OD trim voltage value

[Structo]

Sorry I'm not that good at reading load lines.
I was going by what was stated on the top graph.
Supply=334.

But I do see now your points on the graph around 200v.

Thanks

[bluesfendermanblues]

So you did (partly? mostly?) compensate for the resistance changes. The 220K stage break point is about the same, and the 150K stage is down by about 30%.
MPM

I don't know if I understand you right, but I decided on using the amp with straight 100k on V1 and V2. And compensated for the loss of low end (compared to 220k/150k) by upping the cathode caps to 22uf's on V1 and keeping 5uf on the v2's.

[Structo]

How did that work for you?

Have you tried the high plates on V2 and keep the 100K on V1?

[bluesfendermanblues]

How did that work for you?

Have you tried the high plates on V2 and keep the 100K on V1?

Yes, I've tried the combo low plates on V1 and high plates on V2, but I like the sound of straight 100k better.

So I ended up with a #124 type amp, except for at few strat related tweaks:

1) 20uf on V1 cathodes
2) V2b cap 10n instead of 5n
3) 47n mid cap

In fact, the only strat tweak is 3) the 47n mid cap. 1) + 2) are more or less compensating for the lack of low end with low plates

Another 'tweak' is playing with the voltage dropping string, so V1 gets 185 volts, which I think help soften up V1 on a 100K amp.

[heisthl]

When your going for the last 5% the values that someone else uses are just not going to work for you. There are too many differences, even between identical builds. One man's 5uf is an others 10uf etc. These changes take less time to implement than talking about them, you ears will validate your decision, better yet, let someone else play your amp so you can be objective. On the first couple of clones I changed things based on what others said worked for them, do this more than a couple of times and you realize your tastes may be different and even your language descriptors may be different. It's been said by many - build the baseline amp first and then make changes that suit your preferences. Take notes if needed so you can remember how your ears perceived the difference between increasing bass with a bypass cap as opposed to using a larger coupling cap. Face it, you can change and evaluate every significant part in the amp in an afternoon. Then you can move on to the next build

[bluesfendermanblues]

When your going for the last 5% the values that someone else uses are just not going to work for you. There are too many differences, even between identical builds. One man's 5uf is an others 10uf etc. These changes take less time to implement than talking about them, you ears will validate your decision, better yet, let someone else play your amp so you can be objective. On the first couple of clones I changed things based on what others said worked for them, do this more than a couple of times and you realize your tastes may be different and even your language descriptors may be different. It's been said by many - build the baseline amp first and then make changes that suit your preferences. Take notes if needed so you can remember how your ears perceived the difference between increasing bass with a bypass cap as opposed to using a larger coupling cap. Face it, you can change and evaluate every significant part in the amp in an afternoon. Then you can move on to the next build

You're probably right - even if it's fun to exchange receipe's

[heisthl]

Yes, I've tried the combo low plates on V1 and high plates on V2, but I like the sound of straight 100k better.

So I ended up with a #124 type amp, except for at few strat related tweaks:

1) 20uf on V1 cathodes
2) V2b cap 10n instead of 5n
3) 47n mid cap

In fact, the only strat tweak is 3) the 47n mid cap. 1) + 2) are more or less compensating for the lack of low end with low plates

Another 'tweak' is playing with the voltage dropping string, so V1 gets 185 volts, which I think help soften up V1 on a 100K amp.

If you have the mid boost on a relay, a fun option is to also switch your .047 mid cap with a .01 on the other set of relay contacts.
I used to be a fan of 185V on V1A (100k plate) but lately I like 200 - 210 for the nice leading edge "ping" of brightness.

[bluesfendermanblues]

Yes, I've tried the combo low plates on V1 and high plates on V2, but I like the sound of straight 100k better.

So I ended up with a #124 type amp, except for at few strat related tweaks:

1) 20uf on V1 cathodes
2) V2b cap 10n instead of 5n
3) 47n mid cap

In fact, the only strat tweak is 3) the 47n mid cap. 1) + 2) are more or less compensating for the lack of low end with low plates

Another 'tweak' is playing with the voltage dropping string, so V1 gets 185 volts, which I think help soften up V1 on a 100K amp.

If you have the mid boost on a relay, a fun option is to also switch your .047 mid cap with a .01 on the other set of relay contacts.

I do have the mid boost on a relay, with a pair of free contacts....would you use the 10n with the mid boost engaged, and 47n without mid boost??

I used to be a fan of 185V on V1A (100k plate) but lately I like 200 - 210 for the nice leading edge "ping" of brightness.

I need the smoothness of lower voltage, when using EVM12L in a Thiele cab - even with a beam blocker. It would get way to "pingee"

[heisthl]

I do have the mid boost on a relay, with a pair of free contacts....would you use the 10n with the mid boost engaged, and 47n without mid boost??

Yes in fact just wire it like the mid boost and use the .047 like the .002 and the .01 like the 390pf except feed the NC terminal. So what if the series makes it's a little lower ( to an actual value of .00825). Nice fat Strat lead tone.

[Guitarman18]

Does anyone worry about the grid load on V1a when trying to accommodate a strat? The mid cap is often mentioned by Strat users but I can't remember many references to grids.

Cheers, Paul.

[Structo]

Do you mean as far as the 22K grid stopper?

[Guitarman18]

Structo wrote:

Do you mean as far as the 22K grid stopper

Yes, sorry, I was specifically referring to the grid stopper.

[talbany]

The grid resistor on the preamp stages typically ranges from 0 to 68K, although very large values, such as 470K, are sometimes used in high-gain preamps to shape the frequency response and prevent "blocking" distortion in the preamp section under heavy overdrive conditions. The Miller capacitance of a typical 12AX7 is around 151pF, so the upper frequency response -3dB cutoff point of a stage using a 68K grid resistor is around 15.5kHz. (Lower the resistor higher the rolloff) The frequency response drops to around 2.2kHz if a 470k grid resistor is used. This "free" response rolloff can be used to tame the "buzziness" of high-gain preamp stages without having to add additional rolloff capacitors. Perhaps the most important grid resistor is the one that goes to the grid of the very first stage, right after the input jack. This resistor is the one that prevents oscillations and pickup of radio stations and other noise due to long or poorly-shielded cables. It is not usually a good idea to eliminate this resistor. Ideally, it should be soldered directly to the grid pins of the socket, with very short leads

From Aiken

If dat resista goes bad take it back as that should be covered all up unda neef da wawentee!!

Tony VVT

[angelodp]

Henry, on that thought about the



If you have the mid boost on a relay, a fun option is to also switch your .047 mid cap with a .01 on the other set of relay contacts.
I used to be a fan of 185V on V1A (100k plate) but lately I like 200 - 210 for the nice leading edge "ping" of brightness.

can i implement that here.

ange

[IMG509]http://i260.photobucket.com/albums/ii9/ ... DL-B-2.jpg[/img]

[talbany]

Sorry Double