plotting out deluxe rvb with some dumble bits

[didit]

I used the MM fat stack OT. FBFDR-O-FS

Had presumed F-DELUXE-FS-OM. Curious how you believe that 8K vs a more conventional 6.0K impacts your result.

..

[martin manning]

I can say that an 8k load line looks a little better, passing just below the knee, where a DR 6k6 load line passes just above it.

[didit]

I can say that an 8k load line looks a little better, passing just below the knee, where a DR 6k6 load line passes just above it.

The Mercury specs for various DR products call out 6.0K and 6.1K as the "conventional" primary. A gently circled topic a while back when people doubted Pacific Trainwreck "clones". My take away -- a singular nominal impedance spec is based on various tape-measure assumptions that can vary from one portfolio/manufacture to another. That said, Mercury undoubtedly applies the same set of metrics across all their transformers.

Asking as "ears" testing on a few limited experiments favour the higher primary impedance even when the power efficiency is on the downslope. And yes, below the "knee".

Asking too, as the next project here will be smaller "special", so confirmation will bias my hopes. Roughly fits in the range and spirit of this build; ~20W power point, though without an OD and perhaps just reverb for embedded effects. Built on a Princeton chassis using an 8K Dynaco OPT, packed in combo with the room for 12" speaker and an interior volume equal to a DR.

Best ..

[martin manning]

Hammond lists 6k6 primary for their DR replacement 1725H (for Fender 125A1A). MM may have measured some originals, but my math says 6K would only take things further afield, beyond 200% Pa max assuming 400V B+. Many DR run higher voltage at idle, but may sag down to 400 or so with signal. I'll bet the 8k Dynaco will sound great.

You can hear the 8k result in the Vimeo clip above, and I had the pleasure of hearing Ian and his amp live in a small club setting last night. Both sounded great! Plenty of volume mic'ed up, and the sound guy did a great job balancing the three guitars.

[imo1]

I'm not able to parse out the individual pieces that have contributed to the success of this build, but I am very pleased with it. I have a few deluxe reverbs, as well as a number of other blackface Fenders, and I find this amp to easily surpass any of the other Deluxes I've owned. My desire, as stated at the beginning, was to build an amp that had all the qualities of a Deluxe that I loved, but with a more powerful and cleaner low end. I also figured I would use the channel 1 as an OD channel, and implement the PAB.

As I've stated a few times, I will never have the engineering chops of many on this board, but I do get to consistently work and use designs in real world applications, and have been doing this for a long time, so I feel like I have a pretty good understanding of guitar amps "in the wild", especially Fenders.

To my ears, this amp is one of the best I have ever played of any design. This, of course, is based on my playing style, which might not be the same for other players, but does seem to hit a swath that a lot of folks are going for.

What it does is produce the classic "blackface" sound, but is able to hold it together through almost its whole volume range. The clean sound has significantly more low end than a standard Deluxe reverb, which is where I was struggling in the past. When I kick in the OD channel(in line with the clean) it has clarity and sustain that is kind of mind blowing. The only "gain" pedal i use is the "Klon" side of a Duelist, with the gain on maybe 1, so the boost is really just a slight clean boost for volume on solos.

I work with the folks at Mercury and can ask where they got the specs for this OT.

[martin manning]

The FBFDR-O-FS OT description:

Fender | Deluxe (65 Reverb Reissue), Deluxe (68 Custom Deluxe Reverb), Deluxe (Blackface/Silverface-Reverb) | Output Transformer
FatStack Upgrade! — 8k primary — Single 8 Ohm Secondary

Specifies 8k, and covers a lot of ground. I've never measured a DRRI OT, anybody?

[martin manning]

I'm not able to parse out the individual pieces that have contributed to the success of this build, but I am very pleased with it. I have a few deluxe reverbs, as well as a number of other blackface Fenders, and I find this amp to easily surpass any of the other Deluxes I've owned. My desire, as stated at the beginning, was to build an amp that had all the qualities of a Deluxe that I loved, but with a more powerful and cleaner low end. I also figured I would use the channel 1 as an OD channel, and implement the PAB.

Some of it has to be the large (huge?) reservoir capacitance and the SS rectifier. I think the low B+ (as compared to many DR) and 8k primary have something to do with it too, keeping the load line in a good place.

As I've stated a few times, I will never have the engineering chops of many on this board, but I do get to consistently work and use designs in real world applications, and have been doing this for a long time, so I feel like I have a pretty good understanding of guitar amps "in the wild", especially Fenders.

Not to worry, not many here or anywhere will have your guitar chops!

What it does is produce the classic "blackface" sound, but is able to hold it together through almost its whole volume range. The clean sound has significantly more low end than a standard Deluxe reverb, which is where I was struggling in the past.

See above, and I'd guess the Fender stack in the clean preamp is giving you the BF sound. That goes away in PAB, though. I will have a look at the curves for the OD stack and compare.

[BarryW]

I often use a pro/vibrolux style transformer when I build a Princeton or Deluxe-style 6v6 amp. I get great low end response on my builds when I use the larger OT iron. I have learned great things from so many on this board, but I don't have the technical chops to understand many things. All I know is I've had great results with this.

[imo1]

What it does is produce the classic "blackface" sound, but is able to hold it together through almost its whole volume range. The clean sound has significantly more low end than a standard Deluxe reverb, which is where I was struggling in the past.

See above, and I'd guess the Fender stack in the clean preamp is giving you the BF sound. That goes away in PAB, though. I will have a look at the curves for the OD stack and compare.
[/quote]

I'd like to elaborate on this a bit more-- I have played so many blackface Fenders in my life, and there are some where the clean sound just sings. In many more modern amps that theoretically employ this same circuit I don't get this same result. I will find the super clean "spanky" sound at low volumes, but the sound quickly falls apart as you get into the middle of the gain range. To me, this is the magic of a great Fender circuit, and is something that is difficult to copy. It actually is what drew me to the Dumble designs, because of any builder, he seemed to hear something similar to this. I love a lot about his clean circuits, but they often sound a little tight to me. I have been trying to find this space--It is the sweet spot between the clean bloom of a really nice blackface, and the more hifi sound of his designs. This seems to be the territory that Two Rock is mining as well.

In any case, this circuit does that. The clean tone totally sings. I found myself often playing completly clean and absolutely loving it for a lead tone. I would use my Kingtone duelist on the "klon" side with the gain on 1 or 2 to get this sound with a slight bit more gain. When i kicked on the OD, the sound wasn't harsh at all(i did back treble and mids below 50%) but absolutely love that sound. It sounds strangely "clean" even though its not. The notes have really good definition and on legato runs, it is the perfect balance between the slur and definition. The low end held together even with the duelist kicked on on top of it!

My only issue was that both the other guys were using bigger amps than mine and I, at time, at a hard time hearing what I was doing. It was nice, for once, not to be too loud!

[martin manning]

I'd like to elaborate on this a bit more--

Imo1, check your PM’s

[imo1]

Thanks for the message Martin! I’m just super jazzed about this amp. I know I sound like a teenager, but it really feels like it does what I need better than any amp I’ve ever played. Now the key is seeing how it scales. I would be interested trying similar build style with a Vibrolux or pro. The pro rvb might be the best since it already has the 2x12. I think a 12” speaker is important for this circuit.