Hi All,
I've heard metion of a singal internal control that adds or subtracts high-end in the overdrive channel. Does anyone have a layout or diagram they could post.........Haveing a hard time figureing where it would go.
On a side note.........I realy like this new forum!!! Lot's of helpful info.....I wish it was here when I started my first dumble style amp a few years back!!!
The amp that needs alittle more high end is the Hybrid a1? It's posted here in the hybrid heading of the files section with just a bright,deep,rock-jazz swithches..........if that helps, Does the high end control come in on od1 or od2? Any help with this would be great!!!
Thanks again!!!
Chris G
Chris G wrote:Hi All,
I've heard metion of a singal internal control that adds or subtracts high-end in the overdrive channel. Does anyone have a layout or diagram they could post.........Haveing a hard time figureing where it would go.
Maybe you're refering to the post OD tone stack? Commonly called the Hot Rubber Monkey or HRM. Take a look on the files page for the 97 schematic. This tone stack is built using trim pots.
I use a control as described above by Dogears, but place it just after the OD input trim control before the grid resistor; used to reduce highs going into the OD section (pre-OD).
D
I question whether that is better.... If you cut the highs before, you lose the harmonic content IMO. I feel it is better to shape it after. In a well laid out circuit, the results would be better, once again IMO.
Other than some questionable 30 year old network, I only know of Dumbles that use the standard preOD network, or the HRM lowgain network which has a high end preemphasis! The HRM design adds the high stuff to be filtered later.
Try the post OD filter IMO.
dobbhill wrote:I use a control as described above by Dogears, but place it just after the OD input trim control before the grid resistor; used to reduce highs going into the OD section (pre-OD).
D
I agree: it does reduce the amount of harmonics, but I liked it better when I tried it before and after the OD section. I didn't use the whole HRM tone stack, just a simple high frequency roll-off type control. The main reason I put it in was to negate the effects of the brite switch. I think it would be a worthwhile experiment to install both and toss what doesn't work. I'll post results if/when I try it.
Thanks, D
Chris G wrote:The amp that needs al little more high end is the Hybrid a1? It's posted here in the hybrid heading of the files section with just a bright,deep,rock-jazz swithches..........if that helps, Does the high end control come in on od1 or od2? Any help with this would be great!!!
Thanks again!!!
Chris G
Chris, looks like everyone missed the real point. You need MORE top end not less.
Questions Questions
1. How is the clean tone? Enough top end?
2. What size suppresor (snubber) caps do you have on the OD tube?
3. How much shielded cable? Even a little is a lot on these amps.
Ideas to brighten things a bit.
1. Use lower suppressors, but I would not go much below 250pf. Otherwise the "skritch factor" might become annoying.
2. Try a small pf cap on the OD Output control. maybe 5 to 15pf.
3 Add a cap in parallel with your input series resistor above the trimmer control. Maybe 5 to 40pf.
4. If your amp has a common master a 25 to 47pf bright cap on the master really livens the sound.
Just be 2 cents...
Gary
Located in the St Croix River Valley- Afton, MN
About 5 miles south of I-94
aka K0GWA, K0 Glas Werks Amplification www.glaswerks.com
Chris G wrote:The amp that needs al little more high end is the Hybrid a1? It's posted here in the hybrid heading of the files section with just a bright,deep,rock-jazz swithches..........if that helps, Does the high end control come in on od1 or od2? Any help with this would be great!!!
Thanks again!!!
Chris G
Chris, looks like everyone missed the real point. You need MORE top end not less.
Questions Questions
1. How is the clean tone? Enough top end?
2. What size suppresor (snubber) caps do you have on the OD tube?
3. How much shielded cable? Even a little is a lot on these amps.
Ideas to brighten things a bit.
1. Use lower suppressors, but I would not go much below 250pf. Otherwise the "skritch factor" might become annoying.
2. Try a small pf cap on the OD Output control. maybe 5 to 15pf.
3 Add a cap in parallel with your input series resistor above the trimmer control. Maybe 5 to 40pf.
4. If your amp has a common master a 25 to 47pf bright cap on the master really livens the sound.
Just be 2 cents...
Gary
Hi Gary,
You are correct!!! The amp is kinda muddy sounding....I have to run the treble and presence controls up very high to get the amp to brighten up.
to answer your questions:
no, the clean dosen't have enough highs either
I have 300pf ceramic disc caps for snubbers
I have a lot of sheilded cable...........just a ton!!!!
I couldn't find 2 250pf caps for the snubbers........I'll look for some!!!
I will try a small cap on the od level control
I removed the bright cap on the overall master......I'll try a smaller value instead.
Thank-you for the info Gary......I will add some pics asap!!!
Are you running the erroneous 330k resistor that is after OD2? It should be 150k. That will really really help. 330k is plain wrong.
Hi Dogears,
Thank-you for the response!!!!! I have the 150k's in place. my amp is the hybrid a1 schematic in the file section with a few twists.
1 I used the old power supply layout and values( with the radial caps in series)
2 I have a complete set of twin trannies....power output and choke....The latter has been changed to a 10k resitor
3 the twin output tranny is 4ohms only........I only have 16 and 8 ohm cabs
4 I added a effects loop,1/2 a 12ax7......with a single return control,b+ is tapped off the 3rd stage.
Thanks again D.E.
Chris G
Chris G wrote:2 I have a complete set of twin trannies....power output and choke....The latter has been changed to a 10k resitor
10K resistor instead of a choke? Wow, that's some serious voltage drop! Most folks use a 500ohm to 1Kohm resistor here, 10W and up. Did you try any other values?
Ditto.... I notice mucho highend loss if I go over 500ohm. Try 250-330ohm with the 100 watt amp.
mlp-mx6 wrote:
Chris G wrote:2 I have a complete set of twin trannies....power output and choke....The latter has been changed to a 10k resitor
10K resistor instead of a choke? Wow, that's some serious voltage drop! Most folks use a 500ohm to 1Kohm resistor here, 10W and up. Did you try any other values?
Hi Guy's
I will have to check the resistor I have in there I may have confused the wattage rateing for the actual value.Maybe I can post a picture or two as well.Here's one of the outside.Thank-you for the info!!!
Chris G
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Since I'm on abit of a roll here how bout a shot of my first dumble clone!!! This amp has sky,hrm,mid boost ,and preamp boost on the footswitch.
Thanks
Chris
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