First filter stage in a 100W HRM

[benoit]

I just got my mouser order and realized I ordered the 100uF filter caps which is the 50W value. How critical is this? Can I get away with using them for now? I'm going to order them and install them when they arrive but will the 100uFs work for now?

[odourboy]

You should be okay. Might actually feel kind of cool - maybe a bit more squishy.

[Guitarman18]

benoit, I think you and I are at similar stages of discovery with the D'clone platform, and from what I have gathered throughout the threads here, traditionally, the 100W amps have usually got 220mf's for the first filter stage. Having said that, if you look closely at Funk's 80's build in the files section, you can see that he has used 100mf's on a 100Watter.

https://tubeamparchive.com/download/file.php?id=2751

This picture shows four 6L6's

https://tubeamparchive.com/download/file.php?id=2757

while this picture shows the F&T 100mf first stage filter caps.

The higher filtering should give you a tighter sound, which is desirable in the 100W build, but so it would seem, not the rule.

Hope this helps.

PS. I couldn't find any 220mf @ 350v at Mouser. Also some of their Nichicon caps won't be in until 05/20/08. So my build will have to wait......

[benoit]

You should be okay. Might actually feel kind of cool - maybe a bit more squishy.

Thanks. I'll give it a try.

[HiGain]

I have 100uF caps in my 100W D-amps. Plenty of bass and oomph for me.

In my fender amps adding too much B+1 filtering made them stiff and difficult to play. (BTW, in one in particular I added 100 ohms in series with the power tube plates, loosening it right up while retaining the bass punch).

You may have heard, some dumble amps have had a reputation for being stiff and hard to play. I'd say it's not a bad bet to assume that some of these amps had larger filtering.

On there other hand, there is 124, which is said by Gil to be loose sounding despite having 300uF B+1 filter caps. However, it is probably looser due to it's reputed dark sound and relative lack of midrange compared to other dumbles. In other words, filtering in the preamp has a huge impact on the feel of the amp, and can be manipulated to offset any stiffness imposed by heavy PS filtering. Maybe HAD upped the V1b cathode to 10uF in his amps to counteract stiffness imposed by larger filtering. Adding more low end compared to the 5uF might create the sonic impression of a looser tone.

Now that I've just confused the issue further, and before I verge into complete BSing, I'll stop.

[tonejunkie]

I have done this and a resistor instead of a choke in my 100W and I like the feel it is a little squishy but not too much so in my opinion.

TJ

[dogears]

Jake, #124 has 100K plates. 10uf on the cathodes has a higher bass knee than the 220K plate triode with 4.7uf. I have seen as high as 25uf on 100K plate amps.

I have 100uF caps in my 100W D-amps. Plenty of bass and oomph for me.

In my fender amps adding too much B+1 filtering made them stiff and difficult to play. (BTW, in one in particular I added 100 ohms in series with the power tube plates, loosening it right up while retaining the bass punch).

You may have heard, some dumble amps have had a reputation for being stiff and hard to play. I'd say it's not a bad bet to assume that some of these amps had larger filtering.

On there other hand, there is 124, which is said by Gil to be loose sounding despite having 300uF B+1 filter caps. However, it is probably looser due to it's reputed dark sound and relative lack of midrange compared to other dumbles. In other words, filtering in the preamp has a huge impact on the feel of the amp, and can be manipulated to offset any stiffness imposed by heavy PS filtering. Maybe HAD upped the V1b cathode to 10uF in his amps to counteract stiffness imposed by larger filtering. Adding more low end compared to the 5uF might create the sonic impression of a looser tone.

Now that I've just confused the issue further, and before I verge into complete BSing, I'll stop.

[mat]

BTW, in one in particular I added 100 ohms in series with the power tube plates, loosening it right up while retaining the bass punch

benoit, sorry for the hijack question

Higain, does that affect to the impedance of the OT ? Did You put the 100R resistors in series of the OT primaries (not the center tap) that are connected to the power tube plates ?

[HiGain]

Scott: Thanks for the correction! See I was BSing However, I do think preamp filtering can be a big part of stiffness vs looseness, yes?

Mat: No effect on impedance that I know of. You put a single resistor in line with the center tap of the OT. KOC talks about this in one of his books, and it works great in Fenders!

Jake

[mat]

Scott: Thanks for the correction! See I was BSing However, I do think preamp filtering can be a big part of stiffness vs looseness, yes?

Mat: No effect on impedance that I know of. You put a single resistor in line with the center tap of the OT. KOC talks about this in one of his books, and it works great in Fenders!

Jake

Ok, thanks for clearing that out. I'm little tempted to try what kind of effect it would give for my non-hrm build.. while I'm complitely satisfied how it is now..but..still..