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Old 25th April 2012, 03:34 PM   #291
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Quote:
Originally Posted by KSTR View Post
See below sim for the effect of a detuned Howland in the MyRef. Detuning is by setting one resistor to -2%, 0% and +2% of its nominal value, giving the pump different output impedances, including negative.
Thanks - I'll try to wrap my mind around this, haven't fully digested it. The one thing I'd like to simulate is the output Z with very slightly mismatched (say 0.1%) resistors in the pump network. The closed-form expression for Zo was in your earlier reference (from Apex), but here we don't actually know the exact open-loop gain of the chipamp, just an approximate gain number from the datasheet for the LM3886.

I'll plug in the LM1875 model for the chipamp and play around with it later.
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Old 25th April 2012, 05:22 PM   #292
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Hey Dario, Where are the latest top choices for the FE - the Mouser BOM or a shared Google Docs folder (that I can't find)?
Hi Bob,

https://docs.google.com/spreadsheet/...POWJjTEE#gid=0

You should have the link to the complete folder in one of earliest emails to beta testsers

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I'm about to put in the PRPs in R104/204 and I have some 68Rs for C101/201, but the Caddocks will probably win out. Four Elna Cerafine caps (100uf/35V) are on hand for C102/202.
PRPs, while fine, are a bit too harsh in that positions I largely prefer KOA PR1 and best Caddocks MP915.

The four Cerafines have a very nice timbre and dynamic but they introduce, I discovered later, a tiny bit of HF harshness.

Now I prefer FGs there.

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Also, you mentioned several more items will be surface mount on the final PCB. Will it be possible and/or worth the effort to adapt those changes to the beta boards?
Probably not.

The through hole conterparts, though, are way more costly than the best SMDs I've selected.
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Old 25th April 2012, 07:12 PM   #293
bcmbob is offline bcmbob  United States
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Thanks D, I have that link but thought there might be a separate FE folder somewhere - not so. I'll compare what I have and order the new items for review.

Have you had the opportunity to listen to the True Copper caps for C13. From what I can see they are ~$30 US and would be the most expensive part of the amp.

I'll have to sharpen my component extraction skills for the parts transfer when the new board is available.
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Old 27th April 2012, 12:48 AM   #294
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I may be jumping the gun, no actual burn-in yet, but the Elna Cerafines in C102/202 sound great. My first impression is like moving 8 to 10 rows closer to the stage - resulting in the perception of the band being wider and the instruments more easily defined. All these upgrades are producing both improved punch where it belongs and overall smoothness without sounding forced or fake. Musical indeed!

I'm starting to feel like someone being led around by the Pied Piper, but Dario is truly making some valid and productive recommendations. I will try the other Caddocks and the FGs next after these have marinated.
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Old 27th April 2012, 01:03 AM   #295
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Just have to mention - I'm hearing lots of wind instrument players taking breaths.... SWEET!!
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Old 27th April 2012, 02:34 AM   #296
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Have you had the opportunity to listen to the True Copper caps for C13. From what I can see they are ~$30 US and would be the most expensive part of the amp.
Not yet, in this moment Intertechnik has production problems and most values are not available...

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I'll have to sharpen my component extraction skills for the parts transfer when the new board is available.
Apart the obvious desoldering station, I usually put more solder on the joint and while heating it I gently pull the component but you can do that only with parts not too sensitive to heat.

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Originally Posted by bcmbob View Post
I may be jumping the gun, no actual burn-in yet, but the Elna Cerafines in C102/202 sound great.


Quote:
Originally Posted by bcmbob View Post
I'm starting to feel like someone being led around by the Pied Piper, but Dario is truly making some valid and productive recommendations. I will try the other Caddocks and the FGs next after these have marinated.
Thanks.

If you want to speed up burn-in I suggest you to buy the Isotek Full system Enhancer.

One or two plays of the second track and quite all components are full burned-in.

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Just have to mention - I'm hearing lots of wind instrument players taking breaths.... SWEET!!
Did you installed them with sockets? If so try to pull them out...(the amp must be powered off, obviously )
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Old 27th April 2012, 04:50 PM   #297
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Hey Dario,

I bit the bullet and bought two True Copper 1.2uF caps. No non-stock warnings yet.

Have you tried the low temp Chip-Quick solder.

Not sure about the Enhancer CD. Sounds like snake oil to me. Seems like a few plays of The Rite of Spring and a cover of a couple "Weather Report" disks would do the same thing.

I ran out of sockets but they are in the Mouser order placed today.
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Old 27th April 2012, 05:01 PM   #298
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I bit the bullet and bought two True Copper 1.2uF caps. No non-stock warnings yet.
I know... a little birdie said to me...

I did the same this morning...

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Have you tried the low temp Chip-Quick solder.
No but I've tried the desoldering alloy, incredibly good.

You could use it to desolder also th parts.

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Not sure about the Enhancer CD. Sounds like snake oil to me.
I was skeptical too... I've read about it on the italian forum VideoHiFI

One forumer I trust recommended it and I choose to try.

It works and it's effective.

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I ran out of sockets but they are in the Mouser order placed today.
Fine
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Old 27th April 2012, 05:18 PM   #299
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Originally Posted by bcmbob View Post
Hey Dario,

I bit the bullet and bought two True Copper 1.2uF caps. No non-stock warnings yet.

Have you tried the low temp Chip-Quick solder.

Not sure about the Enhancer CD. Sounds like snake oil to me. Seems like a few plays of The Rite of Spring and a cover of a couple "Weather Report" disks would do the same thing.

I ran out of sockets but they are in the Mouser order placed today.
Amazon.com: XLO/Reference Test & Burn In: Xlo Reference Recordings, Various Artists: Music
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Old 27th April 2012, 05:24 PM   #300
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Suburra told me it works too but when he tried the Isotek he had more immediate and directly audible results.
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