IVY III tweaking for warmer sound - diyAudio
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Old 1st August 2014, 03:51 PM   #1
sbelyo is offline sbelyo  United States
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Default IVY III tweaking for warmer sound

I just finished my BIIIse with IVY III output stage. I am only using the single ended output for now as my balanced amp in no where near being finished.

After about 8 hours of listening I feel that the resolution and level of detail is excellent perhaps even exceptional compared to anything I've built or modded to date.

However, the DAC seems bright and missing some low end. I tried it with my Dynahi 1.0 and my BH Crack. The crack tames it somewhat but it's still bright. Headphones used were HD650 and Headphile Darth Beyers V2 (Bass heavy). I intend to give it at least 100 hours of burn in but I suspect it will only mellow slightly. Basically I want to see what's involved in warming it up a bit and to see what others have done.

My first area to look at would be the opamp doing the BAL/SE conversion. Who has rolled the opamp? What did you use or settle on, and did you achieve better results without sacrificing detail or resolution. The second area would be to change cap values, and if so which ones? Also if I switched the resistors to an "audiophile" brand is 1% ok?

Page 4 of the manual shows the ones that would or could be changed, but I'd need direction on which ones to change and what values to use.

Last edited by sbelyo; 1st August 2014 at 06:01 PM.
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Old 1st August 2014, 11:12 PM   #2
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I don't think modding the IVY will change the balance you are seeing. I have used the IVY and the Legato, I think that the Ivy had a tighter bass than the Legato. Switching power supplies on the Legato to the latest Placids made the Legato bass faster and more dynamic, which I thought bought it closer to the Ivy.

What power supply are you using for the Ivy?
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Old 2nd August 2014, 12:17 AM   #3
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Default Lots...

of options here... First of all, 1% is not good enough for the IVY-III resistors. You want to match all resistor pairs to at least .1%.

The output filtering in the stock IVY-III is already pretty strong, so I would not change that. But you could try different passive parts. Things like Takman Carbon Film resistors are a little warmer than most metal film types, but you will need to purchase a bunch of 1% resistors to get enough to match to .1%
For the filter circuit caps in the IVY-III you might try the Amtrans (Parts Connexion has them) capacitors in place of the stock Wimas as well.
Also, if you are using TPA Shunt regs to power it, try upping the CCS current. TPA mentions shunting 60 mA or so, try shunting 100 mA and see if you hear a difference (watch the heat when upping the CCS current).
Also, please describe the whole chain: what is the input to the B-IIIse? Are you running the fast or slow roll off FIR filter?
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Old 2nd August 2014, 02:10 PM   #4
4est is offline 4est  United States
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Prudent advice- the CCS does make a difference... Wima caps suck too btw, as do most metalized caps. They always have, even when there were fewer options.
Quote:
Originally Posted by barrows View Post
For the filter circuit caps in the IVY-III you might try the Amtrans (Parts Connexion has them) capacitors in place of the stock Wimas as well.
Also, if you are using TPA Shunt regs to power it, try upping the CCS current. TPA mentions shunting 60 mA or so, try shunting 100 mA and see if you hear a difference (watch the heat when upping the CCS current).
Also, please describe the whole chain: what is the input to the B-IIIse? Are you running the fast or slow roll off FIR filter?
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Old 2nd August 2014, 04:34 PM   #5
sbelyo is offline sbelyo  United States
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Quote:
Originally Posted by MartinC700 View Post
I don't think modding the IVY will change the balance you are seeing. I have used the IVY and the Legato, I think that the Ivy had a tighter bass than the Legato. Switching power supplies on the Legato to the latest Placids made the Legato bass faster and more dynamic, which I thought bought it closer to the Ivy.

What power supply are you using for the Ivy?
Placid HD Bi Polar
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Old 2nd August 2014, 04:38 PM   #6
sbelyo is offline sbelyo  United States
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Quote:
Originally Posted by barrows View Post
of options here... First of all, 1% is not good enough for the IVY-III resistors. You want to match all resistor pairs to at least .1%.

The output filtering in the stock IVY-III is already pretty strong, so I would not change that. But you could try different passive parts. Things like Takman Carbon Film resistors are a little warmer than most metal film types, but you will need to purchase a bunch of 1% resistors to get enough to match to .1%
For the filter circuit caps in the IVY-III you might try the Amtrans (Parts Connexion has them) capacitors in place of the stock Wimas as well.
Also, if you are using TPA Shunt regs to power it, try upping the CCS current. TPA mentions shunting 60 mA or so, try shunting 100 mA and see if you hear a difference (watch the heat when upping the CCS current).
Also, please describe the whole chain: what is the input to the B-IIIse? Are you running the fast or slow roll off FIR filter?
I'll shunt 100mA to see what the difference is. I am using the fast roll off
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Old 2nd August 2014, 04:40 PM   #7
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Default Not metalized...

Quote:
Originally Posted by 4est View Post
Prudent advice- the CCS does make a difference... Wima caps suck too btw, as do most metalized caps. They always have, even when there were fewer options.
The filter caps provided in the TPA kits are Wima FKP2, these are actually film/foil polyproplene capacitors and not metalized types. But I do feel there are better sounding options which will fit, like Amtrans... REL RTE polystyrene film/foil can be made to fit as well, but the Amtrans are a tad "warmer", perhaps.
Try the slow roll off filter as well...
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Old 2nd August 2014, 06:06 PM   #8
sbelyo is offline sbelyo  United States
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Source is a Music Hall CDP. Amplifiers are a single ended Dynahi and a Bottlehead Crack. Headphones are HD650, Headphile Darth Beyer V2, Joe Grado SR200
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Old 2nd August 2014, 07:30 PM   #9
sbelyo is offline sbelyo  United States
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Would a pair of opa627au on a browndog adapter work in place of IC5 (LM4562) ?
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Old 2nd August 2014, 09:22 PM   #10
sbelyo is offline sbelyo  United States
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I found this post from barrows on another forum

PRP resistors matched to 0.1% for feedback and filters
Takman Carbon Film resistors matched to ~0.1% for output resistors
Vishay Roderstein .1uF film caps for the supply decoupling to the opamps (better than Wima)
Amtrans 8.2 nF film/foil polypro caps for the analog filters (vs the stock 15nF Wimas)

My question is with the amtrans caps. What effect does reducing the value to 8.2 nf have?
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