ruffrecords

Re: Poor Man's Pultec EQP1-A
« Reply #360 on: October 06, 2011, 01:42:53 PM »
What works better, shorting or non-shorting switches?

The problem with an EQ like this is that you are switching capacitors. It does not matter if you have shorting or non-shorting contacts, the capacitor still needs to get charged and so you can get clicks. Having said that, there should be no dc on these capacitors so there should be nothing to cause switching clicks. if you do get clicks, the type of contacts used will not help. The cure would be to wire 4.7Meg resistors across adjacent pairs of contacts so there is a dc path for all the caps to charge through but in the prototype I built I did not find this necessary.

So, in short you are probably OK using either.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'


G-Sun

Re: Poor Man's Pultec EQP1-A
« Reply #361 on: November 08, 2011, 05:00:33 AM »
Not reading all 19 pages (sorry)..

What's the status of this project?
What's the cost of a unit?
Sound-examples?
Pictures?
HJFP2, ssl9k, Harrison Ford Filters
My music

mylesgm

Re: Poor Man's Pultec EQP1-A
« Reply #362 on: November 08, 2011, 05:18:55 AM »
RTM. (sorry)
Check my work at www.mylesmumford.com

baadc0de

Re: Poor Man's Pultec EQP1-A
« Reply #363 on: November 08, 2011, 05:33:58 AM »
Not reading all 19 pages (sorry)..
That's not the way you want to approach a tube project. I don't know how experienced you are, but statistically it's more probable that you haven't built much and in that case, please, read at least the whole thread and some of the others. These things can kill or at least zap you well.

What's the status of this project?
Two rounds of many many PCBs have been sold to my knowledge, which has probably made about 50+ people around the world very happy. I don't know if Ian has any left, but if there is interest, there could be a 3rd round?

What's the cost of a unit?
If you will browse around this forum, which you should if you are contemplating any project, this isn't how things are done around here. Project designers will create a PCB and possibly sell them along with some hard to find auxiliary components or some additional mechanic fasteners/brackets to offset development costs. Very rarely are there full kits offered and so what happens is that you select and order all the parts that go on and off the PCB, as well as the case that you want it in. Typically you will have to manage more than 5 different vendors selling different things. As with anything there is a range of prices available for any one kind of component, there are capacitors that cost 1 cent and capacitors that cost 100$ and both will fit into the project in the same hole and "do the same thing" but their subjective or objective quality may be different. So it's hard to say how much the project costs, it's better to ask, how much do you have / are willing to invest and see if you can get all the components for that kind of cash.

Sound-examples?
None that I know of. But it's a transformer isolated passive EQ with tube makeup stage. Can't go far wrong with that. With the right components I'm sure it sounds fabulous!

Pictures?
Even if there were any, all they're useful for is to get an idea of how you'd want to make the project, i.e. which case to use, how to drill it and position stuff, which knobs to use etc.. you have to use your own aesthetic.
« Last Edit: November 08, 2011, 05:37:02 AM by baadc0de »

ruffrecords

Re: Poor Man's Pultec EQP1-A
« Reply #364 on: November 08, 2011, 10:49:42 AM »
Not reading all 19 pages (sorry)..

What's the status of this project?
What's the cost of a unit?
Sound-examples?
Pictures?

Status: PCBs available for EQ and tube gain make up. Lot's of people have ordered PCB sets and built, it mostly into 1U rack boxes and mostly stereo units. Others have modified the EQ for their own purposes - for example one group member has built a bass guitar specific version.
Cost: A pair of EQ PCBs cost 7GBP and the optional tube gain make up PCB is 5GBP and  Paypal and shipping charges are 2GBP for Europe and 3GBP for the rest of the world. I still have some PCBs left.
Sound-examples: none as yet
Pictures: I have been sent one showing the EQ incorporated into a project but have been asked not to publish it.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

G-Sun

Re: Poor Man's Pultec EQP1-A
« Reply #365 on: November 08, 2011, 12:24:08 PM »
Thanks for you responses :)

Yes, I'm fairly new to DIY. Hallo.. :)

Yes, it didn't expect kits. Though 5 vendors sounds expensive (shipping to Norway).

Phrasing my questions a little different:
- What is typical cost per unit for the people here, building this project (singel channel)?
- What features does it have (like reading on the front-panel, the basic option)?
- Do I have to be very skilled to build it / get the right parts?

I'll soon build my first DIY, a Hamptone HJFP2, and is hoping to get some skills by that.

BTW: Do I always have to do these quizzes to post here? Almost had to ask on Gearslutz just to get the right answers
HJFP2, ssl9k, Harrison Ford Filters
My music

gemini86

Re: Poor Man's Pultec EQP1-A
« Reply #366 on: November 08, 2011, 01:34:41 PM »
Hi! Welcome! Trying to help you past this first speedbump. People around here generally don't care for laziness. Asking for all the answers in an open book test is right up there near the top of the list. When you're building something from parts and pieces,  yes,  shipping does add up. Some vendors try to supply parts kits but you gotta pay for the effort there as well. Good luck and please,  read!  You gain nothing by not researching.
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

ruffrecords

Re: Poor Man's Pultec EQP1-A
« Reply #367 on: November 08, 2011, 06:44:54 PM »
Thanks for you responses :)

Yes, I'm fairly new to DIY. Hallo.. :)

Yes, it didn't expect kits. Though 5 vendors sounds expensive (shipping to Norway).

Phrasing my questions a little different:
- What is typical cost per unit for the people here, building this project (singel channel)?
- What features does it have (like reading on the front-panel, the basic option)?
- Do I have to be very skilled to build it / get the right parts?

I'll soon build my first DIY, a Hamptone HJFP2, and is hoping to get some skills by that.

BTW: Do I always have to do these quizzes to post here? Almost had to ask on Gearslutz just to get the right answers

Here is a link to earlier in the thread where there is a picture and a comment on the sound

http://www.groupdiy.com/index.php?topic=43859.msg560160#msg560160

Total cost depends on what you decide to build. The EQ PCB costs you know. To that you need to add the cost of the capacitors and the pots which should be less than 20GB. Then you need a gain make up amp, a power supply and a case to put it in. You may want to have input and output transformers or you may choose to leave them out to save cost.

I would estimate the cheapest using a simple box, power supply, op amp gain make up and no transformers would be a around 75GBP.

if you put it in a 1U rack case you could at 25GBP to that figure.

If you add input and output transformer you can add another 100GBP

So the real answer is it depends.

In terms of feaures it is a poor man's Pultec EQP1A -so it has a similar set of features but cost reduced. So it has the same hi and low boost and cut but only 6 freuwncies for each band. The hi response is shelving rather than peaking because the inductor has been removed to save cost.


DIYers from beginner to expert have built this project.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

G-Sun

Re: Poor Man's Pultec EQP1-A
« Reply #368 on: November 09, 2011, 03:37:08 AM »

Here is a link to earlier in the thread where there is a picture and a comment on the sound

http://www.groupdiy.com/index.php?topic=43859.msg560160#msg560160

Total cost depends on what you decide to build. The EQ PCB costs you know. To that you need to add the cost of the capacitors and the pots which should be less than 20GB. Then you need a gain make up amp, a power supply and a case to put it in. You may want to have input and output transformers or you may choose to leave them out to save cost.

I would estimate the cheapest using a simple box, power supply, op amp gain make up and no transformers would be a around 75GBP.

if you put it in a 1U rack case you could at 25GBP to that figure.

If you add input and output transformer you can add another 100GBP

So the real answer is it depends.

In terms of feaures it is a poor man's Pultec EQP1A -so it has a similar set of features but cost reduced. So it has the same hi and low boost and cut but only 6 freuwncies for each band. The hi response is shelving rather than peaking because the inductor has been removed to save cost.


DIYers from beginner to expert have built this project.

Cheers

Ian

Thanks a lot Ian!
That's the kind of info I was looking for :)

Seems very tempting.

The optional tube gain: how important do you think that is for functionality and sound?
And how much will it add in cost to the project? (ok 5GBP for the pcb)
HJFP2, ssl9k, Harrison Ford Filters
My music

ruffrecords

Re: Poor Man's Pultec EQP1-A
« Reply #369 on: November 09, 2011, 04:59:21 AM »
Thanks a lot Ian!
That's the kind of info I was looking for :)

Seems very tempting.

The optional tube gain: how important do you think that is for functionality and sound?
And how much will it add in cost to the project? (ok 5GBP for the pcb)

The tube gain make up is simply a matter of taste (and cost). If you look around this site or at my profile you will see that I specialise in custom tube consoles. I don't do semiconductors, so any preference I might express would obviously be biased.

For functionality you do need a gain make up stage to make up the loss in the passive EQ but it can be solid state or tube based.

The tube gain make up , as well as the PCB, needs a tube (less than 15GBP), a mains transformer (probably 25GBP) and the diodes and capacitors in the supply circuit (say about 15GBP). I also do a PSU PCB.

Cheers

www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'


G-Sun

Re: Poor Man's Pultec EQP1-A
« Reply #370 on: November 09, 2011, 08:26:11 AM »
The tube gain make up is simply a matter of taste (and cost). If you look around this site or at my profile you will see that I specialise in custom tube consoles. I don't do semiconductors, so any preference I might express would obviously be biased.

For functionality you do need a gain make up stage to make up the loss in the passive EQ but it can be solid state or tube based.

The tube gain make up , as well as the PCB, needs a tube (less than 15GBP), a mains transformer (probably 25GBP) and the diodes and capacitors in the supply circuit (say about 15GBP). I also do a PSU PCB.

Cheers
Thanks!

Had a look at your site. Nice  :)

So, one more question about cost: To get the unit in the same ballpark as this http://www.recproaudio.com/diy_pro_audio/pultec_eqp1a.htm
( Sound wonderful I think)
How much would I need to add, getting better and more expensive components?
As you understand, I have little concept of what I would get for the budget-option mentioned above, compared to doing it all high-end.

Understanding the pultec eq: I was watching a video http://www.youtube.com/watch?v=uWbIAmLmdd8 and it seems like the fq on the unit are not really accurate. Like you dial in on 30hz and get something at 200hz. Is that right? Is this so for the high fq as well? Can someone enlighten me a little bit about this?

Thanks!
HJFP2, ssl9k, Harrison Ford Filters
My music

G-Sun

Re: Poor Man's Pultec EQP1-A
« Reply #371 on: November 09, 2011, 08:30:40 AM »
This might be the answer for my question:
http://www.gearslutz.com/board/6396212-post10.html
Is the Poor Man's Pultec EQP1-A replicating this behavior?
HJFP2, ssl9k, Harrison Ford Filters
My music

ruffrecords

Re: Poor Man's Pultec EQP1-A
« Reply #372 on: November 09, 2011, 03:14:48 PM »
Thanks!

Had a look at your site. Nice  :)

So, one more question about cost: To get the unit in the same ballpark as this http://www.recproaudio.com/diy_pro_audio/pultec_eqp1a.htm
( Sound wonderful I think)
How much would I need to add, getting better and more expensive components?
As you understand, I have little concept of what I would get for the budget-option mentioned above, compared to doing it all high-end.

The original EQP1A design you referred to above has a number of elements that were appropriate for the way equipment was used at that time.

First it was designed for use on a 600 ohm balanced circuit and its input transformer is 600:600. Today it is more common to use bridging inputs of 10K input impedance and the Poor Ma's EQP1A (PMEQP1A) uses a 10K:10K transformer for balanced inputs. Also today, some gear is operated unbalanced or electronically balanced and the PMEQP1A allows you to do this and save money. Neither of these changes affects the the way the EQ performs. Whether you use an input transformer or not, and if you do, which transformer you use, will inevitably affect the sound but not the way the EQ works.

Secondly, the original EQP1A it was designed to drive a 600 ohm output load at high power. This required using a push pull output and a phase splitter to drive it. In the original EQP1A both of these are achieved using transformers. Today we mostly drive 10K bridging inputs so the output power requirement is greatly reduced. We no longer need to use a push pull tube arrangement so we save the phase splitter transformer and some money. For the gain make up you can use a semiconductor amplifier or a tube based one. Both will have their own sounds but neither affects the way the EQ works. If you want a balanced output you can use a transformer with either a tube or semiconductor gain make up amp or use an electronically balanced semiconductor one. Again, these choices can affect the sound but not the way the EQ works.

Lastly, the PMEQP1A makes two compromises in the EQ to save cost. First we allow only 6 frequency selections because this allows us to use cheap 2 pole 6 way switches. Secondly, the hi boost EQ is modified to an RC shelving type instead of the resonant LC circuit in the original in order to save an expensive inductor. These are the only changes to the performance of the EQ.

So to answer your question, to get closer to the original does not necessarily make it  high end. That was the whole point of the PMEQP1A, to get as close as possible to the EQ peformance of the original at a fraction of the price. To build a replica of the original you are probably talking in the region of 1000GBP.

Quote
Understanding the pultec eq: I was watching a video http://www.youtube.com/watch?v=uWbIAmLmdd8 and it seems like the fq on the unit are not really accurate. Like you dial in on 30hz and get something at 200hz. Is that right? Is this so for the high fq as well? Can someone enlighten me a little bit about this?

Thanks!

Yes, this is a well known property of the original and creates what is known as the 'Pultec Bump'. It is not a question of the accuracy of the fq. There is no really accepted definition of fq for a shelving EQ although we have discussed that elsewhere on this forum. The fact of the matter is that to produce a curve that shelves at 30Hz you have to begin the boost at somewhere between 5 and 10 times that frequency. If you design so that the frequency at which boost starts is different to the one at which cut starts you can get interesting effects by boosting and cutting together. The original EQP1A went further by introducing a deliberate interaction between the lo boost and cut controls such that the cut becomes less effective as the boost is increased. This is what causes the Pultec bump and the PMEQP1A does exactly the same thing.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

rmaier

Re: Poor Man's Pultec EQP1-A
« Reply #373 on: November 09, 2011, 11:23:38 PM »

[/quote]
 I also do a PSU PCB.

Cheers
[/quote]

I had no idea you did a PSU PCB as well. I was under the impression everyone was perf-boarding their own and that you were only selling the EQ boards and tube makeup gain stage boards. Do you offer your PSU boards for sale, Ian?

Cheers,

Ralph
"Even if you don't know where the destination is of the sounds that you originate, it's worth getting it right at the start." - Rupert Neve

G-Sun

Re: Poor Man's Pultec EQP1-A
« Reply #374 on: November 10, 2011, 02:48:03 AM »
Thanks a lot Ian!
This looks like an affordable and nice build.

So, the choices are basically:
- Input transformer, or not
- Output-transformer, or not
- Tube-gain, or ss
? Right
What's the cost of a descent transformer?

Is it possible to do a stereo? 2 ch in 2 U rack?

Yes, accurate wasn't the right word, but the fq-labeling seems a little confusing when not knowing the unit :)

Hey: The forum-quizz dissappeared. Have I pased the intro-mark?  ;D
HJFP2, ssl9k, Harrison Ford Filters
My music

ruffrecords

Re: Poor Man's Pultec EQP1-A
« Reply #375 on: November 10, 2011, 04:57:19 AM »

Quote
I also do a PSU PCB.

Cheers

I had no idea you did a PSU PCB as well. I was under the impression everyone was perf-boarding their own and that you were only selling the EQ boards and tube makeup gain stage boards. Do you offer your PSU boards for sale, Ian?

Cheers,

Ralph

Yes, I have a few left over from an earlier project of mine. They were not designed specifically for this project. I can let you have one for 8GBP plus the usual 3GB post and Payapl costs.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

ruffrecords

Re: Poor Man's Pultec EQP1-A
« Reply #376 on: November 10, 2011, 05:02:29 AM »
So, the choices are basically:
- Input transformer, or not
- Output-transformer, or not
- Tube-gain, or ss
? Right

Correct

Quote
What's the cost of a descent transformer?

Good transformers start at around 40GBP and keep on going up and up  ;)

Quote
Is it possible to do a stereo? 2 ch in 2 U rack?

I deliberately made the EQ and tube gain make up PCBs slim enough to fit in a 1U case. I believe several people are building stereo EQs in 1U rack mounting cases.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

G-Sun

Re: Poor Man's Pultec EQP1-A
« Reply #377 on: November 10, 2011, 07:05:45 AM »

I deliberately made the EQ and tube gain make up PCBs slim enough to fit in a 1U case. I believe several people are building stereo EQs in 1U rack mounting cases.

Mmm.. Excellent :)
HJFP2, ssl9k, Harrison Ford Filters
My music

rmaier

Re: Poor Man's Pultec EQP1-A
« Reply #378 on: November 10, 2011, 11:12:26 AM »

Quote
I also do a PSU PCB.

Cheers

I had no idea you did a PSU PCB as well. I was under the impression everyone was perf-boarding their own and that you were only selling the EQ boards and tube makeup gain stage boards. Do you offer your PSU boards for sale, Ian?

Cheers,

Ralph

Yes, I have a few left over from an earlier project of mine. They were not designed specifically for this project. I can let you have one for 8GBP plus the usual 3GB post and Payapl costs.

Cheers

Ian

Excellent. Just Paypaled you. Thanks.
"Even if you don't know where the destination is of the sounds that you originate, it's worth getting it right at the start." - Rupert Neve

G-Sun

Re: Poor Man's Pultec EQP1-A
« Reply #379 on: November 10, 2011, 11:15:59 AM »
If I'd go for a cheap option, leaving the transformers and tube, would it be easy to later upgrade the unit with those parts?
HJFP2, ssl9k, Harrison Ford Filters
My music


 

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