SKYLINER build - inspired by ODS #124 and #060

[ijedouglas]

I just think the 110k Rp / 5k (trimmer) / 120k Rp, in the #124 is just a bit sterile for me. I don't know if changing these to the 183 values (100k/10k/110k) will boost the gain any noticably as you seem to suggest it is the cathode resistor which has more impact here, but if I can get that ~7V imbalance in the plates, I'm sure I can call up the second harmonics and access that elusive bloom. There is already a complexity to the note and it sustains well with clear upper partials emerging after the fundamental has decayed - I just feel this amp has more to offer and I just have to find it.

What do you mean by "sterile"? Are you looking for more gain/grit/dynamics/bloom?

[talbany]

This suggests a very "edgy" tone.

I am not sure that i would classify it as "Edgy" To be a bit more specific (again) is loose, more compressed (less punchy) more gain (Harmonic content) or livelier at lower volumes and sustains longer. This is generally a good thing when it comes to the clean channel, However in the OD side can get too compressed and too aggressive sounding (Saw toothed) less smooth and more of a Rock sound. (Like a gainy Marshall with a lot of low end ) So if this is something you want?.. BTW. I would not consider it a sterile sound!.

My 2nd generation PI comment was kind of tongue and cheek, apples to oranges comparison. You can take it seriously and start mixing and matching different PI,s but result will be something completely different than the clips you posted, I think you know why.
If your 124 sounds a little sterile and lifeless I would start by tweaking the GNFB in that amp first see if I can't loosen it up that way. As far as the electrical properties of the the resistors in the PI goes?, I would not worry about it. I would choose the type resistor that sounds best for my style and leave the rest in the rabbit hole.

BTW.. If it sounds a bit sterile to you I recommend trying C.F on the plates and grids first see if you like that along with the GNFB tweak. Report back then. The balance is another can of worms.

Good luck!

Tony

[Stephen1966]

"Loosen it up," "sterile," - stiff... yeah. Regarding the second generation thread, I think you might be overestimating my intelligence on these matters, Tony! I mean, it's an interesting comparison but so much of Ben's sound is in his playing... I worked through the 3rd generation schematic which I understand is close to your 2nd gen layout, and there are a lot more design changes there, than I would care to attempt with my amp, GNFB, power section and so on... I think we all appreciate how you elaborated on this though.

The notes I'm finding are beautiful and complex, I'm sure a Jazz musician would love it. I'm just looking for something a bit more... unrestrained, and definitely more bloom. Marshall-esque? Maybe not, but... Because even if I hammer it with the volume at stadium levels the amp kind of just sits there like a forlorn Fender. The notes just don't reach out and grab you, the fundamental doesn't swell, at least not very much, and not in the effortless way the amps in the clips do.

I'm putting together a shopping list now, so thank you for the heads up. I'm not too interested in going all the way down that rabbit hole, I'm just being nosy: I want to know what's going on I don't have any reservations about using CFs in this part of the signal chain, but I'm ordering MFs as well. For both Bluesmaster and #183 style PI's. IIRC, the early incarnation of the #124 was more akin to the #183. The components are cheap enough and the swap on these boards is easy enough. Worth a try.

[ijedouglas]

Can you post a current gut shot (or is there a link to it)?

[Stephen1966]

Can you post a current gut shot (or is there a link to it)?

Sure! These are older gut shots, some before the heater wiring went in, but nothing has changed yet. Let me know if there is anything you would like a better look at. It's lying naked and afraid on a bench in my basement at the moment, it wouldn't take ten minutes to take a new shot.

SAM_7574.JPG

SAM_7736.JPG

SAM_7667.JPG

[Richard1001]

"Loosen it up," "sterile," - stiff... yeah. Regarding the second generation thread, I think you might be overestimating my intelligence on these matters, Tony! I mean, it's an interesting comparison but so much of Ben's sound is in his playing... I worked through the 3rd generation schematic which I understand is close to your 2nd gen layout, and there are a lot more design changes there, than I would care to attempt with my amp, GNFB, power section and so on... I think we all appreciate how you elaborated on this though.

The notes I'm finding are beautiful and complex, I'm sure a Jazz musician would love it. I'm just looking for something a bit more... unrestrained, and definitely more bloom. Marshall-esque? Maybe not, but... Because even if I hammer it with the volume at stadium levels the amp kind of just sits there like a forlorn Fender. The notes just don't reach out and grab you, the fundamental doesn't swell, at least not very much, and not in the effortless way the amps in the clips do.

I'm putting together a shopping list now, so thank you for the heads up. I'm not too interested in going all the way down that rabbit hole, I'm just being nosy: I want to know what's going on I don't have any reservations about using CFs in this part of the signal chain, but I'm ordering MFs as well. For both Bluesmaster and #183 style PI's. IIRC, the early incarnation of the #124 was more akin to the #183. The components are cheap enough and the swap on these boards is easy enough. Worth a try.

I think you could be focusing to much on the PI for the sound and ' blooming' (or whatever) you are looking for.

For instance: what is your purpose when you put 1000pF caps over the powertubes anodes to ground? Why did you do that and how does it help you to get the sound you are after?

[ijedouglas]

Are you lacking "something" in the OD or both the clean and OD?

I haven't built a BluesMaster yet (it's in the part collection phase) but from what I understand, it may be more of what you are looking for. My 183 definitely has a more aggressive feel to it but my 124 is not too far behind it.

If you like the cleans, you may want to play around with resistor types in OD1/2 entrance as well as the OD trimmer (do you have a 100K or something larger/closer to 124?) before ripping out the PI.

I would also try playing with values in the GNFB as well as disconnecting the LNFB (ala 183) as see what it does.

[Stephen1966]

"Loosen it up," "sterile," - stiff... yeah. Regarding the second generation thread, I think you might be overestimating my intelligence on these matters, Tony! I mean, it's an interesting comparison but so much of Ben's sound is in his playing... I worked through the 3rd generation schematic which I understand is close to your 2nd gen layout, and there are a lot more design changes there, than I would care to attempt with my amp, GNFB, power section and so on... I think we all appreciate how you elaborated on this though.

The notes I'm finding are beautiful and complex, I'm sure a Jazz musician would love it. I'm just looking for something a bit more... unrestrained, and definitely more bloom. Marshall-esque? Maybe not, but... Because even if I hammer it with the volume at stadium levels the amp kind of just sits there like a forlorn Fender. The notes just don't reach out and grab you, the fundamental doesn't swell, at least not very much, and not in the effortless way the amps in the clips do.

I'm putting together a shopping list now, so thank you for the heads up. I'm not too interested in going all the way down that rabbit hole, I'm just being nosy: I want to know what's going on I don't have any reservations about using CFs in this part of the signal chain, but I'm ordering MFs as well. For both Bluesmaster and #183 style PI's. IIRC, the early incarnation of the #124 was more akin to the #183. The components are cheap enough and the swap on these boards is easy enough. Worth a try.

I think you could be focusing to much on the PI for the sound and ' blooming' (or whatever) you are looking for.

For instance: what is your purpose when you put 1000pF caps over the powertubes anodes to ground? Why did you do that and how does it help you to get the sound you are after?

I think you may be referring to the surge protection in this post: https://ampgarage.com/forum/viewtopic.p ... 71#p433271. That mod, which includes a flyback diode as well, which came later, didn't appear to make any difference. I expected it might stifle the high frequency response, but if it has, it hasn't done it in any way I could tell the difference. Before or after...

[Stephen1966]

Are you lacking "something" in the OD or both the clean and OD?

I haven't built a BluesMaster yet (it's in the part collection phase) but from what I understand, it may be more of what you are looking for. My 183 definitely has a more aggressive feel to it but my 124 is not too far behind it.

If you like the cleans, you may want to play around with resistor types in OD1/2 entrance as well as the OD trimmer (do you have a 100K or something larger/closer to 124?) before ripping out the PI.

I would also try playing with values in the GNFB as well as disconnecting the LNFB (ala 183) as see what it does.

It's actually the cleans which are bugging me more than the OD, I like the growl I get from the OD and as long as its not set too high, I get good note definition in power chords there.

The Bluesmaster - if we include the presence pot as well - has a NFB total resistance of close to 130k, the 183 and 124 is about 7k though in the 183 schematic I'm looking at the NFB is tapped off the 8ohm lead - I think that might be a mistake, Tony's layout shows it tapped off the 4ohm lead.
https://tubeamparchive.com/viewtopic.php?f=5&t=13095

I was lifting the NFB earlier last week to double check I had the OT wired up correctly - I didn't think to run a sound check then. Honestly, it's a bit of an ordeal to solder and unsolder but I could put a switch on the bottom of the chassis for it. I'd rather not dispense with it completely.

How would you go about testing the NFB values?

[talbany]

"Loosen it up," "sterile," - stiff... yeah. Regarding the second generation thread, I think you might be overestimating my intelligence on these matters, Tony! I mean, it's an interesting comparison but so much of Ben's sound is in his playing... I worked through the 3rd generation schematic which I understand is close to your 2nd gen layout, and there are a lot more design changes there, than I would care to attempt with my amp, GNFB, power section and so on... I think we all appreciate how you elaborated on this though.

The notes I'm finding are beautiful and complex, I'm sure a Jazz musician would love it. I'm just looking for something a bit more... unrestrained, and definitely more bloom. Marshall-esque? Maybe not, but... Because even if I hammer it with the volume at stadium levels the amp kind of just sits there like a forlorn Fender. The notes just don't reach out and grab you, the fundamental doesn't swell, at least not very much, and not in the effortless way the amps in the clips do.

I'm putting together a shopping list now, so thank you for the heads up. I'm not too interested in going all the way down that rabbit hole, I'm just being nosy: I want to know what's going on I don't have any reservations about using CFs in this part of the signal chain, but I'm ordering MFs as well. For both Bluesmaster and #183 style PI's. IIRC, the early incarnation of the #124 was more akin to the #183. The components are cheap enough and the swap on these boards is easy enough. Worth a try.

Steven
So I think there were a few things that were either mistranslated or misinterpreted!

The comment about the 2nd Generation/Bluesmaster in my 1st post was to simply illustrate some of the different sound characteristics of each of the PI's used in the ODS model amplifiers inherent to the design and not the parts!, since that's what I thought you were asking about (Phase inverters) So to avoid any misunderstandings here! When I talk about resistor types/brands I am talking about nuances or small changes in sound and not the things you described in the your last post to me (unrefined, Bloom). This is clearly something else going on with the amp and I don't think your cure is in your resistor types. Sorry for any confusion!
BTW..Your amp will be even more complex to diagnose here because it is a one of a kind and you didn't follow the layouts in the files section, hopefully you can get squared away!

Tony

[Richard1001]

"Loosen it up," "sterile," - stiff... yeah. Regarding the second generation thread, I think you might be overestimating my intelligence on these matters, Tony! I mean, it's an interesting comparison but so much of Ben's sound is in his playing... I worked through the 3rd generation schematic which I understand is close to your 2nd gen layout, and there are a lot more design changes there, than I would care to attempt with my amp, GNFB, power section and so on... I think we all appreciate how you elaborated on this though.

The notes I'm finding are beautiful and complex, I'm sure a Jazz musician would love it. I'm just looking for something a bit more... unrestrained, and definitely more bloom. Marshall-esque? Maybe not, but... Because even if I hammer it with the volume at stadium levels the amp kind of just sits there like a forlorn Fender. The notes just don't reach out and grab you, the fundamental doesn't swell, at least not very much, and not in the effortless way the amps in the clips do.

I'm putting together a shopping list now, so thank you for the heads up. I'm not too interested in going all the way down that rabbit hole, I'm just being nosy: I want to know what's going on I don't have any reservations about using CFs in this part of the signal chain, but I'm ordering MFs as well. For both Bluesmaster and #183 style PI's. IIRC, the early incarnation of the #124 was more akin to the #183. The components are cheap enough and the swap on these boards is easy enough. Worth a try.

I think you could be focusing to much on the PI for the sound and ' blooming' (or whatever) you are looking for.

For instance: what is your purpose when you put 1000pF caps over the powertubes anodes to ground? Why did you do that and how does it help you to get the sound you are after?

I think you may be referring to the surge protection in this post: https://ampgarage.com/forum/viewtopic.p ... 71#p433271. That mod, which includes a flyback diode as well, which came later, didn't appear to make any difference. I expected it might stifle the high frequency response, but if it has, it hasn't done it in any way I could tell the difference. Before or after...

I ment to use this example to say all details matter for the sound you're after. Not hearing something does not mean it doesn't do anything. What your actualy saying is that you put these two caps in without knowing why exactly, right?

[Stephen1966]

I think you could be focusing to much on the PI for the sound and ' blooming' (or whatever) you are looking for.

For instance: what is your purpose when you put 1000pF caps over the powertubes anodes to ground? Why did you do that and how does it help you to get the sound you are after?

I think you may be referring to the surge protection in this post: https://ampgarage.com/forum/viewtopic.p ... 71#p433271. That mod, which includes a flyback diode as well, which came later, didn't appear to make any difference. I expected it might stifle the high frequency response, but if it has, it hasn't done it in any way I could tell the difference. Before or after...

I ment to use this example to say all details matter for the sound you're after. Not hearing something does not mean it doesn't do anything. What your actualy saying is that you put these two caps in without knowing why exactly, right?

Well, I won't dispute that I could be overlooking something but I had a conversation about this earlier in the topic https://ampgarage.com/forum/viewtopic.p ... 02#p432702 to summarise:
Me: "My best guess on the cap to ground... low capacitance high frequency rejection during spikes/low impedance bypassing for lower frequencies."
Bepone: "it is to reduce some highs..it is limiting tranformer bandwith. it is ok on some present amps.. also 1nF 10kV across the whole primary is ok too"
And there's a bunch of posts then where we go into the issue of transformer return loss as well. Replacing them with 500pF caps or smaller, might be part of the answer. What do you think?

[ijedouglas]

It's actually the cleans which are bugging me more than the OD, I like the growl I get from the OD and as long as its not set too high, I get good note definition in power chords there.

The Bluesmaster - if we include the presence pot as well - has a NFB total resistance of close to 130k, the 183 and 124 is about 7k though in the 183 schematic I'm looking at the NFB is tapped off the 8ohm lead - I think that might be a mistake, Tony's layout shows it tapped off the 4ohm lead.
https://tubeamparchive.com/viewtopic.php?f=5&t=13095

I was lifting the NFB earlier last week to double check I had the OT wired up correctly - I didn't think to run a sound check then. Honestly, it's a bit of an ordeal to solder and unsolder but I could put a switch on the bottom of the chassis for it. I'd rather not dispense with it completely.

How would you go about testing the NFB values?

I'm pretty sure the GNFB is on the 4 Ohm tap.

To test the GNFB, you can either replace the resistor with a 5K pot or just swap out values, should be pretty simple.

To test the LNFB, just lift one of the 10M resistor legs.. or put it on a switch.

The other thing I would highly recommend, is to let the amp settle and break-in a little. Give it 100 hours and see if it is still not to your liking.

[talbany]

The Bluesmaster - if we include the presence pot as well - has a NFB total resistance of close to 130k, the 183 and 124 is about 7k though in the 183 schematic I'm looking at the NFB is tapped off the 8ohm lead - I think that might be a mistake, Tony's layout shows it tapped off the 4ohm lead.

The layout is correct 183 used the 4 ohm tap not 8 ohm. (Less GNFB)
On twin iron he used 8 ohm tap
BTW..An easy way to check GNFB is to take a 10k 15k pot wired as a variable resistor one lead to the NFB resistor and the other to the tap. You can then adjust the pot to the setting that works best then measure the pot value and replace the GNFB resistor to that value.Just make sure your presence control still works with that value.
Tony

[ijedouglas]

The layout is correct 183 used the 4 ohm tap not 8 ohm. (Less GNFB)
On twin iron he used 8 ohm tap

Tony

Isn't the twin also 4 Ohm?