Tube Amp Archive

Just PM'd it to you...

The part # for the zeners i used is BZV15-C30R. It is a 30 Volt/15 Watt device.Place 2 in series to drop 60 volts. I found mine in my junk box so i can't give supplier details sorry. I just did a quick google search and seems like they are still readily available. cheers paddy hmm...I can't even fi...

Hi there I built a 2xEL84 Liverpool,had the same problem with higher than needed voltage on the secondary.I needed to drop about 60 volts DC and did this by using a couple of zeners in series with the centre tap.This works fine,just be sure to use sturdy devices that will handle the heat(mine bolt ...

That schematic is pretty much right. In the PSK you don't actually build the filter section for the power tubes twice like you did. The filters and dropping resistors for the fixed B+ are different values but what you have there would work just fine I think. Then there's all the scaling circuitry. ...

Any feedback on the proposed schematic above? I have soldering iron in hand and am ready to do some damage...

Awesome - thanks!

I can't wait to fire this thing up when I'm done with it!!!

Can someone confirm that on the schematics for the Liverpool, the bright switch is a SPDT ON-OFF-ON:

[img:357:243]http://glasselevator.net/images/brite.jpg[/img]

Thanks!

Start at the rectifier diodes, it's 'normal' up to that point. Then you make two 'branches' from the rectified voltage..one is for the Variable B+ including all the filters for the power tube plates/screens (if that's all you're scaling). The second 'branch' is for a new Fixed B+ supply with it's o...

jaysg wrote:

Fischerman wrote:The PS pot that Kevin sells has a 2KV 'case' rating.

Slight tangent --- would you please tell us exactly what pot this is that Kevin ships? I would expect a JAN or RV4 marked Clarostat/PEC/A-B. If there are other sources, it would be helpful.

It's an RV4 PEC, AFAIK.

OK...so bear with me here. I understand that if you scale the entire amp, the power scaling regulator simply goes between the rectifier and the filter section. But, if you're only scaling the power section, for instance, how do you separate the filtering for the fixed B+ supplies from those that are...

Not because of any voltage on the power scaling pot...that pot is mounted to the chassis just like any other pot. The PS pot that Kevin sells has a 2KV 'case' rating. There might be oscillation issues but I really doubt it. Thanks, I'll try them next to each other for ease of control then, and relo...

So, when scaling the power and PI sections and using a pre-PI MV as "Drive Compensation", would it be correct to assume that one should keep the MV pot well away from the scale control b/c of the voltage going through there? It would be nice if these two controls were next to each other on the panel...

My bad, it's The Ultimate Tone (TUT) volume 5 that has the Standard schematic in it not vol. 3 I have that volume of the series and am using it as a reference for the build. Still trying to follow some of the notes in the Standard build though! If you scale the PI then you'll need a pre-PI MV...if ...

If you are going to install a PPIMV, then why add power scaling? From KOC: "As you make the output stage look smaller, if you do not reduce the drive signal from the splitter, then the output stage will distort more than when it looked large. The 'Drive Compensation' control is essentially a post-p...

Yeah, I've seen some of the 18Watt discussion of this topic. What I am hoping to hear is someone's firsthand experience in scaling a Liverpool (or clone), and suggestions. If I followed it correctly, the 18Watt crowd suggests scaling the whole amp, but I've heard from at least one person that this m...