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Stuffing an Heresy I ? :/


DrTUBE

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Today afternoon, being alone at home, I could test my "fully stuffed" HERESY I at high loudness - relative to my small auditorium, of course :) - using the amplifiers that I designed among others for them :

 

LUvYJb-P1100328.jpg

 

These are OTL (Output Transformer Less) mono block amplifiers, able to give continuous 10W RMS @16R, with a 1Hz-200KHz bandwith @10W.

 

I can confirm that - considering the means implemented here - the result with "full stuffing" is rather satisfactory, in terms of box resonances cancellation in the low-mid / mid region, which tended to be "ahead" of the rest of the sound spectrum, overshadowing notably the bass extension offered by the OTL circuit.

 

Another benefit provided by the  full stuffing is the lowering of the Qtc of the enclosure, which improve the bass extension (not the level) and the transient response. 

 

That said, I'll have to make some measurements to check that effective Qtc lowering... I remember that in 2005, I measured a Qtc at circa 0.8 , the enclosure being factory stock, but I am unsure of the value, since I did not retrieved my notes... :( 

 

One of you knows the Qtc value of the Heresy I, by chance ?

 

Cheers,

 

 

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On 2/25/2021 at 10:07 AM, jimjimbo said:

So I guess I haven't been paying attention.....so now the recommendation is to use an "E" network as is, rather than the "B"?

It depends on whether or not you want to elevate the bass/midbass/lower midrange up by 3 db wihout raising the mid and tweeter. I told him to try that and he liked it. He thought the bass was as good as his Forte 1's. Mods have been tweaked before. I didn't do it myself and measure, but since he had the chance to do the mod incrmentally, he saw no need to go any further when he simply recapped the old values, without adding more and re soldering the wires on the T-2A. You may want to try it yourself and see if you like it better. Then report back.

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recently bought some heresy 2's.

Quick info:

Have to replace the pyle tweeters that were glued to the horns (De-120's arriving tommorow), 

Have a small tear in my woofer (planning for deltas unless something comes up)

Am open to the option of the port......but

I have fiberglass insulation and was wondering about the placement of it. it is the thinner roll kind. Not a full sheet and not as thick, maybe half the thickness.

Should I line the walls? U shaped around the woofer (thats what was in one of the speakers, other speaker the guy had a half assed eggshell foam of an attempt), subwoofer area only? leave wood exposed behind the woofer? Would try whatever, just curious what I should do. 

btw caps are brand new from bob crites annnnd I have a pair of tangent 500's which I am willing to entertain ideas too. Thats another thread.

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  • 5 months later...

I would like to thank DrTube for a most convincing presentation.  I used 2.5 pounds of fiberglass wall insulation in each speaker.  I gather the key is to heavily stuff the cabinet, light stuffing or half stuffing will not have much effect.  I also recapped with the economical Solen caps and added the 12 ohm resistor.  Also, moving the wires on the transformer taps 2 to 1 and 3 to 2 went a long way towards correcting the way too hot mid and tweeter balance.

 

Another change I made was to move the E-2 crossover to the outside back of the speaker.

 

Also, OTL tube amps rule them all.  I favor the Futterman and Mellow designs.

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Moving the crossover outside made the stuffing process easier and offset the volume of the stuffing some.  The inside would look similar to the OP pictures, except I used fiberglass which is the most economical stuffing and easily obtainable at the Home Depot.  I used one large piece wrapped around speaker interior.  

External X-over.jpg

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I've modeled my wires after the Nordost line.  They are 6 x 22 ga (14 ga) silver plated solid core PTFE teflon insulation in a widely spaced ribbon array.  Also using this for power cord (but not in a ribbon formation).  Very surprised this wire made such a huge difference, especially in the amp power cord.  I would like to thank Jeffrey Medwin for providing an excellent source for the wire:  https://www.apexjr.com/wire.html

 

Um, your iPhone has an irritating signature Sent from my iPhone, you should correct that.  How to Remove the “Sent from My iPhone” Signature

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  3. Scroll down a ways and then tap on “Signature”
  4. Tap “Clear”, or just select all the text and delete it manually.
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