I have an Yamaha RX-V357 that suddenly stopped working , no protection mode , no display , no diag mode - only power relay toggle (clicking on and off).

I've already disconnected power stage voltages in order to avoid any output / speaker DC protection and also power relay is by-passed in order to have all voltages ready-to-be-checked from power transformer.

Almost all voltages seem to be correct, except 5MS that missing. If 5MS externally provided no more relay clicking but still no display.

Any help ?

Helo,guys ! How can I control DC loutput offset of STK 403 , I have an Yamaha-rx-v357 and all STK have 1 V DC offset on output, otherwise sound is clear if protection is deactivated...

I've found on Google : "I found that the +/- Pre voltages were very important in setting the DC offset on the output."

On Yamaha-rx-v357, what does it mean PS PRT:16% - wich is normal range for it, wich is IC 242 pin for it , wich is the reference for it ???

The circuit on attached is a contour (variable loudness) circuit of Nakamichi 410 preamplifier. I’m wondering that why they used two sets of 22uf capacitors and 100kOhms resistors; C501, R501 and C503, R503. Are these components be buffer circuits? And why didn’t they place them after the switch to reduce the components, using only one set of R and C instead of using two for IN and OUT switch position?

Hello,

I bought a re-furbished pre-amp which initially worked fine. Then I replaced the tubes and something got messed up

EST » TOOTEKATALOOG

This is it, a MusicAngel device using 12ax7 x2 and 12au7

I replaced the original tubes with 2x Tung-Sol 12AX7 and 1x Electro Harmonix 12AU7EH

There was only really quiet sound from right channel. When I put back the original tubes, the sound came back but was crackling.

Did I break it?

Thanks for any response!

I find their approach is very interesting.

http://www.grimmaudio.com/whitepapers/speakers.pdf

1. EQ the drivers beyond operating range to flat

2. Apply the intended crossover, eg. LR4.

3. Apply time delay.

So far so good. But what about this 4th step, quote ..

Finally, the icing on the cake. The sum of an ideal LR4
system is a second order all-pass with a Q of 0.7. In order
to avoid the problems associated with correcting
phase exactly, build an inverse all-pass filter based on
the theoretical ideal. This filter will be non-causal so
there’s a good reason for using FIR.


Questions:

- What do they mean by " The sum of an ideal LR4
system is a second order all-pass with a Q of 0.7" ?

- What do you think " an inverse all-pass filter based on
the theoretical ideal" ?

If this can be realised using MiniDSP it would be great I think.

I have a number of speaker leads on hand, but one particular pair of leads have copper coloured multi strand wire in the +ve path, and silver coloured multi strand wire in the -ve wire.


None are magnetic.


Is this an issue?


Could these wires have different conductive properties which could either affect sound or cause issues with electronics such as the Amp?


thanks


Cliff

Hello all and Happy New Year!

I am contemplating a new build, a subwoofer to complement my Frugel-Horn XLs. The Frugel-Horns don't necessarily NEED a sub to go with them, but I think they would benefit from one. I'm not looking for cheast-crunching pressures, just to give a bit more kick to the kick drums and some more groove to the bass lines. More than anything this is me wanting another project...

From an aesthetic point of view, a down-firing design would be quite suitable. It would also be the easiest considering there is a young puppy roaming around having a taste of everything with is very pointy teeth. In terms of acoustics? I have no idea.

I have Hypex DS1.2 amp on the shelf, which I'll happily use for this project. With the MiniDSP DDRC24 I expect I can pair the sub nicely with the Frugelhorns.

When it comes to choosing drivers or designs, I don't have much of an idea where to go to accomplish my goals. I'm hoping to find a ready, or easily modifiable design that I could use, somewhat like the Frugelhorns themselves were.

All input will be greatly appreciated!

I've built an amp similar to the two stage mono Bill. My issue is that when I load the output transformer the output voltage reduces significantly. The amp just can't drive a load, about 8watts max into 8.5 ohms (dummy load).
The HT is 460V, quiescent current 50mA. (GEC class AB1 ultralinear fixed bias conditions which should give up to 70W with anode to anode of 4k ohms)) Fixed bias is from Tent Labs auto bias circuit. I've also tried configuring as a basic cathode auto bias circuit, but the problem is the same (I don't think it is the Tent Labs circuit causing the issue). I've tested the driver stage when the amp is under load and it maintains its drive voltage. The output transformer is a discontinued Sowter 50W UL unit, 4K a-a, 40% taps, four output windings that can be configured for various loads. I've measured the primary winding dc resistances and they seem OK. I also applied 50Hz ac to the secondary and measured the primary (no loading) and calculated the anode to anode impedance which came out at about 3.8K ohm, a bit lower than that specified. I've tried configuring the secondaries according to manufacturers recommendations and every other which way, to try and get load tolerance, but with no success. I've also tried other, known good KT88's. I've tried varying the HT and bias with no improvement. So on the face of it, it seems a problem with the transformer, but if it is, the failure mode is odd as it appears OK on all static tests. Any ideas? Thanks. Matt.

Hi fellow audio mates
Can someone help me re-configure bubbleupnp server and necessary foobar2000 settings to have bubbleupnp up and running on my android tablet to control f2k?
Until recently I had everything setup correctly then I changed over to a fanless mini-pc and I can’t make it work any more!
Is there a step by step set of instructions available somewhere?
I have the bubbleupnp server installed on the same mini-pc along with f2k
Thanks in advance!

I am applying Dada mods to my Quad 405 MK-1. My boards are M12368 Issue 10.

Please see attached pictures of Schematic and board lay out from service manual.
Now compare it to Picture of board by DADA , specifically orientation of C2.

Which one is correct?

I have looked at different websites, like Keith Snook, deSmith etc and everyone advises to change the capacitor but no one advises to reverse the polarity?

Many Thanks in advance for your guidance.

Hello diyers,

Having a handful of kits under my belt, I am looking to embark upon my first scratch build -- a tube headphone amplifier based on the Van Waarde design, tweaked based on some comments from user audiowize in a thread here, substituting a 5687 tube and tweaking the plate and cathode resistors to reduce the gain.

I am aware of the limitations of OTL tube amplifiers in driving low-impedance headphones; my primary application for this will be driving 600 ohm Beyer DT880’s. I know this isn’t the end-all be-all of designs -- I like that it’s simple, with a relatively low parts count, and seems like a fun first scratch build project.

Here are the design constraints that I’ve set out for myself:

• Single-chassis design, preferably not too large (considering a 10” x 5” x 3” or 9.5” x 5” x 2” Hammond enclosure)
• 0D3/VR150 shunt regulator w/ MOSFET to provide the ~150VDC B+ (I need that beautiful blue glow in my life) based on this circuit and this thread
• Heaters to be run on elevated AC
• Solid state rectification
• Reasonable budget (as always, I have to set aside a large portion of it for new tools 🙂 )

I’ve attached the schematics and a screenshot of the PSU design and single-channel schematic.

I was planning on using the following real-world parts in the power supply:

• Ecdor XPWR262-120 transformer (225VDC @ 300mA w/ 6.3VCT @6A)
• Hammond 158M 10H @ 100mA open-frame choke

From my simple simulations, it appears that at quiescent current the L-C filter I’ve simulated in front of the 0D3 regulator will reduce the ripple to about 175mV (peak) and the regulator and subsequent 47uF cap will further reduce it to 100uV. (I substituted a Zener in the simulation because I don't have a model for the 0D3/VR150 tube.) The LTSpice sim shows only 45uV on the output.

What does everyone think? Am I missing anything obvious here? Any feedback is welcome. Will post build photos and tests as I progress.

So there are all sorts of calculators for port length/area/volume etc. but we're tuning for some very low frequency such as 32Hz which has a wavelength of 30-ish feet but the ports are designed to something much higher frequency. They aren't 30ft in a typical vented enclosure design. Sure, you deal with half wavelengths in room gain, but how in the heck can you somehow boost 32Hz with a tiny (relative to 30ft) port? If I guess correctly, the "1st resonance" is the actual Helmholtz resonant frequency of the port which makes sense...200Hz, etc., but it doesn't seem like you can get a resonance from ~3 octaves below that. A Helmholtz resonator resonates at integer multiples of half the wavelength (right?) and is why you get the crazy resonances at increasing frequency in (for example) Hornresp. Every frequency that is an integer multiple of the Helmholtz (1st resonant) frequency is a resonant frequency, but they have to be higher than the 1st resonant frequency. But to get a resonance at 32Hz from a resonator designed for ~200Hz means you're dealing with fractional (not whole number) multiple of the half wavelength.
I'm sure the explanation is simple. But what is it?
Link to the inevitable thread discussing this is welcome.
Playing with my new table saw with my son's new sub enclosure and still have 10 fingers (born with 10)...

Hi,

I purchased a used Stageline N Naim phono stage. I don't have other Naim gear or a PS for it. What's a good 24v PS to get the best out of the Stageline?

After opening the unit, I saw 10 of ZTX384/ZTX214 transistors per channel.

Some options are:
Jung/Didden Superreg
TeddyReg
Classic PS, similar to Naim designs.
and finally: Should I use a dual mono PS since the Stageine has a pair of "+ V in" on the the DIN connector? Is this separate power sources for each channel?

Thanks,
Herman

I decided to dive into the world of tube amplifiers by building one. I researched how they work, and found a schematic I would use as a starting place. I chose the AC-568 bassman, but I had some changes I wanted to make. I gave it a potentiometer on the tone slope resistor, added a mid control, and gave it a class A power amp. I only used the bass channel, and the input with a resistor going to ground. I added a 4th gain stage too, simply because I still had half of a 12ax7 available. The first time I turned it on a few things happened..

1. It hummed very loudly
2. the guitar signal was patchy, thin, and very distorted
3. It made a bit of a "pop" from the speaker and went quiet

A few hours with the oscilloscope narrowed it down to the 3rd gain stage, and more specifically the tube. there was signal through the whole line until the plate. I moved the wire on the screen of the 3rd gain stage to the screen of the 4th, eliminating the 3rd stage if I'm correct. I tried it again and now I just get really loud hum, and no signal. I haven't looked at it with the oscilloscope yet, but I can't quiet the hum with the ground switch or the volume. My best guess is that I have a ground problem, but that's just a guess. This is the schematic I drew, I know it's a mess but better than nothing. Bass amp prototype by adhehl | Upverter Thanks in advance for any help, sorry for the long post!

Hello,
While I'm quite happy with my "portable" player with 2 TPA6120 at the end, for best results at the main listening spot, I'm still searching for the best amp I can make. I was looking for a decent single ended class A design with transformer output, but yet could not find.

I had another project, started as low power guitar amp, but started on a hifi amp, again single ended class A with transformer output. During the project I realized it is a complete failure for guitar amp, so I built it as a hifi amp. It ended up very impressive. Not far away from my 2A3 PSE.
I also have an OTL headphone amp, with 6S19P at the end, I call it a monster and on cold evenings I was thinking to put it under my armchair, to have some additional heat 🙂
The 807 ended power amp makes less heat actually and it is very safe for the speaker (headphone).
Now, I was thinking, I put a 8 Ohm resistor load at the output and connect the headphone. It is heavier, but stable and less power hungry.
What do you think?
Do you guys have experience using tube power amp as headphone amp?
How would you make the load? I guess with several small resistor. For example 20 times 160 Ohm in parallel?
Thanks,
JG

Clearing out great quality small signal tubes that I have accumulated over way too many years! All of these tubes are new old stock in their original factory boxes. All test NOS on a calibrated TV10/U Navy tube tester. The pairs are closely matched and have balanced sections. (The Amperex PQ’s are the most closely matched.) I have a few pairs of each E88CC/6922 tubes.

Amperex E88CC 6922 PQ $100 per matched pair

Mullard E88CC 6922 Gold Pin $125 per matched pair **** all sold or pending payment****

Mullard E88CC 6922 $100 per matched pair **** all sold or pending payment****

Mullard E88CC 6922 Made in Holland, single tube $50

Mullard ECC82 (12AU7) $75 per matched pair **** all sold or pending payment****

Brimar 12AT7 (ECC81) $60 per pair


Buyer pays USPS Priority Mail. insured. Shipping to North America only. Tubes will ship within 48 hours of receipt and verification of payment. I will ship only to a verified PayPal address. Payment must be received within 3 days. Shipping cost is the actual USPS price. Please contact me if you have any questions before you offer. The tubes will be very well packed.

They are vintage tubes, so sold AS-IS. Sorry, NO RETURNS
[/IMG]

I have tried to attach a schematic.

This amp has a CPU which keeps powering off the unit. When I power the unit it starts and makes 65volts + & - about 5 seconds later it shouts down. In the diagram Q20 & Q21 are part of the Protect circuit and Q21 stays at 5V. Q20 has 65volts on the Base and Emitter and .001volt on the collector. I also replaced the 5.1 zener although it checked out.

There is .04 volts at the most on the outputs but I don't think that would shout it down. I did find diode D32 across the relay to be shorted and replaced it. I have also pulled all outputs and checked them ouyt of the board(they were fine).

Please help me with any ideas.
Thanks Jeff

good physical and working condition!
400.00 plus shipping and PayPal if used.

So does anyone have a photo of what this amplifier used originally on the power supply mosfets.
This amplifier had thermal spreader pads on the power supply mosfets.
And the tan silicone tape on the outputs but the blue sticky type tape still stuck to the backs of the transistors and the new tape, none of the outputs were seated properly.
Im just wondering if these pads are supposed to be on this amplifier?

Hi everyone,

First of all a happy newyear!

I'm working on my first speaker design. It's basically an MTM with the woofers in a serparated vented box.
Woofers: HDS-P830883, connected in parallel
Crossover: 3th order (see below)

I'm having some baffle step issues and implemented a bafflestep correction of 3db, after seeing the not-pleasing response I added them together to use as a 6db baffle step correction to see what this 'll do.

Paramters used to calculate the bafflestep:
ReVC= 5,85ohm/2= 2,925ohm (because they are connected parallel)
baffle width= 30cm (baffle measured left-to-right)

This gave as bafflestep values (for 3db attenuation)
R= 1,2ohm
L= 0,5mH

As you can see in the measurements of the woofers it seems like the bafflestep is just giving an offset mostly in the range of 250Hz-5kHz





Does someone see what's going on here?

Thanks!
Regards

Hi to everyone!

Do someone have the CROWN XLi 3500 schematic? I have searched in the web but found nothing about!

I appreciate any help with this schematic.

Thanks
opacheco

Hi

Not sure where to post this question.

I purchased a 2 channel circuit board online listed as a clipping indicator for preamps and power amps.

The LEDs turn on when only 1.2Vdc is applied to the signal pins (not sure if this is a legitimate test).

The board’s supply voltage is 15V.

I have tried to understand how the circuit function and came to the conclusion that there is an LED driver circuit with one transistor that reacts to the voltage difference between the rail voltage and the signal voltage, controlled by another transistor.

I am not sure how this board is to be used.
Is its power supply independent of the amplifiers or is it the same?
Is it only suitable for preamp level signals or amplifier level signals?
How does it work?

The seller is giving nothing away although I was kindly provided with the schematic. I deidentified the photos to avoid any issues.

Hi peeps ! happy new year.

well i talked to Gerald already about the transformers, and there are many threads about making one.

i managed to make several with different results in impedance presented to the amp so i know i can make one 🙂 (also tried different combinations prim vs sec, with the same ratio)

But i rather ask this question and maybe its a stupid one 🙂 but might save me time making 1000 transformers 🙂 looking for the holy grail that might not exist because of ....physics 🙂

People asked many times why not use a transformer instead of my traced ribbon (a ribbon with traces just like a planar magnetic) it looks like everyone including me thinks/thought it might benefit the efficiency.
But is it actually ? If by any miracle my transformer impedance would be 4 ohm flat (i made a few and got 3.7 and rising worked fine), just like my traced one here (almost flat actually not sure why it rises slightly) PIC1

would one be louder then the other ? the only reason i could think of is (weight) being able to use 7 micron alu or 4 and it functions as membrane and conductor. are there any others? since all the ones i made with different transformers etc are within 2 db compared to the traced version, that might be only the weight difference.

Only when i would dip under 2-4 ohm they would be much louder.... but that same would be te case if i made my traced one go so low.

i know with small true ribbons, tranny is the only way. but for long ones 90cm+ it seems to be not much of a difference.

am i missing something ? i mean current driven ok, but the amplifier will dish out the same amount of current in both occasions. 4 ohm with tranny vs 4 ohm without tranny, both have the same power going to the device in question

SIEMENS military NOS tube

6360 compatible with RS1029 CV2798



1 piece new NOS QQE 03/12 - for only 4,90 €

from SIEMENS with black plates ( 4000 pcs. in stock ) - as high grade military version, you will be not find a better one world wide. NEW in original boxes.

Payment terms: We accept PayPal only.

We provide tracking number after your payment. Shipping terms Shipping cost for every set worldwide is include.

We ship usually in 2-4 days after payment received. Insurance - max. 500,- € per Parcel.

Shipping terms Shipping cost for this up to max. 2000gr. DHL premium service is 14,- € worldwide.

Write email when you have questions or need special quotation: sales@be-tec.com

I am looking for silver plated interconnect cable - unterminated - like the one in the picture, I could not find it without plugs. Just 3 or 4 ft.

Please help.

Given all that Father Pass has done for us this annoys me greatly.

PassLab VFET clone Amp, 20 watts - featuring two pair of ultra rare Sony 2 SJ28 & 2 SK82 Vfets For Sale - Canuck Audio Mart

Regards,
Dan 😡

I bought this kit and built it: Dynamic&Passion Hi Fi XLR Balanced Single ended Preamplifier Board Valve 12AU7 Tube Preamp DIY Kit American ARC Circuit|tube preamp|tube preamp diypreamplifier board - AliExpress

This preamplifier is a true balanced design and requires 4 transformers for its full functionality

1 - one for the trubes that must provide 275 - 300V
2 - two transformbers for balanced /signle ended conversion
3 - another one to provide 14V

I commissioned edcore to build me a power transformer that provides 275,. 6.5 and 5v. I use the 275 and the 6.5 volt outputs in this build

i commissioned edcore to build two 600:600 transformers for the balanced to single ended conversion

i used antek for the 15v


I am selling the completed boards confirmed working plus the edcore transformers


click here to see the build:
Chinese 12au7 / 6922 pre amplifier finally working - YouTube

price is $99 for everything which is %60 he price of the edcore transformers and the completed boards are free but shipping will be between $35 to $55 depending on destination. I will not include the antek transformer.

I decided to use this between a soekris DAC and a class D amp to build an integrated but then decided to go directly from DAC to the amp and dont want the pre amp stage

no tubes will be included

i removed the volume controller and i did it a little rough. the board is not damaged but he flat cable that connects the included motorized volume pot to the bcb is destroyed.

RCA connectors are included but XLRs are not.















when ordering i paid them $40 extra to uplgrade all the film caps to vishay

Hello,
i have this amp with a burned output section..

I have difficulties to get new dual resistor: Noble Dual 2x0,47Ohm 5 Watts.
Emitter resistors..


Is it possible to take single resistors,or must they be thermaly coupled?

SOLD

I purchased this from Schiit 6 months ago. I used it for 4 months but changed to a different amplifier and no longer need it. It is in like new condition and will ship in the original box.
I am cytowing on ebay with 600+ positive feedbacks, never a neutral of negative.
$130
Price is firm and includes shipping in the continental USA. PayPal only.

This one seems to be getting some good press:

http://www.mother-of-tone.com/attraction.htm

See this review:

http://www.enjoythemusic.com/magazine/equipment/0506/zero_oversampling_dac.htm

Sounds like the second coming from the review. Anyone care to speculate what makes it special?

I would like to sale 6 pcs. 10uF and 3 pcs. 5.6 uF Miflex Copper foil paper in oil capacitors. This is the best Miflex product and one of the best you can buy. In excellent condition 9/10. The price per pcs. is 250 US$ for 10 uF and 200 US$ for 5.6 uF plus post cost to your destination. Location Slovenia Europe. Contact: bpolak8@gmail.com

Humble Homemade Hifi - Cap Test

Helo,guys ! How can I control DC offset of STK 403 , I have an Yamaha-rx-v357 and all STK have 1 V DC offset on output, otherwise sound is clear if protection is deactivated...

I've found on Google : "I found that the +/- Pre voltages were very important in setting the DC offset on the output."

my amp is power up, i'm getting harmonic sound, when i put an input jack in and a bad humming out the output. need your help please. thanks i try to up load schematic.

Full disclosure - I'm more of a vintage computer guy, and I'm very much a noob when it comes to audio stuff.

So I have a set of old PC speakers that I like the look of as they match my old computers, but they're pretty much toast. Even when they were brand new they wouldn't have sounded too good.

So in short, I want to rip all the guts out of them (amp, speaker cones, etc) and replace them with something newer and better sounding. My problem is I have absolutely no idea where to begin. I've tried looking up guides and tutorials online, but there doesn't seem to be anything I can find for what I specifically want to do. (Speakers AND amp all together in one unit)

Here are some pictures for what I'm dealing with:


20201203-192328 — ImgBB


20201203-184428 — ImgBB


20201203-184345 — ImgBB


20201203-184343 — ImgBB


20201203-184337 — ImgBB

(The knobs have already been removed from the pots in these pictures)
Note the plastic fake dummy tweeter!

It looks like something that should be in theory straightforward: just source equivalent components and swap them out!
However, I just have no idea how to evaluate what is suitable and what's not.

Some specific concerns of mine:
* Make sure the pots and power button line up
* Make sure I can hook up the power LED
* The amp board needs to accept the correct input and have an output to go to the left speaker
* What sort of power supply do I need?
* Does the amp need special separate outputs for the woofers and the tweeters?

Since this will be hooking up to old computer hardware, I don't really need absolutely top of the line components, but I still want it to sound reasonably good.

So I would really appreciate some help, just getting me on the right path. I don't mind doing my own research, but in this case I just have no idea where to even start!

Hi my friends,

I have a problem with my Yamaha RX-V 550, the amp turn on 1 second and then turn back off.

When I started on the diag mode, I have this message : PS PRT : 000 D

I guess that the problem came from the power supply board or from the big transformer, because when I unplugged the cable that come from the transformer to the front up lever board the amp turn on normally in straight mode.

It's difficult to me to explain my case, I did a little video that explain all that :

YouTube


Any idea ? I'm really lost :/

Thank you so much

Hello All, new to this site, and looking forward to hearing all comments and help I can receive. Not even sure if this post is in the correct section. But here goes. I recently acquired a used Yamaha rx-v2095 receiver at a garage sale for $10 (along with a few other things). Some things I keep, some I resell. Cosmetically it looks ok, but unfortunately I have the same problem others have had. It shuts itself off. At first I was hoping it was from the heat. It has been sitting in my garage since I got it,til I had time to bring it in and take a look at it.

Being the middle of the summer and an unavoidable heat wave, I'm sure it was pretty warm inside. After sitting for only a minute inside my air conditioned home, I plugged it in and turned it on. I heard a click,than a second later another click. looked at the display and saw nothing. I did this a few times with the same results,except that I noticed the display flash for a split second everytime I would turn it on again. I figured it was too hot and let it cool for a few hours in the ac. While trying it again later, no different results. After reading some other users posts, I decided to try some things.

I took off the top and did a visual of the inside. Nothing looked damaged or out of place. While turning the unit on,I would notice a quiet springing sound until the other click. I did attempt to run the self diagnoses. It did show me a message. I had to keep running the diagnosis over and over until I was able to make out the message,since it only displayed for a split second. It said CHK SUM: F300 G / PS PRT : 0%.

I figured before I go crazy taking apart things I don't need to, I would look for suggestions from more experienced experts than myself. I am by no means an expert, but I am fairly capable of testing and repairing all types of things. I can read electrical schematics. My main trade is automotive repair so I am familiar with evolving electronics. Thanks in advance for any suggestions you have.

I noticed the Sansui A-909 go in and out of protection so I measured the DC offset at the speaker posts. I got 25mv on right channel and 230mv on left channel. Where do I look to fix it? I know opamp NJM4558D has something to do with it, could the opamp be out of spec? The voltage amplifier is not the original STK3082 II going by the schematic.The one in it now is STK3102 II.

You know ho wit goes, you buy a mint, working PA-5 only to find when you receive it that there are 'issues' with it. I did not do my due diligence and purchase a mint PA-5 and CA-5 from someone on Craigslist without listening to them. Bad move. The problems are as follows:

CA-5 - sounds fine after cleaning the pots. I am missing the retainer ring for a knob so it does not 'click' into place when it is placed on the shaft.

PA-5 - here is where my issues are biggest. I was a broadcast engineer but have been out of the field for many years so I am at a bit of a loss on where to start. The amplifier sounds fine when driven with my McCormack and the CA-5 at low-levels of volume or with my iPad driven directly into the PA-5. The problems start when the volume is set over about 9AM on the CA-5 or 10AM on the McCormack and over 50% on the iPad driven directly. There is cracking, static and clipping with the sound reverting to 'thin' to muting to clipping on the RIGHT channel by way of the indicator LED. I am unsure the first step to take in diagnosing the issues. I also have a BUZZ near the power button that is not related to the physical power switch. It was initially not attached as the glue that originally held it had lost the ability to hold. I removed the front panel and after a bit of Gorilla Glue it is structurally solid. It seems the become louder (the buzz) after the amplifier is on longer and increases in level when more drive is provided to the amplifier.

I downloaded the schematics and I will look at it tonight when I put the PA-5 on the bench. I am going to start with cleaning the relay contacts (if they are not sealed) and remove a couple of input capacitors and check them on my Cricket capacitance checker. I am also going to check the FET's for issues short of removing them, although I know it is not ideal.

Any other thoughts? The buzz and clipping? Are they related? What would be the first thing to check?

Thank you in advance,

Darren

I have limited knowledge about electronics and still learning

DC offset is presence of DC at output which is bad if it is too high, after reading many posts anything like 50mv DC should be alright. I understand that a low DC offset is not going to kill any driver.

I was reading about Speaker protection and speaker failures(google), in case full DC voltage is present at output.
-Relays do not provide 100% protection.
-Somewhere it was mentioned to use bipolar cap between Amp O/P and Speaker I/P to block any DC, it was mentioned that a 10000microfarad cap will have not affect on O/P AC signal.

Question
1. Do bipolar caps blocks DC and provides 100% protection from full DC voltage at output?

2. If answer to #2 is Yes, do they have any affect on AC O/P signal from AMP?
3. If answer to #2 is No, then why doesn't everyone uses it to completely block DC from O/P?


My Primary concern/requirement/query is 100% DC Protection due to MOSFET failure or any other reason.

First happy new year to all.
LA4282 datasheet are available both from Sanyo and OnSemi
LA4282 pdf, LA4282 description, LA4282 datasheets, LA4282 view ::: ALLDATASHEET :::
LA4282 pdf, LA4282 description, LA4282 datasheets, LA4282 view ::: ALLDATASHEET :::

At the Digital-Piano DP-263 (McCrypt) of my friend - go to
https://asset.conrad.com/media10/ad...l-304303-piano-mc-crypt-dp-263-dark-brown.pdf
occurs a hard popping while switch-on since any weeks (no OCL circuit, i. e. caps in series to the speakers).

The reason was the shorted diode D1 around the mute control unit and the reason for this was again a bad design of the mute control circuit, because a small signal diode for charging a capacitor with 470uF without a serial resistor isn't a good solution - go to the first attached images and there to the first circuit.
One possibility is the use of a diode like 1N5407 (which I have currently realized as an emergency solution).

Because there are no application notes to this IC it is a bit difficult to find a mute control circuit with a sophisticated design.
After study several service manuals I have found this manual of LG television with chassis MC-014A - go to
LG MC-014A CHASIS Service Manual download, schematics, eeprom, repair info for electronics experts

The part of the audio power amp section of the LG chassis MC-014A you will find in the last (third) attachment and the part only for mute control section in the second circuit of first both images.

Here the necessary series resistor was present to limit the charging current for the associated diode. But there are other differences around the base of the transistor.
The MUTE mode in both circuit variants is active, as long as the transistor is in the conducted condition resp. is switched on (while troubleshooting I shorted C-E route of this transistor - therefore I know this exactly).


My questions are follow:
1) What is the task of Dx and the electrolytic capacitor around the base connection of transistor in the first mute control circuit (LG use only a resistor to the positive rail of 9VDC) ?
2) How do I convert the values from the LG-circuit , when I only have 5VDC instead of 9VDC as can be seen in the LG circuit from last attachment (maybe an appropriate modify according to the LG circuit is an approach, which operates better than the introduce of a high-current diode)?

Thank you for replies.

I have a pair of working mid-production-run Apogee Stage speakers PLUS two late-run replacement mid-tweeter ribbons [never used]. I’ve forgotten why Apogee sent me the tweeters, I think they were supposed to be woofer replacements. Been sitting in storage for ~20 years. I pulled them out today to test. The right speaker works perfectly & sounds glorious! Left speaker works well, but bass panel seems quite weak. The raw replacement drivers: one works perfectly, the other has no output at all. [I’ll check for cold/broken solder joints].

Wondering if anybody would be interested in buying any or all of them?

For sale two pairs (positive - negative) of Salas BIB shunt regulators
10000uf SMH UC electrolytic caps
Panasonic ECWFE 4.7uf Polypropylene film caps
50 ppm resistors (Dale 3W resistors are set for DCG3 requirements)
F30UP20S UltraFast diodes 30A
Soldered with Kester #44 63/37 and cleaned afterwards

SOLD

Happy and hopefully better new year 2021

I have the power amplifiers and PSU boards from an AMC tube amplifier and maybe play with the idea of using them in a DIY project. What makes me suspicious is that the cathodes of the power tubes are connected to ground via an extra winding on the transformer !? Since I don't have a suitable transformer yet, it will be difficult to find one with an extra winding. Can someone explain to me what the whole thing should be for? What happens if the cathodes are connected directly to ground as usual?

greeting

I have for some time followed various threads of multiple entry horns and finally got my own project started. However, I don’t have a quality table saw that a MEH project requires, nor the extra skills and tools needed, let alone a place to put it.
Perhaps I share this inadequacy with other DIYaudio members.
The following is my experience at designing and manufacturing Multiple Entry Horns as the Prime Mover in a Group Buy project involving a CAD/CAM process and routed by CNC to flatpacks like below:

Despite some cost doing Computer Numeric Control, we are very happy with the appearance and performance of the horns so far.
We hope the following can serve to inspire other DIYaudio members, and we shall strive to pass-on as many of the data aquired, as the project goes along, to hopefully act as a stepstone for a CNC MEH project that you may have in mind.

“Beloved child has many names” a DK saying goes, so let me start by dubbing my horn the “Rashorn” as part of my surname.
Instead of filling this thread with text and illustrations which take up space, and will take ages for me, you are welcome to my cloud at:

ME Horns by CNC - Google Drive

where I have put the final drawings and some pics., and posted this document as an evolving document, that I hope to maintain as the project goes on.
Currently, as you will see, the horn structures are ready, but the DSP cross-over is in an early stage.

Hi


I want to build a valve driven spring reverb using 6J1cheap Chinese valve pre-amp. The only reverb tanks available to me are rated 150 ohm input impedance.
Is it possible to rewire the transducer so its impedance is 4-8 ohms so the valve amp can drive it properly.


What equipment would I need to do this accurately? and would it be possible to use a multi meter to get in the ball park?


thanks



Oli

FS:

Brand new Monolith Magnetics IT-05 interstage transformer. Never used. Never soldered.

It is bifillar wound which yields minimum leakage inductance. However, the plage voltage could not exceed 350V per the instruction sheet.




Thanks.

I have a pair of EJMLC 300 horns driven with JBL 2450s crossing to a beyma slot tweeter at 8000hz but I have never really liked the top end.
I was wondering how high I could drive the horns with an alternative possibly Beryllium driver/ Yes I might need an additional extension.
Eliminating the tweeter would solve the problem of comb filtering.

I just found these two kits to put together but I need confirmation that it will work.

Meniscus has a continuum ll kit that I would like to pair with one of the woofer add-ons for a 3-way design. But.... the woofer is 4db hot in a ported design so..... WHAT IF I PUT IT IN A SEALED DESIGN?? The roll-off may just be what I need (fingers crossed).

Here is the woofers natural response in a sealed and a BR design.



The rise in the BR design was explained in the white paper to be too hot (bottom response) compared to the other woofer kit in a BR design (top response) which is more $$$.



So if I were to take the already hot BR design and instead use the sealed design and then side fire the woofer, would this work as intended? I believe this marriage could in fact create a useable flat / er response and still have a usable low end.?.

What do you think, will this work? Problems?

Here is the details. This is the 2-way kit...

Continuum II Loudspeaker Kit - Meniscus Audio

And here is the woofer... this also includes all the necessary passive XO stuff to add it to the Continuum kit (along with other kits too).

Kairos Woofer Module Bare Bones Kit (Pair) - Meniscus Audio

And here is the white paper in the woofer kit.

https://meniscus.lightningbasehoste...he-Kairos-and-Continuum-Three-Way-Writeup.pdf

I see there are quite a few folks on this forum who have experience redesigning crossovers for the various Kef Uniq speakers. I am considering using one of these drivers in a 3-way design, likely using a hypex fusion plate amp to provide power, crossover, and DSP.

I realize the r300 midrange driver would be the best choice here, but I'm not likely to find one at a reasonable price. I can find Q150, LS50, or R100s at a pricepoint I can live with.

My question is; if we assume

a) I'll be pulling the driver, making a new sealed enclosure
b) Using DSP for XO
c) Using a dedicated low distortion woofer(s) to cover <300hz or so

I also have a set of the HTS3005SE 'egg' speakers, but I don't think they are up to the class of the newer uniq drivers, if I remember the measurements I saw correctly.

Which of the drivers would be the best choice here, and why?

With a lot of research and several friend's help (yes, I am a beginner at this) I recently built the 4sUniversal tube preamp and lastly modded the 12au7 Bravo low voltage tube/mosfet hybrid headphone amp. To say I am impressed with the modded Bravo headphone amp mated to a pair of Grado phones would be an understatement.

If I could just get that sound in a line stage.

Rummaging through the net and ran across this 'Borbely balanced tube input mosfet output linestage single ch preamplifier PCB !' from Jim's Audio. It is a low voltage tube/mosfet hybrid similar to the Bravo. Have to try it.

Anyhow, after 4+ weeks of waiting the boards should be here any day now and I 'think' most of the hard to find parts have already arrived from ebay. (hoping these are real parts and not fakes) Mouser is super fast with shipping so the rest of the order awaits till everything else gets here.

It appears a simple, suitable, and reasonably priced +/-24 volt power supply is hard to find so I'm going to try and build this 24V Dual Power Supply Regulated | Circuit Diagram +/- 24v power supply.
Does this power supply look feasible?

What about the vol pot? I find considerable information about the headamp but very little information about the line stage. One thing it neglects to mention is the volume pot.

Does it go at the input or output and what resistance?


Any help on this project is appreciated.

GB: Maplin lateral mosfet pcb derivative

I have taken the 1980's Maplin 75 WRMS lateral mosfet amp and brought it up to date with modern easy to find transistors. I also added extra decoupling at front end to get around the hum problem some had.
The pcb allows use of TO3 or to247 packages.
The pcb has no copper below where TO3 transistors sit so it doesn't get shorted out by heatsink.
I have 7 pcb's now and if there is more demand I will buy in some more.
PCB's come with parts list, circuit diagram, build instructions and power supply wiring diagram.
Power supply needs to be +/-35 volts
£6.99 per pcb.
p+p is £2.25 to UK and £9.99 rest of world.

I am currently using a 3e Audio DSP as an active XO and I really like the flexibility a DSP brings to the table.

I have also been using a RPi with a HiFiBerry DAC+ and Mike Brady's Shairport Sync as an Airplay receiver for years. It works great with my analog gear but the DSP introduces an extra ADC-DAC step that I don't like. The RPi and the DSP both supports I2S so how hard could it be to make the RPi talk I2S with the DAC? Harder than I thought it seems... 🙁

Running the RPi as the I2S master seems tricky (MCLK not avalable etc.). It is probably better to let the DSP be the master and run the PRi as a slave using an I2S driver like this one by MKSounds or this one by Akiyuki Okayasu. But the DSP seems to operate in 48, 96 or 192 kHz with a 12.288 MHz oscillator and Airplay (and therefor Shairport Sync) is based around 44.1 kHz (using ALSA to resample in software might be doable but I would prefer a hardware based solution).

So the question is how do I feed the DSP 44.1 kHz through I2S from the RPi?

My guess is that I could replace the 12.288 MHz oscillator on the DSP with a 11.2896 MHz oscillator. I further guess it would slow down the core clock to 45.1584 MIPS and make the DSP support 44.1, 88.2 and 176.4 kHz instead of 48, 96 and 192 kHz. I don't mind being stuck at 44.1 kHz since I only plan to run Shairport Sync through the I2S interface of the DSP (I don't plan to use it for Bluetooth etc.). I am also able to de-solder and solder SMD at work so it would be a fairly easy mod but I would like to know if it might work before I actually start modding the board.

I asked 3e Audio about it but the answer was quite short and I'm not sure I totally get it, the answer I got was:

the DSP can change to 44.1Khz.please try and not change the 12.288Mhz crystal.firat to see if it can work.

Click to expand...

It seems like 3e Audio is telling me that the DSP can change to 44.1 kHz and that I therefor should try and se if it works without changing the 12.288 MHz oscillator. But I am still skeptical if this would work with the DSP acting as the master. And I am not sure how I could get the RPi to act as the master (it just seems like a safer bet to let the DSP act as the master).

I would happily try it out on the board I have if it wasn't stuck in my power-amp as my current XO. So I have to buy another board in order to actually try this out.

Another solution I guess would be to use another board with the RPi, something like the HiFiBerry Digi+ with digital out. But I would still have to somehow feed the digital signal to the DSP. Does anyone know of a working solution for adding a S/PDIF input (over I2S I guess) to the 3e Audio DSP?

I appreciate any help I can get to solve this problem. Thanks in advance and a happy new year to you all.

How good are these BG RD 50s when coupled to a good sub?

I have never used a layout tool. A little searching led me to KiCad.
OK, it works. Figuring it out. But it seems very frustrating that once you get a preliminary layout, it is not capable of rubber banding the tracks. Seems you have to delete the traces, move the part and then reconnect.

Wondering if there is another free tool, not WEB based, that has this feature? Or is that the kind of thing you have to pay for?

Ok so I am trying out some tube mikes with an ef800

Something like the AMI circuits UM47 Alt Tube Schematics


Now I also simulated this circuit and kathode current is around 0.7mA and plate voltage is around 14v....
Seems a little bit low to me but it does work.

Now even more strange. I accidently wired the kathode to gnd so there was no bias (zero grid voltage) but it just worked.
So I tried to do this in ltspice and indeed it keeps working.
Kathode current is 0.72mA (almost the same) and anode voltage changed to around 12v.
Maximum output and distortion was almost the same.


In real life the filament is only at 5.6v so kathode current will be lower and anode voltage will be a little higher.
The original U47 with the vf14 gave an anode voltage of around 35v.

So if we could leave out those 2 resistors, there is less components and if the filament supply has ripple it wouldn't get to the signal.

Would it harm the tube operating it this way?

Also why would we operate at such low anode voltage? (tube life? less noise? less heat?)

And it really sounds great using it this way....

does anyone know? they seem to be out of business

This is a simple PCB for CRCRC (or CLCRC) PSU for a small tube amp.

The size is intentional -- the mounting holes fit right under (using the same mounting screws) of an Edcor PT I plan on using.

Need some help with the grounding -- the intent here is to take the 0V point of the PCB and tie it to a star ground on the chassis, where the amp PCB and speaker outs will be tied to as well.

In this case, is it better to locate the 0V north of the B+ near the output cap, or does it not matter because of the pour?
If I remember correctly, the preferred place to tie to the chassis is the (-) of the first filter cap. In that case, is it actually better to use a star ground on the PCB instead of a pour?

Thanks!!

OK, been on the forums a bit, but I haven't really figured out where to ask this, so I will ask here and hope I get some good answers 🙂

In a nutshell, I would like to learn how to become a good hands-on audio tech - with a view to testing, measuring and servicing audio equipment and ultimately possibly designing or modding my own stuff.

I have a basic knowledge of electronics and am not afraid of maths, but my technical 'skills' are pretty ****-poor right now. I suck at soldering. I don't have any test equipment or hardly any of the tools of the trade.

What I'd like to learn initially are two things - how to test and carry out basic repairs to audio amplifiers, and I would like to learn the theory of audio circuit design - amp circuits, filters, cross-overs, etc. I'd like to look inside an amp and be able to understand what I'm seeing there. What I'm hoping for is the Single Magic Textbook that explains everything in huge detail, all in one volume or set of volumes - and preferably in SI units! But, I'm open to other resources. I don't mind learning from hands-on experience but I can't afford to wreck stuff in the process!

So what do you guys recommend? Oh, a college/nightschool course is out of the question, though maybe a home-study/online-only course might be ok.

Now gone.... closed.

Free to good home is a Nuvotem Talema 0120P1-2-018 tranformer. I bought it in Sept 2019 and after rectification gives ±29VDC which is a bit high for an LM1875. I will cover postage in Australia.

230V primary, 18V 3.1A secondary x 2.

0120P1-2-018 | Nuvotem Talema 230V ac, 2 x 18V ac Toroidal Transformer, 120VA 2 Output | RS Components

When I put my test light to the negative side of this diode I get power and the amp works correctly. What is this issue? I checked the diode and it is good. Even replaced it so I assume it is another component.

Hi all.A very Happy New Year!

I know this topic has been discussed to death but has anyone definitive proof that stuffing or lining the insides of subwoofers both sealed and ported actually benefits?
If so,with what type of material and how.

TIA.

I am planning of building Troels " The Loudspeaker 2 " along the lines of Tobias's build
TheLoudspeaker_Tobias
but in 3 sections instead of 2 to facilitate ease of movement and simplify construction. 1. The upper section would contain the mid, horn and tweeter would be built along Tobias's line but width would be reduced to 55 cm as per " The Loudspeaker 2 " 2. The bass bin would be divided into 2 sections, roughly 55cm wide x 61cm high x 35.5 depth, one containing the BMS driver and vents, the other to be joined to provide the volume of a 180 to 190 litre box.My hope is for suggestions on the means of joining the 2 bins together in the most elegant fashion that would allow multiple times to be disassembled and reassembled while sealing the 2 halves together. My thoughts are 12 long bolts through the aft section, battens with barrel nuts against a brace on the fwd section but am open to other options. Material to be 1" and 3/4" Baltic Birch. Battens to be hardwood. Ease of construction to be a plus. Open also to the seal interface between the 2 units. I am mulling over several approaches.
Any Ideas?
Vanko

Hi,

Can anyone please advise on which Lundhal SE OPT to use for an EL84 project, possibly the RH84 amplifier - revision 2 should it be the 50ma 35H or 100ma 17H



The specs are -

Tube amplifier output transformer LL1663 5k : 8 ohms

The LL1663 is a four-sectioned dual coil C-core tube amplifier output transformer for 5 k: 8 ohms impedance ratio available in PP and SE versions.

The coil is wound using our high internal isolation technique with isolation foil between each copper layer. The core is an audio C-core of our own production.

Turns ratio 12+12 : 1 or (4+8)+(4+8) : 1

Weight: 1.35 kg
Static resistance of each primary: 102 Ohm
Static resistance of secondary: 0.4 Ohm
Isolation between windings / between windings and core: 4 kV / 2 kV
Max DC current through any primary winding: 160mA


(approx.)

LL1663/PP. Max primary signal 450V R.M.S. @ 30 Hz Max primary signal 40W (8 Ohm spkr)

LL1663/50mA Primary inductance 35H Max primary signal200V R.M.S. @ 30 Hz. Max primary signal. 8W (8 Ohm spkr)

LL1663/100mA Primary inductance. 17H. Max primary signal 200V R.M.S. @ 30 Hz. Max primary signal. 8W (8 Ohm spkr)

They are available here

Lundahl Tube amplifier output transformer, LL1663-100mA - Fidelity Components Shop

You can download the sheet here https://jacmusic.com/lundahl/datasheets/1663.pdf

I am in the UK so need 240v or 230v mains transformer
There is also a mains transformer here LL2758
LL2758 ⋆ Lundahl Transformers

Thanks for your help

Hi guys.

I have just purchased two SB acoustics 10" (SB29NRX75-6)drivers on ebay for a very good price.

I intend to use these in medium-large boxes for my sealed stand-mounters to stand on; a three way active system using MiniDSP 2x8's for cross-overs. Think of the Tarkus and the Troels Gravesen Jensen 1071 as my inspiration.

I will use these for 90% music, and play my TV/Movies throught them too. Therefore I want to get the best possible sound for music.

My DSP can perform any parametric equalising, and linkwitz transform that I like. My question is: Will the vented alignment or the Linkwitz Transform sound better for music?

I notice that in WinISD these drivers model best for sealed and vented in more or less the same sized enclosure for each. I quite like the idea of having a removable port that I can seal up to try either.

Do you have any suggestions or input?

Kind regards,

Jai Stanley

Hi Folks,


I'd like to make a passive summing mixer (basically the same as the one at DIYRE) however I'd like to add adjustable make-up gain. See here:


SB2 Passive Summing Mixer Kit – DIY Recording Equipment


I'm struggling to find a complete schematic of a suitable make-up gain stage. I have a couple of TL074s and was hoping I could use them. I'd prefer the output to be balanced stereo.


One of the things I'm not clear about is how the addition of the make-up stage affects the output impedence.


Cheers,


Chris

Hello, today I was playing music threw EL84 SE amp. I was curious about the vibration from the music, I touched the tubes by hand and they were vibrating pretty badly.
Do you think that this can have effect on the sound?
What would be the best treatment?
Anyway, I wish you luck in year 2021 🙂
Thanks everyone for your opinion. Best regards, Michal

What do you think about it?

Today I received chinese ADAU1452 board. When powered it with USB port of the laptop, I can see that the leds are blinking and board seems to be working. After few minutes I found out that the transistor marked as IC4 becomes burning hot! Is this happened to anyone? Is this normal?

Has anyone built the amp described by Giovanni Stochino in Linear Audio (150W with BEF error correction)? He was going to make PCBs available, but there isn't anything about them on his website (superLinear amplifier)

Hey all
My first post so please be patient.
My amp blew a Chanel some weeks ago and I’ve dived in with very little knowledge of electronics.
I have managed to get the channel back by replacing several resistors and both the pt’s and ot’s but it has an unpleasant distortion.
I’ve checked almost half the components and they check okay.
If your familiar with this amp any help would be greatly appreciated.
Schematics wise, it is very similar to the a1 with just a couple of component differences.
If this helps, on the pt’s (tr6 and tr8) the collectors show around .5v and 1.5v respectively?? The other channel has them at 2.5 and 4.5v respectively?
Cheers

Another unique mic design, the element is a 2.5" speaker from a small boombox I found.Like all my other mic designs it needs a good amount of EQing to make it sound good.
Imgur: The magic of the Internet

I buildt a 13e1se amp 7 years ago. IDH Pentode driver with unbypassed cathoderesistor, shunt feedback from plate of output tube. A simple schematic
drawing attached.
Also two pics of one monoblock after mocking up 4p1l .
I have altered the original amp several times. It was buildt with Lundahl opt First, got custom sowter irons after a year, and Monolith custom choke and Opt
A few years ago. The driver tube was first 12gn7a, It was replaced by e282f
Which resulted in lower thd. With the ll opt output at clipping was about 32w
As the Monolith opt has a higher reflected load output is just above 20 W
I intend to change psu and up the power at clipping.
So I did not have any second thoughts about abusing the top plate with some
Holes. The last years my main interest has been dht's.
So let's check the 4p1l as pentode driver.
The schematic shows the starting point. Suggestions for improvements are very welcome.
Ps : Ale I had forgot that pout was lower with the Monolith opt. The 4p1l is not resulting in preliminary clipping

Hello all, I have had this recurring thought or question when trying to determine how to model a speaker in a traditional open-back guitar cabinet. While not acting as a vented or sealed enclosure, I feel it is easiest to think of in terms of baffle step for a tweeter, with the baffle supporting frequencies that are small enough to reflect off the baffle. An open back cabinet would do the same, yet maybe extend the frequency response even lower due to the front and rear waves being unable to interact with each other until much lower.

Has anyone else had any thoughts on this or know of any literature on this topic? I seem to be stuck between two hobbies here( diy audio and a gear hoarder who masquerades as a musician)

Thanks

Hello, i have a Accuphase p300 amp, the main relay keeps shutting off after a couple of hours, after taking it to 2 techs who couldn't fix it I tried adj the Bias and the Dc offsets, and so far it seems to have fixed the problem, can someone tell me what the values should be and where and how to measure. Thx.

I’m on a DIY mission to build a 200w mono guitar power amp, and stubbled across a PCB I like that I also want to make changes to. What I want to do is change the tubes from EL34s to KT88s, but am unsure of how to accomplish this. What will I need to change on the PCB, if anything? Will it just need to be rebiased, or will I have to add or take away different components from the PCB, and its power supply? I’m pretty new to this stuff if you haven’t noticed and am also having a tech help me build it so I won’t die.

Just traced the circuit of Mark Levinson Power Supply PLS-226. May be useful for anyone need to do some repairing of Diy a clone.

Hope it helps

I've dabbled in tube amps off and on over the past 20 years or so - nothing over about 30 watts, and nothing left permanently assembled. Typically I build solid state, up to the kW range. About a year ago, I had this hairbrained idea to get some Tubelab kind of power. It was originally supposed to be a bass amp, but I think it will eventually become a couple of monoblocks. So far its just the one prototype, but I'm quite pleased with how it sounds. I was running 'full music' the other day, scaring the heck out of the dogs. Next will be some full power testing with a dummy load = to see if I want the next size power transformers or if I cross the magic 200 watt threshold with the ones that are in there.

It did have its share of problems, but nothing that couldn't eventually be fixed (snivets, and a total revamp of the bias board). There will be some tweaking while I'm digging up parts for a 2nd channel. I'm sure I can come up with a better layout which might let me shove the open loop pole up a little bit, and there will be some protection circuitry added besides fuses and the delay for the HT.

Hi all and happy new year,
i'm a newbie and i'd like to understand what happens if i match vb with vas having a qts of 0.31 in a vented box?

the reason i'm asking is to match fb to fs and f3

And if i make a box too big can i correct the port vent to tune the box to avoid boomy bass'?


Scan-Speak 21W8555-10

FS 20 Hz
QTS 0.31
VAS 134 L
SD 220 cm²
XMAX ± 6.5 mm
Electrical Q QES 0.33
Mechanical Q QMS 4.50
Total Q factor QTS 0.31
Suspension equivalent air volume VAS 134 litres
DC resistance RE 5.5 Ω

thanks in advance for any suggestion

I need 2 .5mh air core inductors . I would prefer 14 gage wire. Shipped to 30290 in the USA .

I'm seriously considering cloning the Unity half of a Yorkville U15. This is for outdoor PA use, not home hifi.

For those who don't know, a U15 uses a 15" driver for the low end, and a 15" conical multiple entry horn for the mids and highs. The horn uses 3 mids (5") and 1 compression driver. Yorkville dealers will sell the horn, mids and compression driver by themselves. Cost will be about $700 for the pair.

I have the following questions:

1. Does anyone have a schematic for the crossover circuit? GOT IT!
2. Does anyone know the crossover frequencies and slopes? GOT IT!
3. The U15P has a digital crossover/dsp. Any info on its crossover points, slopes, and notch filters? GOT IT!
4. Is there a compression driver cheaper than the specified BMS 4550 that would be suitable? They're ~$170 (each), so it's about half of the cost for this project. I'll be using DSP so it doesn't have to be a perfect match for the BMS 4550.
5. Has anyone done this project? It seems like the easiest way to get a pair of multiple entry horns going on a budget.