jborders5 wrote:I'd mod it to a high plate using the #102 & #183 layouts before trying the HRM route.
So I've been reading a lot today and found a thread that said HAD liked symmetry in the valves, which was why his plate resistors were generally the same over V1 and V2. Now, as you know I do not want to mess with v1 but would that mean I can't change the plate resistors (and cathode resistor/cap according to rule of 66) on v2?
You would only lose the symmetric relationship between V1 & V2. You can still maintain the "66 rule" on V2 by choosing the applicable plate/cathode combination. Here's the thing; any combination can most likely be made to work, you just have to tune around it to suit your own liking.
On my 6V6 build, I used 150(2.2)/120(1.82) on V1, with 100(1.5)/100(1.5) on V2.
Yeah, I understand. I was planning to use the rule of 66 and use the bypass cap to tailor low end frequency response (along with the Ayan mod).
But I was wondering since most Dumble amps (including Two Rocks, etc) use symmetrical plate loads as far as I've seen them, there must be a reason. Hence my question. I remember reading something about harmonics
ToneMerc wrote:
Joost wrote:
jborders5 wrote:I'd mod it to a high plate using the #102 & #183 layouts before trying the HRM route.
So I've been reading a lot today and found a thread that said HAD liked symmetry in the valves, which was why his plate resistors were generally the same over V1 and V2. Now, as you know I do not want to mess with v1 but would that mean I can't change the plate resistors (and cathode resistor/cap according to rule of 66) on v2?
You would only lose the symmetric relationship between V1 & V2. You can still maintain the "66 rule" on V2 by choosing the applicable plate/cathode combination. Here's the thing; any combination can most likely be made to work, you just have to tune around it to suit your own liking.
On my 6V6 build, I used 150(2.2)/120(1.82) on V1, with 100(1.5)/100(1.5) on V2.
Hi,
I found out changing V2 to high plates (with corosponding Rcs on cathodes) but not V1 - the voltage at V2 lowers to around 180 VDC but V1 remains at round 200-210 VDC. So I played with some tubes and now there are nice volumes: 190/195 and V1 195/198. All pre amp tubes are now matched.
simple, when anode resistor goes up (cathode res. follow also), more "glassy" tone you can expect in (lead) overdrive. because ECC83 in OD section, is overdriven hardly and more higher harmonic develops in tone spectrum..
i had in one experimental version of #183 amp 68k resistors in V2 anodes, 5751 tube was there.. very nice rocky OD sound without "glass" in background..
OD sound is very complex, and depends mainly from certain tube stage configuration (anode , cathode resistor, grid stopper) and how much signal comes to the grid (hardly overdriven tube stage to clipping)..also symmetrical and assymetrical clipping(or, simple, bias of the stage), and how many OD stages we have are essential..
chapter 1) from merlin's first book describes this effects very good
"building tube preamps.."
personally i don't use "dumble values" in OD stage, i like to tweak amp to my own taste..regards
I have a 183 type circuit. The OD was a bit fizzy and the OD+PAB lacked ALOT of bass and was fizzy. Clicking PAB on, with OD already on, resulted in a major loss of bass and fizzy highs. The OD entrance values were correct and the pot was set correctly at about 23k to ground. There was 330k ohms to ground in total. Some here have mentioned that if this value is low, then the OD will lack bass. This was not the problem in my build.
I took boldaslove's subtle advice from earlier in this thread and rewired V2 and the PI to match HAD's layout. V1 was already correct. The fizz is now gone and PAB works beautifully with no loss of bass. I believe those short parallel runs of wire create a capacitive coupling between the plate and cathode that are important to the OD quality of the amp - the fizz is rolled off. I have read this in the past, but the level of improvement surprised me anyway. I should mention that this occurred with snubbers on V2. Here is my not so subtle advice: CHECK YOUR WIRING!
The 'take away' for me is that the component values in the schematic work if the wiring is done correctly. I won't be so quick to make additions and changes until I have already verified the wiring. As always, the guys here know what they are talking about. I just wanted to let you know my experience in hopes that it may help you. Thanks to everyone here. This is a great place to hang.
Thanks man. I was already taking Structos advice to let the amp settle in a little more before I make changes and then the first thing I'll do is check wiring
vibratoking wrote:I have a 183 type circuit. The OD was a bit fizzy and the OD+PAB lacked ALOT of bass and was fizzy. Clicking PAB on, with OD already on, resulted in a major loss of bass and fizzy highs. The OD entrance values were correct and the pot was set correctly at about 23k to ground. There was 330k ohms to ground in total. Some here have mentioned that if this value is low, then the OD will lack bass. This was not the problem in my build.
I took boldaslove's subtle advice from earlier in this thread and rewired V2 and the PI to match HAD's layout. V1 was already correct. The fizz is now gone and PAB works beautifully with no loss of bass. I believe those short parallel runs of wire create a capacitive coupling between the plate and cathode that are important to the OD quality of the amp - the fizz is rolled off. I have read this in the past, but the level of improvement surprised me anyway. I should mention that this occurred with snubbers on V2. Here is my not so subtle advice: CHECK YOUR WIRING!
The 'take away' for me is that the component values in the schematic work if the wiring is done correctly. I won't be so quick to make additions and changes until I have already verified the wiring. As always, the guys here know what they are talking about. I just wanted to let you know my experience in hopes that it may help you. Thanks to everyone here. This is a great place to hang.
