S.I.R. 100W SuperLead Schematic pt. II

[herbvis]

Sounds good brm, Just need a srv2000 and yer there

[Unique]

I agree. BRMSlash has closely nailed the AFD tone AGAIN and has certain characters about the sound adjusted to what he personally wants it to be. His spec has not changed much in a while, but tiny things like the composition of components and voltages have. He and I bounce ideas back and forth all of the time but that doesn't mean he changes the spec nor that I expect him to. I would imagine he as well as Nigel, has experimented more than anyone in this topic and as much or more than I have, but different experiences and ideas add up. We try stuff, we keep, we eliminate. Rest assured the PPIMV is adding fizz and rolling off bass, etc and BRMSlash knew it.

I know you guys have experimented with everything and it's been briefly discussed. In fact, it's you guys who are keeping this thread alive. Some of things I mention are also for others who are reading because not much is talked about them and they are an important part of the overall sound.

About the PPIMV, my PPIMV doesn't really add much fizz at all. My sound doesn't change much when I crank the power up, other than what is normal between quieter volumes and louder volumes. This is the main reason why lower and higher frequencies are not as present when you have PPIMV set low. It has nothing to do with the PPIMV causing this, or rolling off lows, but rather how our ears respond to frequencies. It's called the "Fletcher Munson Curve." When you are listening to sounds a lower volumes, the mid range frequencies are more prominent while the lows and highs will seem to lack. As you turn your power up and the levels increase, low and high frequencies will rise and become more prominent. Rest assure, if you record your amp at a low volume, then turn it up loud when you play it back, these frequencies will be there, as well as a higher noise floor.

However, I'm sure in some cases, depending on the components you used for your PPIMV, it could be adding some fizz. I think the tubes your using has a lot to say about this as well. Some tubes are just more fizzy sounding than others, especially at lower volumes where it's more noticeable.

To expand on this, since most here likely use the LarMar PPIMV, I will refer to that one. It diminishes NFB which affects a few things like effectiveness of the presence control and general response of the PI. The PI output load and time constant / frequency changes when using this PPIMV. As you turn down the PPIMV, there is more resistance between the PI output and power tube grids. These things certainly affect the bass and presence outside of the Fletcher Munson Curve effect. It will make certain amps sound as if they have more gain than without that PPIMV.

Keep in mind that I have used these in amps with no NFB or presence control as well as with cathode bias on the output tubes and that can give more of an idea of how things besides the NFB and presence control react to a PPIMV.

Take a dual gang pot and use it to ONLY adjust the PI load resistors from 220k, gradually down to 68k and you will hear how anemic an amp will get simply by adjusting those two resistor values. That is part of what this PPIMV does. Even going from 220k to 180k is audible in that the bass and drive diminish. As many of us have experienced, the LarMar is pretty good from 4 to 8 on the dial. Below that, it gets gradually more buzzy but is still cool for friendly volume levels.

I think I might have misunderstood what you were saying Coffee. Your right, one thing is for sure, my presence control is pretty much useless with the PPIMV, but I always have it set on 0 anyway so I never give it much thought. Thanks for sharing that info about the PPIMV that's interesting to know.

[BRMSlash]

Sounds good brm, Just need a srv2000 and yer there

Yeah, the reverb makes quite a difference in fine tuning the sound. I'm just using the Scarlett Plug-In Suite Reverb that came with my Focusrite 2i2 interface. It took me quite a while to closely mimic the reverb on the album. Any slight variations in the settings can make it sound off. An SRV-2000 would be great.

[pauldavidson1991]

I have a question about the shield trick?

I read through some of the old posts in the forum

And people seem to have done the shield trick at diffrent stages

Which is the most accepted gain stage to put it?

Cheers

Paul

[CoffeeTones]

Stage 1. Make it as safe as possible and use a grounded power cable. Use at your own risk.

[pauldavidson1991]

Thanks sounds great

One more question

I've built my amp to the Duke amp specs

Has anyone made the Levi specs version

And which one do you think is closer to the album?

[CoffeeTones]

Post links to the specs, so we know the exact ones you are using. Someone will answer.

[BRMSlash]

So I decided to get myself an SRV-2000. I've hooked it up & had a bit of a play yesterday. Sounds great, but I'm having a hard time using it with my interface (Focusrite 2i2, 1st gen). Only having 2 input & 2 outputs is tricky as the output is used to send my pre-recorded dry signal to the SRV-2000. The SRV-2000 then outputs back into the two inputs of the 2i2. I can monitor via the headphone output of the 2i2, but it doesn't accurately reflect the final recorded tone. I've tried the various switches and routing options, with limited success. It's hard trying to tweak the tone when I can't get accurate live feedback.

I think I'll need to get an interface with more outputs if I want proper stereo reverb. I guess the other option is just use it in mono.

[herbvis]

You can use it in your amps fx loop. I do it with mine. User setting 10 and 11 are good

[snakepit86]

https://soundcloud.com/shenierhandmadet ... -lynchback

Tell me what you think

This is the amp i build from scratch with the #36. Im using the Lynchback with a offaxis SM57 and my LP. The reverb is from the Lexicon Plate plugin (really awesome plugin, you will need no other!)

cheers

[CoffeeTones]

IMO, it sounds thin and strident. The basic AFD tone is there.

[blacklabel]

Hi guys, I'd like you to hear something about my jcm800 2203 (1982y) with #34. 6550 svetlana and china preamps tubes.
i uploaded some clips on soundclick, these are my first recording tests and i had no background music
i don't remember settings.. probably for all clips expect soma city, i had volume 8, presence/treble 0 to 2, bass 7, middle 5, gain low.
recorded with sm57 and V30

https://www.soundclick.com/bands3/defau ... id=1447256

[pauldavidson1991]

This is the one I meant

Sorry for taking so long to get back

[pauldavidson1991]

ok it never attached

Here is a link to it

https://www.google.com/search?q=levi+sp ... PJdjgD6IaM:

[CoffeeTones]

Can't see it. Pintrest is annoying. Let me know if these links are good.

Basic AFD spec

https://scontent-atl3-1.xx.fbcdn.net/v/ ... e=5D43A957

DukeAmps AFD shared spec

https://scontent-atl3-1.xx.fbcdn.net/v/ ... e=5D3DB8C2