anjing

Re: EZ Tube Mixer
« Reply #500 on: March 29, 2013, 10:49:49 AM »
@Pierre, Holger

Yes, the idea is these replace the Schroff  side cheeks. All you need to buy then is the various extruded rails. The cheeks are 3 mm thick so you can countersink the screws and butt them together. I thought of adding some tapped holes to make it easy to bolt them together.

I am thinking of using one inch wood for the cladding. The shape of the wood would be the same as the metal but extend downwards one extra inch  and mate with an inch thick rectangular sheet that forms the bottom of the mixer. There would also be a wooden rear panel above the XLRs and the woden cheek would also extend an inch at the top to mate with a wooden top piece and similarly extend and inch in front  of the fader section to mate with an arm rest.

Frank told me about his new machine. I think it could do  this job but I have not asked him yet.

Cheers

Ian

Much better then the way i did it! Great work Ian!

Regards!

Pierre


ruffrecords

Re: EZ Tube Mixer
« Reply #501 on: March 29, 2013, 12:25:51 PM »
Here's a link to the fpd file of the current design of the end cheek. This is slightly different to the one I posted earlier. The overall shape is the same but I have now added proper sets of holes for Schroff extrusions. The 9U sloped one and the small 3U one at the rear I have set up as macros so they can be used anywhere at any angle. They are probably not at the exact positions they need to be on this drawing but they are not far off:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/Mechanics/MK4cheekmetalv1.fpd

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: EZ Tube Mixer
« Reply #502 on: March 30, 2013, 09:47:17 AM »
I have just uploaded a schematic of the Twin Line Amp:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/twinlineamp/

The first sheet shows the input circuit and the second shows the two line amps. I have modified the heater wiring so that either 6922 or ECC99 tubes can be used in the output stages. The ECC99s are intended for using the board as a stereo headphones amp with external transformers. Unfortunately the ECC99 has  a different heater arrangement to the 6922 so I have had to add some extra links so the heaters can be configured for each tube type. These are shown on sheet 3 of the schematic. Note that you have to use either a pair of 6922s or a pair of ECC99s, you cannot have one of each.

The line amp with 6922s will drive headphones down to about 400 ohms with the normal 2:1 output transformer. For lower impedance headphones you need the ECC99s and a different ratio transformer. For the ultimate in flexibility and quality you can use the Sowter 8665 transformer but it is rather expensive. For 30 to 60 ohm headphones you can use the much cheaper Edcor XSE 10-50-8K.

I will be putting together a document showing the component changes necessary to use the ECC99s.

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: EZ Tube Mixer
« Reply #503 on: March 30, 2013, 12:34:43 PM »
I sent my MKIV cheek design to Frank Roller to check that his machine is big enough to do a sheet this size. He emailed me to say his machine is fine but his normal material size is no bigger than 500mm by 500mm so he would have to order in some larger sheet. No problem in principle, but I thought it might be interesting to see just what cheek shapes we could get out of a 500mm by 500mm sheet. So far I have come up with two designs both of which are posted here along with the MKIV, all in fpd format:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/Mechanics/cheeks/

The 500 is 500mm deep and 500mm high. I managed to squeeze in a 6U sloping section and a 3U meter bridge but there is no room at the back for anything other than connectors and transformers - no extra amps as in the MKIV. The MINI is the same as the 500 but without the meter bridge.

The MINI costs about 80Euros, the 500 about 100 Euros and the MKIV about 140 Euros.

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'

shabtek

Re: EZ Tube Mixer
« Reply #504 on: March 30, 2013, 12:45:21 PM »
ahh...Cheek...now you are speaking my language. ;D



nice work Ian.
"really fine players do not use stomp boxes or master volume, they match the amp to the room and turn it up to 11.  Stevie Ray, BB King, Albert King, Duane Allman, Dicky Betts, Louis Armstrong"
   -CJ

KMB-AUDIO

Re: EZ Tube Mixer
« Reply #505 on: March 30, 2013, 01:14:48 PM »
@KMB-AUDIO - Do you know what you're buying from 8020.net? Is there a certain part#? I ask as I've been on their site before and didn't necessarily find something off the shelf that had all the tapped holes. I can say that I didn't extensively look tho.

Thanks gentlemen,
Dave

Hi Dave,

I was looking at either the 10, 15, 20 or 25 series: http://8020.net/T-Slot-5.asp. With these profiles, you use a captured nut to tighten the panels down. I haven't given the frame enough thought yet, but it seems like these profiles might work.  Prices seem reasonable too.

I also found a supplier in the US for eurocard subracks: http://www.pixustechnologies.com/products/components/rails-and-card-guides/ I'm going to contact them to see what they can provide.

« Last Edit: March 30, 2013, 01:19:00 PM by KMB-AUDIO »
Call me Matthew.

shabtek

Re: EZ Tube Mixer
« Reply #506 on: March 30, 2013, 01:29:35 PM »
I have a few spare sets of schroff rails.
can someone tell me if Ians Backplane mounts to the 'standard rail'--i.e. -could- line-up and be affixed to the front of the subrack?
or does it require the z-rail part?

I gather it screws down to the standard rail, and the z-rail is used only to mount din connectors without a backplane.

Pierre can you verify this, as you have done both?
« Last Edit: April 02, 2013, 11:22:41 PM by shabtek »
"really fine players do not use stomp boxes or master volume, they match the amp to the room and turn it up to 11.  Stevie Ray, BB King, Albert King, Duane Allman, Dicky Betts, Louis Armstrong"
   -CJ

ruffrecords

Re: EZ Tube Mixer
« Reply #507 on: April 03, 2013, 03:55:22 PM »
I have a few spare sets of schroff rails.
can someone tell me if Ians Backplane mounts to the 'standard rail'--i.e. -could- line-up and be affixed to the front of the subrack?
or does it require the z-rail part?

I gather it screws down to the standard rail, and the z-rail is used only to mount din connectors without a backplane.

Pierre can you verify this, as you have done both?

It is easy to tell the difference. If your rear rails have a slot for a nut strip or have a nut strip slid into them then they are definitely the backplane type. If they have a sort of dog leg with tapped holes in it then they are for direct mounting of connectors i.e NOT for backplanes. The Z-strip tacks onto a backplane type to make it into a dog leg.

Hope that makes sense.

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'

anjing

Re: EZ Tube Mixer
« Reply #508 on: April 03, 2013, 05:32:16 PM »
I have a few spare sets of schroff rails.
can someone tell me if Ians Backplane mounts to the 'standard rail'--i.e. -could- line-up and be affixed to the front of the subrack?
or does it require the z-rail part?

I gather it screws down to the standard rail, and the z-rail is used only to mount din connectors without a backplane.

Pierre can you verify this, as you have done both?

Hi Shabtek,

   It seems that without the rack fillers the my spare backplane would fit in the front rail of my 3u fader buckets. With the rack ear fillers i can't fit it flush with the sidcheek but  if i hold it up, all the wholes line up. Using 12mm long screws works. I could take a pic tommorow.
Newark has the z-rails, they have a month delivery time.

Hope this helps,

Pierre


shabtek

Re: EZ Tube Mixer
« Reply #509 on: April 03, 2013, 08:13:05 PM »
many thanks fellas
"really fine players do not use stomp boxes or master volume, they match the amp to the room and turn it up to 11.  Stevie Ray, BB King, Albert King, Duane Allman, Dicky Betts, Louis Armstrong"
   -CJ


G-Sun

Re: EZ Tube Mixer
« Reply #510 on: April 04, 2013, 03:54:53 AM »
Awesome project!
Keep on rolling guys :)
HJFP2, ssl9k, Harrison Ford Filters
My music

anjing

Re: EZ Tube Mixer
« Reply #511 on: April 04, 2013, 05:27:27 AM »
I have a few spare sets of schroff rails.
can someone tell me if Ians Backplane mounts to the 'standard rail'--i.e. -could- line-up and be affixed to the front of the subrack?
or does it require the z-rail part?

I gather it screws down to the standard rail, and the z-rail is used only to mount din connectors without a backplane.

Pierre can you verify this, as you have done both?

Thinking back we have to consider the dept as well...here is the data for the backplane rail i am using, you can compare the measurment with the ones you have....

KMB-AUDIO

Re: EZ Tube Mixer
« Reply #512 on: April 05, 2013, 07:22:41 PM »
So I've been thinking about how I use my current console and how I would like to route the signal this mixer.  I've come up with the following block diagram so far (attached). 

The relay board will be mounted on the back panel near the tape/line inputs. 

I have a few questions:
1. Is a 600:600 transformer appropriate for the main/aux outs? I have some carnhill and edcors sitting around that I would like to use at some point.

2. How much loss am I going to experience from the EQ (to the aux sends)? My main reason for making the EQ the first thing after the input transformer is because of my desire to have a Pre-Fader/Post-EQ Aux option. I figure the combining aux amps could make up for any gain loss...or would it be better to have the signal route like: transformer>EQ>First Amp Stage>Fader, and take the Pre-Fader/Post-EQ send after the first amp stage?

3. Anybody see any glaring issues with this?
Call me Matthew.

ruffrecords

Re: EZ Tube Mixer
« Reply #513 on: April 05, 2013, 08:05:00 PM »
So I've been thinking about how I use my current console and how I would like to route the signal this mixer.  I've come up with the following block diagram so far (attached). 

The relay board will be mounted on the back panel near the tape/line inputs. 

I have a few questions:
1. Is a 600:600 transformer appropriate for the main/aux outs? I have some carnhill and edcors sitting around that I would like to use at some point.

2. How much loss am I going to experience from the EQ (to the aux sends)? My main reason for making the EQ the first thing after the input transformer is because of my desire to have a Pre-Fader/Post-EQ Aux option. I figure the combining aux amps could make up for any gain loss...or would it be better to have the signal route like: transformer>EQ>First Amp Stage>Fader, and take the Pre-Fader/Post-EQ send after the first amp stage?

3. Anybody see any glaring issues with this?

I am not sure what is going on with your AUX source selection but you seem to have three of them. One appears to be pre-EQ, the next pre-fader and the last post fader. Is that what you really intend?

The post fader sends need to be driven from the amp output to ensure a low impedance source for the mix buses. The pre-EQ source is the transformer and provided your signal source is low impedance this should be OK. The pre-fader connection you have unfortunately will not work as the EQ output impedance is too high. If you really want a post EQ/pre-fader signal you need to do it after the EQ gain make up amp (between the two amps in your diagram) as you suggested.

You can use a 600:600 transformer provided your load is 10K bridging. If you need to drive a 600 ohm load you should use a 2K4:600 transformer and tweak the gain up by 6dB.

The AUX master faders should be before the bus amps just like you have for the L/R bus.

The twin line amp PCB only contains two amps and two transformers so if you use both in a channel, 16 boards will get you 16 channels rather than 32.

The normal configuration would be Transformer->prefadeAuX/EQin... EQout->fader->amp->postfadeAUX/pan

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'

KMB-AUDIO

Re: EZ Tube Mixer
« Reply #514 on: April 05, 2013, 09:22:54 PM »
Thanks for pointing that stuff out, I've revised the diagram. I can live without a Post-EQ/Pre-Fader send.

The signal source for the input is my DA converters, they should be sufficiently low enough to drive the aux sends, but I'll have to double check.

The 600:600 for the main outputs should be ok, but I can't guarantee that I'll always be driving a 10k bridging input on the aux sends.

How does this look?
Call me Matthew.

ruffrecords

Re: EZ Tube Mixer
« Reply #515 on: April 06, 2013, 03:37:20 AM »
That is spot on. You even corrected my mistake by correctly placing the fader before the EQ.

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'

analag

Re: EZ Tube Mixer
« Reply #516 on: April 06, 2013, 06:20:21 AM »
I have just uploaded a schematic of the Twin Line Amp:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/twinlineamp/


What's the input swing capability of this line amp. Can it handle even a 2V swing?
Audio engineering suffers from misinformation, disinformation, and downright lying more than most fields of endeavour.

ruffrecords

Re: EZ Tube Mixer
« Reply #517 on: April 06, 2013, 06:51:28 AM »
I have just uploaded a schematic of the Twin Line Amp:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/twinlineamp/


What's the input swing capability of this line amp. Can it handle even a 2V swing?

Depends on the gain setting but at 6dB gain it can easily handle +20dBu

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: EZ Tube Mixer
« Reply #518 on: April 06, 2013, 06:53:46 AM »
That is spot on. You even corrected my mistake by correctly placing the fader before the EQ.

Cheers

Ian

I forgot to say that if you are going to drive a load less than 10K the you really ought to use a 2K4:600 output transformer.

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: EZ Tube Mixer
« Reply #519 on: April 13, 2013, 08:08:04 AM »
I have just been reading John Roberts excellent old article on mixing and I was especially interested in his description of the Transamp because the topology is very similar to that used in the Eurochannel card. The basic idea is that the gain of the first stage is altered by the feedback network  gain setting resistor so the open loop gain varies with the closed loop gain keeping the amount of NFB fairly constant thus significantly aiding stability.

It was not until later in the article when John was discussing the advantages of the Transamp in virtual earth summing that it occurred to me that the Eurochannel might be used in exactly the same way. You would short the normal input and feed the bus into the 100uF gain setting capacitor. In theory, as you add more channels to the bus, the open loop gain increases and again the amount of NFB remains much the same and mix bus stability problems are eased.

I thought I would try simulating this and to be honest I expected it to work for small numbers of channels but to run out of steam for higher numbers. I tried one input and then 10 inputs and it was OK so I kept on going. To cut a long story short I kept going up to 40 inputs and it was still fine. I had all 40 inputs set to -4dBu all at the same frequency and got the expected output of +28dBu with a distortion of just under 0.2% into a 2400 ohm load.

I need to check this works with real hardware but is does look promising.

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'


 

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