Quickie 1.1 - Distortion

[Dogmeat]

I have had my Quickie 1.1 for a litte over 18 months and have been a very happy camper right from the start as it adds a little more magic to my system as well as some gain. I recently did some upgrades, i added tantulum resistors, replaced the pot with a TKD and replaced the coupling caps with Obligatos. As the obligatos are known to take al least 200 hours to breaking  in I was not overly concerned with the sound when i started it up. That was 4 months or so ago. I recently sat down for  to do some critical listening and noticed that my sound stage has completely colapsed, i am also getting high levels of distortion. I replaced the bateries (I did check the voltages) the soundstange remained small and the distortion was very pronounced at higher volumes.

Yesterday i removed the Quickie from my system and ran my DAC directly into my amp, which has a volume control, and the magic was back with no audible distortion with the volume at its highest, albeit a little less than with the Quickie in the system. I have no idea where to look, i am certain I did not make a mistake while doing the upgrade, i checked the solding and resoldered a lot of joints, just in case. One question remain, could it be the tubes that are failing? or is there something else i am missing?

Any help appreciated as i love the little amp

Thanks in advance

 

[Paul Joppa]

You can check the voltages, and the D-cell orientation (see sticky), to determine if the operating conditions are correct.

Assuming they are correct, your description makes me wonder if the power amp's volume control was turned down a touch when you were doing the critical listening. That would call for more output from the Q to get the expected loudness, and the Q is limited in that capability.

 

[Dogmeat]

The volume control on the amp is actually by passed, when i got the quickie i had no need for two volume controls in the system and decided to only use the quickie. When i did the test i was running foobar2000 and controlling the volume from within the software, ie the amp's volume is constant with or without the quickie.

Could it be that i am driving the quickie to hard at these levels? The TKD pot is log tappered, i do normal listening at the 8 - 9 o'clock position, when in the mood i migh move it the 12 o'clock position and every once on a blue moon will turn it all the way up to the 3 o'clock position. Distortion only really start from the 12 to 3 positions, first the highs and the lows. Funny thing is i used to do this without any ill effects before the upgrade and rocked the place (wife not home)

As for the soundstage, as a quick check i use Roger Waters Amused to Death to check imaging and sounstage, the perfect sense part 1 and 2 track is  great for this. It is a totally inmersive experience and many a visitor has been caught out thinking they are listening to surround, when it is only 2 channel stereo. Now the image and soundstage has completely retracted and the presentation is flat.

I am really getting close to ripping out the upgrade and revert to stock and see if that cures this wonderful little preamp.

 

[Paul Joppa]

At first, the OP said "... ran my DAC directly into my amp, which has a volume control ...", so I assume at some point that volume control was unbypassed. Now I understand, there are THREE volume controls, counting this and the Quickie and the digital control. So I am quite confused about what was heard when under what conditions.

That leaves the following speculations:

1) The Quickie is not operating right - hence my suggestion to check the voltages.

2) The Quickie is for some reason being overdriven when the soundstage problem is heard.

3) The digital volume is set too low, with loss of resolution the cause of the soundstage problem.

4) The new parts are awful in spite of their stellar reputation.

5) Something else changed in the system or the room.

The first three have to do with the settings of those three level controls. We don't have nearly enough information here on the Forum to assess the situation.

(In my previous post, I assumed there was no digital level control, hence its output was probably around 2.0 volts FS. The comment about the loudness being slightly less at full volume (I assumed that was the amp's control) compared to with the Quickie caused me to guess that when running loud the amp would call for more than 2.0v drive - which is getting close to the maximum available. Now I see that was too many assumptions to make without more detailed information.)

 

[Dogmeat]

Thanks for the reply,

Yes it was probably confusing and i do apologize. The main amp volume control has been bypassed ever since I introduced the Quickie into the system. My foobar2000 volume control is always maxed out, i do not like software volume controls due to the rounding or truncating that occurs. Hence with the Quickie in the system the ONLY active volume control is that of the Quickie. For the test i removed the Quickie and used the foobar volume control (the amp volume control is still bypassed) as i had no other means of controlling the volume. As the quickie produce about 10 db of gain, the volume of the system without the Quicky is slighty less. I trust it is now clear.

Before the mods, the system sounded wonderful and i could turn up the volume to max without any ill effects.
After the mods, the distortion starts as described above
When I removed the Quickie for the test, the magic reappeared just less loud.

i took her our of the system today. I checked all joints before i get to the testing and while doing so, noticed that i have connected the obligatos differently (left channel inside lead to positive and outside lead to negative, right channel, inside lead to negative and outside lead to positive). I removed them and returned the stock coupling caps. Did all the tests which was ok and then she went back into the system and the magic was back.

The question now is, which lead is positve and which lead negative on the obligatos or are they non polarized? If non polarized, in theory, it should not matter how they are connected, why then did they behave so ugly in the system? I have tried obtaining info on the web but there is no spec sheet out there, just ads and shopping carts.

Thanks in advance.

 

[Dogmeat]

A quick update on the voltages. When i checked the voltages last night, i checked those as indicated in the JPCCS manual, the voltages were:
1A/1B = 37.71 VDC
A6/B6 = 23.24/28.1 VDC
A5/B5 = 2 VDC

I went back this morning and checked the voltages as indicated in the Quickie manual, the voltages were:

Terminal                A side      B side
1,6                          23.2        28.2
2,7                          mV          mV
4,9                            2              2
5,10                          0              0
Rotary D                            3.6
Rotary C                            3.6

The voltage at terminal 6 is substantially larger than on terminal 1, and the voltages on terminal 2 and 7 measured in the mV range and not the 38 volts indicated in the manual.

She is playing nicely and doing what i was used to before the upgrade, but why do i get this diferences in the voltages and what effect does it have on the sound?

I also checked the resitance values as indicated in the Quickie manual and have the following differences:
Rotary switch 1 and 4 = 86,4 kohm and not infinity
Potentiometer Center terminals = 4,4 ohm and not 0-100 kohm

I might have made a mistake when i did the original built and have just never picked it up, is what i am used to wrong?

thanks in advance