Poor Man's EQP1A (+MID) Mark 2

[ruffrecords]

Ian, this is very valuable info!!! Thank you!

Don't forget that was just my opinion.

And since we're at the topic of sound, could you tell us is, in this design, the tube makeup gain too coloured for mastering jobs, or just gentle and transparent enough not to impose too much of its personality?
I would certainly go for tube output stage, but I'm exploring  options since I'd like to build it as a dual mono unit so it can be used in mastering also...
I know it's too subjective question... but I had to ask... sorry  8) ???

Luka

I always set out with the objective of making my designs as unobtrusive as possible. I am never aiming to deliberately add colour but to provide the lowest noise and distortion within the capabilities of the technology. You can design tube stages to add deliberate colour but I do  not. I spent a lot of time in the early days trying different tube  topologies trying to find one that provided low distortion without NFB. I discovered the mu follower and the 6SN7 tube which together are capable of excellent performance. Using my poor man's tube gain make up stage you can build a 6CG7 mu follower stage (a 6CG7  is just a 6SN7 in a B9A envelope) or you can use a 6922

The only problem with mu followers is they have a limited drive capability - they cannot drive 600 ohm loads to professional levels. After a lot more work I came up with the Eurochannel which has the same low distortion as the mu follower but can drive over +20dBu into a 600 ohm load.

Both designs have very similar sonic signatures and are designed as far as possible to be transparent. Having said that, many people who have built them say the really like the sound.

Cheers

Ian

 

[shot]

Oh wonderful! Ian this is simply wonderful! 
Looking forward to building this unit!


Luka

 

[iampoor]

Ian, what formula are you using to calculate the eq points? I am interested in adding/changing a few. As I understand, since this is a passive unit, the entire network has to be designed with an input impedance in mind?

Thanks!

 

[iomegaman]

Ian I would be interested in a couple of boards but also an extra set of inductors for a project daring me to get off my arse...

By the way I am  going to be getting some of your helios boards as well...my current void in gear is decent EQ's...between building the REDD47 tube and Raphaels AD converter (and rebuilding a Tascam tape deck) I am kinda all over the map but this looks really cool...

 

[ruffrecords]

Ian, what formula are you using to calculate the eq points? I am interested in adding/changing a few. As I understand, since this is a passive unit, the entire network has to be designed with an input impedance in mind?

Thanks!

This was covered in some detail in the original thread. I produced a spreadsheet for people who wanted to calculate their own values. You can find it here:

http://www.ianbell.ukfsn.org/pics/capcalc.xls

Cheers

Ian

 

[ruffrecords]

EDIT:  Just realised I spelled my own email address wrong!! The one below is now correct!

The PCBs have arrived so get your orders in! Boards are £7 each plus the usual shipping charges. To order just email me at [email protected] with what you want and your shipping address. I will respond with a Paypal invoice.

Just a reminder that the assembly instructions can be found here:

https://www.dropbox.com/s/0qnhl32g6th33yw/AsemblyInstructions.pdf?dl=0

Cheers

Ian

 

[electric_diaries]

Nice one Ian, great project! Any updates about the inductors from Prescott?

 

[prescott]

I will get them in 1-2 weeks and as soon as I can I will post the orders!

 

[rock soderstrom]

Hi Ian, I have sent you my order for some PCBs.

Is there a basic drill template for the switches, I am a  looser in mechanics. 

Thanks!

 

[ruffrecords]

Hi Ian, I have sent you my order for some PCBs.

Is there a basic drill template for the switches, I am a  looser in mechanics. 

Thanks!

If my memory is good, the gap between the the switches is exactly 1.6 inches but I will check that.

Cheers

Ian

 

[Humner]

I will get them in 1-2 weeks and as soon as I can I will post the orders!

How do we order them?

 

[prescott]

PM me!

 

[Humner]

Thank you, PM sent.

 

[prescott]

White market store is open from now!
Please post your interest there!

http://groupdiy.com/index.php?topic=59613.0

Thanks!

 

[ruffrecords]

I have just updated the assembly instructions for the MK2. I have included a section on inputs, outputs and gain make up amplifiers as well as some notes on using different switches. You can find it in the PMEQP1A folder in the DIY section of my whizzy new web site:

https://sites.google.com/site/customtubeconsoles/diy

Cheers

Ian

 

[ruffrecords]

For anyone planning to use the poor man's tube gain make up amp (PMTGMU) with the EQ I have just completed a short document about alternative ways you can build the PMTGMU amp. It is under the PMEQP1A folder in the DIY section of my new web site:

https://sites.google.com/site/customtubeconsoles/diy

Cheers

Ian

 

[mus1k_freak]

is anyone working on a front panel or case for this? (preferably stereo)

and does anyone have a mouser (or other supplier) cart?

 

[Humner]

is anyone working on a front panel or case for this? (preferably stereo)

and does anyone have a mouser (or other supplier) cart?

I will be doing front panels for mine. Similar to what I have done in the past with laser etched cherry wood(see pictures below)

Will most likely include VU meters (mainly for bling factor). Happy to do a batch of panels for anyone who might be interested.

I would like to use the same ABS plastic 2u enclosure as I did with racking these PM1000 strips, but they are difficult to find now, so I'm trying to source other options.

 

[Humner]

I have sourced those enclosures again.

If anyone is interested I'm happy to help out providing panels + enclosures. Please PM me - if I get a lot of interest I will start a new thread. Can do different configurations (single or dual channel, stereo channel, VU or without VU etc).

 

[My3gger]

I always set out with the objective of making my designs as unobtrusive as possible. I am never aiming to deliberately add colour but to provide the lowest noise and distortion within the capabilities of the technology. You can design tube stages to add deliberate colour but I do  not.

The only problem with mu followers is they have a limited drive capability - they cannot drive 600 ohm loads to professional levels. After a lot more work I came up with the Eurochannel which has the same low distortion as the mu follower but can drive over +20dBu into a 600 ohm load.

Both designs have very similar sonic signatures and are designed as far as possible to be transparent. Having said that, many people who have built them say the really like the sound.

Cheers

Ian

Hi,

judging by many posts here, other forums and some tests it seems like haromic spread of ECC83 used in normal way (high anode resistor, etc.) has harmonic spread that isn't as good as some others. For example octal tubes like 6SN7/6CG7 you wrote papers about, can't find much that would go as deep about ECC83, except for mostly writing without real tests.
I would really like to know what you think about it, is it NFB that makes higher (and lower in this case)  harmonics so much lower that even ECC83 sounds good like this? Or is output stage giving more sound that masks input tube's harmonic spread? My tests seem to confirm this, although with pentodes where difference is obvious.
Couldn't find almost any comment from you about it while searching around. Please comments if you don't mind, i can write in another thread for Euroboard Mic Pre if needed. Thanks for any reply.