| Search | Login/Register
   Home » Melquiades Amplifier » Bias help (97 posts, 5 pages)
  Print Thread | 1st Post |  
Page 2 of 4 (97 items) Select Pages:  « 1 2 3 4 »
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Full range Melquiades implementation..  Solved...  Melquiades Amplifier  Forum     81  220964  02-23-2011
  »  New  Melquiades For Dummies™ - step by step...  Risk...  Melquiades Amplifier  Forum     24  129126  08-29-2007
  »  New  Building Melquiades: Chronicle of full-range..  Variable Resistors...  Melquiades Amplifier  Forum     43  247148  06-09-2006
06-12-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,537
Joined on 05-28-2004

Post #: 26
Post ID: 10764
Reply to: 10763
Sounds too good to be true
fiogf49gjkf0d

 Dominik wrote:
Tribute give me best price...
Romy,
Can You help me with choosing L1, L2, L3, L4?
http://www.hammondmfg.com/5cchk.htm
And DL1, DL2
http://www.magnecraft.com/time_delay_sensor_relays.php

Dominik,

The Magnecraft relays are excellent, so the Hammond chokes. In fact the Hammond chokes in my view even better then they shall be. The Tribute transformers are very fine but I am bit not at ease with what I see. He specified the 350mA amorphous transformer for 260Euro. That is very conservative price and therefore I wonder what the core size he will be using. Current offsets inductance and inductance offsets LF. If he whatever core size he uses gaps it for 350mA then how much inductance will be left? He needs to give you the inductance number at 350mA, 300mA, and 250mA. I afraid that at 350mA it will be 7H-8H left and it will be too low. If you drive this thing at 200V then at 300mA you are already at max plate dissipation, so unless you go for 160V-170V (that I feel a bit too low) then you would not need 350mA. Probably the optimum for a full range operation to have 200V and drive the tube at 200-250mA, that would make a cup for 270A-280mA good enough. With all of it you need to have 10H and up. An amorphous transformer for 260mA and 11-12H and with a price tag of 260Euro? Sounds too good to be true. Hm, can I have one extra pair for myself? For a full-range operation you need to target LF cut off at 15Hz, you will end up with 17Hz-18Hz, at full-power of cause.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-13-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,537
Joined on 05-28-2004

Post #: 27
Post ID: 10768
Reply to: 10763
The OPT’s gap and the choke inductance
fiogf49gjkf0d
Dominik.

There is one more factor that I forgot to mention. When you will be looking at your choke for your B+ of the output stage then relate it critical current to the amount of the mA that you asked the Tribute guy to guy your transformer. If Tribute gives you 10H at 350mA then Tribute uses a VERY good chunk of amorphous iron. I doubt that Tribute would as the cost of such a size of amorphous lamination would be around $350 alone. Still, if you are planning to drive across this transformer 300-330mA then this would be the current the will flow across your poser choke and the inductance of the choke you would need to calculate accordingly. If you have a high sensitively and would drive Milq from a half of 6C33C then you will be at 150MA and you would need more inductance in choke. I do not know what voltage are you planning to use but if it is 200V (that I feel optimum) then you would not need 350mA, 270mA would be much better for both plates. For Tribute it would not be a big deal to change the targeted current (it will be just a different thickness of gasket in gap) but for you a lower current might mean a saturated choke. So, the common rule of choke value calculation is to stay with double of critical inductance but in your case I would recommend to stay with quadruple of even more inductance. It would not really heart…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-14-2009 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 28
Post ID: 10774
Reply to: 10599
Power transformers
fiogf49gjkf0d
While on the subject of transformers, nice-looking R core power transformers can be obtained directly from www.dibao.com. Unusually, there is no minimum order.
06-18-2009 Post does not mapped to Knowledge Tree
Dominik
Poland
Posts 48
Joined on 09-14-2008

Post #: 29
Post ID: 10826
Reply to: 10774
Maybe it is true...
fiogf49gjkf0d
Hi,     I feel weird that I posting private emails, but maybe this will help somebody, besides me...

"Here some specifications to show that I am not a dummy.
Core weight for one transformers is 6 kg.
Total weight for one transformer slightly over 10 kg.
Afe (your friend will know what it is) is 29 cm2.
Amount of iron is comparable to a EI 150 with 6 cm stacking height!!.
Transformers will fit in a 14,5 x 14,5 enclosure, 17 cm high to give impression of size.
I made transformers for 6C33 before and I never cut down core size for any transformer!
Best transformers are made with big size cores and "few" copper windings to get low winding DCR.
Your friend is most welcome to order a pair too"


What do you think about that???


Best
Dominik



06-18-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,537
Joined on 05-28-2004

Post #: 30
Post ID: 10827
Reply to: 10826
The crash-guidance about the transformer ordering.
fiogf49gjkf0d

Dominik, I think you took it a bit wrong and delivered to Tribute a message with a wrong accent.

As I understated that was the reply from the Tribute guy. No one accuses him in cutting down core size but based upon the available inductance you will be available to choose what currant you would like your transformer to be gaped at.

The higher currant you drive the lower plate impedance and it might be useful in some cases. You chose 8:1 load that is in the middle of the road and you shall be OK with 200-300mA or with gap of 230-330mA.  Now how the “core size” play in all of it? Amount of lowers cut off frequency (at full power) is a subject of inductance. Inductance is a subject of 3 derivatives - core size, gap size, amount of wire. The amount of wire is fixed by the turns ration. The core size is fixed by the selection of the Tribute’s laminations. The only variable you have is to moderate the gap size (or the max DC currant the transformer will be handling). The higher currant the lower inductance. So, asking Tribute to make it 200mA, 250mA, 300mA or 350mA you will be changing your LF cut off. The in here is to know if it will be from 12Hz to 25 Hz or from 20Hz to 40Hz. To answers this question you need to know what is the core size Tribute uses. The “total weight for one transformer” is not accurate and in mostly irrelevant number, the size of the enclosure it will fill is also very abstract number. He needs to give you the inductance numbers at let sat 200mA and at 300mA and it will instantly show you very objectively the core size. Some manufacturer do not like use inductance numbers and they more accustom to talk about lower cut off at full power. That is inductance too.

I kind of supplied a lot of thing but it shell give you a basic idea what you need to look for. If you would like “your friend … to order a pair too” then he needs to give to the friend the inductance number at 250mA – that will let the friend to know what he will be requesting. Do not forget that Tribute guy knows very much what he does and he do not need your or mine help. However, knowing the objective capacity of Tribute core from a perspective of LF is something that will help you estimate what to order.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-19-2009 Post does not mapped to Knowledge Tree
Dominik
Poland
Posts 48
Joined on 09-14-2008

Post #: 31
Post ID: 10843
Reply to: 10827
Tribute Transformer specifications
fiogf49gjkf0d
Hi,
From Pieter:
"For me it is normal practice to do good specifications.
I go for 10 Hy's at 250mA.
10 Hy's with 512 ohms source impedance will give 8 Hz cut off frequency."

Best
Dominik
06-19-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,537
Joined on 05-28-2004

Post #: 32
Post ID: 10846
Reply to: 10843
The 10H at 250mA is a good size transformer.
fiogf49gjkf0d
You can gap it for 250mA or for 300mA – you still have some spare inductance. From what I see Pieter gave you a very good price for that chunk of core. If I decide to keep my “experimental” full-range SET amp (Sun Audio) then I will get from him a better transformer. Good luck you your project and let me know if you need any help along. 
 
The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-24-2009 Post does not mapped to Knowledge Tree
Dominik
Poland
Posts 48
Joined on 09-14-2008

Post #: 33
Post ID: 10898
Reply to: 10846
Power transformers and chokes.
fiogf49gjkf0d
Romy,
I already send money to Pieter for OTP transformers. Now I need power transformers and chokes.
This is Pieter propose: (He look at the schema)

2 x power supply transformer - 12,6V/5A
                                                    - 6,3V/1A

2 x power supply transformer - 440V/100mA
                                                    - 220-0-220V/80mA

2 x power supply transformer - 240V/500mA

2 x power supply chokes 10H/500mA

2 x power supply chokes 20H/100mA

4 x power supply chokes 30H/40mA

"Power supply transformers use 0,3mm silicon steel c-cores.
10H chokes are 0,3mm silicon steel c-cores.
20H and 30H chokes are 0,05mm silicon steel c-cores.
All transformers potted."

Need sugestion from You...


Thanks
Dominik
06-24-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,537
Joined on 05-28-2004

Post #: 34
Post ID: 10899
Reply to: 10898
Transformers, chokes, etc…
fiogf49gjkf0d

Dominik,

I do not think that you need suggestion from me. If Pieter looked at the schema then everything is very much identifiable in there and he shall know what to do. Let me to give you alternatives that are not at the schema.

The 12,6V/5A, 6,3V/1A filament transformer might be as proposed but it might be also just simple 6,3V transformer with 8-10A secondary. You see, the 6C33C has two pair of heated and you might connect them in series or in parallel. There are many debases what is better, both camps have own reasonable arguments. I made the experiment and I was not able to hear difference between series or in parallel. I had 12V because I would like to keep current down (six driver filaments and six 6C33C filaments, each of 6C33C them 6A) but in your case what you have one 6C33C per amps you might stay with 6.3V only and use parallel heaters. The benefit of the parallel heaters that is you have good speakers that do not need a lot of power then you will be able to disconnect one heater and use just one anode of 6C33C – it will sound better….

The bias and the B+ for the first stage are fine.

The power supply chokes need to be warned. I do not know how Pieter does his chokes but some of the chokes do not work well in input choke application as they are too “loose”, not well varnished perhaps and in input choke application they have noise  - something that I hate very much. Explain to Pieter that the chokes will be work right after rectifiers and will see very high ripples. So, the chokes need to be made that they would not buzz. Pieter or whoever will do it will knows what to… Ironically the very cheap Hammond chokes are very well made from the perspective of “none-buzzing” in input choke application. They have even a custom version for each choke (10% more expensive) where they double-dip choke in epoxy (separate coil and separate assembled choice). They look ugly but you can drive the Hoover Dam currant across them and they still will be silent.

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-27-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,537
Joined on 05-28-2004

Post #: 35
Post ID: 11572
Reply to: 10843
The 6C33C OPT, is it done?
fiogf49gjkf0d
 Dominik wrote:
Hi,
From Pieter:
"For me it is normal practice to do good specifications.
I go for 10 Hy's at 250mA.
10 Hy's with 512 ohms source impedance will give 8 Hz cut off frequency."

Dominik, when you get your transformer from Pieter then can you post a picture of the core size? I am kind of contemplating to order my own transformer and I might it one from Tribute. I just want to have 10-11H at 320mA, so it needs to be a quite a chunk of core…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-28-2009 Post does not mapped to Knowledge Tree
Dominik
Poland
Posts 48
Joined on 09-14-2008

Post #: 36
Post ID: 11575
Reply to: 11572
Still waiting.
fiogf49gjkf0d
Hi Romy,
I am still waiting for OPT and chokes from Pieter.
We have a deal with Pieter that on begining ofSeptember he will by ready.
I have almost all parts-Waiting for package from partsconnexion...
I will make photos of OPT and post it here, in the meantime here are my power transformers...
toroidal transformer.jpg
03-04-2010 Post does not mapped to Knowledge Tree
miab
Canada
Posts 46
Joined on 02-07-2008

Post #: 37
Post ID: 13083
Reply to: 11575
Any further developments?
fiogf49gjkf0d

Dominik
 Any further progress on the project of the Melquiades? Curious about the transformers from Pieter. Any comments?

05-27-2010 Post does not mapped to Knowledge Tree
perrew
Posts 30
Joined on 10-06-2009

Post #: 38
Post ID: 13630
Reply to: 13083
Tribute still in business?
fiogf49gjkf0d
Anyone know if Tribute still in business, and if not can recommend company that has double coil on single c core for 2A3?
05-27-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,537
Joined on 05-28-2004

Post #: 39
Post ID: 13631
Reply to: 13630
Tribute never was “in business”.
fiogf49gjkf0d
 perrew wrote:
Anyone know if Tribute still in business, and if not can recommend company that has double coil on single c core for 2A3?
  
Tribute is a single guy who makes transformers. Get in touch with him and he will be “in business”. Mind you that it sometimes very difficult to talk with Tribute and he like to disappear from time to time. So, if you for a few weeks ca not get hold of Tribute then it is fine -  this is the way how Tribute communicate – he will show up soon or later. Also, do not forget that it I summer and Europeans do not work during summer…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-27-2010 Post does not mapped to Knowledge Tree
perrew
Posts 30
Joined on 10-06-2009

Post #: 40
Post ID: 13638
Reply to: 13631
The Disappearing Act Business
fiogf49gjkf0d
Ok, thats very good to know, I really hope he responds!And remember, the Europeans are so effective at work so they can do vacation in the summer.
10-10-2010 Post does not mapped to Knowledge Tree
ArmAlex
Iran
Posts 81
Joined on 02-15-2009

Post #: 41
Post ID: 14692
Reply to: 5561
Will Mel. drive Gryphon
fiogf49gjkf0d
Romy, I plan to build Melquiades. But there are couple of questions:
1-One of speaker options is Gryphon Trident, it is an active bass speaker so Mel should drive MF & HF only. In your opinion can Mel drive
   these speakers?
2-If yes then driving an active speaker Mel doesn't need to handle LF so what modification it needs to serve this purpose?
 
Regards, Armen
 
 Romy the Cat wrote:
Here is a separate thread where any questions and answers regarding how to build Melquiades might be piled up.
10-10-2010 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,537
Joined on 05-28-2004

Post #: 42
Post ID: 14693
Reply to: 14692
I have no idea Gryphon Trident are but…
fiogf49gjkf0d
 ArmAlex wrote:
Romy, I plan to build Melquiades. But there are couple of questions:
1-One of speaker options is Gryphon Trident, it is an active bass speaker so Mel should drive MF & HF only. In your opinion can Mel drive these speakers?  

Armen, I have no idea. What does it mean drive? To power Gryphon’s MF & HF only in the room of your size and do not send stages into A2? Mostly likely it will. Will it sound as it could with higher sensitivity drivers? I do not know but I doubt.

 ArmAlex wrote:
2-If yes then driving an active speaker Mel doesn't need to handle LF so what modification it needs to serve this purpose?  

I you have an active speaker and want like to use Melquiades then you need a DSET configuration, Find out where and how your Gryphon rolls off MF and introduce the same filter from your DSET in the amp. Use much lower value of coupling capacitor and OPT with much less inductance to optimize the amp for HF operation.
 
The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-11-2010 Post does not mapped to Knowledge Tree
ArmAlex
Iran
Posts 81
Joined on 02-15-2009

Post #: 43
Post ID: 14698
Reply to: 14693
Melquiades for Trident
fiogf49gjkf0d
I you have an active speaker and want like to use Melquiades then you need a DSET configuration, Find out where and how your Gryphon rolls off MF and introduce the same filter from your DSET in the amp. Use much lower value of coupling capacitor and OPT with much less inductance to optimize the amp for HF operation.

Dear Romy, Crossover frequencies are 250 and 2Khz, would you please be more specific about changes that is needed?
As I'm not very technical and a friend is going to help me to build Melquides.

Many Thanks, Armen
 
02-22-2011 Post does not mapped to Knowledge Tree
Dominik
Poland
Posts 48
Joined on 09-14-2008

Post #: 44
Post ID: 15608
Reply to: 11572
OPT from TRIBUTE
fiogf49gjkf0d


Hi,

Here is pic of my OPT from Pieter before poting. Each transformer is wound on 4 AMCC-160 cores

6c33c.JPG

02-22-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,537
Joined on 05-28-2004

Post #: 45
Post ID: 15609
Reply to: 15608
The AMCC-160 core.
fiogf49gjkf0d
Yes, the AMCC-160 it was what I was able to get for reasonable price. When you be done then measure response at full power and publish the result.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-18-2011 Post does not mapped to Knowledge Tree
Dominik
Poland
Posts 48
Joined on 09-14-2008

Post #: 46
Post ID: 15796
Reply to: 15609
Tribute transformers and chokes
fiogf49gjkf0d

Today recive transformers and chokes from Pieter.  I was prepare for size of OPT but not for size of PS chokes!!!!  

There is no paint on parts on my request. Here are  pics of most of the big parts,

tribute OPT.jpg

Now i must find a way how to put this all in two  monoblock enclousure when I do this then will need some help from You guys to make this thing work...



Best 

Dominik

03-18-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 454
Joined on 01-07-2006

Post #: 47
Post ID: 15799
Reply to: 15796
Baby caps
fiogf49gjkf0d
Dominik, babies doesn't mix well with tube amps!

Whar are the big caps? The toroids were also wound
by Pieter or do you have some GOOD local winder?


Cheers,
N-set



Cheers,
Jarek
03-19-2011 Post does not mapped to Knowledge Tree
Dominik
Poland
Posts 48
Joined on 09-14-2008

Post #: 48
Post ID: 15801
Reply to: 15799
Toroids from Poland
fiogf49gjkf0d
N-set,
The caps from pic is
C2   -2000uF
C10 -6000uF
Toroids transformer company  comes from my city http://www.toroidy.pl/index.php?option=com_content&view=article&id=6&Itemid=7&lang=en.


Yes, I know that tube amps(all audio equipment) and kids its not good mix, That is the one of the reasons that I  go to another place in 2 years, and will build dedicated room . For now she is to little to reach equipment Smile
03-19-2011 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 454
Joined on 01-07-2006

Post #: 49
Post ID: 15802
Reply to: 15801
Toroids
fiogf49gjkf0d
Thanks Dominik, pitty they wind only toroids, but look very nice!
They do show isolation type toroids however...

I've been winding with Telto but I feel their quality dropped, while
the prices jumped :-(



Cheers,
Jarek
03-19-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,537
Joined on 05-28-2004

Post #: 50
Post ID: 15803
Reply to: 15802
Think about ergonomics and esthetics of your design.
fiogf49gjkf0d
It looks like you will be building not DSET but a full range amp. You need to come up with the chassis design and it is a bit complicated possess. Do not be in hurry with this possess. You need to think about the location of the main elements on chassis, about the shortening and striating of signal paths, about separation of signal passes and power passes, about grounding, heat dissipation, galvanic proximity and many many other things. In your case there is a complication: Pieter made your transformer attractive looking.  This in many cases would lead people to make an amp chassis on a flat table with transformers, tube and caps sticking out of chassis like mushrooms. I personally do not like this design, purely on esthetics, even thought I agree that there are a lot of justifiable advantages in this flat panel anticlimactic design.

Sure, my personal taste in esthetics means nothing to you, and it is how it shall be, but I do encourage you to come with your own version of pleasant looking and smart design. I personally like what all elements of amp are hidden and transformers, chokes and caps are not exposed. But it is me…..

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
Page 2 of 4 (97 items) Select Pages:  « 1 2 3 4 »
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Full range Melquiades implementation..  Solved...  Melquiades Amplifier  Forum     81  220964  02-23-2011
  »  New  Melquiades For Dummies™ - step by step...  Risk...  Melquiades Amplifier  Forum     24  129126  08-29-2007
  »  New  Building Melquiades: Chronicle of full-range..  Variable Resistors...  Melquiades Amplifier  Forum     43  247148  06-09-2006
Home Page  |  Last 24Hours  | Search  |  SiteMap  | Questions or Problems | Copyright Note
The content of all messages within the Forums Copyright © by authors of the posts