DCPP
Yes, but,
I need a little gain as my current source is low level and doesn't drive the DCPP properly.
I'm thinking about the Mezmerize
Mezmerize B1 Buffer Preamp
Yes, but,
I need a little gain as my current source is low level and doesn't drive the DCPP properly.
I'm thinking about the Mezmerize
Mezmerize B1 Buffer Preamp
How much gain do you need? if something like 3X~6X will work, I would do Salas' 6V6 line preamp 🙂
Yes indeed, Salas’ 6V6 is definitely on the list.
I was thinking though that I could knock up a Mezmerize quite quickly as the 6V6 will no doubt take me a lot longer.
I was thinking though that I could knock up a Mezmerize quite quickly as the 6V6 will no doubt take me a lot longer.
Nice. Could you let me know what heat sink you used? Is it effective? My DCPP doesn’t have a sink and it gets HOT - so I ended up using active cooling with a small fan running at low speed.
Tristan
It's an AAVID THERMALLOY 3.5Y-1
https://uk.farnell.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&langId=44&urlRequestType=Base&partNumber=170088&storeId=10151
To be honest, my whole top plate gets hot but it seems to be from the power transformer rather than the heatsink which is notably cooler than the transformer.
My B+ is running higher than standard at 385V, I don't know if that's why my power transformer is getting hot.
It's not too hot to touch but it feels as hot as a central heating radiator....
https://uk.farnell.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&langId=44&urlRequestType=Base&partNumber=170088&storeId=10151
To be honest, my whole top plate gets hot but it seems to be from the power transformer rather than the heatsink which is notably cooler than the transformer.
My B+ is running higher than standard at 385V, I don't know if that's why my power transformer is getting hot.
It's not too hot to touch but it feels as hot as a central heating radiator....
Andy congratulations for your build. If you ever dismount the heatsink, clean the thermal paste and apply less so it doesn't come out at the front. Or maybe you can clean it with a tissue and some alcool. Otherwise it looks great !
As for your high B+, I had the same issue and it was a defective B+ ripple filter. See my previous posts, you should have about 20V over it. You can measure it between the "south" pin of R21 and one of OPT central tap. Less risky than on the Q2 FET close pins. On mine, it was an open R69 but I guess the issue could be at D9 or Q2 as well.
As for the preamp, see these posts :
no direct experience with them yet but others seem to like them. I have an Aikido from John Broskie to build but not done yet either, that's in the queue for the next weeks.
As for your high B+, I had the same issue and it was a defective B+ ripple filter. See my previous posts, you should have about 20V over it. You can measure it between the "south" pin of R21 and one of OPT central tap. Less risky than on the Q2 FET close pins. On mine, it was an open R69 but I guess the issue could be at D9 or Q2 as well.
As for the preamp, see these posts :
no direct experience with them yet but others seem to like them. I have an Aikido from John Broskie to build but not done yet either, that's in the queue for the next weeks.
I had the same 'issue'. Th Edcor PT got very hot, probably well within spec but it made me a little nervous. So I ended up getting a custom PT made by Toroidy with the same windings but for 50Hz and a little more capacity. I also got a thicker top-plate made with vents. Much, much cooler running, especially with the fan. But I'm always looking for ways to go back to passive cooling.
Attachments
I love these short and thick Compactron tubes and their large number of types for the same application! What a pity that they, and their sockets, appear to be almost unobtainable here in Europe, and if they were, they're certainly not on the one bucks list 🙁.
Best regards!
Best regards!
I purchased the engineers amplifier PCB in 2013 and finally built it. There is a front panel express .fpd file on Pete Millet’s webpage but Pete said on the site that he was not sure if it’s correct. Has anyone used this file to get a top chassis made, or can you share a file known to be correct?
Thanks
Thanks
I think I may have been the person who created that .FDP file originally. I used it in my own build and the only issue I had was I ended up using thinner sides because of spacing around the perimeter.
-D
-D
Here's are a couple of files I used. I took the autocad file, imported to FPE and edited it to what I needed (moved the IEC inlet / audio inputs to a rear panel). As far as I remember all the dimensions for the PCB mountings were correct, as were the transformer holes. Rename the flies from .txt to .fpe.
Power-Top.txt is my first version using all Edcor transformers, _2 is a 2nd version using a toroidal PT.
T
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Here's a link to the fpd Pete sent me directly when I built my amp a few years back. It worked perfectly.
DCPP.fpd - Google Drive
Attached are the two .FPD files I used in my build (you'll need to rename them). Here's a shot mid-build:
Underside shot:
Final version (prior to staining):
Note: I used a different power inlet than Pete used (it's a Corcom - can't recall the part number - that I picked up at a surplus shop).
Good luck!
Underside shot:
Final version (prior to staining):
Note: I used a different power inlet than Pete used (it's a Corcom - can't recall the part number - that I picked up at a surplus shop).
Good luck!
So, only 11 😱 years after buying the pcb for this I finally built the amp.
I fired it up last night for the first time and got the bias dialed in and tonight was the first time I hooked it up to a decent pair of speakers. I'm listening to it with some Dynaco A25s and it sounds pretty sweet.
Its a stock build using the specified Edcor iron, I screwed a 3" x 4" x 1/4" copper plate to the bottom of the top plate as a heatsink, seems to work great, its only a little warm to the touch.
The only issue I have is the power transformer is producing a minor hum that can also be heard in the speakers, and its also running a little hot. It was worse when I had it plugged in at my workbench on a normal power strip with some old Klipsch PC satellite speakers. I have it plugged into an isolation transformer now and it is humming slightly less. If I put my ear against the speaker I can hear the hum but nothing at normal listening distance with the Dynacos.
I fired it up last night for the first time and got the bias dialed in and tonight was the first time I hooked it up to a decent pair of speakers. I'm listening to it with some Dynaco A25s and it sounds pretty sweet.
Its a stock build using the specified Edcor iron, I screwed a 3" x 4" x 1/4" copper plate to the bottom of the top plate as a heatsink, seems to work great, its only a little warm to the touch.
The only issue I have is the power transformer is producing a minor hum that can also be heard in the speakers, and its also running a little hot. It was worse when I had it plugged in at my workbench on a normal power strip with some old Klipsch PC satellite speakers. I have it plugged into an isolation transformer now and it is humming slightly less. If I put my ear against the speaker I can hear the hum but nothing at normal listening distance with the Dynacos.
Attachments
So I've been thinking about this amp, and re-reading Pete's adjustment procedure. He mentions that the bias pots come from the factory turned all the way down and the balance pots are centered.
What I remember when I started the adjustments last night was that the bias pot was centered and the balance pot was all the way counterclockwise.
So I think what I may have done is installed them in the wrong positions so I have 5k pots where there are supposed to be 10k. Could this have any adverse effects if all the tubes biased up correctly?
I think I'm going to take it apart tomorrow and pull the trimpots out and check them out of circuit just for peace of mind.
What I remember when I started the adjustments last night was that the bias pot was centered and the balance pot was all the way counterclockwise.
So I think what I may have done is installed them in the wrong positions so I have 5k pots where there are supposed to be 10k. Could this have any adverse effects if all the tubes biased up correctly?
I think I'm going to take it apart tomorrow and pull the trimpots out and check them out of circuit just for peace of mind.
Hi Coreyk78, good to see your project getting done... as for the pots, the bias value is important so be sure the pots can bring you the desired value of 0.4V across the measuring resistances as described in the "Adjustments" chapter. My original amp needed days to stabilize the tubes current, and after a few weeks one tube developed "cracking" and needed to be swapped out. No problem since then (~ 2 years). I have a 2nd such amp in the workshop on Toroidy PT and OPTs, more within a few days.
About the hum : I have a similar problem, in my opinion the original Edcor PT is somewhat at its limits, this is why I went for Toroidy for the 2nd model, and I will replace the PT of the 1st build if things go well. Simply too much mechanical noise on my 235V wall power.
I had another issue, a defective voltage regulation, see my post #1638. That caused 100Hz hum due to passing PSU ripple unfiltered through the FET regulation. You can use a free spectrometer app on your smartphone to identify the hum frequency, I have had issues to distinguish 50 from 100 Hz with only my ear... put it on lack of experience.
About the hum : I have a similar problem, in my opinion the original Edcor PT is somewhat at its limits, this is why I went for Toroidy for the 2nd model, and I will replace the PT of the 1st build if things go well. Simply too much mechanical noise on my 235V wall power.
I had another issue, a defective voltage regulation, see my post #1638. That caused 100Hz hum due to passing PSU ripple unfiltered through the FET regulation. You can use a free spectrometer app on your smartphone to identify the hum frequency, I have had issues to distinguish 50 from 100 Hz with only my ear... put it on lack of experience.
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