Now that we have built them.........

[UR12]

Mark

I am planning on trying both taps eventually. I started with the 5200 because it is closer to what most EL34 amps use (3500 - 3750). I will be trying the 6600 before it's over.

[Funkalicousgroove]

FWIW, Ken Fischer said that the only Trannie that he designed with a 5K2 Primary was a Heyboer and it was meant SPECIFICALLY for players who use Les Pauls and Juniors and find the Neck Pickup too muddy. All others had the 6K6.

[Richie]

Yes but he also said this..

"""The new Trainwreck designed circuit as well as Ken's specially designed power and output transformers; offer a new sound for this model. Unlike the Komet 60, Ken designed the Limited to operate exclusively with EL 34 power tubes. This allowed him to design the circuit and transformers as well as select each component to get the very best from EL34 tubes without any compromises"""


I'm not a transformer expert,but I can see what your saying..depends on so many factors. One direction may give more power less distortion %..and frequencies change. The other way will give less power output and will also change frequencies, distortion ratio, and tons of other transformer info etc..

I guess you could look at it like a guitar pickup.. a hotter wound pickup will loose highs and bass will get flubby compared to a lower wound pickup. Alot more to it like how they are wound,what they are made of, but similar in the idea of how things sound.
But i would agree with the quote above,figure out a transformer to run one set of tubes to get the best, or most out of it.

Richie

[Allynmey]

Maybe a descreet switch on the chassis to switch back and forth? Maybe we can label it LP/Strat? Sound do-able?

Allynmey

[Funkalicousgroove]

Think about the design of the express though, the preamp is designed to have enough treble to castorate a gnat, but the OT has a HUGE p-to-p Impedance, and there's really low plate voltage (like 375V). It all works as a system, the low voltage and high primary round out the sound and keep it from being an icepick. If you lower the Impedance you're going to lose Bass response, and it's going to get brighter-so you've gotta make up for it somewhere, which requires re-designing the amp. Look at the Komet, It has MUCH higher voltage, and smaller bass and Treble pots (250K vs 1M). the coupling caps are larger to allow for more bass, but a smaller bypass cap on V1A to limit the bass coming out of V1 to keep it from getting muddy. It also has a Cut control to tame some of that extra high end from the lower primary and higher voltage.

My point is that when you change something as big as primary impedance in an amp as simple as this you have to change MANY things. At the low voltage an EL34 runs just fine with 5K2-6K6 plate to plate impedance.

[Richie]

we will soon see.. we have 2 amps with exact same parts,well try the different taps and see which sounds best..well sounds best to my ears.

Then we'll try it against a 3'd built amp that is here.. It is a bit different in transformers..the rest is the same as the others.. It will be fun to try..and see how they sound.. use the same tubes etc..same cab.,guitars etc..

Richie

[Funkalicousgroove]

That's a FANTASTIC experiment, can you post clips??

[jedd63]

we will soon see.. we have 2 amps with exact same parts,well try the different taps and see which sounds best..well sounds best to my ears.

Then we'll try it against a 3'd built amp that is here.. It is a bit different in transformers..the rest is the same as the others.. It will be fun to try..and see how they sound.. use the same tubes etc..same cab.,guitars etc..

Richie

So, what's the verdict?

[jelle]

Allynmey,

The Siemens EL34's rock so much, this is a very musical tube. The ones I have are labeled AEG and I believe Larry loves them too. For me the only better version is the xf2 but I havent tried those in an Express style amp yet but in my HV 1959 they rule!

Too bad they both are no longer made.

Jelle

[mac0611]

Hi Allyn,

thanks for everything you've done for us!!

I use:

Siemens EL34's biased@ -30vdc, 6K6 taps

Tungsram ECC83's in all pre slots

vol: 1:30

treble: 12:00

mid: 11:00

bass: 9:00

This is my LP settings, also, with bright switch in the up position. One problem I have that annoys the hell out of me is a high end fizz that I cannot dial out. I played with tubes, lead dress, etc, and nothing helps. I play through a marshall 4X12 with celestion heritage G12M's. The amp is almost there except for the fizz. (I used moose's trannies, too)

[Allynmey]

I just read over this thread and realized that was the only Express I built with 5.2K taps. Everyone I've built since uses 6.6K taps. The liverpool uses 5.2K however.

[drhulsey]

I just read over this thread and realized that was the only Express I built with 5.2K taps. Everyone I've built since uses 6.6K taps.

Allyn, did Richie make the comparison in tone between 5.2K and 6.6K What differences did you notice

[castor]

Hi Allyn,

I use 2 Svetlana winged C EL34 (In future I'll take 2 Siemens at an electronic fair) - Bias -32
pre tubes: 3 EI 12AX7 (I tried Grove tubes and Sovetek 12AX7LPS-LP - those I use in my soldano - but they seems to kill harmonic in clean sounds)
- volume: between 1 and 2
- full bright
- all other pots at 12

(this is with my Pensa MKII with HB, with a strato type guitar I use bright up at half (100 pf) and volume at 11)

cab: i have only a 2x12 Marshall
+ i use a Dr.Z Airbrake modded to low down the bedroom level a bit more

Castor

[jelle]

Aren't these amps designed around the Siemens EL-34?

[v846]

Aren't these amps designed around the Siemens EL-34?

Jelle,

I'm not sure if it was designed around that specific brand or he selected by trial and error. I had ordered and Express in the mid 90's and Ken said he liked the Siemens and older brown base Mullards the best in that amp, damn if I can remember if it was the very early xf2 or the big base xf1,have to dig up the notes..I do remember he did say the later xf2 didn't have the same bass response.....

David