#183 questions and possible conclusions

[ElectronAvalanche]

Hi all,

I recently rebuilt one of my HRM with Fender Twin iron to #183 specs and must say I really like it a lot.

I used mdroberts schematic (thanks again for the great work) dating from April 2011. This schematic shows the 25pF snubbers.

I read that there was some dispute over the value of the snubbers in late 2010 fueled by dogears stating that he likes 250pF.

In my experience, the 25pF snubbers really are better suited for the #183, at least in my clone. Has the forum settled on 25pF yet?

Concerning the power section, I listened to the great clips from boldaslove using his Quinn preamp into a BM power section (see youtube) and it seems to me that the characteristics of #183 are really there comparing to the real deal. So this somewhat rules out the influence of the specific Power section of #183 (or Power supply: 330uF caps).

My amp has some nice top end, very musical treble. The amp shines most with a Telecaster or a Les Paul. Not so much with a Stratocaster (using Alnico V small diameter magnets and 5kish pickups I wound myself). Not enough Mids coming from the guitar I guess.

I might go back and try to find a better setting for the OD-trimmer, since this might be a way to get a better OD sound with Strats. For now I have it set at approx. 40k. Maybe going lower is the key.

Has anyone done tests comparing filter caps. I for now have two 220uF in series for B+, I might try 330uF (JJ). Would be very happy to hear any experiences with that . Given that I personally think that the Power Amp does not influence the sound too much.

Thanks again to all parties involved in the #183 schematic/layout.

Cheers,

Electron

[stelligan]

Very interested in this topic as well. My 183 variant has 120pf snubbers, 6L6s, and switchable feedback at V1. I plan to go to 25pf, but the 120s were all that was left in the parts drawer. What are you hearing for the better at 25?

FWIW I am leaving the feedback on at V1 most of the time. The cleans are big and fine.

My guitar preferences with the amp are similar to yours - with my Strats on the bottom, again. I guess that is life with high plate amps?

It sounds very fine as is, but this is to be my final d-style build and a keeper. I'd like to milk all the tone I can from it. Ampdork is likely building those preamps with all those 183 specific parts. That is perhaps getting the tone nailed - along with his skills and time inside 183. Those clips do sound great. And so do clips I've heard direct from that preamp.

Again, very interested in everyone's findings.

[ElectronAvalanche]

Very interested in this topic as well. My 183 variant has 120pf snubbers, 6L6s, and switchable feedback at V1. I plan to go to 25pf, but the 120s were all that was left in the parts drawer. What are you hearing for the better at 25?

FWIW I am leaving the feedback on at V1 most of the time. The cleans are big and fine.

My guitar preferences with the amp are similar to yours - with my Strats on the bottom, again. I guess that is life with high plate amps?

It sounds very fine as is, but this is to be my final d-style build and a keeper. I'd like to milk all the tone I can from it. Ampdork is likely building those preamps with all those 183 specific parts. That is perhaps getting the tone nailed - along with his skills and time inside 183. Those clips do sound great. And so do clips I've heard direct from that preamp.

Again, very interested in everyone's findings.

Hi Stelligan,

IMHO (YMMV) the 25pFs do not constrict the sound as much as the higher value snubber in the high mid range. There seems to be more of that nice top high end that makes for the Dumble sound.

I think this sound comes out most pronounced when moving up/down (glissando) some notes on the wound strings.

Very hard to describe... the top high frequencies seem to distort differently than all other freqs. Giving a sometimes "dry papery sound" in these freqs.

The same applies to the SSS IMHO,just that it seems that all freqs are non-distorted and only the topmost high freqs (maybe higher than 3k, harmonics up to 5k? or even higher?) seem to distort very musically.

I too have the V1 LNFB switchable and have yet to decide what I like best with the Strat. Wit LP it is clearly 22M -> 0.047, with Tele its 44M -> 0.047.

What do you mean by 183 specific parts? NOS? What tubes does he ship this preamp with?

I need to try short-plate 12AX7 (GE) in my amp (if I do find any), but the EH sound quite nice to my ears.

My next amp will be a 100k 70s circuit. When I started in 2000 I built a preamp that had both 220k/150k Skyliner and separate from that 100k. I used all WIMA MKS caps back then and I remember that the sound of the 220k section was very nice.

Unfortunately I ripped apart the preamp in 2003

Cheers,

Electron

[stelligan]

What do you mean by 183 specific parts? NOS? What tubes does he ship this preamp with?

I need to try short-plate 12AX7 (GE) in my amp (if I do find any), but the EH sound quite nice to my ears.

I thought that amp was full of Sprague Q-lines and Mepco blue metal films. see here:
https://tubeamparchive.com/viewtopic.ph ... &start=105

Dunno what Shad is putting in those preamps, but I would imagine they are the Q-lines. I tried a GE short plate in mine and it did not wow me over the EHs.

[ElectronAvalanche]

What do you mean by 183 specific parts? NOS? What tubes does he ship this preamp with?

I need to try short-plate 12AX7 (GE) in my amp (if I do find any), but the EH sound quite nice to my ears.

I thought that amp was full of Sprague Q-lines and Mepco blue metal films. see here:
https://tubeamparchive.com/viewtopic.ph ... &start=105

Dunno what Shad is putting in those preamps, but I would imagine they are the Q-lines. I tried a GE short plate in mine and it did not wow me over the EHs.

I have some 100k Q-Lines that I found years ago in a surplus store. I was not able to discriminate between them and Draloric Carbon Film.

For my 183 clone I used all Vishay Metal Film for the plates (from 2001), Draloric CF for cathodes and Draloric/Sprague (100k) Q-Line.

In my other amps I used some green metal films (maker unknown) and these were extremely cheap but sound very nice. Nicer than Dales btw.

I think more important than maker (given they are the same material) are the exact values. I would think that Dumble would rather look for consistency value-wise than for maker. In an interview he said that he had about 30% rejects with his parts.

OTOH if all resistors of different makers/brands you use are 1% tolerance I think that would not make too much of a difference.

Would be interesting to know what type of resistors / caps Dumble uses (would use) now. What is the latest ODS we know of, and what brands (Xicon resistors?) of resistors did he use for it?

Cheers,

Electron

[ToneMerc]

I thought that amp was full of Sprague Q-lines and Mepco blue metal films. see here:
https://tubeamparchive.com/viewtopic.ph ... &start=105

Dunno what Shad is putting in those preamps, but I would imagine they are the Q-lines. I tried a GE short plate in mine and it did not wow me over the EHs.

Those large pretty blue resistors aren't Mepco/Electra; they were actually made by Corning. They have two types of surface finishes, the oldest versions have the smooth glass like finish.
My hole in wall local source still has some of these and they were rebranded as NTE, RCA and Sylvania. I also found a pack Sprague Q Lines the other week and I'm now pretty certain who actually made the Sprague Q lines as well.

TM

[dogears]

I used 68pf on my last build. My first "clone" has the 25pf as instructed by Shad. I liked the 250pf when I had a 100K level pot. 250K darkened and fattened it up so the 25pf worked perfectly at that point.

The 68pf is in my original Glaswerks SOD which I messed with this weekend. It switches between a quasi 183 voice and an HRM voice with a modded OD network.

I had a bag of 68pf handy.... I think anything under 150pf is moot.

[jestaudio]

all this talk of varying values for snubbers has made me check my new ceriatone based build and there are no snubbers on V2, the amp sonically sounds good but now i,m wondering what sort of difference adding snubbers might make?

[ampdork]

Greg preamp has some nos caps...

The actual 183 has mostly NTE flame proofs with occasional piher/beyshclag/q lines in other places...mostly signal path/grids and in the PS..

I probably use the fancy big resistors in the signal only...cathodes, plates and others use the nte flame proofs or whatever your favorite MF is..

Having messed with NOS a bit I find the caps have some "mojo" going.
I really do seem to like the paper and foil caps.
The resistor much less so.

Agree with TM....Value is king.

Pictures were labeled wrong. Those four hole vented resistor are indeed re branded NTE. I like them for certain things and wish I had more values and a new production source.
Some mepcos/electras in this picture...

[img1944]http://img176.imageshack.us/img176/4019/dsc01218w.jpg[/img]

I "think" Tony's layout show most of the resistor brands....maybe coded by color? I forget but there is some of that info on the layout I think...

I am really glad that so many have built 183's and seem to like them.
I find it is one of my favorite Dumble amp circuits.

If doing a 6l6 version Stelligan has the right idea imho... With the 6l6 I find the easiest way to tweak it into shape is the snubber and LNFB on v1... That worked best for me anyway. I thought the 6l6 version was a bit boomy out of the box....all subjective stuff though..

Keep building and try to think kindly of old man Dumble. :O)

[ampdork]

No snubbers eh?

I wonder what other liberties have been taken? Got any pics?

[jestaudio]

No snubbers eh?

I wonder what other liberties have been taken? Got any pics?

Will get some posted shotly but as far as i can see most of the preamp valus are similar, no fet circuit which in fairness doesnt bother me , the bright switch is on a push pull and a deep switch sits in place

[jestaudio]

No snubbers eh?

I wonder what other liberties have been taken? Got any pics?

Will get some posted shotly but as far as i can see most of the preamp valus are similar, no fet circuit which in fairness doesnt bother me , the bright switch is on a push pull and a deep switch sits in place

Gut shot of V1 and 2

[talbany]

I used 68pf on my last build. My first "clone" has the 25pf as instructed by Shad. I liked the 250pf when I had a 100K level pot. 250K darkened and fattened it up so the 25pf worked perfectly at that point.

The 68pf is in my original Glaswerks SOD which I messed with this weekend. It switches between a quasi 183 voice and an HRM voice with a modded OD network.

I had a bag of 68pf handy.... I think anything under 150pf is moot.

I agree..All my personal amps have 250k level in them and found no such need for snubbers..

IMO the NOS Sprague caps are a bit smoother darker and sweeter sounding than the new 6PS's but not really anything to rave about..you can still build a sweet sounding ODS using the new 6Ps's..Resistors are another story..IMO of coarse..


Tony

[ToneMerc]

Greg preamp has some nos caps...

The actual 183 has mostly NTE flame proofs with occasional piher/beyshclag/q lines in other places...mostly signal path/grids and in the PS..

I probably use the fancy big resistors in the signal only...cathodes, plates and others use the nte flame proofs or whatever your favorite MF is..

Having messed with NOS a bit I find the caps have some "mojo" going.
I really do seem to like the paper and foil caps.
The resistor much less so.

Agree with TM....Value is king.

Pictures were labeled wrong. Those four hole vented resistor are indeed re branded NTE. I like them for certain things and wish I had more values and a new production source.

I "think" Tony's layout show most of the resistor brands....maybe coded by color? I forget but there is some of that info on the layout I think...


Keep building and try to think kindly of old man Dumble. :O)

RCA branded "blue resistors" and some 80's vintage Q lines, old enough that the plastic has turned amber and cracked.

I'm going to do my #183 without the big filters as well.

TM

[Mr Dumble]

Greg preamp has some nos caps...

The actual 183 has mostly NTE flame proofs with occasional piher/beyshclag/q lines in other places...mostly signal path/grids and in the PS..

I probably use the fancy big resistors in the signal only...cathodes, plates and others use the nte flame proofs or whatever your favorite MF is..

Having messed with NOS a bit I find the caps have some "mojo" going.
I really do seem to like the paper and foil caps.
The resistor much less so.

Agree with TM....Value is king.

Pictures were labeled wrong. Those four hole vented resistor are indeed re branded NTE. I like them for certain things and wish I had more values and a new production source.
Some mepcos/electras in this picture...

[img1944]http://img176.imageshack.us/img176/4019/dsc01218w.jpg[/img]

I "think" Tony's layout show most of the resistor brands....maybe coded by color? I forget but there is some of that info on the layout I think...

I am really glad that so many have built 183's and seem to like them.
I find it is one of my favorite Dumble amp circuits.

If doing a 6l6 version Stelligan has the right idea imho... With the 6l6 I find the easiest way to tweak it into shape is the snubber and LNFB on v1... That worked best for me anyway. I thought the 6l6 version was a bit boomy out of the box....all subjective stuff though..

Keep building and try to think kindly of old man Dumble. :O)

Listen to this guy, he knows 183. My Quinn EL34 TKT has completely cured my "had to sell the Dumble depression". It is every bit as good as my Dumble was. The 6L6 version has more bottom, but for me, is not boomy. (I use G12h30s almost exclusively now, which may be part of that.) Surprsingly, the 6l6 is more compressed, and has less of the "acoustic guitar" sound mixed in with the overdrive that the real 183 and my TKT El34 has so much of. I actually like the cleans more on the El34, which is similar to my my findings at Ultrasound with the three Dumble 6L6s and the one EL34. In any case, those who have an EL34, IMO its worth messing around with a 6L6 power supply, becauise it really is like having a different amp. The 6L6 is very Emerald pro like, but still better in everyway. Amazing amps. Thank you Shad.