Help me mod my 102 - it's too bright!

[talbany]

Guy's
The opinion of 102 being a bright amp was not something I brought up because it's just my opinion or how my amps turned out?. Here is a post by Shad. the person who gave us all the specs on 102. He also reversed engineered and was in 183 as well as I imagine a few other Dumbles, so he has some frame of reference. I am just basically repeating what he said.

Trying not to put my own opinion into the mix.... but do have to say that I think without the loop the Ford amp is by far a very bright amp.

https://ampgarage.com/forum/viewtopic.p ... hilit=shad


if i had to guess I would imagine most of the brightness comes from the 68 Pf bright master as well as a Silver mica. So this is where I get the opinion that compared to other amps 102 was known to be a little on the "Bright" side..We already know every amp is different and depending on the part types used as well as many other factors.

Don't shoot the messenger
Tony

Perhaps the new resistors and orange drops are not as bright as the originals? As I said I've built 3 and played 2 others from another forum member and they all sound pretty much the same and none of them are bright amps at all.

I've not used any NOS parts in my #102 builds, I've used various transformers and ceramic caps,but as I said all 5 of them sound pretty much the same . I gave Larry Carlton a choice of my amps and he tried all three I have and chose the #102 I don't think Larry likes a bright sound particularly either.

Anyway, do you think there's something myself and Philly hudson are doing wrong with regard to this?, we both use the #102 layout and schematic in the files section and end up with nice well balanced amps IMHO. I'd be curious to know why

M

I don't know? The only other thing I can tell you is that 102 might have a Polypropylene mid cap?..AFAIK 102's mid caps composition is unknown?..This would definitely make the amp much brighter..I've said in multiple posts here that I think 102 does have a polypropylene mid cap but this is just my opinion??

Everyone has their own opinion on what they consider a "Bright amp" and I have already said why I think 102 is brighter than other ODS amps.(Bright mstr and mica) makes sense to me.

BTW.I don't consider the Q-Lines or MK'3's bright sounding resistors.IMO
Tony

[ijedouglas]

Guy's
The opinion of 102 being a bright amp was not something I brought up because it's just my opinion or how my amps turned out?. Here is a post by Shad. the person who gave us all the specs on 102. He also reversed engineered and was in 183 as well as I imagine a few other Dumbles, so he has some frame of reference. I am just basically repeating what he said.

Trying not to put my own opinion into the mix.... but do have to say that I think without the loop the Ford amp is by far a very bright amp.

https://ampgarage.com/forum/viewtopic.p ... 68#p131868

if i had to guess I would imagine most of the brightness comes from the 68 Pf bright master as well as a Silver mica. So this is where I get the opinion that compared to other amps 102 was known to be a little on the "Bright" side..We already know every amp is different and depending on the part types used as well as many other factors.

Don't shoot the messenger
Tony

Tony, I totally agree with you. I'd like to add, even with the 68pf out of circuit and a ceramic treble cap, mine is still on the bright side (which I am currently really enjoying). I think its coming from the Sprague 715p mid cap I used. I experimented with a 6PS in that position and it took away some of the brightness. I am also using an NOS 715P. I think the original had a blue polypropylene in that position.

Edit: I missed your last post on the mid cap

Ian

[erwin_ve]

repeat; the 68pF on the master does make the amp bright at low setting, cranking the master defies the effect of the bright cap. As simple as that.
IMO it is there to compensate for loss of the cable to and from the dumblelator. Robben plays loud so a bigger bright cap makes sense.

A few yrs ago I was at a gig of Robben playing his #102 without a dumblelator. I came early and saw a part of the soundcheck where Robben asked 2 times: isnt my amp too bright?(!)
After the gig I saw the back of the amp: there was a cable from the send, rolled in the back of the amp, to the return. Probabably to cut the most bright edge off.
I understand from a artistic view that Robben went a different route soundwise but when ditching his dumblelator part of the magic sing disappaered.
The Jing Chi recordings are IMO the highlight of what I consider his best tone.

[PicknStrum]

Guy's
The opinion of 102 being a bright amp was not something I brought up because it's just my opinion or how my amps turned out?. Here is a post by Shad. the person who gave us all the specs on 102. He also reversed engineered and was in 183 as well as I imagine a few other Dumbles, so he has some frame of reference. I am just basically repeating what he said.


https://ampgarage.com/forum/viewtopic.p ... hilit=shad


if i had to guess I would imagine most of the brightness comes from the 68 Pf bright master as well as a Silver mica. So this is where I get the opinion that compared to other amps 102 was known to be a little on the "Bright" side..We already know every amp is different and depending on the part types used as well as many other factors.

Don't shoot the messenger
Tony

Perhaps the new resistors and orange drops are not as bright as the originals? As I said I've built 3 and played 2 others from another forum member and they all sound pretty much the same and none of them are bright amps at all.

I've not used any NOS parts in my #102 builds, I've used various transformers and ceramic caps,but as I said all 5 of them sound pretty much the same . I gave Larry Carlton a choice of my amps and he tried all three I have and chose the #102 I don't think Larry likes a bright sound particularly either.

Anyway, do you think there's something myself and Philly hudson are doing wrong with regard to this?, we both use the #102 layout and schematic in the files section and end up with nice well balanced amps IMHO. I'd be curious to know why

M

I don't know? The only other thing I can tell you is that 102 might have a Polypropylene mid cap?..AFAIK 102's mid caps composition is unknown?..This would definitely make the amp much brighter..I've said in multiple posts here that I think 102 does have a polypropylene mid cap but this is just my opinion??

Everyone has their own opinion on what they consider a "Bright amp" and I have already said why I think 102 is brighter than other ODS amps.(Bright mstr and mica) makes sense to me.

BTW.I don't consider the Q-Lines or MK'3's bright sounding resistors.IMO
Tony

Guy's
The opinion of 102 being a bright amp was not something I brought up because it's just my opinion or how my amps turned out?. Here is a post by Shad. the person who gave us all the specs on 102. He also reversed engineered and was in 183 as well as I imagine a few other Dumbles, so he has some frame of reference. I am just basically repeating what he said.

Trying not to put my own opinion into the mix.... but do have to say that I think without the loop the Ford amp is by far a very bright amp.

https://ampgarage.com/forum/viewtopic.p ... 68#p131868

if i had to guess I would imagine most of the brightness comes from the 68 Pf bright master as well as a Silver mica. So this is where I get the opinion that compared to other amps 102 was known to be a little on the "Bright" side..We already know every amp is different and depending on the part types used as well as many other factors.

Don't shoot the messenger
Tony

Tony, I totally agree with you. I'd like to add, even with the 68pf out of circuit and a ceramic treble cap, mine is still on the bright side (which I am currently really enjoying). I think its coming from the Sprague 715p mid cap I used. I experimented with a 6PS in that position and it took away some of the brightness. I am also using an NOS 715P. I think the original had a blue polypropylene in that position.

Edit: I missed your last post on the mid cap

Ian

I had to go back and check what I used for a mid cap. I have a 6PS there, so in theory I'm cutting a little top end off with that.

[ijedouglas]

I don't think it so much cuts the top end but adds lower mids which gives the perceived effect of less top-end. I think a polypropylene mid cap is part of the sound of this amp... try it and see

[Colossal]

Guy's
The opinion of 102 being a bright amp was not something I brought up because it's just my opinion or how my amps turned out?. Here is a post by Shad. the person who gave us all the specs on 102. He also reversed engineered and was in 183 as well as I imagine a few other Dumbles, so he has some frame of reference. I am just basically repeating what he said.

Trying not to put my own opinion into the mix.... but do have to say that I think without the loop the Ford amp is by far a very bright amp.

https://ampgarage.com/forum/viewtopic.p ... 68#p131868

if i had to guess I would imagine most of the brightness comes from the 68 Pf bright master as well as a Silver mica. So this is where I get the opinion that compared to other amps 102 was known to be a little on the "Bright" side..We already know every amp is different and depending on the part types used as well as many other factors.

Don't shoot the messenger
Tony

Hi Tony,

No bullets intended! I forgot to mention that I omitted the bright cap on the master too! And no silver micas! Also used F&Ts in the power supply. It was bassy amp for sure! Plenty of beef on tap. I will try polypropylene for Midrange on my own build too. Oh, I can see how it might appear brighter with the preamp volume lower. Turn up the preamp volume a bit (and the master at about 3) to get it cooking a little, and man, it is the best hi-fi amp that isn't hi-fi ever. Need to PM you.

[talbany]

I don't think it so much cuts the top end but adds lower mids which gives the perceived effect of less top-end. I think a polypropylene mid cap is part of the sound of this amp... try it and see

Correct! I call it the Silver Mica of Mid caps..Brightens up the mids..If you listen to Robben it's not the highs that are bright it's the Mids. This also helps compensate for the lower knee the high plates have, which can flatten the top end, (along with the NFB). This is IMO how Robben gets away with running his treble pot so low. (no bright switch) on a High Plate amp.

Tony

Ford.jpg

download.jpeg

[talbany]

Guy's
The opinion of 102 being a bright amp was not something I brought up because it's just my opinion or how my amps turned out?. Here is a post by Shad. the person who gave us all the specs on 102. He also reversed engineered and was in 183 as well as I imagine a few other Dumbles, so he has some frame of reference. I am just basically repeating what he said.

Trying not to put my own opinion into the mix.... but do have to say that I think without the loop the Ford amp is by far a very bright amp.

https://ampgarage.com/forum/viewtopic.p ... 68#p131868

if i had to guess I would imagine most of the brightness comes from the 68 Pf bright master as well as a Silver mica. So this is where I get the opinion that compared to other amps 102 was known to be a little on the "Bright" side..We already know every amp is different and depending on the part types used as well as many other factors.

Don't shoot the messenger
Tony

Hi Tony,

No bullets intended! I forgot to mention that I omitted the bright cap on the master too! And no silver micas! Also used F&Ts in the power supply. It was bassy amp for sure! Plenty of beef on tap. I will try polypropylene for Midrange on my own build too. Oh, I can see how it might appear brighter with the preamp volume lower. Turn up the preamp volume a bit (and the master at about 3) to get it cooking a little, and man, it is the best hi-fi amp that isn't hi-fi ever. Need to PM you.

No Bullet was fired back PM away

repeat; the 68pF on the master does make the amp bright at low setting, cranking the master defies the effect of the bright cap. As simple as that.

Yep!

[norburybrook]

I think that's a really good point about the master , I always use my amp fairly loud, so the master bright cap isn't as effective then for me also I'm pretty sure I use a 6ps for the mid everytime. And one other thing, speakers: the G12-65 is a bright speaker, I don't use it with my #102 I prefer the EVM 12 or a classic lead 80 or Alnico cream which are all less peaky than the G12-65.

when I'm comparing 'bright' amps I'd say my Trainwreck, Marshalls are 'bright' amps.


Carry on, good discussion


M

[PicknStrum]

Fairly major breakthrough: changing the trimpots from the small bourns to Piher PT15's had almost as large an effect as removing the master bright cap. I did also change out the 390pF mica to ceramic which also definitely helped. I'm now playing with treble, mid and bass all at noon. Almost feels like I should try and get a little bit of sparkle back I like it so much better on both the clean and dirt channels now.

For reference, here is where I had my treble and middle set for each stage of part-swapping:

No modification: treble and middle completely down

Master Cap removed: treble and middle about 2 to 3.5

Ceramic cap 390pF in place of mica: treble about 4 and middle about 3.5

Piher trimmers in place of Bourns: Treble and middle at noon


I may now experiment with a polypropylene mid cap and or bringing back a little brightness through a lower value master cap as you guys suggested.

Also, I'm still going to try a tantalum for the presence cap. It doesn't really seem like my presence knob is doing anything? Is this a volume thing? I thought I read an old post by Tony that said the presence knob doesn't really come into play until the amp is turned up...

***Pictures to come

[ijedouglas]

Great news!
I think the polypropylene mid cap will get you closer. You may also want to try it both ways (outside foil direction) and see which you prefer. Try that before the master bright.

[PicknStrum]

Great news!
I think the polypropylene mid cap will get you closer. You may also want to try it both ways (outside foil direction) and see which you prefer. Try that before the master bright.

Will do!

[talbany]

Fairly major breakthrough: changing the trimpots from the small bourns to Piher PT15's had almost as large an effect as removing the master bright cap. I did also change out the 390pF mica to ceramic which also definitely helped. I'm now playing with treble, mid and bass all at noon. Almost feels like I should try and get a little bit of sparkle back I like it so much better on both the clean and dirt channels now.

For reference, here is where I had my treble and middle set for each stage of part-swapping:

No modification: treble and middle completely down

Master Cap removed: treble and middle about 2 to 3.5

Ceramic cap 390pF in place of mica: treble about 4 and middle about 3.5

Piher trimmers in place of Bourns: Treble and middle at noon


I may now experiment with a polypropylene mid cap and or bringing back a little brightness through a lower value master cap as you guys suggested.

Also, I'm still going to try a tantalum for the presence cap. It doesn't really seem like my presence knob is doing anything? Is this a volume thing? I thought I read an old post by Tony that said the presence knob doesn't really come into play until the amp is turned up...

***Pictures to come

The presence control doesn't really do much until about 1 o'clock then you should be able to hear something move. Amount of signal (volume) does make a difference. Also install the Tant and see how that does?. Also you can now tweak the Bright master to taste(after the 716) with either mica or a ceramic there. Mica's have a bit more sparkle. As far as the 716 it will brighten up the mids quite a bit. Give it some time and play around with it. It takes a little getting used too and your settings will change. This mod sounds better on a stage with a band and not sitting at home sitting directly in front IMO. Just to give you a heads up. Speakers also matter.

Glad you got it sorted out!
Parts matter
Tony

[Ampnos1]

For guitars, I'm playing strat, tele, and SG in typical pickup configurations - Strat = 3 singles; tele = 2 singles; SG = 2 humbuckers.

Yeah, the Texas Heat was definitely a darker speaker. With the master bright cap gone and the EVM in there, I feel like I'm at a similar brightness to when the Texas Heat was in, but the amp is more jangly and the OD sounds better (both of which I like). I'm definitely keeping the EVM in there. I also love how the EVM sounds with my Princeton.

Thanks for your other recommendations. I'll probably stick with the JJ preamp tubes for now as I'd like to try these other inexpensive mods first. Also, I'm not a huge fan of feedback switches. I have one in a 5E3 and I just never use it.

Interesting to hear your thoughts on the HRM stack. What do you like / dislike about it?

Ian,

I'll have keep listening and try to get an ear for those singing harmonics. Definitely need to develop my ears for a lot of things amp-voicing related.

Your statement regarding the 124 and 183 vs. the 102 has me wondering if perhaps I'd prefer to mod this over to one of them. It's definitely something I'll be thinking about as I'm still going to work through some of the mods Tony suggested first.

Oh, and I'll try to get updated pictures up shortly. So far, all I've really done is clipped the master cap and desoldered then resoldered the 500pF cap. Although it's in there, the leads are shorter than I'd like, so I'll eventually probably throw a whole new 500pf in there.

Thanks for everyone's input.

I ran across this on the forum after trying multiple things to tame the brightness my 102 build and nothing seem to work. I tried this network on the FX send/return jacks and this was the solution for me. It’s worth a try!!

993CF344-27D7-4036-98C7-EC06B001C68F.jpeg

[Audiodog]

My Bludo Ojai is built with NOS parts, selected by a Brandon to mirror what was in Robben’s amp. The only thing that made it bright was the 68pf master bright cap. With long cables and the loopalator, it is not bright. I felt that at my smaller venue gigs, the system worked better with a 27pf bright so I don’t have to run the master as high and I keep the loop in the sweet spot. No need for a bright cap if you don’t run the loop.

102 is not a bright amp. I have modded and tweaked over a dozen amps into this circuit and none are bright. All are sweet, well balanced, and have the sound. Never clip the 500pf across the V2B grid. Ever. That is a crucial part of the tone. I run 250pf snubbers and PS caps, except the mid cap which I believe is a film cap with EM on it. El Meneco I think. A PS works fine here too.

I also extensively have experimented with silver mica treble caps. Brand matters! The brown CDE are actually darker than most ceramics to my ears. A good silver mica is a little smoother than the ceramics. I prefer the yellow silver micas. Not a brightness that needs to be tamed.