Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: theundeadelvis on April 21, 2011, 03:22:40 pm

Title: 5G15 Reverb Too bright - How to tone down the tone?
Post by: theundeadelvis on April 21, 2011, 03:22:40 pm: Hello everyone! Hope all is well. I've been away for a while (new baby on the way=house remodel). I built a 5G15 reverb unit a while back, using the Weber layout, and I'm getting back to it for some final tweaking. I love it, but it seems too bright/treble-y. I end up never having the tone above 2 or 3. I'd like to get a more usable range out of the tone, but I'm not sure which components to work with. Can anyone please point me in the right direction? Thank you in advance!

Here's a link to the schematic: https://taweber.powweb.com/store/5g15_schem.jpg
And here's the layout I followed (will use Hoffman's in the future): https://taweber.powweb.com/store/5g15_layout.jpg
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: octal on April 21, 2011, 04:48:10 pm: I'm going to suggest the brute force method. You could add a treble shunt capacitor across R11. Try a .0022uf in parallel. Increase the value if it still has too much treble, decrease it if your wet sound is too dull.
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: theundeadelvis on April 23, 2011, 12:05:36 am: Thanks Octal. I will give your suggestion a try and report back.
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: theundeadelvis on April 23, 2011, 08:45:48 pm: Any suggestions for increasing the reverb mix? I would like to be able to get almost a 100% wet signal.
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: PRR on April 23, 2011, 09:06:03 pm: Make C8 1,000pFd.
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: alerich on April 24, 2011, 08:01:16 am: Quote from: theundeadelvis on April 23, 2011, 08:45:48 pm
Any suggestions for increasing the reverb mix? I would like to be able to get almost a 100% wet signal.

Would a larger value mix pot help in this regard?
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: sluckey on April 24, 2011, 09:12:46 am: This mixer will allow 100% wet or dry.
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: sluckey on April 24, 2011, 10:34:30 am: Although the above mixer will allow 100% wet or dry, I really don't think you'll like all wet. A very easy way to find out is just disconnect one end of C10 or C9 and you will have all wet. Then you could decide if you want to do the mod.
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: PRR on April 25, 2011, 06:22:56 pm: > This mixer will allow 100% wet or dry.

The dry side may have "trouble" shorting-out the cathode follower. 1% end resistance is 5K which won't drop the ~~1K CF's output by much; and if it does go lower it may distort as it gets weak.

That type pan-pot should have some source resistance. Since the wet side is ~~40K, and he generally wants less dry, 47K between CF and dry side of the pot seems like a trial value.

Agree that 100% sproing is probably not wanted. Reverb needs a "reference", and pure spring is nasty. Wet at 400% dry is pretty soppy, yet you still get the direct sound to establish what the reverb is doing and fill the spectrum space the reverb is missing.
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: octal on April 25, 2011, 10:59:47 pm: PRR-

I was thinking about your suggestion about increasing the value of C8- presumably to make the reverb bassier.

How would you go about approximating the corner frequency of the HPF created by C8? I'm having a hard time analyzing the circuit. The dry cathode follower output seems as if it would be essentially an AC ground for the wet signal, so my first guess was to add the output impedance of the recovery stage, the midpoint series resistance of the tone pot and the mix pot, but I think that's wrong. Could you enlighten me?

Nathan
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: theundeadelvis on May 03, 2011, 11:06:19 pm: Thanks guys! I love this forum! I wish I had more knowledge to contribute myself.
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: octal on May 05, 2011, 02:18:33 pm: Did you ever try any of these suggestions? If so, how did they work out?
Title: Re: 5G15 Reverb Too bright - How to tone down the tone?
Post by: theundeadelvis on May 05, 2011, 06:51:20 pm: I actually have not yet. With a baby on the way and a complete gut/remodel of the house, I keep thinking I'll have time, but haven't found it yet. As soon as I do, I'll report back.