DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 09 Apr 2020, 06:21

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 29 posts ]  Go to page 1, 2, 3  Next
Author Message
PostPosted: 10 Jul 2015, 11:48 
Offline

Joined: 10 Jul 2015, 10:50
Posts: 20
Hello everyone! :D

I'm building an tube amp based one the ceriatone 2204 50w (clone of jcm800 with some mods). I've built most of it and now I'm about to finnish. However I have some doubts about the transformers.
Searching around the web I've saw lots of models of transformers (original and replacements) that work with this amplifier but I wasn't able to figure out some infos/specs about them.

This is the schematic (amp) I've been following:
http://www.subeimagenes.com/img/jcm800-2204ceriatone-83067.jpg
I saw lots of people building amps like this one of the schematic, but everyone uses manufactured transformers.

The deal is that there's a friend of mine working on a company that builds transformers (High quality ones) and he said he can built them for me (with a very reasonable price) if I give him the right specs needed for each transformer. :D :D
I was able to figure out the specs for the choke transformer and for the power transformer, but I'm not sure about the output transformer specs.

Here where I live I wasn't able to find any of the transformers needed with a reasonable price. I've searched on the web too, but the final prices ( including taxes + shipping ) are always too high. There are some shipping issues too.

Does anyone have any schematics for these transformers, or at least the spectifications so I can make some schematics for my friend (the one who will build the transformers)?

Later I can post the models (part numbers) of the transformers I've found that can work with this amp, also informations/specs and I have some pictures of the on going work with the amp. I'll not post them right now cause I'm not in home.


Top
 Profile  
 
PostPosted: 10 Jul 2015, 19:09 
Offline

Joined: 24 Feb 2009, 03:24
Posts: 562
Location: USA
https://www.edcorusa.com/xpp25-8-7_6k
This OT PP is suitable for Your PP EL34 - for 30 $, if your speaker is 8 ohm, /amazing PP OT for audio and guitar amp/.
If it is 4 ohm, You can use https://www.edcorusa.com/xpp25-4-7_6k
This amp is guitar amp, as I understand? But with 2 x EL34 and +U about 400 V, Your power will be no more 35 Wt, IMO.

_________________
Hi End is back proportional to the number of composite parts!
Projects: OTL 6AS7 Gen, Electric, SEs 2A3 RCA, 300B JJ, 6S4S, 4P1L, EL11 Telefunken, 6AS7 RCA, 6S33S, 6S41S, 6S19P, PP 6005 Gen. Ellectric , headphone ampl. OTL Loftin White 6AS7 RCA....SE E84L& E80CC Siemens&Tel-n.
http://azazello-sound.blogspot.com/


Top
 Profile  
 
PostPosted: 10 Jul 2015, 21:19 
Offline

Joined: 10 Jul 2015, 10:50
Posts: 20
Hey! Yes, it's an amp for guitar. I know about the output wattage with 2 x EL34, I just put the info there because it's what the schematic says. The amp I'm building It's a clone from the JCM800 2204 (50w), but there's many versions of this amp. Thanks for the info anyway.

About the transformers you mentioned, thank you for the info. I was looking around their website and their final prices are almost the same as the prices I could get for have them made here ( here is a little cheaper). The biggest problem I found in buying from this site as in any other is that I get this kind of shipping costs:

FedEx ($300.33)
USPS Priority Mail ($55.75)

Just to clarify, I live on Brazil, and here the things tend to be very costly if we need to import something, and frequently they lost stuff while shipping. So I was trying to avoid all this and get them made here.

This without taxes I would pay.

As I remeber, I was able to find out specs (output transformer) for the primary winding they are almost the same in many models, the iron core, the gap and how many Ω in the primary winding, my biggest doubt was about the secondary winding. I have doubts about how many turns and what kind of wire (awg) I need, or maybe how many ohms the secondary winding should have. In the schematics I've saw there's always a detailed primary winding and on the secondary winding they just put the value of the speaker( 4, 8 or 16 Ω) and nothing else.

I think that for the other transformers I have the correct specs. I'll see what I have and post them here.

I never worked with output transformers, so I'll post what I have and see if you guys can help me to figure it out.

Thanks! :D


Top
 Profile  
 
PostPosted: 10 Jul 2015, 22:25 
Offline

Joined: 10 Jul 2015, 10:50
Posts: 20
Here are the informations I have about the transformers, I think the specs for the power transformer and for the choke, are ok. What you think?

Power Transformer:
Attachment:
power.jpg


Choke Inductor:
Attachment:
inductor.jpg


Output transformer: (Here is where I need some advice)
Attachment:
Output.jpg


There are some info I didn't translate, they are about thermal resistance, tipe of iron core, end strips and insulation.

Anyway, this is what I have until now.

I was talking with my friend earlier and he say that it would cost in dollars something about 60U$ to make these 3 transformers. It's that cheap cause it's a big company and they make all kinds of transformers. They make good quality products.
And as you can see It would be a lot cheaper making them here. Otherwise It would be too expensive to finish this amp.

And of course I still want that feeling of doing things, not just buying stuff. :D

Thanks!


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.



Top
 Profile  
 
PostPosted: 11 Jul 2015, 08:17 
Offline

Joined: 10 Jul 2015, 10:50
Posts: 20
Let's say I want to plug my amp on a 8Ω speaker, how many ohms should my secondary winding must have?


Top
 Profile  
 
PostPosted: 11 Jul 2015, 14:35 
Offline

Joined: 19 May 2011, 05:38
Posts: 44
Power transformers and chokes are very easy compared to output transformers. Output transformers are not usually measured in DCR but as an impedance. Mainly dealing with ratios and interweaving of the windings. Someone whom has experience winding transformers would be able to explain further.


Top
 Profile  
 
PostPosted: 11 Jul 2015, 15:19 
Offline

Joined: 10 Jul 2015, 10:50
Posts: 20
Hey. Thank you for you answer.
I was reading about that today. I was searching about output transformers for a pair of EL34 and end up in this page:
http://www.turneraudio.com.au/output-trans-theory.htm
I read it a bit and found very interesting information about turn ratios and usual impedances for this kind of transformers.

As you said, this transformers are a little bit more complicated. I have little knowledge and no experience in winding output transformers and I would be pleased if someone could explain me a bit more about them.

Someone here ever tried to make an opt transformer for a pair of EL34? Any advice about types of iron core, wires (awg) and turn ratio?

I have some transformers winded and calculated by myself for some older projects ( not tube amps ). The idea I have in mind about making a transformer is always related to step up or to step down some AC voltages, so I have to calculate the turns, type of wire, core, gap and power. I'm a little confused about this output transformers. I know they work in the same way, in this case transforming the high voltage and low current of the valves output in lower voltage and higher current for the speakers, but I'm a little lost as I never worked with this kind of transformer.

I want to see this amp alive. So I'm looking for some advices about building this opt. :D

And of course, with a working example/prototype of a opt it would be a lot easier to understand about their operation and about push-pull valve amps. :D

Thanks.


Top
 Profile  
 
PostPosted: 11 Jul 2015, 17:33 
Offline

Joined: 10 Jul 2015, 10:50
Posts: 20
Again I was talking with my friend and he said they use a software to do all the precise calcules for the transformers, so for example, for a power transformer I need to inform him the input (mains), the output I need and the transformer power (watts) and the software will say all the informations to the machines that do the winding.

But for a output transformer, what kind of informations do I need?

Thanks.


Top
 Profile  
 
PostPosted: 11 Jul 2015, 23:48 
Offline

Joined: 10 Jul 2015, 10:50
Posts: 20
I'll try to do some calcules tomorrow and post it here!


Top
 Profile  
 
PostPosted: 11 Jul 2015, 23:59 
Offline

Joined: 24 Feb 2009, 03:24
Posts: 562
Location: USA
As I remember, I calculated PP OT for EL34 and I used iron core about 12-14 sq cm/0.2 or 0.3. Primary coil for penthode mode with about 2 x 1800 turns / 0.25. For UL mode - wire from 40 % from middle point. Secondary - 150+40 turns for 4 and 8 ohm/0.8 - 0.9. You can try, for guitar amp these data are not very critic.

_________________
Hi End is back proportional to the number of composite parts!
Projects: OTL 6AS7 Gen, Electric, SEs 2A3 RCA, 300B JJ, 6S4S, 4P1L, EL11 Telefunken, 6AS7 RCA, 6S33S, 6S41S, 6S19P, PP 6005 Gen. Ellectric , headphone ampl. OTL Loftin White 6AS7 RCA....SE E84L& E80CC Siemens&Tel-n.
http://azazello-sound.blogspot.com/


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 29 posts ]  Go to page 1, 2, 3  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: Google [Bot] and 7 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Op-amp Projects :: DIY Phono Projects :: DIY Cable Projects :: Hi-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy