Any Suggestions On Primazy Z For Champ Styles?

[rp]

I think I've scoured everything available out there. There is no consensus but the range is from 5K-8K. I don't know how to read load lines but I understand the Pz will shift as the plate and screen voltages shift and Fender Champs ran anywhere from 300V-420V from tweed to SF.

So, while anything form 5k-8k is correct maybe some of you have advice, or just a favorite value from experience and chosen by ear. My 5F1 w/ Pv 365V has an Allen (@ 8K I think) sounds really good to me, but maybe 5k would have sounded better. I think I'll try my first octal build as a 5C1 and I'm curious what to use this time. The 5C1 is going to be ~300V.

If anyone has a tweed champ, or any champ, or all the champs, you could do the amp community a big favor by testing for the turns ratio and posting it here for google to forever find. No one has done this yet, as far as I can tell, hence this question getting asked again and again.

[selloutrr]

I believe the tweed and black face were 5K then when CBS released the silver face they went 8K. That is why a lot of current manufactures offer both 5K and 8K.

I have 11 champs ('53-'80's) as they come in from rental I'll make a list and post it may take a few weeks the vintage ones don't come home for very long.

[Cliff Schecht]

I much prefer 5k and use this in all of my single-ended builds, 6V6 or other.

[rp]

Anyone have any brand faves at 5K/10W with 4 & 8 taps? I was psyched to use Edcor since I loved what I heard in the AX84P1 I built, but they can't add multi taps to the GX and X series so that's out. The MC Triode OT is a dink IME. Not sure what's left - mojo or weber maybe but after my Edcor P1 and Allen 5F1 OT experience I'm thinking small SE amps benefit from high quality overbuilt OTs.

Anyone try this Hammond in a Champ, especially in a 5C1?

P-T125DSE Hammond, Universal Single Ended 10 W, 70 mA
Primary Impedance (Ohms): 2,500 to 10,000, Secondary Impedance (Ohms): 4 to 32

[rp]

I much prefer 5k and use this in all of my single-ended builds, 6V6 or other.

BTW cliff, I'm guessing you tried the higher the Pzs. What did you hear btwn 5k and 7-8K?

[Phil_S]

I think your best deal and excellent quality are right here:
http://www.musicalpowersupplies.com/2.html
OT8SE

[rp]

Phil, I was aware of these, but forgot to ask about them. I agree for the money it can't hurt to try it and specs are exactly what I'm looking for, and I can try both taps. I was thinking of buying their Deluxe and Champ Ots just to use as dual Pz testers.

It's so hard to get past the made in China thing, but 99% of everything in my life - good or bad, low quality-high quality, cheap-expensive, is made in China so why care anymore. But I fear once I go down that road there will be little difference btwn my homebrews and an Epiphone Valve Jr.

This one would be perfect - have you tried it?

OT10SE
8W to 12W SE Guitar Amp Output XFMR
82Hz to 10KHz, 60mADC
7000 Ohm and 5000 Ohm inputs to 4/8/16Ohm Outputs

[Firestorm]

Anyone try this Hammond in a Champ, especially in a 5C1?

P-T125DSE Hammond, Universal Single Ended 10 W, 70 mA
Primary Impedance (Ohms): 2,500 to 10,000, Secondary Impedance (Ohms): 4 to 32

I used that one to repair some off-brand Champ-like clones from the '60s. But if you really want to experiment with different Pzs, look at the original Hammond 125 series; you get a MUCH larger range of impedance taps. Mate that with a 4-position selector switch and you can wire four different impedances to play with. This series was not specifically designed for SE use, so it isn't air-gapped (but as far as I can tell, neither were original Tweed Champ transformers). Since it can be used push-pull, the 125 has a center tap, so you can also play with connecting the 6V6 ultralinear.

Just a thought...

[Zippy]

rp,

Have you followed the thread on a Champ build?

https://tubeamparchive.com/viewtopic.php?t=13407

[Alexo]

P-T125DSE Hammond, Universal Single Ended 10 W, 70 mA
Primary Impedance (Ohms): 2,500 to 10,000, Secondary Impedance (Ohms): 4 to 32

The DSE is insanely giant for a 5C1. But on the bright side, you can stick an EL34 in one, so that can be cool. The Hammond universals are great for dirty little amps like champs and the like.

[Phil_S]

rp: I don't know where Matt is sourcing these right now. For a while they were being made somewhere in Central America. I've used his iron, and think it is a very fine value. He is picky about getting them built to spec and he has changed factories a few times when they were not giving him what he wanted. I am not familiar first hand with the SE models, but I believe his are designed to go head to head with Hammond and beat them in a number of ways. I suggest you email him and ask straight up how they compare to Hammond. What he tells you privately maybe a lot more than he is willing to post in public.

[jjman]

I've tried several impedances from 4-8k or so on my 5F1 build. I've listened closely for high end, volume and distortion. Plate is 375net @ ~13.5watts. I've never been able to hear any difference.

Some day I'll check with my scope.

[rp]

I've tried several impedances from 4-8k or so on my 5F1 build. I've listened closely for high end, volume and distortion. Plate is 375net @ ~13.5watts. I've never been able to hear any difference.

Some day I'll check with my scope.

I tried my 5F1 w/ the 8K Allen switching btwn the 4 & 8 taps with the 4 ohm speaker - that should give me 4K. I could hear the difference, I liked both. It's one reason I posted hoping someone else can make up my mind for me. Not sure an 8" is the best speaker for this. I know when I try switching output taps with a 2x12 and other amps the effect is very clear.

Zippy, I followed RJs thread, it never got into OT Pzs or what the originals used. I was hoping RJ's Edcors would have multi out taps but Edcor doesn't offer it.

The 5C1 is going to be on an expensive hifi type chassis showing off a ST 5y3 and 6v6 and a red 5693. I only get to drill the holes once. I really want to use the pretty Edcor and might just live with the one 8 ohm tap.

[Cliff Schecht]

If you draw the load lines on a 6V6 graph it's easy to see that 5k is about the perfect load for a 6V6. These tubes are known for their sweet mids and smooth high end and I've personally found that the slight reduction in bandwidth with a 5k transformer works better with the sound that I go for with SE amps (which can be quite shrill if they aren't designed right). The other thing is that 5k gives you slightly more headroom which is a blessing in a SE amp that are really easy to overdrive (I love that great saturated SE output tube sound but too much can sound buzzy and, well, overdistorted).

[Zippy]

Zippy, I followed RJs thread, it never got into OT Pzs or what the originals used. I was hoping RJ's Edcors would have multi out taps but Edcor doesn't offer it.

Given that there are going to be several iterations of the Champ-derived amps in RJ's thread, I think this could be a valuable contribution there. I also know that RJ is working with Edcor on doing some custom trannies - short of the double primaries, you may be able to get exactly what you need regarding impedance.

Thanks to both you and Cliff for this conversation.