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I started a Columbus Audio Society. We have meetups every Friday. Comment if you want to join

I run two audio technician groups on Facebook. One for casual posting and one for technical discussion. To be added, comment your Facebook usernames and post a pic of your workbenches. Each group has 100 very talented members

Has anyone here done a comparison of the Yamaha M70 to other power amps?

Needs to be no more than 100mm tall (originals are 94mm) with lead spacing of 28.5mm and screw terminal and 20-25mF with at least 100VDC. Already checked Mouser Digikey and Newark and RS components. Any luck from anyone? Hell, I'll even take solder tab mounting style. The original Philips caps...

preamp output signal is clean, power amp output signal is clean when the jumpers are removed and i run the signal generator straight in to main in. the signal only gets bad when the jumpers are installed and the balance knob is off center. i probed the balance pot and the signal looks fine...

i pulled all the TRs out of circuit and they all test fine. the resistors test fine in circuit. where should i go next?

The relays for this amp need to be replaced. Where can I find replacements? Seems they need to be screwed in to the chassis and I can't find relays like that...

I need to replace this relay... can someone help me find a replacement?

I have replaced every electrolytic 4.7µF and below with polyester film by Wima, all other electrolytics with Nichicon FG when in signal path (and Nichicon KL for the 10µF in the switch circuit board and control board) and PW and VR when in power supply and protection board. The big cans I...

Lots of these transistors (they are on my bad transistor list) in the input assembly, the switch circuit assembly, and the power amp assembly. Should I replace them all or just the ones in the power amp? I pulled a 2SA809 from the input board and there was no visible corrosion on the leads

Without a load, the amp has normal output. With a load, the positive half of the left channel waveform clips. All the voltages for all the transistors check out per the schematic. I swapped the lamps and the issue remains in the left channel. Using signal tracing I found the signal becomes...

So i have a bunch of different types of capacitors that i’ve ordered over the years. Nichicon KL, ES, PW, VR. Elna Silmic II and a dark blue panasonic that can be ordered from mouser. And finally a UCC cap from a Yamaha C2 i recapped. Well i tested each one for THD at 10khz and there was 0...

when load is removed, distortion leaves too. any clue on where to test?

I have a pair of B&O Penta speakers and was wondering what amp would sound better. The issue with the Parasound is that "Occasionally the sound fades".

I have the option to replace the Pioneer. I will be using Dynaudio Contour 1.1 speakers. Should I pull the trigger? Do you guys think this will be an upgrade at all? The Pioneer seems hard to repair and the Denon seems easy which is a big factor for me.

replaced the bias transistor and tested the driver transistors, they seem fine. gonna order new outputs and then try the dim bulb test. can’t find replacements for the 2SA1106/2SC2581 though...

I have deduced that the bias and output and driver transistors are not the source of the issue, neither is the preamp stage. i have checked each of the transistors for .6 Vbe and they all check out fine. where should i look next? the issue is not dependent on load. also, the output transistors...

I replaced the shorted 2SC1775 (TR311) with a KSC1845 and now the distortion is too high (.06% instead of the .006% I see on the other channel). What's the next move? All the electrolytics have been replaced.

Already pulled and checked the bias transistor and tested all the fuse and emitter resistors as well as the input voltages. Also replaced the bias pots. Where else should I test?

I am getting 120hz hum that increases when volume is turned up. when volume is at minimum, the hum is nonexistent. I have replaced the three main power supply filters, one capacitor in the preamp board and all the 2sc458 LGs with KSC1815 the hum persists and is louder on the right channel

I have a pair of B&O Penta speakers that need a preamp. I bought an HK825, HK Citation 21, and Luxman C383. The HK825 measures the best on my THD meter but would be the worst out of all of them if price was the only indicator of performance... also kinda want to recap the HK825 with Elna Silmic...

I can't find a replacement standby transformer, having no knowledge of the voltages (schematic just calls it "ac low" and 12V) so I was planning on just converting this amp to a power amp. First step was to put a jumper in place of the also broken relay so I could turn the amp on. It idles like...

Going to recap both of my Yamaha M60s... They may be the last amps I put in my stereo for a long while. I'm using Nichicon PWs throughout. Any point in using FGs? The amp appears to be direct coupled throughout...

Anyone have any experience with the sound of each capacitor? I already use Nichicon PW for everything that isn't coupling related. I've also seen posts where people say to use Elna Silmic IIs for Marantz and Sansui...

I bought 100 of these to use in place of mica and thermal paste and I wonder if the thermal conductivity is good enough. https://www.mouser.com/ProductDetail/Bergquist-Company/7403-09FR-85?qs=l%252BBQA801HCJYs1xFKBiS4A%3D%3D