[soren_brix]

Oh wow. Am I glad I asked! Thanks!

Donald is very helpful and provides a rather detailed step-by-step assembly guide, along with step-by-step testing to make sure the assembled circuit actually works.The only thing you need to add is the PC-supply, a box, some sockets, and lots of beads (as Donald points out).

 

[JimL11]

Not a problem at all Jim. I apologize for being so naive about all of this. I never considered this as a hobby until very recently. The learning curve is astronomical, but I find it enjoyable nonetheless.

I have so many questions as a newbie and I greatly appreciate those who take the time to offer their insight.


For one, with the SRM-007tII I get crosstalk between the inputs. Meaning, if I turn the volume up very high and am listening to channel two, I will hear the sound on input 1. Is this normal with such an amp? Is this a grounding issue? While it should not be a big deal, I am surprised to hear it.

Also, can anyone compare/contrast this bass when upgrading from say the 007tII to a BHSE or something on that level? I feel like I’m hearing wonderful mids and highs with the 009s, and great separation. I hear all of the instruments with great detail, but I find the bass lacking. I’m aware that the 007s may offer more bass, but currently I own 009s and plan to stick with them for quite a while.

Lastly, is there a technical way to balance the left and right channels or do you just rely on your ears for what sounds good? There is a knob in addition to the volume knob on the right of this amp for controlling the balance. I turn it all the way to the left and the volume is loud on the left. I turn it all the way to the right and it is certainly not as loud in the right when compared to the left.

I find this frustrating, but I’m not sure much is to blame on the amp, my lack of technical know-how, or the headphones.

Helpful and positive comments area greatly appreciated.

If you look at the input wiring, you'll see that input 1 and 2 run parallel to each other from the back of the amp to the front, so it's not surprising that if you crank the volume up there will be some cross-talk. Just turn off the source to the input you're not using.

The bass issue has been noted by others - see the InnerFidelity review of the SRM007. This is in large part due to the fact that the output stage uses plate resistors, which suck up a significant amount of signal current by Ohm's law. Changing to constant current loads (such as in the T1 mod) can largely mitigate this issue. Obviously, changing to the significantly more powerful BHSE, which uses constant current output loads, or another upgrade (e.g. SRX-Plus, KGSSHV, KGST, KGSS Carbon, Megatron), will also improve the bass significantly.

The Stax amps use concentric volume controls which are clutched together to adjust balance between channels, as you have discovered. If the controls tracked perfectly, then once they are balanced at one setting they should remain in balance. In practice, they are close enough at higher volumes but may deviate at low volume. This means that if you rotate both all the way up, and rely on the clutch to keep them aligned, they should be in close balance for much of the volume range, but you if you are listening at low volumes you may need to make an adjustment. OTOH, usually if you are listening at low volumes you are using it as background in which case balance is much less critical.

 

[yakaway]

What a great answer Jim. Thank you for informing us. I was worried I was being too critical of this amp, but for me, I think I'll be looking to upgrade soon!

My opinions here are my own. I'm new to the hobby. I don't read the reviews and follow the flock, yet. These are my observations and I'm doing this intentionally as of right now.

What's the sense in spending 10k on gear if you can't appreciate its greatness or point out faults in a lesser quality setup.

When I first tried the 009s, I knew they are something special, just not dialed in as say perhaps, my focal utopias with chord hugo 2. That hit me immediately as completely wonderful.

Bhse... kgsshv... bhse... kgss carbon... I guess I'll have to flip a coin tonight

 

[weasel1979]

bhse or carbon, thats my question.. (for SR-007)

 

[Muffinhead]

What a great answer Jim. Thank you for informing us. I was worried I was being too critical of this amp, but for me, I think I'll be looking to upgrade soon!

My opinions here are my own. I'm new to the hobby. I don't read the reviews and follow the flock, yet. These are my observations and I'm doing this intentionally as of right now.

What's the sense in spending 10k on gear if you can't appreciate its greatness or point out faults in a lesser quality setup.

When I first tried the 009s, I knew they are something special, just not dialed in as say perhaps, my focal utopias with chord hugo 2. That hit me immediately as completely wonderful.

Bhse... kgsshv... bhse... kgss carbon... I guess I'll have to flip a coin tonight

Just get the most expensive one. It sounds like you want to and can afford it. Or you could get a cheaper amp and buy the SR007's with the extra money.

 

[statfi]

Is there any wisdom of when to turn off your BHSE or equiv. between listening sessions to maximize tube life? If I am doing one listening session per day, I *think* its a no brainer: always turn it off at the end of the listening session. But let's say I am doing 3 30 min listening sessions per day, spaced by H hours. How long does H have to be to justify turning the BHSE off after each of the 3 sessions that day, to maximize tube life?

 

[Whitigir]

Is there any wisdom of when to turn off your BHSE or equiv. between listening sessions to maximize tube life? If I am doing one listening session per day, I *think* its a no brainer: always turn it off at the end of the listening session. But let's say I am doing 3 30 min listening sessions per day, spaced by H hours. How long does H have to be to justify turning the BHSE off after each of the 3 sessions that day, to maximize tube life?

You are over thinking. Just enjoy them

 

[JimL11]

Just get the most expensive one. It sounds like you want to and can afford it. Or you could get a cheaper amp and buy the SR007's with the extra money.

Now, if you're willing to DIY, the monetary cost will be significantly less. You will have to put in time and effort, but there is the pride of saying you built it yourself. In that case, the least expensive and simplest to build is the SRX-Plus - I built mine point-to-point, but Kevin Gilmore has the files to send to a board maker to produce your own printed circuit board. Using surplus transformers and heatsinks off eBay, it cost way less than $1k in parts including the enclosure. This has sufficient power for any Stax headphone including the SR-007, is in the same class as the KGST/KGSSHV, albeit with a somewhat different sound signature.

 

[JimL11]

You are over thinking. Just enjoy them

1+. The BHSE runs its EL34s at about 10 watts plate dissipation, which is about 40% of maximum, so they are basically loafing, and should last 10-20,000 hours.

 

[1note]

Would someone please please help!? I want to make the internal TVR1, TVR2, TVR3 and TVR4 pot settings adjustments after changing the 4 tubes in my SRM-007tII without blowing anything up. I am not an engineer but I am capable of following step-by-step instructions. I have 1 question. Is KG’s outline all I need to do? It seems simpler than the JimL11 + ColoradoTom outline. Many thanks in advance!

KG Outline

- Start with control pots set to the middle

Repeat the following a few times over 30 minutes
- Put voltmeter probes between TP1 and TP2 and adjust TVR1 for zero
(if you have to turn tvr1 more than .25 turn in either direction, stop and get new tubes)
-Then put a voltmeter between either TP1 or TP2 and Ground and adjust TVR2 for zero
-Then put a voltmeter between both TP1 and adjust TVR3 to zero
-Then put a voltmeter between both TP2 and adjust TVR4 to zero
end repeat

JimL11 + ColoradoTom outline

1. TVR1 adjusts voltages between + and - outputs for each channel

a. Insert positive probe into slot labeled “L+” and insert negative probe into slot labeled “L-”.

b. Adjust potentiometer labeled “TVR1” for the left channel. The potentiometer is EXTREMELY sensitive and the meter reading will have a tendency to drift around a bit. The goal is to get under 1 volt.

2. TVR2 adjusts the voltages of the outputs to be close to zero volts with respect to ground

a. Leave positive probe in slot labeled “L+”

b. Remove negative probe from slot labeled “L-” and attach to ground at back of amp. The goal is to get under 1 volt.

3. By alternating negative probe between ground at back of amp to slot labeled “L-” recheck and adjust TVR1 and TVR2 respectively

4. TVR3 and TVR4 - they adjust the plate voltages for the two sections of each 6CG7/6FQ7 to be equal to each other. Connect a voltmeter between both TP1 points or both TP2 points and adjust TVR3 and TVR4 so that the voltage between the two is zero.

 

[oktapod]

Has anyone heard any of Mjolnir's new, more affordable KGSSHV Minis? I am seriously tempted. Apparently slightly lower voltage - 360V rather than 400V - would this result in a slightly less dynamic sound, or simply limit absolute headroom for the highest listening levels? My 007 mk1s should have arrived yesterday but my town is cut off in all directions by snow so it's going to be tomorrow or Saturday at the earliest. Then I will compare against L700 (with 006T) which I expect to be the more balanced system, but hoping to glimpse some of what a 007mk1 can do by listening at lower volumes which shouldn't tax the 006T so much.

 

[Muffinhead]

Now, if you're willing to DIY, the monetary cost will be significantly less. You will have to put in time and effort, but there is the pride of saying you built it yourself. In that case, the least expensive and simplest to build is the SRX-Plus - I built mine point-to-point, but Kevin Gilmore has the files to send to a board maker to produce your own printed circuit board. Using surplus transformers and heatsinks off eBay, it cost way less than $1k in parts including the enclosure. This has sufficient power for any Stax headphone including the SR-007, is in the same class as the KGST/KGSSHV, albeit with a somewhat different sound signature.

Now you have caught my interest. How much, more or less, would the components for such an amp cost? Is there a BOM and schematic available for such a device? I don't have anywhere near the time to do this, nor do I have the knowledge, but I would fo it down the road.

 

[soren_brix]

I got a set of SR-X boards 2mm/4oz that I don't mind departing from

 

[1note]

 

[joseph69]

How's the Terminator with you're system?