#102 Build started
Moderators: pompeiisneaks, Colossal
Re: #102 Build started
I thought you just posted your B+ on the power tubes as 411v?
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: #102 Build started
No, that was his PI input node, he did not post the plates the second time around.Structo wrote:I thought you just posted your B+ on the power tubes as 411v?
TM
Re: #102 Build started
B+ is the same as before, i get 482v at B+1 and B+2
I think I would try dropping 30V via zeners and I think i will be in the ballpark of 445v-455v, then tweak the values of the the dropping strings.
I think I would try dropping 30V via zeners and I think i will be in the ballpark of 445v-455v, then tweak the values of the the dropping strings.
Re: #102 Build started
amp is done, all issues are fixed, it turned out it was a relay miswiring. changed it and all is working as it should (I think).
this thing has some serious dynamics, and some serious gain on tap, I thought that with 2 gain stages I won't have enough gain, but man... more than enough, and i'm a high gain player usually.
I think I will mod the tonestack some, as I'm not really bonding with the clean channel.
any recommended mods before i close the book on this amp ?
a BIG BIG BIG thanks to all members of this great forum, and especially Aaron, I used his layout as a guide and it works wonderfully.
this thing has some serious dynamics, and some serious gain on tap, I thought that with 2 gain stages I won't have enough gain, but man... more than enough, and i'm a high gain player usually.
I think I will mod the tonestack some, as I'm not really bonding with the clean channel.
any recommended mods before i close the book on this amp ?
a BIG BIG BIG thanks to all members of this great forum, and especially Aaron, I used his layout as a guide and it works wonderfully.
Re: #102 Build started
So I tested the amp for a few hours using EHX EL-34, sound was BAD, even when properly biased.
changed it to Sylvania 5881, biased at 15W dissipation, it sounds AMAZING.
can't wait to try some telefunken 12ax7 and mullard 12ax7 i have lying around.
overall, amazing sounding amp, killer modern blues machine.
changed it to Sylvania 5881, biased at 15W dissipation, it sounds AMAZING.
can't wait to try some telefunken 12ax7 and mullard 12ax7 i have lying around.
overall, amazing sounding amp, killer modern blues machine.
Re: #102 Build started
so, after testing for a few days.
voltages are
B+1 456V
+2 456V
+3 422v
+4 314v
+5 307v
should i raise +4 and +5 or not worry about it ?
funny thing is, the monster with 5881 doesn't feedback as well as with the EL34s, guess it's time to order 6L6GC
voltages are
B+1 456V
+2 456V
+3 422v
+4 314v
+5 307v
should i raise +4 and +5 or not worry about it ?
funny thing is, the monster with 5881 doesn't feedback as well as with the EL34s, guess it's time to order 6L6GC
Re: #102 Build started
Just my opinioon but, I'd used caution running 456 V on those 5881.
Re: #102 Build started
Are these newer production 5881's or vintage?
From my data it looks like max Va for AB1 Push-Pull is 360v.
http://tubedata.milbert.com/sheets/127/5/5881.pdf
From my data it looks like max Va for AB1 Push-Pull is 360v.
http://tubedata.milbert.com/sheets/127/5/5881.pdf
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: #102 Build started
vintage, I bias them low and they don't seem angry in the amp.
I was thinking about Va being too high, but dunno..
I was thinking about Va being too high, but dunno..
Re: #102 Build started
I use vintage Russian military 6p3s-e (5881 equivalent) biased at 27ma in my small special build running at 496v. According to the data sheet plate voltage should be 250v (max 20w dissipation). No problem whatsoever.
I have a pair of the same in another 50w 102 clone amp at around 400v.
Sound great in both.
Dare I say I like them on par with a pair of vintage 7581 costing 20 times more?
YMMV implied.
Niki
I have a pair of the same in another 50w 102 clone amp at around 400v.
Sound great in both.
Dare I say I like them on par with a pair of vintage 7581 costing 20 times more?
YMMV implied.
Niki
Re: #102 Build started
I know it's been awhile but . . .
phsyconoodler wrote:I used 715s in one of my builds with excellent results. However, if you're going to try and orient the cap shields toward the lowest impedance they are apparently not the ones to use. According to aikenamps:715 orange drops are great too.
"Some higher-voltage film caps (typically the 1000VDC/450VAC and higher values, such as the Orange Drop 716P high-voltage units) use a "series-wound" technique that has two separate sections, side by side, with a common "floating" connection layer, usually at the bottom of the layer stack. These caps (like ceramic caps) will have no inherent shielding either. "[/i]
Just sayin..
Re: #102 Build started
I'm going to change all the caps to 6ps, the mustards sound real muddy and undefined in the OD, guess Dumble knows what he is doing....
Re: #102 Build started
the muddy sound was a result of forgetting (duh) to put the 68pf bright cap on the master.
now sound is good, but i will still try to change the caps and resistors to the original receipe
a few tweaks I'd like to try and would be cool to get some input
1. 500k ratio pot with a switch to turn it to 100k/346k/500k.
so i'll have a variety of response for different guitars.
2. 47pf fizz cap (I get osscilations with ratio pot at around 75k to ground
with humbuckers, thought this might tame it a bit)
3. having a 4pdt switch to switch to 68k slope and 10uf on the 2nd
cathode for a different clean sound (kinda like the Bluesmaster
tonestack on a ceriatone BM), I find the generic #102 clean tone to be
not so sparkly on a stratocaster.
that's about it for now I guess, any other suggestions ?
now sound is good, but i will still try to change the caps and resistors to the original receipe
a few tweaks I'd like to try and would be cool to get some input
1. 500k ratio pot with a switch to turn it to 100k/346k/500k.
so i'll have a variety of response for different guitars.
2. 47pf fizz cap (I get osscilations with ratio pot at around 75k to ground
with humbuckers, thought this might tame it a bit)
3. having a 4pdt switch to switch to 68k slope and 10uf on the 2nd
cathode for a different clean sound (kinda like the Bluesmaster
tonestack on a ceriatone BM), I find the generic #102 clean tone to be
not so sparkly on a stratocaster.
that's about it for now I guess, any other suggestions ?
Re: #102 Build started
the 68k slope is AMAZING for strat clean (with no LNFB engaged), it makes the strat ultra clean, kinda like a twin but with more note definition, without it, the highs are attenuated a bit, especially on the 2nd and 3rd strings.
it's not a huge change, but it's important for getting a really good clean blues tone.
moving to OD, there's too much treble, it cuts through really well, but not to my liking, i like the OD a bit more tame, that's why its helpful on a switch.
the 10uf didn't add anything that big to me, maybe more drive, but nothing helpful that i liked, left 5uf.
can't try the fizz cap cause the neibougher was here and complained about the noise (5 on the master is loud ?
).
still waiting for the 500k pot to get here, so i can try 100k/346k/500k ratio pot and see how i like that.
the 68k slope is definitely recommended for strat players on clean.
it's not a huge change, but it's important for getting a really good clean blues tone.
moving to OD, there's too much treble, it cuts through really well, but not to my liking, i like the OD a bit more tame, that's why its helpful on a switch.
the 10uf didn't add anything that big to me, maybe more drive, but nothing helpful that i liked, left 5uf.
can't try the fizz cap cause the neibougher was here and complained about the noise (5 on the master is loud ?
).still waiting for the 500k pot to get here, so i can try 100k/346k/500k ratio pot and see how i like that.
the 68k slope is definitely recommended for strat players on clean.