UAD; PicoValve Part Deux

rolandson

rolandson

Well-Known Member
Acquired last fall or some such, sounded brittle. Tamed a bit of the shrillness with an EL34 (this thing takes any octal power tube) and 12AY's in the preamp section but still a bit 'ice pick in the ear - out the eye' sorta thing.

Unable to find a reliable schematic (multiple iterations) so I reached out to the best authority I knew of...
Andy Marshall (THD Hotplate guy)...the fellow who designed it. He immediately set about reminding me of why I think highly of him...he's genuine. Offered to take a look so I sent it up to Seattle.

Get a call from him asking what I was looking for...I said "Larry Carlton meets Joe Pass" and might have mentioned Tuck Andress trading fours with Anson Funderburgh but...

He tells me that's pretty close to the original design spec before marketing types started whining for "more gain, more gain, no...still more ice pick in the ear coming out the eye...gain." He also shared that mine doesn't have a serial number because it is one of a few prototypes he used to make changes for the people who sell ice picks.

It arrived Monday and...Mein Got he nailed it!

I've been tube rolling ever since. The EL 34 is gone, replaced with an old Sylvania 6L6, and the preamp now enjoys 7025's. I'll use that as the yardstick to gauge modern iterations.

Some say a 5 watt amp won't do a 12 inch speaker justice...
I guess it depends upon what one's definition of justice is. It might not rattled the fillings in one's wisdom teeth, but it has a quality of sound that I wouldn't hesitate to use while accompanying a competent double bass and keys.

Ladies and Gentlemen...meet my friend Pico

1721368654346.png
 
Last edited:
rolandson said:
Acquired last fall or some such, sounded brittle. Tamed a bit of the shrillness with an EL34 (this thing takes any octal power tube) and 12AY's in the preamp section but still a bit 'ice pick in the ear - out the eye' sorta thing.

Unable to find a reliable schematic (multiple iterations) so I reached out to the best authority I knew of...
Andy Marshall (THD Hotplate guy)...the fellow who designed it. He immediately set about reminding me of why I think highly of him...he's genuine. Offered to take a look so I sent it up to Seattle.

Get a call from him asking what I was looking for...I said "Larry Carlton meets Joe Pass" and might have mentioned Tuck Andress trading fours with Anson Funderburgh but...

He tells me that's pretty close to the original design spec before marketing types started whining for "more gain, more gain, no...still more ice pick in the ear coming out the eye...gain." He also shared that mine doesn't have a serial number because it is one of a few prototypes he used to make changes for the people who sell ice picks.

It arrived Monday and...Mein Got he nailed it!

I've been tube rolling ever since. The EL 34 is gone, replaced with an old Sylvania 6L6, and the preamp now enjoys 7025's. I'll use that as the yardstick to gauge modern iterations.

Some say a 5 watt amp won't do a 12 inch speaker justice...
I guess it depends upon what one's definition of justice is. It might not rattled the fillings in one's wisdom teeth, but it has a quality of sound that I wouldn't hesitate to use while accompanying a competent double bass and keys.

Ladies and Gentlemen...meet my friend Pico

View attachment 101954
Click to expand...
Congratulations! I know some do not like the EL84 power amp sound. I’ve had my share over the years, and found a few that I get along with, and others that I do not, but I do understand the differences that can manifest. A 6V6 is an excellent alternative imo, but with all things…the other build components come into play too. A good transformer set can make a big difference in one of these little amps.
 
It's proving to be a fun little guy, though...
I am not much for pedals and this thing ...

yeah, that.

Thatbastarddon said:
and found a few that I get along with
Click to expand...
The 34 was admirable in taming the ice pickiness of it as best it could. The brains at JC wanted gain gain gain, so Marshall delivered despite hating it. He was happy to have kindred spirit come along I think.

I imagine the 34 would sound less muddy if I kicked the preamp section up to 12AT's but I suspect that would come a noticeable increase in ice pick.

6V6's lack punch that this little fellow is deficient in to begin with, and @DirtySteve , I have indeed, and KT88. I don't have a KT66 or I'd have tried that too...

So now I'll fool around with newer iterations, mostly JJ's ...
(because I like them and their business model...plus Eurotubes is just across the river and up a hill from me and they've always been quite amenable to visits) ...
to see which best approximates the flavor that I'm getting with the Sylvania and 7025's. It's interesting to me that the subtitles between my collection of old tubes are so apparent with this little thing.

I'd often have difficulty hearing the differences between them (the old tubes) in the AB763 circuits I had available, though the distinction between them and new production tubes was instantly apparent...but on this platform there are clearly discernable differences between each...

and I've amassed a few tubes over the years...I think next winter's project has presented itself.
 
Last edited:
What I understand your amp was shipped with 12AX7 and 6L6GC stock at 12AX7 draws .5 amp max and a 6L6GC 900 mA
my guess is your amp was designed for 2 amps max fulfillment current draw
a EL34 draws 1.5 amp I love the sound of a quality EL34 but I run them a 470 volts DC on the plates

Larry Carlton's HRM Dumble amps run 465 volts on the plates

Larry Carltons Dumble right side up.jpg
 
67plexi said:
What I understand your amp was shipped with 12AX7 and 6L6GC stock at 12AX7 draws .5 amp max and a 6L6GC 900 mA
my guess is your amp was designed for 2 amps max fulfillment current draw
a EL34 draws 1.5 amp I love the sound of a quality EL34 but I run them a 470 volts DC on the plates

Larry Carlton's HRM Dumble amps run 465 volts on the plates
Click to expand...
Always great to read such informed input. As a matter of interest, is the blue lump of alien brains there to make it harder to someone to reverse engineer part of the circuit, or is it simply reducing vibration for some of the components?
 
Last edited:
rolandson said:
It's proving to be a fun little guy, though...
I am not much for pedals and this thing ...

yeah, that.


The 34 was admirable in taming the ice pickiness of it as best it could. The brains at JC wanted gain gain gain, so Marshall delivered despite hating it. He was happy to have kindred spirit come along I think.

I imagine the 34 would sound less muddy if I kicked the preamp section up to 12AT's but I suspect that would come a noticeable increase in ice pick.

6V6's lack punch that this little fellow is deficient in to begin with, and @DirtySteve , I have indeed, and KT88. I don't have a KT66 or I'd have tried that too...

So now I'll fool around with newer iterations, mostly JJ's ...
(because I like them and their business model...plus Eurotubes is just across the river and up a hill from me and they've always been quite amenable to visits) ...
to see which best approximates the flavor that I'm getting with the Sylvania and 7025's. It's interesting to me that the subtitles between my collection of old tubes are so apparent with this little thing.

I'd often have difficulty hearing the differences between them (the old tubes) in the AB763 circuits I had available, though the distinction between them and new production tubes was instantly apparent...but on this platform there are clearly discernable differences between each...

and I've amassed a few tubes over the years...I think next winter's project has presented itself.
Click to expand...
I have to admit that I just quickly glanced at this amp before opening my mouth. I don’t see these around my area very often(almost never). There aren’t many(any?) JC dealers local to me, and so they don’t show up unless ordered online. The used market locally probably never has any because anyone that orders one probably hangs on to it. So I am uninformed when it comes to the Jet City stuff.
 
Thatbastarddon said:
I have to admit that I just quickly glanced at this amp before opening my mouth. I don’t see these around my area very often(almost never). There aren’t many(any?) JC dealers local to me, and so they don’t show up unless ordered online. The used market locally probably never has any because anyone that orders one probably hangs on to it. So I am uninformed when it comes to the Jet City stuff.
Click to expand...
Worry not new friend, we all rely on our own experience when making initial evaluations, or at least we should...

Then the truly enlightened among us dig just a little deeper. Sometimes we get stood on our head when discovering that our original knowledge base was incomplete...

There was a time when I inked all PC board amplifiers to a specific category that was, ummm ... less than "becoming," shall we say? Andy has convinced me that my initial impression was misleading.
 
Last edited:
You must log in or register to reply here.
Back
Top