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Post by doveman on May 13, 2012 9:06:45 GMT -7
I'm pretty happy with the way this thing sounds around the house with the volume on nearly zero ... still has attitude. Haven't tried it out yet ... so not planning anything too soon but doing some research ... here's what I know.
This amp seems pretty loud if I take it up to operating levels ... no doubt this is a loud 32 watts. I have two other amps ... a Brown Note D'Lite 22/33 that I built with an excellent master volume but it gets most of the edge from the pre-amp. I also have a Richter Supra-Luxe Tweed (30w with two 6L6). I really, really, really like what that amp became after installing a VVR in it. I can dial it down from 30 watts to about 3 watts and it sounds the same. Granted it's a cathode biased amp. But the results were incredible.
I have contacted Hall Amplification and started asking questions about their VVR3 (for fixed bias amps) just to get ahead of the curve. These work for amps up to about 50 watts.
My thought is along these lines: The Treble and Bass seem like gain controls for those frequencies and add gain passed 12:00. The volume is a pre-PI volume control that seems to work pretty effectively. If I were to add the VVR3 to control the B+ voltage and bias on the power tubes, I could have incredible control while gigging and at home.
I'm not a big fan of attenuators. I actually had the first one ever ... the Altair PW-5 (sort of a toaster oven but it worked on my original Mesa Boogie). Anyway ... all attenuators have the same effect on tone for me ... and the 11db setting on the Brake Lite would still be loud. The Air Brake is way more expensive. I really like the VVR from my experience better and it's cost effective compared to any of the attenuators if it would work.
Anybody tried this before or would I be breaking new ground?
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Post by kcraig on May 13, 2012 16:47:48 GMT -7
Thats a good idea. I use a Brake Lite SA with my RT 66. Usually never past 2. Depends alot on the room. The 66 can be very LOUD ampand add some pedals adds more boost. I use a Z-Best 2x12. The amp does get fatter and dirtier with theV, T & B turned up. I use guitar vol/pups to control volume. The BL works for me without tone sucking. I think there have been requests for a 1/2 power switch or MV on the 66. I wanted a lower wattage/power/volume amp also. The Maz 8 is a sweet little Beast!! I had mine a few months now and I really dig it. Doc builds what he builds for a reason. I'm sure someone here has more info than I do. Welcome , Kim
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Post by doveman on May 13, 2012 18:45:46 GMT -7
I can tell you that Sara Richter (builder of my Richter Supra-Luxe) had never considered the VVR in the tweed until I asked about it. She helped me a great deal and after I finished mine, she introduced that option in her Supra-Luxe amp. It was pretty cool to see the idea actually make it on to her amp as an option. So while I have no need to make any rush changes ... I'm just thinking about it and asking questions. I'm a tweaker ... but I have some absolutely great gear due to the habit. Thanks for the response ... the RT66 even sounds good with the volume low in the house. I hope to have an opportunity to jam with it soon.
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Post by doveman on May 17, 2012 16:48:08 GMT -7
I decided to give the Brake Lite a try ... can always go for something different later ... but I see a lot of guys using it.
;D
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Post by doveman on May 22, 2012 6:59:14 GMT -7
I'm still thinking about the VVR (Variable Voltage Reduction ... either SkipZ or Hall Amplification) as a better solution than the Brake Lite I received yesterday. While I'm giving it some time, I asked a few more questions of both of these guys today.
It's incredible what the Hall "cathode based" version does with my 30w Richter Tweed Supra-Luxe ... scales the whole amp. Totally variable up and down the scale ... but scouring the internet I don't see that anybody has tried it on any Zs.
Anybody know of any good reasons not to do it? Talk me out of it if there is.
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Post by doveman on May 28, 2012 9:05:58 GMT -7
OK ... I decided that this experiment needs to be done ... VVR on the RT66. I ordered the SkipzCircuits VariWatt-FX kit for $65. It's more modular than the Hall Amplification VVR3 which is a single unit. I think the modular circuit will give me a few more installation location options. So in a week or so, we'll see what I have ... As a point of reference, here's a couple of clips of my Richter Supra-Luxe 30 watt tweed with the cathode biased Hall VVR version. VVR starts at about 1:00 ... And some cleans ... I'll let you guys know if it works or not ....
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Post by Deleted on May 28, 2012 11:34:11 GMT -7
I'll be interested to hear the out come.
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Post by Sean on May 29, 2012 4:34:00 GMT -7
Very cool. Will be watching this thread.
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Post by doveman on Jun 1, 2012 18:07:39 GMT -7
Update: The kit is on the way. I got the advance instructions for how to do it and I hesitate to make these changes. It's a bit more invasive than the VVR (for the simpler cathode biased amp). So far the only solder joint that has been touched in the amp is the simple modification I made to add the bias points ... completely reversible. I will continue to study it a bit ... but I doubt that I will make this adjustment just simply out of respect for the amp and the maker. Not saying it wouldn't work or is a bad design ... I imagine it would be great. If it was a few simple wires and completely reversible without a lot of solder joints touched ... it might be different. Chalk this one up to educational expense
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Post by Deleted on Jun 5, 2012 23:09:23 GMT -7
I'm pretty happy with the way this thing sounds around the house with the volume on nearly zero ... still has attitude. That is one of the things that stick out about the Doc's amps. They sound great at any volume. I found it near impossible to dial in a bad tone.
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Post by doveman on Jun 6, 2012 20:14:36 GMT -7
Well ... I did it ... SUCCESS! Installed the Hall Amplification VVR3 version ... came in the mail this afternoon. Works well ... indications are good, sweet at low volumes. I won't be able to crank her up until tomorrow afternoon ... but it seems to work just like the other amp. For those who don't appreciate mods (as many of you have said) look no further. Here was my plan ... on the original route 66: Here's what it looks like ... there's one pot on the back that scales the whole amp. Other controls still work the same. I'm stoked ... and hopeful that this will really work for me. Won't need the Brake Lite either. More testing tomorrow. ;D EDIT: Couple of other things I should mention: - This was Hall device was a bit simpler than my interpretation of the Skipz device ... but it's still a fairly involved mod. This is not for everyone for sure. But I love the VVR approach enough to try it on a second amp.
- Only 5 wires to the amp (BIAS IN & OUT, B+ IN & OUT, ground). That was pretty easy.
- Then the 6 wires to connect the ganged pot to the device. They usually have these already mounted on the board but I was thrilled to see the pot separate. Better location although more work in wiring.
- There are 5 holes drilled to mount board and NTE. You have to be really careful and capture drill shavings.
- Still need a step washer to convert the 5/8 hole I used (already there) for the pot. Needs a knob too.
- One more decision to make ... the current set up takes the amp to 10% power ... that low it adds a scratchy sound to guitar pots. I can either increase the "floor" a bit (like 20%) by changing two resistors on the VVR board OR move a couple of resistors and caps at the preamp tubes. I chose the latter in my tweed but will play it a while before deciding.
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Post by Phil (aka Phil) on Jun 7, 2012 14:11:56 GMT -7
Oh no!!!!! I must avert my eyes! NOOOOOOOOOOOOOOO!!!!!
Just kidding. As I said before I don't like modding Z's but I'm not one of those guys to make it personal or hold some kind of grudge about it. Also the electrical engineer/amp builder/geek in me is curious how well the power scaling works.
Nice job on the install by the way. It looks nice and clean.
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Post by doveman on Jun 7, 2012 16:13:50 GMT -7
Also the electrical engineer/amp builder/geek in me is curious how well the power scaling works. Thanks for the kind comments ... and forgiveness. LOL I really like the way it sounds. I think I've figured out the minor adjustment to relieve the scratchy pots. I expected it after the tweed but I want the whole 90% reduction. It's a little different than the tweed ... simpler in fact. Once that's done ... she'll be just about the playing. I'll post either some test clips ... or maybe just record some tunes with it soon. RT66 that can be a killer stage amp and a bedroom amp too ... sweet. Combined with the RC, Timmy, BB and Dispatch Master (delay/reverb) get really nice cleans all the way to the RT66 dirt ... and at any volume. Stoked
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Post by doveman on Jun 8, 2012 11:00:23 GMT -7
pix ... 10 = 462v B+ and 38 mA Bias 100% volume, 0 = 46v B+ and 3.8 mA Bias (10% volume)
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Post by doveman on Jun 8, 2012 12:24:41 GMT -7
Last step ... as expected at very low volume some DC voltage "leaks" to the guitar pots ... making them sound "scratchy" when they are moved. The following adjustment fixes that ... - Remove 1 meg resistor from input jack
- Place a .047uf cap (same as in front of 12AX7 grids) between input and pin 9 on EF86
- Place the 1 meg resistor between pin 9 and ground
Scratchy pots are gone at lowest volumes ... still sounds good too ... so I can keep 90% VVR reduction. That's it ... she's done ... experiment complete ... happy camper! ;D
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Post by doveman on Jun 9, 2012 9:47:10 GMT -7
Here's a clip ...
If you adjust the sound up on the PC and compare the tone ... I think it's the same. And cranked ... this thing is a hammer.
;D
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Post by Deleted on Jun 9, 2012 21:15:47 GMT -7
Sounds good. How about cleans as you turn down the VVR? Do you retain them?
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Post by doveman on Jun 10, 2012 10:10:15 GMT -7
Sounds good. How about cleans as you turn down the VVR? Do you retain them? Here ya' go ...
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Post by Deleted on Jun 10, 2012 11:06:56 GMT -7
Sounds great. Congratulations!
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Post by doveman on Jun 10, 2012 13:41:50 GMT -7
Thanks ... I'm happy with it now.
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Post by doveman on Jun 16, 2012 5:52:07 GMT -7
Edit: FOUND THE FIX FOR BLOWING THE MOSFET - SEE POST #27 but read on to see my frustration in the search. LOL: I think you have to keep in mind that the VVR3 is "up to 50 watts". While considering the RT66 32 watts ... it's definitely got more power than that ... What I did was replace the KT66 with the Golden Lions (25w > 30w tubes). Rebiased with the 5A4R ... trying to test the sounds .. immediately VVR started responding strangely. Testing and trouble shooting indicates the MOSFET overheated and it blew. Now the VVR knob adjusts the BIAS but not the B+ voltage. So ... I may need to consider location/heatsink options to keep the MOSFET cooler (especially with these beefier tubes) So once I figure out the part numbers, I need to order a MOSFET and a Zener diode that sits on the board (recommend to replace together) ... probably $15-$20 or so. I'm also going to investigate MOSFET locations/heatsink options that would dissipate heat more effectively. The MOSFET is the black device with 3 prongs that dissipates heat to the chassis ... just don't want it to get too hot. Just want to post this for anyone doing this in the future. I'll post the solution if I figure it out. Amp would still work if you leave the VVR on 10 ... but this thing was SWEET and I want it back!
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Post by prspastor on Jun 16, 2012 6:15:57 GMT -7
So sorry about this Doveman. I do like how you mounted the board Dumble style.
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Post by Phil (aka Phil) on Jun 21, 2012 3:59:27 GMT -7
Do you have any data on how much wattage your Route 66 was actually producing? I'm just curious. Even though I've had mine since 1998 and have had it "on the bench" several times I've never checked!
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Post by doveman on Jun 21, 2012 4:39:41 GMT -7
Do you have any data on how much wattage your Route 66 was actually producing? I'm just curious. Even though I've had mine since 1998 and have had it "on the bench" several times I've never checked! I have not ... don't know of a way to check. But the SPL/DB meter shows "max" DB about 20% higher than my other low-30's wattage amps. I'd say it's probably 38-40 watts. Then I guess you might add 5 watts for the Golden Lions? The VVR discussions I have had say that 35w-50w might need heat sinking. That's probably what I experienced. But should be getting new mosfet soon.
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Post by Deleted on Jun 21, 2012 9:47:02 GMT -7
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Post by Phil (aka Phil) on Jun 24, 2012 5:16:08 GMT -7
Do you have any data on how much wattage your Route 66 was actually producing? I'm just curious. Even though I've had mine since 1998 and have had it "on the bench" several times I've never checked! I have not ... don't know of a way to check. But the SPL/DB meter shows "max" DB about 20% higher than my other low-30's wattage amps. I'd say it's probably 38-40 watts. Then I guess you might add 5 watts for the Golden Lions? The VVR discussions I have had say that 35w-50w might need heat sinking. That's probably what I experienced. But should be getting new mosfet soon. Just measure the voltage the amp is putting out to the speaker at full output, then square that voltage and divide it by the speaker impedance. So, if you get 20V into an eight ohm load you've got 50W (20X20/8=50).
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Post by doveman on Jun 24, 2012 10:08:50 GMT -7
I fixed the VVR3 today. It was in fact the MOSFET/Diode. While I did try to move the MOSFET to another place on the chassis, it added some noise. So for now ... I'm going to leave it in the original location and avoid full volume and a VVR setting of 5 (stresses the mosfet the most at 5). I have proved that does not work. I also have a backup mosfet and diode. I would like to make it bullet proof ... so will be thinking about heat dissipating options over the next few weeks. Sure does sound good though ...
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Post by doveman on Jun 30, 2012 8:00:34 GMT -7
EUREKA! FINAL SOLUTION (I think ... with the help of my theampgarage forum buddies). If you remember I blew the first MOSFET for some unknown reason. The problem was that I had the VVR3 directly following the rectifier. That's a pretty harsh environment for the VVR unit. I made an adjustment to slip it in after the first cap but before the rest of power circuit. Dana's VVR3 instructions clearly show the VVR3 following the first of 4 filter caps but my Dr Z only has 3 caps ... I did not notice that there were 4 in his instructions. These are boiler plate instructions for most amps ... expecting that the amp tech knows a bit more than me ... but I'm learning. Not only does this make sense ... fix the problem ... it's also a neater and more tidy solution. I tested it at the 3:00-3:00-3:00 setttings with the VVR on 5. You can still put your finger on the bolt head holding the MOSFET (hot but not uncomfortable) and the surrounding aluminum is warming nicely (seems to dissipate just fine). Excellent! Here's the final fix. Notice it is much cleaner around the cap can to VVR: I might simplify the ground next time I have the head out of the cab and have a chance to pick up some connecters.
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Post by Deleted on Jun 30, 2012 13:00:27 GMT -7
Lookin' good.
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Post by doveman on Jan 25, 2015 8:05:07 GMT -7
Update: VVR still working great after a couple of years. I play this amp head through a Scumback M-75 2x12 4 ohm set up. Selecting 1x12 8 ohm when playing low at home. Still the best $50 I've ever spent ... and I've spent a lot on gear over the years!
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