Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: SnickSound on February 27, 2019, 06:05:24 am
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Was looking at those 5$ each blue caps from Sozo and it made me wonder: what upgrades are actually worth it?
I've built amps where I went all out, but also other from cheap surplus store parts, and after some tweaking of the circuit they all ended up fine (unless the output transformer was a 125-series).
But maybe I'm missing out on some extra mojo.
What "upgrades" have you found worth the extra cost?
I do know that for a higher gainer (SLO-level of gain), a big metal film resistor on the first plate takes the hiss down noticeably. After that though, it hardly seems to matter.
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Sounds like the tranny is. I would be interested in knowing what readily available tranny do you upgrade to for 125 Series. Sorry I hope I didn't hijack and it ends up being all about trannies.
Hahaha, no problem.
Depends how/why you were using a 125-series. Typically they are coupled with 1-2W dual triode power amps, and there aren't a lot of options for that. I really wish Hammond would release something based on the Marshall 1Watters.
Magnetic Component does make one with a fixed 25k primary impedance, but I have no experience with it so I can't comment. I can't find specs either to see if inductance is significantly improved over a comparable 125C.
But where I did do a comparison was when I was running a pair of 6K6GTs. I found that around 8-9K is where I liked them but like all circuits I've built with a 125-series, it was harsh and lacked bass. So I put a 38$ Hammond 1750PA in its place (18W OT), and that helped a lot. It did not dramatically change the character of the amp, but the harshness was replaced with nice complex mids and a round low-end.
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Was looking at those 5$ each blue caps from Sozo and it made me wonder: what upgrades are actually worth it?
I've built amps where I went all out, but also other from cheap surplus store parts, and after some tweaking of the circuit they all ended up fine (unless the output transformer was a 125-series).
But maybe I'm missing out on some extra mojo.
What "upgrades" have you found worth the extra cost?
I do know that for a higher gainer (SLO-level of gain), a big metal film resistor on the first plate takes the hiss down noticeably. After that though, it hardly seems to matter.
dude you're poking hornet's nest :laugh: :laugh:
nevertheless, IMHO tranny and speakers have most impact on sound :dontknow:
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Caps in the signal path.
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Output transformer, speaker and caps.
I don't think of this in terms of "upgrading" and adding expense but more in that I will go to the trouble to select specific OT, speakers and caps that I know will help towards the tone I want.
With respect, Tubenit
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Caps in the signal path.
"Technically", all caps are in the signal path (baring relay or filament power supply of course)
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For once, I wasn't being technical. :icon_biggrin:
However, do feel free to upgrade them all. It is doable to replace all electrolytic filter & cathode bypass caps, e.g., with plastic. Though that is not what I was suggesting. However I do like to use small value cathode bypass caps like 1uF in preamp stages; and do use use plastic for that.
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You're scaring me. I'm about to do a Hoso + effects 6bm8 build with a Hammond 125E.
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The speaker is worth the upgrade.
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You're scaring me. I'm about to do a Hoso + effects 6bm8 build with a Hammond 125E.
Hahaha, it's not the end of the world, it's just not a great OT. It's only rated down to 125Hz after all.
I'm unfamiliar with the 6BM8. What primary impedance and power level are you going for?
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dude you're poking hornet's nest :laugh: :laugh:
nevertheless, IMHO tranny and speakers have most impact on sound :dontknow:
Speaker (and cabinet) is a definitive yes indeed. An amp is after all just a big power supply feeding a speaker, what you're hearing is that speaker.
But also, a good tuner (is it just me or are DIY amp demos on Youtube always suffering from really badly tuned guitars?)
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On my HoSo56 "the Minimalist" with 6BM8 tubes, I used a Deluxe 5E3 type OT.
Tubenit
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On my HoSo56 "the Minimalist" with 6BM8 tubes, I used a Deluxe 5E3 type OT.
Tubenit
That's a good option
In Hammond-land, a 1750E/1760E (depending on if you want multi-secondaries) would be a nice option at 8.5K
The 1750Z has a 10K primary if required (but single 8 ohm secondary)
If one desires something around 12K, then you can always mismatch a 6K OT (e.g. 8 ohm speaker into 4 ohm tap)
Now, some might argue that these will be too big and won't saturate. But trying to get OT saturation in single-digit power amp is part of why they often end up sounding "small".