HawkeyeKane
2061 posts
Sep 26, 2013
7:10 AM
|
@arnenym
"The 6L6 amp and the 3 x 6V6 amp are different animals.
You can not compare them."
Then why does Randy say this on his 3X6V6 page?
"I will not duplicate the explanation of the power supply and preamp circuit as this information can be found on the 6L6SE project page."
----------
Hawkeye Kane
|
Barley Nectar
67 posts
Sep 26, 2013
7:47 AM
|
I used Randy's VJ preamp when I built the Honker. He has a certain amount of distortion built into that preamp just for harp. I did not alter his design at all for fear of screwing up the tone. The guy knows his stuff. I would say, build as speced. JMO as always...BN
|
HawkeyeKane
2062 posts
Sep 26, 2013
8:31 AM
|
@Barley
Well normally I'd agree with you. Build per spec. But if the tone control in his design really is a volume diminisher, I'm not sure I like that.
----------
Hawkeye Kane
|
Barley Nectar
70 posts
Sep 26, 2013
8:38 AM
|
Practicly all tone controls throw away signal. There are very few active tone stacks out there. If your worried about this, put a switch on the ground wire for the tone stack and kill it. I did this on my Super Princeton but I don't like the results. Makes a huge leap in volume but guess what, no tone...LOL. You are building a small simple amp, simple is best. Don't mod it before you'v heard it...
Arnenym knows what he is talkin about. He has built both of the circuits. See his last post in the 'Harp amp circuitry" thread...BN
Last Edited by Barley Nectar on Sep 26, 2013 8:52 AM
|
Rick Davis
2441 posts
Sep 26, 2013
9:15 AM
|
Yes, most tone controls throw away signal but there is often a tone stack gain recovery stage -- usually a triode in half of one of the preamp tubes. I don't see that here. Did I miss something?
I think this tone control is high cut only. That reduces the signal and I don't see anything that puts it back.
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
|
HawkeyeKane
2064 posts
Sep 26, 2013
9:29 AM
|
Would a 5751 in place of the AY7 help compensate for the signal loss?
----------
Hawkeye Kane
|
Rick Davis
2442 posts
Sep 26, 2013
9:35 AM
|
No, that is different. The tone stack gain recovery stage is after the tone control. It bumps the signal gain back up after the tone contol wipes some of it out. Ask the circuit designer about it. Maybe he has a solution, or maybe I am just wrong.
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
|
HawkeyeKane
2065 posts
Sep 26, 2013
9:52 AM
|
Here's the schematic if it helps...but from what I can tell of it, there's only one connection to the preamp tube (pin 1) from the tone control via C2.
Lone Wolf 3X6V6SE
----------
Hawkeye Kane
Last Edited by HawkeyeKane on Sep 26, 2013 9:56 AM
|
Barley Nectar
71 posts
Sep 26, 2013
10:15 AM
|
Ahhh yes, the schematic, now that, I can read. Looks like he has extra gain it the second stage. Don't get me wrong, I'm not "All Knowing" either. I just know Randy knows the theory and what good harp tone is made of. Sharp guy...BN
|
HawkeyeKane
2066 posts
Sep 26, 2013
10:23 AM
|
Here's another question open for recommendation....
When I go to build my cab, should I orient it horizontally or vertically? I know some would say it makes no difference. But in my mind it kind does, and not just for aesthetics either. I've had a horizontal configuration in my head this whole time, with the plans to put it in my amp stand so it gets it off the floor and shoots it higher for me to hear better. But if I arranged it vertically like the DT, it'd get at least one speaker up higher with its inherent design. What say you all?
----------
Hawkeye Kane
|
BigAl
7 posts
Sep 26, 2013
1:52 PM
|
I like the idea of a vertical cab, gets one of those speakers off the floor without a stand. I place on amp on the floor and one on a chair directly behind it. I don't like the stands that tilt the amp back, seems to promote feedback easier. Without the tilt, I think I can hear just as well. Yeah, digging' the vertical cab.
|
HawkeyeKane
2068 posts
Sep 26, 2013
2:12 PM
|
Well......now I'm starting to get the itch to make this thing a 4X8. LOL!!!
----------
Hawkeye Kane
|
5F6H
1671 posts
Sep 26, 2013
2:36 PM
|
@Rick "Yes, most tone controls throw away signal but there is often a tone stack gain recovery stage -- usually a triode in half of one of the preamp tubes. I don't see that here. Did I miss something?
I think this tone control is high cut only. That reduces the signal and I don't see anything that puts it back."
Randy's preamp design has 2 series triodes (with a voltage divider between them) before the tone stack, for good grind early on. Then, as you say, this signal is fed straight to the power tube after the tone stack.
This isn't unheard of, the Selmer Corvette amp had a similar topology, the Electar tube 10 (and a few others) only differ in the respect that they have a volume control, instead of a fixed divider, between the first 2 triodes, then the tone stack feeds the power tube direct.
If you translate the idea to a push-pull amp, it's really not that different to a tweed bassman style amp, the tone stack there feeds the PI rather than a true recovery stage...if it were single ended, the amp wouldn't need the PI and the stack would feed the power tube direct.
----------
www.myspace.com/markburness
http://www.facebook.com/markburness
Last Edited by 5F6H on Sep 26, 2013 2:37 PM
|
Rick Davis
2444 posts
Sep 26, 2013
2:47 PM
|
Mark, does turning down the tone control reduce the volume of the amp in this case?
I believe the VHT Special 6 combo amp is the same way. The pull boost cuts out the tone stack and sends the entire signal to the power section. It is not really a boost, but a non-reduction.
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
Last Edited by Rick Davis on Sep 26, 2013 3:02 PM
|
Barley Nectar
72 posts
Sep 26, 2013
3:02 PM
|
Stacked, Top speaker tilting back about 30 deg w/the chassis between the two. That would be my ultimate design. Would look cool with round or other shape holes for speakers and grill cloth. Might as well make it look unique...BN
|
HawkeyeKane
2069 posts
Sep 26, 2013
3:44 PM
|
@Barley
Might be a little impractical. Keep in mind, this amp will be my gigly workhorse. Maybe I'll build an art deco amp on down the road. But this one's gonna need to be rugged and look classy at the same time.
----------
Hawkeye Kane
|
Barley Nectar
74 posts
Sep 26, 2013
3:57 PM
|
Impractial, hows that impractial? Two speakers, controls in the front. Sounds like 5,000 other amps to me.
|
HawkeyeKane
2070 posts
Sep 26, 2013
4:37 PM
|
I'm referring more to the factors of chassis planted between the two speakers and the artistic cutouts. The chassis design per specs is to go vertical like the Fender tweeds, and I like that. I wouldn't be comfortable with the tubes going horizontally, and modifying the design to have the tube sockets hang down isn't really in the cards for me. I'm not trying to bash your idea dude. I think it's a killer idea. It just doesn't quite fit with the overall finished product I have envisioned for this. As for unique, I'm really starting to think I'm gonna go bare hardwood again on the cab like I did with my Zoo.
But this time with a better construction method and a nicer finish.
----------
Hawkeye Kane
|
Barley Nectar
80 posts
Sep 27, 2013
8:01 AM
|
Hawkeye, Did you get my Email about the tube guy?
|
HawkeyeKane
2072 posts
Sep 27, 2013
8:07 AM
|
Yes I did Goose. I thought I sent you a response....guess I didn't though. Sorry bout that.
EDIT: I just shot him an email now to see if he has any tubes of the same brand.
----------
Hawkeye Kane
Last Edited by HawkeyeKane on Sep 27, 2013 8:20 AM
|
5F6H
1672 posts
Sep 27, 2013
8:56 AM
|
@ Rick "Mark, does turning down the tone control reduce the volume of the amp in this case? I believe the VHT Special 6 combo amp is the same way. The pull boost cuts out the tone stack and sends the entire signal to the power section. It is not really a boost, but a non-reduction."
Turning down any "hi cut" control reduces signal sent to the next stage. The VHT, like a champ & BF/SF Fenders, has a full tone stack between first & second stages, with a recovery stage before the power tube.
Boost/non-reduction...they're relative terms, depends where your start point is? ;-) As long as you have between "something" & "everything", it's up to the designer to decide what's normal/attenuated/boosted.
The non-boosted VHT is like a SF champ (but with fixed tone stack values instead of pots & an extra compound tone control - 5F2A style - accross the volume control), the "boost" function adds some resistance between the tone stack middle control & ground - more gain than a SF/BF circuit...but not as much as a 5F1/5F2A. The boosted VHT still has some losses at the tone stack and at the additional tone control. A 5F1 (no tone pot) with the volume full up (just a coupling cap & 1meg grid load for the next stage) is as much boost/non reduction as you reasonably get for this kind of design...but that would be pretty useless for harp.
The losses from a tone stack, or high cut control are usually deemed useful for harp.
----------
www.myspace.com/markburness
http://www.facebook.com/markburness
Last Edited by 5F6H on Sep 27, 2013 8:58 AM
|
Rick Davis
2450 posts
Sep 27, 2013
11:00 AM
|
Mark, thanks. I appreciate the info.
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
|
HawkeyeKane
2075 posts
Sep 27, 2013
2:20 PM
|
Ditto Mark. On my next build, I may try your KT66 design. Always been curious about kinkless tetrodes.
----------
Hawkeye Kane
|
Rick Davis
2452 posts
Sep 27, 2013
4:56 PM
|
My 5F2H amp came with a KT66. I found it to be sonically indistinguishable from a 6L6 when I swapped them. Not a big surprise since it was manufactured to be the equivalent of (and to compete with) the 6L6.
----------
-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
Last Edited by Rick Davis on Sep 27, 2013 5:44 PM
|
