily available in the USA for purchase?


Justin

Now i need some advise ....

Current set up in my house is a P3A dual mono at 48+48 rails with 1302-3281 outputs @50 ma bias ....

Ok rails are a bit on the risky side Load also is low about 5ohms so i kept the bias low
Listening demands are very low i think that the average power needed should be no more than 20 W
Obviously i know i am out of SOA but since i operate the system and no one else will abuse it i might get away with it ....

Now my actual problem is bias meaning that amplifier plays superb when warm ,,,So given the conditions above if i crank up the bias @100 ma i think i am pushing my transistors way too much ...Often i power up my amp in the morning to go home in the night to listen ....or i keep it always on the weekends

remember i live in Greece so in my home as we speak temp is 18-22 degrees but in the summer time it could easily go 35 .....

One solution will be to go for 1216 combo .... 15 MHZ more faster( 40 instead of 25 ), 17A instead of 15, and generally better SOA , also LAPT technology ....

any ideas ? Lowering rails or adding more transistors is out of the picture ...

Which chassis has the larger/more effective heat sinks:

Dissipante or the Deluxe?

- anyone having experience with the subject or who just wants to leave his critical comment concerning the sound quality within the limiting factors given is pretty much welcome to discuss the pros and cons of the active assists -

I am planning a too small box for a 2-way topology speaker.* My very personal domestic acceptance factor** allows for about 45 liters, gross dimensions being centimeters 60 × 34 × 30 (H×W×D). This is too small for a pro driver which is supposed to do the work from ~ 1.2/1 kHz downwards. There is two solutions to my knowledge, given the box volume is set and the topology is not changed:
- 1) A Linkwitz-Transform shelf-filter EQ of a sealed enclosure. Can only be achieved true active.
- 2) Parametrical equalizing of a vented enclosure, Q=2, slightly above very low tuning frequency. Can be achieved active or passive + EQ. Don Keele wrote about it 1975, AES paper attached. Lowcut is necessary to prevent high cone excursion below tuning frequency. This leads to very high group delay in low frequencies.

With the Hypex Amps both can be done. Before I chose to go active because of the time alignement of the drivers, I found the FaitalPro 12PR320 driver to be a very good choice for the woofer. Vented was still the idea then. Taking this driver as a start for comparison of both solutions, the question is what happens to sound reproduction. Here are two examples which take the Xmax of the driver as the limiting factor and power consumption on the other hand:***

Example for Version 1), a LT sealed:
If the LT is set to F3 @35 Hz, cone excursion peaks at 25 Hz and 7.3 mm within Xmax with a system input power (Win ISD) of 8 watts which translates into ~ 85 watts drawn for bass reproduction on each channel. Group delay is ~ 20 ms @ 20 Hz. 95 dB will be reached at a listening position 2.5 meters from the speakers (couch).

Example for Version 2), Boost-Cut vented PEQ:
With a box tuning of 30 Hz, a Q=2, +10 dB @ 35 Hz, 21 watts would be maximum system input power before Xmax is reached, but the amplifier load is already exceeding the specifications of FA123 bridged-mode (125 watts into 8 ohm), so it has to be limited to 16 watts system input power to avoid clipping at 125 watts amplifier load for bass reproduction. Xmax reaches 6.1 mm below and 4.3 mm above tuning frequency. SPL at listening position is naturally higher than Version 1 at 98 dB. But Group delay exceeds 30 ms below 20 Hz, up to 35 ms!

This means: version 1 (LT-sealed) is fundamentally limited by Xmax, while version 2 (vented PEQed) with a +10 dB @35 Hz is limited by power alone. But it needs considerable amounts of power to be extended to reach Xmax (165VA @ 35 Hz or 16 watts system input power, compared to half the peak value of 86VA with LT). Then, it could play up to 99 dB at a 2.5 meter listening position, whilst Group delay reaches 35 ms at the threshold of low frequency audibility at 16 Herz. This can easily be audible.
Also, for very high listening levels bass extension can be sacrificed (which can be done with switchable presets within FA123, either as a decrease of EQ boost or as a higher-F3-Linkwitz transform).

The trade-offs of both designs:
- Lower Group Delay (V1) versus less Cone Excursion (V2)
- Lesser Power consumption (V1) versus higher SPL (V2)

Is there measurements available on the impact of LT/Low-Boost EQ on distortion? I would like to see the rate to which it is rising with increase of Xmax and power. I suppose cone excursion will affect higher frequencies as distortion, what sort of distortion? Intermodular? The vented version can be louder but it has a much higher group delay which may be audible, although it is reaching critical levels very low and exceeds them at the limits of low-frequency audibility for Humans. Do you see other trade-offs which I did not mention? Which direction is the compromise for better sound in your opinion?
________
* CD + horn/waveguide and 12-inch pro woofer, each a Hypex FusionAmp 123 plate amp. So far, so conservative.
** Not related to my partner or any person I would share the appartment with. And not at all to the their gender, as this is not the reason why I would not want to build a ridiculously large monument into my own living room.
*** The driver has Xmax 7.5 mm and high power handling. The Fusion FA123 in bridged mode has a good amount of power too (~125 watts into 8 ohm). The driver (EBP 107) can therefore work in a sealed enclosure, Linkwitz transformed, or in a vented enclosure EQ-boosted.

Am I really going to try repairing this? lol
It’s possible, but time consuming.

I’m looking to build some atmos speakers for my room. They will me mounted about 8ft up on my wall. The rest of my speakers I’ve built for my set up have used the Dayton RS180-8 drivers and peerless tweeters. I’m looking for some ideas and plans for this build.

I split my amplifier into two chassis for a myriad of reasons but now I don't have access to the voltage I need to run my led power indicator. I was thinking running it off of an AC heater circuit I have would be perfect given the ac signal being close to 3 volts due to the diode effect of the led.
I am a little concerned with introducing noise since the led will be switching on and off at 60hz. ( or maybe 120hz?)
So is there an easy way to isolate it so it can't put any noise into the heater line or am I worrying about nothing?

Jeff

I’m going to be bringing home some JBL 4315s soon and was considering building a NP FW to drive them. Any recommendations? I have built the ACA but want more juice for this project. I think I’d like at least 50 watts per channel, maybe even up to 100, is this f5 territory?

I'm new to the world of DIY, but have been into Hifi for more than 20 years, I currently have 2 separate systems, my main Linn Akubarik stereo system, and a secondary Linn Majik surround sound set up used only for TV duties.

My general approach is to build a DIY replacement for my existing setup which improves on the sound quality - main aim is to replace my stereo setup.

To get my DIY career started and learn the ropes I thought a "simple" bookshelf build from an existing design would be a sensible idea.

being new to the DIY world, and not knowing anything about pros/cons of drivers I'm struggling to pick a design which is going to provide an improvement over the Majik 109s. I've looked at a number of designs which seem sensible but I've got no idea how to pick the right 1 for me.

would be good to understand how to go about picking the right design.

thanks in advance!

Second pair of drivers to sell. 2021 will be the year I will STOP DIY.

A pair of AudioTechnology 18H52-17-06-SDKA.
NEW.
Box opened jut to take pictures.

They are a special order from AT and priced to 350€ each, the SDKA (Kapton-Aluminium voice coil version)

I will sell the pair for 400 euro + Shipping + PP fees.

they are the perfect pair fro the Scan Speak Revelator D2905/990000 tweeters I have for sale in another thread, and both are the drivers for Jeff bagby's Spirit Winds

Hello,

For sale is a pair of utc A-20 transformers. Asking $175.00 for the pair.

Thanks

I got my speakers for free from someone who was moving house and had to get rid of them quickly.



They're Mordaunt Short MS55ti.

They have x2 8-inch drive units (each side) and a titanium tweeter. Non-ported cabinet.

I'm fairly happy with them but as for any hi-fi person I'm always looking at ways of improving things and just wondered how good the MS55ti is and how much I would have to spend to get something better?

I would like to get your opinion on the recommended grounding scheme for an amplifier that has more than one power supply with separate transformers.
Let's say 2 transformers with the corresponding power supply board each.

Over the last few days the Edcor CXSE 25W prices jumped from $93 to 103. Bummer.

I need a pair of Acoustic-Dimension LCR transformers
New or used

Hi All


I need advice to get my old sub back in game.


Some 15 years ago I built HT DIY subwoofer project following some advises from community.
Driver used is visaton tiw 200 XS
TIW 200 XS - 8 Ohm | Visaton


Box is BR app. 54liter(brutto) box made from 25mm MDF with double internal bracing.


At the beginning I was happy with sub for HT but my neighbors not so.
As I have grown older I found out that I like this sub more when I close bass reflex port with some foam.


Few years ago plate amp on this sub died and I stooped using it.
Now that I got new nice L/R/C speakers, KEF R3, R2c I would like to put it back in game.


This time I would like to have closed enclosure as I think it will be more controlled and I need only just a little help for my front speakers.


Can you advice if I need to make enclosure smaller or just fill it with some dampening material as I reed on drivers web page for closed enclosure advice to be 30 l/closed--46 Hz/0,68enclosure but mine is 50l at the moment.
I plan to simply close BR tube with foam.


Sorry for my English


Thanks

Sold, These are in very good physical and operational condition. These sound great driving my AN super 12's. Very low hours.
Mismatched power supplies as one original failed.
220.00 plus shipping. They will fit in large priority box for a think 20 bucks.
Thanks Old Big

Have a JL Audio 450/4 amplifier here on the bench which is completely unresponsive and shows no lights at all. I have read the few 450/4 posts on here and most of the other JL amp threads also but was not able to find a solution to my particular issue. The power supply fets for the front channel and their 47ohm resistors were defective and have been removed. All other power supply and output transistors are reading ok while mounted on the board. There was some corrosion on the bottom of the board but I had already cleaned it off before I read about that in some posts. Not sure if I have any vias that need repair.

Can I power up the rear channels alone with the ps fets for the front channels removed?

This amp is using IRFZ44R. Can I use IRFZ44N or another equivalent fet since IRFZ44R is unavailable in my area?

Using another post as a guide, I am posting the voltages present on the LM324M and the 6 points asked for concerning the remote turn on diode and associated resistors. I did notice that my readings on Pins 13 and 14 are different than most, 13 is low while 14 is high.

LM324M
1) 0.62
2) 6.66
3) 4.03
4) 12.31
5)6.69
6) 5.91
7) 11.04
8) 11.09
9) 6.61
10) 9.60
11) -0.00
12) 4.23
13) 1.65
14) 10.94

2203 resistor
1) 9.61
2) -0.00
2201 resistor
3) -0.00
4) 10.85
Diode from remote terminal
5) 11.53
Diode next to it
6) 6.65

Hi,

I am trying to build a speaker with the SP Acoustics SB13PFC25-04 woofer and Dayton ND25FW-4 tweeter. The goal was to keep the components below $200 for the speakers not including the enclosure.
By the help of one of the forum's member - Mayuri i've come into a crossover design and enclosure that was fixed to ~15liter

One problem we saw is that the total impedance is relatively low - ~2Ohm which I should increase (it will be connected to a tube amp 10W/ch). I've read that adding in series a resistor will help increase the impedance but will add some distortion ?!
Any additional comments and/or recommendations will be welcomed.

* I have no tools to measure therefore all the design will be based solely on simulation and feedback


Thanks.

I have a sm57 which I use to record with. However I don’t really have a proper pre. I would like to build my own without IC chips. Ideally something like a MOSFET. However, I would also like it to have a transformer.

Are there any simple schematics or layouts for something like this? It doesn’t need phantom power. Just a simple simple single mic pre for a dynamic mic, no IC, and a transformer.

I have tried to look for something, but no luck at all...

In fact, it is hard to find ANY layouts/schematics for mic pre’s, especially compared to how easy it is to find guitar pedal circuits!

As awful as the COVID situation is, it has allowed for some unique opportunities for me and maybe for others.

I'm in a high-risk group so I've been especially isolated since March but I work in an office that is completely locked down except to my wife and myself, we have the place to ourselves. We moved in our exercise bikes, a toaster oven and its more or less become our livingroom/workplace. We bring our cats even.

So to complete the setup, I moved my main audio system in which has given me extensive listening time. Roon / Beyma TPL-150H / 12P80Nd / MiniDSP SHD and a pair of $50 TI TPA3251 based amps. I know the amps are not special but it has been a very special experience to be able to listen to music all day.

My wife tends to work in the lab area so I set up a system for her today. OkaraOW1 with Hiquphon OW1/Vifa P13WH, MiniDSP DDRC-24, a friend's loaned turntable, an antique Radio Shack phono pre, 2x ACA amps and a ridiculous collection of adapters to make it work. Just tuned the DSP by ear and it's fine, not critical listening.

I know many are not so fortunate as we are but I hope everyone is making the most of what they do have. Happy new year.

i understand that many like very fine capacitors in their crossovers but how poor are electrolytic caps like m.d.l. sold by jantzen? my speakers are always short lived so if caps change their values slightly over time is nothing that bothers me, and series resistances of 0.2-0.3 ohm does not bother me either, what else is poor with electrolytics caps?

Hai Friends...! I have 4 pcs 2SK 725 and 4 pcs 2SK 727. I want to bulid Class A Power Amplifier with these Mosfet but I dont have Circuit, can you help me please...?

Recently retired and now looking to build speakers and possibly an amp or two. I joined a few years ago but I am now, as I like to say, ready to get ready to go.

I am a woodworker, Deadhead, curler and ex-runner (now I walk). I am also an electrical engineer but haven't used my education to any great extent. I was an industrial heater and temperature controller salesman in my career so I did use some of my engineering background but I refer to heater power calculations (think kilowatts) as big electrons where as circuit design is little electrons. Whole different mindset.

I have built one set of bookshelf speakers and a subwoofer that sound good enough to me to want to do more. We shall see.

Tim

Interesting paper: https://core.ac.uk/download/pdf/11458689.pdf

Using multiple paths with phases shifts.

Anyone tried this with valves? (Yes I’m aware of the duplication)

Also: https://link.springer.com/content/pdf/bbm:978-94-009-5770-1/1.pdf

This circuit is autonomous and does not need any external support to work. It is based on the well-known timer NE555 and an NTC which could be changed according to the size of the transformer. When the power switch is turned on, the mains voltage passes through the NTC while at the same time the NE555 is triggered and the blue LED is blinking for 1.5 second. After that, the output of 555 is turned steady ON, it activates the power relay which in sequence shorts the NTC and so the mains voltage passes through its contacts. The blue LED now is turned ON. This circuit is very rugged and tested for 12 years of problem-free operation in any condition.

Dear all,

Whats-App-Image-2021-01-06-at-11-50-48-AM — ImgBB

Good day to all. I have a pair of ARC M300 power amp. Refer to the image attached, this is the faulty transistor that i unable to trace the part number. Even i have check the schematic diagram in the service manual, there is no stated any part number for this transistor. Is the color is an indication for the part number? Anyone if came across this issue or have any idea to solve this, Appreciate if you can help me.

Thank you very much

Regards:
Harry

Hi all I have a Phoenix Gold eq2125 which isn't powering on. Could the Sg2525a be at fault? The input voltage is reading 3.5v DC.

Anyone has built this speaker?

GRAND ORGUE | Visaton

Any comments? Is that good?

For sale is one pair of UTC LS-12 MIC / MC Phono Input Audio Transformers.
All Coils Are Tested.

Physically and cosmetically in very good condition.

Check attached pictures for the UTC Terminal Pin out.

Primary Side is 50/125/200/250/333/500/600 ohm impedance.

Secondary Side is 120K ohm impedance.

It can be used as MC step up transformer as well as MIC line input transformer.

Worldwide airmail shipping with tracking number.

Price: 500 EUR + Paypal fee + shipping

Hi All,

I recently gifted away a pair for Wayne 4Pi Speaker Cabinets and in return, the person gifted me a vintage set of ITT LPKM 130/50 2" mid-domes.

Look through my driver inventory, I realized I had a pair of Dayton Audio RS225S-8 (vintage shielded version) and Peerless DX20BF00-04 tweeters.

With the parts on hand, I proceeded to build a ATC lookalike mini-monitors, with offset dome mid and offset tweeter.

As I take measurements of the ITT (using sweeps via ARTA) - I hear some sort of resonance / odd tune to the sweep between 100hz -700hz, and thereafter the sweep sounds more normal. It sounds tube-y - if that makes any sense. Perhaps I can record in on my phone and upload it to Youtube if that helps. Almost as if the diaphragm is ringing at certain frequencies. One would have to listen for it using headphones.

The mid's resonance frequency is approximately 250, but despite crossing the mid at 800hz - I still hear it. I've even tried including a parallel LCR circuit to suppress the resonance, but I still hear it.

Can fellow forum members help me troubleshoot the issue? Let me know what measurements I can provide (e.g., distortion, near-field with and without LCR, CSD, etc.).

Wanna try pentode based ccs for 12ax7 on cathode follower part of it, after good results with LTP on PP amp.

Should I even try? Which pentode for 1-1.1ma current is good to play with? Maybe ef86?

There are 2 scenarios, one where i adjust the tubes tightly so they vibrate less and the other where i dont so they vibrate a lot, i dont know how they sound so i would like to hear your suggestions

After realising that I will not have time and energy to build it, I will hesitatingly part with this.
Included is:

the Modushop 5he case in 400mm depth with 10mm black front, 3mm aluminium floor and second perforated iron floor panel
The heatsinks are not predrilled for the brackets, which are included.

Almost complete Mouser BOM parts, max 10 resisters are missing, because I wanted to use very good ones for input circuit. Mostly brown dales, Silmic etc. It's possible that something else is missing, but unlikely and at your risk.

10 BHC power supply caps 33000uf, they have 4 pins

Supply and circuit PCBs

Matched Toshiba transistors from Spencer

And finally the V-Fets matched by the master himself, and the rest of the kit including mica, goop, mounting parts etc as it came.

So a complete amp kit, just some resistors missing and transformer of course.


Because I have no idea what I paid for all this , calculate for yourself and make a fair offer. Only selling the whole lot together.

Shipping to EU preferred because of less hassle...

Hi forum!
So i got these two fe87e on an online auction the other day. They where just too darn qute to resist! They came in a couple of tiny closed boxes of about 1L. I thought I would put them in a 5L BR like fostex recomends, or something similar to see what people are raving about.

So I hooked them up in my kitchen to an arcam solo to check them out and yikes! They sound awful! I let them play for a couple of days and things improved a little. One of the drivers sound quite ok now. Way to bright and a bit edgy in the mid range, but not terrible. The other driver is even brighter and almost completely lacks mid range.

I noticed that the fabric surrounds have aged quite a bit. The "better" driver has a little tack left but not all the way around. Some parts have no sealant left and i can see through them. The "bad" driver has no tack at all and it looks like there is almost no sealant left at all. Could this be the issue? They are however still soft and not dry. Otherwise they look ok. The cones seem to move freely. One had had the dustcap poked in but pull out again (the "better" one).

Any ideas on what could be the issue here?

hello, this is my first post and have some questions. How can I modify a car amp's power supply so that it can safely operate at 24 volt vehicles? Usually, the p.s. mosfets are irfz44 and switch ic used based on tl494. Can the mosfets handle the double voltage? thanks to all replies...

I am looking for guidance on a series crossover question. I know it is critical to be aware of dcr in inductors, but I'm trying to keep costs low. My inductors, I have two, is valued at 2.56mH as part of a 3way second order. So, in the past, I used laminated bar inductors for large values (5mH) and saved $ over the cost of foil or Litz inductors of similar values, but they were destined for parallel crossovers.
My concern is drc values and saturation of the laminated core inductors. Thought?


kingfisher