Vht d-50h tweaks

[talbany]

3 Ways to control/alter bass response in an ODS
1. changing coupling caps
2.Changing pot values (OD entrance/
drive/Od Vol
3. Bypass caps
There are other things too like changing the value of the slope resistor, but I would start 1-3 first

B.T.W.. IMO. Without using certain parts the O.D in these amps can get pretty aggressive/gritty/buzzy sounding
Tony

[ijedouglas]

For a 183 circuit, you may want to increase the filter caps to tighten up the bass. I see in the pics on the first page that it has 4 100uf caps in series then paralleled for 100uf. I have been experimenting with different caps in the reservoir and they make a big difference. Try 2 x 330uf caps like the original

[talbany]

For a 183 circuit, you may want to increase the filter caps to tighten up the bass. I see in the pics on the first page that it has 4 100uf caps in series then paralleled for 100uf. I have been experimenting with different caps in the reservoir and they make a big difference. Try 2 x 330uf caps like the original

True!
Dumble did like a lot of low end

But I did notice that if I put a little more low-end into the preamp circuitry, it was much more tasteful and fun to play.

https://ampgarage.com/forum/viewtopic.php?f=4&t=22012
(183 has plenty of lows due to the help of a 250k+ (260k/272k) Drive and OD level pots). So in order to keep the amp tight he upped the filtering especially while in overdrive..IMO. I don't know what value drive and level pots the Vht has but that would be the 1st thing I would check and possibly tweak if the O.D was too Bass heavy.

Tony

[Guy77]

I have been playing around with the whole 220k resistor in OD entrance and 100k trimmer pot and have found that changing the value of the trimmer and the 220k resistor can help add or remove bass from the Overdrive
For example you could also use a 50k pot with a 270k resistor or a 25k pot with a 300 k resistor (multiple resistors to get value).
So many different sounds from tighter with less bass to fatter with more bass and everything in between. I have found that the best sounds happen when the resistor and trimmer stay close to 320k but to each their own. I haven't tried this with specifically a 183 model so may even want to go larger than 100k with your trimmer.


Cheers

Guy

[talbany]

I generally find that the low end stays tighter by adding lows later in the preamp.
I start at the OD Level and work back. then the Drive pot and then the trimmer last (Same with the bypass caps) This way you can still have plenty of low end without the bass going too soft at the same time keeping the O.D smooth without the flabby low end texture:
This is just my personal opinion.

Tony

[JKRamsey1991]

I have one of these incoming. For the price I dont think theres another option close.

My question is what is your guys opinions on the most bang for the buck mods for these amps? Swapping caps to 6PS? Resistors to Carbon or Metal FIlm? Making it value wise identical to the 183 schematic?

[ijedouglas]

I have one of these incoming. For the price I dont think theres another option close.

My question is what is your guys opinions on the most bang for the buck mods for these amps? Swapping caps to 6PS? Resistors to Carbon or Metal FIlm? Making it value wise identical to the 183 schematic?

I would start out changing those metal oxide resistors for some good carbon film or metal film. Concentrate on signal path and plate resistors. Take a listen and if you are moving in the direction you like, start replacing the coupling caps with 6PS.

[JKRamsey1991]

Got my amp today and spent a few hours with it. Only complaint I have thus far with the tone is there is a bit of sizzle on the top end I’m not a huge fan of. Going to grab a different cab and try later to make sure it isn’t the speakers. Still a solidly giggable amp as is.

[groovtubin]

Had a VHT D-50 in house w/guitar tech friend who wanted MORE as well, AL i did was tie feedback point to Last 4th stage cathode .. Gave it alot more GRIND, ( which he LOVED) but not that infamous growl....itsa very hifi solid state sound to my ears....not a big fan personally..Good luck man!

[JKRamsey1991]

After playing a few gigs with the D50 I decided I will do a few mods. Going to take the circuit back closer to a true 183. Take the snubber caps down to the correct value and up the treble capacitor to 390pF. Also going to change the capacitors in the phase inverter to correct value orange drops. I have some carbon film resistors I may swap in as well. Will see how adventurous I feel once I tear into it.

[JKRamsey1991]

Pulled it out last night. Dropped the snubbers down to 50pF and hated it, went back up to 300pF so a small drop from what was there but this way it still had the smoothness. Changed the phase inverter caps out to some 715 orange drops as well. Will admit its a bit of an annoying amp to work on. Yes they used eyelet boards but the wires are just sitting on the eyelet not stuck through it. Only the components themselves actually enter the eyelet. Some of the wires barely had the ends stripped enough to actually enter the eyelet. Admittedly a small annoyance but a bit of a QC issue if you ask me.

[Dansamp1]

Pulled it out last night. Dropped the snubbers down to 50pF and hated it, went back up to 300pF so a small drop from what was there but this way it still had the smoothness. Changed the phase inverter caps out to some 715 orange drops as well. Will admit its a bit of an annoying amp to work on. Yes they used eyelet boards but the wires are just sitting on the eyelet not stuck through it. Only the components themselves actually enter the eyelet. Some of the wires barely had the ends stripped enough to actually enter the eyelet. Admittedly a small annoyance but a bit of a QC issue if you ask me.

Did you notice any difference with the new caps ??

[JKRamsey1991]

When I dropped the snubbers down to 50pF the overdrive was way more gritty and aggressive, which to me went to far. I put in some 300pF and it seems to add a just a bit more edge to the overdrive, but still smooth. The phase inverter caps I replaced with .047 orange drops and I think it reduced the bass a smidge. The amp is still on the bass heavy side for me as I keep the bass pot turned almost off but its still a good sounding amp.

[ijedouglas]

The amp is still on the bass heavy side for me as I keep the bass pot turned almost off but its still a good sounding amp.

What does your bass pot measure? The original had 311K. Reducing the pot value will bring back the useable range of the pot.

[JKRamsey1991]

You know I didnt even think to look or measure it. Maybe if I get a wild hair and take it back apart ill check that.