Should I?

I always mount heatsinked parts isolated to the heatsink - since I want to touch the heatsink without any danger ... :grin:

[quote author="tommypiper"]I was also wondering about the heatsinks being close to caps.

And the two large heatsinks almost touching. Are they the same
potential, or would it be a problem if they touched?[/quote]

The two heatsinks are not at the same potential. And if insulators are used, then they should be at no potential...which is ultimately safer for the builder.

These tubes will run no hotter than they do in the Altec 4xx type.

analag

It works! :green:

:thumb: :thumb: :thumb:
I never doubted
:green: :green: :green:

Hey guys,

delighted to hear that the pcb protos are passing audio! As a general question to Analag and you guys - does this design have a time constant switch with fixed ratio attack and releases or is it possible to bring them out on separate controls? I'm sure I'll have a better idea when I receive the schematics and boards but I'm just passing the time.

Very excited about this project.
:guinness: for everyone's work and Analag's generousity of spirit.

Cheers,
Ruairi

Adjustable threshold and release is what you get. Remember this is the Poor Man's version of the 660, obviously some things were streamlined.


[quote author="[silent:arts]"]:thumb: :thumb: :thumb:
I never doubted
:green: :green: :green:[/quote]

I know.

analag

[quote author="ioaudio"]i still wonder about the measurements done by volker
XSM 10k:10k seem to roll off the high frequencies a lot , i mean - 1 or 2 dB @ 20kHz can be wonderful, but - 6dB?[/quote]

The Edcors are doing a very good job in this circuit


regards
Bernd

Had a glance, don't see it addressed; why the XSM series for input, and is it necessary for output too? Would WSM series be fine for both? Tried both, and it's a taste thing? What? Any commentary?

do a search for XSM and analag:
[quote author="analag"] The quality and inductance range of the XSM lineup is better than the WSM from my experience and I have almost (30) Edcors in use here in my studio[/quote]
the specs are 600:10K at the input, 10K:600 for the output, the same in the sidechain.
everybody is free to use the transformers he want, but we won't check them all for you - since the XSM work fine here :grin:

That's a tough quote to find in 17 pages of stuff. Okay, then please address the output level required - is the WSM sufficient in that regard? The chart looks quite fine. I just happen to have a pile of the WSM types already, and they do spec better 'on paper'. Inductance may well be an issue with this design. Any reason you guys feel the need to order 600:10K and 10K:600 versus all of one? Trying to mix it up? They are the same thing as far as I can tell.

my fault, sorry. should have said "search for XSM and Author = analag".

to make things short: analag used this transformers in this combinations, and it worked out well. why should we (beta testers) use other combinations.

if someone is willing to send me other transformer models etc, I'm wiling to test and measure them in the circuit. but there is no way I will buy them all.

you can build it DBM (do it by numbers, what we mostly do with the prototypes), or DIY.

since I have two WSM 600/10K at home, I can do a little test for you once my prototype is up and running :thumb:

that measurement surely looks better. any explanataion for the sudden fall of thd@10khz ?

doug,

the difference WSM and XSM is the core size
higher level with the xsm, but also higher leakage inductance&capacitance (bigger bobbin)

high res

Cool, thanks. I'm sure the question is of interest to others. Love to see some charts and hear some commentary comparing them directly.

I have both types, and am well aware of their quoted specs. I'd just like to see a thorough diagnosis of why the XSM type is preferred here, especially in regards to the input. Very few people even need the +27 dBm input handling of the WSM, much less what the XSM can handle, and the quoted response is better with the WSM. Handling of DC in the output core could be one reason; we don't have a circuit to examine yet. Does the side to side resistance variation appear better in the XSM's, or does it matter here? The ones I've measured don't look terribly well balanced in regards to resistance, and it may well not matter.

It certainly ain't about the $ :razz:

Hwyl Lads,

My hat is tipped for you chaps, absolutley spot on !
Well done !

Iechyd Dda (cheers)

Steve

I'm sure something other than XSM can be used for input, I chose XSM for the output because of a number of reasons. DCR which is lower because of bigger wire, which translates to lower voltage drop and higher current carrying capacity and to a lesser degree, less effect from DCR imbalance, core size which is always a plus when DC flows through a transformer even though the pushpull action nullify the effect, higher inductance and it costs only $2.00 extra.

The unbalance in P-CT-P across the primary, is not a problem. What we need is inductance balance from P-CT-P which we have.

I'm curious to see how all these measurements compare to my own.

analag

Slightly off topic - do transformers have to be gapped to carry DC or is that just for single ended amp outputs like Neve BA283 etc.Reading between the lines from analogs last post - is the XSM 10K:600 a suitable candidate for the output of a Chiswick Reach clone as in this topic
http://www.groupdiy.com/index.php?topic=11814&highlight=chiswick
Sowter iron sure is nice but at £70 per output does strain the pocket :!:

[quote author="Larrchild"]I guess this question should go to Silent Arts. Is it possible that the 2 left-side tubes are so close to the 2 10uf Wima caps that they will heat the caps unnecessarily? ...[/quote]
Larrchild, some news: the WIMAs get a bit hot, but within the WIMA specs:

did some wiring today, the first channel is working with no problems :green:

Volker, I was thinking that if the heat was ever of concern, a rectangular aluminum plate between the tubes and caps mounted on some standoffs would make an excellent "firewall" without any board changes.

When the unit is fully enclosed another test should occur.=)

Hi there,
we are near completion of the prototypes. I found some time to play the piano (steinway grand) and recorded an improvisation (impressionistic style) of a famous children folksong (Hänschen klein) and compressed it with the PM670 prototype. Damn, this boy has character. What it does to the sustain and especially to the "Forte" part in the middle is simply incredible. Try to make an A/B comparison and you´ll realize the rich sound and the body that is added by the PM670.
Enjoy the project, enjoy the music!!

Waveforms


stereo wav file untreated (12,5 MB)
http://groupdiy.silentarts.net/PM660/bernd/steinway.wav

stereo wav file pm670 (12,5 MB)
http://groupdiy.silentarts.net/PM660/bernd/PM670steinway.wav

regards
Bernd

Holy Folk!

I'm sitting in a hotel room listening on the mono speaker of my Macbook Air and even on that the difference is massive. I love what it's doing to the character of the piano. I was seriously excited about this project before but now I just can't wait to get cracking.

Beautiful piano playing BTW, I've listened to it 6 or 7 times in a row.

:thumb: :guinness: :thumb:

How much gain reduction is happening?

Cheers,
Ruairi