Ceriatone HRM - Eric Gales Two Rock Please Help

[Fender0740]

Currently got my pen and paper out designing!

Hey Matt, how you coming along with your design for the Tube Recifier, is there a way of converting the standard Ceriatone HRM from SS to TR?
The reason I say the standard Ceriatone HRM is because its based on the Skyliner circuit which after hours of listening to clips and reading the differences between that and the Bluesmaster the skyliner seems to tick all the boxes, so then there is another bridge to cross to convert from 6L6 to El34/GZ34.

If you two want to "Hijack" go ahead, you know a lot more then me and im grateful for all your help

[Colossal]

so then there is another bridge to cross to convert from 6L6 to El34/GZ34.

Just a reminder ...6L6 and EL34s are power tubes. GZ34 is a rectifier tube. The rectifier's sole function is to convert AC power to DC. This can be done via solid state diodes (e.g. 1N4007, UF5408, etc) or a vacuum tube (GZ34, 5U4G, 5Y3GT, etc). To "convert" from one power tube type to another, your output transformer should (ideally) be able to cope with the impedance that each tube type presents. For a 50W amp (two output tubes), EL34s usually like to see 3.4k and 6L6s around 4.3k primary.

[trane34]

Just go with a 183 and have Nik wire up whatever rectifier you want. His chassis has the tube sockets. I'm building a 183 kit right now with dual tube recs with an ot for dual el34s. Non hrm but really I think you are splitting hairs. To me the clip you posted sounded like a lot of dirty cleans. Could have been the speakers. I started with a ctone bluesmaster. I didn't go for that kind of dirt as I played with some jbls. I bet with some Jensen speakers you wouldn't have a problem dialing that tone in. All of these amp are really tweak able to get a wide range of gain and tones.

[Fender0740]

so then there is another bridge to cross to convert from 6L6 to El34/GZ34.

Just a reminder ...6L6 and EL34s are power tubes. GZ34 is a rectifier tube. The rectifier's sole function is to convert AC power to DC. This can be done via solid state diodes (e.g. 1N4007, UF5408, etc) or a vacuum tube (GZ34, 5U4G, 5Y3GT, etc). To "convert" from one power tube type to another, your output transformer should (ideally) be able to cope with the impedance that each tube type presents. For a 50W amp (two output tubes), EL34s usually like to see 3.4k and 6L6s around 4.3k primary.

Haha, thanks Colossal for the reminder And thank you for that info,
Is it worth getting the transformer that comes with the Ceriatone kit (would that be able to cope with the impedance of each tube) or should I just buy my own probably a mercury or a magnetic components and save on shipping?

[Colossal]

Is it worth getting the transformer that comes with the Ceriatone kit (would that be able to cope with the impedance of each tube) or should I just buy my own probably a mercury or a magnetic components and save on shipping?

No offense meant to Ceriatone, but I would definitely go with either a Mercury or Magnetic Components. Quality for either brand is very high, tone is very, very good, and the money and jobs stay in the US. Mercury also offers a guarantee that if you don't like the tone of your chosen part, you can return within 30 days (provided the leads have not been cut).

[Fender0740]

[/quote]
No offense meant to Ceriatone, but I would definitely go with either a Mercury or Magnetic Components. Quality for either brand is very high, tone is very, very good, and the money and jobs stay in the US. Mercury also offers a guarantee that if you don't like the tone of your chosen part, you can return within 30 days (provided the leads have not been cut).[/quote]


Mercury Transformer it is then.
Now sorry if this is a stupid question but what do they contribute towards in tone?

[Colossal]

Now sorry if this is a stupid question but what do they contribute towards in tone?

Not stupid at all. Everything starts with the transformers. The PT transforms AC power to higher voltage AC where it is then converted to DC by the rectifier. At the end of the chain, the OT transforms DC power back to AC to power the speaker. Everything in the signal path has a sound; resistors, capacitors, the tubes themselves, the wire. Their physical characteristics and materials behave in a certain way and influence the shape of the wave moving through them. The sum of these parts and even the placement of the components and wiring (lead dress) create the tone of an amplifier. Great, great debate and partisanship exists over this.

For the manufacturer's part, the quality of materials, precision (reproducibility from part to part), design, all play a role in how the part ends up performing. The OT is especially important as we are concerned with how it performs over a range of frequencies. Valve Juniors sound pretty awful out of the box due to their weak, anemic OT, low quality parts. But they are built to a price point; their job isn't to sound good, it's to be inexpensive. Replace the OT with something of better design, quality and bandwidth, and whoa, there's a good amp in there.

You can always hear the difference with a hand wired amp made from quality components. The difference however is philosophical as tone is in the ear of the beerholder. There is no right or wrong answer, only what you like.

[martin manning]

To pick a small nit, it's the different tube types that have to cope with the impedance presented by the output transformer, not the other way 'round. A 4k primary will work fine for both 6L6 and EL34, and if the sockets are wired correctly swapping tube types only needs a re-bias. What power transformer will be used? Off-hand I don't know of any off-the-shelf part that has the right specs for this, but perhaps a Boogie Dual Rectifier unit would work. If not a custom wind will be required. You'll also need to install a small transformer for the relay supply unless the PT you get has an extra winding for that.

Have you thought through the total cost of this project? There's the C-tone amp chassis plus the PT and OT, which will be expensive if you go with MM, and a few more dollars for a relay transformer if necessary. Then I assume you'll be paying someone to install these parts, and that might not be a simple drop-in, requiring some chassis machining in addition to the wiring. That will surely the case if an auxiliary transformer must be added.

[Fender0740]

That is simply the best answer I could of asked for, explained perfectly thanks again Colossal you certainly know your stuff, I know I'm going to learn a great deal from this forum!

So in regards to make this sound like the EG Two Rock, the Tube Rectifier is doable but the rest seems like impossible? The layout (just from gut shots) seems completely different..
If I can just get this amp so its fairly high gain, articulate at high gain settings, nice low end, has that pronounced mid range that the TR has and is able to bypass the clean tone stack via a foot switch like the original EG does then I will be a happy man.
If only there was a Schematic for the EG available

Does anyone know which circuit the EG is based off yet at all?
Skyliner? Bluesmaster? Something else entirely?

[Fender0740]

To pick a small nit, it's the different tube types that have to cope with the impedance presented by the output transformer, not the other way 'round. A 4k primary will work fine for both 6L6 and EL34, and if the sockets are wired correctly swapping tube types only needs a re-bias. What power transformer will be used? Off-hand I don't know of any off-the-shelf part that has the right specs for this, but perhaps a Boogie Dual Rectifier unit would work. If not a custom wind will be required. You'll also need to install a small transformer for the relay supply unless the PT you get has an extra winding for that.

Have you thought through the total cost of this project? There's the C-tone amp chassis plus the PT and OT, which will be expensive if you go with MM, and a few more dollars for a relay transformer if necessary. Then I assume you'll be paying someone to install these parts, and that might not be a simple drop-in, requiring some chassis machining in addition to the wiring. That will surely the case if an auxiliary transformer must be added.

Thanks for Chiming in Martin! - I have thought about the total cost but its still cheaper then buying the real thing for me, there are very few available in Europe which is the only place I can buy one from.
My old man has built several Amplifiers and will be helping me build this one, he is a experienced electrician with over 30 years experience also have all the machinery at hand in his workshop if needed so I'm saving cost there. Its just finding a way of putting it all together and what I need to do it.

[Colossal]

To pick a small nit, it's the different tube types that have to cope with the impedance presented by the output transformer, not the other way 'round.

Ack, thanks for the correction Martin!

explained perfectly thanks again Colossal you certainly know your stuff, I know I'm going to learn a great deal from this forum!

Thanks man, very kind. I pontificate and blather on clinically, but Martin and many, many others here really know their stuff. I've learned and keep learning a tremendous amount from them.

[martin manning]

Thanks, Dave; we're all still learning here, if not, why bother?

Here's a Boogie dual rectifier PS that will work for this, if you can source one of these PT's. It has the relay supply hung off the filament circuit, so if you did it this way you wouldn't need a separate transformer. I think you can just forget the DC power to V1 unless you want to experiment with that. Maybe you'd better get your dad to register on TAG? https://tubeamparchive.com/viewtopic.ph ... 971#207971

[halfbackstrat]

Ok, from the looks of things, I would start from either of the HRM or Bluesmaster. Listen to some on youtube and decide which you prefer.
Grab yourself a Mercury Magnetics PT transformer appropriate for this build. They have ones specifically for Ceriatone.

Drill holes for this rectifier PT somewhere appropriate on the chassis.
Next, get yourself one of the Mercury Magnetics rectifier power transformers and wire it's primaries in parallel with the main PT and make sure it has a tap that is 5V and at least over 4A.

Wire up the amp, but move the two EL34s to the V4 and V5 sockets. Now instead of wiring the main PT to the rectifier board, wire the 345-345V tap to both 5AR4s in parallel. You will need two limiting resistors for this, the value of these and how to calculate them is shown really clearly on that link i gave you earlier to Valve Wizard, awesome website.
The output of those two goes to where the output of your diodes would have gone (the standby switch looking at the ceriatone layout).
Next, wire the heaters of the rectifier tubes from the rectifier transformer.

I'm aware the Ceriatone has 6L6 tubes not EL34. Someone else will have to help you with the swap to that, I've never looked into EL34 Dumbles.

[M Fowler]

You can't just bolt in any power transformer into a Ceriatone chassis it will require you enlarge the opening and drill mounting holes. I've test fitted many different brands on the Ceriatone chassis and non were drop in.

Heyboer PT can be ordered with the extra relay winding if you don't want to add a small transformer.

Mark

[Colossal]

Thanks, Dave; we're all still learning here, if not, why bother?

Indeed! I owe you some beers Martin.

Here's a Boogie dual rectifier PS that will work for this

Next, get yourself one of the Mercury Magnetics rectifier power transformers and wire it's primaries in parallel with the main PT and make sure it has a tap that is 5V and at least over 4A.

Check out Mercury PT part number FDP-20:

351-0-351VAC (secondaries, centertapped)
51VAC bias tap
5VAC @ 4A (conservatively rated)
6.3VAC @ 5A (filament supply, centertapped)

I'm actually using this PT for a rack mount DR clone (but solid state rectified) for a fellow.