Delay function

[SpareRibs]

Hello,
Is there some type of delay I could build to put in front of my SS amps to make the sound less brittle ? I guess I want to simulate tube sag.
I have a 15 watt Squier, and an unknown branded RMS, and a Crate G40 C.
The Crate has chorus and reverb which has the effect of, thickening and warming the sound.

[Mark Hammer]

You appear to be mixing up a few different things. Simulating "tube sag" is unlikely to be achieved via delay. Looking at the schematic for the G40C, there appear to be a few places where you might be able to mod it to be a little less bright...assuming that's what you mean by "brittle".

It would appear possible to change the location and type of clipping diodes to get a more compressed sound, similar to a Tube Screamer pedal, but that would apply only to the dirty channel. If you want tube-like sag in your clean channel, I think you're barking up the wrong tree.

Another thing you might consider is purchase of a compressor pedal. Most people tend to misuse them, though.

[Enzo]

In guitar amps, we use "delay" to mean echo, not some sort of pause.

I agree with Mark that a compressor will or at least can yield the envelope you seem to desire.

[Steve A.]

I'd suggest trying a low gain overdrive pedal like a Sparkle Drive with its control to blend in the clean signal.
I never liked the squishiness of a compressor right after my guitar until I got a Barber Tone Press earlier this year with a Blend control to mix in the clean signal. Wampler makes an Ego compressor with a similar feature plus tone controls...

Steve A.

[tedmich]

I've never failed to be underwhelmed by what compressors do, but its probably worth a try if you desire something subtle.

[Enzo]

For better or worse, he thinks he wants sag, so other than a compressor, how could we introduce sag from the outside?

[Mark Hammer]

"Sag" is frequently associated with dying carbon-zinc batteries...at least when it comes to fuzz pedals. Personally, I don't think anyone has really come up with an analog circuit that correctly emulates the dynamic changes in current capability that a barely-standing carbon-zinc 9V battery has. Providing a variable voltage output on a power brick, so that one can feed a pedal a robust and stable 7.8V is not an emulation of a dying battery in my view.

But that's a tangent.

Some of the natural compression that older tube amps have comes from the use of a tube rectifier. If you've ever pulled the 5Y3 or 5AR4 from your old amp, and subbed a solid-state module, you will notice a little more stoutness and "bark" from the amp.

What I never hear discussed, however, is the possibility of changing a 4-diode rectifier circuit in a solid-state amp with some sort of tube rectification.

Or could that even happen?

[Enzo]

Well, sure it COULD. Need a transformer for the heater, 5v for direct heat or a 6v otherwise.

But a series resistor simulates that reasonably. We've added sag resistors to tube amps with SS rectifiers.

That is what I think of when they say sag. Maybe I am limited, but I have never heard sag applied to a pedal.

[Steve A.]

For better or worse, he thinks he wants sag, so other than a compressor, how could we introduce sag from the outside?

I interpretted his post as basically a request to make the clean channel of his SS amp sound more like a tube amp with him suggesting that adding tube sag might help (a suggestion I disagree with.)

I've always associated "tube sag" with a cranked output section, especially when a tube rectifier is used. As for the compression in preamp tubes I attribute that to "tubeosity"...

Steve A.

[Enzo]

In my mind, the B+ sags when sudden current draw occurs. The drop across a tube rectifier is a major source of that yes. That causes compression as when B+ drops the gain of the power amp drops, then as the voltage recovers, so does the gain, causing some sustain that would not otherwise be there. The gain is ramping back up as the note fades down.

I never associated it with preamp tubes.

[Steve A.]

Enzo, I was referring to compression in preamp tubes not tube sag. I've hardly ever been allowed to turn up my tube amps enough to get tube sag so it is not something I think about much...

Steve A.

[Enzo]

Well I think we are not batting a word ball back and forth. I think you and I are talking with different things in our minds.

The OP went with sag, so I accepted that as the premise. Sag to me is the B+ thing, and it of course is more apparent the louder we get, but it is tied to dynamics. Compression being the reduction of dynamic range, which in my mind is the result of power supply sag. Certainly other things can cause compression too.

[Steve A.]

Agreed. The OP did say "I guess I want to simulate tube sag" but I think that he guessed wrong...

Changing the subject rather abruptly do you have any suggestions for an adjustable bias circuit for a Peavey Classic 30 or 50 amp? Here is the thread...

http://music-electronics-forum.com/t41573/

Steve A.

[robthequiet]

After reading the thread I think I'm not sure how to approach this without asking what you mean by tube sag. But if you want something that resembles a tube amp that sounds pretty clean if you play softly but starts to sound a bit sparkly when you hit the strings harder and get some levelling of the volume, I would go with a Tube Screamer type of thing. It would have a tone control to round out the tone while giving you some gain. I agree with other posters that a compressor may not get a good sound, in fact may get the opposite of warmth depending on how you like to play. If you like the way the chorus and reverb warm up the sound, the older (vintage type) chorus, flangers and delays tend to cut out a lot of highs, so maybe get an old Boss chorus (if it says "Analog Chorus", best bet) and give that a try. Hope this helps. If it's something you want to build yourself, go with the Screamer first. Maybe buy the analog chorus and build the screamer, depending on getting the right parts.

[SpareRibs]

Hello,
Well then all that being said, is there anything else I can do to the circuit inside the amp to warm it up more ? I have offset the clipping diodes, and added a 12" speaker which helped tremendously. It is a Fender Squier 15.