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October 03, 2023, 06:46:12 PM

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#21
Amplifier Discussion / Re: Modding an Ampeg SS70
Last post by FleshOnGear - September 23, 2023, 05:47:05 PM
You cannot view this attachment.
[Edit: Ok, I figured out a way to get photos on here. I haven't had time to open up the amp again, but I'll try to get gut pics at some point.]

As far as whether or not this is a good platform, I think it's ok. The pcb has flimsy traces and it isn't silkscreened with part numbers, so you need to do detective work to find the part you intend to replace. The speaker it comes with, the Celestion G12K-85, is a bit bright in this amp. The shelved low pass I installed (the 68n in series with the 820 ohm resistor) worked well for the G12K-85, but made the amp too dark for other extension cabs. I had to change the 820 to a 1k5.

The are some big positives for this amp. The cabinet is sturdy. Even stock the clipping circuit is sufficiently tube-like in tone. And, these are relatively cheap on the used market. Just a few tweaks and I got a great, dynamic metal tone.
#22
The Newcomer's Forum / Re: saturated's all encompassi...
Last post by nosaj - September 23, 2023, 02:25:34 PM
I tried to post earlier. Do you want a working variac? If so PM for details.
nosaj
#23
Amplifier Discussion / Re: Modding an Ampeg SS70
Last post by Tassieviking - September 23, 2023, 01:07:46 PM
I could not see the schematic, so I will post the ones I have if someone is interested.
Photos would be very nice.You cannot view this attachment.You cannot view this attachment.You cannot view this attachment.   
#24
The Newcomer's Forum / Re: saturated's all encompassi...
Last post by Tassieviking - September 23, 2023, 12:46:47 PM
while I got you here I am really struggling with trying to understand how to be safe with oscilloscope grounding.
I was going to put a two prong adapter on the cord to unground it but maybe that is not a good idea.
[/quote]

It has been a long time since I used my scope, and my scope is a real CRO.
I usually use one ground clamp that I attach to the 0v rail, as long as the 0v rail is grounded.

All my probes have a removable ground wire so all I am left with is the probe itself, I leave one probe with the ground wire attached.
My old "cathode ray oscilloscope" is nothing like the modern units most people have today, turn it on, have a cupper, use it.
#25
The Newcomer's Forum / Re: MarkBass/Class D amplifier...
Last post by Tassieviking - September 23, 2023, 12:35:48 PM
What model are we talking about ?
I have only one Mark Bass service manual, the Little Mark 2.
#26
The Newcomer's Forum / Re: MarkBass/Class D amplifier...
Last post by g1 - September 23, 2023, 12:17:37 PM
You have to deal with SMPS to get anywhere with these kind of amps.
see attached

another one here:  https://docs.google.com/viewer?a=v&pid=sites&srcid=Y2Fyc3UuZWR1LnBofGpiaGFsaWJhc3xneDoyYjgyY2E5OTZmN2FjZWQ0
#27
The Newcomer's Forum / MarkBass/Class D amplifiers
Last post by GeezerB - September 23, 2023, 10:54:53 AM
Has anyone looked at or attempted repair on these types of amps? I bought one non working for parts for a song... but now I see the complexity of such a device .   It seems that they are stingy with schematics and all roads lead to approved repair shops. This one won't even power up... no power LED, no fan, no life at all.   Just learning about class D, fascinating stuff!
#28
The Newcomer's Forum / Re: saturated's all encompassi...
Last post by saturated - September 22, 2023, 11:22:00 PM
I was watching a video on my tv and took a pic of the screen

anybody recognize these guys  :P



You cannot view this attachment.
#29
Schematics and Layouts / Raven RG100 Combo Schematic Wa...
Last post by willpirkle - September 22, 2023, 03:20:40 PM
schematic wanted: Raven RG100 2x12 Combo

One just came into the shop. It's a super simple setup and easy pcb access, bad filter cap... But I am looking for a schematic to add to the collection, and to look for anything else for completeness. their website is long gone but apparently they were designed in LA, not far from QSC/Quilter if my SoCal memory serves correct. it's been a while...

Thanks - will
#30
Amplifier Discussion / Re: Modding an Ampeg SS70
Last post by joecool85 - September 22, 2023, 01:18:58 PM
This sounds like a great platform, but not something I'm very familiar with.  Care to share any pictures?  We'd love to see it!