What tonal diff ? (OT question)

[iknowjohnny]

I have a marshall style build which i decided to try 6L6 in a while back and have been using it like that since. The 6L6's just sound better to me . The OT is a marshall style magnetic components at 3.2k. I noticed that the 6L6 fender style OT's on the mag comp site are from 4.2 to 6k. What tonal difference do you think i would find if i went to one of those? Also, Is there more to it than just the primary impedance?

[martin manning]

Can you miss-match the speaker by running an 8 ohm cab on 4 ohm setting? That would tell you exactly what you want to know.

[iknowjohnny]

Well, i'm running 6L6 at 3.4k right now, so maybe that could be considered a mismatch but likely not as much as doing what you suggest. If i move the selector am i not mismatching it again tho in a different direction? Hard to figure what i'm getting compared to using the exact "proper" imp. i would think.

[Roe]

fatter and dirtier with lower Z, thiner and more scooped with higher Z. more 3rds, 5ths, and 7ths with the lower Z

[martin manning]

Switch it and see. It'll be like that but not so much.

[Phil_S]

I think 6L6 are more typically run into around 6.6K or 8K primary. If you have 3.4K primary now, then doubling the speaker impedance will double the OT primary impedance. So, as Martin says, plug 8z speaker into 4z jack and you'll have 6.8K primary. I don't know what output impedance settings are available to you on this OT, but you can also run 16z speaker into an 8z tap for the same effect.

Did you make a typo? First I see 3.2K, then 3.4K primary. Whichever, double that to 6.4K or 6.8K.

With 6L6 tubes, I don't think I'd actually call it a mismatch. I'm not sure it matters what you call it.

[Colossal]

I think 6L6 are more typically run into around 6.6K or 8K primary.

Phil, did you mean 6V6s here? 6k6 - 8k is the typical Zpri for 6V6s in push/pull.

[martin manning]

What's an exact match? If you define that as having the theoretical load line pass through the knee of the Vg1=0 curve, then you need to know the plate and screen voltage and bias type too. With 400V on both plate and screen a 4k load will do it for a fixed-bias P-P pair of 6L6.

[Phil_S]

I think 6L6 are more typically run into around 6.6K or 8K primary.

Phil, did you mean 6V6s here? 6k6 - 8k is the typical Zpri for 6V6s in push/pull.

No, I meant 6L6. I'm looking at this from Duncan's TDSL. Look at AB1 and AB2. I realize that, as Martin points out, you've got to draw a load line. I'm also attaching a page from the RCA data sheet.

So, please educate me. What did I miss? I never went to class

[iknowjohnny]

Did you make a typo? First I see 3.2K, then 3.4K primary. Whichever, double that to 6.4K or 6.8K.

Yeah, typo there, as i meant 3.2k. But on a side note, after you posted this i began to wonder if it was 3.2 or 3.4, i coulda sworn 3.2 but it's been a while. So i looked and all mag comp marshall models say 3.6k ! Now I'm pretty sure that they were NOT 3.6 when i bought mine unless i'm really spacing big time. Thats not a real unlikely possibility at my age. But i wonder if they changed them.

[John_P_WI]

IKJ,

You are correct, the Mag Comps from Antique had (have?) a different primary imp than those sold by Triode. I have two 50 watters on the shelf from Antique that I am sure are 3k2. IIRC they were less imp than Triodes offering. When I get home tonight I take a look.

John

[martin manning]

No, I meant 6L6. I'm looking at this from Duncan's TDSL. Look at AB1 and AB2. I realize that, as Martin points out, you've got to draw a load line. I'm also attaching a page from the RCA data sheet.
So, please educate me. What did I miss? I never went to class

Phil, notice in the RCA data the screen voltage is significantly lower than the pate voltage, which is not the case in most guitar amps. That reduces the current at the Vg1=0 knee, so a higher load impedance is required to hit it.

[iknowjohnny]

IKJ,

You are correct, the Mag Comps from Antique had (have?) a different primary imp than those sold by Triode. I have two 50 watters on the shelf from Antique that I am sure are 3k2. IIRC they were less imp than Triodes offering. When I get home tonight I take a look.

John

I emailed them and they just replied that they've always been 3.6k. Maybe u r right tho and they only speak for the ones they sell direct and those they don't may be ordered to any spec the reseller wants. Who knows. Anyways, thats a bit closer to the 6L6 target if mine is 3.6k.

[Firestorm]

You'd have to have better ears than mine to hear the difference. Fender usually ran 2 6L6s at 4K. Some people think they sound better at 8K. I'll bet 6K6 is the bomb. Oh wait; I've done that. It is. IMHO.

[John_P_WI]

IKJ,

I just googled p-tm050 and came up with this data sheet:

http://www.tubesandmore.com/products/P-TM050

It clearly states 3k2.


And Triode's offering:

http://www.classictone.net/40-18025.pdf at 3k6.