The Amp Garage

I like measurements. They help me quantify what I experience. I wish I had that spectrum analyzer R.G. had, that function of my Rigol scope is limited. I agree anything real can be measured. Maybe not with the gear and process available to all of us, but it can help identify and filter out the vari...

Damned double post. The reply went through but the screen didn’t change.

Well, I don’t doubt it’s hard to quantify what is going on with the components. I have yet to find someone prove to me that different resistors sound different. I’m not saying it’s not possible, I haven’t heard it. I have heard the difference between silver mica and ceramic caps and it’s quite disti...

Anyone can buy (or steal) the rights to a brand name, and start producing product with the branding and look of the original (in this case being produced by "Shin-ei, LLC" perhaps another purchased brand name, lol.) Call me cynical, but I propose that if they look really good it'd be hard to object...

Did you happen to compare your pre- and post-replacement bias voltages/cathode currents? I'd bet you altered the bias setting when you changed the caps. I checked out the bias today and it was much as muchness. I found the EL-34’s were conducting less and the 6L6’s were conducting more. So it’s a b...

What I was looking for was the blue to brown resistance, and the blue/white to brown/white resistance. Are you able to check the primary to secondary voltage ratios? eg if a measured low V AC is applied to the 4ohm secondary, what V AC is produced across blue to brown, and blue/white to brown/white...

Those Vishay are noticeably upper midrange forward sounding , good for Marshall crunch , lots of harmonics . I really like that brand for the bias specifically. How did you determine that Charlie? I had issues with the highs in my Mesa Boogie SOB which I converted to a Mark 1. The fix was to get ri...

WhopperPlate wrote: ↑Mon Feb 12, 2024 6:08 pm

Mark wrote: ↑Mon Feb 12, 2024 3:15 pm Jupiter caps won’t like this. They have a good product.

I like their electrolytic caps . Time will tell how they survive .

I haven’t used the electro caps. I tried to get them from CE Distribution and they had run out of stock.
What do Jupiter electro’s bring to the circuit?

seveneves wrote: ↑Mon Feb 12, 2024 8:48 pm

Mark wrote: ↑Mon Feb 12, 2024 3:15 pm Jupiter caps won’t like this. They have a good product.

Well, sure. How could they? How many "Jupiter" branded caps do you see in vintage Fenders?

I know of a Bandmaster 6G7a that has some of them in it.

I replaced them with Vishay caps. Vishay bought up a lot of companies and makes components for many brands. I would have preferred Nichicon, but Vishay was all that I could get locally.
https://au.rs-online.com/web/p/aluminiu ... 45379?gb=s

Jupiter caps won’t like this. They have a good product.

A funny thing happened, I’m in the midst of repairing a Mesa Boogie 295 dual power amp. In another thread I talk about my findings and update the circuit diagram. https://ampgarage.com/forum/viewtopic.php?f=6&t=36878 I didn’t replace the filter caps as there is so many of them and I’m not experienci...

Here is a bit more information on the circuit diagram of the 295. It includes the presence control which is omitted.
Measurements will be forthcoming.

I fixed the blowing fuses, but I was getting bugger all out the amp. I checked the voltages on the plate and the first plate was 7vdc. I checked the plate resistors one was 22K and the other was 42K. I didn’t think that was the source of the fault. I lifted the coupling caps and the voltage returned...

I measured the resistance of the primary windings of the output transformer. The channel A transformer measured from blue/white to brown/white 87.2 ohm (EL-34’s class A). 108.6 ohms was measured from blue to brown. The channel B transformer measured from blue/white to brown/white 89.2 ohms. 111.1 oh...