Transformers Matter?

[KenD]

I have always been schooled that quality transformers, properly spec'd, are crucial for optimum performance and tone from a tube amp. That thinking is taken to obsession level by the DIY Hi-Fi audio crowd. Good iron weighs a lot. But then I look at this:

My Ceriatone Aunt Peg (clone of one channel of a B-15) has a power transformer rated for up to 5A of heater current. It runs 6L6 standard but it can easily run 2 x KT66 (about 1.3A each). The builder's spec says it weighs 13kg or about 28 lbs. without the head cab.

Bass : Aunt Peg | Ceriatone

The Frenzel Mini-Bassman ("inspired" by the Fender 5F6A Bassman) runs 6L6 standard but is also capable of running EL34 which draw 1.5A heater current each. That amp weighs only 15 lbs. according to the builder specs., or about 1/2 what the Ceriatone weighs.

https://www.frenzeltubeamps.com/mini-bassman

Sure, the Ceriatone chassis is a bit bigger but not 13 lbs. bigger. It seems to me that most of the weight difference must be in the transformers and, if that is true, then either:

- the Ceriatone is significantly over-spec'd; or
- the Frenzel is really pushing whatever power transformer it has on board;
- or somewhere in between.

I'm curious about this because I am seriously considering ordering a Frenzel. I have a reproduction of the Ampeg tone with the James/Baxandall tone stack in my Ceriatone and I would like to have the Fender 3 band attenuator tone stack along with that.

Thoughts? Comments?

 

[Old Garage-Bander]

Transformers don't push to their associated circuits. The circuits draw from the transformer according to the needs of the circuit.
Determine the needs of the circuit, size the transformer accordingly.
Or for a given transformer design the circuit accordingly.
Some margin for headroom never hurts.

 

[KenD]

Transformers don't push to their associated circuits. The circuits draw from the transformer according to the needs of the circuit.
Determine the needs of the circuit, size the transformer accordingly.
Or for a given transformer design the circuit accordingly.
Some margin for headroom never hurts.

Transformers don't push to their associated circuits. The circuits draw from the transformer according to the needs of the circuit.

Of course I knew that and didn't ask that. I was just curious about the very large discrepancy.

 

[Old Garage-Bander]

Of course I knew that and didn't ask that. I was just curious about the very large discrepancy.

Are you talking about the weight of these amps or just the transformers?

 

[KenD]

Are you talking about the weight of these amps or just the transformers?

I could/should have been more articulate with my question. I guess what I'm really after is info or experience about the Frenzel power transformer. Has anyone experienced problems with it being under spec'd? What got my curiosity going about it is the fact of such a wide discrepancy in amp weight which I attribute primarily to the different transformer weights.

I should also have pointed out that the Ceriatone is tube rectified whereas the Frenzel is ss. Does that reduce the demand on the power transformer such that the Frenzel can get by with less? I dunno.

Or my curiosity could just be misplaced - it could just be that the power transformer in the Ceriatone is very over spec'd.
Ceriatone: 2 x KT66 = 2.6A plus 2 X 6SLGT = 0.6A Total 3.2A
Frenzel: 2 x EL34 = 3A plus 3 x 12AX7 = 0.9A Total 3.9A

Or to put it another way, it appears that the Frenzel circuit is drawing approx the same heater current (or a bit more) from a power transformer that weighs half as much as the Ceriatone one.

 

[Bloomfield]

Having a tube rectifier requires another winding, typically 3A @ 5VAC, which is a heavy winding, and will add a fair bit of mass to the transformer compared to one with the same ratings but using a solid-state rectifier.

 

[KenD]

Having a tube rectifier requires another winding, typically 3A @ 5VAC, which is a heavy winding, and will add a fair bit of mass to the transformer compared to one with the same ratings but using a solid-state rectifier.

Ah ha! Thank you. That would certainly explain some of the weight difference. It might also explain why Frenzel no longer offers a tube rectifier option on that amp.

 

[Wasnex]

Transformers don't push to their associated circuits. The circuits draw from the transformer according to the needs of the circuit.

Although it's a common saying, the circuit does not draw current. Without the voltage there will be no current flow.

 

[AlexanderB]

Transformers (for power supply and audio) are sort of "plastic" in their performance, so to which degree the designer is willing to accept sag/compression/bandwith loss etc will determine how low spec transformer you will "get away with".
For me, the slightly veiled and grainy mids from tube amps is fine, but I really dislike the loss of low end dynamics and articulation I hear when turning up tube bass amps. The SVT might be OK, but I disliked its competitors.

 

[George Dennis]

I'm only here for @agedhorse 's reply

 

[Lostgallifreyan]

The Frenzel Mini-Bassman ("inspired" by the Fender 5F6A Bassman) runs 6L6 standard but is also capable of running EL34 which draw 1.5A heater current each. That amp weighs only 15 lbs. according to the builder specs., or about 1/2 what the Ceriatone weighs.

Can you see enough detail to gauge the difference in size or mass of the cores? Minimising saturation at low frequencies might be a reason to oversize the core.

 

[gtirard]

I have excactly the same question, except that I'm looking at Pure Tone Amps. The power / weight ratios are surprising, like 5 kg for 50 w or 10 kg for 100 W. Demos sound good but there is not many detailed specs, so...

Also Rheingold has a 100w amp under 10kg, and considering their great reputation of hi-fi tube amp, I would be surprized if it was under powered

 

[logdrum]

The Mesa Prodigy 488 which pushed 250 watts is 4 lbs lighter than the Ceriatone and certainly lighter than Mesa Boogie 80 - 100 watt guitar heads. Randy Smith himself chimed in, I think in one of the forums TGP probably and explained about the transformer design and the use of different materials and that is why it is a light tube bass head. I had one and sold it. It is loud and I had a SVT CL and the Mesa 400 (which I still have ) to compare. Andy or Wasnex -- if they chime in can explain. Also the Mesa 400+ is lighter than the SVT as well and that was before the advent of this new transformers. My guess is it it is about design.

I also have a Frenzel head and even though it is a tweed, and in this case it only gets 25 watts from 2 6L6 class AB. It certainly is heavier than a tweed. Frenzel also made a hifi mono block pushing only 30 watts out of 2 6550 and the monoblock is heavy, 50 lbs I think. I also think you can ask Frenzel to use different transformers. Many of the tube nerds main criticism of Frenzel, is that he used good but not the best components and I think "better" transformers also weigh more. When me and buddy in San Diego built all the DIY clones, he experimented on different transformer brands and they weighed differently but we did not really have any conclusions how much they mattered. Resistor and cap values and topology made more significant changes.

Did you try to ask Nik from Ceriatone? He is pretty knowledgeable.

I like his products and you just gave me gas to get this Aunt Peg.

 

[Lostgallifreyan]

Resistor and cap values and topology made more significant changes.

True, and likely by enough to explain all differences. A quick look at a bass guitar waveform shows that most of the time it's not pushing full RMS signal even with fairly strong compression, and if a big capacitance for peak output is used, the power transformer could be smaller as a result.

If the ratio of weights in output transformers varies hugely for similar power and impedance, that might be more significant.

 

[Gianni "Orlandez" Orlati]

I have always been schooled that quality transformers, properly spec'd, are crucial for optimum performance and tone from a tube amp. That thinking is taken to obsession level by the DIY Hi-Fi audio crowd. Good iron weighs a lot. But then I look at this:

My Ceriatone Aunt Peg (clone of one channel of a B-15) has a power transformer rated for up to 5A of heater current. It runs 6L6 standard but it can easily run 2 x KT66 (about 1.3A each). The builder's spec says it weighs 13kg or about 28 lbs. without the head cab.

Bass : Aunt Peg | Ceriatone

The Frenzel Mini-Bassman ("inspired" by the Fender 5F6A Bassman) runs 6L6 standard but is also capable of running EL34 which draw 1.5A heater current each. That amp weighs only 15 lbs. according to the builder specs., or about 1/2 what the Ceriatone weighs.

https://www.frenzeltubeamps.com/mini-bassman

Sure, the Ceriatone chassis is a bit bigger but not 13 lbs. bigger. It seems to me that most of the weight difference must be in the transformers and, if that is true, then either:

- the Ceriatone is significantly over-spec'd; or
- the Frenzel is really pushing whatever power transformer it has on board;
- or somewhere in between.

I'm curious about this because I am seriously considering ordering a Frenzel. I have a reproduction of the Ampeg tone with the James/Baxandall tone stack in my Ceriatone and I would like to have the Fender 3 band attenuator tone stack along with that.

Thoughts? Comments?

Don’t know anything about electronics but the Ceriatone does look much better than the Frenzel aesthetics-wise ..

 

[Killing Floor]

They’re more than meets they eye.

 

[KenD]

Can you see enough detail to gauge the difference in size or mass of the cores? Minimising saturation at low frequencies might be a reason to oversize the core.

Not really. I can see inside my Aunt Peg with 5A rated PT and I can see the pictures of the Trinity TripTop with 4A rated PT, but I can't see much in that picture of the Frenzel. However, both the Aunt Peg and TripTop appear to be larger in physical size.

Trinity Trip Top Kit – Coming Soon

Did you try to ask Nik from Ceriatone? He is pretty knowledgeable.

I exchanged emails with Nik when I was ordering the Aunt Peg to be sure that it could run KT66 and learned from him that the PT was rated at 5A. I think Nik did not do much "designing" of the circuit but instead followed the original Ampeg schematic pretty closely (except, of course, reducing it to one channel).

In fact, I don't have enough technical knowledge to be able to assess these differences on that basis. My interest/concern is simply this: I want to experiment with EL34 in the Frenzel amp, which I can't do with the Aunt Peg because it doesn't have a bias switch between the 6L6 and EL34 family of OP tubes and I don't want to get inside to change any components. Given the apparent physical differences in the PT can the Frenzel run 2 x EL34 in fixed bias mode without overheating and failing?

I suppose I will just have to ask Frenzel directly what the heater current rating is on their PT. I'll have to phrase that delicately because I don't want it to sound like "Are you sure you know what you're doing?"

 

[Old Garage-Bander]

Although it's a common saying, the circuit does not draw current. Without the voltage there will be no current flow.

You are absolutely correct.
My goal here was to keep it simple, while just explaining that the circuit determines the needs, not the transformer. Note that I avoided using units as I felt it would overly complicate things in this case. I wanted to keep it more "block diagram" in nature and less "schematic."

 

[Old Garage-Bander]

What got my curiosity going about it is the fact of such a wide discrepancy in amp weight which I attribute primarily to the different transformer weights.

You can't really derive any useful information about a transformer based on the entire weight of an amplifier.
That's like trying to judge the acceleration of a vehicle based on how large it is.

 

[Thegreatzambini]

I think they definitely matter as this traynor tube amp is only 22 pounds and I think they save the weight by using a different transformer and although I really like the sound of this amp it didn’t seem to have the volume/ heft you expect from 100 W tube amp

YBA100 – Traynor Amps