New 183 build

[Stephen1966]

LOL. Well, furthering this tangent along it's smooth trajectory...
... this is where the sheep dung really shines. The taste is quite astringent, as notes of cloves combine with a lingering ashy aftertaste. Memorable!"

There, I ruined the thread!

Hey! Don't sweat it It's only because my soldering station died over Christmas that I haven't been posting amp goodies, but it will be returning soon I promise you.

I'd be a bit leary of sheepshit-inspired-whisky but it's a nice antidote to the whisky-inspired-bullshit found elsewhere

[ViperDoc]

Hey! Don't sweat it It's only because my soldering station died over Christmas that I haven't been posting amp goodies, but it will be returning soon I promise you.

I'd be a bit leary of sheepshit-inspired-whisky but it's a nice antidote to the whisky-inspired-bullshit found elsewhere

Agreed, and great to hear it. I'm very interested in the 183 and looking forward to more progress shots. I just completed a 50W P2P #124 without OD, an affront to convention in all respects, but it sounds great. Onward and upward!

[Stephen1966]

Hey! Don't sweat it It's only because my soldering station died over Christmas that I haven't been posting amp goodies, but it will be returning soon I promise you.

I'd be a bit leary of sheepshit-inspired-whisky but it's a nice antidote to the whisky-inspired-bullshit found elsewhere

Agreed, and great to hear it. I'm very interested in the 183 and looking forward to more progress shots. I just completed a 50W P2P #124 without OD, an affront to convention in all respects, but it sounds great. Onward and upward!

That's interesting... 4 tubes! I imagine it will make a neat little combo. Did you use the Skyline tonestack? It's approaching a Tweedle-Dee, I wonder does it break up in the same way at higher volumes?

[ViperDoc]

That's interesting... 4 tubes! I imagine it will make a neat little combo. Did you use the Skyline tonestack? It's approaching a Tweedle-Dee, I wonder does it break up in the same way at higher volumes?

Yes, it's a Low Plate Skyliner build. It is incredibly clean generally but definitely breaks up nicely when pushed. I used Merc Mag iron and tried to get as many of the right corks in the right bottles, although particulars in the wild are difficult to find these days, I understand. The amp sounds awesome, although I do have Beyschlag MF on the P.I. plates. I might switch out to Kiwame CF if I can find them (124 calls for CF on PI plates). It sounds great as is, though. It can get into legendary rock territory, especially with the PAB and the MID boost paired up. I'm still exploring it.

[Stephen1966]

That's interesting... 4 tubes! I imagine it will make a neat little combo. Did you use the Skyline tonestack? It's approaching a Tweedle-Dee, I wonder does it break up in the same way at higher volumes?

Yes, it's a Low Plate Skyliner build. It is incredibly clean generally but definitely breaks up nicely when pushed. I used Merc Mag iron and tried to get as many of the right corks in the right bottles, although particulars in the wild are difficult to find these days, I understand. The amp sounds awesome, although I do have Beyschlag MF on the P.I. plates. I might switch out to Kiwame CF if I can find them (124 calls for CF on PI plates). It sounds great as is, though. It can get into legendary rock territory, especially with the PAB and the MID boost paired up. I'm still exploring it.

I think I might have posted this link up already, but here is where I get mine from: https://www.hificollective.co.uk/index. ... iwame.html

[ViperDoc]

I think I might have posted this link up already, but here is where I get mine from: https://www.hificollective.co.uk/index. ... iwame.html

You're the second person to recommend that place. Thanks, I appreciate it. Now I know where those pink resistors come from!

[rccolgan]

A little secret, I'm 99% sure that the Kiwame resistors are SPR series Koa Speer (or the other way around?) These guys agree too: http://beezar.com/pho-bzr/catalog/produ ... cts_id=135

https://www.mouser.com/c/passive-compon ... series=SPR

I plan on using them a lot more in future builds. They sound fantastic!

-Ryan

[Guy77]

A little secret, I'm 99% sure that the Kiwame resistors are SPR series Koa Speer (or the other way around?) These guys agree too: http://beezar.com/pho-bzr/catalog/produ ... cts_id=135

https://www.mouser.com/c/passive-compon ... series=SPR

I plan on using them a lot more in future builds. They sound fantastic!

-Ryan

I have been using those resistors lately and I like them a lot too!

Cheers
Guy

[Stephen1966]

Trouble with the Kiwame 2W (or KOAs) is that the 100k/110k needed for the PI are no longer being manufactured. Mouser available KOA SPR2s are all under these values and HiFi Collective has an incomplete inventory of the out of production higher values. I'm trying the AMTRANS in the OD out positions (the 183 is using Xicon MF on its PI plates). Instead of the Kiwame you might try the Xicon CF 1W which are freely available, or if you want to go the extra mile for the #124, you might try to get hold of the Dralorics (0414 type I believe) used in the original. I haven't checked the For Trade or Sale section recently but I believe Jelle Welagen had some of those.

[jazzbass]

A little secret, I'm 99% sure that the Kiwame resistors are SPR series Koa Speer (or the other way around?) These guys agree too: http://beezar.com/pho-bzr/catalog/produ ... cts_id=135

https://www.mouser.com/c/passive-compon ... series=SPR

I plan on using them a lot more in future builds. They sound fantastic!

-Ryan

Hi Ryan,
in which positions will you use these resistors? the question will seem trivial but given the range of power dissipation they have they can be used anywhere.
Thanks, Frank

[rccolgan]

A little secret, I'm 99% sure that the Kiwame resistors are SPR series Koa Speer (or the other way around?) These guys agree too: http://beezar.com/pho-bzr/catalog/produ ... cts_id=135

https://www.mouser.com/c/passive-compon ... series=SPR

I plan on using them a lot more in future builds. They sound fantastic!

-Ryan

Hi Ryan,
in which positions will you use these resistors? the question will seem trivial but given the range of power dissipation they have they can be used anywhere.
Thanks, Frank

I like them as the final 2k2 voltage dropper on the power supply as well as 1.5k cathode resistors. My next amp I'll try to source as many as I can as the primary resistor and then fill in the gaps with something else. I wish they still had the 100k & 110k... Maybe they will reconsider in the future.

-Ryan

[Stephen1966]

Maybe someone can help me out here?

I've been looking at the rectifier design using the four 1N4007 diodes and the caps. In Merlin's book on power supplies he calls the caps 'slugging caps' rather than 'snubbing caps'.

Snubbing implies burning energy off as heat, whereas slugging capacitors only spread the energy out, transferring it to lower frequencies.

I'm interested in using the fast recovery RGP10M diodes in place of the 1N4007s as I expect the transients (switching noise) will be quieter. Frustratingly, I read here (somewhere!) that slugging caps shouldn't be used with the superfast switching diodes because they interfere with their operation, but without any explanation of how or why. So I breadboarded the rectifier circuit, as a full wave bridge, and went hunting for the transients.

1673121232576.jpg

Merlin's oscillogram on page 49 shows a comparison between 1n4007s without a cap, with a slugging cap and with a snubber. The slugging cap added has a much longer "sine-like" tail which lasts for about 160 microseconds whereas both the diode without and cap and with a snubber show a much shorter, spikier transient - each less than 10 microseconds long.

I tried to replicate his experiment but unwittingly, I had the horizontal scale set at 5ms and Merlin had his at 20us. So I have to run the experiment again in any case, and unsurprisingly, the scope traces I saved don't appear to show the transients in any detail.

SDS00018.jpg

SDS00019.jpg

SDS00020.jpg

SDS00021.jpg

I'm assuming then, I missed the transients on this occasion but I am really not clear why the slugging caps would not work fine with the faster diodes. Does it have something to do with capacitor timing? Does it affect the current that can be delivered? Do these things contribute to a "buzzing" noted elsewhere? By buzzing, are we talking about oscillation?

The upshot of all this, is that I don't intend to use the slugging caps with the RGP10M diodes, but still, I would like to understand why people say the caps are a bad idea.

[ViperDoc]

A little secret, I'm 99% sure that the Kiwame resistors are SPR series Koa Speer (or the other way around?) These guys agree too: http://beezar.com/pho-bzr/catalog/produ ... cts_id=135

https://www.mouser.com/c/passive-compon ... series=SPR

I plan on using them a lot more in future builds. They sound fantastic!

-Ryan

Excellent pearl, thanks for dropping it.

I’ve been using metal oxide for power string dropping resistors (or whatever is on hand). I built a Silver Jubilee and used MO on the plate loads and noticed the amp has an incredibly wide bass response. Does this transfer at all in the power string?

[cys]

I found this discussion of caps with "slow" and fast diode rectifiers: https://ampgarage.com/forum/viewtopic.p ... 70#p277970

[ijedouglas]

I found this discussion of caps with "slow" and fast diode rectifiers: https://ampgarage.com/forum/viewtopic.p ... 70#p277970

Great find. I think I saw a similar discussion elsewhere but this lays it out clearly. Thank you