Tony, looks very nice. What does having the deep switch and the mid switch going at the same time sound like?
It's funny after I finished printing and laminating the face plates I thought about it thinking this is really kind of a contradiction and to some degree it is..If you en gauge the deep and mid boost at the same time you get a slight 3db mid boost.. So If you want just a hint of mid hump say 3db hit the boost and deep.. Keep in mind in this setting the bass control has very little effect but the mid control works better here...this is more than likely where Marcos .02 tweak mentioned above will work..
Cary
Thanks for the insight...
Yeah I want to try it with a FET.. That’s really interesting about your Gretch I had a similar effect going from my Strat to my Paul and thought that.... so it’s good to get a second opinion..It's great we have more of these early models being built here so we are beginning to reach some conclusions on how these amps perform..After building pretty much every D-Style OD amp it's clear he modified and voiced his amps to the ever changing sounds of the time..These are very 70's ish
As the amp sits stock with the 1 meg on V2b is like having the level control turned all the way up.. The 560k would make sense as this would be like having the Level set at 50% + taper.. So this to me makes sense..
The power transformer I used is the Music Man 200-130-200 I had laying around..This is the UK transformer.. If you wire the secondary in series with the bias tap and run the voltage doubler w/Loop gave me 448V exactly.. The transformer runs warm to the touch.. I used a Marshall style bias circuit..If you run across these transformers cheap get em they will work...
Tony
" The psychics on my bench is the same as Dumble'"
Hey Tony.
Nice to have somebody to compare notes with!
After 3 hours of playing you could damn near fry an egg on my PT. It's got me a little concerned, but it seems a lot of my amps are like that. I think everything just runs hotter in Texas. (For better or worse)
<i> "I've suffered for my music. Now it's your turn."</i>
crbowman wrote:Hey Tony.
Nice to have somebody to compare notes with!
After 3 hours of playing you could damn near fry an egg on my PT. It's got me a little concerned, but it seems a lot of my amps are like that. I think everything just runs hotter in Texas. (For better or worse)
:D
Implement 5 sec rule.. They say you should be able to place your hand over the PT for 5 sec.. The best sounding and feeling amps I have in the collection seem to run warm to slightly hot figure that one..One of my first amps was a JTM 45 Blues breaker.. I used a Hammond that doubled as a PT space heater.. 7 years ago and 3 continents later w/ touring act still works..PLAY LOUD!!
Tony
Last edited by talbany on Fri Feb 12, 2010 7:21 pm, edited 1 time in total.
" The psychics on my bench is the same as Dumble'"
Nice job on that Tony, thanks for sharing it. Your description of the amp is pretty close to what I found as well. I also concur about the FET input in this style amp, for both clean and OD. I set the trim for a 3db gain on the FET, I don't know if that's a lot or a little relative to what the real things had, but for me it gave just the right amount of gain to make the clean channel have a very slight bloom when really pushed, and make the OD really sing. The amp really sustains and feeds back at almost any volume using the FET input.
Another trick that Funk shared with me is to use a 12AT7 in the PI, I can't say that I noticed a huge difference, it did seem to give the OD a little more sustain and go into feedback at lower volume than a 12AX7.
I also had to try some different speakers to get a good sound out if it. Mine seemed best with a EVM12L, which took away some of that nasal midrange that I got with Celestion Heritage 30, Vintage 30 and the WGS G12-65. Seems like the OD entrance ditching a lot of the low frequency content really made the thing react badly with a speaker that is already a bit honky, the EV really helped balance out the tone.
What voltages are you seeing on the Preamp tubes? Mine seemed a little better with lower voltages than a 124 style amp. OD got a bit harsh up around 190-200 probably because there are no snubbers on V2 and no treble bleed.
Bill
wjdunham wrote:Nice job on that Tony, thanks for sharing it. Your description of the amp is pretty close to what I found as well. I also concur about the FET input in this style amp, for both clean and OD. I set the trim for a 3db gain on the FET, I don't know if that's a lot or a little relative to what the real things had, but for me it gave just the right amount of gain to make the clean channel have a very slight bloom when really pushed, and make the OD really sing. The amp really sustains and feeds back at almost any volume using the FET input.
Another trick that Funk shared with me is to use a 12AT7 in the PI, I can't say that I noticed a huge difference, it did seem to give the OD a little more sustain and go into feedback at lower volume than a 12AX7.
I also had to try some different speakers to get a good sound out if it. Mine seemed best with a EVM12L, which took away some of that nasal midrange that I got with Celestion Heritage 30, Vintage 30 and the WGS G12-65. Seems like the OD entrance ditching a lot of the low frequency content really made the thing react badly with a speaker that is already a bit honky, the EV really helped balance out the tone.
What voltages are you seeing on the Preamp tubes? Mine seemed a little better with lower voltages than a 124 style amp. OD got a bit harsh up around 190-200 probably because there are no snubbers on V2 and no treble bleed.
Bill
I was hoping you'd chime in here Bill.
I'm using a 12AT7 in the PI also. Probably doesn't get as much harmonic content as a 12AX7 but I'm happy. Definitely have plenty of gain. My voltages are probably similar to yours (PI - 285/290, OD - 195/200, 1st stage - 175/180) and I'm having no issues with harshness, and no excessive brightness, yet bright enough for anything I need to do. Overall, very well balanced tonally. Then again, I'm using an Emi RWB in an open back cab so that could be knocking some of the high end off.
I'm good with the 5 second rule up until about an hour and 1/2, after that it's more like a 1 second rule.
<i> "I've suffered for my music. Now it's your turn."</i>
wjdunham wrote:Nice job on that Tony, thanks for sharing it. Your description of the amp is pretty close to what I found as well. I also concur about the FET input in this style amp, for both clean and OD. I set the trim for a 3db gain on the FET, I don't know if that's a lot or a little relative to what the real things had, but for me it gave just the right amount of gain to make the clean channel have a very slight bloom when really pushed, and make the OD really sing. The amp really sustains and feeds back at almost any volume using the FET input.
Another trick that Funk shared with me is to use a 12AT7 in the PI, I can't say that I noticed a huge difference, it did seem to give the OD a little more sustain and go into feedback at lower volume than a 12AX7.
I also had to try some different speakers to get a good sound out if it. Mine seemed best with a EVM12L, which took away some of that nasal midrange that I got with Celestion Heritage 30, Vintage 30 and the WGS G12-65. Seems like the OD entrance ditching a lot of the low frequency content really made the thing react badly with a speaker that is already a bit honky, the EV really helped balance out the tone.
What voltages are you seeing on the Preamp tubes? Mine seemed a little better with lower voltages than a 124 style amp. OD got a bit harsh up around 190-200 probably because there are no snubbers on V2 and no treble bleed.
Bill
Bill
Thanks yeah!! I concur with the speaker choice.. I have not tried it with my EV still snowed in.. I can see where the EV would kill here..My voltages are 193/197 203/200/ 293/297 w 12ax..Loop is 250 on pin 1 CF 30v on cathode...Recovery is 235V pin 6 ..
I kinda like the AX in the PI on the clean channel but agree the AT kills in the OD..The the higher current handling of the AT along with the lower plates seems to push the grids in a more linear fashion so with the higher gain doesn't seem to experience the loading effect like the AX's .. For the clean channel the AX gives you that little bit of crunch/compression on the top when you lean into it that's kind of appealing..I started out using the JJ's but quickly went to my stash of NOS/Pulls.. Highly recommend old RCA's.. 7025's kept it smooth..
This thing already has sustain out the kazoot in OD so can't wait to implement the FET.. I can see why he didn't use a boost circuit here..The amp is 1 big boost circuit..In my mind this amp through a pair of EVL's played through 335 hollow or a semi w/ AT in the PI + FET would be sick.. Hey man can you turn that down..Ahhh!! NO!!
I'll Bet Lindley played his pretty loud!!
Tony
" The psychics on my bench is the same as Dumble'"
As I have said before, I really enjoy reading about this project.
Tony, have you tried this amp with the era-correct Altec speakers yet?
I agree that this circuit works best for slide guitar,but I wasn´t as happy with other applications.
FWIW: When I got my amp in 1979 the FET was set for a slight boost only,
3 dB may be realistic, never measured it.
The effect of the mid control is really very subtle, due to the .02 cap
wired to the bass pot, with some speakers almost inaudible.
With the Altecs and EVs it has some effect, slightly affecting the presence.
I remember trying fairly large values (.0022 and larger) for a midboost with good results in this circuit
Marcos
marcos,in another thread you mentioned a transition
model without the cap across the bass pot(in Rock mode)
I´ve tried that in my build https://tubeamparchive.com/viewtopic.php?t=10395
and I like it a lot!
Much more Bass if you want it
marcos wrote:As I have said before, I really enjoy reading about this project.
Tony, have you tried this amp with the era-correct Altec speakers yet?
I agree that this circuit works best for slide guitar,but I wasn´t as happy with other applications.
FWIW: When I got my amp in 1979 the FET was set for a slight boost only,
3 dB may be realistic, never measured it.
The effect of the mid control is really very subtle, due to the .02 cap
wired to the bass pot, with some speakers almost inaudible.
With the Altecs and EVs it has some effect, slightly affecting the presence.
I remember trying fairly large values (.0022 and larger) for a midboost with good results in this circuit
Marcos
Actually I have 4 Altec 417C's in pristine condition I was thinking of trying..Though in my mind this amp in OD and a speaker with an aluminum dust cap could be deadly..I did spend quite a while playing the amp last night and spent most of the time twisting knobs..The mid voice I can live with..The 1m treble has plenty of range..The bass control comes in all of the sudden then from about 9 oclock to 12 no real change then from about 1 to 3 oclock another big jump...How it responds also depends on the switch settings as well.. If there is a tweak there that will help this I would be down.. For the most part the amp is bass heavy..If I were to put out an amp with this type of stack I can hear it now.. I can twist and flip my way to some really nice tones on either channel..I just can't get both running together just yet.... Maybe the FET will help as well as some of your tweaks..I'll Get it!!
Tony, your triode voltages are sure nice and close together.
What do you attribute that to? The design or the tubes?
Those voltages were when I had the JJ's when I first fired it up after installing the loop..Right now I have some RCA pulls in there so they are mo different..I usually like to shoot for 190-200 V1a then up 10v to V2b.. since the amp is 100k 1.5 w/5uf throughout the voltages stay pretty uniform on up the line with the exception of V1a tone stack is usually lower and yes that's a relay...
As a side note here.. There is something to be said for keeping the 100k's 5uf throughout the amp..aside from the more transparent shift from clean to OD (just bigger/more of the same) it does bring a smoother more focused vibe about it all be it brighter and somewhat less textured (Smooth with very little artifacts riding on the notes of the d-g-b-e strings w/a little snarl on the E-A and double stoppin) in OD but still very musical and pleasing to the ear..I also think setting up the various gain stages uniform like this contributes greatly to the added sustain it has..JMO The Lindley Tone..
Tony
" The psychics on my bench is the same as Dumble'"
Hi Tony,
I had the same problems with the bass control.What worked for me was
changing to 1 Meg with a 10% taper.
I would still like to hear how you like the amp with the Altecs.
In my memory not quite as stinging as you might expect, but with a
metallic edge.
I am not sure that Lindley used Altec speakers much, although I read in one of his interviews that he did own a Dumble cab with Altecs that he would use for recording clean tones.
Marcos
two tone wrote:marcos,in another thread you mentioned a transition
model without the cap across the bass pot(in Rock mode)
I´ve tried that in my build https://tubeamparchive.com/viewtopic.php?t=10395
and I like it a lot!
Much more Bass if you want it
Hi twotone,
this was was actually one of the mods a tech did for me in 1987,
before I had seen the other amp.I liked it, but at the time thought it was maybe a bit too bass-heavy, so we changed to the .01 cap tweak I mentioned before.
This will get you into Skyliner territory, but with a 100K slope resistor
and the 510 pF treble cap.FWIW, I prefer the Skyliner values
Tony, that is a beautiful build, congrats. I have read that a 5751 at the PI produces interesting results... Funk, I think. Do you go through a range of tubes on every build?
angelodp wrote:Tony, that is a beautiful build, congrats. I have read that a 5751 at the PI produces interesting results... Funk, I think. Do you go through a range of tubes on every build?
ange
Ange
Thanks.. On this one I was going for the 70's vibe.. The NOS 7025 RCA's throughout and a quad of Black Plate 6L's.. I thought gave me the best results (Though the 5751sounds cool and will give it a try)..I wanted to stay true to the era so I didn't stray to far from the specs ..I did experiment a bit with voltages and tried a 12AX in the PI.. The 12AT for the PI in this case was I thought a big part of the amps charm and personality especially in OD..With the NOS and pull box I go through quite a few on this one to find the right set maybe a dozen...
For me personally if V1 voltages start at around 200v and above I lean tword the older tubes.. If I start V1 around 175-185 I'll lean tword the newer tubes.. That's just me..FWIW.. I highly recommend building one of these.. They are WONDERFUL!!
Thanks for the suggestion..
Tony
" The psychics on my bench is the same as Dumble'"
