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Broskie Four Way Series-Shunt Crossovers and resistance values.

June 1, 2020, 11:17 am
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Re Broskie Four Way Series-Shunt Crossovers and resistance values.

This is an interesting article with a revised series network topology.

New Crossover Designs


All values in the article are all for 8 ohm values of R but what if you are using drivers with a different values of R?

Assume a 4 way design using a 4 ohm bass / 4 ohm upper bass / 4 ohm upper mids but an 8 ohm tweeter.

Am I right to assume that in theory the component value for the treble C1 will remain as calculated, but that all other component values will obviously change due to the 4 ohm R values?

Usually if impedance R halves then inductor values halve and capacitor values double. Is this the case here?

The only one that would not change would be the 8 ohm tweeter C1 which would still be a 5.6uF capacitor.

Math here

C1 = 159155/R/F3

C2 = 159155/R/F2

C3 = 159155/R/F1

L1 = 1k*R/(2*pi*F3)

L2 = 1k*R/(2*pi*F2)

L3 = 1k*R/(2*pi*F1)

Much fun

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Streaming from SSD

June 1, 2020, 11:33 am
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This is basically a question about SSD bandwidth as it relates to music streaming while performing other tasks:

I'm preparing to build a PC that will include at least one Corsair Force MP600 M.2 SSD mounted on a X570 motherboard (very fast). If I use one SSD that is partitioned for system, data and my FLAC music files, will I be able to stream music uninterrupted while the PC is also accessing system and data files? Or should I get two SSDs and dedicate one to music, read-only?

The additional cost of a second SSD would not be all that great, but I'd like to know it would actually be useful.
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Voltage dependent load?

June 1, 2020, 12:00 pm
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Is it possible to build a load that mirror it's load to an input and multiply by 10?
Lets say I send 1V into the "sense" part of the circuit and that make the load, load 10V or by switching, 10A from a secondary power supply?
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Any SM Pro Audio V-Machine owner here?

June 1, 2020, 12:03 pm
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Hi all,

I purchased this stand-alone VSTi player some time ago. It worked great, apart from the fan noise, for which I already found a solution.

However, during the modification, I accidentally cut some PCB track. Now I need some help from another owner who could take a close-up photo of the damaged part. I would like to restore the track.

Any help warmly welcome. I understand a lot of units have been sold in Australia. (I suppose there isn't any chance to obtain the schematics, and SM Pro is out of business)
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Testing a Leslie Rotary Speaker w/o the controller

June 1, 2020, 12:08 pm
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Any idea how I might be able to test, or demonstrate the condition of, a Leslie rotating speaker cabinet without the organ/controller?
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Testing a Leslie Rotary Speaker w/o the controller

June 1, 2020, 12:08 pm
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Any idea how I might be able to test, or demonstrate the condition of, a Leslie rotating speaker cabinet without the organ/controller?
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Center Channel Stereo Tube Amp

June 1, 2020, 1:57 pm
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I have seen that some stereo amplifiers from the 60s have a central channel, such as the Fisher X101D, or the Scott LK79, among others.
I know it is a connection between the 2 secondaries of the output transformers to run a third speaker called the center channel, I have seen the circuits and understand it, but I would need someone to technically explain how it works.
Thank you so much
Gusmore
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Looking for good class AB amp

June 1, 2020, 2:06 pm
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Hi all,

I’m looking for a really good class AB amp that could fit in 2U chassis.
I’m a beginner but I want try to build an high quality amp (2*100/150watt on 8 ohm)
I would build the honey badger but I think is too big for a 2U enclosure.
My idea is to use the side heatskink of the chassis (for example the dissipante of hifi2000)

I found on AliExpress the L12-2. Seams To be be a good amp but ... I don’t know.
I need as well a guide to build it and which checks I have to do before the first switch on (it’s my first amp)

Could you help me to do the right choice?

Thanks
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Scott 200b no stereo

June 1, 2020, 2:40 pm
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First post here, I am learning from you guys as I am a total newbie seeking help here. I have a Scott 200b that has good tested tubes but I can hardly hear the right channel. Plugging my CD player into the Tuner inputs I can only get anything out of the right if the left is plugged in and it is not stereo only mono. The right preamp adjustments, bass and treble don't work in any case at all. As soon as I unplug the left rca it's almost silent unless I turn it up to 10. Plug it back in and the right comes back on at a reasonable volume. I cleaned the selector switch with Deox it. Any suggestions would be appreciated. I also wanted to add that the bias adjustments don't work either.


Thanks
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Behringer DDM4000 Issue and Repair Ideas

June 1, 2020, 2:42 pm
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I recently got a used behringer DDM 4000 DJ performance mixer and while testing I found that the channel 1 inputs (both phono and line) seem to only allow left signal to get through.

There is a small amount of signal in the right channel, but I'm not sure if it's bleeding through.

Is this something that I should be attempting to repair myself? What might a likely component that failed be? Capacitor? I'm pretty good with the multimeter and soldering iron.

Thanks agin.
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Dual sinewaves?

June 1, 2020, 3:08 pm
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I am messauring a 1khz signal trough a phonostage i bought on ebay.
But how come I get dual sine waves,I only use one channel on the scope.
Anyone...

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Attached Images
File Type: jpg Dual sine waves.jpg (207.5 KB)
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Value of mullard trophical fish caps

June 1, 2020, 3:27 pm
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Acoustic centres of midbass horns Q

June 1, 2020, 3:58 pm
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I've done some googling a long time ago and ended up with conflicting answers...

On a midbass horn I'm looking at having the smallest ctc spacing to the midrange horn. Does offsetting the midbass driver to the top of the cab move it's acoustic centre upwards ?

My intuition says no but hopefully I'm wrong ?


Dodgy pic to show the difference, viewed from the side..

Attached Images
File Type: jpg hornQ.jpg (33.9 KB)
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Thoughts on the Dynavox LY302F?

June 1, 2020, 4:31 pm
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Help me understand car specific audio drivers

June 1, 2020, 4:48 pm
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Sorry I know this has probably been debated several times, I just had some specific questions.

1. I've heard many times that value wise, raw diy drivers such as the ones off of parts express are far better in value than car audio specific drivers when it comes to audio quality. I'm planning to upgrade the sound system in my car, and I'm looking for 6.5" component speakers to replace the stock ones. I've heard Morel makes decent component car speakers so I was considering the Maximo 6s: Morel Maximo 6 Maximo Series 6-1/2" component speaker system at Crutchfield

Would something like a Dayton audio woofer such as: Dayton Audio RS150-4 6" Reference Woofer 4 Ohm and a matching tweeter be of much better value when it comes to sound quality?

I understand car audio specific speakers are more durable, but I don't drive a Jeep or anything so it's not like they are going to be exposed to the elements much. Is there any other reason people buy car audio specific drivers instead? What would you guys do?

2. I've been wondering the same thing about these car amplifiers. You can get chip amps like this one: Sure Electronics AA-AB34181 6x100W TDA7498 Class-D Amplifier Board

But for a "car specific" amplifier that's enclosed with the same output capacity and all you have to spend atleast three times the amount it seems. Why? I know the boards run on a higher voltage but you can just use a 12v to 36v step up to power it, right? So why are car specific amps so much more expensive?
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300B BIAS

June 1, 2020, 4:50 pm
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My bias as measured on my 300b goes wildly up and down. The negative voltage to the tube is steady. The B+ voltage is also changing wildly up and down. This is a mono block and the other works properly as wired. I am using DC heating and do not use a hum pot. The 10 ohm resistor is soldered directly on the leg of the 300b. Any ideas.
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Fluctuations in mains power...

June 1, 2020, 4:58 pm
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I never thought about fluctuations in the mains electrical lines affecting class a amplifiers. Our power in the Philippines is not stable to say the least. I measured a couple times a few months ago wondering about voltage for running 110 volt power tools. Where normal would be 220 volts, we had 180, 185, 200... Although I heard the power company did something with the nearby transformers, I haven’t tested recently.
What effects could these fluctuations have on an F5 for instance? Could it have any detrimental effects on the bias of the amp or damage the power supply?

Thanks for looking & have a nice day!
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Spendor 7/1 Mid-Woofer Replacement Help

June 1, 2020, 5:49 pm
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Hello all! I need your advice - assistance if you can.

I bought a set of SPENDOR 7/1 Speakers for a song - and am trying to gauge my options to replace the Mid-range/Bass speaker on both sides which are not functioning properly.

This model is probably the least popular I've ever seen in the Spendor line - so I don't want to invest a lot of money in repairing the existing mids - if they are even salvageable. The mid is a proprietary speaker from Spendor - and I suspect is will be cost prohibitive to buy replacement drivers. I have reached out to Spendor and they directed me to Bluebird Music - the US rep for Spendor - who are not very responsive.

While I know replacing the driver with a non-Spendor driver may change the classic Spendor sound - I'm OK with that.

I've owned SP-100's, BC-1's and am waiting for the right deal to come along to keep me happy for the next 10 years. I suspect it will be Harbeth, Spendor or Linn when the time comes. Until then - I just need something to keep my ears in shape.

I am a newbie - and can handle the plug and play of driver replacement - but I want to make sure I select the correct substitute.

The Spendor has a ScanSpeak soft dome tweeter. (model -2010/8513)
Sensitivity is 88 8 ohms

Mid/Bass is an 8" (200mm with 40mm voice coil) Freq Resp. 60hz-20Khz

What are the important specs I need to have to assure the replacement is a technical match?

Thank you in advance for your PATIENCE and Assistance!!!

Gerry Dunn
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NOS film caps to trade... a ton of different types

June 1, 2020, 6:50 pm
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Hi, I have an overabundance of film caps, the problem is they are all the same values! The vast majority are 0.22uF with some 0.15uF, 0.18uF, 0.2uF. We're talking thousands here. There are some classics here like mullard tropical fish, sprague orange drops, aerovox v161-456. They are mostly polyester. Wesco, Paktron, ITW, cornel dubilier, GE and Panasonic are a few of the brands.
I am building a couple gainclones and need a lot of 0.1uF and some good electrolytics like 22uF, 47uF, 100uF and some good input caps 1.0uF to 4.7uF
Here is a picture with a few of the different types I have. Anyone interested in trade, please hit me up. Thanks!

Attached Images
File Type: jpg 2020-06-01 18.34.23.jpg (1,018.2 KB)
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RPI zero streamer with USB DAC - likely to get dropouts?

June 1, 2020, 9:41 pm
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Hi,
I am in the process of putting together a Class D amp with Khadas Tone Board DAC. I will be powerin gthe DAC with separate 5v PSU with enough grunt to power a RPI. The purpose would be purely to play files from another computer on my network using an app on my phone.

I have read that prior to RPI 4, there was some issues with glitches in the audio signal and that this was due to the shared USB and ethernet data bus on earlier models.

I'm not sure how common the issue is in practice, but am wondering if the issue would also exist if the RPI is connected to the network via wifi. I am looking at the RPI Zero W due ot price and size provided it will do what I want. A new RPI 4 seems like overkill and is quite a lot more expensive so would only consider it if it is my only option to avoid glitches.

Also, does anyone know what sized micro SD card I would need for Volumio or similar?

Thanks,
Mark
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