Are any/all of these modifications still in place?
Are there any others?
You don't make it easy to try and help you!
Considering that the first 2 posts you mentioned were from August of last year those problems are not relevant to this discussion and have long since been resolved. I only post new topics that are on a completely different vein of thinking about a different issue. I have posted in old threads before but never get responses so I start new ones for new issues.
I have continued to make modifications. I did keep the CC resistors where they are and have no complaints about them. I also kept the Spragues in place of the holy grails with positive effect.
)@Kassie What kind and how many speakers are you using? are you using a volumemod in your build? What cab?)
I'm using 1 Scumback M75-LD 16 ohm 65 watt in a combo cabinet that I built out of virgin solid pine. No volume mod.
As far as the distortion. I reflowed a lot of solder points. Repositioned some of the heater wires and changed out the PI tube and the power tubes and now it sounds great. I suppose the heater voltage issue wasn't as much of an issue as I originally thought. (I took it to a band practice of a friend and when he plugged into mine they all loved it so much he never used his Fender amp the rest of the night because they said it sounded so much fuller, clearer, and made them sound so much more professional they didn't want to use the other amps. ) Can't really ask for much more than that.
The only real issue any one had was the hiss when they were between playing sets. I have since narrowed down the noise to a grounding issue that I'm working on correcting. Does anyone have any suggestions about silencing grounding hiss? Since there are 3 wires from the back of all the filter caps would it be better to reduce this to chaining them all together and grounding it with one larger gauge grounding wire?
jckid649 wrote:
The only real issue any one had was the hiss when they were between playing sets. I have since narrowed down the noise to a grounding issue that I'm working on correcting. Does anyone have any suggestions about silencing grounding hiss? Since there are 3 wires from the back of all the filter caps would it be better to reduce this to chaining them all together and grounding it with one larger gauge grounding wire?
Good everything is resolved. About the hiss. It does that. Hiss usually is not involved with poor grounding.. that's hum. Hiss is just white noise, caused by gain. I use Metal film resistors for all the v1 positions.. the rest carbon film.. Carbon Comp is really hissy btw. Furthermore invest in a really good 12ax7 for v1. A silent one. Definately not a high gain one. And you can change the Volume pot for a conductive plastic one instead of the normal carbon.
Furthermore there are a couple of pages of possible alternative grounding connections in the preamp. Read the express build manual.. around page 50 or so.
And if you really want to have maximum signal to noise ratio... you need to wire v1 point to point... (real point to point, resistors/caps on tube sockets).
Also be aware that the more gain = more hiss, more treble = more hiss.
jckid649 wrote:Considering that the first 2 posts you mentioned were from August of last year those problems are not relevant to this discussion and have long since been resolved....
They (the 2nd one explicitly) relate to low heater voltage readings which is the subject of this thread, so clearly hasn't been 'resolved' (but may not be relevant)
I think it's helpful to give full disclosure of any modifications if you're asking for help, as things like substituting carbon composition resistors for metal film in certain places *will* give you much more hiss, but hey, I guess we can to agree to differ....
Also, some meters are not dead on accurate. I've blown up many through the years..lol. And some that didn't blow up gave some weird readings.
The 5.7 v on the heaters. Depending on what your wall voltage is, and what taps your are using. And if you have a good calibrated meter. Take all that into account, 5.7v is probably close.
One thing to try, is pull all tubes and measure the heaters..no load.
See how much different that is compared to your 5.7v with tubes in.
) Can't really ask for much more than that.
