Recent Posts

11

Stereomour II / Re: "Lost" resistors found Aha! moment EDITED

« Last post by Paul Birkeland on Yesterday at 01:48:32 PM »

The two 3650F 365 ohm (wattage not listed anywhere) resistors pictured/mentioned  on page 9, 47 and 48 of the procedure that I have, are NOT what was in my kit ordered Nov. 2022. I received two banded 1/8 watt resistors that are now left over as I am finally finishing things up.

Bottom line: A personal heads up memo in my personal kit from a personal small tube amp outfit about part substitutions, or any changes known at the time of building the kit that is hand picked for me that deviated from the provided procedure and parts list would have saved me much extra trouble and confusion. Either way, finally getting close to the end.

BTW, an accurate detailed  schematic with up to date nomenclature and values for EVERY component should be included in the price.

If we put a personal note in every kit every time we provided a resistor that's slightly different than what's in the manual, we might have to hire extra staff to accomplish this.  We are definitely not going to redraw the schematic as part of this process.  It is of great interest that the 365 ohm resistors on the schematic in the manual do not have a wattage value called out on them, as they dissipate 9/1000 of a watt and pretty much any old 365 Ohm resistor that exists is going to be overkill in that spot.  Also, you can use your meter to measure the resistance of any mystery resistors, then double check what you measure against the parts list.

We do have a note on the parts list that clarifies this point.

12

S.E.X. Kit / Re: S.e.x. with iron upgrade

« Last post by Paul Joppa on Yesterday at 01:32:56 PM »

Thanks for the pictures. That is a SEX 2.0 with the Bottlehead Iron Upgrade kit (and a lot of other cool mods!)

On pages 10 and 11 of the upgrade kit manual, there are detailed instructions and photos for wiring the OT-2 output transformer for 4/8/16/32 ohms.

In case you no longer have the manual, I've attached a set of connection instructions, unfortunately without photos. The numbers refer to the solder lug numbers embossed on the transformer bobbin. (Lugs 4 and 9 are the missing ones.)

13

Eros Phono / Re: Eros VDC

« Last post by bucketofguts on Yesterday at 12:05:21 PM »

I ordered a new C4S board and all new parts + an extra MJE350 and a 2N222 to put in my original board to try.. Hearing that the circuit can damage a 6922 hurts. I been putting Amperex American white lable PQ's in rotation each time I reflowed/ reheated. Have Mercy!

14

S.E.X. Kit / Re: S.e.x. with iron upgrade

« Last post by tttubes on Yesterday at 11:20:58 AM »

and this

15

S.E.X. Kit / Re: S.e.x. with iron upgrade

« Last post by tttubes on Yesterday at 11:19:10 AM »

That depends on which S.E.X. amp version you have. Here are the versions:

Original SEX monoblocs (Magnequest upgrade TFA-204)
Revision 1.0 (1996) (Magnequest upgrade TFA-204)
Revision 1.1 (1996) (Magnequest upgrade TFA-204)
Revision 2.0 (1997) (Magnequest upgrade TFA-204)
ParaSEX (1999) (no upgrade)

Stereo SEX

ersion 2.0 (2004) (Magnequest upgrade BH-2 choke, BH-1 transfprmer 8 ohms only)
     (Bottlehead upgrade PC-3 choke, OT-2 transformer)
Revision 2.1 (2011) (stock Bottlehead PC-3 choke, OT-2 transformer - no upgrades)
Revision 3 (2017)  (stock Bottlehead PC-3 choke, OT-2 transformer - no upgrades)

Do these pics help I it saw a one

16

S.E.X. Kit / Re: S.e.x. with iron upgrade

« Last post by Paul Joppa on Yesterday at 10:17:23 AM »

That depends on which S.E.X. amp version you have. Here are the versions:

Original SEX monoblocs (Magnequest upgrade TFA-204)
Revision 1.0 (1996) (Magnequest upgrade TFA-204)
Revision 1.1 (1996) (Magnequest upgrade TFA-204)
Revision 2.0 (1997) (Magnequest upgrade TFA-204)
ParaSEX (1999) (no upgrade)

Stereo SEX
Version 2.0 (2004) (Magnequest upgrade BH-2 choke, BH-1 transfprmer 8 ohms only)
     (Bottlehead upgrade PC-3 choke, OT-2 transformer)
Revision 2.1 (2011) (stock Bottlehead PC-3 choke, OT-2 transformer - no upgrades)
Revision 3 (2017)  (stock Bottlehead PC-3 choke, OT-2 transformer - no upgrades)

17

Stereomour II / "Lost" resistors found Aha! moment EDITED

« Last post by patrick620 on Yesterday at 09:53:23 AM »

The two 3650F 365 ohm (wattage not listed anywhere) resistors pictured/mentioned  on page 9, 47 and 48 of the procedure that I have, are NOT what was in my kit ordered Nov. 2022. I received two banded 1/8 watt resistors that are now left over as I am finally finishing things up. I had replacements on hand way back then so no biggie. I only post this in case someone else does not think they were shorted in the kit or lost them at home. This whole thing did cause me some confusion and some hands on my knees time looking for lost parts, getting back up from the floor is the hard part.

Bottom line: A personal heads up memo in my personal kit from a personal small tube amp outfit about part substitutions, or any changes known at the time of building the kit that is hand picked for me that deviated from the provided procedure and parts list would have saved me much extra trouble and confusion. Either way, finally getting close to the end.

BTW, an accurate detailed  schematic with up to date nomenclature and values for EVERY component should be included in the price.

18

S.E.X. Kit / S.e.x. with iron upgrade

« Last post by tttubes on Yesterday at 08:48:46 AM »

How would i wire  the magequest otf for 4 ohms.

19

S.E.X. Kit / Re: Am I pushing the amp too hard?

« Last post by Paul Birkeland on January 26, 2025, 03:02:58 PM »

I have to turn the volume knob up to about 3 o'clock to get a good amount of volume.
1. Does this seem 'ball park' correct for sensitive speakers?

There isn't anything to read into here.  The level of signal coming into the SEX amp will depend a lot on the specific source component you're using.  The amp will play a lot quieter at that volume setting when fed by the headphone output of a phone compared to the output of a Lumin streamer.  I'd expect that specific difference on its own to be over 20dB.

2. If I am cranking the volume knob up, am I also pushing the tubes (or just the amp in general) too hard?

The amp is class A.  It's always running about as hard as it can.

I ask because I recently plugged a set of headphones (Grado SR325x) to be sure that the headphone input was functioning properly and I only had to turn the volume up to 9 o'clock to achieve a significant amount of volume.

Grados need very, very little power to go to full volume, so this isn't surprising.

It all seems fine. I am not hearing any distortion.

That's all that really matters in the end!

20

S.E.X. Kit / Am I pushing the amp too hard?

« Last post by pbvoorhees on January 26, 2025, 02:43:38 PM »

Greetings everyone,
I completed building the S.E.X. 3.0 a few weeks back. It's my first build.
I am really enjoying the amp. I built it to use primarily with sensitive speakers.
Pardon if this is a very basic question, but when listening to the S.E.X. with speakers (98db sensitivity @ 8ohms), I have to turn the volume knob up to about 3 o'clock to get a good amount of volume.
1. Does this seem 'ball park' correct for sensitive speakers? And,
2. If I am cranking the volume knob up, am I also pushing the tubes (or just the amp in general) too hard?
I ask because I recently plugged a set of headphones (Grado SR325x) to be sure that the headphone input was functioning properly and I only had to turn the volume up to 9 o'clock to achieve a significant amount of volume.
I know we all have different ideas about what a 'good amount of volume' is and I am also not forgetting that this is a two watt amp.
I guess I am really asking if cranking the volume knob up very high while using the S.E.X to listen with speakers is at all damaging to the amp.
It all seems fine. I am not hearing any distortion. I just want to be sure I am taking good care of this new piece of equipment.
Thanks for considering this question.
Pieter