Which 50 watt Dumble should I build ?

[joe6v6]

Several Months ago I built a Trinity ODS kit, I made my own cab & it turned out really nice, very nice clean tone, I Made the mistake of lending it to a good frind of mine who is a working misician & a much better guitar player than I could ever hope to be. Well he wants to buy it and I dont have the heart to say no even though I would like it back. So I have a lot of the parts already & I think I can build one that is even better. The trinity had a dual impedance output transformer to switch between 6v6 & 6L6 tubes which I dont want or need, I have most all of the parts I will need to build a 2x 6L6 ODS - I will probably not include the FET input unless someone can convince me that I need it. . So my question is to those who have built the 2 tube ODS style amps, which Schematic/Layout should I use. One difference that stands out to me between the Trinity schematic & all the other 2x schematics ive looked at is the power supply filtering & the use of a choke. . . . Any help or direction is appriciated - Joe

[pompeiisneaks]

If you really love that amp, you could tell him you'll build the exact same thing for him and charge an additional fee for the time of the build of course.

Or if you're thinking of doing a slightly different amp because that one didn't quite fit the bill, then you should define what you did like and didn't like about the build so the gurus about the different tonalities of the different amps can point you in the right direction.

Any of the amps can easily be made into a two tube output, just choose the two tubes and then an appropriate output transformer that's high quality and fits the bill. If you specify the tube you want to use (6L6, 6V6 etc) then many here could likely give you the exact PT and OT you should use.

~Phil

[Mr. dB]

What type of ODS does the Trinity circuit most closely resemble?

Compared to the Trinity amp, would you prefer the same character, something smoother and more "refined", or something maybe a little rawer and more assertive?

[joe6v6]

The Trinity amp is based on #124 - While I really do like the sound & tone of the clean channel it seemd like a little something is missing from the overdrive , not in the amount of gain but in a musical way. I know some tweaking may have helped but it left me before any real attempts were made. I just asked in another post about the coupling caps- my kit came with 715's & I noticed another builder who has a trinity kit under way has 6PS caps which I guess are the prefered caps to use. I have nothing to compare as to wether those would make a difference. . . As for this next build I already have the Transformers I will be using for a 2x6L6 build. This is the output http://www.classictone.net/40-18011.pdf
& the power trans is a Hammond 290DX 325-325 @ 200ma , I have everything else, including 6ps caps, in my shop. I just really want that singing musical overdrive tone. . Joe

[M Fowler]

I always wanted to build a ODR but haven't yet. That way you get the Dumble overdrive with reverb.

I actually prefer the Two Rock John Mayor Signature Reverb but it doesn't break up so one would need to use pedals for that.

[joe6v6]

So anyone who has built the 2nd or 3rd Gen ODS 50W want to want to let me know how they compare say to a 124? I see plenty of diffrent values thruout & the tonestack is changed. I think the transformers I have will work well in one of these. Also who can chime in on the fet input, does it get used often? I read somewhere that it was originally designed for acoustic guitars. Is it a worthwhile feature in an amp that will be somewhat non traditional & certinly not a clone. Im still trying to decide which way to go. . Tx - Joe

[norburybrook]

Having just built a 50w 2nd gen these are my initial impressions:

It's a bit more 'chimey' black face than say my #102. I built a #124 and didn't like it, i tried classic and skyline EQ and in the end re did it as a #102.

The FET is something I've never put on any builds. This time I decided to use it and put it on a footswitch.

It's fantastic, yes it was originaly designed for Ovation guitars and the like but it's basically a really nice clean boost pedal. So putting on a footswitch is like having a built in Exotic EP booster pedal at your disposal. It's really great for that SRV, crunchy/chimed strat sound and works equally as well with clean and OD.

I like the Jazz voicing on this amp too more than any other Dumble I've built. The bass control really blooms on Jazz setting.

Makes fro a versatile little amp I'd say.

If you're after the 'classic' Robben Ford Dumble ODS then this isn't the amp for you though, it is a great amp however.

It will be interesting to see what speakers will suit it best when I build the combo cabinet. Speakers really do have a huge impact on the sound.

M

[joe6v6]

I am going to build the Ford #102 with 2 x 6L6 - are there any values on the layout or schematic that should change going from 4 power tubes to 2? Or just go with it the way it is.
Im actualy pretty excited now that ive settled on what amp im building, all these variations remind me of picking out a camshaft, so many chioices. . Tx - Joe

[pompeiisneaks]

Switching from 4 to 2 tubes requires two less sockets, a few less resistors, and a different output transformer. You would also need to make sure you have the bias adjustment set for a bit different range so you can cover the different current needs for the tubes I believe as well.

One of the discussions I had with Jelle and others on a facebook thread or a post here (I don't recall which), though, is that 4 tubes has a different tonal characteristic than 2, and often people really prefer the 4 vs 2 sound. The loudness isn't as much as you'd think, going from 50W to 100W is only about a 3db change, so you're not massively impacting the loudness.

~Phil

[norburybrook]

a 100w amp has a fuller bottom end when pushed, however the 50w can be driven harder so that brigs some sonic benefits.

Some people suggest halving the main filtering on a 50w over a 100w but I experimented with this and couldn't really hear a difference. I've built both my #102's with the full 100w filtering and they sound great.

If you have a chassis that's punched for a 100w then I'd build the 100 just so you know what we're talking about and I'd wire in a half power switch from #124, I think it's that one, has an LED on the DPDT switch. That pulls two tubes out of the equation so you'll hear the subtle difference between 50/100w.

It's only about $5 worth of parts to do so why not.

The extra part's cost going to a 100w is not that much, couple of valves/sockets and a different OT.


If you've got the time, try and find an old Peavey 100w amp/combo a deuce or Triumph they have great iron that can be used for a great build, HAD used peavey Iron in some of the ODS builds. You have to change the rectifier to FWBR and perhaps mess with the bias too but If you're lucky you can pick them up cheap, less than the price of new transformers.

just a thought.

M

[martin manning]

I agree with the notion that the 100W will have fuller bass at equal volume. It will cost a few more dollars for larger transformers and 2x output tubes, sockets, screen and grid resistors. Maybe the difference is around $150? The 100W will still sound good turned down using the MV.

If you do a 50W version:
- Bias voltage required will be the same if the plate voltage is the same.
- The feedback network will need some adjustment, basically reduce the FB resistor by 30% to compensate for the reduced output voltage.

[norburybrook]

I agree with the notion that the 100W will have fuller bass at equal volume. It will cost a few more dollars for larger transformers and 2x output tubes, sockets, screen and grid resistors. Maybe the difference is around $150? The 100W will still sound good turned down using the MV.

If you do a 50W version:
- Bias voltage required will be the same if the plate voltage is the same.
- The feedback network will need some adjustment, basically reduce the FB resistor by 30% to compensate for the reduced output voltage.

Interesting. I've never altered the feedback resistor value on either of my 50w builds. Might be something to experiment with.

M

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[joe6v6]

Ive already got the transformers im going to use for the 50W so maybe the 100 will be next time. For the most part I just wanted to confirm using the 102 layout & schematic as they are(-2 tubes) My output trans only has a 4ohm tap, its been laying there for a while wating to be used. . Thanks : Joe

[pompeiisneaks]

a 100w amp has a fuller bottom end when pushed, however the 50w can be driven harder so that brigs some sonic benefits.

Some people suggest halving the main filtering on a 50w over a 100w but I experimented with this and couldn't really hear a difference. I've built both my #102's with the full 100w filtering and they sound great.

If you have a chassis that's punched for a 100w then I'd build the 100 just so you know what we're talking about and I'd wire in a half power switch from #124, I think it's that one, has an LED on the DPDT switch. That pulls two tubes out of the equation so you'll hear the subtle difference between 50/100w.

It's only about $5 worth of parts to do so why not.

The extra part's cost going to a 100w is not that much, couple of valves/sockets and a different OT.


If you've got the time, try and find an old Peavey 100w amp/combo a deuce or Triumph they have great iron that can be used for a great build, HAD used peavey Iron in some of the ODS builds. You have to change the rectifier to FWBR and perhaps mess with the bias too but If you're lucky you can pick them up cheap, less than the price of new transformers.

just a thought.

M

Yes it is the #124, I'm putting it into my build as well. It's a switch, an LED and two 10k resistors and your'e golden. just sends the cathodes through 10k resistance to ground which means the tubes stop conducting, a great way to do it.

~Phil

[joe6v6]

The LNFB switch on this layout- seems to just ground the negative feedback circuit on V1. Is this a good way to do it? Would it be better to put a switch that diconnects it? And lastly what affect does it have on the tone, sound, feel of the amp? . . Sorry , I could not finda a schematic that shows it. thanks : Joe