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Author Topic: New start  (Read 3482 times)
viortisi
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« on: November 20, 2013, 03:24:41 AM »

Hi all

I'm new to the forum, and I'm planning to build a 18W TMB EF86

I'm in the process to buy a kit from Ceriatone web site. As it is my first attempt on building an amplifier (but I'm experienced with electronics) I'm wondering if the kit comes with any documentation, building instructions, schematics for an easier construction.

Or Can you point to any guide available in the form or on the web?

In addition I'm evaluating if using the trasformers and valves provided from Ceriatone. What is your experience on this point?
Do you think make sense to try using other parts for this ? Do I get any advantage?

Thanks for the support

Vi
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wyatt
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« Reply #1 on: November 20, 2013, 09:41:48 PM »

No documentation beyond the layout provided on the Ceriatone site, not even a schematic.

The turretboard is already populated with the components, the rest you do yourself. But if you don't have any knowledge on amp building, you really need to do a lot more homework before attempting a build. The ladies and gentleman who built amps for Fender, Marshall, etc. in the day, and all the handwired ones today, got extensive training and testing in the do's and don'ts of soldering, lead dress (how to route the wires), order of assembly, etc. and built the amps very much like an assembly line. They didn't need to know anything about how the amp worked, its design, or how to troubleshoot/repair it, that was another department...you don't have that other department if the build goes wrong.

There are tons of blogs and forum posts covering various builds and many companies like Metropolous, Trinity and others have posted step-by-step instructions on many of their amps. Even if they don't cover the EF86 TMB, there information is priceless for learning "best practices." There is also an entire site/forum dedicated to 18-watt Marshall designs, it;s where non-historic circuits like the TMB preamp and the EF86 variant all started....it is www.18watt.com

Not sure where you are...in the U.S., it's usually cheaper to order the Ceriatone without transformers and buy something "local" (Classictone or Mojotone) and save on shipping (and customs) on heavy transformers. The same goes for the cabinet.

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viortisi
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« Reply #2 on: November 21, 2013, 11:39:34 AM »

Thanks very much for the Info, very helpful

I have seen a schematic on the web for the TMB version
http://www.keepandshare.com/doc/2194569/ceriatone-18-watt-tmb-schematic-a-3-layout-23-59k?da=y

Does this match the layout for the 18W TMB presented in ceritone website?

I leave in italy, so I will try to source most of the material here.
Regarding the trasformer, is any specific model and brand you reccomend ?
Is it worth to use Mercury one? I have been loking at the Mercury web and I have seen several trasformer option for the OT and PT? Which one do you suggest?
thanks 
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wyatt
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« Reply #3 on: November 21, 2013, 06:18:28 PM »

Well, you are talking about building the TMB EF86.

That would be this...
http://www.verelec.com/tijdelijk/images/Ceriatone%2018W%20TMB%20EF86.pdf

So, the original Marshal 18-watt was the Model 1974 (no relation to the year). It had a Normal and Tremolo channel, and realy is it's own amp, not like the large Plexi's at all. These amps were relatively rare, something many people spoke of but few had played (especially in the U.S.), so there was a big trend about a decade ago was to start making clones and then everything exploded with innovation. One of the innovations was to replace the tremolo channel with a Plexi-based preamp with Treble, Middle, Bass controls (dubbed the "TMB"). THe original TMB's used the 1974 Normal channel and the TMB channel, given both the original 18-watt tone and the Plexi-tone. The EF86 replaces the Normal Channel with a preamp more like the late '50's Vox AC15. So, now you have the TMB EF86, which is Vox-esque on one channel and Plexi on the other. This is what you are looking at building.

Some caveats I see...EF86's are very finicky tubes, they go microphonic rather easy...they always have...so you'll want to look into how to isolate the EF86 tube and reduce vibrations. Also, many find the stock TMB channel way too bassy and boomy, so expect this and be ready to research mods to tweak it.

Mercury Magnetics builds good transformers...but their price is disproportionately high. Since you are in Europe, look into options from TAD (Tube Amp Doctor), which is a Europe-based distributor.  There is also IGPW in Germany making beautiful transformers. I am sure there are other options.

http://www.tubeampdoctor.com/en/shop_Output_transformers_Output_Transf_for_Marshall/
https://www.ig-transformatoren.com/products_en.html

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viortisi
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« Reply #4 on: November 22, 2013, 11:56:37 AM »

I think I will move to the TMb version ...

Thanks for the Info on the Trasformer, I will do some serach to identify a product.

Now I'm looking for parts and as I'm sourcing them I would like to select good product with excellent performance, but I would require some reccomedation

Valves: I would like to use the following

EL84 Genalex Gold Lion
12AX7 Genalex Gold Lion
EZ81 JJ

Resistor,  Pot and Cap I'm not sure what to choose for the different part of the circuit, is anybody able to point me to recomendations?
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viortisi
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« Reply #5 on: November 22, 2013, 01:02:47 PM »

Following to the previous post

Using the schematic http://www.keepandshare.com/doc/2194569/ceriatone-18-watt-tmb-schematic-a-3-layout-23-59k?da=y

I have the following list 

Quantity     Name           Value
2   R1,R4                          1M
2   R2,R3                              68K
1   R5                                   22K
4   R6,R7,R13,R19   820
6      R8,R9,R11,R15,R22,R23   100K
1   R10                                   100
5   R12,R18,R20,R25,R26   470K
2   R14,R21                          56K
1   R16                              2.2K 2W
1   R17                              33K
1   R24                              8.2K 2W
2   R27,R28                      8.2K
1   R29                              130 5W
1   R30                               100 2W
1   R31                              1.5K  5W
1   R32                              100K 3W

2   C1,C2                      1uF/63V
5   C3,C7,C10,C12,C13      0.01u yellow
2   C4,C11                      0.0047u
2   C5,C9                      0.022u
1   C6                              22u/450V
1   C8                              500p
1   C14                              16U/450V
1   C15                              100U/450V
1   C16                              32U/32U
1   C17                              0.047 630V
1   C18                              0.01U/3KV

How do I choose the type of these components?

thanks
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wyatt
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« Reply #6 on: November 22, 2013, 02:52:37 PM »

If you buying the kit...they'll all be supplied. The resistors and caps that are mounting on the turretboard will already be soldered in place.

Absolutely no reason to substitute, people get picky over pointless differences.

Build the amp stock first, then mod to taste...one mod at a time so you can get a point of reference.
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wyatt
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« Reply #7 on: November 22, 2013, 05:39:41 PM »


1/2-watt carbon film resistors
2   R1,R4                          1M
2   R2,R3                              68K
1   R5                                   22K
4   R6,R7,R13,R19                 820
6      R8,R9,R11,R15,R22,R23   100K
1   R10                                   100
5   R12,R18,R20,R25,R26   470K
2   R14,R21                          56K
1   R17                              33K
2   R27,R28                      8.2K

Metal Oxide Resistors
1   R16                              2.2K 2W
1   R24                              8.2K 2W

Wire-wound Resistors
1   R29                              130 5W
1   R30                               100 2W
1   R31                              1.5K  5W
1   R32                              100K 3W

Polyester Film Caps, axial
5   C3,C7,C10,C12,C13      0.01u yellow
2   C4,C11                      0.0047u
2   C5,C9                      0.022u
1   C17                              0.047 630V

Ceramic or Silver Mica Capacitor Silver Mica will be a tad smoother breakup, ceramic will be a tad more aggressive
1   C8                              500p

Ceramic Capacitor
1   C18                              0.01U/3KV

Electrolytic Capacitor
2   C1,C2                      1uF/63V
1   C6                              22u/450V
1   C14                              16U/450V
1   C15                              100U/450V
1   C16                              32U/32U

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viortisi
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« Reply #8 on: November 23, 2013, 05:48:16 PM »

Hi

Thanks for the reply , very helpfull.

I have seen in the schematic for the 18W TMB  the presence of a PPIMV, Is this a master volume for both chanels (TMB and normal)? Do you reccomend this ?

Another point is the bias of the output stage.
The cathod bias is used in this schematic, do you think a fixed bias is possible in this type of circuit ?

What would be the difference in sound?

I heard about the possibility to switch between fixed and cathode bias. Any reccomendation on this?

thanks

 

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viortisi
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« Reply #9 on: November 24, 2013, 05:58:47 AM »

Dear Wyatt

I have looked athe the link you have provided for the transformer

on the TAD website I can see two models for the PT

http://www.tubeampdoctor.com/en/shop_Mains_transformers_Mains_Transf_for_Marshall/Mains_transf_for_Marshall_18W_Plexi_TAD_Amp_Kit_955


http://www.tubeampdoctor.com/en/shop_Mains_transformers_Mains_Transf_for_Marshall/Mains_transf_for_Marshall_18W_Plexi_US_version_3265

On the other web site

http://www.ig-transformatoren.com/catalog/en/transformers/mains-transformer/275/igmt-m18tmb?c=48

While for the OT I see the two options

http://www.ig-transformatoren.com/catalog/en/transformers/output-transformers/282/igot-m18r?c=49

http://www.tubeampdoctor.com/en/shop_Output_transformers_Output_Transf_for_Marshall/Output_transf_for_18W_Plexi_Kit_958

I can see some price difference on these, is any beeter than the other?
spec looks similar

The TAD OT has a 9.2k impedence rather than 8k

What you think?

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wyatt
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« Reply #10 on: November 27, 2013, 07:35:59 AM »

Yes, a PPMV would affect both channels.

As for the MV and the bias, I always recommend building stock first, then assessing and modding to taste.

For the transformers...pick your poison. The PT's are all similarly spec'ed, just made by different companies. As the OT, g for 8K, you'll get the best performance out of the EL84's.
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arledgesc
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« Reply #11 on: January 27, 2014, 09:58:32 AM »

Good job Wyatt on compiling a parts lists.   There are also the potentiometers listed below.

VR1, VR2, VR4    500K ohm, audio taper  (500K-A)
VR3, VR6, VR8    1Meg ohm , audio taper (1M-A)
VR5                    250K ohm, linear taper (250K-L)
VR7                    25K ohm, linear taper (25K-L)

And I put the schematic notation "CCW" near the appropriate pin of each pot for reference.  This means counterclockwise or across the pond anticlockwise position of the pot knob. 
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